[18a-D62-1~6] 2.4 Medical application

10:45 AM - 11:00 AM JST(1:45 AM - 2:00 AM UTC)

[18a-D62-4] Feasibility of tumor diagnosis by means of range-verification PET in carbon-ion therapy: A rat demonstration

〇Chie Toramatsu¹, Hideaki Tashima¹, Hidekatsu Wakizaka¹, Hitomi Suto¹, Chie Seki¹, Yoko Ikoma¹, Iwao Kanno¹, Taiga Yamaya¹ (1.National Institutes for Quantum Science and Technology)

Keywords:

particle therapy,PET,tumor diagnosis

In carbon ion therapy, tumor hypoxia imaging is required to optimize treatment plans for frequently changing tumor conditions, but it is impractical to execute hypoxia PET for every treatment fraction. Therefore, our idea is to use range-verification PET for tumor diagnosis. The range-verification PET visualizes positron emitters produced through nuclear fragmentation reactions in the patient body, and we expect that the biological washout speed of such positron emitters will reflect the tumor vascular conditions. In this work, we aimed at demonstrating the feasibility of this concept in a tumor model rat. Glioma cells were injected into the thigh of a rat. Two weeks later, magnetic resonance angiography (MRA) was performed as the standard of truth to determine the intratumoral vascular conditions. Then, the rat tumor was irradiated using the ¹²C beam (~8 Gy) in the Heavy Ion Medical Accelerator in Chiba (HIMAC). Immediately after the irradiation, range-verification PET was performed by using our original total-body small-animal PET system. In the range-verification PET measured for 10 min (Figure. 1-a, b). Figure 2-a shows the obtained PET image (10 min summed image), and heterogenous intensity region was observed in irradiated target tumor tissue. Difference in washout speed was clearly observed (Figure .2-b), and a high activity region corresponded to a poorly vascularized region in the MRA image. Different time activity curves were obtained depending on the high and low activity regions, which supported the feasibility of the use of range-verification PET for tumor diagnosis