Jeremy P. M. Flanagan, William H. F. Udovenya, Melvin A. Astrahan, Daniel McKay, Claire Phillips, John D. McKenzie, Roderick O’Day, Lotte S. Fog
{"title":"Quantifying the effect of eccentric ruthenium plaque placement on tumor volume dose","authors":"Jeremy P. M. Flanagan, William H. F. Udovenya, Melvin A. Astrahan, Daniel McKay, Claire Phillips, John D. McKenzie, Roderick O’Day, Lotte S. Fog","doi":"10.5114/jcb.2023.133614","DOIUrl":null,"url":null,"abstract":"<b>Purpose:</b><br/>Ruthenium-106 brachytherapy is a common treatment for small to medium-sized uveal melanomas. In certain clinical contexts, plaques may be placed eccentrically to tumor center. The effect of plaque decentration, a common radiation dose measurement in radiotherapy: D<sub>98%</sub>, the percentage of the tumor volume receiving at least 98% of the prescribed dose (a commonly used term in radiation oncology), is unknown. We investigated this using two commonly used plaques (CCA and CCB; Eckert & Ziegler, BEBIG GmbH) <i>in silico</i>.<br/><br/><b>Material and methods:</b><br/>Using a Plaque Simulator™ (Eye Physics) plaque modelling software, treatment time required to deliver 100 Gy D<sub>98%</sub> with central plaque placement was calculated for both plaque models, treating tumors with basal dimensions of 10 mm (CCB plaque only) and 7 mm (CCA and CCB plaques), and a range of thicknesses. D<sub>98%</sub> was calculated for plaque-tumor edge distances of 0-5 mm. Additionally, we defined minimum plaque-tumor edge distances, at which D<sub>98%</sub> fell by 10% and 5% (safety margins).<br/><br/><b>Results:</b><br/>D<sub>98%</sub> decreased as plaque-tumor edge distance decreased, i.e. as plaque eccentricity increased. Minor (< 1 mm) plaque decentration caused minimal D<sub>98%</sub> changes across tumor thicknesses. Safety margins did not follow a consistent pattern.<br/><br/><b>Conclusions:</b><br/>Eccentric plaque placement reduces the radiation dose delivered to choroidal tumors. Both tumor (thickness, diameter) and plaque (size, location) characteristics are important D<sub>98%</sub> modulators. Further investigation of the effect of these characteristics and dose to organs at risk is essential.<br/><br/>","PeriodicalId":51305,"journal":{"name":"Journal of Contemporary Brachytherapy","volume":null,"pages":null},"PeriodicalIF":1.1000,"publicationDate":"2023-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Contemporary Brachytherapy","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.5114/jcb.2023.133614","RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"ONCOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Purpose: Ruthenium-106 brachytherapy is a common treatment for small to medium-sized uveal melanomas. In certain clinical contexts, plaques may be placed eccentrically to tumor center. The effect of plaque decentration, a common radiation dose measurement in radiotherapy: D98%, the percentage of the tumor volume receiving at least 98% of the prescribed dose (a commonly used term in radiation oncology), is unknown. We investigated this using two commonly used plaques (CCA and CCB; Eckert & Ziegler, BEBIG GmbH) in silico.
Material and methods: Using a Plaque Simulator™ (Eye Physics) plaque modelling software, treatment time required to deliver 100 Gy D98% with central plaque placement was calculated for both plaque models, treating tumors with basal dimensions of 10 mm (CCB plaque only) and 7 mm (CCA and CCB plaques), and a range of thicknesses. D98% was calculated for plaque-tumor edge distances of 0-5 mm. Additionally, we defined minimum plaque-tumor edge distances, at which D98% fell by 10% and 5% (safety margins).
Results: D98% decreased as plaque-tumor edge distance decreased, i.e. as plaque eccentricity increased. Minor (< 1 mm) plaque decentration caused minimal D98% changes across tumor thicknesses. Safety margins did not follow a consistent pattern.
Conclusions: Eccentric plaque placement reduces the radiation dose delivered to choroidal tumors. Both tumor (thickness, diameter) and plaque (size, location) characteristics are important D98% modulators. Further investigation of the effect of these characteristics and dose to organs at risk is essential.
期刊介绍:
The “Journal of Contemporary Brachytherapy” is an international and multidisciplinary journal that will publish papers of original research as well as reviews of articles. Main subjects of the journal include: clinical brachytherapy, combined modality treatment, advances in radiobiology, hyperthermia and tumour biology, as well as physical aspects relevant to brachytherapy, particularly in the field of imaging, dosimetry and radiation therapy planning. Original contributions will include experimental studies of combined modality treatment, tumor sensitization and normal tissue protection, molecular radiation biology, and clinical investigations of cancer treatment in brachytherapy. Another field of interest will be the educational part of the journal.