John Ginn PhD , Sai Duriseti MD, PhD , Thomas Mazur PhD , Matthew Spraker MD , James Kavanaugh PhD
{"title":"空间分割放射治疗期间对准误差的剂量累积评估","authors":"John Ginn PhD , Sai Duriseti MD, PhD , Thomas Mazur PhD , Matthew Spraker MD , James Kavanaugh PhD","doi":"10.1016/j.prro.2023.11.015","DOIUrl":null,"url":null,"abstract":"<div><h3>Purpose</h3><p>Spatially fractionated radiation therapy (SFRT) techniques produce high-dose peaks and low-dose valleys within a tumor. Lattice stereotactic body radiation therapy<span> (SBRT) is a form a SFRT delivered across 5 fractions. Because of the high spatial dose gradients associated with SFRT, it is critical for fractionated SFRT patients to be aligned correctly for treatment. Here we investigate the dosimetric effect of daily alignment uncertainty through a dose accumulation study.</span></p></div><div><h3>Methods and Materials</h3><p><span><span>Dose accumulation was retrospectively performed for 10 patients enrolled on a phase 1 trial. Lattice stereotactic body radiation therapy was completed in 5 fractions with 20 Gy prescribed to the entire tumor and a simultaneous integrated boost of 66.7 Gy prescribed to a set of regularly spaced high-dose spheres. Daily alignment error was quantified through manually selected landmarks in both the planning computed tomography scan and daily </span>cone beam computed tomography. The dosimetric effect of alignment errors was quantified by </span>translating<span> the isocenter in the treatment planning system by the daily average alignment error. Large errors were simulated by translating isocenter 5 and 10 mm for 1 and 2 fractions, independently assessing errors in the superior-inferior and axial directions. The reduction of dose gradients was quantified using the dose ratio (DR) of the mean dose in the high-dose and low-dose spheres.</span></p></div><div><h3>Results</h3><p>The average alignment error was 1.8 mm across the patient population resulting in minor smoothing of the high- and low-dose distributions in the dose accumulation. Quantitatively, the DR decreased from 3.42 to 3.32 (<em>P</em> = .093) in the dose accumulation study. The simulated worst case was an inferior-superior shift of 10 mm for 2 fractions where the average DR decreased to 2.72 (<em>P</em> = .0001).</p></div><div><h3>Conclusions</h3><p>The dose accumulation study revealed on average DR only decreased from 3.42 to 3.32. However, setup errors >5 mm resulted in larger dosimetric degradation, reflecting a larger effect for individual high-dose spheres within regions exhibiting larger displacements.</p></div>","PeriodicalId":54245,"journal":{"name":"Practical Radiation Oncology","volume":null,"pages":null},"PeriodicalIF":3.4000,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"A Dose Accumulation Assessment of Alignment Errors During Spatially Fractionated Radiation Therapy\",\"authors\":\"John Ginn PhD , Sai Duriseti MD, PhD , Thomas Mazur PhD , Matthew Spraker MD , James Kavanaugh PhD\",\"doi\":\"10.1016/j.prro.2023.11.015\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><h3>Purpose</h3><p>Spatially fractionated radiation therapy (SFRT) techniques produce high-dose peaks and low-dose valleys within a tumor. Lattice stereotactic body radiation therapy<span> (SBRT) is a form a SFRT delivered across 5 fractions. Because of the high spatial dose gradients associated with SFRT, it is critical for fractionated SFRT patients to be aligned correctly for treatment. Here we investigate the dosimetric effect of daily alignment uncertainty through a dose accumulation study.</span></p></div><div><h3>Methods and Materials</h3><p><span><span>Dose accumulation was retrospectively performed for 10 patients enrolled on a phase 1 trial. Lattice stereotactic body radiation therapy was completed in 5 fractions with 20 Gy prescribed to the entire tumor and a simultaneous integrated boost of 66.7 Gy prescribed to a set of regularly spaced high-dose spheres. Daily alignment error was quantified through manually selected landmarks in both the planning computed tomography scan and daily </span>cone beam computed tomography. The dosimetric effect of alignment errors was quantified by </span>translating<span> the isocenter in the treatment planning system by the daily average alignment error. Large errors were simulated by translating isocenter 5 and 10 mm for 1 and 2 fractions, independently assessing errors in the superior-inferior and axial directions. The reduction of dose gradients was quantified using the dose ratio (DR) of the mean dose in the high-dose and low-dose spheres.</span></p></div><div><h3>Results</h3><p>The average alignment error was 1.8 mm across the patient population resulting in minor smoothing of the high- and low-dose distributions in the dose accumulation. Quantitatively, the DR decreased from 3.42 to 3.32 (<em>P</em> = .093) in the dose accumulation study. The simulated worst case was an inferior-superior shift of 10 mm for 2 fractions where the average DR decreased to 2.72 (<em>P</em> = .0001).</p></div><div><h3>Conclusions</h3><p>The dose accumulation study revealed on average DR only decreased from 3.42 to 3.32. However, setup errors >5 mm resulted in larger dosimetric degradation, reflecting a larger effect for individual high-dose spheres within regions exhibiting larger displacements.</p></div>\",\"PeriodicalId\":54245,\"journal\":{\"name\":\"Practical Radiation Oncology\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":3.4000,\"publicationDate\":\"2024-07-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Practical Radiation Oncology\",\"FirstCategoryId\":\"3\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S1879850023003429\",\"RegionNum\":3,\"RegionCategory\":\"医学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"ONCOLOGY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Practical Radiation Oncology","FirstCategoryId":"3","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1879850023003429","RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ONCOLOGY","Score":null,"Total":0}
A Dose Accumulation Assessment of Alignment Errors During Spatially Fractionated Radiation Therapy
Purpose
Spatially fractionated radiation therapy (SFRT) techniques produce high-dose peaks and low-dose valleys within a tumor. Lattice stereotactic body radiation therapy (SBRT) is a form a SFRT delivered across 5 fractions. Because of the high spatial dose gradients associated with SFRT, it is critical for fractionated SFRT patients to be aligned correctly for treatment. Here we investigate the dosimetric effect of daily alignment uncertainty through a dose accumulation study.
Methods and Materials
Dose accumulation was retrospectively performed for 10 patients enrolled on a phase 1 trial. Lattice stereotactic body radiation therapy was completed in 5 fractions with 20 Gy prescribed to the entire tumor and a simultaneous integrated boost of 66.7 Gy prescribed to a set of regularly spaced high-dose spheres. Daily alignment error was quantified through manually selected landmarks in both the planning computed tomography scan and daily cone beam computed tomography. The dosimetric effect of alignment errors was quantified by translating the isocenter in the treatment planning system by the daily average alignment error. Large errors were simulated by translating isocenter 5 and 10 mm for 1 and 2 fractions, independently assessing errors in the superior-inferior and axial directions. The reduction of dose gradients was quantified using the dose ratio (DR) of the mean dose in the high-dose and low-dose spheres.
Results
The average alignment error was 1.8 mm across the patient population resulting in minor smoothing of the high- and low-dose distributions in the dose accumulation. Quantitatively, the DR decreased from 3.42 to 3.32 (P = .093) in the dose accumulation study. The simulated worst case was an inferior-superior shift of 10 mm for 2 fractions where the average DR decreased to 2.72 (P = .0001).
Conclusions
The dose accumulation study revealed on average DR only decreased from 3.42 to 3.32. However, setup errors >5 mm resulted in larger dosimetric degradation, reflecting a larger effect for individual high-dose spheres within regions exhibiting larger displacements.
期刊介绍：
The overarching mission of Practical Radiation Oncology is to improve the quality of radiation oncology practice. PRO''s purpose is to document the state of current practice, providing background for those in training and continuing education for practitioners, through discussion and illustration of new techniques, evaluation of current practices, and publication of case reports. PRO strives to provide its readers content that emphasizes knowledge "with a purpose." The content of PRO includes:
Original articles focusing on patient safety, quality measurement, or quality improvement initiatives
Original articles focusing on imaging, contouring, target delineation, simulation, treatment planning, immobilization, organ motion, and other practical issues
ASTRO guidelines, position papers, and consensus statements
Essays that highlight enriching personal experiences in caring for cancer patients and their families.
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