Johannes Kusters, René Monshouwer, Peter Koopmans, Markus Wendling, Ellen Brunenberg, Linda Kerkmeijer, Erik van der Bijl, Martijn Kusters
{"title":"磁共振成像引导放射治疗中的前列腺运动及其对边缘的影响。","authors":"Johannes Kusters, René Monshouwer, Peter Koopmans, Markus Wendling, Ellen Brunenberg, Linda Kerkmeijer, Erik van der Bijl, Martijn Kusters","doi":"10.1007/s00066-024-02346-z","DOIUrl":null,"url":null,"abstract":"<p><strong>Purpose: </strong>This study focused on reducing the margin for prostate cancer treatment using magnetic resonance imaging-guided radiotherapy by investigating the intrafractional motion of the prostate and different motion-mitigation strategies.</p><p><strong>Methods: </strong>We retrospectively analyzed intrafractional prostate motion in 77 patients with low- to intermediate-risk prostate cancer treated with five fractions of 7.25 Gy on a 1.5 T magnetic resonance linear accelerator. Systematic drift motion was observed and described by an intrafractional motion model. The planning target volume (PTV) margin was calculated in a cohort of 77 patients and prospectively evaluated for geometric coverage in a separate cohort of 24 patients.</p><p><strong>Results: </strong>The intrafractional model showed that the prostate position starts out of equilibrium for the anterior-posterior (-1.8 ± 3.1 mm) and superior-inferior (1.7 ± 2.6 mm) directions, with relaxation times of 12 and 15 min, respectively. Position verification scans are acquired at 30 min on average. At that time, the transient drift motion becomes indistinguishable from the residual random intrafractional motion. PTV margins can be reduced to 1.8 mm (left-right), 3.2 mm (anterior-posterior), and 2.9 mm (superior-inferior). Evaluation of the overlap with the clinical target volume (CTV) was performed for a total of 120 fractions of 24 patients. The overlap range between the CTV and the PTV was 93-100% and the applied 3‑mm PTV margin for the CTV had a 99.5% averaged geometric overlap for all patients.</p><p><strong>Conclusion: </strong>A PTV margin reduction to 3 mm is feasible. A patient-specific approach could reduce the margins further.</p>","PeriodicalId":21998,"journal":{"name":"Strahlentherapie und Onkologie","volume":" ","pages":""},"PeriodicalIF":2.7000,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Prostate motion in magnetic resonance imaging-guided radiotherapy and its impact on margins.\",\"authors\":\"Johannes Kusters, René Monshouwer, Peter Koopmans, Markus Wendling, Ellen Brunenberg, Linda Kerkmeijer, Erik van der Bijl, Martijn Kusters\",\"doi\":\"10.1007/s00066-024-02346-z\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p><strong>Purpose: </strong>This study focused on reducing the margin for prostate cancer treatment using magnetic resonance imaging-guided radiotherapy by investigating the intrafractional motion of the prostate and different motion-mitigation strategies.</p><p><strong>Methods: </strong>We retrospectively analyzed intrafractional prostate motion in 77 patients with low- to intermediate-risk prostate cancer treated with five fractions of 7.25 Gy on a 1.5 T magnetic resonance linear accelerator. Systematic drift motion was observed and described by an intrafractional motion model. The planning target volume (PTV) margin was calculated in a cohort of 77 patients and prospectively evaluated for geometric coverage in a separate cohort of 24 patients.</p><p><strong>Results: </strong>The intrafractional model showed that the prostate position starts out of equilibrium for the anterior-posterior (-1.8 ± 3.1 mm) and superior-inferior (1.7 ± 2.6 mm) directions, with relaxation times of 12 and 15 min, respectively. Position verification scans are acquired at 30 min on average. At that time, the transient drift motion becomes indistinguishable from the residual random intrafractional motion. PTV margins can be reduced to 1.8 mm (left-right), 3.2 mm (anterior-posterior), and 2.9 mm (superior-inferior). Evaluation of the overlap with the clinical target volume (CTV) was performed for a total of 120 fractions of 24 patients. The overlap range between the CTV and the PTV was 93-100% and the applied 3‑mm PTV margin for the CTV had a 99.5% averaged geometric overlap for all patients.</p><p><strong>Conclusion: </strong>A PTV margin reduction to 3 mm is feasible. 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Prostate motion in magnetic resonance imaging-guided radiotherapy and its impact on margins.
Purpose: This study focused on reducing the margin for prostate cancer treatment using magnetic resonance imaging-guided radiotherapy by investigating the intrafractional motion of the prostate and different motion-mitigation strategies.
Methods: We retrospectively analyzed intrafractional prostate motion in 77 patients with low- to intermediate-risk prostate cancer treated with five fractions of 7.25 Gy on a 1.5 T magnetic resonance linear accelerator. Systematic drift motion was observed and described by an intrafractional motion model. The planning target volume (PTV) margin was calculated in a cohort of 77 patients and prospectively evaluated for geometric coverage in a separate cohort of 24 patients.
Results: The intrafractional model showed that the prostate position starts out of equilibrium for the anterior-posterior (-1.8 ± 3.1 mm) and superior-inferior (1.7 ± 2.6 mm) directions, with relaxation times of 12 and 15 min, respectively. Position verification scans are acquired at 30 min on average. At that time, the transient drift motion becomes indistinguishable from the residual random intrafractional motion. PTV margins can be reduced to 1.8 mm (left-right), 3.2 mm (anterior-posterior), and 2.9 mm (superior-inferior). Evaluation of the overlap with the clinical target volume (CTV) was performed for a total of 120 fractions of 24 patients. The overlap range between the CTV and the PTV was 93-100% and the applied 3‑mm PTV margin for the CTV had a 99.5% averaged geometric overlap for all patients.
Conclusion: A PTV margin reduction to 3 mm is feasible. A patient-specific approach could reduce the margins further.
期刊介绍：
Strahlentherapie und Onkologie, published monthly, is a scientific journal that covers all aspects of oncology with focus on radiooncology, radiation biology and radiation physics. The articles are not only of interest to radiooncologists but to all physicians interested in oncology, to radiation biologists and radiation physicists. The journal publishes original articles, review articles and case studies that are peer-reviewed. It includes scientific short communications as well as a literature review with annotated articles that inform the reader on new developments in the various disciplines concerned and hence allow for a sound overview on the latest results in radiooncology research.
Founded in 1912, Strahlentherapie und Onkologie is the oldest oncological journal in the world. Today, contributions are published in English and German. All articles have English summaries and legends. The journal is the official publication of several scientific radiooncological societies and publishes the relevant communications of these societies.
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