Single and Multibeam Dose Distribution for Treatment Planning of Cancer

Abstract

The development of radiotherapy techniques has aimed at the goal of irradiating a small localised region by sparing the surrounding healthy tissues. Therefore the success of radiosurgery is critically based on the accurate information of the distribution of the absorbed dose. Treatment planning for conventional radiations is based on the assumption that the effect of a combination of doses at any location in the treatment field in a multibeam plan will be equivalent to that of a single dose made up of the total sum of the doses delivered to that location.Treatment planning data of 80 patients treated on Cobalt-60 unit for the treatment of cancer lying in different organs was analyzed. The dose distribution chart was evaluated for the target and risk organs. The results of the treatment planning with single field, for tumor at Pelvis, show the average prescribed dose of 200 cGy was delivered to the target volume with variation of ±11.6% (The healthy organs like Scrum and Rectum also received a dose of 124 cGy and 95.5 cGy respectively). The result with three fields, show the average prescribed dose of 200 cGy was delivered to the target volume with variation of ±6.2%. The healthy organs like Scrum and Rectum received a dose of 57.1 cGy and 37.4 cGy respectively which shows a reduction of about 54%. The results of other organs also show the like trend. The investigation show that the use of multibeam treatment planning in radiation therapy reduces the risk of unwanted absorbed dose in healthy tissues and increases the accuracy of delivering the prescribed dose to the tumour volume. Multibeam treatment also provide a delivery of more dose to the target volume, especially surrounded by other healthy organs as compare to the single beam radiation therapy.