Deep inspirational breast hold (DIBH) for right breast irradiation: Improved sparing of liver and lung tissue

Thomas Mader; Rachel Pace; Rui T Boucas da Silva; Lukas Erwin Johannes Adam; Gabriela Näf; Christopher Charles Winter; Mania Maria Aspradakis; Marco Radovic; Aristotelis Spyridonidis; Stefanie Hayoz; Brigitta Gertrud Baumert

doi:10.1016/j.ctro.2024.100731

Deep inspirational breast hold (DIBH) for right breast irradiation: Improved sparing of liver and lung tissue

Clin Transl Radiat Oncol. 2024 Jan 23:45:100731. doi: 10.1016/j.ctro.2024.100731. eCollection 2024 Mar.

Affiliations

¹ Institute of Radiation Oncology, Cantonal Hospital Graubünden, Chur, Switzerland.
² Department of Radiation Oncology, Cantonal Hospital Winterthur, Winterthur, Switzerland.
³ Department of Radiation Oncology, University Hospital Basel, Basel, Switzerland.
⁴ Swiss Group for Clinical Cancer Research (SAKK), Competence Center, Bern, Switzerland.

Abstract

Objective: To reduce liver and lung dose during right breast irradiation while maintaining optimal dose to the target volume. This dose reduction has the potential to decrease acute side effects and long-term toxicity.

Materials and methods: 16 patients treated with radiation therapy for localized carcinoma of the right breast were included retrospectively. For the planning CT, each patient was immobilised on an indexed board with the arms placed above the head. CT scans were acquired in free-breathing (FB) as well as with deep inspiration breath hold (DIBH). Both scans were acquired with the same length. Planning target volumes (PTV's) were created with a 5 mm margin from the respective clinical target volumes (CTV's) on both CT datasets. The liver was outlined as scanned. Dose metrics evaluated were as follows: differences in PTV coverage, dose to the liver (max, mean, V90%, V50%, V30%), dose to lung (mean, V20Gy, relative electron density) and dose to heart (Dmax). The p-values were calculated using Wilcoxon signed-rank tests. A p-value was significant when <0.05.

Results: Differences in PTV coverage between plans using FB and DIBH were less than 2 %. Maximum liver dose was significantly less using DIBH: 17.5 Gy versus FB: 40.3 Gy (p < 0.001). The volume of the liver receiving 10 % of the dose was significantly less using DIBH with 1.88 cm³ versus 72.2 cm³ under FB (p < 0.001). The absolute volume receiving 20 Gy in the right lung was larger using DIBH: 291 cm³ versus 230 cm³ under FB (p < 0.001) and the relative volume of lung receiving dose greater than 20 Gy was smaller with DIBH: 11.5 % versus 14 % in FB (p = 0.007). The relative electron density of lung was significantly less with DIBH: 0.59 versus 0.62 with FB, (p < 0.001). This suggests that the lung receives less dose due to its lower density when using DIBH.

Conclusion: Radiation of the right breast using DIBH spares liver and lung tissue significantly and thus carries the potential of best practice for right sided breast cancer.

Keywords: Breast cancer; Deep inspiration breath-hold (DIBH); Gating; IMRT; Liver; Lung; Treatment planning.