Skip to main content

Comparison of online IGRT techniques for prostate IMRT treatment: adaptive vs repositioning correction.

Publication ,  Journal Article
Thongphiew, D; Wu, QJ; Lee, WR; Chankong, V; Yoo, S; McMahon, R; Yin, F-F
Published in: Med Phys
May 2009

This study compares three online image guidance techniques (IGRT) for prostate IMRT treatment: bony-anatomy matching, soft-tissue matching, and online replanning. Six prostate IMRT patients were studied. Five daily CBCT scans from the first week were acquired for each patient to provide representative "snapshots" of anatomical variations during the course of treatment. Initial IMRT plans were designed for each patient with seven coplanar 15 MV beams on a Eclipse treatment planning system. Two plans were created, one with a PTV margin of 10 mm and another with a 5 mm PTV margin. Based on these plans, the delivered dose distributions to each CBCT anatomy was evaluated to compare bony-anatomy matching, soft-tissue matching, and online replanning. Matching based on bony anatomy was evaluated using the 10 mm PTV margin ("bone10"). Soft-tissue matching was evaluated using both the 10 mm ("soft10") and 5 mm ("soft5") PTV margins. Online reoptimization was evaluated using the 5 mm PTV margin ("adapt"). The replanning process utilized the original dose distribution as the basis and linear goal programming techniques for reoptimization. The reoptimized plans were finished in less than 2 min for all cases. Using each IGRT technique, the delivered dose distribution was evaluated on all 30 CBCT scans (6 patients x 5 CBCT/patient). The mean minimum dose (in percentage of prescription dose) to the CTV over five treatment fractions were in the ranges of 99%-100% (SD = 0.1%-0.8%), 65%-98% (SD = 0.4%-19.5%), 87%-99% (SD = 0.7%-23.3%), and 95%-99% (SD = 0.4%-10.4%) for the adapt, bone10, soft5, and soft10 techniques, respectively. Compared to patient position correction techniques, the online reoptimization technique also showed improvement in OAR sparing when organ motion/deformations were large. For bladder, the adapt technique had the best (minimum) D90, D50, and D30 values for 24, 17, and 15 fractions out of 30 total fractions, while it also had the best D90, D50, and D30 values for the rectum for 25, 16, and 19 fractions, respectively. For cases where the adapt plans did not score the best for OAR sparing, the gains of the OAR sparing in the repositioning-based plans were accompanied by an underdosage in the target volume. To further evaluate the fast online replanning technique, a gold-standard plan ("new" plan) was generated for each CBCT anatomy on the Eclipse treatment planning system. The OAR sparing from the online replanning technique was compared to the new plan. The differences in D90, D50, and D30 of the OARs between the adapt and the new plans were less than 5% in 3 patients and were between 5% and 10% for the remaining three. In summary, all IGRT techniques could be sufficient to correct simple geometrical variations. However, when a high degree of deformation or differential organ position displacement occurs, the online reoptimization technique is feasible with less than 2 min optimization time and provides improvements in both CTV coverage and OAR sparing over the position correction techniques. For these cases, the reoptimization technique can be a highly valuable online IGRT tool to correct daily treatment uncertainties, especially when hypofractionation scheme is applied and daily correction, rather than averaging over many fractions, is required to match the original plan.

Duke Scholars

Altmetric Attention Stats
Dimensions Citation Stats

Published In

Med Phys

DOI

ISSN

0094-2405

Publication Date

May 2009

Volume

36

Issue

5

Start / End Page

1651 / 1662

Location

United States

Related Subject Headings

  • Treatment Outcome
  • Tomography, X-Ray Computed
  • Sensitivity and Specificity
  • Reproducibility of Results
  • Radiotherapy, Computer-Assisted
  • Radiographic Image Interpretation, Computer-Assisted
  • Prostatic Neoplasms
  • Nuclear Medicine & Medical Imaging
  • Male
  • Humans
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Thongphiew, D., Wu, Q. J., Lee, W. R., Chankong, V., Yoo, S., McMahon, R., & Yin, F.-F. (2009). Comparison of online IGRT techniques for prostate IMRT treatment: adaptive vs repositioning correction. Med Phys, 36(5), 1651–1662. https://doi.org/10.1118/1.3095767
Thongphiew, Danthai, Q Jackie Wu, W Robert Lee, Vira Chankong, Sua Yoo, Ryan McMahon, and Fang-Fang Yin. “Comparison of online IGRT techniques for prostate IMRT treatment: adaptive vs repositioning correction.Med Phys 36, no. 5 (May 2009): 1651–62. https://doi.org/10.1118/1.3095767.
Thongphiew D, Wu QJ, Lee WR, Chankong V, Yoo S, McMahon R, et al. Comparison of online IGRT techniques for prostate IMRT treatment: adaptive vs repositioning correction. Med Phys. 2009 May;36(5):1651–62.
Thongphiew, Danthai, et al. “Comparison of online IGRT techniques for prostate IMRT treatment: adaptive vs repositioning correction.Med Phys, vol. 36, no. 5, May 2009, pp. 1651–62. Pubmed, doi:10.1118/1.3095767.
Thongphiew D, Wu QJ, Lee WR, Chankong V, Yoo S, McMahon R, Yin F-F. Comparison of online IGRT techniques for prostate IMRT treatment: adaptive vs repositioning correction. Med Phys. 2009 May;36(5):1651–1662.

Published In

Med Phys

DOI

ISSN

0094-2405

Publication Date

May 2009

Volume

36

Issue

5

Start / End Page

1651 / 1662

Location

United States

Related Subject Headings

  • Treatment Outcome
  • Tomography, X-Ray Computed
  • Sensitivity and Specificity
  • Reproducibility of Results
  • Radiotherapy, Computer-Assisted
  • Radiographic Image Interpretation, Computer-Assisted
  • Prostatic Neoplasms
  • Nuclear Medicine & Medical Imaging
  • Male
  • Humans