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Pang EPP, Knight K, Park SY, Lian W, Master Z, Baird M, Chan JWX, Wang MLC, Tan TWK, Chua MLK, Chua ET, Looi WS, Nei WL, Tuan JKL. Duration-dependent margins for prostate radiotherapy-a practical motion mitigation strategy. Strahlenther Onkol 2020; 196:657-663. [PMID: 31932995 DOI: 10.1007/s00066-019-01558-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 11/21/2019] [Indexed: 11/24/2022]
Abstract
BACKGROUND AND OBJECTIVE The magnitude of intra-fractional prostate displacement (change from initial position over time) is associated with the duration of the patient lying on the radiotherapy treatment couch. This study reports a minute-by-minute association and calculates the impact of this displacement on duration-dependent margins using real-time intra-fractional position data monitored by four-dimensional transperineal ultrasound (4D TPUS). MATERIALS AND METHODS A total of 55 patients were recruited prospectively. Intra-fractional position of the prostate was monitored in real-time using a 4D TPUS Clarity® system. A total of 1745 monitoring sessions were analysed. Van Herk's margin recipe (2.5∑ + 1.64((σ2 + σp2)1/2 - σp)) was used to estimate the duration-dependant margins for every minute, up to the 15th minute. Linear regression analysis was then performed on the overall margins against time and direction. RESULTS The mean intra-fractional position was 0.76 mm Inferior (Inf), 0 mm Lateral (Lat) and 0.94 mm Posterior (Post) at the 15th minute. A minimum margin expansion of 2.42 mm (Superior/Inf), 1.02 mm (Left/Right) and 2.65 mm (Anterior/Post) was required for an 8‑minute treatment compared to 4.29 mm (Sup/Inf), 1.84 mm (Lt/Rt) and 4.63 mm (Ant/Post) for a 15-minute treatment. The required margin expansion increased linearly (R2 = 0.99) in all directions (p < 0.01). However, while there was no statistically significant difference (p = 0.10) in the required margin expansion in the Sup/Inf and Ant/Post directions respective of the time duration, the margins were much bigger compared to those in the Lt/Rt direction (p < 0.01). CONCLUSION We report our experience in deriving the minimum duration-dependant margin to generate the required planning target volume for prostate radiotherapy. The required margin increases linearly in all directions within the 15-min duration; thus, the margin will depend on the duration of the technique chosen (IMRT/VMAT/3DCRT/proton).
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Affiliation(s)
- Eric Pei Ping Pang
- Division of Radiation Oncology, National Cancer Centre Singapore, 11 Hospital Crescent, 169610, Singapore, Singapore. .,Faculty of Medicine, Nursing and Health Sciences, Department of Medical Imaging & Radiation Sciences, Monash University, Wellington Road, Clayton VIC, 3800, Melbourne, Australia.
| | - Kellie Knight
- Faculty of Medicine, Nursing and Health Sciences, Department of Medical Imaging & Radiation Sciences, Monash University, Wellington Road, Clayton VIC, 3800, Melbourne, Australia
| | - Sung Yong Park
- Division of Radiation Oncology, National Cancer Centre Singapore, 11 Hospital Crescent, 169610, Singapore, Singapore
| | - Weixiang Lian
- Division of Radiation Oncology, National Cancer Centre Singapore, 11 Hospital Crescent, 169610, Singapore, Singapore
| | - Zubin Master
- Division of Radiation Oncology, National Cancer Centre Singapore, 11 Hospital Crescent, 169610, Singapore, Singapore
| | - Marilyn Baird
- Faculty of Medicine, Nursing and Health Sciences, Department of Medical Imaging & Radiation Sciences, Monash University, Wellington Road, Clayton VIC, 3800, Melbourne, Australia
| | - Jason Wei Xiang Chan
- Division of Radiation Oncology, National Cancer Centre Singapore, 11 Hospital Crescent, 169610, Singapore, Singapore
| | - Michael Lian Chek Wang
- Division of Radiation Oncology, National Cancer Centre Singapore, 11 Hospital Crescent, 169610, Singapore, Singapore.,Duke-NUS Graduate Medical School, 8 College Road, 169857, Singapore, Singapore
| | - Terence Wee Kiat Tan
- Division of Radiation Oncology, National Cancer Centre Singapore, 11 Hospital Crescent, 169610, Singapore, Singapore.,Duke-NUS Graduate Medical School, 8 College Road, 169857, Singapore, Singapore
| | - Melvin L K Chua
- Division of Radiation Oncology, National Cancer Centre Singapore, 11 Hospital Crescent, 169610, Singapore, Singapore.,Duke-NUS Graduate Medical School, 8 College Road, 169857, Singapore, Singapore.,Division of Medical Sciences, National Cancer Centre Singapore, 11 Hospital Crescent, 169610, Singapore, Singapore
| | - Eu Tiong Chua
- Division of Radiation Oncology, National Cancer Centre Singapore, 11 Hospital Crescent, 169610, Singapore, Singapore.,Duke-NUS Graduate Medical School, 8 College Road, 169857, Singapore, Singapore
| | - Wen Shen Looi
- Division of Radiation Oncology, National Cancer Centre Singapore, 11 Hospital Crescent, 169610, Singapore, Singapore.,Duke-NUS Graduate Medical School, 8 College Road, 169857, Singapore, Singapore
| | - Wen Long Nei
- Division of Radiation Oncology, National Cancer Centre Singapore, 11 Hospital Crescent, 169610, Singapore, Singapore.,Duke-NUS Graduate Medical School, 8 College Road, 169857, Singapore, Singapore
| | - Jeffrey Kit Loong Tuan
- Division of Radiation Oncology, National Cancer Centre Singapore, 11 Hospital Crescent, 169610, Singapore, Singapore.,Duke-NUS Graduate Medical School, 8 College Road, 169857, Singapore, Singapore
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