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

Publication ,  Journal Article
Sheng, Y; Li, T; Lee, WR; Yin, F-F; Wu, QJ
Published in: Int J Radiat Oncol Biol Phys
June 1, 2017

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.

Duke Scholars

Published In

Int J Radiat Oncol Biol Phys

DOI

EISSN

1879-355X

Publication Date

June 1, 2017

Volume

98

Issue

2

Start / End Page

473 / 480

Location

United States

Related Subject Headings

  • Tumor Burden
  • Seminal Vesicles
  • Radiotherapy Planning, Computer-Assisted
  • Radiosurgery
  • Prostatic Neoplasms
  • Prostate
  • Oncology & Carcinogenesis
  • Movement
  • Motion
  • Male
 

Citation

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ICMJE
MLA
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Sheng, Y., Li, T., Lee, W. R., Yin, F.-F., & Wu, Q. J. (2017). Exploring the Margin Recipe for Online Adaptive Radiation Therapy for Intermediate-Risk Prostate Cancer: An Intrafractional Seminal Vesicles Motion Analysis. Int J Radiat Oncol Biol Phys, 98(2), 473–480. https://doi.org/10.1016/j.ijrobp.2017.02.089
Sheng, Yang, Taoran Li, W Robert Lee, Fang-Fang Yin, and Q Jackie Wu. “Exploring the Margin Recipe for Online Adaptive Radiation Therapy for Intermediate-Risk Prostate Cancer: An Intrafractional Seminal Vesicles Motion Analysis.Int J Radiat Oncol Biol Phys 98, no. 2 (June 1, 2017): 473–80. https://doi.org/10.1016/j.ijrobp.2017.02.089.
Sheng, Yang, et al. “Exploring the Margin Recipe for Online Adaptive Radiation Therapy for Intermediate-Risk Prostate Cancer: An Intrafractional Seminal Vesicles Motion Analysis.Int J Radiat Oncol Biol Phys, vol. 98, no. 2, June 2017, pp. 473–80. Pubmed, doi:10.1016/j.ijrobp.2017.02.089.
Journal cover image

Published In

Int J Radiat Oncol Biol Phys

DOI

EISSN

1879-355X

Publication Date

June 1, 2017

Volume

98

Issue

2

Start / End Page

473 / 480

Location

United States

Related Subject Headings

  • Tumor Burden
  • Seminal Vesicles
  • Radiotherapy Planning, Computer-Assisted
  • Radiosurgery
  • Prostatic Neoplasms
  • Prostate
  • Oncology & Carcinogenesis
  • Movement
  • Motion
  • Male