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Title: Benchmarking Dosimetric Quality Assessment of Prostate Intensity-Modulated Radiotherapy

Purpose: To benchmark the dosimetric quality assessment of prostate intensity-modulated radiotherapy and determine whether the quality is influenced by disease or treatment factors. Patients and Methods: We retrospectively analyzed the data from 155 consecutive men treated radically for prostate cancer using intensity-modulated radiotherapy to 78 Gy between January 2007 and March 2009 across six radiotherapy treatment centers. The plan quality was determined by the measures of coverage, homogeneity, and conformity. Tumor coverage was measured using the planning target volume (PTV) receiving 95% and 100% of the prescribed dose (V{sub 95%} and V{sub 100%}, respectively) and the clinical target volume (CTV) receiving 95% and 100% of the prescribed dose. Homogeneity was measured using the sigma index of the PTV and CTV. Conformity was measured using the lesion coverage factor, healthy tissue conformity index, and the conformity number. Multivariate regression models were created to determine the relationship between these and T stage, risk status, androgen deprivation therapy use, treatment center, planning system, and treatment date. Results: The largest discriminatory measurements of coverage, homogeneity, and conformity were the PTV V{sub 95%}, PTV sigma index, and conformity number. The mean PTV V{sub 95%} was 92.5% (95% confidence interval, 91.3-93.7%). The mean PTV sigma indexmore » was 2.10 Gy (95% confidence interval, 1.90-2.20). The mean conformity number was 0.78 (95% confidence interval, 0.76-0.79). The treatment center independently influenced the coverage, homogeneity, and conformity (all p < .0001). The planning system independently influenced homogeneity (p = .038) and conformity (p = .021). The treatment date independently influenced the PTV V{sub 95%} only, with it being better at the start (p = .013). Risk status, T stage, and the use of androgen deprivation therapy did not influence any aspect of plan quality. Conclusion: Our study has benchmarked measures of coverage, homogeneity, and conformity for the treatment of prostate cancer using IMRT. The differences seen between centers and planning systems and the coverage deterioration over time highlight the need for every center to determine their own benchmarks and apply clinical vigilance with respect to maintaining these through quality assurance.« less
Authors:
 [1] ;  [1] ; ; ;  [2] ;  [3] ;  [4] ;  [1] ; ;  [5] ;  [6] ;  [1]
  1. Division of Radiation Oncology, Peter MacCallum Cancer Center, East Melbourne, VIC (Australia)
  2. Department of Physical Sciences, Peter MacCallum Cancer Center, East Melbourne, VIC (Australia)
  3. Radiation Therapy Services, Peter MacCallum Cancer Center, East Melbourne, VIC (Australia)
  4. Biostatistics and Clinical Trials, Peter MacCallum Cancer Center, East Melbourne, VIC (Australia)
  5. Radiation Oncology Department, Austin Repatriation Hospital, Heidelberg, VIC (Australia)
  6. Radiation Oncology Department, Tattersall's Cancer Center, East Melbourne, VIC (Australia)
Publication Date:
OSTI Identifier:
22056081
Resource Type:
Journal Article
Resource Relation:
Journal Name: International Journal of Radiation Oncology, Biology and Physics; Journal Volume: 82; Journal Issue: 2; Other Information: Copyright (c) 2012 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; ANDROGENS; BENCHMARKS; DOSIMETRY; HAZARDS; MEN; MULTIVARIATE ANALYSIS; NEOPLASMS; PATIENTS; PLANNING; PROSTATE; QUALITY ASSURANCE; RADIATION DOSES; RADIOTHERAPY