Online adaptive replanning method for prostate radiotherapy

Ergun E. Ahunbay, Cheng Peng, Shannon Holmes, Andrew Godley, Colleen Lawton, X. Allen Li

Research output: Contribution to journalArticlepeer-review

78 Scopus citations


Purpose: To report the application of an adaptive replanning technique for prostate cancer radiotherapy (RT), consisting of two steps: (1) segment aperture morphing (SAM), and (2) segment weight optimization (SWO), to account for interfraction variations. Methods and Materials: The new "SAM+SWO" scheme was retroactively applied to the daily CT images acquired for 10 prostate cancer patients on a linear accelerator and CT-on-Rails combination during the course of RT. Doses generated by the SAM+SWO scheme based on the daily CT images were compared with doses generated after patient repositioning using the current planning target volume (PTV) margin (5 mm, 3 mm toward rectum) and a reduced margin (2 mm), along with full reoptimization scans based on the daily CT images to evaluate dosimetry benefits. Results: For all cases studied, the online replanning method provided significantly better target coverage when compared with repositioning with reduced PTV (13% increase in minimum prostate dose) and improved organ sparing when compared with repositioning with regular PTV (13% decrease in the generalized equivalent uniform dose of rectum). The time required to complete the online replanning process was 6 ± 2 minutes. Conclusion: The proposed online replanning method can be used to account for interfraction variations for prostate RT with a practically acceptable time frame (5-10 min) and with significant dosimetric benefits. On the basis of this study, the developed online replanning scheme is being implemented in the clinic for prostate RT.

Original languageEnglish (US)
Pages (from-to)1561-1572
Number of pages12
JournalInternational Journal of Radiation Oncology Biology Physics
Issue number5
StatePublished - Aug 1 2010
Externally publishedYes


  • Adaptive radiotherapy
  • Image-guided radiotherapy
  • Online replanning
  • Prostate cancer

ASJC Scopus subject areas

  • Radiation
  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research


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