Potential benefits of using cardiac gated images to reduce the dose to the left anterior descending coronary during radiotherapy of left breast and internal mammary nodes

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• 作者：C.E. de Almeida^a ; ^b ; N. Fournier-Bidoz^a ; C. Massabeau^a ; A. Mazal^a ; P.C. Canary^b ; I.R. Kuroki^c ; F. Campana^a ; A. Fourquet^a ; Y.M. Kirova^a ; ^{youlia.kirova@curie.net}
• 关键词：Breast cancer radiotherapy ; Heart ; Coronary artery ; Cardiac gating
• 刊名：Cancer Radiotherapie
• 出版年：2012
• 期刊代码：45_12783218
• 类别：med
• 出版时间：February, 2012
• 卷：16
• 期：1
• 页码：44-51
• 文件大小：1073 K

摘要

Purpose

To assess the benefits of using cardiac gated images for treatment planning of breast and internal mammary nodes.

Patients and methods

Inspiration breath hold computed tomography (CT) series acquired at prospectively gated diastolic phase were used for planning. Three different techniques were compared. Technique A used tangents and an internal mammary nodes field covering the three first inter-rib spaces; technique B used an extended internal mammary nodes including part of the medial breast in junction with tangential fields; the 3^rd technique used helical tomotherapy. For each technique, two treatment plans were performed: one plan (plan-01) where mean dose and V₂₅ to the heart were considered for plan evaluation and a second plan (plan-02) where the irradiation of the left anterior descending artery was minimized.

Results

V₂₅ to the heart was found to be less than 5%for all six plans. Mean doses to the heart were within 4.8 to 7.2 Gy. By attempting to lower the dose to the left anterior descending artery, heart D_mean was decreased by 20-30%for the two techniques A and B while being unchanged for tomotherapy. Regarding target coverage, there was no marked difference between plans where only heart dose was considered (plans-01) and plans where the left anterior descending artery dose was minimized (plans-02). When the left anterior descending artery dose was part of plan evaluation, D_mean to the left anterior descending artery could be decreased by 24, 19 and 9%for techniques A, B and tomotherapy respectively. The three techniques exposed segments of the left coronary to different levels of dose.

Conclusion

This study showed that evaluation of the dose to the left anterior descending artery coronary may change the treatment strategy. Cardiac gated images without IV contrast permitted a good visualization of the coronaries in order to optimize the dose on these structures. In addition to heart V_25, the dose to the coronaries should be included in prospective studies on radiotherapy related heart toxicity in association with all additional risk factors.