Evaluation of Skin Dose In Nasopharyngeal Cancer Irradiation

Abstract

Nasopharyngeal carcinoma is a common disease in Sudan3 % (2000-2007), and the treatment is external radiation therapy for radical treatment. The treatment is given via of two large lateral opposed field's covers the area above the pituitary fossa to include the base of the skull to the clavicle by a dose equal 5000 cGy in 25 fractions , 5 fractions per week.The radiation passes through the skin which might lead to radiation complication(erythema).

This study conducted at the Radiation and Isotopic Center of Khartoum (RICK) in the period from August 2007 to May 2008. The main objective of this study was to evaluate the dose received by the skin.

The radiation dose was measured during the treatment course by using (TLD-GR200) to measure the skin dose for patients treated under the Co-60 machine, as well as the Treatment Planning System (TPS). The result showed that the mean dose that received by the skin at the center of the field that measured by TLD was 2978.4±300.8 and the skin dose that calculate by TPS was 3047.3±197, the result also showed that the dose in the lower of the field was higher than that of the upper field region because of this region thinner than the other parts.

The tolerance of normal tissue (of the skin to conventional fractionated irradiation is approximately 3500 cGy) is of great practical importance to the