Dosimetric Outcomes of Deep Inspiration Breath-Hold (DIBH) Technique in Terms of Normal Tissue Sparing for Right-Sided Breast Cancer Irradiation: A Single-Institution Experience

Abstract Introduction Deep inspiration breath-hold (DIBH) technique is commonly used in left breast cancer irradiation as it has shown to reduce cardiac and pulmonary doses. DIBH technique has also shown to reduce critical organ doses in right-sided breast cancer patients. This study aimed to demonstrate the single-institution experience of dosimetric benefits of DIBH technique in irradiation of right breast carcinoma patients. Materials and Method Twenty consecutive patients who underwent adjuvant locoregional radiotherapy by DIBH technique for right-sided breast carcinoma were included retrospectively for analysis. Indications for use of DIBH for right-sided disease in our institution included presence of breast implant or need for irradiation of axillary and/or internal mammary nodal basin. For all these patients, planning computed tomography (CT) was obtained in both free breathing (FB) and deep inspiration breath hold (DIBH) using indexed breast board. Treatment was replanned in the FB planning CT slices, and dosimetric endpoints in terms of differences in PTV coverage and doses to lungs, heart, liver, and contralateral breast were compared. Radiation was delivered using either volumetric modulated arc therapy or intensity-modulated radiotherapy technique. Results There was no significant difference in PTV coverage between FB and DIBH scans showing similar plan qualities. The ipsilateral lung volume showed significant increase with subsequent decrease in the mean dose with DIBH compared to FB (from 14 Gy in the FB plan to 12 Gy with DIBH, p -value 0.01). Technique of DIBH significantly lowered the mean hepatic dose compared to FB technique (3.8 vs. 7.9 Gy, p -value: 0.0001). Contralateral lung mean dose also showed reduction of statistical significance in DIBH. There was significant difference in the mean dose to the heart between the two techniques, as well as in the max dose, which was reduced significantly with DIBH. Contralateral breast mean dose was also reduced with DIBH, though the difference was not statistically significant. Conclusion DIBH technique showed significant dosimetric benefit in terms of reduced critical organ doses, providing a potential for incorporation into radiotherapy of right-sided breast carcinoma.