Stengl Christina, Christensen Jeppe B, Muñoz Iván D, Neuholz Alexander, Brons Stephan, Yukihara Eduardo G, Liermann Jakob, Jäkel Oliver, Vedelago José
Faculty of Medicine, University of Heidelberg, Im Neuenheimer Feld 672, Heidelberg 69120, Germany.
Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg 69120, Germany.
Phys Imaging Radiat Oncol. 2025 May 8;34:100775. doi: 10.1016/j.phro.2025.100775. eCollection 2025 Apr.
Carbon ion radiotherapy (CIRT) has demonstrated promising treatment outcomes for pancreatic cancer. However, breathing-induced organ motion can compromise the efficacy of the treatment, leading to under- or over-dosage within the target and organs at risk (OARs). In this work, the dose during CIRT was simultaneously measured at the target and OARs using an anthropomorphic phantom to evaluate the effectiveness of respiratory gating for compensating breathing motion.
The Pancreas Phantom for Ion beam Therapy (PPIeT) was irradiated with carbon ions. The phantom features a pancreas with a virtual tumour and OARs including a duodenum, kidneys, a spine and a spinal cord. Breathing-induced organ motion was imitated with amplitudes of 0 mm (control), 5 mm, 10 mm and 20 mm while irradiating with and without gating. Dose measurements were performed using an ionisation chamber and passive detectors.
The prescribed uniform dose of 1.37 Gy in the virtual tumour was experimentally validated for the control. Breathing-induced motion of 20 mm led to a 75 % dose coverage at the target improving to 91 % with gating. For the OARs, the mean dose varied according to the organ, with gating showing no significant differences.
Accurate CIRT dosimetry with variable breathing-induced motions can be conducted with PPIeT for a pancreatic tumour and the OARs. Gating mitigated the effects of breathing-induced motion in the tumour.
碳离子放射治疗（CIRT）已在胰腺癌治疗中展现出良好的治疗效果。然而，呼吸引起的器官运动可能会影响治疗效果，导致靶区及危及器官（OARs）内剂量不足或过量。在本研究中，使用人体模型在碳离子放射治疗期间同时测量靶区和OARs的剂量，以评估呼吸门控补偿呼吸运动的有效性。
使用碳离子束照射用于离子束治疗的胰腺模型（PPIeT）。该模型具有一个带有虚拟肿瘤的胰腺以及包括十二指肠、肾脏、脊柱和脊髓在内的OARs。在有门控和无门控照射时，模拟呼吸引起的器官运动，幅度分别为0毫米（对照）、5毫米、10毫米和20毫米。使用电离室和无源探测器进行剂量测量。
在对照实验中，虚拟肿瘤处规定的均匀剂量1.37 Gy得到了验证。呼吸引起的20毫米运动导致靶区剂量覆盖从75%提高到门控时的91%。对于OARs，平均剂量因器官而异，门控时无显著差异。
使用PPIeT可以对胰腺肿瘤和OARs进行具有可变呼吸引起运动的精确碳离子放射治疗剂量测定。门控减轻了肿瘤中呼吸引起运动的影响。
