Method of dosage calculation for linear radium sources.

Abstract

As a routine procedure in intracavitary or interstitial radium treatment, every patient is radiographed in order to visualize the distribution of sources after implantation. Frequently it is discovered that the planned arrangement of sources differs from what is accomplished in the operating room. Sources are found to be well spaced in one region and far apart in another, so that, although one area of tumor is properly dosed, another is inadequately dosed. Sometimes the arrangement is found to be such that there are “hot spots” in regions which tolerate radiation poorly. Of particular interest are cases of cervical cancer under treatment by an intracavitary technic, since sources in the uterus and vagina can be so situated as to deliver a harmful dose to the rectum or bladder. Meredith (1) has considered this problem in detail. Calculation of the amount of radiation reaching such points of interest is often neglected, the dose being expressed simply as the number of milligram-hours. The range is from 5,00...