A Dosimetric Study Comparing Different Radiotherapy Planning Techniques With and Without Deep Inspiratory Breath Hold for Breast Cancer.

Objective: To analyze whether deep inspiratory breath hold (DIBH) would be dosimetrically beneficial irrespective of radiotherapy planning techniques for patients with left breast cancers requiring adjuvant radiotherapy. Methods: Planning CT scans were taken in free-breathing (FB) as well as deep-inspiration breath hold (DIBH) for patients requiring adjuvant radiotherapy for left breast cancers. After registration, three radiotherapy plans - 3D-conformal radiotherapy (3DCRT), intensity modulated RT (IMRT), and volumetric modulated arc-therapy (VMAT) - were generated for both FB and DIBH scans for each patient. The dose-volume parameters were collected from the dose-volume histogram and analyzed. A paired Findings: The study was conducted on thirteen patients. The mean dose of the left lung was reduced with DIBH by 32%, 24%, and 6% (8.6 Gy, 6.6 Gy, and 6.4 Gy) with 3DCRT, IMRT, and VMAT, respectively. The mean heart dose was reduced by 3.3 Gy (2.2 vs 5.5 Gy), 2.2 Gy (7.5 vs 9.7 Gy), and 1.2 Gy (5.8 vs 7 Gy) with 3DCRT, IMRT, and VMAT with DIBH. Similarly, the left anterior descending artery (LAD) mean dose was relatively reduced by 80%, 34%, and 20% when compared with the FB scans for 3DCRT, IMRT, and VMAT respectively, with max dose in the 3DCRT plan. Novelty/Applications: DIBH appears to have maximum benefit in achieving a better sparing of organs-at-risk for patients being considered for 3DCRT, and to a lesser extent with even IMRT and VMAT techniques.