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Title: Exploring the Margin Recipe for Online Adaptive Radiation Therapy for Intermediate-Risk Prostate Cancer: An Intrafractional Seminal Vesicles Motion Analysis

Abstract

Purpose: To provide a benchmark for seminal vesicle (SV) margin selection to account for intrafractional motion and to investigate the effectiveness of 2 motion surrogates in predicting intrafractional SV coverage. Methods and Materials: Fifteen prostate patients were studied. Each patient had 5 pairs (1 patient had 4 pairs) of pretreatment and posttreatment cone beam CTs (CBCTs). Each pair of CBCTs was registered on the basis of prostate fiducial markers. All pretreatment SVs were expanded with 1-, 2-, 3-, 4-, 5-, and 8-mm isotropic margins to form a series of planning target volumes, and their intrafractional coverage to the posttreatment SV determined the “ground truth” for exact coverage. Two motion surrogates, the center of mass (COM) and the border of contour, were evaluated by the use of Pearson product-moment correlation coefficient and exponential fitting for predicting SV underdosage. Action threshold of each surrogate was calculated. The margin for each surrogate was calculated according to a traditional margin recipe. Results: Ninety-five percent posttreatment SV coverage was achieved in 9%, 53%, 73%, 86%, 95%, and 97% of fractions with 1-, 2-, 3-, 4-, 5-, and 8-mm margins, respectively. The 5-mm margins provided 95% intrafractional SV coverage in over 90% of fractions. The correlationmore » between the COM and border was weak, moderate, and strong in the left-right (L-R), anterior-posterior (A-P), and superior-inferior (S-I) directions, respectively. Exponential fitting gave the underdosage threshold of 4.5 and 7.0 mm for the COM and border. The Van Herk margin recipe recommended 0-, 0.5-, and 0.8-mm margins in the L-R, A-P, and S-I directions based on the COM, and 1.2-, 3.9-, and 2.5-mm margins based on the border. Conclusions: Five-millimeter isotropic margins for the SV constitute the minimum required to mitigate the intrafractional motion. Both the COM and the border are acceptable predictors for SV underdosage with 4.5- and 7.0-mm action threshold. Traditional margin based on the COM or border underestimates the margin.« less

Authors:
 [1];  [2];  [3];  [2];  [1]; ;  [1];  [2]
  1. Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States)
  2. (United States)
  3. Medical Physics Graduate Program, Duke University, Durham, North Carolina (United States)
Publication Date:
OSTI Identifier:
22649946
Resource Type:
Journal Article
Resource Relation:
Journal Name: International Journal of Radiation Oncology, Biology and Physics; Journal Volume: 98; Journal Issue: 2; Other Information: Copyright (c) 2017 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; CENTER-OF-MASS SYSTEM; COMPUTERIZED TOMOGRAPHY; FIDUCIAL MARKERS; GROUND TRUTH MEASUREMENTS; PATIENTS; PROSTATE; RADIATION HAZARDS; RADIOTHERAPY

Citation Formats

Sheng, Yang, E-mail: Yang.Sheng@duke.edu, Medical Physics Graduate Program, Duke University, Durham, North Carolina, Li, Taoran, Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, Pennsylvania, Lee, W. Robert, Yin, Fang-Fang, Wu, Q. Jackie, and Medical Physics Graduate Program, Duke University, Durham, North Carolina. Exploring the Margin Recipe for Online Adaptive Radiation Therapy for Intermediate-Risk Prostate Cancer: An Intrafractional Seminal Vesicles Motion Analysis. United States: N. p., 2017. Web. doi:10.1016/J.IJROBP.2017.02.089.
Sheng, Yang, E-mail: Yang.Sheng@duke.edu, Medical Physics Graduate Program, Duke University, Durham, North Carolina, Li, Taoran, Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, Pennsylvania, Lee, W. Robert, Yin, Fang-Fang, Wu, Q. Jackie, & Medical Physics Graduate Program, Duke University, Durham, North Carolina. Exploring the Margin Recipe for Online Adaptive Radiation Therapy for Intermediate-Risk Prostate Cancer: An Intrafractional Seminal Vesicles Motion Analysis. United States. doi:10.1016/J.IJROBP.2017.02.089.
Sheng, Yang, E-mail: Yang.Sheng@duke.edu, Medical Physics Graduate Program, Duke University, Durham, North Carolina, Li, Taoran, Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, Pennsylvania, Lee, W. Robert, Yin, Fang-Fang, Wu, Q. Jackie, and Medical Physics Graduate Program, Duke University, Durham, North Carolina. Thu . "Exploring the Margin Recipe for Online Adaptive Radiation Therapy for Intermediate-Risk Prostate Cancer: An Intrafractional Seminal Vesicles Motion Analysis". United States. doi:10.1016/J.IJROBP.2017.02.089.
@article{osti_22649946,
title = {Exploring the Margin Recipe for Online Adaptive Radiation Therapy for Intermediate-Risk Prostate Cancer: An Intrafractional Seminal Vesicles Motion Analysis},
author = {Sheng, Yang, E-mail: Yang.Sheng@duke.edu and Medical Physics Graduate Program, Duke University, Durham, North Carolina and Li, Taoran and Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, Pennsylvania and Lee, W. Robert and Yin, Fang-Fang and Wu, Q. Jackie and Medical Physics Graduate Program, Duke University, Durham, North Carolina},
abstractNote = {Purpose: To provide a benchmark for seminal vesicle (SV) margin selection to account for intrafractional motion and to investigate the effectiveness of 2 motion surrogates in predicting intrafractional SV coverage. Methods and Materials: Fifteen prostate patients were studied. Each patient had 5 pairs (1 patient had 4 pairs) of pretreatment and posttreatment cone beam CTs (CBCTs). Each pair of CBCTs was registered on the basis of prostate fiducial markers. All pretreatment SVs were expanded with 1-, 2-, 3-, 4-, 5-, and 8-mm isotropic margins to form a series of planning target volumes, and their intrafractional coverage to the posttreatment SV determined the “ground truth” for exact coverage. Two motion surrogates, the center of mass (COM) and the border of contour, were evaluated by the use of Pearson product-moment correlation coefficient and exponential fitting for predicting SV underdosage. Action threshold of each surrogate was calculated. The margin for each surrogate was calculated according to a traditional margin recipe. Results: Ninety-five percent posttreatment SV coverage was achieved in 9%, 53%, 73%, 86%, 95%, and 97% of fractions with 1-, 2-, 3-, 4-, 5-, and 8-mm margins, respectively. The 5-mm margins provided 95% intrafractional SV coverage in over 90% of fractions. The correlation between the COM and border was weak, moderate, and strong in the left-right (L-R), anterior-posterior (A-P), and superior-inferior (S-I) directions, respectively. Exponential fitting gave the underdosage threshold of 4.5 and 7.0 mm for the COM and border. The Van Herk margin recipe recommended 0-, 0.5-, and 0.8-mm margins in the L-R, A-P, and S-I directions based on the COM, and 1.2-, 3.9-, and 2.5-mm margins based on the border. Conclusions: Five-millimeter isotropic margins for the SV constitute the minimum required to mitigate the intrafractional motion. Both the COM and the border are acceptable predictors for SV underdosage with 4.5- and 7.0-mm action threshold. Traditional margin based on the COM or border underestimates the margin.},
doi = {10.1016/J.IJROBP.2017.02.089},
journal = {International Journal of Radiation Oncology, Biology and Physics},
number = 2,
volume = 98,
place = {United States},
year = {Thu Jun 01 00:00:00 EDT 2017},
month = {Thu Jun 01 00:00:00 EDT 2017}
}