Dose rate definition with microSelectron-HDR and Selectron-MDR in brachytherapy for carcinoma of the cervix.
BACKGROUND
Reproducibility of dose rate at point A is the main characteristic of Manchester system for dose prescription for cancer cervix brachytherapy. Here, we investigated dose rate variations at point A in the application of Selectron-MDR and microSelectron-HDR.


METHODS
All applications were compared for their physical aspects (loading and geometry). Two points A(rev) and A(or) (revised and original definitions) were checked for dose rate variations. Here we proposed a tool "dose rate radium equivalent" (Ra-eq.DR) to cancel the effect of source decay on the variation of dose rate values.


RESULTS
Both techniques showed very similar geometry, tandem-ovoid loading ratio, and Ra-eq.DR at A(rev) and A(or). However, the best reproducibility of dose rate was achieved with A(or). Also, time variable-dose rate definition affected the difference between the 2 treatments modalities.


CONCLUSIONS
Clear definition of both the point of dose prescription and the time variable used for dose rate calculation are important for brachytherapy for cancer of the cervix.
Department of Radiation Oncology, Osaka University Medical School, Suita, Japan.
M M
MM
el-Baradie
N
N
Fournier-Bidoz
T
T
Inoue
T
T
Inoue
H
H
Yamazaki
D001918:Brachytherapy / Q000379:methods*; D005260:Female; D006801:Humans; D011879:Radiotherapy Dosage; D015203:Reproducibility of Results; D002583:Uterine Cervical Neoplasms / Q000532:radiotherapy*