Standardization of dosimetry chart checks.

This paper reports on a standardized report form that can be used to analyze dose error rates from radiation therapy. An error classification scheme of Types 1 to 5 was developed to indicate increasing severity of errors. Type 1 (charting errors) and Type 3 (daily dose errors) were the most prominent types. Dosimetry errors were reduced by using the results of the reports to correct operating procedures. Type 1 error rates decreased from 17% initially to an average of 3.9%. An average error rate of 1.7% for Type 3 dose errors was found to be consistent with normal operation. Use of the report form is useful in documenting and correcting errors and as a reporting record for use in a quality assurance program.

Optimization of xeroradiographic exposures.

Xeroradiographs were exposed over a range of mAs and kVp in the mammographic energy range. At each kVp, the technique yielding the widest halo also produced the greatest detectability of small aluminum specks in mammographic phantoms. As the kVp increased, the maximum halo width and number of visible specks decreased. At all kVps, the techniques yielding the widest halo furnished almost constant energy deposition in the selenium plate. This constant plate dose was correlated to patient exposure at the entrance of the breast, and the relationships between patient entrance exposure, kVp, and minumum detectable speck size were determined.