Improved dose compensation model owing to short irradiation interruption time for hypoxic tumor using a microdosimetric kinetic model.

IF 1.2 Q4 ONCOLOGY Reports of Practical Oncology and Radiotherapy Pub Date : 2024-07-22 eCollection Date: 2024-01-01 DOI:10.5603/rpor.101098

Daisuke Kawahara

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Abstract

Background: The objective was to enhance the biological compensation factor related to irradiation interruption in a short time (short irradiation interruption) in hypoxic tumors using a refined microdosimetric kinetic model (MKM) for photon radiation therapy.

Materials and methods: The biological dose differences were calculated for CHO-K1 cells exposed to a photon beam, considering interruptions of (τ) of 0-120 min and pO₂ at oxygen levels of 0.075-160 mm Hg. The interrupted dose fraction (IDF) was defined as the percentage ratio of the dose delivered before short irradiation interruption to the total dose, which ranged from 10-90%. The compensated dose was calculated based on an IDF of 10-90% for a dose of 2-8 Gy and oxygen levels of 0.075-160 mm Hg.

Results: The Δ with and without short irradiation interruption was more pronounced with a higher dose and increased pO₂. It exceeded 3% between IDF of 50% and either 10% or 90% and occurred more than τ = 50 min at 0.075 mm Hg, τ = 20 min at 3 mm Hg, τ = 20 min at 8 mm Hg, τ = 20 min at 15 mm Hg, τ = 20 min at 38 mm Hg, and τ = 20 min at 160 mm Hg. The dose compensation factor was greater at higher IDF rates.

Conclusion: The biological dose decreased with longer interruption times and higher oxygen concentrations. The improved model can compensate for the biological doses at various oxygen concentrations.

Advances in knowledge: The current study improved the dose compensation method for the decrease in the biological effect owing to short irradiation interruption by considering the oxygen concentration.

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利用微剂量测定动力学模型改进缺氧肿瘤的剂量补偿模型，缩短辐照中断时间。

研究背景目的是利用光子放射治疗的微剂量测定动力学模型（MKM），在短时间内（短照射中断）提高缺氧肿瘤中与照射中断相关的生物补偿因子：计算了接受光子束照射的 CHO-K1 细胞的生物剂量差异，考虑了 0-120 分钟的中断时间（τ）和 0.075-160 mm Hg 的氧水平 pO2。中断剂量分数（IDF）的定义是短时间辐照中断前的剂量占总剂量的百分比，范围在10%-90%之间。补偿剂量是根据剂量为2-8 Gy、氧水平为0.075-160 mm Hg时的IDF为10-90%计算得出的：结果：剂量越大、血氧饱和度越高，短时间中断照射和不中断照射时的Δ越明显。在 IDF 为 50%、10% 或 90% 之间，Δ超过了 3%，在 0.075 mm Hg 时，τ = 50 分钟；在 3 mm Hg 时，τ = 20 分钟；在 8 mm Hg 时，τ = 20 分钟；在 15 mm Hg 时，τ = 20 分钟；在 38 mm Hg 时，τ = 20 分钟；在 160 mm Hg 时，τ = 20 分钟。IDF率越高，剂量补偿系数越大：结论：中断时间越长、氧气浓度越高，生物剂量越小。改进后的模型可以补偿不同氧气浓度下的生物剂量：本研究通过考虑氧气浓度，改进了辐照短时间中断导致生物效应下降的剂量补偿方法。

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来源期刊

Reports of Practical Oncology and Radiotherapy Multiple-

CiteScore

2.80

自引率

8.30%

发文量

115

审稿时长

16 weeks

期刊介绍： Reports of Practical Oncology and Radiotherapy is an interdisciplinary bimonthly journal, publishing original contributions in clinical oncology and radiotherapy, as well as in radiotherapy physics, techniques and radiotherapy equipment. Reports of Practical Oncology and Radiotherapy is a journal of the Polish Society of Radiation Oncology, the Czech Society of Radiation Oncology, the Hungarian Society for Radiation Oncology, the Slovenian Society for Radiotherapy and Oncology, the Polish Study Group of Head and Neck Cancer, the Guild of Bulgarian Radiotherapists and the Greater Poland Cancer Centre, affiliated with the Spanish Society of Radiotherapy and Oncology, the Italian Association of Radiotherapy and the Portuguese Society of Radiotherapy - Oncology.