Helical tomotherapy with a complete-directional-complete block technique effectively reduces cardiac and lung dose for left-sided breast cancer

Hsin-Pei Yeh; Yu-Chuen Huang; Li-Ying Wang; Pei-Wei Shueng; Hui-Ju Tien; Chiu-Han Chang; San-Fang Chou; Chen-Hsi Hsieh

doi:10.1259/bjr.20190792

Helical tomotherapy with a complete-directional-complete block technique effectively reduces cardiac and lung dose for left-sided breast cancer

Br J Radiol. 2020 Apr;93(1108):20190792. doi: 10.1259/bjr.20190792. Epub 2020 Jan 21.

Authors

Hsin-Pei Yeh¹, Yu-Chuen Huang^{2

3}, Li-Ying Wang^{4

5}, Pei-Wei Shueng^{1

6}, Hui-Ju Tien^{1

7}, Chiu-Han Chang¹, San-Fang Chou⁸, Chen-Hsi Hsieh^{1

6

9}

Affiliations

¹ Division of Radiation Oncology, Department of Radiology, Far Eastern Memorial Hospital, New Taipei City, Taiwan, Republic of China.
² Department of Medical Research, China Medical University Hospital, Taichung, Taiwan, Republic of China.
³ School of Chinese Medicine, China Medical University, Taichung, Taiwan, Republic of China.
⁴ Physical Therapy Center, National Taiwan University Hospital, Taipei, Taiwan, Republic of China.
⁵ School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Taipei, Taiwan, Republic of China.
⁶ Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan, Republic of China.
⁷ Department of Biomedical Imaging and Radiological Science, National Yang- Ming University, Taipei, Taiwan.
⁸ Department of Medical Research, Far Eastern Memorial Hospital, New Taipei City, Taiwan, Republic of China.
⁹ Institute of Traditional Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan, Republic of China.

Abstract

Objectives: To evaluate the feasibility and optimal restricted angle of the complete-directional-complete block (CDCB) technique in helical tomotherapy (HT) by including regional nodal irradiation (RNI) with the internal mammary node (IMN) in left-sided breast cancer.

Methods: Ten left-sided breast cancer patients treated with 50 Gy in 25 fractions were compared with five-field intensity-modulated radiation therapy (5F-IMRT) and six types of HT plans. In the HT plans, complete block (CB), organ-based directional block (OBDB) and CDCB with different restricted angles were used.

Results: The conformity index (CI) between the CDCB_0,10,15,20 and 5F-IMRT groups was similar. Compared to CB, OBDB and 5F-IMRT, CDCB₂₀ resulted in a decreased ipsilateral mean lung dose. The low-dose region (V₅) of the ipsilateral lung in OBDB (84.0%) was the highest among all techniques (p < 0.001). The mean dose of the heart in CB was significantly reduced (by 11.5-22.4%) compared with other techniques. The V₃₀ of the heart in CDCB₂₀ (1.9%) was significantly lower than that of CB, OBDB and 5F-IMRT. Compared to the mean dose of the left anterior descending (LAD) artery of 5F-IMRT (27.0 Gy), CDCB₀, CDCB₁₀, CDCB₁₅, CDCB₂₀ and OBDB reduced the mean dose effectively by 31.7%, 38.3%, 39.6%, 42.0 and 56.2%, respectively. Considering the parameters of the organs-at-risk (OARs), CDCB_10,15,20 had higher expectative values than the other techniques (p = 0.01).

Conclusions: HT with the CDCB technique is feasible for treating left-sided breast cancer patients. The CDCB_10-20 techniques not only achieved similar planning target volume coverage, homogeneity and dose conformity but also allowed better sparing of the heart and bilateral lungs.

Advances in knowledge: For left-sided breast cancer patients whose RNI field includes the IMN, heart avoidance is an important issue. The CDCB technique achieved good PTV coverage, homogeneity and dose conformity and allowed better sparing of the mean dose of the lung, the LAD artery, and the heart and reduced the V₃₀ of the heart.

MeSH terms

Dose Fractionation, Radiation
Feasibility Studies
Female
Heart / radiation effects*
Humans
Lung / radiation effects*
Lymphatic Irradiation / methods*
Organs at Risk / diagnostic imaging
Organs at Risk / radiation effects*
Radiation Injuries / prevention & control*
Radiotherapy Planning, Computer-Assisted / methods
Radiotherapy, Intensity-Modulated / methods*
Unilateral Breast Neoplasms / diagnostic imaging
Unilateral Breast Neoplasms / radiotherapy*