Evaluation of the anatomical parameters for normal tissue sparing in the prone position radiotherapy with small sized left breasts
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Hyunjung Kim1,2, Jinyoung Kim1
1Department of Radiation Oncology, Inje University Haeundae Paik Hospital, Busan, Korea
2Department of Radiation Oncology, Yonsei University College of Medicine, Seoul, Korea
Jinyoung Kim, email: Jin0416@gmail.com
Keywords: breast cancer, prone position, small breast, radiotherapy, heart saving
Received: August 24, 2016 Accepted: October 07, 2016 Published: October 14, 2016
Prone position radiotherapy for a small (< 750 cm3) breast is controversial because of the variable benefits for the irradiated heart volume. The objective anatomical parameters related with chest wall shape that can determine the heart dose sparing patients in the prone position.
Twenty-one patients underwent CT-simulation in supine and prone position. Dose volume parameters were compared and the objective indexes such as the Haller index, anthropometric index, mid-sternum thickness, and central lung distance (CLD) were evaluated the relationship between the shape of the chest wall and irradiated normal tissue volume in prone position.
The median breast volume was 440.10 cm3 (range, 151.5–727.41 cm3). There was no difference of breast target volume between supine and prone position (p = 0.178). The Haller index under 2.5 (p = 0.046), an anthropometric index over 0.05 (p = 0.007), and the CLD over 2 (p = 0.023) conferred a greater heart sparing effect in the prone position.
In conclusions, the objective anatomical parameters related chest wall shape predict the decrease in irradiated heart volume in the prone position. Therefore, it is possible to screen for patients with a reduced heart volume irradiation among those with small breasts before applying prone position radiotherapy.
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