The factors that effects the choice of treatment machine for external pelvic radiotherapy and comparison of the side-effects

Abstract

The aim of the radiotherapy is to eliminate the malign cells by using ionizing radiotherapy. Radiotherapy is being used rather frequently for the treatment of pelvic tumors as a primary modality or with the combination of the others. This study is designed in Ondokuz Mayis University School of Medicine Radiation Oncology Department between January 2006 and December 2007. Ninety-five patients were treated with pelvic external radiotherapy in this period. There were two different treatment machines which have differences for the acute radiotherapy toxicity, working principles and beam characteristics. These differences and also, the factors that might be associated with radiotherapy toxicity are analyzed. Of the patients 43,2% were male, and 56,8% were female and the mean age was 60,71 + 13,1. When examined the primary diagnosis, external pelvic radiotherapy treatment was given for rectal cancer (32,6%) most frequently. The treatment machine was Cobalt 60 teletherapy machine in 43,2% patients and Linear accelerator with energy of 18 MV in 56,8% patient. The mean front to back radius of the patients was 10,63±1,43 cm, the mean overall treatment radiotherapy dose was 5481,68±817,24 cGy. Although the overall treatment dose was higher in linear accelerator treatment group the difference was not significant (p=0,053). The curative treatments were made with linear accelerator (p=0,04), where more palliative treatments were made with Cobalt 60 machine. More complex treatments (multiple fields) were used in Linear accelerator treatments (p=0,001). The front to back radius of the patients in linear accelerator treatment group was higher (p=0,001). When compared for the side-effects; the patients who were treated with Cobalt 60 has more gastrointestinal side-effects at the first treatment week (p=0,02) and skin side-effects at the third treatment week (p=0,04). As a conclusion; for the external radiotherapy of pelvic tumors linear accelerator is more suitable with less side-effect.