Dose specification and quality assurance of radiation therapy oncology group protocol 95-17; a cooperative group study of iridium-192 breast implants as sole therapy.
OBJECTIVE
The Radiation Therapy Oncology Group (RTOG) protocol 95-17 was a Phase I/II trial to evaluate multicatheter brachytherapy as the sole method of adjuvant breast radiotherapy for Stage I/II breast carcinoma after breast-conserving surgery. Low- or high-dose-rate sources were allowed. Dose prescription and treatment evaluation were based on recommendations in the International Commission on Radiation Units and Measurements (ICRU), Report 58 and included the parameters mean central dose (MCD), average peripheral dose, dose homogeneity index (DHI), and the dimensions of the low- and high-dose regions.


METHODS
Three levels of quality assurance were implemented: (1) credentialing of institutions was required before entering patients into the study; (2) rapid review of each treatment plan was conducted before treatment; and (3) retrospective review was performed by the Radiological Physics Center in conjunction with the study chairman and RTOG dosimetry staff.


RESULTS
Credentialing focused on the accuracy of dose calculation algorithm and compliance with protocol guidelines. Rapid review was designed to identify and correct deviations from the protocol before treatment. The retrospective review involved recalculation of dosimetry parameters and review of dose distributions to evaluate the treatment. Specifying both central and peripheral doses resulted in uniform dose distributions, with a mean dose homogeneity index of 0.83 +/- 0.06.


CONCLUSIONS
Vigorous quality assurance resulted in a high-quality study with few deviations; only 4 of 100 patients were judged as representing minor variations from protocol, and no patient was judged as representing major deviation. This study should be considered a model for quality assurance of future trials.
Radiological Physics Center, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA. gibbott@mdanderson.org
Geoffrey S
GS
Ibbott
W F
WF
Hanson
Elizabeth
E
O'Meara
Robert R
RR
Kuske
Douglas
D
Arthur
Rachel
R
Rabinovitch
Julia
J
White
Raymond M
RM
Wilenzick
Irene
I
Harris
Ramesh C
RC
Tailor
D019985:Benchmarking; D001918:Brachytherapy / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D001943:Breast Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D003406:Credentialing; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007496:Iridium Radioisotopes / Q000627:therapeutic use*; D015412:Mastectomy, Segmental; D011879:Radiotherapy Dosage; D018714:Radiotherapy, Adjuvant / Q000379:methods; D015203:Reproducibility of Results; D012189:Retrospective Studies
D007496:Iridium Radioisotopes