Assaying 192Ir line sources using a standard length well chamber.
The strength of intravascular 192Ir sources is typically measured by the manufacturer before shipment, and treatment planning is based on that assay. However, in-house verification of source strength is required at some institutions by state law or internal policy, is recommended by the AAPM TG 60 report on intravascular brachytherapy, and is considered a necessity by many medical physicists. To accommodate the long sources used in intravascular therapy, special well chambers with extended regions of constant response have been designed. To allow assays using a widely available standard well chamber, we have measured its position dependent sensitivity and derived from it a table of correction factors that account for the extended length of intravascular sources. An experimental verification shows that application of these correction factors yields assays with sufficient accuracy for routine quality assurance tests.
Brezovich
Ivan A
IA
Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, Alabama 35233, USA. ibrezovich@uabmc.edu
Popple
Richard A
RA
Duan
Jun
J
Shen
Sui
S
Pareek
Prem N
PN
D001918:Brachytherapy / Q000295:instrumentation / Q000592:standards*; D002138:Calibration / Q000592:standards*; D004867:Equipment Design; D019544:Equipment Failure Analysis / Q000295:instrumentation / Q000379:methods / Q000592:standards*; D006801:Humans; D007496:Iridium Radioisotopes / Q000592:standards*; D018499:Linear Energy Transfer; D011786:Quality Control; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods / Q000592:standards*; D011879:Radiotherapy Dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014481:United States; D014652:Vascular Diseases / Q000532:radiotherapy
D007496:Iridium Radioisotopes