Gynecological brachytherapy for postoperative endometrial cancer: dosimetric analysis (Ir-192 vs Co-60)

Abstract

Introduction

Endovaginal brachytherapy treatment dosimetry differences were studied using Ir-192 or Co-60 sources for postoperative endometrial cancer.

Materials and methods

A prospective descriptive study was conducted. Thirty-six dosimetry plans of different patients were studied (15 by Ir-192 and 21 by Co-60). Variables studied included D2cc Rectum, D2cc Bladder, D2cc Sigmoid, dose percentage at point 0 (applicator surface on the top of the cylinder) and dose percentage at point 1 (5 mm deep on the top of the cylinder). A comparative analysis was performed of the values obtained from each variable between Ir-192 and Co-60 treatments. We compared average of each variables between Iridium and Cobalt by T Student for independent samples (SPSS 22).

Results

There were no significant differences on using Ir-192 or Co-60 by variables, except for dose percentage at point 1 in which we detected significant differences (Table 1).

The results

Variables

Sources

Iridium 192

Cobalt 60

D2cc Rectum

(mean dose)

[rank]

6.01 Gy [3.99–7.90]

5.28 Gy [3.87–6,34]

D2cc Bladder

(mean dose)

[rank]

5.82 Gy [4.20–8.38]

5.05 Gy [2.23–6.95]

D2cc Sigmoid

(mean dose)

[rank]

4.43 Gy [1.66–6.67]

2.33 Gy [0.60–4.28]

Dose percentage at point 0^a

(mean)

[rank]

210.74% [120.90–234.90]

204.75% [177.10–223]

Dose percentage at point 1^b

(mean)

[rank]

93.49% [87.30–100.60]

100.11% [96.70–102]

^aPoint 0: point to the applicator surface

^bPoint 1: point to 5 mm applicator surface

Discussion

Brachytherapy treatment dosimetry plans are similar using Ir-192 or Co-60, except dose percentage at point 1. In the scientific literature, some differences exist and there are some advantages in using cobalt.

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