Microdose EOS Imaging: Just as Good, and Safer

Microdose EOS Imaging: Just as Good, and Safer | 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 Microdose EOS Imaging: Just as Good, and Safer Mak Macapagal, Rose Liam, Rachel Williams, Walters Samuel, Gallagher Mathew, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6315925/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Purpose: Children with scoliosis are exposed to significant lifetime radiation doses because of multiple imaging studies as part of their investigation and treatment. EOS scanning has been shown to significantly reduce overall radiation and cancer risk. To reduce radiation further, a microdose setting can be used on the EOS scanner. This study aimed to quantify the reduction in radiation dose and assess image quality compared to the standard EOS settings. Methods: A consecutive group of paediatric patients who received both a standard EOS dose and a microdose EOS scan for investigating their scoliosis within a 6-month period. The radiation doses were compared, and cancer risk was estimated using a validated risk calculator. Assessment of image quality was blindly evaluated by six surgeons, using a five-point visual analogue scale (VAS) between standard and microdose studies. Results: Twenty-five children who received both studies within a six month period were included, median age 13 (IQR 4). The total doses in the standard EOS group were 0.0895 mSv (additional lifetime cancer risk per study: 0.00197%); compared to the microdose group of 0.0167 mSv (additional lifetime cancer risk per study: 0.00037%) (p <.0001). Image quality VAS was not statistically different between settings (standard: 4.2, microdose 4.0) (p = 0.074). Conclusion: Microdose EOS resulted in a five-fold reduction in radiation dose compared to Standard dose EOS and a subsequent 532% decrease in lifetime cancer risk per study. This builds on the fact that Standard dose EOS already carries five times less radiation and cancer risk than plain films. Therefore, compared to traditional radiographs, using a microdose EOS would result in a 40-fold reduction in radiation dose, and a large lifetime reduction in iatrogenic cancer risk. Microdose EOS was found to be both safe and accurate for purpose. A larger study is needed to support these findings. Figures Figure 1 Introduction A fundamental aspect of management for children with Adolescent Idiopathic Scoliosis (AIS) is orthogonal projection radiographs. This enables diagnostic measurements of major coronal curve and the sagittal balance, which are crucial for guiding management with respect to Lenke Classification [ 1 ] Further post-operative and active monitoring radiology is required for appropriate follow-up in these patients, resulting in an average of 16 radiographs required by one patient in their lifetime for their scoliosis alone [ 2 ] Traditionally, radiographs have been the first line modality due to their low cost and accessibility in most hospital settings. However, due to the nature of these scans, children are exposed to large doses of radiation, and with the frequency of imaging required in paediatric scoliosis cases, it is of utmost interest to find alternative, lower risk modalities of imaging to reduce iatrogenic morbidity. A review with a population size of 35,641 has shown that children with scoliosis have significantly elevated rates of cancer and cancer mortality [ 3 ]. It is noteworthy that other studies of registry data have refuted this, however there is caution to be applied to registry data for an exclusively surgical cohort. Nonetheless, reducing the risk of radiation will continue to be a concept which is upheld by the medical community for years to come [ 4 ]. MRI has been considered as an alternative to radiographs for measuring major coronal curves, removing the radiation dose altogether [ 5 , 6 ]. However, this carries many disadvantages from reduced availability of imaging slots, high cost and a prolonged time in the scanner [ 6 ]. MRI scans are also performed supine, which is not suitable for assessing standing deformity, and cannot be utilised to assess curve flexibility in the same way radiographs can [ 7 ]. Furthermore, not all braces are compatible with an MRI scan making this unsuitable for an “in brace” assessment [ 8 ]. Overall, these factors make MRI an inappropriate alternative for investigating our patients. EOS utilises the fundamentals of biplanar radiograph imaging to simultaneously take posteroanterior and lateral images of the whole spine in a single standing position with reduced radiation exposure compared to traditional plain films [ 8 ]. It achieved this by utilising a superior receiver (gas ion chamber) which requires fewer photons to reproduce an image, thereby enabling a lower dose of radiation. This produces a three-dimensional reconstruction of the entire vertebrae using collimated beams and digital image stitching, enabling a greater precision of image due to fewer parabola and repositioning errors [ 9 ]. There is already evidence in place which shows that standard dose EOS imaging can reduce additional lifetime malignancy risk in paediatric scoliosis; showing a 543% reduction compared to plain films [ 10 ]. Notably, EOS also has a microdose protocol which can be used to further reduce the dose of radiation per study at the cost of potentially reducing image quality, without significantly compromising the image quality (Fig. 1 ) [ 11 ]. Our study focused on the microdose protocol, aiming to quantify the reduction in radiation dose compared to the standard dose EOS, whilst subsequently assessing the impact that this has on image quality to reduce iatrogenic radiation exposure even further without compromising quality. We hypothesise that EOS microdose will be adequate for routine monitoring and clinical decision-making purposes, and the resultant lower dose in radiation required will have a profound effect on reducing cancer risk compared to traditional radiographs. Methods Both standard dose and microdose EOS studies were used as per regular practice. This practice includes a standard dose EOS at first presentation, and the microdose for follow-up images, such as for brace fitting, and curve monitoring. Each patient will have variable EOS scan frequencies depending on their clinical needs. All consecutive paediatric patients (under 18 years old) who had received both a standard dose EOS scan and a Microdose EOS scan for investigating their scoliosis within a six-month period, for any reason were reviewed. The rationale was minimising the time elapsed between studies avoiding large differences in patient size, and hence radiation dose. No additional scans were requested for the purpose of this study. All data were obtained from a tertiary spinal centre in the UK, and we have sought ethical approval via our clinical governance pathway to retrospectively review this data for research purposes. The total radiation dose was obtained in dose area product (DAP) (mGy.cm2) for each patient by combining both Antero-Posterior (AP) and lateral doses. A conversion coefficient was used to calculate the estimated total radiation dose in Millisieverts (mSv) from DAP. The “Thoracic PA” and “Thoracic Lateral” coefficients were used as it is the closest reflection of whole spine imaging [ 12 ]. The total radiation doses were compared, and additional lifetime cancer risk was estimated using a validated risk of cancer tool; to estimate additional mean risk per effective dose of radiation [ 14 ]. The “upper back x-ray” setting was used, which may underestimate the actual radiation risk this the closest option to a whole spine study. Overall, the difference in additional lifetime cancer risk between EOS standard- dose and microdose was calculated. The paired t- test was used to compare the mean values of the radiation doses applied to the same individual. Significance was set at p < 0.05 [ 9 ]. In order to assess image quality for purpose of major coronal curve measurements six spine surgeons (Consultants and Fellows) blindly rated and compared image exposure quality, using a five-point visual analogue scale (VAS) (Table 1 ) between standard and microdose studies of 20 images (10 regular dose and 10 microdose). The mean value of the VAS scores for standard and microdose were compared, using the paired t test. Significance was set at p < 0.05. [insert Table 1 ] Table 1 Visual Analogue Score (VAS) for EOS Image quality Score Descriptor 1 Very Poor - Unable to identify key structures 2 Unsatisfactory - Repeat imaging required 3 Satisfactory - Clinically acceptable, but grainy 4 Good - Anatomy well-defined 5 Excellent - Flawless definition of anatomy Results Twenty five children met the inclusion criteria (19:6, female:male) with a median age 13 (IQR 4). In the standard EOS dose group, after converting from DAP to mSv, the mean PA dose was 0.0626 mSv (range .0303 − .0840) and mean lateral dose of 0.0269 mSv (range .0136 − .0337) . In the Microdose EOS group the mean lateral dose was 0.00659 mSv (range .00253 − .0101) and PA dose of 0.0101 mSv (range .00414 − .0153), resulting in a total dose of 0.0167 mSv (range .00667 − .0244). [insert Table 2 ] Table 2 Estimated mean radiation doses (mSv) for lateral, PA and total dose for Standard and Microdose EOS, with differences (%). Lateral PA Total Dose Standard EOS 0.0269 mSv (.0136 − .0337) 0.0626 mSv (.0303 − .0840) 0.0895 mSv (.0440 − .1177) Microdose EOS 0.00659 mSv (.00253 − .00101) 0.0101 mSv (.00414 − .0153) 0.0167 mSv (.00667 − .0244) % difference 408.2 619.8 535.9 When calculating additional cancer risk for each individual patient. The standard EOS dose resulted in an additional mean cancer risk of 0.00115% for male patients (range .0077 − .00156) and an additional mean cancer risk of 0.00222% for female patients (range .00138 − .00271). Combined additional cancer risk with Standard EOS dose was 0.00197% per study. With microdose, the additional calculated mean cancer risk for male patients was 0.00021% (range .00012 − .00029) and 0.00041% for female patients (range .00026 − .00056). Combined calculated additional cancer risk with microdose was 0.00037% per study. This is in addition to the baseline lifetime cancer risk of 44.9% in males and 37.5% in females. The combined additional cancer risk reduction was found to be a 532% per study using microdose compared to Standard EOS dose. A statistically significant difference was found between additional cancer risk per study in standard EOS (Mean = 1.97%, SD = 0.606) and Microdose (Mean = 0.372%, SD = 0.129) (p < .0001). [insert Table 3] Table 3 Additional male, female and combined lifetime cancer risk per study based on total radiation dose for regular dose and microdose EOS. Total Dose (mSv) Male Additional Cancer Risk (%) Female Additional Cancer Risk (%) Combined Additional Cancer Risk (%) Regular Dose EOS .0895 .00115% .00222% .00197% Microdose EOS .0167 .00021% .00041% .00037% The VAS scoring for image quality results found Standard EOS had a mean rating of 4.2 (2–5) and microdose had an average rating of 4.0 (2–5). This was not statistically significant ( p = .074). Both image modalities were categorised as “4 - Good - Anatomy well-defined”. [insert Table 4 ] Table 4 Mean Visual Analogue Scale (VAS) Score compared between Regular Dose and Microdose. Based on a blinded comparison of 6 surgeons. Regular Dose (Range) Microdose (Range) p value Mean VAS score 4.2 (2–5) 4.0 (2–5) 0.074 Discussion This study found that in this population of children with AIS, the microdose setting on EOS resulted in a fivefold reduction in radiation dose and additional lifetime cancer risk per study when compared to the standard EOS dose, without compromising image quality. Plain films have been found to have a mean estimated effective dose of 0.68mSv per spine study [ 10 ]. Comparatively, a microdose EOS (0.0167mSv) has a 40-fold reduction in radiation dose per study [ 10 ]. On average, a patient with AIS will undergo 16 radiograph studies in their lifetime [ 2 ]. Using our data, a patient receiving this number of images with standard EOS dose would receive 1.43mSv of additional radiation as a result of their condition. In comparison, using a microdose for the same number of studies would result in an additional 0.27mSv, thereby making the radiation dose near negligible. Assuming daily background dose to be 0.0066mSv, a standard EOS dose equates to 216 days whereas microdose would only be 41 days; resulting in 175 fewer days of background radiation in a lifetime [ 14 ]. Although radiation dose and cancer risk may not have a linear correlation, it is a useful surrogate. One study showed a fivefold increase in overall cancer incidence for patients with AIS compared to an aged-matched population. The AIS patients were exposed to an average of 16 lifetime studies, with an average mean radiation of 0.8–1.4mSv [ 15 ]. A review of radiation exposure in scoliosis patients showed that in a population of 35,641 patients, the incidence rates of cancer, breast cancer and cancer mortality was significantly higher in the scoliosis patient group compared to the controls. It is therefore reasonable to assume that reducing the total radiation exposure for patients would provide a potential health benefits, especially in terms of reducing cancer incidence [ 4 , 15 ]. Current NICE guidelines about EOS state that “Current evidence shows there are some patient benefits for people with spinal deformities in terms of radiation dose reduction and increased throughput. However, those benefits alone are insufficient to justify the cost of the system”. They do however acknowledge that EOS could be an “important emerging technology” but that there needed to be more evidence to quantify the benefits of the system. This study adds further evidence regarding the diagnostic strength of the EOS system, showing the significant impact this would have on reducing radiation exposure in a paediatric patient cohort [ 16 ]. According to the Royal College of Radiologists, in the Ionising Radiation (Medical Exposure) Regulations (IR(ME)R), clinicians should “Ensure Exposures are kept as low as reasonably practicable” when treating patients. Therefore, using the microdose setting in EOS as an equivalent but lower dose investigation should be of utmost priority, owing to the lawful and ethical duty to patients [ 17 ]. This study has limitations in estimating radiation dose and additional cancer risk. When converting DAP to mSv, a “Thoracic PA “ and “Thoracic Lateral” settings was used on the calculator as there is no acknowledged conversion coefficient for the whole spine. Furthermore, in calculating the plain radiograph risk from effective dose in mSv, the “Upper Back X-ray” setting was used as there was no whole spine option. It was estimated that both of these factors may result in an underestimation of additional cancer risk in this study. It is recognised that this study was performed by surgeons for the purpose of surgical evaluation of the major coronal curve in EOS images, rather than by radiologists for diagnostic purposes. Our unit still performs a Standard EOS dose as the very first study instead of radiographs and utilises microdose EOS for subsequent follow-up studies. EOS microdose is now our standard tool for following up outpatients, and the authors now feel more relaxed about radiation in this setting without compromising image quality – in fact, we feel the EOS has many technical advantages. This study’s results are comparable with other studies investigating microdose versus standard EOS dose, showing a five to six times reduction (albeit on Anthropomorphic Phantoms) respectively [ 11 , 18 ] Although there is already evidence showing satisfactory images when utilising microdose EOS, as far as we are aware, our study in the only comparative study which both quantifies the difference in radiation dose between standard EOS dose and microdose, while comparing the image quality between the scans. The VAS score is indeed not validated for this purpose; however, the method was used for assessing EOS image quality, not the accuracy of the deformity measurements. The VAS results did categorise standard EOS dose and microdose as “4 - Good - Anatomy well-defined” without statistical significance, this seems to be adequate to conclude there is non-inferiority with regards to the relevant clinical significance. Conclusion Microdose EOS resulted in a five-fold reduction in radiation dose compared to Standard EOS and resulted in a 532% decrease in lifetime calculated cancer risk per study. Compared to traditional radiographs, the microdose setting would result in a 40-fold reduction in radiation dose per study. Image quality with microdose is also non-inferior for purpose compared to standard EOS settings when subject to blinded comparison. Further research is needed before this could be recommended as regular practice. This study contributes to the body of evidence aiming to review the NICE guidelines for EOS guidelines. EOS microdose settings appear to be both safe and accurate, although a larger comparative study should be conducted to confirm these findings before we can recommend using these settings routinely. Declarations Ethics approval and consent to participate Ethical approval was not required for this retrospective study, which used anonymised patient radiographs only. The study was registered with The St George’s Hospital Clinical Governance Department, and in accordance with our local policies, informed consent form parents/guardians was not required, and was waived. The study was conducted in accordance with the principles of the Declaration of Helsinki. Consent for publication Consent for publication by participants was not required, in accordance with the above. However we do have permission to publish using data acquired from our Trust. Availability of data and materials From corresponding author upon request Competing Interests None declared. Funding Not applicable Authors' contributions All authors contributed to data collection and review. Authors MM and LR were responsible for study design and drafting of the manuscript. Acknowledgements Not applicable. References Lenke LG et al. (2001) Adolescent idiopathic scoliosis: a new classification to determine extent of spinal arthrodesis. J Bone Joint Surg Am 83:1169–1181 Lenke LG, Edwards CC, Bridwell KH (2003) The Lenke classification of adolescent idiopathic scoliosis: how it organizes curve patterns as a template to perform selective fusions of the spine. Spine 28.: https://doi.org/10.1097/01.BRS.0000092216.16155.33 Ng S-Y, Bettany-Saltikov J (2017) Suppl-9, M5: Imaging in the Diagnosis and Monitoring of Children with Idiopathic Scoliosis. Open Orthop J 11:1500. https://doi.org/10.2174/1874325001711011500 Cundy PJ, Venugopal K, Antoniou G, Brooks F, Freeman BJC, D’Onise K (2020) Do Children With Spinal Deformity Who Have Metal Implants and Frequent Exposure to X-Rays Increase Their Risk of Cancer? Spine 45:1200–1207. https://doi.org/10.1097/BRS.0000000000003507 Maizlin ZV, Vos PM (2012) How to measure scapholunate and Cobb’s angles on MRI and CT. J Digit Imaging 25:558–561. https://doi.org/10.1007/s10278-011-9438-2 Johnson MA, Gohel S, Mitchell SL, Flynn JJM, Baldwin KD (2021) Entire-spine Magnetic Resonance Imaging Findings and Costs in Children With Presumed Adolescent Idiopathic Scoliosis. J Pediatr Orthop 41:585–590. https://doi.org/10.1097/BPO.0000000000001943 Kaiser R, Behrbalk E, Walsh M, Waldauf P, Perez Romera AB, Mehdian H (2017) Can MRI Predict Flexibility in Scheuermann Kyphosis Patients? Clin Spine Surg 30:E938–E941. https://doi.org/10.1097/BSD.0000000000000346 EOS is a low-dose radiation alternative to X-rays and CT. In: Hospital for Special Surgery. https://www.hss.edu/condition-list_eos-imaging.asp. Accessed 5 Jun 2024 Wade R, Yang H, McKenna C, Faria R, Gummerson N, Woolacott N (2012) A systematic review of the clinical effectiveness of EOS 2D/3D X-ray imaging system. Eur Spine J 22:296–304. https://doi.org/10.1007/s00586-012-2469-7 Rose LD, Williams R, Ajayi B, Abdalla M, Bernard J, Bishop T, Papadakos N, Lui DF (2023) Reducing radiation exposure and cancer risk for children with scoliosis: EOS the new gold standard. Spine Deformity 11:847. https://doi.org/10.1007/s43390-023-00653-6 Ilharreborde B, Ferrero E, Alison M, Mazda K (2016) EOS microdose protocol for the radiological follow-up of adolescent idiopathic scoliosis. Eur Spine J 25.: https://doi.org/10.1007/s00586-015-3960-8 August DAP to mSv converter - radiography. https://www.dosewizard.com/2019/08/effective-dose-calculator-radiography.html. Accessed 28 Feb 2024 X-Ray Risk Calculator. Available at: https://www.xrayrisk.com. Accessed 28 Feb 2024. Thorne MC (2003) Background radiation: natural and man-made. J Radiol Prot 23.: https://doi.org/10.1088/0952-4746/23/1/302 Simony A, Hansen EJ, Christensen SB, Carreon LY, Andersen MO (2016) Incidence of cancer in adolescent idiopathic scoliosis patients treated 25 years previously. Eur Spine J 25:3366–3370. https://doi.org/10.1007/s00586-016-4747-2 Recommendations | The EOS 2D/3D imaging system | Guidance | NICE. Available at: https://www.nice.org.uk/guidance/dg1. Accessed 28 Feb 2024. IR(ME)R: Implications for clinical practice in diagnostic imaging, interventional radiology and diagnostic nuclear medicine. https://www.rcr.ac.uk/our-services/all-our-publications/clinical-radiology-publications/ir-me-r-implications-for-clinical-practice-in-diagnostic-imaging-interventional-radiology-and-diagnostic-nuclear-medicine/. Accessed 28 Feb 2024 Pedersen PH, Petersen AG, Østgaard SE, Tvedebrink T, Eiskjær SP (2018) EOS Micro-dose Protocol: First Full-spine Radiation Dose Measurements in Anthropomorphic Phantoms and Comparisons with EOS Standard-dose and Conventional Digital Radiology. Spine 43.: https://doi.org/10.1097/BRS.0000000000002696 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted 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-6315925","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":457544646,"identity":"c0706a96-579a-4d55-a42b-fc95044c7caf","order_by":0,"name":"Mak Macapagal","email":"","orcid":"","institution":"St. George’s University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Mak","middleName":"","lastName":"Macapagal","suffix":""},{"id":457544647,"identity":"e18e1dae-ff9b-4d35-a242-ae3f0d52932e","order_by":1,"name":"Rose Liam","email":"","orcid":"","institution":"St. George’s University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Rose","middleName":"","lastName":"Liam","suffix":""},{"id":457544649,"identity":"d253d166-97ab-4b79-a65e-923a6e1a13e5","order_by":2,"name":"Rachel Williams","email":"","orcid":"","institution":"St. George’s University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Rachel","middleName":"","lastName":"Williams","suffix":""},{"id":457544651,"identity":"ad7e9b2b-9cea-43ff-9565-a3668903bc37","order_by":3,"name":"Walters Samuel","email":"","orcid":"","institution":"St. George’s University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Walters","middleName":"","lastName":"Samuel","suffix":""},{"id":457544652,"identity":"a5025583-8631-4226-8306-d0068394ad6e","order_by":4,"name":"Gallagher Mathew","email":"","orcid":"","institution":"St. George’s University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Gallagher","middleName":"","lastName":"Mathew","suffix":""},{"id":457544654,"identity":"fef1b678-5012-4b38-b09f-77853d2c1f7b","order_by":5,"name":"Raza Hasan","email":"","orcid":"","institution":"St. George’s University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Raza","middleName":"","lastName":"Hasan","suffix":""},{"id":457544655,"identity":"7e776e26-5b10-443a-866e-72ee232b442c","order_by":6,"name":"Bishop Tim","email":"","orcid":"","institution":"St. George’s University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Bishop","middleName":"","lastName":"Tim","suffix":""},{"id":457544656,"identity":"c814103e-9e7b-4e69-8bd9-6f81947d9094","order_by":7,"name":"Gelfer Yael","email":"","orcid":"","institution":"St. George’s University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Gelfer","middleName":"","lastName":"Yael","suffix":""},{"id":457544657,"identity":"0bc9f932-7e79-4cc2-97e7-87d0c38ab0f7","order_by":8,"name":"Bernard Jason","email":"","orcid":"","institution":"St. George’s University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Bernard","middleName":"","lastName":"Jason","suffix":""},{"id":457544658,"identity":"97731731-a6aa-44e2-80c9-9812378c2650","order_by":9,"name":"Lui Darren","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA2ElEQVRIie3PMQuCQBTA8ZMH5/KyVUH8DAdCBH2ZpmvRbxCNbrX7LZqiUTjSxXB1FxyaDCEIKrqzpclsC7r/cLzhfrw7QnS6XyzpTs8lAGq03aHERwJ0rgh+QQgyNX0mVnasm/OeIcuwPZXLKRJTHLZ9xMkXfhznkojRbhak8mHIedlHWMIBRtGtI35AJbFx0k+KGuAeqS1Y+8FjCCnlFuNFoAqjAcQpazDWkjiCTiDc2Eg//cUqOJBrxDyrEFUbXFbe2BRpL3mP2t059LoKmm9u63Q63f/0BHQ4QkoaP1R6AAAAAElFTkSuQmCC","orcid":"","institution":"St. George’s University Hospital","correspondingAuthor":true,"prefix":"","firstName":"Lui","middleName":"","lastName":"Darren","suffix":""}],"badges":[],"createdAt":"2025-03-27 01:23:17","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6315925/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6315925/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":83126789,"identity":"1c4b82ae-8ff0-4f8e-a199-49ff7248c52d","added_by":"auto","created_at":"2025-05-20 09:48:53","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":345229,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eA qualitative image comparison of an AP whole spine regular dose Scan (Left) compared to an AP whole spin microdose Scan (Right). The same patient at different points in time.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6315925/v1/cec8cf154ff123c024dd1f4b.jpeg"},{"id":107518210,"identity":"0c3424e4-675b-4754-9c74-416a6ec0f2ed","added_by":"auto","created_at":"2026-04-22 08:43:45","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":698514,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6315925/v1/d563ea7b-578b-47d2-b299-7f7eeddf25cb.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Microdose EOS Imaging: Just as Good, and Safer","fulltext":[{"header":"Introduction","content":"\u003cp\u003eA fundamental aspect of management for children with Adolescent Idiopathic Scoliosis (AIS) is orthogonal projection radiographs. This enables diagnostic measurements of major coronal curve and the sagittal balance, which are crucial for guiding management with respect to Lenke Classification [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] Further post-operative and active monitoring radiology is required for appropriate follow-up in these patients, resulting in an average of 16 radiographs required by one patient in their lifetime for their scoliosis alone [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eTraditionally, radiographs have been the first line modality due to their low cost and accessibility in most hospital settings. However, due to the nature of these scans, children are exposed to large doses of radiation, and with the frequency of imaging required in paediatric scoliosis cases, it is of utmost interest to find alternative, lower risk modalities of imaging to reduce iatrogenic morbidity. A review with a population size of 35,641 has shown that children with scoliosis have significantly elevated rates of cancer and cancer mortality [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. It is noteworthy that other studies of registry data have refuted this, however there is caution to be applied to registry data for an exclusively surgical cohort. Nonetheless, reducing the risk of radiation will continue to be a concept which is upheld by the medical community for years to come [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eMRI has been considered as an alternative to radiographs for measuring major coronal curves, removing the radiation dose altogether [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. However, this carries many disadvantages from reduced availability of imaging slots, high cost and a prolonged time in the scanner [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. MRI scans are also performed supine, which is not suitable for assessing standing deformity, and cannot be utilised to assess curve flexibility in the same way radiographs can [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Furthermore, not all braces are compatible with an MRI scan making this unsuitable for an \u0026ldquo;in brace\u0026rdquo; assessment [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Overall, these factors make MRI an inappropriate alternative for investigating our patients.\u003c/p\u003e \u003cp\u003eEOS utilises the fundamentals of biplanar radiograph imaging to simultaneously take posteroanterior and lateral images of the whole spine in a single standing position with reduced radiation exposure compared to traditional plain films [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. It achieved this by utilising a superior receiver (gas ion chamber) which requires fewer photons to reproduce an image, thereby enabling a lower dose of radiation. This produces a three-dimensional reconstruction of the entire vertebrae using collimated beams and digital image stitching, enabling a greater precision of image due to fewer parabola and repositioning errors [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThere is already evidence in place which shows that standard dose EOS imaging can reduce additional lifetime malignancy risk in paediatric scoliosis; showing a 543% reduction compared to plain films [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Notably, EOS also has a microdose protocol which can be used to further reduce the dose of radiation per study at the cost of potentially reducing image quality, without significantly compromising the image quality (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Our study focused on the microdose protocol, aiming to quantify the reduction in radiation dose compared to the standard dose EOS, whilst subsequently assessing the impact that this has on image quality to reduce iatrogenic radiation exposure even further without compromising quality.\u003c/p\u003e \u003cp\u003eWe hypothesise that EOS microdose will be adequate for routine monitoring and clinical decision-making purposes, and the resultant lower dose in radiation required will have a profound effect on reducing cancer risk compared to traditional radiographs.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eBoth standard dose and microdose EOS studies were used as per regular practice. This practice includes a standard dose EOS at first presentation, and the microdose for follow-up images, such as for brace fitting, and curve monitoring. Each patient will have variable EOS scan frequencies depending on their clinical needs. All consecutive paediatric patients (under 18 years old) who had received both a standard dose EOS scan and a Microdose EOS scan for investigating their scoliosis within a six-month period, for any reason were reviewed. The rationale was minimising the time elapsed between studies avoiding large differences in patient size, and hence radiation dose. No additional scans were requested for the purpose of this study. All data were obtained from a tertiary spinal centre in the UK, and we have sought ethical approval via our clinical governance pathway to retrospectively review this data for research purposes.\u003c/p\u003e \u003cp\u003eThe total radiation dose was obtained in dose area product (DAP) (mGy.cm2) for each patient by combining both Antero-Posterior (AP) and lateral doses. A conversion coefficient was used to calculate the estimated total radiation dose in Millisieverts (mSv) from DAP. The \u0026ldquo;Thoracic PA\u0026rdquo; and \u0026ldquo;Thoracic Lateral\u0026rdquo; coefficients were used as it is the closest reflection of whole spine imaging [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe total radiation doses were compared, and additional lifetime cancer risk was estimated using a validated risk of cancer tool; to estimate additional mean risk per effective dose of radiation [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. The \u0026ldquo;upper back x-ray\u0026rdquo; setting was used, which may underestimate the actual radiation risk this the closest option to a whole spine study. Overall, the difference in additional lifetime cancer risk between EOS standard- dose and microdose was calculated. The paired t- test was used to compare the mean values of the radiation doses applied to the same individual. Significance was set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn order to assess image quality for purpose of major coronal curve measurements six spine surgeons (Consultants and Fellows) blindly rated and compared image exposure quality, using a five-point visual analogue scale (VAS) (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) between standard and microdose studies of 20 images (10 regular dose and 10 microdose). The mean value of the VAS scores for standard and microdose were compared, using the paired t test. Significance was set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003cp\u003e[insert Table \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\u003eVisual Analogue Score (VAS) for EOS Image quality\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\u003eScore\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDescriptor\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eVery Poor - Unable to identify key structures\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eUnsatisfactory - Repeat imaging required\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSatisfactory - Clinically acceptable, but grainy\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGood - Anatomy well-defined\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eExcellent - Flawless definition of anatomy\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eTwenty five children met the inclusion criteria (19:6, female:male) with a median age 13 (IQR 4).\u003c/p\u003e\n\u003cp\u003eIn the standard EOS dose group, after converting from DAP to mSv, the mean PA dose was 0.0626 mSv (range .0303 \u0026minus;\u0026thinsp;.0840) and mean lateral dose of 0.0269 mSv (range .0136 \u0026minus;\u0026thinsp;.0337) .\u003c/p\u003e\n\u003cp\u003eIn the Microdose EOS group the mean lateral dose was 0.00659 mSv (range .00253 \u0026minus;\u0026thinsp;.0101) and PA dose of 0.0101 mSv (range .00414 \u0026minus;\u0026thinsp;.0153), resulting in a total dose of 0.0167 mSv (range .00667 \u0026minus;\u0026thinsp;.0244).\u003c/p\u003e\n\u003cp\u003e[insert Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e]\u003c/p\u003e\n\u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eEstimated mean radiation doses (mSv) for lateral, PA and total dose for Standard and Microdose EOS, with differences (%).\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eLateral\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePA\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTotal Dose\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eStandard EOS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.0269 mSv\u003c/p\u003e\n \u003cp\u003e(.0136 \u0026minus;\u0026thinsp;.0337)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.0626 mSv\u003c/p\u003e\n \u003cp\u003e(.0303 \u0026minus;\u0026thinsp;.0840)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.0895 mSv\u003c/p\u003e\n \u003cp\u003e(.0440 \u0026minus;\u0026thinsp;.1177)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMicrodose EOS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.00659 mSv\u003c/p\u003e\n \u003cp\u003e(.00253 \u0026minus;\u0026thinsp;.00101)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.0101 mSv\u003c/p\u003e\n \u003cp\u003e(.00414 \u0026minus;\u0026thinsp;.0153)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.0167 mSv\u003c/p\u003e\n \u003cp\u003e(.00667 \u0026minus;\u0026thinsp;.0244)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e% difference\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e408.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e619.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e535.9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eWhen calculating additional cancer risk for each individual patient. The standard EOS dose resulted in an additional mean cancer risk of 0.00115% for male patients (range .0077 \u0026minus;\u0026thinsp;.00156) and an additional mean cancer risk of 0.00222% for female patients (range .00138 \u0026minus;\u0026thinsp;.00271). Combined additional cancer risk with Standard EOS dose was 0.00197% per study.\u003c/p\u003e\n\u003cp\u003eWith microdose, the additional calculated mean cancer risk for male patients was 0.00021% (range .00012 \u0026minus;\u0026thinsp;.00029) and 0.00041% for female patients (range .00026 \u0026minus;\u0026thinsp;.00056). Combined calculated additional cancer risk with microdose was 0.00037% per study. This is in addition to the baseline lifetime cancer risk of 44.9% in males and 37.5% in females.\u003c/p\u003e\n\u003cp\u003eThe combined additional cancer risk reduction was found to be a 532% per study using microdose compared to Standard EOS dose. A statistically significant difference was found between additional cancer risk per study in standard EOS (Mean\u0026thinsp;=\u0026thinsp;1.97%, SD\u0026thinsp;=\u0026thinsp;0.606) and Microdose (Mean\u0026thinsp;=\u0026thinsp;0.372%, SD\u0026thinsp;=\u0026thinsp;0.129) (p\u0026thinsp;\u0026lt;\u0026thinsp;.0001).\u003c/p\u003e\n\u003cp\u003e[insert Table 3]\u003c/p\u003e\n\u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eAdditional male, female and combined lifetime cancer risk per study based on total radiation dose for regular dose and microdose EOS.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTotal Dose (mSv)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMale Additional Cancer Risk (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFemale Additional Cancer Risk (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eCombined Additional Cancer Risk (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRegular Dose\u003c/p\u003e\n \u003cp\u003eEOS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e.0895\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e.00115%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e.00222%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e.00197%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMicrodose\u003c/p\u003e\n \u003cp\u003eEOS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e.0167\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e.00021%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e.00041%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e.00037%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eThe VAS scoring for image quality results found Standard EOS had a mean rating of 4.2 (2\u0026ndash;5) and microdose had an average rating of 4.0 (2\u0026ndash;5). This was not statistically significant (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.074). Both image modalities were categorised as \u0026ldquo;4 - Good - Anatomy well-defined\u0026rdquo;.\u003c/p\u003e\n\u003cp\u003e[insert Table \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e]\u003c/p\u003e\n\u003ctable id=\"Tab4\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eMean Visual Analogue Scale (VAS) Score compared between Regular Dose and Microdose. Based on a blinded comparison of 6 surgeons.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eRegular Dose (Range)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMicrodose (Range)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ep\u003c/em\u003e value\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMean VAS score\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.2 (2\u0026ndash;5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.0 (2\u0026ndash;5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.074\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study found that in this population of children with AIS, the microdose setting on EOS resulted in a fivefold reduction in radiation dose and additional lifetime cancer risk per study when compared to the standard EOS dose, without compromising image quality.\u003c/p\u003e \u003cp\u003ePlain films have been found to have a mean estimated effective dose of 0.68mSv per spine study [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Comparatively, a microdose EOS (0.0167mSv) has a 40-fold reduction in radiation dose per study [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eOn average, a patient with AIS will undergo 16 radiograph studies in their lifetime [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Using our data, a patient receiving this number of images with standard EOS dose would receive 1.43mSv of additional radiation as a result of their condition. In comparison, using a microdose for the same number of studies would result in an additional 0.27mSv, thereby making the radiation dose near negligible.\u003c/p\u003e \u003cp\u003eAssuming daily background dose to be 0.0066mSv, a standard EOS dose equates to 216 days whereas microdose would only be 41 days; resulting in 175 fewer days of background radiation in a lifetime [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAlthough radiation dose and cancer risk may not have a linear correlation, it is a useful surrogate. One study showed a fivefold increase in overall cancer incidence for patients with AIS compared to an aged-matched population. The AIS patients were exposed to an average of 16 lifetime studies, with an average mean radiation of 0.8\u0026ndash;1.4mSv [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eA review of radiation exposure in scoliosis patients showed that in a population of 35,641 patients, the incidence rates of cancer, breast cancer and cancer mortality was significantly higher in the scoliosis patient group compared to the controls. It is therefore reasonable to assume that reducing the total radiation exposure for patients would provide a potential health benefits, especially in terms of reducing cancer incidence [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e Current NICE guidelines about EOS state that \u0026ldquo;Current evidence shows there are some patient benefits for people with spinal deformities in terms of radiation dose reduction and increased throughput. However, those benefits alone are insufficient to justify the cost of the system\u0026rdquo;. They do however acknowledge that EOS could be an \u0026ldquo;important emerging technology\u0026rdquo; but that there needed to be more evidence to quantify the benefits of the system. This study adds further evidence regarding the diagnostic strength of the EOS system, showing the significant impact this would have on reducing radiation exposure in a paediatric patient cohort [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAccording to the Royal College of Radiologists, in the Ionising Radiation (Medical Exposure) Regulations (IR(ME)R), clinicians should \u0026ldquo;Ensure Exposures are kept as low as reasonably practicable\u0026rdquo; when treating patients. Therefore, using the microdose setting in EOS as an equivalent but lower dose investigation should be of utmost priority, owing to the lawful and ethical duty to patients [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThis study has limitations in estimating radiation dose and additional cancer risk. When converting DAP to mSv, a \u0026ldquo;Thoracic PA \u0026ldquo; and \u0026ldquo;Thoracic Lateral\u0026rdquo; settings was used on the calculator as there is no acknowledged conversion coefficient for the whole spine. Furthermore, in calculating the plain radiograph risk from effective dose in mSv, the \u0026ldquo;Upper Back X-ray\u0026rdquo; setting was used as there was no whole spine option. It was estimated that both of these factors may result in an underestimation of additional cancer risk in this study.\u003c/p\u003e \u003cp\u003eIt is recognised that this study was performed by surgeons for the purpose of surgical evaluation of the major coronal curve in EOS images, rather than by radiologists for diagnostic purposes. Our unit still performs a Standard EOS dose as the very first study instead of radiographs and utilises microdose EOS for subsequent follow-up studies. EOS microdose is now our standard tool for following up outpatients, and the authors now feel more relaxed about radiation in this setting without compromising image quality \u0026ndash; in fact, we feel the EOS has many technical advantages.\u003c/p\u003e \u003cp\u003eThis study\u0026rsquo;s results are comparable with other studies investigating microdose versus standard EOS dose, showing a five to six times reduction (albeit on Anthropomorphic Phantoms) respectively [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eAlthough there is already evidence showing satisfactory images when utilising microdose EOS, as far as we are aware, our study in the only comparative study which both quantifies the difference in radiation dose between standard EOS dose and microdose, while comparing the image quality between the scans. The VAS score is indeed not validated for this purpose; however, the method was used for assessing EOS image quality, not the accuracy of the deformity measurements. The VAS results did categorise standard EOS dose and microdose as \u0026ldquo;4 - Good - Anatomy well-defined\u0026rdquo; without statistical significance, this seems to be adequate to conclude there is non-inferiority with regards to the relevant clinical significance.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eMicrodose EOS resulted in a five-fold reduction in radiation dose compared to Standard EOS and resulted in a 532% decrease in lifetime calculated cancer risk per study. Compared to traditional radiographs, the microdose setting would result in a 40-fold reduction in radiation dose per study. Image quality with microdose is also non-inferior for purpose compared to standard EOS settings when subject to blinded comparison.\u003c/p\u003e \u003cp\u003eFurther research is needed before this could be recommended as regular practice. This study contributes to the body of evidence aiming to review the NICE guidelines for EOS guidelines.\u003c/p\u003e \u003cp\u003eEOS microdose settings appear to be both safe and accurate, although a larger comparative study should be conducted to confirm these findings before we can recommend using these settings routinely.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEthical approval was not required for this retrospective study, which used anonymised patient radiographs only. The study was registered with The St George\u0026rsquo;s Hospital Clinical Governance Department, and in accordance with our local policies, informed consent form parents/guardians was not required, and was waived. The study was conducted in accordance with the principles of the Declaration of Helsinki.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConsent for publication by participants was not required, in accordance with the above. However we do have permission to publish using data acquired from our Trust.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFrom corresponding author upon request\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNone declared.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors contributed to data collection and review. Authors MM and LR were responsible for study design and drafting of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eLenke LG et al. (2001) Adolescent idiopathic scoliosis: a new classification to determine extent of spinal arthrodesis. J Bone Joint Surg Am 83:1169\u0026ndash;1181\u003c/li\u003e\n\u003cli\u003eLenke LG, Edwards CC, Bridwell KH (2003) The Lenke classification of adolescent idiopathic scoliosis: how it organizes curve patterns as a template to perform selective fusions of the spine. Spine 28.: https://doi.org/10.1097/01.BRS.0000092216.16155.33\u003c/li\u003e\n\u003cli\u003eNg S-Y, Bettany-Saltikov J (2017) Suppl-9, M5: Imaging in the Diagnosis and Monitoring of Children with Idiopathic Scoliosis. Open Orthop J 11:1500. https://doi.org/10.2174/1874325001711011500\u003c/li\u003e\n\u003cli\u003eCundy PJ, Venugopal K, Antoniou G, Brooks F, Freeman BJC, D\u0026rsquo;Onise K (2020) Do Children With Spinal Deformity Who Have Metal Implants and Frequent Exposure to X-Rays Increase Their Risk of Cancer? Spine 45:1200\u0026ndash;1207. https://doi.org/10.1097/BRS.0000000000003507\u003c/li\u003e\n\u003cli\u003eMaizlin ZV, Vos PM (2012) How to measure scapholunate and Cobb\u0026rsquo;s angles on MRI and CT. J Digit Imaging 25:558\u0026ndash;561. https://doi.org/10.1007/s10278-011-9438-2\u003c/li\u003e\n\u003cli\u003eJohnson MA, Gohel S, Mitchell SL, Flynn JJM, Baldwin KD (2021) Entire-spine Magnetic Resonance Imaging Findings and Costs in Children With Presumed Adolescent Idiopathic Scoliosis. J Pediatr Orthop 41:585\u0026ndash;590. https://doi.org/10.1097/BPO.0000000000001943\u003c/li\u003e\n\u003cli\u003eKaiser R, Behrbalk E, Walsh M, Waldauf P, Perez Romera AB, Mehdian H (2017) Can MRI Predict Flexibility in Scheuermann Kyphosis Patients? Clin Spine Surg 30:E938\u0026ndash;E941. https://doi.org/10.1097/BSD.0000000000000346\u003c/li\u003e\n\u003cli\u003eEOS is a low-dose radiation alternative to X-rays and CT. In: Hospital for Special Surgery. https://www.hss.edu/condition-list_eos-imaging.asp. Accessed 5 Jun 2024\u003c/li\u003e\n\u003cli\u003eWade R, Yang H, McKenna C, Faria R, Gummerson N, Woolacott N (2012) A systematic review of the clinical effectiveness of EOS 2D/3D X-ray imaging system. Eur Spine J 22:296\u0026ndash;304. https://doi.org/10.1007/s00586-012-2469-7\u003c/li\u003e\n\u003cli\u003eRose LD, Williams R, Ajayi B, Abdalla M, Bernard J, Bishop T, Papadakos N, Lui DF (2023) Reducing radiation exposure and cancer risk for children with scoliosis: EOS the new gold standard. Spine Deformity 11:847. https://doi.org/10.1007/s43390-023-00653-6\u003c/li\u003e\n\u003cli\u003eIlharreborde B, Ferrero E, Alison M, Mazda K (2016) EOS microdose protocol for the radiological follow-up of adolescent idiopathic scoliosis. Eur Spine J 25.: https://doi.org/10.1007/s00586-015-3960-8\u003c/li\u003e\n\u003cli\u003eAugust DAP to mSv converter - radiography. https://www.dosewizard.com/2019/08/effective-dose-calculator-radiography.html. Accessed 28 Feb 2024\u003c/li\u003e\n\u003cli\u003eX-Ray Risk Calculator. Available at: https://www.xrayrisk.com. Accessed 28 Feb 2024.\u003c/li\u003e\n\u003cli\u003eThorne MC (2003) Background radiation: natural and man-made. J Radiol Prot 23.: https://doi.org/10.1088/0952-4746/23/1/302\u003c/li\u003e\n\u003cli\u003eSimony A, Hansen EJ, Christensen SB, Carreon LY, Andersen MO (2016) Incidence of cancer in adolescent idiopathic scoliosis patients treated 25 years previously. Eur Spine J 25:3366\u0026ndash;3370. https://doi.org/10.1007/s00586-016-4747-2\u003c/li\u003e\n\u003cli\u003eRecommendations | The EOS 2D/3D imaging system | Guidance | NICE. Available at: https://www.nice.org.uk/guidance/dg1. Accessed 28 Feb 2024.\u003c/li\u003e\n\u003cli\u003eIR(ME)R: Implications for clinical practice in diagnostic imaging, interventional radiology and diagnostic nuclear medicine. https://www.rcr.ac.uk/our-services/all-our-publications/clinical-radiology-publications/ir-me-r-implications-for-clinical-practice-in-diagnostic-imaging-interventional-radiology-and-diagnostic-nuclear-medicine/. Accessed 28 Feb 2024\u003c/li\u003e\n\u003cli\u003ePedersen PH, Petersen AG, \u0026Oslash;stgaard SE, Tvedebrink T, Eiskj\u0026aelig;r SP (2018) EOS Micro-dose Protocol: First Full-spine Radiation Dose Measurements in Anthropomorphic Phantoms and Comparisons with EOS Standard-dose and Conventional Digital Radiology. Spine 43.: https://doi.org/10.1097/BRS.0000000000002696\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-6315925/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6315925/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003ePurpose:\u003c/strong\u003e Children with scoliosis are exposed to significant lifetime radiation doses because of multiple imaging studies as part of their investigation and treatment. EOS scanning has been shown to significantly reduce overall radiation and cancer risk. To reduce radiation further, a microdose setting can be used on the EOS scanner. This study aimed to quantify the reduction in radiation dose and assess image quality compared to the standard EOS settings.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods:\u003c/strong\u003e A consecutive group of paediatric patients who received both a standard EOS dose and a microdose EOS scan for investigating their scoliosis within a 6-month period. The radiation doses were compared, and cancer risk was estimated using a validated risk calculator. Assessment of image quality was blindly evaluated by six surgeons, using a five-point visual analogue scale (VAS) between standard and microdose studies.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e Twenty-five children who received both studies within a six month period were included, median age 13 (IQR 4). The total doses in the standard EOS group were 0.0895 mSv (additional lifetime cancer risk per study: 0.00197%); compared to the microdose group of 0.0167 mSv (additional lifetime cancer risk per study: 0.00037%) (p \u0026lt;.0001). Image quality VAS was not statistically different between settings (standard: 4.2, microdose 4.0) (p = 0.074).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion:\u003c/strong\u003e \u0026nbsp;Microdose EOS resulted in a five-fold reduction in radiation dose compared to Standard dose EOS and a subsequent 532% decrease in lifetime cancer risk per study. This builds on the fact that Standard dose EOS already carries five times less radiation and cancer risk than plain films. Therefore, compared to traditional radiographs, using a microdose EOS would result in a 40-fold reduction in radiation dose, and a large lifetime reduction in iatrogenic cancer risk. Microdose EOS was found to be both safe and accurate for purpose. A larger study is needed to support these findings.\u003c/p\u003e","manuscriptTitle":"Microdose EOS Imaging: Just as Good, and Safer","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-20 09:48:49","doi":"10.21203/rs.3.rs-6315925/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"3796f76a-5bcd-49c9-a4d3-a890cd2e05e9","owner":[],"postedDate":"May 20th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-22T08:43:24+00:00","versionOfRecord":[],"versionCreatedAt":"2025-05-20 09:48:49","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6315925","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6315925","identity":"rs-6315925","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}