Measurement of biological washout rates depending on tumor vascular status in 15O in-beam rat-PET. (21st June 2022)

• Record Type: Journal Article
• Authors: Toramatsu, Chie; Mohammadi, Akram; Wakizaka, Hidekatsu; Sudo, Hitomi; Nitta, Nobuhiro; Seki, Chie; Kanno, Iwao; Takahashi, Miwako; Karasawa, Kumiko; Hirano, Yoshiyuki; Yamaya, Taiga
• Is Part Of: Physics in medicine & biology. Volume 67:Number 12(2022)
• Publication Date: 2022-06-21
• Subjects: in-beam PET -- particle therapy -- adaptive therapy -- biological washout effect; Biophysics -- Periodicals; Medical physics -- Periodicals; 610.153
• DOI: 10.1088/1361-6560/ac72f3
• Languages: English
• ISSNs: 0031-9155

Abstract

Abstract: Objective. The biological washout of positron emitters should be modeled and corrected in order to achieve quantitative dose range verification in charged particle therapy based on positron emission tomography (PET). This biological washout effect is affected by physiological environmental conditions such as blood perfusion and metabolism, but the correlation to tumour pathology has not been studied yet. Approach. The aim of this study was to investigate the dependence of the biological washout rate on tumour vascular status in rat irradiation. Two types of tumour vascularity conditions, perfused and hypoxic, were modelled with nude rats. The rats were irradiated by a radioactive 15 O ion beam and time activity curves were acquired by dynamic in-beam PET measurement. Tumour tissue sections were obtained to observe the histology as well. The biological washout rate was derived using a single-compartment model with two decay components (medium decay, k 2 m and slow decay, k 2 s ). Main results. All k 2 m values in the vascular perfused tumour tissue were higher than the values of the normal tissue. All k 2 m values in the hypoxic tumour tissue were much lower than the values of the vascular perfused tumour tissue and slightly lower than the values of the normal tissue. Significance. The dependency of the biological washout on the tumour vasculature conditions was experimentally shown.