Quality control of custom block making in radiation therapy.

Custom blocks are the most commonly used field shaping device in radiotherapy. They offer many advantages in daily clinical use. However, as with all accessories used for patient treatments, care must be taken with their use. As such, a quality control program to check block cutting accuracy is recommended as a routine part of their clinical use. We have developed a three step method for checking custom blocks before they are used for patient treatment. These steps include: a static light check, a parallel opposed film check, and a block check involving the patient. By completing these three steps, we feel that we have improved the overall accuracy of our custom block making system which has resulted in more accurate treatments for our patients.