Assessment Of Dose Variation To Critical Points In Low Dose Rate Intracavitary Brachytherapy Of Cervical Cancer At Komfo Anokye Teaching Hospital

Abstract

For LDR brachytherapy, the time taken to deliver the dose to a patient is very long which makes the patient be on the machine for a very long period of time. Due to this long treatment time, soaking of vaginal packing and patient movement can change the applicators position. The aim of this work is to assess the dose variation to point ‘A’ and point ‘B’ as well as critical organs (i.e. bladder and rectum) for low dose rate (LDR) brachytherapy at Komfo Anokye Teaching Hospital. Forty (40) patients with invasive cervical cancer were treated with LDR brachytherapy with 30 – 35Gy prescription to point ‘A’. Two pairs of orthogonal X-ray images were taken: one prior to treatment and the other after treatment. Pre- and post- treatment doses were calculated and analyzed to determine the variation in the doses to points ‘A’ and ‘B’, as well as, the critical organs. The disparity in dose to point ‘A’ was found to be 1.16% which is very laudable as compared to other studies that established dose variations of 2, 35, 8 and 20%. Variation in dose at point B in this work was 0.75%. In this study, average variations of 2.32 and 0.30% were found for the bladder and rectum, respectively. For quality assurance purposes the variation found between prescribed and deposited dose was 2.11%. The geometric variations between the Intracavitary Brachytherapy Treatment (ICBT) applicators and the critical organs vary during the treatment procedure and thus result in dose alterations. Since the variation is within the recommended standard levels, it can be concluded that, the practice at KATH meets the international standard.