State of Dose Prescription and Compliance to International Standard (ICRU-83) in Intensity Modulated Radiation Therapy among Academic Institutions

Publication date: Available online 13 November 2016
Source:Practical Radiation Oncology
Author(s): Indra J Das, Aaron Andersen, Zhe (Jay) Chen, Andrea Dimofte, Eli Glatstein, Jeremy Hoisak, Long Huang, Mark P. Langer, Choonik Lee, Matthew Pacella, Richard A. Popple, Roger Rice, Jennifer Smilowitz, Patricia Sponseller, Timothy Zhu
Purpose/Objective(s)To evaluate dose prescription and recording compliance to international standard (ICRU-83) in IMRT treated patients among academic institutions.Materials/MethodsTen institutions participated in this study to collect IMRT data to evaluate compliance to ICRU-83. Under institutional review board (IRB) clearance, 5094 patient data including treatment site, technique, planner, physician, prescribed dose, target volume, monitor units, planning system and dose calculation algorithm were collected anonymously. The dose-volume histogram (DVH) of each patient, as well as dose points, D100, D98, D95, D50, D2 were collected and sent to a central location for analysis. Homogeneity index (HI) as a measure of the steepness of target which is a measure of the shape of the DVH was calculated for every patient and analyzed.ResultsIn general, ICRU recommendations for naming the target, reporting dose prescription, and achieving desired levels of dose to target were relatively poor. The nomenclature for the target in the dose prescription had large variations, having every permutation of name and number contrary to ICRU recommendations. There was statistically significant variability in D95, D50 and HI among institutions, tumor site and technique with p values <0.01. Nearly 95% of patients had D50 higher than 100% (103.5±6.9) of prescribed dose and varied among institutions. On the other hand, D95 was close to 100% (97.1±9.4) of prescribed dose. Liver and lung sites had a higher D50 compared to other sites. Pelvic sites had a lower variability indicated by HI (0.13±1.21). Variability in D50 is 101.2±8.5, 103.4±6.8, 103.4±8.2 and 109.5±11.5 for IMRT, Tomotherapy, VMAT and SBRT with IMRT, respectively.ConclusionNearly 95% of patient treatments deviated from the ICRU-83 recommended D50 prescription dose delivery. This variability is significant (p<0.01) in terms of treatment site, technique and institution. To reduce dosimetric and associated radiation outcome variability, dose prescription in every clinical trial should be unified with international guidelines.



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