Ranger Alison, Dunlop Alex, Grimwood Alex, Durie Emily, Donovan Ellen, Havilland Jo, Harris Emma, McNair Helen, Kirby Anna M
Royal Marsden NHS Foundation Trust, Sutton, Surrey, United Kingdom.
Clin Transl Radiat Oncol. 2021 Feb 11;27:164-168. doi: 10.1016/j.ctro.2021.02.003. eCollection 2021 Mar.
Deep-inspiration breath-hold (DIBH) reduces radiation dose to the heart in patients undergoing locoregional breast radiotherapy. In the context of tangential irradiation of the breast/ chest wall, a voluntary breath hold (vDIBH) technique has been shown to be as reproducible as a machine-assisted breath hold technique using the active breathing co-ordinator (ABC™, Elekta, Crawley, UK, ABC_DIBH). This study compares set-up reproducibility for vDIBH versus ABC_DIBH in patients undergoing volumetric-modulated arc radiotherapy (VMAT) for breast cancer, both with and without wax bolus.
Patients with breast cancer requiring pan regional lymph node VMAT +/- wax bolus in breath-hold were CT scanned in vDIBH and ABC_DIBH. Patients were randomised to receive one technique for fractions 1-7 and the other for fractions 8-15. Daily cone beam computed tomography (CBCT) was performed and registered to planning-CT using bony anatomy. Within-patient comparisons of mean daily chest wall position were made using a paired -test. Population, systematic (∑) and random errors (α) were estimated. Intrafraction reproducibility was assessed by comparing chest wall position and diaphragm movement between consecutive breath holds on CBCT.
16 patients were recruited. All completed treatment with both techniques (9 patients with wax bolus, 7 patients without). CBCT derived ∑ were 2.1-6.4 mm (ABC_DIBH) and 2.1-4.9 mm (vDIBH), α were 1.7-2.6 mm (ABC_DIBH) and 2.2-2.7 mm (vDIBH) and mean daily chest wall displacements (MD) were 0.0-1.5 mm (ABC_DIBH) and 0.1-1.6 vDIBH (all non-significant). Chest wall and diaphragm position was equivalent between consecutive breath holds in ABC and vDIBH (median difference 1.0 mm and 0.8 mm respectively, non significant) demonstrating equivalent intrafraction reproducibility.
This study demonstrates that a simple voluntary breath hold technique is feasible in combination with VMAT (+/- bolus) and is as reproducible as ABC_DIBH with VMAT for the irradiation of the breast and axillary and IMC lymph nodes in breast cancer patients.
深吸气屏气（DIBH）可降低局部乳腺放疗患者心脏的辐射剂量。在乳腺/胸壁切线照射的情况下，已证明一种自主屏气（vDIBH）技术与使用主动呼吸协调器（ABC™，医科达公司，克劳利，英国，ABC_DIBH）的机器辅助屏气技术具有相同的可重复性。本研究比较了接受容积调强弧形放疗（VMAT）治疗乳腺癌的患者在使用和不使用蜡块时，vDIBH与ABC_DIBH的摆位可重复性。
需要在屏气状态下进行全区域淋巴结VMAT±蜡块的乳腺癌患者在vDIBH和ABC_DIBH状态下进行CT扫描。患者被随机分配，在第1 - 7次分割中接受一种技术，在第8 - 15次分割中接受另一种技术。每天进行锥形束计算机断层扫描（CBCT），并使用骨性解剖结构与计划CT进行配准。使用配对t检验对患者每日胸壁平均位置进行患者内比较。估计总体误差、系统误差（∑）和随机误差（α）。通过比较CBCT上连续屏气之间的胸壁位置和膈肌运动来评估分次内可重复性。
招募了16名患者。所有患者均完成了两种技术的治疗（9名患者使用蜡块，7名患者未使用）。CBCT得出的∑分别为2.1 - 6.4毫米（ABC_DIBH）和2.1 - 4.9毫米（vDIBH），α分别为1.7 - 2.6毫米（ABC_DIBH）和2.2 - 2.7毫米（vDIBH），每日胸壁平均位移（MD）分别为0.0 - 1.5毫米（ABC_DIBH）和0.1 - 1.6毫米（vDIBH）（均无统计学意义）。ABC和vDIBH中连续屏气之间的胸壁和膈肌位置相当（中位数差异分别为1.0毫米和0.8毫米，无统计学意义），表明分次内可重复性相当。
本研究表明，一种简单的自主屏气技术与VMAT（±蜡块）联合使用是可行的，并且在照射乳腺癌患者的乳腺、腋窝和内乳淋巴结方面，与ABC_DIBH联合VMAT具有相同的可重复性。
