Algan O, Fowble B, McNeeley S, Fein D
Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA 19111, USA.
Int J Radiat Oncol Biol Phys. 1998 Mar 15;40(5):1137-40. doi: 10.1016/s0360-3016(97)00939-5.
The prone position has been advocated for women with large pendulous breasts undergoing breast-conserving treatment with radiation therapy. However, there is no information in the literature regarding the coverage of the target volume with this technique. The purpose of this study was to evaluate the effectiveness of the prone treatment position in including at least the biopsy cavity with a 2-cm margin.
Eleven consecutive patients who underwent CT simulation in the prone position were included in this study. Patients underwent CT simulation in the prone position using a flat platform containing an aperture for the breast to hang through in a dependent fashion. CT slices were 5-mm thick taken at 3-mm intervals. The biopsy cavity was localized and outlined on sequential CT images using the surgical clips (when present) as well as the residual seroma. A 2-cm margin was included around the biopsy cavity to define the minimal target volume (mTV). Lateral fields were used for treatment planning. The beam arrangements were considered adequate if the mTV was totally included in the lateral fields.
Median age of the patient population was 55 years. Bra sizes ranged from 36A-44DD. The majority of patients had mammographically detected T1 lesions. Median volume of the biopsy cavity was 48 cm3. Five of 11 (45%) patients underwent reexcision of the biopsy cavity, and 6 of 11 (55%) had surgical clips placed in the biopsy cavity. Overall, 8 of 11 (73%) patients did not have the entire mTV included in the lateral opposed tangential fields in the prone position. This was especially true in patients whose biopsy cavity extended down to the chest wall. There were no other clinical factors that could predict for the adequacy of coverage in the prone position.
Special attention must be paid to the location of the surgical clips to determine the proximity of the biopsy cavity to the chest wall, or CT simulation should be performed to determine the exact location of the biopsy cavity prior to selecting patients with large pendulous breasts for treatment in the prone position.
对于接受保乳放疗的乳房下垂较大的女性，俯卧位已被提倡采用。然而，文献中没有关于该技术对靶区覆盖情况的信息。本研究的目的是评估俯卧位治疗在至少包括有2厘米切缘的活检腔方面的有效性。
本研究纳入了11例连续在俯卧位进行CT模拟的患者。患者在俯卧位使用一个带有使乳房能下垂穿过的孔的平板平台进行CT模拟。CT扫描层厚5毫米，层间距3毫米。利用手术夹（如有）以及残留的血清肿在连续的CT图像上定位并勾勒出活检腔。在活检腔周围包括2厘米的切缘以确定最小靶区体积（mTV）。使用侧野进行治疗计划。如果mTV完全包含在侧野中，则认为射野布置是合适的。
患者人群的中位年龄为55岁。胸罩尺寸范围从36A到44DD。大多数患者通过乳腺钼靶检查发现为T1期病变。活检腔的中位体积为48立方厘米。11例患者中有5例（45%）对活检腔进行了再次切除，11例中有6例（55%）在活检腔放置了手术夹。总体而言，11例患者中有8例（73%）在俯卧位时，其整个mTV未完全包含在侧对侧切线野中。活检腔延伸至胸壁的患者尤其如此。没有其他临床因素能够预测俯卧位时覆盖的充分性。
必须特别注意手术夹的位置，以确定活检腔与胸壁的接近程度，或者在选择乳房下垂较大的患者进行俯卧位治疗之前，应进行CT模拟以确定活检腔的确切位置。
