A novel free-assembled template for interstitial brachytherapy of locally advanced cervical cancer: a dosimetric study

A novel free-assembled template for interstitial brachytherapy of locally advanced cervical cancer: a dosimetric study | 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 A novel free-assembled template for interstitial brachytherapy of locally advanced cervical cancer: a dosimetric study Ranxi Liang, Jie Zhu, Qian Peng, Jiabao Ma, Dandan Huang, Bin Bi, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8657825/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 9 You are reading this latest preprint version Abstract Background The application of guidance template in interstitial brachytherapy (ISBT) was expected to improve target coverage and sparing organs at risk for locally advanced cervical cancer (LACC). The purpose of this study was to compare dosimetric and procedural outcomes of template-guided ISBT against free-handed ISBT. Methods Consecutive patients with LACC were prospectively enrolled at Sichuan Cancer Hospital from February to September 2025. A novel 3D-printed free-assembled interstitial template (FAIT), featuring a tandem with optimized non-coplanar needle channels, was invented and utilized for ISBT. Each patient underwent both FAIT-guided and free-handed high-dose-rate ISBT within 3 days with a random sequence. Treatment plans were generated in the Oncentra planning system with a 600 cGy prescription, and dosimetric parameters including high-risk clinical target volume (HRCTV) D 90 , dose of organs at risk (OARs) (D 1cc and D 2cc for bladder, rectum, sigmoid and bowel) were extracted. The number of interstitial needles and implantation time were also recorded. Data were presented as mean ± standard deviation and compared using paired Student’s t -tests. Statistical significance was defined as P < 0.05. Results 55 patients received both FAIT-guided and free-handed ISBT procedures after pelvic external beam radiotherapy (EBRT) of 45-50.4 Gy with 25–28 fractions. Most patients were stage ⅡB (n = 34, 61.8%) and squamous cell carcinoma (n = 49, 89.1%), and mean post-EBRT HRCTV volume was 61.8 ± 21.3 cm 3 . There was no significant difference on the number of needles used in FAIT-guided and free-handed ISBTs (4.88 ± 0.90 vs. 4.76 ± 1.24, P = 0.30). FAIT guidance shortened implantation time (5.83 ± 1.93 vs 8.03 ± 2.71 min, P < 0.0001) and achieved higher HRCTV D90 (611.38 ± 35.12 vs 580.86 ± 64.65 cGy, P 0.05). Conclusions Improved target volume dose coverage and shortened needle implantation time were achieved with the application of the novel 3D-printed FAIT in ISBT. This novel template had high clinical utility and was worthy of further promotion and application. Locally advanced cervical cancer interstitial brachytherapy guidance template dosimetry Figures Figure 1 Figure 2 Figure 3 Background Cervical cancer remains a major global health burden, with a substantial proportion of patients presenting with locally advanced disease.[ 1 ] For locally advanced cervical cancer (LACC), the current standard of care comprises external beam radiotherapy (EBRT) with concurrent platinum-based chemotherapy followed by brachytherapy (BT).[ 2 ] Image-guided adaptive brachytherapy has demonstrably improved dose escalation to tumor while reducing doses to OARs, thereby enhancing local control and toxicity profiles.[ 3 ] Nevertheless, LACC often exhibits large volumes, irregular morphology, and parametrial extension, which limit adequate coverage with intracavitary brachytherapy (ICBT) alone.[ 4 ]To overcome these limitations, interstitial brachytherapy (ISBT), combining intracavitary applicators with interstitial needles, has been adopted to improve dose conformality and margin coverage.[ 5 , 6 ] Template-based hybrid applicators (e.g., tandem-needle systems) facilitate straight and oblique needle insertions and have been reported to improve operability and dosimetric performance in cases with bulky tumors.[ 7 ] Perineal template-based approaches, such as the US Food and Drug Administration (FDA)-approved Venezia™ applicator (Elekta, Stockholm, Sweden), are commonly used. As a hybrid applicator combining a tandem with needle-capable ovoids, the Venezia™ facilitates straight and oblique needle insertion in a single, pre-assembled system, reported to improve operability, precision, and early clinical outcomes.[ 8 , 9 ] However, off-the-shelf applicators may not adequately accommodate regional anatomical variation, and reliance on free-handed implantation or institution-specific devices impedes standardization and reproducibility.[ 10 ] To address these gaps, we designed a novel 3D-printed free-assembled interstitial template (FAIT) (Chinese Invention Patent No. 201910458672.X) featuring a central tandem and radially distributed, non-coplanar channels with selectable angulations (Fig. 1 a). The purpose of this prospective study was to evaluate dosimetric and procedural advantages of the novel template in ISBT, and further clarify its clinical potential and application prospects. Methods Study population Consecutive patients with LACC treated at Sichuan Cancer Hospital (Chengdu, China) between February 2025 and September 2025 were prospectively screened. This study was approved by the Ethics Committee for Medical Rescarch and New Medical Technology of Sichuan Cancer Hospital (SCCHEC-02-2025-111), and performed in accordance with the principles of the Declaration of Helsinki. The informed consent form was acquired from each patient prior to BT, and all patient data were de-identified. The inclusion criteria were: (1) aged 18 to 75 years; (2) pathologically confirmed cervical cancer; (3) locally advanced stage with IIB, IIIA, IIIB, IIIC, or IVA, according to the International Federation of Gynecology and Obstetrics (FIGO) staging of cancer of the cervix uteri 2018;[ 11 ] (4) pelvic intensity-modulated EBRT dose 45–50.4 Gy with 23–28 fractions; (5) consecutive and longitudinal contrast-enhanced pelvic magnetic resonance imaging (MRI) at 2 time points: before EBRT, after the 20th fraction of EBRT and prior to BT; (6) BT performed within 1 week after EBRT; (7) fitted and voluntary to ISBT under general anesthesia; (8) adequate renal, hepatic, and bone marrow functions. Patients were enrolled only if they met all eligibility criteria. Patients were excluded if they met any of the following criteria: (1) age 75 years old; (2) FIGO 2018 stage with I, IIA, or IVB; (3) palliative treatment purpose; (4) pelvic relapse after initial treatment; (4) absence or incomplete pelvic MRI; (5) refuse or unsuitable to ISBT; (6) delayed BT, performed more than 1 week after EBRT. The novel 3D-printed FAIT The novel 3D-printed FAIT featured an elliptical-section vaginal applicator with a central hollow and four replaceable needle-guiding channels. The channels aligned along the short axis permitted anterior-posterior needle trajectories. Along the long axis, the four replaceable channels could support angulations of 0°, 5°, 10°, or 15°, which could be selected independently to extend lateral parametrial coverage (Fig. 1 a). For vaginal applicator, the central channel accommodated the tandem-based BT (tandem and/or interstitial needles). For LACC involving parametrial infiltration or bulky disease, replaceable channels with 10° or 15° angulations were recommended to optimize radiation dose distribution at the tumor margins. (Fig. 1 b and 1 c). The 3D-printed FAIT device, which was manufactured by Sichuan Farsoon Turing Additive Manufacturing Co., Ltd. using biocompatible materials, was protected under Chinese patent law (Chinese Invention Patent No. 201910458672.X) and was registered with the National Medical Products Administration (Sichuan Medical Device Registration No. 20252050191). ISBT procedure A total of 5 BT fractions, each prescribed to a dose of 600 cGy, were administered to patients with LACC over a 3-week period. During the BT course, patients received free-handed and FAIT-guided ISBT fractions within 3 days in a randomized sequence. Interstitial needle implantation. Following general anesthesia, patients underwent vaginal and perineal disinfection, urinary catheter insertion, and interstitial needle implantation. Needle implantation was performed under real-time transabdominal or transrectal ultrasound guidance. For free-handed ISBT, needle implantation was performed without a guidance template; whereas the novel 3D-printed template was utilized for the FAIT-guided ISBT. The number of needles, along with the insertion angles and depths, was predetermined through consensus by three experienced radiation oncologists (Z.J., P.Q., and Y.G.S.), who also performed all implantation procedures. In the treatment of an individual patient, one radiation oncologist performed both the free-handed and FAIT-guided implantations. Following each implantation, necessary adjustments to the needle positions were made based on the review and recommendations of the other two oncologists. Contouring . After the completion of interstitial needle implantation, patients were allowed to recover from anesthesia before being transferred to computed tomography (CT) simulation. The bladder was filled with 100 mL of normal saline, and CT images were acquired with a slice thickness of 3 mm. Delineation of OARs was performed according to the recommendations of the Groupe Européen de Curiethérapie-European Society for Therapeutic Radiology and Oncology (GEC-ESTRO) and International Commission on Radiation Units and Measurement (ICRU) Report 89.[ 12 – 15 ]The high-risk clinical target volume (HRCTV) was contoured on CT images by integrating findings from clinical examination and pre-BT MRI. The OARs included the bladder, rectum, sigmoid, and bowel. All contouring was performed using the Elekta Oncentra 3D treatment planning system (Elekta AB, Stockholm, Sweden). To minimize inter-observer variability and mitigate potential bias, HRCTV and OARs were initially delineated by a single experienced radiation oncologist (M.J.B., H.D.D., or T.Y.) and subsequently reviewed and modified, if necessary, by the other two radiation oncologists. Planning and treatment. Following contouring, implanted needle reconstruction was performed manually by the brachytherapy dosimetrist (L.R.X. and B.B.). Treatment plans were subsequently optimized using the Inverse Planning Simulated Annealing (IPSA) algorithm, with manual finetuning applied if necessary. All ISBT plans were reviewed and approved by experienced radiation oncologists (M.J.B., H.D.D., and T.Y.). Patients received high-dose-rate (HDR) ISBT by 192 Ir source. The prescribed dose per ISBT fraction was HRCTV D 90 600 cGy. Dose constraints for OARs adhered to GEC-ESTRO recommendations: bladder D 2cc < 8500 cGy; and rectum, sigmoid, and bowel D 2cc < 7500 cGy.[ 12 , 13 ] Statistical analysis Patients’ clinical and pathological characteristics were were incorporated into the data set. Implantation time and dosimetric parameters for each ISBT fraction were recorded. Statistical analyses were performed using SPSS Statistics, Version 23 (IBM Corp., Armonk, NY, USA). Continuous data were presented as mean ± standard deviation (SD). Paired Student's t -tests were used to assess differences between groups, with statistical significance defined as P < 0.05. Results Patient characteristics Consecutive patients with LACC treated at Sichuan Cancer Hospital between between February and September 2025 were propectively screened for potential inclusion. Of the 100 patients screened, 55 patients with LACC met eligibility criteria and underwent both free-handed and FAIT-guided ISBT procedures (Fig. 2 ). The median age of the included patients was 56 years (range, 33–75). The majority of patients had clinical stage IIB disease (n = 34, 61.8%), squamous cell carcinoma (SCC) histology (n = 49, 89.1%), and received concurrent chemotherapy (n = 51, 92.7%). All patients receiced pelvic EBRT 45 ~ 50.4 Gy with conventional fractions, of which 16 (29.1%) received extended-field radiation to para-aortic nodal drainage area and and 25 (45.5%) received lymph node boost to 55 ~ 61.6 Gy. The average volume of HRCTV after EBRT was 61.8 ± 21.3 cm 3 . (Table 1 ). Table 1 Clinicopathological characteristics of patients with LACC. Characteristic Total (n = 55) n (%) Age Median 56 (range, 33–75) < 60 38 (69.1) ≥ 60 17 (30.9) Clinical stage (FIGO 2018) Ⅰ-Ⅱ 34 (61.8) Ⅲ-Ⅳ 21 (38.2) Histology SCC 49 (89.1) Other 6 (10.9) Pelvic EBRT dose 45 ~ 50.4 Gy 30 (54.5) 45 ~ 50.4 Gy with LN boost 25 (45.5) Extended-filed radiation Yes 16 (29.1) No 39 (70.9) Concurrent chemotherapy Yes 51 (92.7) No 4 (7.3) HRCTV (cm 3 ) Average 61.8 ± 21.3 First ISBT procedure Free-handed 28 (50.9) Template-guided 27 (49.1) ISBT dosimetric outcomes The ISBT procedure was performed without complications such as needle penetration into the bladder or rectum, or implantation-related major vaginal bleeding. There was no significant diffrence on the number of interstitial needles between FAIT-guided and free-handed ISBT (4.88 ± 0.90 vs. 4.76 ± 1.24; P = 0.30). Implantation time was significantly shortened in FAIT-guided ISBT compared with free-handed ISBT (5.83 ± 1.93 vs. 8.03 ± 2.71 min; P < 0.0001) (Fig. 3 a–b). The volume of HRCTV in FAIT-guided ISBT and free-handed ISBT was 62.48 ± 20.92 and 61.20 ± 21.81 cm 3 , respectively, with no significant diffrence ( P = 0.66) (Fig. 3 c). Dose of HRCTV D 90 FAIT-guided ISBT was significantly higher than free-handed ISBT (611.38 ± 35.11 vs. 580.86 ± 64.65 cGy, P < 0.0001) (Fig. 3 d). As for dosimetric restrictions of OARs (Fig. 3 e and f), D 2cc and D 1cc for bladder (D 2cc 433.38 ± 22.84 vs. 435.70 ± 28.22 cGy, P = 0.42; D 1cc 456.27 ± 19.03 vs. 463.11 ± 24.40 cGy, P = 0.01), rectum (D 2cc 383.34 ± 38.67 vs. 379.13 ± 42.17 cGy, P = 0.42; D 1cc 419.30 ± 36.86 vs. 415.76 ± 41.59 cGy, P = 0.48 ), sigmoid (D 2cc 335.79 ± 60.54 vs. 325.29 ± 84.83 cGy, P = 0.27; D 1cc 372.34 ± 57.06 vs. 362.34 ± 88.77 cGy, P = 0.27), and bowel (D 2cc 324.08 ± 68.45 vs. 325.86 ± 79.38 cGy, P = 0.85; D 1cc 357.42 ± 65.32 vs. 357.69 ± 83.48 cGy, P = 0.98) were very close in FAIT-guided and free-handed ISBTs, with no significant differences for D 2cc of all OARs ( P > 0.05). Discussion This single-center, prospective, self-controlled study demonstrated that the novel template FAIT improved target volume dose coverage and shortened needle implantation time in ISBT. It’s non‑coplanar, multi‑angle, modular channels design facilitated reproducible placements of lateral and parametrial needles. This capability improved margin coverage in bulky tumors with parametrial infiltration and supported procedural standardization across operators. Furthermore, the application of 3D-printed FAIT enhanced procedural efficiency under general anesthesia and might facilitate the performance of ISBT by less experienced BT oncologists. Given its high practicality and effectiveness in optimizing treatment delivery, the novel template FAIT addressed a critical need. These advantages supported its active promotion for widespread adoption in routine ISBT practice. Our institute was a high-volume tertiary hospital in western China, and members of the ISBT team were highly experienced in free-handed interstitial implantation. Despite the fact that most patients with LACC in this study had bulky tumors with mean HRCTV volume exceeding 60 cm 3 , nearly optimal HRCTV D 90 dose coverage was consistently achieved using free-handed implantation under real-time transabdominal or transrectal ultrasound guidance. Cumulative radiation dose to HRCTV was strongly associated with local tumor control and overall survival (OS) in LACC. Inadequate dose coverage at the tumor margin, parametrial region, or pelvic sidewall would significantly increase the risk of pelvic recurrence. With the assistance of 3D-printed FAIT, HRCTV dose coverage was further improved without increasing the risk of perforation to pelvic OARs. Moreover, the narrow standard deviation of HRCTV D 90 observed in the FAIT group underscored its superior procedural reproducibility and dosimetric consistency. Importantly, the improved procedural efficiency after the application of FAIT template led to a significant reduction in operation time, thereby alleviating operator’s concerns regarding potential injury to the bladder and rectum during needle insertion. Our findings were consistent with previously reported trends in literatures, supporting the notion that anatomy-driven needle channel planning improved target coverage and OAR sparing[ 16 , 17 ]. The results further underscored the pivotal role of 3D printing in overcoming dosimetric challenges in cases with complex anatomy.[ 18 ] Consistent with early reports[ 19 – 21 ], the FAIT approach improved procedural consistency and efficiency through template-guided implantation. Notably, unlike strategies that emphasized either fully customized applicators or pure modular designs[ 22 – 24 ], the structure of FAIT occupied a strategic middle ground by integrating the strengths of both paradigms. It circumvented the need for sophisticated algorithms and specialized infrastructure associated with fully patient-specific solutions, while offering greater flexibility and precision in needle placement through its multi-angle channel configuration. This hybrid design enhanced both clinical accessibility and adaptability in routine ISBT practice. This study had several limitations. First, the present study was limited by a short follow-up period, which precluded the evaluation of local tumor control and late radiation-related toxicities. Second, the present workflow mainly relied on manual needle-path planning without the integration of advanced computational tools. Future studies could expand enrollment, prolong follow-up to capture mature clinical outcomes, and investigate the synergistic potential of combining the FAIT template with automated or artificial intelligence-driven needle-path optimization systems to further improve target coverage and enhance OAR sparing. In conclusion, the 3D-printed FAIT, which synergistically integrated personalized multi-angle needle guidance with modular standardization to achieve superior dosimetry, enhanced target volume coverage while sparing OARs, and improved procedural efficiency in ISBT for LACC. By bridging the gap between customization and reproducibility, the novel template FAIT held transformative potential to democratize high-quality ISBT. Declarations Ethics approval and consent to participate: This study was approved by the Ethics Committee for Medical Rescarch and New Medical Technology of Sichuan Cancer Hospital (SCCHEC-02-2025-111), and performed in accordance with the principles of the Declaration of Helsinki. The informed consent form was acquired from each patient prior to BT, and all patient data were de-identified. Competing interests The authors declare that they have no conflicts of interest. Consent for publication Not applicable. Data availability The data that support the findings of this study are available from the corresponding author upon reasonable request. Employment or leadership None declared. Contributions (I) Conception and design: L.S., T.Y. and W.X.L. (Ⅱ) Acquisition of data: B.B., T.T., and M.J.B. (Ⅲ) Analysis and interpretation of data: L.R.X., Z.J. and P.Q. (IV)Manuscript writing: L.R.X., Z.J. and P.Q. (V) Revision of the manuscriptdraf: Z.J. H.D.D., Y.G.S. and P.Q. (Ⅵ) Administrative support and study supervision or coordination: all authors. (Ⅶ)Final approval of manuscript: all authors. Acknowledgments The authors would like to thank Professor Jingyi Lang and Professor Shichuan Zhang, Department of Radiation Oncology, Precision Radiation in Oncology Key Laboratory of Sichuan Province, Sichuan Clinical Research Center for Cancer, Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, University of Electronic Science and Technology of China, Chengdu, China, for their suggestions in study conception. All FAIT templates were donated by Sichuan Farsoon Turing Additive Manufacturing Co., Ltd. for free use. Funding This work was supported by Health Commission of Sichuan Province Medical Science and Technology Program (24LCYJZD07) and Science and Technology Department of Sichuan Province (2026NSFSC1908). References Siegel RL, Kratzer TB, Giaquinto AN, Sung H, Jemal A. Cancer statistics, 2025. Ca. 2025;75(1):10. https://doi.org/10.3322/caac.21871 . 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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-8657825","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":593089728,"identity":"aadd4436-b989-4140-9e81-5e6786fb2ee3","order_by":0,"name":"Ranxi Liang","email":"","orcid":"","institution":"Sichuan Cancer Hospital \u0026 Institute","correspondingAuthor":false,"prefix":"","firstName":"Ranxi","middleName":"","lastName":"Liang","suffix":""},{"id":593089730,"identity":"17ce1432-90e1-4208-8e96-a6fa01bfdb9e","order_by":1,"name":"Jie Zhu","email":"","orcid":"","institution":"Sichuan Cancer Hospital \u0026 Institute","correspondingAuthor":false,"prefix":"","firstName":"Jie","middleName":"","lastName":"Zhu","suffix":""},{"id":593089734,"identity":"b1396cc8-35ec-4481-a5f0-42855d0fe9b1","order_by":2,"name":"Qian Peng","email":"","orcid":"","institution":"Sichuan Cancer Hospital \u0026 Institute","correspondingAuthor":false,"prefix":"","firstName":"Qian","middleName":"","lastName":"Peng","suffix":""},{"id":593089735,"identity":"dddccb85-703f-4cad-b204-2ed43186625c","order_by":3,"name":"Jiabao Ma","email":"","orcid":"","institution":"Sichuan Cancer Hospital \u0026 Institute","correspondingAuthor":false,"prefix":"","firstName":"Jiabao","middleName":"","lastName":"Ma","suffix":""},{"id":593089737,"identity":"e71c900a-b6ef-4313-b36a-c6109f9939bd","order_by":4,"name":"Dandan Huang","email":"","orcid":"","institution":"Sichuan Cancer Hospital \u0026 Institute","correspondingAuthor":false,"prefix":"","firstName":"Dandan","middleName":"","lastName":"Huang","suffix":""},{"id":593089738,"identity":"e4245160-1a31-4330-bbf4-eeb45ae80f8e","order_by":5,"name":"Bin Bi","email":"","orcid":"","institution":"Sichuan Cancer Hospital \u0026 Institute","correspondingAuthor":false,"prefix":"","firstName":"Bin","middleName":"","lastName":"Bi","suffix":""},{"id":593089739,"identity":"088283a4-4987-466f-8f60-f240ef44c9e6","order_by":6,"name":"Ting Tang","email":"","orcid":"","institution":"Sichuan Cancer Hospital \u0026 Institute","correspondingAuthor":false,"prefix":"","firstName":"Ting","middleName":"","lastName":"Tang","suffix":""},{"id":593089740,"identity":"0c1dfe1c-7a62-433c-b4ee-ad19dd845405","order_by":7,"name":"Shun Lu","email":"","orcid":"","institution":"Sichuan Cancer Hospital \u0026 Institute","correspondingAuthor":false,"prefix":"","firstName":"Shun","middleName":"","lastName":"Lu","suffix":""},{"id":593089741,"identity":"9489eb92-e20e-47da-9dfb-a5907bf8b163","order_by":8,"name":"Gaoshu Yan","email":"","orcid":"","institution":"Sichuan Cancer Hospital \u0026 Institute","correspondingAuthor":false,"prefix":"","firstName":"Gaoshu","middleName":"","lastName":"Yan","suffix":""},{"id":593089742,"identity":"93abf597-6224-47da-9f82-91de684080d9","order_by":9,"name":"Xianliang Wang","email":"","orcid":"","institution":"Sichuan Cancer Hospital \u0026 Institute","correspondingAuthor":false,"prefix":"","firstName":"Xianliang","middleName":"","lastName":"Wang","suffix":""},{"id":593089743,"identity":"a86926e8-cea8-459c-b4a2-fcf64294cc55","order_by":10,"name":"Yan Tan","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAy0lEQVRIiWNgGAWjYFADCeYDBz78IEIhD0ILW+LBmT2kaeExPszBRoQWe/azxyR+7qiT55/d8+Ew0AR5frEDBGzhyUuT7D1z2HDGnbMbDhdYMBjOnJ1AyGE5ZhK8bQcSDCRyNxyewcOQYHCbkBb+N2aSf9vqgFpyHhzmYSNGi0SOmTRvGzNICwORWm68MbaWbQP65UaaATCQJQj7hb0/x/Dm2zZgiM1Ifvzhww8beX5pAlqAgEUCiSOBUxkyYP5AlLJRMApGwSgYuQAAaxZBhVySxKkAAAAASUVORK5CYII=","orcid":"","institution":"Sichuan Cancer Hospital \u0026 Institute","correspondingAuthor":true,"prefix":"","firstName":"Yan","middleName":"","lastName":"Tan","suffix":""}],"badges":[],"createdAt":"2026-01-21 09:38:37","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8657825/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8657825/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":103165291,"identity":"c9519b79-0023-4c7e-80c8-cb385f46bf1e","added_by":"auto","created_at":"2026-02-22 12:25:33","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":24690986,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Schematic diagram of the 3D‑printed FAIT; (b and c) Dose distributions in FAIT-guided ISBT.\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-8657825/v1/59e35cf219f6328077afd343.png"},{"id":103165289,"identity":"52b2690c-bee6-46ff-bd13-aa9509f45530","added_by":"auto","created_at":"2026-02-22 12:25:33","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":593477,"visible":true,"origin":"","legend":"\u003cp\u003eFlow chart showing the screening process for enrolled individuals.\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-8657825/v1/b3122b5661fde0d36ebc3024.png"},{"id":103165290,"identity":"97bef1f1-6b20-4827-a67e-1396b6fe8395","added_by":"auto","created_at":"2026-02-22 12:25:33","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":2636602,"visible":true,"origin":"","legend":"\u003cp\u003eComparisons of (a) the number of interstitial needles, (b) needle implantation time, (c) volume of HRCTV, (d) HRCTV D\u003csub\u003e90\u003c/sub\u003e, (e) D\u003csub\u003e2cc\u003c/sub\u003e for OARs, and (f) D\u003csub\u003e1cc\u003c/sub\u003e for OARs in FAIT-guided ISBT and free-handed ISBT.\u003c/p\u003e","description":"","filename":"Figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-8657825/v1/dbb81b5a68b3068f410ec94c.png"},{"id":103504657,"identity":"b6bc7919-cc16-4ada-9c8c-76249b80ecc9","added_by":"auto","created_at":"2026-02-26 13:20:55","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":20620118,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8657825/v1/8ec9424c-29b1-4fcc-a310-a026ed75fdcf.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"A novel free-assembled template for interstitial brachytherapy of locally advanced cervical cancer: a dosimetric study","fulltext":[{"header":"Background","content":"\u003cp\u003eCervical cancer remains a major global health burden, with a substantial proportion of patients presenting with locally advanced disease.[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] For locally advanced cervical cancer (LACC), the current standard of care comprises external beam radiotherapy (EBRT) with concurrent platinum-based chemotherapy followed by brachytherapy (BT).[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] Image-guided adaptive brachytherapy has demonstrably improved dose escalation to tumor while reducing doses to OARs, thereby enhancing local control and toxicity profiles.[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] Nevertheless, LACC often exhibits large volumes, irregular morphology, and parametrial extension, which limit adequate coverage with intracavitary brachytherapy (ICBT) alone.[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]To overcome these limitations, interstitial brachytherapy (ISBT), combining intracavitary applicators with interstitial needles, has been adopted to improve dose conformality and margin coverage.[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eTemplate-based hybrid applicators (e.g., tandem-needle systems) facilitate straight and oblique needle insertions and have been reported to improve operability and dosimetric performance in cases with bulky tumors.[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] Perineal template-based approaches, such as the US Food and Drug Administration (FDA)-approved Venezia\u0026trade; applicator (Elekta, Stockholm, Sweden), are commonly used. As a hybrid applicator combining a tandem with needle-capable ovoids, the Venezia\u0026trade; facilitates straight and oblique needle insertion in a single, pre-assembled system, reported to improve operability, precision, and early clinical outcomes.[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] However, off-the-shelf applicators may not adequately accommodate regional anatomical variation, and reliance on free-handed implantation or institution-specific devices impedes standardization and reproducibility.[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eTo address these gaps, we designed a novel 3D-printed free-assembled interstitial template (FAIT) (Chinese Invention Patent No. 201910458672.X) featuring a central tandem and radially distributed, non-coplanar channels with selectable angulations (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea). The purpose of this prospective study was to evaluate dosimetric and procedural advantages of the novel template in ISBT, and further clarify its clinical potential and application prospects.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy population\u003c/h2\u003e \u003cp\u003eConsecutive patients with LACC treated at Sichuan Cancer Hospital (Chengdu, China) between February 2025 and September 2025 were prospectively screened. This study was approved by the Ethics Committee for Medical Rescarch and New Medical Technology of Sichuan Cancer Hospital (SCCHEC-02-2025-111), and performed in accordance with the principles of the Declaration of Helsinki. The informed consent form was acquired from each patient prior to BT, and all patient data were de-identified.\u003c/p\u003e \u003cp\u003eThe inclusion criteria were: (1) aged 18 to 75 years; (2) pathologically confirmed cervical cancer; (3) locally advanced stage with IIB, IIIA, IIIB, IIIC, or IVA, according to the International Federation of Gynecology and Obstetrics (FIGO) staging of cancer of the cervix uteri 2018;[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] (4) pelvic intensity-modulated EBRT dose 45\u0026ndash;50.4 Gy with 23\u0026ndash;28 fractions; (5) consecutive and longitudinal contrast-enhanced pelvic magnetic resonance imaging (MRI) at 2 time points: before EBRT, after the 20th fraction of EBRT and prior to BT; (6) BT performed within 1 week after EBRT; (7) fitted and voluntary to ISBT under general anesthesia; (8) adequate renal, hepatic, and bone marrow functions. Patients were enrolled only if they met all eligibility criteria.\u003c/p\u003e \u003cp\u003ePatients were excluded if they met any of the following criteria: (1) age\u0026thinsp;\u0026lt;\u0026thinsp;18 or \u0026gt;\u0026thinsp;75 years old; (2) FIGO 2018 stage with I, IIA, or IVB; (3) palliative treatment purpose; (4) pelvic relapse after initial treatment; (4) absence or incomplete pelvic MRI; (5) refuse or unsuitable to ISBT; (6) delayed BT, performed more than 1 week after EBRT.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eThe novel 3D-printed FAIT\u003c/h3\u003e\n\u003cp\u003eThe novel 3D-printed FAIT featured an elliptical-section vaginal applicator with a central hollow and four replaceable needle-guiding channels. The channels aligned along the short axis permitted anterior-posterior needle trajectories. Along the long axis, the four replaceable channels could support angulations of 0\u0026deg;, 5\u0026deg;, 10\u0026deg;, or 15\u0026deg;, which could be selected independently to extend lateral parametrial coverage (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea). For vaginal applicator, the central channel accommodated the tandem-based BT (tandem and/or interstitial needles). For LACC involving parametrial infiltration or bulky disease, replaceable channels with 10\u0026deg; or 15\u0026deg; angulations were recommended to optimize radiation dose distribution at the tumor margins. (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb and \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec).\u003c/p\u003e \u003cp\u003eThe 3D-printed FAIT device, which was manufactured by Sichuan Farsoon Turing Additive Manufacturing Co., Ltd. using biocompatible materials, was protected under Chinese patent law (Chinese Invention Patent No. 201910458672.X) and was registered with the National Medical Products Administration (Sichuan Medical Device Registration No. 20252050191).\u003c/p\u003e\n\u003ch3\u003eISBT procedure\u003c/h3\u003e\n\u003cp\u003eA total of 5 BT fractions, each prescribed to a dose of 600 cGy, were administered to patients with LACC over a 3-week period. During the BT course, patients received free-handed and FAIT-guided ISBT fractions within 3 days in a randomized sequence.\u003c/p\u003e \u003cp\u003e \u003cem\u003eInterstitial needle implantation.\u003c/em\u003e Following general anesthesia, patients underwent vaginal and perineal disinfection, urinary catheter insertion, and interstitial needle implantation. Needle implantation was performed under real-time transabdominal or transrectal ultrasound guidance. For free-handed ISBT, needle implantation was performed without a guidance template; whereas the novel 3D-printed template was utilized for the FAIT-guided ISBT. The number of needles, along with the insertion angles and depths, was predetermined through consensus by three experienced radiation oncologists (Z.J., P.Q., and Y.G.S.), who also performed all implantation procedures. In the treatment of an individual patient, one radiation oncologist performed both the free-handed and FAIT-guided implantations. Following each implantation, necessary adjustments to the needle positions were made based on the review and recommendations of the other two oncologists.\u003c/p\u003e \u003cp\u003e\u003cem\u003eContouring\u003c/em\u003e. After the completion of interstitial needle implantation, patients were allowed to recover from anesthesia before being transferred to computed tomography (CT) simulation. The bladder was filled with 100 mL of normal saline, and CT images were acquired with a slice thickness of 3 mm. Delineation of OARs was performed according to the recommendations of the Groupe Europ\u0026eacute;en de Curieth\u0026eacute;rapie-European Society for Therapeutic Radiology and Oncology (GEC-ESTRO) and International Commission on Radiation Units and Measurement (ICRU) Report 89.[\u003cspan additionalcitationids=\"CR13 CR14\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]The high-risk clinical target volume (HRCTV) was contoured on CT images by integrating findings from clinical examination and pre-BT MRI. The OARs included the bladder, rectum, sigmoid, and bowel. All contouring was performed using the Elekta Oncentra 3D treatment planning system (Elekta AB, Stockholm, Sweden). To minimize inter-observer variability and mitigate potential bias, HRCTV and OARs were initially delineated by a single experienced radiation oncologist (M.J.B., H.D.D., or T.Y.) and subsequently reviewed and modified, if necessary, by the other two radiation oncologists.\u003c/p\u003e \u003cp\u003e\u003cem\u003ePlanning and treatment.\u003c/em\u003e Following contouring, implanted needle reconstruction was performed manually by the brachytherapy dosimetrist (L.R.X. and B.B.). Treatment plans were subsequently optimized using the Inverse Planning Simulated Annealing (IPSA) algorithm, with manual finetuning applied if necessary. All ISBT plans were reviewed and approved by experienced radiation oncologists (M.J.B., H.D.D., and T.Y.). Patients received high-dose-rate (HDR) ISBT by \u003csup\u003e192\u003c/sup\u003eIr source. The prescribed dose per ISBT fraction was HRCTV D\u003csub\u003e90\u003c/sub\u003e 600 cGy. Dose constraints for OARs adhered to GEC-ESTRO recommendations: bladder D\u003csub\u003e2cc\u003c/sub\u003e\u0026thinsp;\u0026lt;\u0026thinsp;8500 cGy; and rectum, sigmoid, and bowel D\u003csub\u003e2cc\u003c/sub\u003e\u0026thinsp;\u0026lt;\u0026thinsp;7500 cGy.[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/p\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003ePatients\u0026rsquo; clinical and pathological characteristics were were incorporated into the data set. Implantation time and dosimetric parameters for each ISBT fraction were recorded. Statistical analyses were performed using SPSS Statistics, Version 23 (IBM Corp., Armonk, NY, USA). Continuous data were presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (SD). Paired Student's \u003cem\u003et\u003c/em\u003e-tests were used to assess differences between groups, with statistical significance defined as \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003ePatient characteristics\u003c/h2\u003e \u003cp\u003eConsecutive patients with LACC treated at Sichuan Cancer Hospital between between February and September 2025 were propectively screened for potential inclusion. Of the 100 patients screened, 55 patients with LACC met eligibility criteria and underwent both free-handed and FAIT-guided ISBT procedures (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The median age of the included patients was 56 years (range, 33\u0026ndash;75). The majority of patients had clinical stage IIB disease (n\u0026thinsp;=\u0026thinsp;34, 61.8%), squamous cell carcinoma (SCC) histology (n\u0026thinsp;=\u0026thinsp;49, 89.1%), and received concurrent chemotherapy (n\u0026thinsp;=\u0026thinsp;51, 92.7%). All patients receiced pelvic EBRT 45\u0026thinsp;~\u0026thinsp;50.4 Gy with conventional fractions, of which 16 (29.1%) received extended-field radiation to para-aortic nodal drainage area and and 25 (45.5%) received lymph node boost to 55\u0026thinsp;~\u0026thinsp;61.6 Gy. The average volume of HRCTV after EBRT was 61.8\u0026thinsp;\u0026plusmn;\u0026thinsp;21.3 cm\u003csup\u003e3\u003c/sup\u003e. (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\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\u003eClinicopathological characteristics of patients with LACC.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCharacteristic\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTotal (n\u0026thinsp;=\u0026thinsp;55) n (%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eAge\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMedian\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e56 \u003cb\u003e(range, 33\u0026ndash;75)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e38 (69.1)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e17 (30.9)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eClinical stage (FIGO 2018)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eⅠ-Ⅱ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e34 (61.8)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eⅢ-Ⅳ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e21 (38.2)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHistology\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSCC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e49 (89.1)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOther\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6 (10.9)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePelvic EBRT dose\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e45\u0026thinsp;~\u0026thinsp;50.4 Gy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30 (54.5)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e45\u0026thinsp;~\u0026thinsp;50.4 Gy with LN boost\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e25 (45.5)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eExtended-filed radiation\u003c/b\u003e\u003c/p\u003e \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\u003e16 (29.1)\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\u003e39 (70.9)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eConcurrent chemotherapy\u003c/b\u003e\u003c/p\u003e \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\u003e51 (92.7)\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\u003e4 (7.3)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHRCTV (cm\u003c/b\u003e\u003csup\u003e\u003cb\u003e3\u003c/b\u003e\u003c/sup\u003e\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAverage\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e61.8\u0026thinsp;\u0026plusmn;\u0026thinsp;21.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFirst ISBT procedure\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFree-handed\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e28 (50.9)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTemplate-guided\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e27 (49.1)\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\n\u003ch3\u003eISBT dosimetric outcomes\u003c/h3\u003e\n\u003cp\u003eThe ISBT procedure was performed without complications such as needle penetration into the bladder or rectum, or implantation-related major vaginal bleeding. There was no significant diffrence on the number of interstitial needles between FAIT-guided and free-handed ISBT (4.88\u0026thinsp;\u0026plusmn;\u0026thinsp;0.90 vs. 4.76\u0026thinsp;\u0026plusmn;\u0026thinsp;1.24; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.30). Implantation time was significantly shortened in FAIT-guided ISBT compared with free-handed ISBT (5.83\u0026thinsp;\u0026plusmn;\u0026thinsp;1.93 vs. 8.03\u0026thinsp;\u0026plusmn;\u0026thinsp;2.71 min; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea\u0026ndash;b).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe volume of HRCTV in FAIT-guided ISBT and free-handed ISBT was 62.48\u0026thinsp;\u0026plusmn;\u0026thinsp;20.92 and 61.20\u0026thinsp;\u0026plusmn;\u0026thinsp;21.81 cm\u003csup\u003e3\u003c/sup\u003e, respectively, with no significant diffrence (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.66) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec). Dose of HRCTV D\u003csub\u003e90\u003c/sub\u003e FAIT-guided ISBT was significantly higher than free-handed ISBT (611.38\u0026thinsp;\u0026plusmn;\u0026thinsp;35.11 vs. 580.86\u0026thinsp;\u0026plusmn;\u0026thinsp;64.65 cGy, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed). As for dosimetric restrictions of OARs (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee and f), D\u003csub\u003e2cc\u003c/sub\u003e and D\u003csub\u003e1cc\u003c/sub\u003e for bladder (D\u003csub\u003e2cc\u003c/sub\u003e 433.38\u0026thinsp;\u0026plusmn;\u0026thinsp;22.84 vs. 435.70\u0026thinsp;\u0026plusmn;\u0026thinsp;28.22 cGy, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.42; D\u003csub\u003e1cc\u003c/sub\u003e 456.27\u0026thinsp;\u0026plusmn;\u0026thinsp;19.03 vs. 463.11\u0026thinsp;\u0026plusmn;\u0026thinsp;24.40 cGy, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.01), rectum (D\u003csub\u003e2cc\u003c/sub\u003e 383.34\u0026thinsp;\u0026plusmn;\u0026thinsp;38.67 vs. 379.13\u0026thinsp;\u0026plusmn;\u0026thinsp;42.17 cGy, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.42; D\u003csub\u003e1cc\u003c/sub\u003e 419.30\u0026thinsp;\u0026plusmn;\u0026thinsp;36.86 vs. 415.76\u0026thinsp;\u0026plusmn;\u0026thinsp;41.59 cGy, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.48 ), sigmoid (D\u003csub\u003e2cc\u003c/sub\u003e 335.79\u0026thinsp;\u0026plusmn;\u0026thinsp;60.54 vs. 325.29\u0026thinsp;\u0026plusmn;\u0026thinsp;84.83 cGy, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.27; D\u003csub\u003e1cc\u003c/sub\u003e 372.34\u0026thinsp;\u0026plusmn;\u0026thinsp;57.06 vs. 362.34\u0026thinsp;\u0026plusmn;\u0026thinsp;88.77 cGy, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.27), and bowel (D\u003csub\u003e2cc\u003c/sub\u003e 324.08\u0026thinsp;\u0026plusmn;\u0026thinsp;68.45 vs. 325.86\u0026thinsp;\u0026plusmn;\u0026thinsp;79.38 cGy, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.85; D\u003csub\u003e1cc\u003c/sub\u003e 357.42\u0026thinsp;\u0026plusmn;\u0026thinsp;65.32 vs. 357.69\u0026thinsp;\u0026plusmn;\u0026thinsp;83.48 cGy, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.98) were very close in FAIT-guided and free-handed ISBTs, with no significant differences for D\u003csub\u003e2cc\u003c/sub\u003e of all OARs (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis single-center, prospective, self-controlled study demonstrated that the novel template FAIT improved target volume dose coverage and shortened needle implantation time in ISBT. It\u0026rsquo;s non‑coplanar, multi‑angle, modular channels design facilitated reproducible placements of lateral and parametrial needles. This capability improved margin coverage in bulky tumors with parametrial infiltration and supported procedural standardization across operators. Furthermore, the application of 3D-printed FAIT enhanced procedural efficiency under general anesthesia and might facilitate the performance of ISBT by less experienced BT oncologists. Given its high practicality and effectiveness in optimizing treatment delivery, the novel template FAIT addressed a critical need. These advantages supported its active promotion for widespread adoption in routine ISBT practice.\u003c/p\u003e \u003cp\u003eOur institute was a high-volume tertiary hospital in western China, and members of the ISBT team were highly experienced in free-handed interstitial implantation. Despite the fact that most patients with LACC in this study had bulky tumors with mean HRCTV volume exceeding 60 cm\u003csup\u003e3\u003c/sup\u003e, nearly optimal HRCTV D\u003csub\u003e90\u003c/sub\u003e dose coverage was consistently achieved using free-handed implantation under real-time transabdominal or transrectal ultrasound guidance. Cumulative radiation dose to HRCTV was strongly associated with local tumor control and overall survival (OS) in LACC. Inadequate dose coverage at the tumor margin, parametrial region, or pelvic sidewall would significantly increase the risk of pelvic recurrence. With the assistance of 3D-printed FAIT, HRCTV dose coverage was further improved without increasing the risk of perforation to pelvic OARs. Moreover, the narrow standard deviation of HRCTV D\u003csub\u003e90\u003c/sub\u003e observed in the FAIT group underscored its superior procedural reproducibility and dosimetric consistency. Importantly, the improved procedural efficiency after the application of FAIT template led to a significant reduction in operation time, thereby alleviating operator\u0026rsquo;s concerns regarding potential injury to the bladder and rectum during needle insertion.\u003c/p\u003e \u003cp\u003eOur findings were consistent with previously reported trends in literatures, supporting the notion that anatomy-driven needle channel planning improved target coverage and OAR sparing[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. The results further underscored the pivotal role of 3D printing in overcoming dosimetric challenges in cases with complex anatomy.[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] Consistent with early reports[\u003cspan additionalcitationids=\"CR20\" citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e], the FAIT approach improved procedural consistency and efficiency through template-guided implantation. Notably, unlike strategies that emphasized either fully customized applicators or pure modular designs[\u003cspan additionalcitationids=\"CR23\" citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e], the structure of FAIT occupied a strategic middle ground by integrating the strengths of both paradigms. It circumvented the need for sophisticated algorithms and specialized infrastructure associated with fully patient-specific solutions, while offering greater flexibility and precision in needle placement through its multi-angle channel configuration. This hybrid design enhanced both clinical accessibility and adaptability in routine ISBT practice.\u003c/p\u003e \u003cp\u003eThis study had several limitations. First, the present study was limited by a short follow-up period, which precluded the evaluation of local tumor control and late radiation-related toxicities. Second, the present workflow mainly relied on manual needle-path planning without the integration of advanced computational tools. Future studies could expand enrollment, prolong follow-up to capture mature clinical outcomes, and investigate the synergistic potential of combining the FAIT template with automated or artificial intelligence-driven needle-path optimization systems to further improve target coverage and enhance OAR sparing.\u003c/p\u003e \u003cp\u003eIn conclusion, the 3D-printed FAIT, which synergistically integrated personalized multi-angle needle guidance with modular standardization to achieve superior dosimetry, enhanced target volume coverage while sparing OARs, and improved procedural efficiency in ISBT for LACC. By bridging the gap between customization and reproducibility, the novel template FAIT held transformative potential to democratize high-quality ISBT.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved by the Ethics Committee for Medical Rescarch and New Medical Technology of Sichuan Cancer Hospital (SCCHEC-02-2025-111), and performed in accordance with the principles of the Declaration of Helsinki. The informed consent form was acquired from each patient prior to BT, and all patient data were de-identified.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no conflicts of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData\u003c/strong\u003e \u003cstrong\u003eavailability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data that support the findings of this study are available from the corresponding author upon reasonable request.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEmployment\u003c/strong\u003e \u003cstrong\u003eor\u003c/strong\u003e \u003cstrong\u003eleadership\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNone declared.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eContributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e(I) Conception and design: L.S., T.Y. and W.X.L. (Ⅱ) Acquisition of data: B.B., T.T., and M.J.B. (Ⅲ) Analysis and interpretation of data: L.R.X., Z.J. and P.Q. (IV)Manuscript writing: L.R.X., Z.J. and P.Q. (V) Revision of the manuscriptdraf: Z.J. H.D.D., Y.G.S. and P.Q. (Ⅵ) Administrative support and study supervision or coordination: all authors. (Ⅶ)Final approval of manuscript: all authors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe authors would like to thank Professor Jingyi Lang and Professor Shichuan Zhang, Department of Radiation Oncology, Precision Radiation in Oncology Key Laboratory of Sichuan Province, Sichuan Clinical Research Center for Cancer, Sichuan Cancer Hospital \u0026amp; Institute, Sichuan Cancer Center, University of Electronic Science and Technology of China, Chengdu, China, for their suggestions in study conception. All FAIT templates were donated by Sichuan Farsoon Turing Additive Manufacturing Co., Ltd. for free use.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by Health Commission of Sichuan Province Medical Science and Technology Program (24LCYJZD07) and Science and Technology Department of Sichuan Province (2026NSFSC1908).\u003c/p\u003e\n"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eSiegel RL, Kratzer TB, Giaquinto AN, Sung H, Jemal A. Cancer statistics, 2025. Ca. 2025;75(1):10. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3322/caac.21871\u003c/span\u003e\u003cspan address=\"10.3322/caac.21871\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWilliamson C, Liu H, Mayadev J, Mell L. 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Radiother Oncol. 2020;148:143\u0026ndash;50. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.radonc.2020.04.017\u003c/span\u003e\u003cspan address=\"10.1016/j.radonc.2020.04.017\" 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":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-cancer","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bcan","sideBox":"Learn more about [BMC Cancer](http://bmccancer.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bcan/default.aspx","title":"BMC Cancer","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Locally advanced cervical cancer, interstitial brachytherapy, guidance template, dosimetry","lastPublishedDoi":"10.21203/rs.3.rs-8657825/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8657825/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eThe application of guidance template in interstitial brachytherapy (ISBT) was expected to improve target coverage and sparing organs at risk for locally advanced cervical cancer (LACC). The purpose of this study was to compare dosimetric and procedural outcomes of template-guided ISBT against free-handed ISBT.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eConsecutive patients with LACC were prospectively enrolled at Sichuan Cancer Hospital from February to September 2025. A novel 3D-printed free-assembled interstitial template (FAIT), featuring a tandem with optimized non-coplanar needle channels, was invented and utilized for ISBT. Each patient underwent both FAIT-guided and free-handed high-dose-rate ISBT within 3 days with a random sequence. Treatment plans were generated in the Oncentra planning system with a 600 cGy prescription, and dosimetric parameters including high-risk clinical target volume (HRCTV) D\u003csub\u003e90\u003c/sub\u003e, dose of organs at risk (OARs) (D\u003csub\u003e1cc\u003c/sub\u003e and D\u003csub\u003e2cc\u003c/sub\u003e for bladder, rectum, sigmoid and bowel) were extracted. The number of interstitial needles and implantation time were also recorded. Data were presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation and compared using paired Student\u0026rsquo;s \u003cem\u003et\u003c/em\u003e-tests. Statistical significance was defined as \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003e55 patients received both FAIT-guided and free-handed ISBT procedures after pelvic external beam radiotherapy (EBRT) of 45-50.4 Gy with 25\u0026ndash;28 fractions. Most patients were stage ⅡB (n\u0026thinsp;=\u0026thinsp;34, 61.8%) and squamous cell carcinoma (n\u0026thinsp;=\u0026thinsp;49, 89.1%), and mean post-EBRT HRCTV volume was 61.8\u0026thinsp;\u0026plusmn;\u0026thinsp;21.3 cm\u003csup\u003e3\u003c/sup\u003e. There was no significant difference on the number of needles used in FAIT-guided and free-handed ISBTs (4.88\u0026thinsp;\u0026plusmn;\u0026thinsp;0.90 vs. 4.76\u0026thinsp;\u0026plusmn;\u0026thinsp;1.24, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.30). FAIT guidance shortened implantation time (5.83\u0026thinsp;\u0026plusmn;\u0026thinsp;1.93 vs 8.03\u0026thinsp;\u0026plusmn;\u0026thinsp;2.71 min, P\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) and achieved higher HRCTV D90 (611.38\u0026thinsp;\u0026plusmn;\u0026thinsp;35.12 vs 580.86\u0026thinsp;\u0026plusmn;\u0026thinsp;64.65 cGy, P\u0026thinsp;\u0026lt;\u0026thinsp;0.01), with similar OAR doses (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eImproved target volume dose coverage and shortened needle implantation time were achieved with the application of the novel 3D-printed FAIT in ISBT. This novel template had high clinical utility and was worthy of further promotion and application.\u003c/p\u003e","manuscriptTitle":"A novel free-assembled template for interstitial brachytherapy of locally advanced cervical cancer: a dosimetric study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-22 12:25:25","doi":"10.21203/rs.3.rs-8657825/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-02-19T06:02:09+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-18T05:10:54+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"301614718927904839602669773150724561878","date":"2026-02-16T04:58:30+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"54648402826187183688409867912528798980","date":"2026-02-13T14:13:40+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-13T13:42:21+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-01-23T09:44:13+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-01-22T09:01:12+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-01-22T08:56:39+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Cancer","date":"2026-01-21T09:10:23+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-cancer","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bcan","sideBox":"Learn more about [BMC Cancer](http://bmccancer.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bcan/default.aspx","title":"BMC Cancer","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"cf337f67-1aaa-41f5-be76-a8285fd1c458","owner":[],"postedDate":"February 22nd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-02-22T12:25:26+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-22 12:25:25","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8657825","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8657825","identity":"rs-8657825","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}