Dose volume histogram analysis of normal structures associated with accelerated partial breast irradiation delivered by high dose rate brachytherapy and comparison with whole breast external beam radiotherapy fields

Alexandra J Stewart,Robert A Cormack,Jorgen L Hansen,Subhakar Mutyala,Phillip M Devlin,Atif J Khan,Desmond A O'Farrell

doi:10.1186/1748-717x-3-39

Abstract

PurposeTo assess the radiation dose delivered to the heart and ipsilateral lung during accelerated partial breast brachytherapy using a MammoSite™ applicator and compare to those produced by whole breast external beam radiotherapy (WBRT).Materials and methodsDosimetric analysis was conducted on patients receiving MammoSite breast brachytherapy following conservative surgery for invasive ductal carcinoma. Cardiac dose was evaluated for patients with left breast tumors with a CT scan encompassing the entire heart. Lung dose was evaluated for patients in whom the entire lung was scanned. The prescription dose of 3400 cGy was 1 cm from the balloon surface. MammoSite dosimetry was compared to simulated WBRT fields with and without radiobiological correction for the effects of dose and fractionation. Dose parameters such as the volume of the structure receiving 10 Gy or more (V10) and the dose received by 20 cc of the structure (D20), were calculated as well as the maximum and mean doses received.ResultsFifteen patients were studied, five had complete lung data and six had left-sided tumors with complete cardiac data. Ipsilateral lung volumes ranged from 925–1380 cc. Cardiac volumes ranged from 337–551 cc. MammoSite resulted in a significantly lower percentage lung V30 and lung and cardiac V20 than the WBRT fields, with and without radiobiological correction.ConclusionThis study gives low values for incidental radiation received by the heart and ipsilateral lung using the MammoSite applicator. The volume of heart and lung irradiated to clinically significant levels was significantly lower with the MammoSite applicator than using simulated WBRT fields of the same CT data sets.Trial registrationDana Farber Trial Registry number 03-179

Highlights

Accelerated partial breast irradiation (APBI) is increasingly being used as an alternative to whole breast irradiation following wide local excision in selected patients with early stage low-risk breast cancer [1]
This study gives low values for incidental radiation received by the heart and ipsilateral lung using the MammoSite applicator
The volume of heart and lung irradiated to clinically significant levels was significantly lower with the MammoSite applicator than using simulated whole breast external beam radiotherapy (WBRT) fields of the same CT data sets

Summary

Introduction

Accelerated partial breast irradiation (APBI) is increasingly being used as an alternative to whole breast irradiation following wide local excision in selected patients with early stage low-risk breast cancer [1]. The majority of published series of patients treated with APBI have used brachytherapy [117]. Interstitial implants can be complex and operatordependant the MammoSite applicator (Hologic, Bedford, Massachusetts, USA) was developed to make APBI with brachytherapy more accessible and less invasive. Since this is a new technology, there is a paucity of long-term follow-up using this technique. The prospective series with the longest follow-up to date using the MammoSite catheter show low levels of ipsilateral breast recurrence with minimal incidence of tumor bed recurrence [2,14,16]

Methods

Results

Discussion

Conclusion