Ramezani Farkhani R, Gholamhosseinian H, Anvari K, Forghani M N
MSc, Department of Medical Physics, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
PhD, Department of Medical Physics, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
J Biomed Phys Eng. 2021 Feb 1;11(1):55-60. doi: 10.31661/jbpe.v0i0.2001-1046. eCollection 2021 Feb.
Breast cancer is the most common cancer among women. Considering the fact that a high dose is delivered in a single fraction of IORT, the evaluation of the dose at sensitive organs like thyroid is necessary.
The current study has aimed to evaluate the received dose to thyroid lobes in the breast IORT technique.
A total of 49 women with breast cancer undergoing IORT were enrolled in this cross-sectional study with census sampling. Immediately after tumor resection, a single dose of 20 Gray at the applicator surface was delivered using 50KV X-ray by an Intrabeam machine. The thyroid dose was detected using thermoluminescent detectors (TLD) 100 at the mid-thyroid line, left and right lobes.
The dose at the right and left lobes of the thyroid gland as well as the mid-thyroid line was found to be 40.18±35.44 mGy, 35.50±27.32 mGy, and 40.61±32.47 mGy, respectively. The right lobe received a significantly higher absorbed dose compared to the left lobe when the right breast was under IORT treatment. The same trend was seen with the left lobe and left breast under IORT treatment (P=0.0001 and P=0.018, respectively). The applicator size showed non-significant effects on the absorbed dose at the thyroid gland. Also, the applicator depth had a non-significant inverse effect on thyroid dose.
According to our findings, the absorbed dose at each thyroid lobe depends on the under-treatment side as well as the applicator size and depth (applicator upper surface distance from the skin).
乳腺癌是女性中最常见的癌症。鉴于术中放疗（IORT）单次分割给予高剂量，评估甲状腺等敏感器官的剂量很有必要。
本研究旨在评估乳腺癌IORT技术中甲状腺叶所接受的剂量。
本横断面研究采用普查抽样法，纳入了49例行IORT的乳腺癌女性患者。肿瘤切除后立即使用Intrabeam机器通过50KV X射线在施源器表面给予20格雷的单次剂量。使用热释光探测器（TLD）100在甲状腺中线、左右叶检测甲状腺剂量。
甲状腺左右叶以及甲状腺中线的剂量分别为40.18±35.44毫戈瑞、35.50±27.32毫戈瑞和40.61±32.47毫戈瑞。当右侧乳房接受IORT治疗时，右侧叶接受的吸收剂量显著高于左侧叶。左侧叶和左侧乳房接受IORT治疗时也出现同样趋势（分别为P = 0.0001和P = 0.018）。施源器尺寸对甲状腺吸收剂量无显著影响。此外，施源器深度对甲状腺剂量有不显著的反向影响。
根据我们的研究结果，每个甲状腺叶的吸收剂量取决于治疗侧以及施源器尺寸和深度（施源器上表面距皮肤的距离）。
