Prostate intrafraction motion assessed by simultaneous kV fluoroscopy at MV delivery II: adaptive strategies.

Journal Article (Journal Article)

PURPOSE: To investigate potential benefits of adaptive strategies for managing prostate intrafractional uncertainties when interfraction motion is corrected online. METHODS AND MATERIALS: Prostate intrafraction motion was measured using kV fluoroscopy during MV delivery for 571 fractions from 30 hypofractionated radiotherapy patients. We evaluated trending over treatment course using analysis of variance statistics, and we evaluated the ability to correct patient-specific systematic error and apply patient-specific statistical margins after 2 to 15 fractions to compensate 90% of motion. We also evaluated the ability to classify patients into small- and large-motion subgroups based on the first 2 to 20 fractions using discriminant analysis. RESULTS: No time trend was observed over treatment course, and intrafraction motion was patient specific (p < 0.0001). Systematic error in the first week correlated well with that in subsequent weeks, with correlation coefficients of 0.53, 0.50, and 0.41 in right-left (RL), anterior-posterior (AP), and superior-inferior (SI), respectively. After 5 fractions, the adaptive strategy resulted in average margin reductions of 0.3, 0.7, and 0.7 mm in RL, AP, and SI, respectively, with margins ranging from 1 to 3.2 mm in RL, 2 to 7.0 mm in AP, and 2 to 6.6 mm in SI. By contrast, population margins to include the same percentage of motion were 1.7, 4.0, and 4.1 mm. After 2 and 5 fractions, patients were classified into small- and large-motion groups with ~77% and ~83% accuracy. CONCLUSIONS: Adaptive strategies are feasible and beneficial for intrafraction motion management in prostate cancer online image guidance. Patients may be classified into large- and small-motion groups in early fractions using discriminant analysis.

Full Text

Duke Authors

Cited Authors

  • Adamson, J; Wu, Q

Published Date

  • December 1, 2010

Published In

Volume / Issue

  • 78 / 5

Start / End Page

  • 1323 - 1330

PubMed ID

  • 20584578

Pubmed Central ID

  • PMC2948079

Electronic International Standard Serial Number (EISSN)

  • 1879-355X

Digital Object Identifier (DOI)

  • 10.1016/j.ijrobp.2009.09.079


  • eng

Conference Location

  • United States