Role of point A in the era of computerized dosimetry

Treatment prescriptions based on milligram-hours and point A doses were examined in light of the recommended dose and volume specification for intracavitary therapy proposed by the International Commission on Radiation Units and Measurements (ICRU). Because neither point A doses nor milligram-hours are to be included in dose reporting, it is necessary to translate the vast empirical experience with prescriptions based on these parameters into the ICRU schema. A total of 90 Fletcher-Suit radium applications were analyzed to explore relationships between point A doses, milligram-hours, and the ICRU guidelines. It was demonstrated that some definitions of point A can have essentially no utility within any dosimetric system, while others can lead to treatment prescriptions with some degree of correspondence to ICRU recommendations. Older dosimetric concepts must be retained while newer ones are being developed.