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Dosimetric effect of intrafraction motion and residual setup error for hypofractionated prostate intensity-modulated radiotherapy with online cone beam computed tomography image guidance.

Publication ,  Journal Article
Adamson, J; Wu, Q; Yan, D
Published in: Int J Radiat Oncol Biol Phys
June 1, 2011

PURPOSE: To quantify the dosimetric effect and margins required to account for prostate intrafractional translation and residual setup error in a cone beam computed tomography (CBCT)-guided hypofractionated radiotherapy protocol. METHODS AND MATERIALS: Prostate position after online correction was measured during dose delivery using simultaneous kV fluoroscopy and posttreatment CBCT in 572 fractions to 30 patients. We reconstructed the dose distribution to the clinical tumor volume (CTV) using a convolution of the static dose with a probability density function (PDF) based on the kV fluoroscopy, and we calculated the minimum dose received by 99% of the CTV (D(99)). We compared reconstructed doses when the convolution was performed per beam, per patient, and when the PDF was created using posttreatment CBCT. We determined the minimum axis-specific margins to limit CTV D(99) reduction to 1%. RESULTS: For 3-mm margins, D(99) reduction was ≤5% for 29/30 patients. Using post-CBCT rather than localizations at treatment delivery exaggerated dosimetric effects by ~47%, while there was no such bias between the dose convolved with a beam-specific and patient-specific PDF. After eight fractions, final cumulative D(99) could be predicted with a root mean square error of <1%. For 90% of patients, the required margins were ≤2, 4, and 3 mm, with 70%, 40%, and 33% of patients requiring no right-left (RL), anteroposterior (AP), and superoinferior margins, respectively. CONCLUSIONS: For protocols with CBCT guidance, RL, AP, and SI margins of 2, 4, and 3 mm are sufficient to account for translational errors; however, the large variation in patient-specific margins suggests that adaptive management may be beneficial.

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Published In

Int J Radiat Oncol Biol Phys

DOI

EISSN

1879-355X

Publication Date

June 1, 2011

Volume

80

Issue

2

Start / End Page

453 / 461

Location

United States

Related Subject Headings

  • Tumor Burden
  • Radiotherapy, Intensity-Modulated
  • Radiotherapy Planning, Computer-Assisted
  • Prostatic Neoplasms
  • Prostate
  • Patient Positioning
  • Oncology & Carcinogenesis
  • Movement
  • Male
  • Humans
 

Citation

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ICMJE
MLA
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Adamson, J., Wu, Q., & Yan, D. (2011). Dosimetric effect of intrafraction motion and residual setup error for hypofractionated prostate intensity-modulated radiotherapy with online cone beam computed tomography image guidance. Int J Radiat Oncol Biol Phys, 80(2), 453–461. https://doi.org/10.1016/j.ijrobp.2010.02.033
Adamson, Justus, Qiuwen Wu, and Di Yan. “Dosimetric effect of intrafraction motion and residual setup error for hypofractionated prostate intensity-modulated radiotherapy with online cone beam computed tomography image guidance.Int J Radiat Oncol Biol Phys 80, no. 2 (June 1, 2011): 453–61. https://doi.org/10.1016/j.ijrobp.2010.02.033.
Adamson, Justus, et al. “Dosimetric effect of intrafraction motion and residual setup error for hypofractionated prostate intensity-modulated radiotherapy with online cone beam computed tomography image guidance.Int J Radiat Oncol Biol Phys, vol. 80, no. 2, June 2011, pp. 453–61. Pubmed, doi:10.1016/j.ijrobp.2010.02.033.
Journal cover image

Published In

Int J Radiat Oncol Biol Phys

DOI

EISSN

1879-355X

Publication Date

June 1, 2011

Volume

80

Issue

2

Start / End Page

453 / 461

Location

United States

Related Subject Headings

  • Tumor Burden
  • Radiotherapy, Intensity-Modulated
  • Radiotherapy Planning, Computer-Assisted
  • Prostatic Neoplasms
  • Prostate
  • Patient Positioning
  • Oncology & Carcinogenesis
  • Movement
  • Male
  • Humans