Evaluation of the anatomical parameters for normal tissue sparing in the prone position radiotherapy with small sized left breasts

Abstract

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.

Interobserver Variability of Target Volumes Delineated in the Supine and Prone Positions Based on Computed Tomography Images for External-Beam Partial Breast Irradiation After Breast-Conserving Surgery: A Comparative Study

“…In our study, all enrolled patients had a seroma clarity score <3, and we delineated the TB based on only the surgical clips. In addition, several studies have verified that the prone position has a significant advantage over the supine position in the conformity index of the targets (27,33). On the other hand, our results further indicated that compared with the supine position, the prone position led to a greater CTV intersection (greater by 5.79 cm 3 ).…”

External-beam partial breast irradiation in a supine versus prone position after breast-conserving surgery for Chinese breast cancer patients

“…Moreover, Kim et al . 17 verified that although there was no difference in the HI between the supine and prone positions, yet a significant advantage in the prone position was found in the CI. Breast and regional lymph nodes can be treated with an equal or better dose distribution in the target volumes in the prone position than in the supine position.…”

“… 16 also confirmed that for patients who underwent WBI, a small but statistically significant difference was evident in the whole breast CTV between the prone and supine positions (57 cc lower in the prone position). However, for patients with small breasts (<750 cm 3 ) who underwent radiotherapy in the prone position, no obvious variations in the breast target volume were found between the supine and prone positions 17 . In our study, the enrolled patients with breast volumes less than 750 cm 3 comprised 63% of all patients.…”

“…Controversy exists regarding WBI treatment in the prone position in terms of target volume coverage and the dose distribution in the target volumes 12 , 13 , 17 . Bergom et al .…”

Breast Radiotherapy-Related Cardiotoxicity. When, How, Why. Risk Prevention and Control Strategies

“…Among the maneuvers that allow the chest wall to be separated from the heart are irradiation in the prone position as well as techniques for monitoring respiratory movement [ 73 , 74 , 75 ].…”