Katsushi Hanawa

Spot Scanning Using Radioactive 11C Beams for Heavy-Ion Radiotherapy

A scheme for spot scanning using 11C beams has been developed in order to form and verify a three-dimensionally conformal irradiation field for cancer radiotherapy. By selecting the momentum spread of a 11C beam, we could considerably decrease the distal falloff of the irradiation field, thus conserving the beam quality. To estimate and optimize the dose distribution in the irradiation field, it is essential to evaluate the precise dose distribution of spot beams. The coupling of the lateral dose and depth-dose distributions originating from a wide momentum spread should be taken into account to calculate the dose distribution of 11C beams. The reconstructed dose distribution of the irradiation field was in good agreement with the experimental results, i.e., within ±0.2%. An irradiation field of 35×35×43 mm3 was optimized and spot scanning using 11C beams was carried out. The flatness was within ±2.3% with an error of 1% in the detector resolution.

Medical application of radioactive nuclear beams at HIMAC

By using the radioactive nuclear beam with relativistic high energy of short-lived positron emitting nuclei, such as C10 and C11, a verification system for the precise radiotherapy has been developed. It is possible to determine the precise particle range and the three-dimensional irradiated area in the human body by a positron camera detector and a positron emission tomography system, respectively. The biological and chemical process of the metabolism is an important parameter for the precise measurement. The biological lifetimes of the C10 and C11 injected into the rabbit’s organs have been observed for the study of metabolism. The microscopic process around the cell is also of interest in the study of biological effectiveness. The observation of the difference between radiological effectiveness of C9 and that of C12 is in progress.By using the radioactive nuclear beam with relativistic high energy of short-lived positron emitting nuclei, such as C10 and C11, a verification system for the precise radiotherapy has been developed. It is possible to determine the precise particle range and the three-dimensional irradiated area in the human body by a positron camera detector and a positron emission tomography system, respectively. The biological and chemical process of the metabolism is an important parameter for the precise measurement. The biological lifetimes of the C10 and C11 injected into the rabbit’s organs have been observed for the study of metabolism. The microscopic process around the cell is also of interest in the study of biological effectiveness. The observation of the difference between radiological effectiveness of C9 and that of C12 is in progress.