Determination of Relative Biological Effectiveness (RBE) of Soft X Rays

Publisher Website
Google Scholar
Abstract
Differences in clinical results reported with the use of 125I encapsulated implants compared to those with 198Au, 222-Rn, and 192Ir prompted a study of the RBE, relative to 60Co .gamma.-radiation, of X-rays simulating the spectral distribution of radiation from encapsulated 125I. The parameter used for RBE determination was the killing of surface attached log phase HeLa-S3 [human cervical cancer] cells. The RBE was determined at dose rates varying from 15-130 rads/min which are .apprx. 90-500 times greater than those employed in therapy with interstitial 125I implants. It was .apprx. 1.4 when measured as a ratio of D0 and 1.3 as determined on the basis of the ratio of doses for 10% survival (dose rates of 15 and 30 rads/min). The RBE values were dose rate dependent, increasing linearly from 130 to 30 rads/min and possibly leveling off below this point.

This publication has 1 reference indexed in Scilit: