Benchmarking Dosimetric Quality Assessment of Prostate Intensity-Modulated Radiotherapy

• Published in: International journal of radiation oncology, biology, physics Vol. 82; no. 2; pp. 998 - 1005
• Main Authors: Senthi, Sashendra, M.B.Ch.B, Gill, Suki S., F.R.C.R, Haworth, Annette, Ph.D, Kron, Tomas, Ph.D, Cramb, Jim, M.Sc, Rolfo, Aldo, Dip.Appl.Sci., M.B.A, Thomas, Jessica, M.Sc, Duchesne, Gillian M., M.D., F.R.A.N.Z.C.R, Hamilton, Christopher H., M.D., F.R.A.N.Z.C.R, Joon, Daryl Lim, F.R.A.N.Z.C.R, Bowden, Patrick, F.R.A.N.Z.C.R, Foroudi, Farshad, F.R.A.N.Z.C.R
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01-02-2012; Elsevier
• Subjects: Aged; Aged, 80 and over; Androgen Antagonists - therapeutic use; ANDROGENS; Applied radiobiology (equipment, dosimetry...); Benchmarking - methods; Benchmarking - standards; BENCHMARKS; Biological and medical sciences; Biological effects of radiation; Confidence Intervals; DOSIMETRY; Fundamental and applied biological sciences. Psychology; HAZARDS; Hematology, Oncology and Palliative Medicine; Humans; IMRT; Intensity-modulated radiotherapy; Male; MEN; Middle Aged; MULTIVARIATE ANALYSIS; Neoplasm Staging; NEOPLASMS; Organs at Risk; PATIENTS; PLANNING; PROSTATE; Prostatic Neoplasms - drug therapy; Prostatic Neoplasms - pathology; Prostatic Neoplasms - radiotherapy; QUALITY ASSURANCE; RADIATION DOSES; Radiology; RADIOLOGY AND NUCLEAR MEDICINE; RADIOTHERAPY; Radiotherapy Dosage; Radiotherapy, Intensity-Modulated - methods; Radiotherapy, Intensity-Modulated - standards; Regression Analysis; Retrospective Studies; Target coverage; Tissues, organs and organisms biophysics; Tumor Burden; Victoria; Victoria; Quality assurance; Intensity-modulated radiotherapy; Dosimetry; IMRT; Target coverage; Prostate; Intensity modulated radiotherapy; Cancerology; Treatment; Targeting; Quality
• ISSN: 0360-3016; 1879-355X
• DOI: 10.1016/j.ijrobp.2010.12.016

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 (V95% and V100% , 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 V95% , PTV sigma index, and conformity number. The mean PTV V95% was 92.5% (95% confidence interval, 91.3–93.7%). The mean PTV sigma index 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 V95% 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.