Dosage accuracy in clinical radiation therapy. I. Clinical dosimetric aspects

Abstract

The objective in radiation therapy treatment is to deliver as accurately as possible a cancercidal dose of radiation to a specified volume of tumour tissue while sparing the surrounding normal tissue. The overall error in dosage delivered should be within +or-5% when using any specified treatment plan. The authors present the result of a study of the errors usually seen in the treatment of patients with radiation and a discussion the method of minimizing these errors. At present, in most radiotherapy departments, the physical dosimetry is being very well performed by the physicists in regard to both precision and accuracy. There is no information concerning whether clinical dosimetry such as the daily setting up of the patient, the treatment time for the daily tumour dose, etc has the desired degree of precision and accuracy. A systematic analysis of 1200 treatment cards of patients treated since 1970 shows the calculated treatment time was in error by 5% or more in 10% of the cases.