Application of tangent-arc technology for deep inspiration breath-hold radiotherapy in left-sided breast cancer

Yucheng Li; Wenming Zhan; Yongshi Jia; Hanchu Xiong; Baihua Lin; Qiang Li; Huaxin Liu; Lingyun Qiu; Yinghao Zhang; Jieni Ding; Chao Fu; Weijun Chen

doi:10.3389/fonc.2023.1145332

Application of tangent-arc technology for deep inspiration breath-hold radiotherapy in left-sided breast cancer

Front Oncol. 2023 Aug 18:13:1145332. doi: 10.3389/fonc.2023.1145332. eCollection 2023.

Authors

Affiliations

¹ Cancer Center, Department of Radiation Oncology, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, Zhejiang, China.
² Department of Tumor Radiochemotherapy, Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China.

Abstract

Objective: To explore the advantages of dosimetry and the treatment efficiency of tangent-arc technology in deep inspiration breath-hold radiotherapy for breast cancer.

Methods: Forty patients with left-sided breast cancer who were treated in our hospital from May 2020 to June 2021 were randomly selected and divided into two groups. The first group's plan was a continuous semi-arc that started at 145° ( ± 5°) and stopped at 325° ( ± 5°). The other group's plan, defined as the tangent-arc plan, had two arcs: the first arc started at 145° ( ± 5°) and stopped at 85° ( ± 5°), and the second arc started at 25° ( ± 5°) and stopped at 325° ( ± 5°). We compared the target dose, dose in organs at risk (OARs), and treatment time between the two groups.

Results: The target dose was similar between the continuous semiarc and tangent-arc groups. The V₅ of the right lung was significantly different between the two groups (Dif 5.52, 95% confidence interval 1.92-9.13, t=3.10, P=0.004), with the patients in the continuous semi-arc and tangent-arc groups having lung V₅ values of (9.16 ± 1.62)%, and (3.64 ± 0.73)%, respectively. The maximum dose to the spinal cord was (1835.88 ± 222.17) cGy in the continuous semi-arc group and (599.42 ± 153.91) cGy in the tangent-arc group, yielding a significant difference between the two groups (Dif 1236.46, 95% confidence interval 689.32-1783.6, t=4.57, P<0.001). The treatment times was (311.70 ± 60.45) s for patients in the continuous semi-arc group and (254.66 ± 40.73) s for patients in the tangent-arc group, and there was a significant difference in the mean number of treatment times between the two groups (Dif 57.04, 95% confidence interval 24.05-90.03, t=3.5, P=0.001).

Conclusion: Both the continuous semi-arc and tangent-arc plans met the clinical prescription dose requirements. The OARs received less radiation with the tangent-arc plan than the continuous semi-arc plan, especially for the lung (measured as V₅) and the spinal cord (measured as the maximum dose). Tangent-arc plan took significantly less time than the continuous semi-arc, which can greatly improve treatment efficiency. Therefore, tangent-arc plans are superior continuous semi-arc plans for all cases.

Keywords: continuous semi-arc; deep inspiration breath-hold; dosimetry; left breast cancer; organ of risk; tangent-arc.

Grants and funding

This research was partially supported by the National Natural Science Foundation of China (82102814), this research was supported by Zhejiang Provincial Natural Science Foundation of China under Grant No. GF21H180053, and the Medical and Health Research Project of Zhejiang Province (2021PY002).