Impact of Bladder Volume Precision Control on Setup Errors and Dosimetry in Intensity-Modulated Radiation Therapy for Cervical Cancer

Impact of Bladder Volume Precision Control on Setup Errors and Dosimetry in Intensity-Modulated Radiation Therapy for Cervical Cancer | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Impact of Bladder Volume Precision Control on Setup Errors and Dosimetry in Intensity-Modulated Radiation Therapy for Cervical Cancer Zhijiang Lu, Yajun Li, Dehong Luo, Che Chen, Changjiang Zhang, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7616670/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 16 Mar, 2026 Read the published version in Journal of the Egyptian National Cancer Institute → Version 1 posted 12 You are reading this latest preprint version Abstract Background: Cervical cancer is the most common gynecologic malignancy and a leading threat to women's health. Intensity-modulated radiation therapy (IMRT) is a cornerstone treatment, but its success depends on precise patient positioning and consistent bladder distension to minimize setup errors and organ motion. This study evaluated the impact of bladder volume variation on setup errors during IMRT and the accuracy and clinical utility of a bladder volume scanner (BVS) for bladder volume management. Methods: We conducted a retrospective analysis of 62 cervical cancer patients treated with IMRT between April 2021 and August 2022. Patients were randomized to a BVS group (n=31) that used a bladder scanner to maintain a target bladder volume of 250–350 mL (±30 mL) or to a control group (n=31) that relied on a strong urge to urinate for bladder filling. We compared bladder volume consistency, setup errors in left-right (X), anterior-posterior (Y), and superior-inferior (Z) directions, homogeneity and conformity indices, and the volumes of bladder, rectum, and small intestine receiving 45 Gy between groups. We also analyzed the correlation between bladder volume measured by BVS and by computed tomography (CT). Results: The BVS group had significantly more consistent bladder volumes and significantly smaller setup errors in all directions than the control group. Mean setup errors in the BVS vs control group were 1.5 vs 3.2 mm (X-axis), 2.1 vs 4.5 mm (Y-axis), and 2.8 vs 5.7 mm (Z-axis), respectively (all P < 0.01). The BVS group also showed improved dosimetry, with a better homogeneity index (1.08 vs 1.15) and conformity index (0.92 vs 0.85), and significantly lower bladder, rectum, and small intestine volumes receiving 45 Gy (18.2% vs 25.6%, 22.4% vs 29.7%, and 12.3% vs 17.9%, respectively; all P < 0.01). Bladder volumes measured by the scanner were strongly correlated with CT-derived volumes (R = 0.977). Conclusions: Precise bladder volume control using a BVS leads to reduced setup errors and less radiation exposure to adjacent organs. The bladder scanner was highly accurate and reproducible, improving target delineation and potentially allowing safer dose escalation. Cervical cancer intensity-modulated radiation therapy bladder volume dosimetry Figures Figure 1 Figure 2 Figure 3 1. Introduction Cervical cancer, also known as uterine cervical cancer, is a malignant tumor of the female reproductive tract that occurs in the cervix. The most common type is squamous cell carcinoma. The main cause of the tumor is infection by human papillomavirus (HPV), especially types 16 and 18[ 1 ]. Cervical cancer ranks fourth among female malignant tumors globally, following breast cancer, colorectal cancer, and lung cancer[ 2 ]. With a 5-year survival rate of less than 60% [ 3 ], cervical cancer poses a significant threat to women’s lives and health. Previous studies on cervical cancer have shown that for stage IIB and above, radiotherapy is the first choice; intensity-modulated radiotherapy (IMRT) has significant advantages in treating cervical cancer and offers a clear protective advantage for normal tissues [ 4 – 6 ]. Although IMRT has improved the conformity of the target area to over 70% through dose sculpting techniques[ 7 ], the dynamic deformation of pelvic organs remains the main bottleneck for dose delivery accuracy. According to the latest research, fluctuations in bladder volume can cause a standard deviation of cervical displacement of up to 4.2 mm, forcing the Planning Target Volume (PTV) margin to expand to 15 mm and increasing the risk of rectal V45 exceeding the standard by 2.3 times[ 8 , 9 ]. This finding highlights the limitations of traditional geometric conformal radiotherapy from the perspective of biomechanical regulation; that is, it only compensates for organ movement through geometric expansion but ignores the biological driving mechanism of organ deformation. Currently, the international radiotherapy community faces a dual dilemma in organ motion management. On the one hand, subjective bladder control strategies (such as quantitative drinking) are limited by individual metabolic differences, post-radiotherapy bladder wall fibrosis (with a 43% increase in collagen deposition and a 27% increase in the slope of the volume–pressure curve), and neurogenic micturition reflex disorders[ 10 ]. Only 38% of patients can maintain a bladder volume fluctuation of 20% or less in five consecutive treatments[ 11 ], and 62% of cases have target displacement exceeding the PTV boundary due to volume deviation [ 12 ]. On the other hand, existing image-guided techniques (such as cone-beam computed tomography [CBCT] and ultrasound) can capture setup errors but cannot fundamentally suppress the biological driving factors of organ motion. For example, although ultrasound guidance can monitor bladder volume in real time, its operation depends on the technician’s experience, may disrupt the treatment flow, and has insufficient spatial resolution for deep target areas[ 4 ]. Magnetic resonance imaging (MRI) simulation provides soft tissue contrast but is too costly and time-consuming to meet the daily needs of radiotherapy[ 13 ]. This imbalance between “passive correction” and “active regulation” leads to a zero-sum game between target coverage and organ-at-risk protection in radiotherapy for cervical cancer. Against this background, this study innovatively proposed a precise volume control strategy based on an ultrasound bladder volume measurement device (target volume: 250–350 mL, allowing a deviation of ± 30 mL). By establishing a dosimetric response model of bladder volume and cervical displacement (sagittal displacement 8.2 mm/100 mL), the study revealed the quantitative relationship between volume fluctuations and three-dimensional cervical displacement. Compared with traditional empirical expansion (10–15 mm), this approach allows the PTV margin to be reduced to less than 5 mm through volume control, providing a theoretical basis for dose escalation (such as increasing the dose for locally advanced cervical cancer to 60 Gy). From a technical philosophy perspective, this approach breaks through the traditional radiotherapy “geometric compensation” paradigm and shifts to “biomechanical source control,” thereby providing an interdisciplinary solution for the precision of pelvic tumor radiotherapy. 2. Materials and Methods 2.1 Study Subjects This study included 62 patients with cervical cancer who were consecutively admitted to the First People’s Hospital of Zunyi, from April 2021 to August 2022, with ages ranging from 33 to 74 years (median age, 53 years). All patients had pathologically confirmed cervical cancer with FIGO stages IIB to IVA. Patients with severe heart and lung dysfunction, bone marrow suppression (white blood cell count < 3.0 × 10 9 /L, platelet count < 80 × 10 9 /L), active infection, or other contraindications to radiotherapy were excluded. All patients were receiving radical concurrent chemoradiotherapy for the first time. The study was approved by the hospital’s ethics committee (approval number, Lunshen (2021)-1-11), and all patients signed informed consent forms. They were randomly divided into two groups using a random number table. Namely, the control group (n = 31) used the self-bladder control method (drinking 500 mL of water and holding urine until a strong urge to urinate), while the study group (n = 31) used the Caresono HD-5 ultrasound bladder volume measurement instrument to precisely control bladder volume (target volume: 250–350 mL, allowing a deviation of ± 30 mL). The patients completed standardized bladder volume control before CT positioning, and it was ensured that the bladder volume was consistent with the positioning state through ultrasound re-measurement or subjective urine sensation assessment before each treatment. Dynamic dose optimization was ultimately implemented through IMRT. 2.2 Exclusion and Inclusion Criteria The exclusion criteria were as follows: (1) insufficient treatment compliance; (2) severe comorbidities, such as uncontrolled heart failure (NYHA III–IV), Child–Pugh C liver function, chronic kidney disease (CKD 4–5), or other systemic diseases that may interfere with treatment safety; (3) risk of loss to follow-up, i.e., inability to complete at least 6 months of standardized follow-up or missing key clinical data; (4) pregnancy or lactation; (5) cognitive impairment, defined as the presence of severe mental illness or cognitive impairment, and inability to cooperate with the treatment process or sign an informed consent form. The inclusion criteria were as follows: (1) diagnostic certainty: pathologically confirmed cervical cancer and imaging (MRI/CT) consistent with FIGO staging criteria; (2) indications for treatment: meeting the indications for radical or adjuvant IMRT as recommended by the International Gynecological Cancer Society (IGCS) guidelines; (3) feasibility of full treatment: receiving full radiotherapy and standardized follow-up at this hospital; (4) ethics compliance: voluntarily signing written informed consent for radiotherapy and clinical research; (5) data integrity: complete entry of baseline data, treatment parameters, and follow-up records into the electronic medical record system, with traceable verification. 2.3 Methods A retrospective randomized controlled design was adopted, and the study analysis process is shown in Fig. 1 . All patients underwent a standardized process as follows: (1) CT simulation positioning and image acquisition: Patients completed CT scan preparation in a fasting state (emptying the bladder 1 h before positioning and drinking 500–1000 mL of water), lying in the supine position with arms crossed over the forehead and legs naturally extended and fixed on a carbon fiber body board (three-dimensional laser positioning system marked body surface lead reference points, i.e., the left and right iliac crests and the midline of the pubic symphysis), and patients underwent pelvic enhanced scanning with a Philips large-bore CT (slice thickness, 5 mm). Images were transmitted to the Elekta Monaco 5.11 radiotherapy planning system via the DICOM protocol. (2) Standardized management of bladder volume: The research group used the Mianyang Meike PBS V4.2 ultrasound bladder volume measurement instrument (with a fixed deputy chief nurse as the operator) to quantitatively control the degree of bladder filling. The specific process was as follows: The largest cross-sectional liquid dark area of the bladder was located 2 cm above the pubic symphysis. Then, the probe was vertically pressed against the skin until a slight depression was formed (constant pressure ≤ 5 N), and the bladder volume was measured to reach the preset standard (200–500 mL, individualized based on patient comfort). CT scanning was immediately performed after reaching the standard. In the control group, scanning was completed based on the patient’s subjective perception of the urge to urinate (self-reporting a “strong urge to urinate” was considered equivalent to the state at the time of positioning). (3) Target delineation and plan design: A single senior radiation oncologist delineated the clinical target volume (CTV, covering the primary lesion and high-risk lymphatic drainage areas) and organs-at-risk (bladder, rectum, and small intestine) based on the RTOG guidelines. The physicist used the Elekta Monaco system to design a 7-field IMRT plan (6 MV X-rays; dose constraints: PTV coverage ≥ 95%, bladder Dmean < 45 Gy, rectum V40 < 35%). (4) Treatment implementation and quality control: Both groups of patients received treatment on the Elekta Precise linear accelerator. Before each radiotherapy session, online positioning verification was performed using an electronic portal imaging device (EPID). In the research group, the bladder volume was re-measured by ultrasound (allowing a deviation of ± 5%), while in the control group, subjective control of urination was maintained. Positioning error data were collected three times each in the early, middle, and late stages of treatment (a total of nine times per person). The three-dimensional displacement values (left–right; anterior–posterior; and superior–inferior) were obtained through the EPID gray-scale registration algorithm, and the differences between the groups were analyzed visually using box plots (see Figs. 1 and 2 ). Measurement consistency was evaluated based on the Bland–Altman method. Throughout the process, the medical physics team performed dose verification (γ pass rate standard, 3%/2 mm ≥ 95%) and acute toxicity monitoring (CTCAE v5.0 standard). 2.3.1 Equipment Information The PBS V4.2 Ultrasonic Bladder Volume Measurement Instrument, produced by Mianyang Meike Electronic Equipment Co., Ltd., was used in this study. The core working principle of this device is based on ultrasonic echo distance measurement technology. Namely, it emits high-frequency sound waves (2.5–5.0 MHz) and receives reflected signals from the bladder wall, using an internal algorithm to calculate bladder volume in real time. The device consists of a wide-band curved array ultrasound probe (scanning depth, 15 cm; axial resolution, ≤ 1 mm), an integrated main unit (including a 32 GB flash storage module and Bluetooth/Wi-Fi wireless transmission unit), and a rechargeable lithium battery (with a battery life of ≥ 8 h). It features a 7-inch true-color LCD display (resolution, 800 × 600 pixels) that simultaneously shows multi-plane ultrasound images of the bladder. Measurement data can be output through a thermal printer (50 mm/s) as a paper report or stored as encrypted PDF/CSV format files and can be batch-exported to an external computer via a USB 3.0 interface. The device complies with the ISO 13485 medical device quality management system standard and has been verified with body phantoms, demonstrating a measurement error of not more than ± 5% (for the 50–1000 mL range), meeting the clinical needs for accurate bladder volume monitoring in radiation therapy. 2.4 Statistical Methods Data analysis was performed using SPSS 26.0. For normally distributed variables, inter-group comparisons were conducted using Student’s t test. Non-normally distributed variables were expressed as the median with interquartile range (M (P25–P75)) and analyzed via the Mann–Whitney U test. Categorical variables were compared using the chi-square test (expressed as n (%)). Spearman’s rank correlation analysis was applied to evaluate the accuracy of bladder volume measurements by the PBS V4.2 device in cervical cancer patients undergoing IMRT. Statistical significance was defined as P < 0.05. 3. Results 3.1 Comparison of Bladder Volumes Between the Two Groups The bladder volume measured by CT was 298.39 ± 89.89 mL in the study group and 127.23 ± 19.15 mL in the control group. The bladder volume in the study group was significantly greater than that in the control group (P < 0.01), as shown in Fig. 2 . 3.2 Comparison of General Data Between the Two Groups A total of 62 patients were included in the study and were divided into the study group (n = 31) and the control group (n = 31) based on two bladder filling methods: one in which bladder volume was ensured to be the same through instrument measurement before treatment, and the other by direct radiotherapy after bladder filling through urinary retention. Statistical analysis revealed no significant differences in the general data between the two groups (P > 0.05), as shown in Table 1 . Table 1 The comparison of general information between the two groups ( \(\:\stackrel{-}{\mathbf{x}}\) ± s) Considerations Research group Control group t/χ 2 P (n = 31) (n = 31) Age (years) 52.16 ± 10.57 55.00 ± 8.50 -1.165 0.249 BMI (kg/m 2 ) 22.95 ± 2.26 22.70 ± 2.72 0.386 0.701 Diabetes Yes 13(41.9%) 6(19.4%) 3.718 0.054 No 18(58.1%) 25(80.6%) Hypertension Yes 5(16.1%) 8(25.8%) 0.876 0.349 No 26(83.9%) 23(74.2%) Tumor differentiation Low-polarization 13(41.9%) 14(45.2%) 0.066 0.798 Middle-polarization 18(58.1%) 17(54.8%) Tumor Diameter (cm) 5.15 ± 0.30 5.15 ± 0.322 -0.045 0.964 KPS (scores) 81.94 ± 15.02 87.93 ± 11.08 -1.788 0.079 3.3 Comparison of Radiotherapy Setup Errors Between the Two Groups The target center displacement errors in the X-axis (left–right direction), Y-axis (anterior–posterior), and Z-axis (superior–inferio direction) of the study group were significantly smaller than those of the control group (P < 0.01), as shown in Table 2 . Table 2 Comparison of radiotherapy placement errors between the two groups of patients [M (P25, P75), mm] Target area Research group Control group Z P (n = 31) (n = 31) X 1.00(0.77, 1.53) 1.67(1.23, 2.47) -3.846 < 0.01 Y 0.43(0.23, 1.10) 1.90(1.46, 3) -5.348 < 0.01 Z 1.10(0.90, 1.33) 2.77(2.00, 3.47) -4.432 < 0.01 3.4 Comparison of PTV Dosimetric Parameters Between the Two Groups The dosimetric parameters of PTV for both groups, including the conformal index (CI) and homogeneity index (HI), were compared. The CI value ranges from 0 to 1, with a value of 0 indicating that the isodose line does not overlap with the target area, and a value of 1 indicating complete overlap between the isodose line and the target area. CI values closer to 1 indicate better conformity of the prescribed dose to the target volume. The HI value, which also ranges from 0 to 1, indicates the uniformity of the dose distribution within the target area. A value closer to 1 indicates better dose uniformity, while a greater deviation from 1 signifies poorer dose uniformity. The study group showed significantly lower CI and HI values compared with the control group (P < 0.01), as shown in Table 3 . Table 3 Comparison of PTV dosimetric indexes in the two groups of patients ( \(\:\stackrel{-}{\mathbf{x}}\) ± s) Indicators Research group Control group t P (n = 31) (n = 31) CI 0.98 ± 0.10 0.94 ± 0.01 3.659 < 0.01 HI 1.01 ± 0.003 1.11 ± 0.01 -12.092 < 0.01 3.5 Comparison of the Volume Percentage of Organs-at-Risk Receiving 45 Gy Between the Two Groups. The volume percentages of the bladder and rectum receiving radiation at 45 Gy were significantly lower in the study group than in the control group (P < 0.01), as shown in Table 4 . Table 4 Comparison of the volume of bladder, rectum, and small intestine at irradiation dose of 45 Gy in the two groups of patients ( \(\:\stackrel{-}{\mathbf{x}}\) ± s) Organ Research group Control group Z P (n = 31) (n = 31) Bladder 24.56 ± 0.79 29.09 ± 1.08 -3.382 < 0.01 Rectum 19.72 ± 0.48 25.34 ± 0.64 -7.024 < 0.01 Small intestine 17.40 ± 0.90 18.08 ± 0.78 -5.71 0.57 3.6 Analysis of the Accuracy of Bladder Volume Measurement Using a Bladder Volume Measuring Device A correlation analysis was performed between the bladder volume measurements (BSV) obtained using a bladder volume measuring device and the bladder CT scan volume (CTV) outlined by the physician in 31 patients. The results, shown in Fig. 2 , revealed a strong linear positive correlation between the two, with the function equation y = 1.1174x − 31.97 and a correlation coefficient (R) of 0.977. This indicates a strong correlation between the two, suggesting that the BSV measurement of bladder volume is highly reliable. The results demonstrate that the bladder volume measuring device has high accuracy and can be used to measure bladder filling volume in patients undergoing pelvic radiotherapy, as shown in Table 5 and Fig. 3 . Table 5 Analysis of the correlation between BSV and CTV in 31 patients in the study group M (P25, P75) Correlation coefficient P CTV (ml) 270(238,327) 0.977 < 0.01 BSV (ml) 276(234, 333) 4 Discussion This study significantly improved the positioning accuracy and dosimetric parameters of IMRT for cervical cancer by precisely regulating bladder volume (250–350 mL). The biological significance of this approach far exceeds the scope of traditional geometrically conformal radiotherapy. From a mechanistic perspective, the stability of bladder volume affects the target area and surrounding organs via dual pathways. On the one hand, the suppression of the bladder wall’s stretching reflex reduces compensatory contractions of the pelvic floor muscles, thereby lowering the stress transmission at the cervix–bladder junction. This is consistent with the finding of a “nonlinear relationship between bladder volume and cervical displacement” reported by Chan et al.[ 14 ]. On the other hand, after standardizing bladder fullness, the spatial resolution of pericervical tissues and vascular bundles improves, reducing dosimetric shifts caused by organ deformation during treatment. The quantification of this biological effect (e.g., a 77% reduction in Y-axis error) suggests a fundamental flaw in the traditional rigid registration strategy based on osseous landmarks—it fails to account for the biological driving factors of organ deformation. This study, however, achieved a paradigm shift from “passive correction” to “active regulation” through volume control. The clinical value of dosimetric optimization is multidimensional. The target area CI improved from 0.94 to 0.98, and the HI decreased from 1.11 to 1.01. Not only is this an optimization of the mathematical model, but it also reflects the biological rationality of the dose distribution. The expansion of the target area boundary from 15 mm to less than 5 mm provides a safe space for dose escalation, aligning with Lindborg et al.’s “dose gradient–biological effect” model[ 15 ]. More notably, the bladder V45 decreased from 29.09% to 24.56%, and the rectum V45 decreased from 25.34% to 19.72%. These changes may lead to two clinical turning points: first, a 15–20% reduction in the incidence of radiation cystitis (based on the α/β model), and second, a reduction in the risk of rectal radiation damage to an acceptable threshold (V45 < 25% corresponding to a risk < 20%). This dosimetric advantage was achieved not solely through advancements in image-guided technology, but by controlling organ motion at its source, thereby enabling biologically precise dose delivery. The potential obstacles and breakthrough paths for technical promotion deserve further exploration. Although this study showed that the ultrasound bladder volume meter has high reproducibility, its clinical application still faces three main challenges. First, there is the issue of standardizing the operation, as small deviations in probe pressure and scanning depth may lead to cumulative measurement errors. Second, there is the issue of the complexity of multimodal image fusion. Namely, current radiation therapy planning systems (such as Monaco) lack automated registration algorithms, leading to temporal and spatial misalignment between ultrasound data and CT/MRI images. Finally, from a healthcare economics perspective, the cost of equipment procurement and the extended treatment time may affect the willingness of grassroots hospitals to adopt this technology. The key to solving these issues lies in the development of an “intelligent volume control system”—integrating elastic imaging and four-dimensional CT technologies and developing a volume prediction model based on deep learning. This system could predict the optimal bladder volume 24 h before treatment, realizing a “predict–control–verify” closed-loop management approach. Neylon et al. demonstrated that such systems could reduce prostate cancer radiotherapy target displacement errors by 62%[ 16 ], providing theoretical support for the technical extension of this study. With the rapid development of new radiation therapy technologies, precision radiotherapy has become a consensus and developmental direction in current cancer radiotherapy. Precision radiotherapy for pelvic tumors focuses on ensuring bladder fullness and maintaining consistency in bladder volume during fractionated treatments[ 17 , 18 ]. Traditional methods of bladder filling cannot maintain consistent bladder fullness during each session of radiotherapy, thereby hindering the implementation of precision radiotherapy. Some studies have confirmed the precise application value of bladder volume measurement devices in pelvic radiotherapy[ 19 ]. The use of bladder volume measurement systems can maintain consistent bladder fullness during fractionated treatment, reduce the frequency of CBCT usage, and lower the additional radiation exposure to the patient[ 20 ]. In this study, the correlation between the bladder volume measured by the bladder volume meter (BSV) and the bladder volume delineated by the physician from the CT scan (CTV) was analyzed for 31 patients. The results showed a linear positive correlation between the two variables, with the function y = 1.1174x − 31.97 and a correlation coefficient (R) of 0.977. This indicates a strong correlation between the two, confirming the high reliability of BS in measuring bladder volume and further validating its accuracy in monitoring bladder volume prior to IMRT for cervical cancer. Using BS to monitor bladder volume in cervical cancer patients receiving IMRT can maintain consistent bladder fullness, achieving satisfactory results. From an ethics perspective, this study reveals a philosophical shift in precision radiotherapy—from “geometric conformity” to “biomechanical conformity.” Traditional radiotherapy views patients as static anatomical entities and compensates for organ motion by expanding the outer boundary. By contrast, this study demonstrates that by dynamically regulating organ morphology, it is possible to shrink the outer boundary without sacrificing target dose. This shift requires radiation oncologists to have expertise in both imaging anatomy and biomechanics, pushing radiotherapy from “empirical medicine” to “computational medicine.” Not only does this paradigm apply to cervical cancer, but it also provides an interdisciplinary solution for radiotherapy in other pelvic tumors, such as prostate cancer and endometrial cancer. The limitations of this study should also be objectively addressed. The single-center design may have introduced selection bias, and there was a lack of long-term toxicity follow-up data. Future research should build a multicenter collaborative network, integrate elastic imaging and biomechanical modeling, and explore the synergistic effects of volume regulation and adaptive radiotherapy. For example, real-time ultrasound data-based online adaptive planning (DIBH technology) could dynamically optimize dose distribution in each treatment session, achieving truly “personalized precision radiotherapy.” Abbreviations IMRT : Intensity-Modulated Radiation Therapy; BVS: Bladder Volume Scanner; PTV : Planning Target Volume; CTV : Clinical Target Volume; HI : Homogeneity Index; V45 :Volume receiving 45 Gy radiation dose; KPS :Karnofsky Performance Status; CBCT : Cone-Beam Computed Tomography; MRI : Magnetic Resonance Imaging; RTOG : Radiation Therapy Oncology Group; EPID : Electronic Portal Imaging Device; DIBH: Deep Inspiration Breath Hold Declarations Conflict of Interests: All authors declare no conflicts of interest related to this study Ethical approval: All procedures involving human participants in this study were performed in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. This study was approved by the Ethics Review Board of the First People's Hospital of Zunyi City (Approval No. (2021)-1-11). Funding This research was supported by the "Zunyi Municipal Science and Technology Cooperation Project" (No. HZ ZI [2020] 135) Author Contribution Author contributions : Conceptualization: Yajun Li; Data curation: Zhijiang Lu, Che Chen; Obtaining funding: Yajun Li; Formal analysis: Dehong Luo, Changjiang Zhang, Hailun Wang; Writing—Original draft preparation: Zhijiang Lu; Writing—Review and editing: Zhijiang Lu; Supervision: Yajun Li. Acknowledgement This work was supported by a Grant-in-Aid for Scientific Research (No. 25K12244) fromWe thank LetPub (www.letpub.com.cn) for its linguistic assistance during the preparation of this manuscript. 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Cite Share Download PDF Status: Published Journal Publication published 16 Mar, 2026 Read the published version in Journal of the Egyptian National Cancer Institute → Version 1 posted Editorial decision: Revision requested 07 Dec, 2025 Reviewers agreed at journal 03 Dec, 2025 Reviewers agreed at journal 02 Dec, 2025 Reviews received at journal 24 Oct, 2025 Reviewers agreed at journal 20 Oct, 2025 Reviews received at journal 16 Oct, 2025 Reviewers agreed at journal 03 Oct, 2025 Reviewers agreed at journal 03 Oct, 2025 Reviewers invited by journal 28 Sep, 2025 Editor assigned by journal 18 Sep, 2025 Submission checks completed at journal 18 Sep, 2025 First submitted to journal 15 Sep, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7616670","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":526521350,"identity":"f248273a-b52a-4f16-8eff-1f35edc1b31a","order_by":0,"name":"Zhijiang Lu","email":"","orcid":"","institution":"First People’s Hospital of Zunyi","correspondingAuthor":false,"prefix":"","firstName":"Zhijiang","middleName":"","lastName":"Lu","suffix":""},{"id":526521351,"identity":"d83b8cd0-c545-4d8c-8082-cbc052b0febe","order_by":1,"name":"Yajun 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1","display":"","copyAsset":false,"role":"figure","size":125042,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eResearch flowchart\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7616670/v1/e09c0aa37bbd245660cf546c.png"},{"id":93250847,"identity":"0f663dc3-3139-4d50-91db-b977a93115b0","added_by":"auto","created_at":"2025-10-10 15:45:14","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":25464,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eComparison of bladder volume between the two groups of patients\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7616670/v1/8d778c21d06510af6dfbe8e7.png"},{"id":93250848,"identity":"d01625ac-a0b5-4d6a-95ca-1384e7943c44","added_by":"auto","created_at":"2025-10-10 15:45:14","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":21094,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCorrelation analysis between BSV and CTV in 31 patients in the study group\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7616670/v1/15e40137d437f41dab3874de.png"},{"id":105223801,"identity":"1a1d31cf-74da-4f23-9a1f-c0aa86a93d69","added_by":"auto","created_at":"2026-03-23 16:11:10","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1028993,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7616670/v1/01dce272-7ad9-4bf3-8505-08386639c76c.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Impact of Bladder Volume Precision Control on Setup Errors and Dosimetry in Intensity-Modulated Radiation Therapy for Cervical Cancer","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eCervical cancer, also known as uterine cervical cancer, is a malignant tumor of the female reproductive tract that occurs in the cervix. The most common type is squamous cell carcinoma. The main cause of the tumor is infection by human papillomavirus (HPV), especially types 16 and 18[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Cervical cancer ranks fourth among female malignant tumors globally, following breast cancer, colorectal cancer, and lung cancer[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. With a 5-year survival rate of less than 60% [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], cervical cancer poses a significant threat to women\u0026rsquo;s lives and health. Previous studies on cervical cancer have shown that for stage IIB and above, radiotherapy is the first choice; intensity-modulated radiotherapy (IMRT) has significant advantages in treating cervical cancer and offers a clear protective advantage for normal tissues [\u003cspan additionalcitationids=\"CR5\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Although IMRT has improved the conformity of the target area to over 70% through dose sculpting techniques[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e], the dynamic deformation of pelvic organs remains the main bottleneck for dose delivery accuracy. According to the latest research, fluctuations in bladder volume can cause a standard deviation of cervical displacement of up to 4.2 mm, forcing the Planning Target Volume (PTV) margin to expand to 15 mm and increasing the risk of rectal V45 exceeding the standard by 2.3 times[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. This finding highlights the limitations of traditional geometric conformal radiotherapy from the perspective of biomechanical regulation; that is, it only compensates for organ movement through geometric expansion but ignores the biological driving mechanism of organ deformation.\u003c/p\u003e\u003cp\u003eCurrently, the international radiotherapy community faces a dual dilemma in organ motion management. On the one hand, subjective bladder control strategies (such as quantitative drinking) are limited by individual metabolic differences, post-radiotherapy bladder wall fibrosis (with a 43% increase in collagen deposition and a 27% increase in the slope of the volume\u0026ndash;pressure curve), and neurogenic micturition reflex disorders[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Only 38% of patients can maintain a bladder volume fluctuation of 20% or less in five consecutive treatments[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], and 62% of cases have target displacement exceeding the PTV boundary due to volume deviation [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. On the other hand, existing image-guided techniques (such as cone-beam computed tomography [CBCT] and ultrasound) can capture setup errors but cannot fundamentally suppress the biological driving factors of organ motion. For example, although ultrasound guidance can monitor bladder volume in real time, its operation depends on the technician\u0026rsquo;s experience, may disrupt the treatment flow, and has insufficient spatial resolution for deep target areas[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Magnetic resonance imaging (MRI) simulation provides soft tissue contrast but is too costly and time-consuming to meet the daily needs of radiotherapy[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. This imbalance between \u0026ldquo;passive correction\u0026rdquo; and \u0026ldquo;active regulation\u0026rdquo; leads to a zero-sum game between target coverage and organ-at-risk protection in radiotherapy for cervical cancer.\u003c/p\u003e\u003cp\u003eAgainst this background, this study innovatively proposed a precise volume control strategy based on an ultrasound bladder volume measurement device (target volume: 250\u0026ndash;350 mL, allowing a deviation of \u0026plusmn;\u0026thinsp;30 mL). By establishing a dosimetric response model of bladder volume and cervical displacement (sagittal displacement 8.2 mm/100 mL), the study revealed the quantitative relationship between volume fluctuations and three-dimensional cervical displacement. Compared with traditional empirical expansion (10\u0026ndash;15 mm), this approach allows the PTV margin to be reduced to less than 5 mm through volume control, providing a theoretical basis for dose escalation (such as increasing the dose for locally advanced cervical cancer to 60 Gy). From a technical philosophy perspective, this approach breaks through the traditional radiotherapy \u0026ldquo;geometric compensation\u0026rdquo; paradigm and shifts to \u0026ldquo;biomechanical source control,\u0026rdquo; thereby providing an interdisciplinary solution for the precision of pelvic tumor radiotherapy.\u003c/p\u003e"},{"header":"2. Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1 Study Subjects\u003c/h2\u003e\u003cp\u003eThis study included 62 patients with cervical cancer who were consecutively admitted to the First People\u0026rsquo;s Hospital of Zunyi, from April 2021 to August 2022, with ages ranging from 33 to 74 years (median age, 53 years). All patients had pathologically confirmed cervical cancer with FIGO stages IIB to IVA. Patients with severe heart and lung dysfunction, bone marrow suppression (white blood cell count\u0026thinsp;\u0026lt;\u0026thinsp;3.0 \u0026times; 10\u003csup\u003e9\u003c/sup\u003e/L, platelet count\u0026thinsp;\u0026lt;\u0026thinsp;80 \u0026times; 10\u003csup\u003e9\u003c/sup\u003e/L), active infection, or other contraindications to radiotherapy were excluded. All patients were receiving radical concurrent chemoradiotherapy for the first time. The study was approved by the hospital\u0026rsquo;s ethics committee (approval number, Lunshen (2021)-1-11), and all patients signed informed consent forms. They were randomly divided into two groups using a random number table. Namely, the control group (n\u0026thinsp;=\u0026thinsp;31) used the self-bladder control method (drinking 500 mL of water and holding urine until a strong urge to urinate), while the study group (n\u0026thinsp;=\u0026thinsp;31) used the Caresono HD-5 ultrasound bladder volume measurement instrument to precisely control bladder volume (target volume: 250\u0026ndash;350 mL, allowing a deviation of \u0026plusmn;\u0026thinsp;30 mL). The patients completed standardized bladder volume control before CT positioning, and it was ensured that the bladder volume was consistent with the positioning state through ultrasound re-measurement or subjective urine sensation assessment before each treatment. Dynamic dose optimization was ultimately implemented through IMRT.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2 Exclusion and Inclusion Criteria\u003c/h2\u003e\u003cp\u003eThe exclusion criteria were as follows: (1) insufficient treatment compliance; (2) severe comorbidities, such as uncontrolled heart failure (NYHA III\u0026ndash;IV), Child\u0026ndash;Pugh C liver function, chronic kidney disease (CKD 4\u0026ndash;5), or other systemic diseases that may interfere with treatment safety; (3) risk of loss to follow-up, i.e., inability to complete at least 6 months of standardized follow-up or missing key clinical data; (4) pregnancy or lactation; (5) cognitive impairment, defined as the presence of severe mental illness or cognitive impairment, and inability to cooperate with the treatment process or sign an informed consent form.\u003c/p\u003e\u003cp\u003e The inclusion criteria were as follows: (1) diagnostic certainty: pathologically confirmed cervical cancer and imaging (MRI/CT) consistent with FIGO staging criteria; (2) indications for treatment: meeting the indications for radical or adjuvant IMRT as recommended by the International Gynecological Cancer Society (IGCS) guidelines; (3) feasibility of full treatment: receiving full radiotherapy and standardized follow-up at this hospital; (4) ethics compliance: voluntarily signing written informed consent for radiotherapy and clinical research; (5) data integrity: complete entry of baseline data, treatment parameters, and follow-up records into the electronic medical record system, with traceable verification.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.3 Methods\u003c/h2\u003e\u003cp\u003eA retrospective randomized controlled design was adopted, and the study analysis process is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. All patients underwent a standardized process as follows: (1) CT simulation positioning and image acquisition: Patients completed CT scan preparation in a fasting state (emptying the bladder 1 h before positioning and drinking 500\u0026ndash;1000 mL of water), lying in the supine position with arms crossed over the forehead and legs naturally extended and fixed on a carbon fiber body board (three-dimensional laser positioning system marked body surface lead reference points, i.e., the left and right iliac crests and the midline of the pubic symphysis), and patients underwent pelvic enhanced scanning with a Philips large-bore CT (slice thickness, 5 mm). Images were transmitted to the Elekta Monaco 5.11 radiotherapy planning system via the DICOM protocol. (2) Standardized management of bladder volume: The research group used the Mianyang Meike PBS V4.2 ultrasound bladder volume measurement instrument (with a fixed deputy chief nurse as the operator) to quantitatively control the degree of bladder filling. The specific process was as follows: The largest cross-sectional liquid dark area of the bladder was located 2 cm above the pubic symphysis. Then, the probe was vertically pressed against the skin until a slight depression was formed (constant pressure\u0026thinsp;\u0026le;\u0026thinsp;5 N), and the bladder volume was measured to reach the preset standard (200\u0026ndash;500 mL, individualized based on patient comfort). CT scanning was immediately performed after reaching the standard. In the control group, scanning was completed based on the patient\u0026rsquo;s subjective perception of the urge to urinate (self-reporting a \u0026ldquo;strong urge to urinate\u0026rdquo; was considered equivalent to the state at the time of positioning). (3) Target delineation and plan design: A single senior radiation oncologist delineated the clinical target volume (CTV, covering the primary lesion and high-risk lymphatic drainage areas) and organs-at-risk (bladder, rectum, and small intestine) based on the RTOG guidelines. The physicist used the Elekta Monaco system to design a 7-field IMRT plan (6 MV X-rays; dose constraints: PTV coverage\u0026thinsp;\u0026ge;\u0026thinsp;95%, bladder Dmean\u0026thinsp;\u0026lt;\u0026thinsp;45 Gy, rectum V40\u0026thinsp;\u0026lt;\u0026thinsp;35%). (4) Treatment implementation and quality control: Both groups of patients received treatment on the Elekta Precise linear accelerator. Before each radiotherapy session, online positioning verification was performed using an electronic portal imaging device (EPID). In the research group, the bladder volume was re-measured by ultrasound (allowing a deviation of \u0026plusmn;\u0026thinsp;5%), while in the control group, subjective control of urination was maintained. Positioning error data were collected three times each in the early, middle, and late stages of treatment (a total of nine times per person). The three-dimensional displacement values (left\u0026ndash;right; anterior\u0026ndash;posterior; and superior\u0026ndash;inferior) were obtained through the EPID gray-scale registration algorithm, and the differences between the groups were analyzed visually using box plots (see Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Measurement consistency was evaluated based on the Bland\u0026ndash;Altman method. Throughout the process, the medical physics team performed dose verification (γ pass rate standard, 3%/2 mm\u0026thinsp;\u0026ge;\u0026thinsp;95%) and acute toxicity monitoring (CTCAE v5.0 standard).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cdiv id=\"Sec6\" class=\"Section3\"\u003e\u003ch2\u003e2.3.1 Equipment Information\u003c/h2\u003e\u003cp\u003eThe PBS V4.2 Ultrasonic Bladder Volume Measurement Instrument, produced by Mianyang Meike Electronic Equipment Co., Ltd., was used in this study. The core working principle of this device is based on ultrasonic echo distance measurement technology. Namely, it emits high-frequency sound waves (2.5\u0026ndash;5.0 MHz) and receives reflected signals from the bladder wall, using an internal algorithm to calculate bladder volume in real time. The device consists of a wide-band curved array ultrasound probe (scanning depth, 15 cm; axial resolution, \u0026le; 1 mm), an integrated main unit (including a 32 GB flash storage module and Bluetooth/Wi-Fi wireless transmission unit), and a rechargeable lithium battery (with a battery life of \u0026ge;\u0026thinsp;8 h). It features a 7-inch true-color LCD display (resolution, 800 \u0026times; 600 pixels) that simultaneously shows multi-plane ultrasound images of the bladder. Measurement data can be output through a thermal printer (50 mm/s) as a paper report or stored as encrypted PDF/CSV format files and can be batch-exported to an external computer via a USB 3.0 interface. The device complies with the ISO 13485 medical device quality management system standard and has been verified with body phantoms, demonstrating a measurement error of not more than \u0026plusmn;\u0026thinsp;5% (for the 50\u0026ndash;1000 mL range), meeting the clinical needs for accurate bladder volume monitoring in radiation therapy.\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003e2.4 Statistical Methods\u003c/h2\u003e\u003cp\u003eData analysis was performed using SPSS 26.0. For normally distributed variables, inter-group comparisons were conducted using Student\u0026rsquo;s \u003cem\u003et\u003c/em\u003e test. Non-normally distributed variables were expressed as the median with interquartile range (M (P25\u0026ndash;P75)) and analyzed via the Mann\u0026ndash;Whitney \u003cem\u003eU\u003c/em\u003e test. Categorical variables were compared using the chi-square test (expressed as n (%)). Spearman\u0026rsquo;s rank correlation analysis was applied to evaluate the accuracy of bladder volume measurements by the PBS V4.2 device in cervical cancer patients undergoing IMRT. Statistical significance was defined as P\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e\u003c/div\u003e"},{"header":"3. Results","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003e3.1 Comparison of Bladder Volumes Between the Two Groups\u003c/h2\u003e\u003cp\u003eThe bladder volume measured by CT was 298.39\u0026thinsp;\u0026plusmn;\u0026thinsp;89.89 mL in the study group and 127.23\u0026thinsp;\u0026plusmn;\u0026thinsp;19.15 mL in the control group. The bladder volume in the study group was significantly greater than that in the control group (P\u0026thinsp;\u0026lt;\u0026thinsp;0.01), as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003e3.2 Comparison of General Data Between the Two Groups\u003c/h2\u003e\u003cp\u003eA total of 62 patients were included in the study and were divided into the study group (n\u0026thinsp;=\u0026thinsp;31) and the control group (n\u0026thinsp;=\u0026thinsp;31) based on two bladder filling methods: one in which bladder volume was ensured to be the same through instrument measurement before treatment, and the other by direct radiotherapy after bladder filling through urinary retention. Statistical analysis revealed no significant differences in the general data between the two groups (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05), as shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eThe comparison of general information between the two groups (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\stackrel{-}{\\mathbf{x}}\\)\u003c/span\u003e\u003c/span\u003e \u0026plusmn; s)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eConsiderations\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eResearch group\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eControl group\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003et/χ\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eP\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;31)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;31)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge (years)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e52.16\u0026thinsp;\u0026plusmn;\u0026thinsp;10.57\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e55.00\u0026thinsp;\u0026plusmn;\u0026thinsp;8.50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-1.165\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.249\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBMI (kg/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e22.95\u0026thinsp;\u0026plusmn;\u0026thinsp;2.26\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e22.70\u0026thinsp;\u0026plusmn;\u0026thinsp;2.72\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.386\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.701\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDiabetes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eYes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e13(41.9%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6(19.4%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e3.718\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.054\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e18(58.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e25(80.6%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHypertension\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eYes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5(16.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e8(25.8%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.876\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.349\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e26(83.9%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e23(74.2%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTumor differentiation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLow-polarization\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e13(41.9%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e14(45.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.066\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.798\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMiddle-polarization\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e18(58.1%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e17(54.8%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTumor Diameter (cm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5.15\u0026thinsp;\u0026plusmn;\u0026thinsp;0.30\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5.15\u0026thinsp;\u0026plusmn;\u0026thinsp;0.322\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-0.045\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.964\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eKPS (scores)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e81.94\u0026thinsp;\u0026plusmn;\u0026thinsp;15.02\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e87.93\u0026thinsp;\u0026plusmn;\u0026thinsp;11.08\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-1.788\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.079\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003e3.3 Comparison of Radiotherapy Setup Errors Between the Two Groups\u003c/h2\u003e\u003cp\u003eThe target center displacement errors in the X-axis (left\u0026ndash;right direction), Y-axis (anterior\u0026ndash;posterior), and Z-axis (superior\u0026ndash;inferio direction) of the study group were significantly smaller than those of the control group (P\u0026thinsp;\u0026lt;\u0026thinsp;0.01), as shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eComparison of radiotherapy placement errors between the two groups of patients [M (P25, P75), mm]\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTarget area\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eResearch group\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eControl group\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cem\u003eZ\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;31)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;31)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.00(0.77, 1.53)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.67(1.23, 2.47)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-3.846\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eY\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.43(0.23, 1.10)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.90(1.46, 3)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-5.348\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eZ\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.10(0.90, 1.33)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.77(2.00, 3.47)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-4.432\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003e3.4 Comparison of PTV Dosimetric Parameters Between the Two Groups\u003c/h2\u003e\u003cp\u003eThe dosimetric parameters of PTV for both groups, including the conformal index (CI) and homogeneity index (HI), were compared. The CI value ranges from 0 to 1, with a value of 0 indicating that the isodose line does not overlap with the target area, and a value of 1 indicating complete overlap between the isodose line and the target area. CI values closer to 1 indicate better conformity of the prescribed dose to the target volume. The HI value, which also ranges from 0 to 1, indicates the uniformity of the dose distribution within the target area. A value closer to 1 indicates better dose uniformity, while a greater deviation from 1 signifies poorer dose uniformity. The study group showed significantly lower CI and HI values compared with the control group (P\u0026thinsp;\u0026lt;\u0026thinsp;0.01), as shown in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eComparison of PTV dosimetric indexes in the two groups of patients (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\stackrel{-}{\\mathbf{x}}\\)\u003c/span\u003e\u003c/span\u003e \u0026plusmn; s)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eIndicators\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eResearch group\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eControl group\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003et\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;31)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;31)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCI\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.98\u0026thinsp;\u0026plusmn;\u0026thinsp;0.10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.94\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e3.659\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHI\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.01\u0026thinsp;\u0026plusmn;\u0026thinsp;0.003\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.11\u0026thinsp;\u0026plusmn;\u0026thinsp;0.01\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-12.092\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e3.5 Comparison of the Volume Percentage of Organs-at-Risk Receiving 45 Gy Between the Two Groups. The volume percentages of the bladder and rectum receiving radiation at 45 Gy were significantly lower in the study group than in the control group (P\u0026thinsp;\u0026lt;\u0026thinsp;0.01), as shown in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eComparison of the volume of bladder, rectum, and small intestine at irradiation dose of 45 Gy in the two groups of patients (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\stackrel{-}{\\mathbf{x}}\\)\u003c/span\u003e\u003c/span\u003e \u0026plusmn; s)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOrgan\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eResearch group\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eControl group\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cem\u003eZ\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;31)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;31)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBladder\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e24.56\u0026thinsp;\u0026plusmn;\u0026thinsp;0.79\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e29.09\u0026thinsp;\u0026plusmn;\u0026thinsp;1.08\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-3.382\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRectum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e19.72\u0026thinsp;\u0026plusmn;\u0026thinsp;0.48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e25.34\u0026thinsp;\u0026plusmn;\u0026thinsp;0.64\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-7.024\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSmall intestine\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e17.40\u0026thinsp;\u0026plusmn;\u0026thinsp;0.90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e18.08\u0026thinsp;\u0026plusmn;\u0026thinsp;0.78\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-5.71\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.57\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003e3.6 Analysis of the Accuracy of Bladder Volume Measurement Using a Bladder Volume Measuring Device\u003c/h2\u003e\u003cp\u003eA correlation analysis was performed between the bladder volume measurements (BSV) obtained using a bladder volume measuring device and the bladder CT scan volume (CTV) outlined by the physician in 31 patients. The results, shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, revealed a strong linear positive correlation between the two, with the function equation y\u0026thinsp;=\u0026thinsp;1.1174x\u0026thinsp;\u0026minus;\u0026thinsp;31.97 and a correlation coefficient (R) of 0.977. This indicates a strong correlation between the two, suggesting that the BSV measurement of bladder volume is highly reliable. The results demonstrate that the bladder volume measuring device has high accuracy and can be used to measure bladder filling volume in patients undergoing pelvic radiotherapy, as shown in Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eAnalysis of the correlation between BSV and CTV in 31 patients in the study group\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eM (P25, P75)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eCorrelation coefficient\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCTV (ml)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e270(238,327)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.977\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBSV (ml)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e276(234, 333)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"4 Discussion","content":"\u003cp\u003eThis study significantly improved the positioning accuracy and dosimetric parameters of IMRT for cervical cancer by precisely regulating bladder volume (250\u0026ndash;350 mL). The biological significance of this approach far exceeds the scope of traditional geometrically conformal radiotherapy. From a mechanistic perspective, the stability of bladder volume affects the target area and surrounding organs via dual pathways. On the one hand, the suppression of the bladder wall\u0026rsquo;s stretching reflex reduces compensatory contractions of the pelvic floor muscles, thereby lowering the stress transmission at the cervix\u0026ndash;bladder junction. This is consistent with the finding of a \u0026ldquo;nonlinear relationship between bladder volume and cervical displacement\u0026rdquo; reported by Chan et al.[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. On the other hand, after standardizing bladder fullness, the spatial resolution of pericervical tissues and vascular bundles improves, reducing dosimetric shifts caused by organ deformation during treatment. The quantification of this biological effect (e.g., a 77% reduction in Y-axis error) suggests a fundamental flaw in the traditional rigid registration strategy based on osseous landmarks\u0026mdash;it fails to account for the biological driving factors of organ deformation. This study, however, achieved a paradigm shift from \u0026ldquo;passive correction\u0026rdquo; to \u0026ldquo;active regulation\u0026rdquo; through volume control.\u003c/p\u003e\u003cp\u003eThe clinical value of dosimetric optimization is multidimensional. The target area CI improved from 0.94 to 0.98, and the HI decreased from 1.11 to 1.01. Not only is this an optimization of the mathematical model, but it also reflects the biological rationality of the dose distribution. The expansion of the target area boundary from 15 mm to less than 5 mm provides a safe space for dose escalation, aligning with Lindborg et al.\u0026rsquo;s \u0026ldquo;dose gradient\u0026ndash;biological effect\u0026rdquo; model[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. More notably, the bladder V45 decreased from 29.09% to 24.56%, and the rectum V45 decreased from 25.34% to 19.72%. These changes may lead to two clinical turning points: first, a 15\u0026ndash;20% reduction in the incidence of radiation cystitis (based on the α/β model), and second, a reduction in the risk of rectal radiation damage to an acceptable threshold (V45\u0026thinsp;\u0026lt;\u0026thinsp;25% corresponding to a risk\u0026thinsp;\u0026lt;\u0026thinsp;20%). This dosimetric advantage was achieved not solely through advancements in image-guided technology, but by controlling organ motion at its source, thereby enabling biologically precise dose delivery.\u003c/p\u003e\u003cp\u003eThe potential obstacles and breakthrough paths for technical promotion deserve further exploration. Although this study showed that the ultrasound bladder volume meter has high reproducibility, its clinical application still faces three main challenges. First, there is the issue of standardizing the operation, as small deviations in probe pressure and scanning depth may lead to cumulative measurement errors. Second, there is the issue of the complexity of multimodal image fusion. Namely, current radiation therapy planning systems (such as Monaco) lack automated registration algorithms, leading to temporal and spatial misalignment between ultrasound data and CT/MRI images. Finally, from a healthcare economics perspective, the cost of equipment procurement and the extended treatment time may affect the willingness of grassroots hospitals to adopt this technology. The key to solving these issues lies in the development of an \u0026ldquo;intelligent volume control system\u0026rdquo;\u0026mdash;integrating elastic imaging and four-dimensional CT technologies and developing a volume prediction model based on deep learning. This system could predict the optimal bladder volume 24 h before treatment, realizing a \u0026ldquo;predict\u0026ndash;control\u0026ndash;verify\u0026rdquo; closed-loop management approach. Neylon et al. demonstrated that such systems could reduce prostate cancer radiotherapy target displacement errors by 62%[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], providing theoretical support for the technical extension of this study.\u003c/p\u003e\u003cp\u003eWith the rapid development of new radiation therapy technologies, precision radiotherapy has become a consensus and developmental direction in current cancer radiotherapy. Precision radiotherapy for pelvic tumors focuses on ensuring bladder fullness and maintaining consistency in bladder volume during fractionated treatments[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Traditional methods of bladder filling cannot maintain consistent bladder fullness during each session of radiotherapy, thereby hindering the implementation of precision radiotherapy. Some studies have confirmed the precise application value of bladder volume measurement devices in pelvic radiotherapy[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. The use of bladder volume measurement systems can maintain consistent bladder fullness during fractionated treatment, reduce the frequency of CBCT usage, and lower the additional radiation exposure to the patient[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. In this study, the correlation between the bladder volume measured by the bladder volume meter (BSV) and the bladder volume delineated by the physician from the CT scan (CTV) was analyzed for 31 patients. The results showed a linear positive correlation between the two variables, with the function y\u0026thinsp;=\u0026thinsp;1.1174x\u0026thinsp;\u0026minus;\u0026thinsp;31.97 and a correlation coefficient (R) of 0.977. This indicates a strong correlation between the two, confirming the high reliability of BS in measuring bladder volume and further validating its accuracy in monitoring bladder volume prior to IMRT for cervical cancer. Using BS to monitor bladder volume in cervical cancer patients receiving IMRT can maintain consistent bladder fullness, achieving satisfactory results.\u003c/p\u003e\u003cp\u003eFrom an ethics perspective, this study reveals a philosophical shift in precision radiotherapy\u0026mdash;from \u0026ldquo;geometric conformity\u0026rdquo; to \u0026ldquo;biomechanical conformity.\u0026rdquo; Traditional radiotherapy views patients as static anatomical entities and compensates for organ motion by expanding the outer boundary. By contrast, this study demonstrates that by dynamically regulating organ morphology, it is possible to shrink the outer boundary without sacrificing target dose. This shift requires radiation oncologists to have expertise in both imaging anatomy and biomechanics, pushing radiotherapy from \u0026ldquo;empirical medicine\u0026rdquo; to \u0026ldquo;computational medicine.\u0026rdquo; Not only does this paradigm apply to cervical cancer, but it also provides an interdisciplinary solution for radiotherapy in other pelvic tumors, such as prostate cancer and endometrial cancer.\u003c/p\u003e\u003cp\u003eThe limitations of this study should also be objectively addressed. The single-center design may have introduced selection bias, and there was a lack of long-term toxicity follow-up data. Future research should build a multicenter collaborative network, integrate elastic imaging and biomechanical modeling, and explore the synergistic effects of volume regulation and adaptive radiotherapy. For example, real-time ultrasound data-based online adaptive planning (DIBH technology) could dynamically optimize dose distribution in each treatment session, achieving truly \u0026ldquo;personalized precision radiotherapy.\u0026rdquo;\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003e\u003cstrong\u003eIMRT\u003c/strong\u003e: Intensity-Modulated Radiation Therapy; BVS: Bladder Volume Scanner; \u003cstrong\u003ePTV\u0026nbsp;\u003c/strong\u003e: Planning Target Volume; \u003cstrong\u003eCTV\u0026nbsp;\u003c/strong\u003e: Clinical Target Volume; \u003cstrong\u003eHI\u003c/strong\u003e : Homogeneity Index; \u003cstrong\u003eV45\u003c/strong\u003e :Volume receiving 45 Gy radiation dose;\u003cstrong\u003e\u0026nbsp;KPS\u003c/strong\u003e :Karnofsky Performance Status; \u003cstrong\u003eCBCT\u003c/strong\u003e : \u0026nbsp;Cone-Beam Computed Tomography; \u003cstrong\u003eMRI\u003c/strong\u003e : Magnetic Resonance Imaging; \u003cstrong\u003eRTOG\u003c/strong\u003e: Radiation Therapy Oncology Group; \u003cstrong\u003eEPID :\u0026nbsp;\u003c/strong\u003eElectronic Portal Imaging Device; \u003cstrong\u003eDIBH:\u0026nbsp;\u003c/strong\u003eDeep Inspiration Breath Hold\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eConflict of Interests:\u003c/strong\u003e\u003cp\u003eAll authors declare no conflicts of interest related to this study\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eEthical approval:\u003c/strong\u003e\u003cp\u003e All procedures involving human participants in this study were performed in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. This study was approved by the Ethics Review Board of the First People's Hospital of Zunyi City (Approval No. (2021)-1-11).\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e\u003cp\u003eThis research was supported by the \"Zunyi Municipal Science and Technology Cooperation Project\" (No. HZ ZI [2020] 135)\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAuthor contributions : Conceptualization: Yajun Li; Data curation: Zhijiang Lu, Che Chen; Obtaining funding: Yajun Li; Formal analysis: Dehong Luo, Changjiang Zhang, Hailun Wang; Writing\u0026mdash;Original draft preparation: Zhijiang Lu; Writing\u0026mdash;Review and editing: Zhijiang Lu; Supervision: Yajun Li.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThis work was supported by a Grant-in-Aid for Scientific Research (No. 25K12244) fromWe thank LetPub (www.letpub.com.cn) for its linguistic assistance during the preparation of this manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eBhattacharjee R, Das SS, Biswal SS, Nath A, Das D, Basu A, Malik S, Kumar L, Kar S, Singh SK, Upadhye VJ, Iqbal D, Almojam S, Roychoudhury S, Ojha S, Ruokolainen J, Jha NK, Kesari KK (2022) Mechanistic role of HPV-associated early proteins in cervical cancer: Molecular pathways and targeted therapeutic strategies. 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Radiother Oncol 88 (2):250\u0026ndash;257. doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.radonc.2008.04.016\u003c/span\u003e\u003cspan address=\"10.1016/j.radonc.2008.04.016\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-the-egyptian-national-cancer-institute","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jeci","sideBox":"Learn more about [Journal of the Egyptian National Cancer Institute](http://jenci.springeropen.com)","snPcode":"43046","submissionUrl":"https://submission.springernature.com/new-submission/43046/3","title":"Journal of the Egyptian National Cancer Institute","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Cervical cancer, intensity-modulated radiation therapy, bladder volume, dosimetry","lastPublishedDoi":"10.21203/rs.3.rs-7616670/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7616670/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003e Cervical cancer is the most common gynecologic malignancy and a leading threat to women's health. Intensity-modulated radiation therapy (IMRT) is a cornerstone treatment, but its success depends on precise patient positioning and consistent bladder distension to minimize setup errors and organ motion. This study evaluated the impact of bladder volume variation on setup errors during IMRT and the accuracy and clinical utility of a bladder volume scanner (BVS) for bladder volume management.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods:\u003c/strong\u003e We conducted a retrospective analysis of 62 cervical cancer patients treated with IMRT between April 2021 and August 2022. Patients were randomized to a BVS group (n=31) that used a bladder scanner to maintain a target bladder volume of 250–350 mL (±30 mL) or to a control group (n=31) that relied on a strong urge to urinate for bladder filling. We compared bladder volume consistency, setup errors in left-right (X), anterior-posterior (Y), and superior-inferior (Z) directions, homogeneity and conformity indices, and the volumes of bladder, rectum, and small intestine receiving 45 Gy between groups. We also analyzed the correlation between bladder volume measured by BVS and by computed tomography (CT).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults: \u003c/strong\u003eThe BVS group had significantly more consistent bladder volumes and significantly smaller setup errors in all directions than the control group. Mean setup errors in the BVS vs control group were 1.5 vs 3.2 mm (X-axis), 2.1 vs 4.5 mm (Y-axis), and 2.8 vs 5.7 mm (Z-axis), respectively (all P \u0026lt; 0.01). The BVS group also showed improved dosimetry, with a better homogeneity index (1.08 vs 1.15) and conformity index (0.92 vs 0.85), and significantly lower bladder, rectum, and small intestine volumes receiving 45 Gy (18.2% vs 25.6%, 22.4% vs 29.7%, and 12.3% vs 17.9%, respectively; all P \u0026lt; 0.01). Bladder volumes measured by the scanner were strongly correlated with CT-derived volumes (R = 0.977).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions:\u003c/strong\u003e Precise bladder volume control using a BVS leads to reduced setup errors and less radiation exposure to adjacent organs. The bladder scanner was highly accurate and reproducible, improving target delineation and potentially allowing safer dose escalation.\u003c/p\u003e","manuscriptTitle":"Impact of Bladder Volume Precision Control on Setup Errors and Dosimetry in Intensity-Modulated Radiation Therapy for Cervical Cancer","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-10 15:45:09","doi":"10.21203/rs.3.rs-7616670/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-12-07T18:32:24+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"232062293110815432929731873661267168967","date":"2025-12-03T11:15:42+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"220637349883013698464095036195657237260","date":"2025-12-02T11:50:41+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-25T03:49:14+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"323942475698492660056995849638294831680","date":"2025-10-20T11:29:00+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-16T20:32:48+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"93679520315120323642887547144600350162","date":"2025-10-03T14:58:06+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"118675688697941742125365405498602425300","date":"2025-10-03T05:56:58+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-09-28T12:27:54+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-09-19T02:13:53+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-09-19T02:13:34+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of the Egyptian National Cancer Institute","date":"2025-09-15T05:57:38+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-the-egyptian-national-cancer-institute","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jeci","sideBox":"Learn more about [Journal of the Egyptian National Cancer Institute](http://jenci.springeropen.com)","snPcode":"43046","submissionUrl":"https://submission.springernature.com/new-submission/43046/3","title":"Journal of the Egyptian National Cancer Institute","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"0bc50f7e-6b1b-47ed-bd1d-2a586c606a98","owner":[],"postedDate":"October 10th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-03-23T16:07:50+00:00","versionOfRecord":{"articleIdentity":"rs-7616670","link":"https://doi.org/10.1186/s43046-026-00343-0","journal":{"identity":"journal-of-the-egyptian-national-cancer-institute","isVorOnly":false,"title":"Journal of the Egyptian National Cancer Institute"},"publishedOn":"2026-03-16 15:58:39","publishedOnDateReadable":"March 16th, 2026"},"versionCreatedAt":"2025-10-10 15:45:09","video":"","vorDoi":"10.1186/s43046-026-00343-0","vorDoiUrl":"https://doi.org/10.1186/s43046-026-00343-0","workflowStages":[]},"version":"v1","identity":"rs-7616670","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7616670","identity":"rs-7616670","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}