Radiation Oncology Department, Cancer Institute Hospital, Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo 135-8550, Japan; Graduate Division of Health Sciences, Komazawa University, 1-23-1, Komazawa, Setagaya-ku, Tokyo 154-8525, Japan.
Graduate Division of Health Sciences, Komazawa University, 1-23-1, Komazawa, Setagaya-ku, Tokyo 154-8525, Japan.
Phys Med. 2019 May;61:70-76. doi: 10.1016/j.ejmp.2019.04.018. Epub 2019 May 3.
(i) to investigate the capability of organ-at-risk (OAR) dose reduction with the jaw tracking (JT) technique in flattening filter-free (FFF) beams in lung stereotactic body radiation therapy (SBRT), (ii) to propose a novel metric to quantify the jaw movements during JT, and (iii) to examine the relationships between the quantified jaw movements and reduction rate of OAR doses.
The individual SBRT plans with volumetric modulated arc therapy using the JT technique (JT-VMAT) and VMAT plans with a fixed jaw (FJ-VMAT) were created for 15 patients, and dosimetric parameters were compared. A jaw tracking complexity score (JTCS) was defined and compared with the multi-leaf collimator (MLC) modulation complexity score (MCS). The correlations between the JTCS and reduction rate of OAR doses were examined.
The decrease of OARs doses was statistically significant in the JT-VMAT plans (1.2% in V20 of the lung and <1% in all other OARs). The correlations between the JTCS and MCS were not significant. There were significant correlations between the JTCS and the reduction rates in V, V, and D of the lung, D of the spinal cord, and D of the body.
A significant decrease of dosimetric parameters of OARs was found with JT-VMAT in FFF beams. This reduction is very small and probably not clinically relevant. JTCS, a novel metric to quantify the jaw movements during JT, was proposed, and the complexity of jaw movements did not correlate with that of the movements of MLC leaves. There were significant correlations between the JTCS and some dosimetric parameters of OARs.
（i）研究在肺立体定向体部放射治疗（SBRT）中使用 Jaw Tracking（JT）技术在平坦过滤（FF）射束中减少危及器官（OAR）剂量的能力，（ii）提出一种新的指标来量化 JT 期间的下颌运动，（iii）研究量化的下颌运动与 OAR 剂量减少率之间的关系。
为 15 名患者创建了使用 JT 技术的容积调强弧形治疗（JT-VMAT）的个体化 SBRT 计划和具有固定下颌（FJ-VMAT）的调强弧形治疗（VMAT）计划，并比较了剂量学参数。定义了 Jaw Tracking 复杂性评分（JTCS），并将其与多叶准直器（MLC）调制复杂性评分（MCS）进行比较。检查了 JTCS 与 OAR 剂量减少率之间的相关性。
JT-VMAT 计划中 OAR 剂量的降低具有统计学意义（肺 V20 降低 1.2%，所有其他 OAR 降低<1%）。JTCS 与 MCS 之间的相关性不显著。JTCS 与肺的 V、V 和 D、脊髓的 D 和身体的 D 的减少率之间存在显著相关性。
在 FFF 射束中，使用 JT-VMAT 发现 OAR 的剂量学参数显著降低。这种减少非常小，可能没有临床意义。提出了一种新的指标来量化 JT 期间的下颌运动，下颌运动的复杂性与 MLC 叶片的运动复杂性没有相关性。JTCS 与一些 OAR 的剂量学参数之间存在显著相关性。
