Medical application of radioactive nuclear beams at HIMAC

Abstract

The position of a short-lived positron emitting nuclei, such as 10 C and 11 C, can be precisely detected by measuring annihilation gamma-rays. By using the radioactive nuclear beam (RNB) of such nuclei, a particle range and an irradiated area can be observed in the human body. In order to improve the heavy ion cancer therapy, the RNB verification system has been developed at National Institute of Radiological Sciences (NIRS). The RNB has been obtained by the projectile fragmentation method from the relativistic high-energy heavy ion beams from the Heavy Ion Medical Accelerator in Chiba (HIMAC). The RNB system consists of a secondary beam course, a beam irradiation system, a patient's positioning system, and annihilation gamma-rays detectors.We measured the precise range by the positron camera detector and observed 3-D irradiate areas as PET images. Details of the system have been reported [1, 2].The instrumental accuracy obtained by experiments using the plastic phantom satisfied the requirement. However, the study of the biological and chemical process of the metabolism is important for the medical application. We determined the lifetime of the 10 C and 11 C injected into different organs of alive and dead rabbits. The lifetime in the alive rabbit has at least three components. These components are due to the very fast blood-stream in the blood vessel, the regional blood flow in the tissue, and unknown products which had the slow diffusion speed. In addition, The lifetimes for brains are faster than the muscle's ones.The microscopic process around the cell is also interested to study the biological effectiveness. The experiment of 9 C and 8 B beam is utilized for the research of the multi-hit cell. Because of the incident 8 B produces 8 Be, and then it emits two alpha particles. The range of these alpha particles in the water is about 10μm and it is equivalent as the size of normal cell. It means the cell is hit by three charged particles at the same time. We obtained the difference between 9 C and 12 C.[1] M. Kanazawa et al., Nucl. Phys. A 746, 393c (2004).[2] Y. Iseki et al., Phys. Med. Biol. 49, 1 (2004).

Experimental validation of the FLUKA Monte Carlo code for dose and $\beta^+$ -emitter predictions of radioactive ion beams

“…Circa 1% of primary beam can be transformed into radioactive ion beams (Iseki et al 2004) by means of a secondary beam line. Some RIβ + attain intensities sufficiently high for PET tests, Treatment Planning verification and even match treatment clinical standards (Kitagawa et al 2006, Mohammadi et al 2016.…”

“…Moreover, due to the low reaction yields the beam rate is substantially low. On the other hand, the purity levels can be considerably high, typically over 90% (Kitagawa et al 2006), with the remaining percentage consisting of species with the same magnetic rigidity of the secondary beam produced via projectile fragmentation in the production target denoted in figure 4. Usage of RIβ + is expected to boost in beam PET acquisitions, due to the projectile's radioactive nature but also other short-lived β + emitters (e.g.…”

Review on heavy ion radiotherapy facilities and related ion sources (invited)

“…RIBs are still being researched, 19 and they have not been utilized for clinical trials. QCBs were demonstrated, however they are not necessary now.…”

Recent developments of ion sources for life-science studies at the Heavy Ion Medical Accelerator in Chiba (invited)

“…87, 02C107 (2016) the other hand, the needs for specified isotopes are very rare for the biology users, as compared with those of the nuclearphysics users, except for medical applications of radioactive nuclear beams. 9 Most biology experiments require a uniform irradiation field at cell samples or animals. The necessary beam intensity depends on the field size, the beam energy, and the efficiency of an irradiation method.…”