The Effect of Deep Inspiration Breath-Hold Technique on Right Coronary Artery, Heart, and Liver Doses in Right Breast Cancer Radiotherapy


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Semiz V., Aydın B., Gülşan D., Ataç E., Özkaya E., Kınay Ş., ...More

65th Annual Meeting, ASTRO 2023, California, United States Of America, 30 September 2023, vol.117

  • Publication Type: Conference Paper / Summary Text
  • Volume: 117
  • Doi Number: 10.1016/j.ijrobp.2023.06.2048
  • City: California
  • Country: United States Of America
  • Dokuz Eylül University Affiliated: Yes

Abstract

Purpose/Objective(s): The deep inspiration breath-hold (DIBH) approach has been thoroughly researched with the aim of reducing radiation exposures to normal tissues in breast cancer patients. Although heart and lung toxicity are widely addressed in many literature, radiation associated liver toxicity and dose constraints for the right coronary artery (RCA)are no twell studied in relation to breast radiotherapy. Additionally, very few studies have investigated the relationship between doses to cardiac substructures. This study aimed to determine the effect of the DIBH technique on the right coronary artery (RCA) region, cardiac substructures, and liver dose in right breast cancer irradiation.

Materials/Methods: Between January 2022 and December 2022, thirty-five right breast cancer patients who previously received breast-surgery underwent computed tomography (CT) simulation with both free-breathing (FB) and DIBH techniques. Patients were contoured by a radiation oncologist on the scans using the Treatment Planning System. For cardiac substructures, reference atlas contours were used for accurate delineation and to reduce interobserver variation. Each patient underwent two treatment plans for both the DIBH and FB datasets.The plan comprised the FB and DIBH techniques, and the doses to the cardiac substructures, ipsilateral lung, RCA region, and liver were compared using atwo-tailed paired t-test. Radiotherapy was delivered with a Linac with the prescription dose of 50Gy in 25 fractions.

Results: ForbothFBandDIBHirradiationgroups, the mean radiation doses to the ipsilateral lung, heart, and RCA region in patients with FB and DIBH techniques were; 14.67Gy, 2.33Gy, 4.88Gy and 12.05Gy, 1.34Gy and 3.29Gy respectively. The mean radiation doses to the cardiac substructures; for the left ventricle, right ventricle, left atrium,and right atrium for the FB were 1.08Gy, 1.79Gy, 4.11Gy, and for DIBH, 0.49Gy, 1.49Gy, 0.95Gy, and 2.61Gy, respectively. For the DIBH group, the liver maximum dose (p<0.01), right lung mean dose (p=0.001), heart maximum dose (p=0.009), RCA mean dose (p=0.020), RCA maximum dose(p=0.008), RCA V5 dose(p=0.035), right atrium maximum dose (p=0.009) and right ventricle mean dose (p=0.040) were significantly lower than in patients treated in the non-gated group.

Conclusion: DIBH resulted in considerable displacement of the liver away from the high-dose target region, such that the volume of liver in the high dose region was reduced. Additionally, the use of the DIBH technique in right breast cancer irradiation effectively reduces the radiation doses to the cardiac substructures, such as the left ventricle, right ventricle, left atrium, right atrium, RCA region, and lungs. DIBH could lead to substantial sparing of these structures with the right breast cancer radiotherapy. Future prospective studies are required to determine whether improvements to dose-distribution will translate in to improved toxicity outcomes.