Dosimetric analysis of Co-60 source based high dose rate (HDR) brachytherapy: A case series of ten patients with carcinoma of the uterine cervix

Abstract

Aim

To analyse the dosimetric parameters of Co-60 based high dose rate (HDR) brachytherapy plans for patients of carcinoma uterine cervix.

Background

Co-60 high dose rate (HDR) brachytherapy unit has been introduced in past few years and is gaining importance owing to its long half life, economical benefits and comparable clinical outcome compared to Ir-192 HDR brachytherapy.

Materials and methods

A study was conducted on ten patients with locally advanced carcinoma of the uterine cervix (Ca Cx). Computed tomography (CT) images were taken after three channel applicator insertions. The planning for 7 Gray per fraction (7[[ce:hsp sp="0.25"/]]Gy/#) was done for Co-60 HDR brachytherapy unit following the American Brachytherapy Society (ABS) guidelines. All the patients were treated with 3# with one week interval between fractions.

Results

The mean dose to high risk clinical target volumes (HRCTV) for D₉₀ (dose to 90% volume) was found to be 102.05% (Standard Deviation (SD): 3.07). The mean D_2cc (dose to 2 cubic centimeter volume) of the bladder, rectum and sigmoid were found to be 15.9[[ce:hsp sp="0.25"/]]Gy (SD: 0.58), 11.5[[ce:hsp sp="0.25"/]]Gy (SD: 0.91) and 4.1[[ce:hsp sp="0.25"/]]Gy (SD: 1.52), respectively.

Conclusion

The target coverage and doses to organs at risk (OARs) were achieved as per the ABS guidelines. Hence, it can be concluded that the Co-60 HDR brachytherapy unit is a good choice especially for the centers with a small number of brachytherapy procedures as no frequent source replacement is required like in an Ir-192 HDR unit.