A patient-based dosimetric study of intracavitary and interstitial brachytherapy in advanced stage carcinoma of the cervix.

Anil K Bansal,Goura K Rath,Pramod K Julka,Manoj K Semwal,Daya N Sharma,Sanjay Thulkar

doi:10.1120/jacmp.v15i3.4509

Abstract

Intracavitary brachytherapy (ICBT) and interstitial brachytherapy (IB) techniques are commonly practiced for treating carcinoma of the cervix, either alone or in combination with external beam radiotherapy. Both these brachytherapy techniques have their own advantages and limitations in terms of tumor coverage and normal tissue sparing. Limited studies have been reported comparing the dosimetric features of these two techniques, especially from a single institution. We carried out a prospective clinical dosimetric comparison between ICBT and IB for patients treated at one center to bring out the inherent dosimetric features of these to two techniques. The study was carried out on 26 patients treated with ICBT and 55 with IB using CT‐based planning. Of the 55 patients treated with IB, 27 included tandem source loading (IBT) and 28 without the tandem loading (IBWT). The high‐dose volumes covered by 200% and 180% isodose surfaces were considerably larger in ICBT as compared to IB, whereas the treated volume was larger in IB as compared to ICBT. The bladder and rectal doses were the highest in ICBT and IBWT, respectively. The larger treated volume in IB as compared to ICBT was mainly because patients with larger tumor volumes were generally considered for IB. The results also indicated that in interstitial brachytherapy, better rectal sparing was achieved by including the tandem for treatment delivery.PACS numbers: 87.53.Bn, 87.53.Jw, 87.55.D‐, 87.55.dk

Highlights

Brachytherapy is a crucial component of radiotherapy in the management of carcinoma of the cervix
While estimating the high-dose volumes without applicator volumes from the dose-volume histograms (DVH), it was found out that mainly ovoids contributed to the applicator volumes, as compared to tandem and needles
The treated volume length is not much different among all categories of implants, whereas the width of the implant is larger for interstitial brachytherapy (IB) implants as compared to intracavitary brachytherapy (ICBT) implants

Summary

Introduction

Brachytherapy is a crucial component of radiotherapy in the management of carcinoma of the cervix. A water phantom-based study involving bladder and rectum dose measurements in ICBT has been reported by Bansal et al[12] Patient-based dosimetric comparisons reported in literature are generally retrospective studies related to patients treated at different institutions with ICBT and IB modalities.[13,14,15] In the present work, we carried out a prospective dosimetric study on two groups of patients planned and treated with Ir-192-based HDR ICBT and IB for advanced stage carcinoma cervix at one center by a common team of physicians and physicists. The variations due to external factors such as differences in contouring and treatment planning protocols were minimized, making the comparison between the two brachytherapy techniques more meaningful. Various parameters such as treated volume, total reference air kerma (TRAK), and doses received by OARs were estimated for the two groups of patients. The present study only compares physical doses without consideration of the radiobiological factors

Methods

Results

Discussion

Conclusion