Duration-dependent margins for prostate radiotherapy—a practical motion mitigation strategy

Pei Ping Eric Pang; Kellie Knight; Sung Yong Park; Weixiang Lian; Zubin Master; Marilyn Baird; Jason Wei Xiang  Chan; Michael Lian Chek Wang; Terence Wee Kiat Tan; Melvin L.K. Chua; Eu Tiong Chua; Wen Shen Looi; Wen Long Nei; Jeffrey Kit Loong Tuan

doi:10.1007/s00066-019-01558-y

Duration-dependent margins for prostate radiotherapy—a practical motion mitigation strategy

Pei Ping Eric Pang, Kellie Knight, Sung Yong Park, Weixiang Lian, Zubin Master, Marilyn Baird, Jason Wei Xiang Chan, Michael Lian Chek Wang, Terence Wee Kiat Tan, Melvin L.K. Chua, Eu Tiong Chua, Wen Shen Looi, Wen Long Nei, Jeffrey Kit Loong Tuan

Medical Imaging & Radiation Sciences

Research output: Contribution to journal › Article › Research › peer-review

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 (2.5P+ 1.64((σ2+ σp 2)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 0.76mm Inferior (Inf), 0mm Lateral (Lat) and 0.94mm Posterior (Post) at the 15th minute. A minimum margin expansion of 2.42mm (Superior/Inf), 1.02mm (Left/Right) and 2.65mm (Anterior/ Post) was required for an 8-minute treatment compared to 4.29mm (Sup/Inf), 1.84mm (Lt/Rt) and 4.63mm (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).

Original language	English
Pages (from-to)	657-663
Number of pages	7
Journal	Strahlentherapie Und Onkologie
Volume	196
Issue number	7
DOIs	https://doi.org/10.1007/s00066-019-01558-y
Publication status	Published - Jul 2020

Keywords

Intra-fractional prostate displacement
Prostate cancer
Real-time tracking
Transperineal ultrasound
Margins

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.1007/s00066-019-01558-y

Cite this

Pang, P. P. E., Knight, K., Park, S. Y., Lian, W., Master, Z., Baird, M., Chan, J. W. X., Wang, M. L. C., Tan, T. W. K., Chua, M. L. K., Chua, E. T., Looi, W. S., Nei, W. L., & Tuan, J. K. L. (2020). Duration-dependent margins for prostate radiotherapy—a practical motion mitigation strategy. Strahlentherapie Und Onkologie, 196(7), 657-663. https://doi.org/10.1007/s00066-019-01558-y

@article{3bff5b4b98c0463ea69c53593d42337c,

title = "Duration-dependent margins for prostate radiotherapy—a practical motion mitigation strategy",

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{\textregistered} system. A total of 1745 monitoring sessions were analysed. Van Herk{\textquoteright}s margin recipe (2.5P+ 1.64((σ2+ σp 2)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 0.76mm Inferior (Inf), 0mm Lateral (Lat) and 0.94mm Posterior (Post) at the 15th minute. A minimum margin expansion of 2.42mm (Superior/Inf), 1.02mm (Left/Right) and 2.65mm (Anterior/ Post) was required for an 8-minute treatment compared to 4.29mm (Sup/Inf), 1.84mm (Lt/Rt) and 4.63mm (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).",

keywords = "Intra-fractional prostate displacement, Prostate cancer, Real-time tracking, Transperineal ultrasound, Margins",

author = "Pang, {Pei Ping Eric} and Kellie Knight and Park, {Sung Yong} and Weixiang Lian and Zubin Master and Marilyn Baird and Chan, {Jason Wei Xiang} and Wang, {Michael Lian Chek} and Tan, {Terence Wee Kiat} and Chua, {Melvin L.K.} and Chua, {Eu Tiong} and Looi, {Wen Shen} and Nei, {Wen Long} and Tuan, {Jeffrey Kit Loong}",

year = "2020",

month = jul,

doi = "10.1007/s00066-019-01558-y",

language = "English",

volume = "196",

pages = "657--663",

journal = "Strahlentherapie Und Onkologie",

issn = "0179-7158",

publisher = "Springer-Verlag London Ltd.",

number = "7",

}

TY - JOUR

T1 - Duration-dependent margins for prostate radiotherapy—a practical motion mitigation strategy

AU - Pang, Pei Ping Eric

AU - Knight, Kellie

AU - Park, Sung Yong

AU - Lian, Weixiang

AU - Master, Zubin

AU - Baird, Marilyn

AU - Chan, Jason Wei Xiang

AU - Wang, Michael Lian Chek

AU - Tan, Terence Wee Kiat

AU - Chua, Melvin L.K.

AU - Chua, Eu Tiong

AU - Looi, Wen Shen

AU - Nei, Wen Long

AU - Tuan, Jeffrey Kit Loong

PY - 2020/7

Y1 - 2020/7

N2 - 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 (2.5P+ 1.64((σ2+ σp 2)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 0.76mm Inferior (Inf), 0mm Lateral (Lat) and 0.94mm Posterior (Post) at the 15th minute. A minimum margin expansion of 2.42mm (Superior/Inf), 1.02mm (Left/Right) and 2.65mm (Anterior/ Post) was required for an 8-minute treatment compared to 4.29mm (Sup/Inf), 1.84mm (Lt/Rt) and 4.63mm (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).

AB - 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 (2.5P+ 1.64((σ2+ σp 2)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 0.76mm Inferior (Inf), 0mm Lateral (Lat) and 0.94mm Posterior (Post) at the 15th minute. A minimum margin expansion of 2.42mm (Superior/Inf), 1.02mm (Left/Right) and 2.65mm (Anterior/ Post) was required for an 8-minute treatment compared to 4.29mm (Sup/Inf), 1.84mm (Lt/Rt) and 4.63mm (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).

KW - Intra-fractional prostate displacement

KW - Prostate cancer

KW - Real-time tracking

KW - Transperineal ultrasound

KW - Margins

U2 - 10.1007/s00066-019-01558-y

DO - 10.1007/s00066-019-01558-y

M3 - Article

SN - 0179-7158

VL - 196

SP - 657

EP - 663

JO - Strahlentherapie Und Onkologie

JF - Strahlentherapie Und Onkologie

IS - 7

ER -