49. Clinical Application of Autoactivatmon PET Imaging Derived from C-12 Ion Radiotherapy

Kyosan Yoshikawa, Takehiro Tomitant, Mitsutaka Kanazawa, Tatsuaki Kanan, Masahiro Endo, Katsumt Tamura, Masahisa Koga, Hirotoshi Katoh, Susumu Kandatsu, Junetsu Mizoe, Hirotoshi Tsujii, Katsuya Yoshida, Kazutoshi Suzuki, Fumio Shishido and Hiroshi Fukuda.

Keywords: positron emission tomography, C-12 ion radiotherapy, autoacttvatton imaging

Clinical application of PET imaging of autoactivation derived from C-12 ion radiotherapy was studied. We introduced the patient fixation system for auto activation PET measurements. Using this fixation system, we can get PET images with the same pattent positioning as with patient positioning of HIMAC therapy planning CT. It is very important to perform the PET measurements under exactly same patuent positioning as HIMAC therapy to compare Rl distributions. We performed a phantom simulation study to get parameters for making superimposed images of PET and CT planning. We used two phantoms, one was a cylinder phantom which contains ⁶⁸Ge-⁶⁸Ga Rl sources, i.e. a hot phantom and the other was a cylinder phantom which contains water, i.e. a cool phantom. The two phantoms were the same size and shape. We carried out therapy planning for this cool phantom in the same manner as usually used for pa tient treatment. CT planning was obtained using cool phantom. For PET measurements, the hot phantom was used. We got two sets of image data, PET tm ages and planning CT images. We discussed adjust ment of (a) the base line of the two image sets, (b) the amount of the slice gap, (c) the size of images in the X-Y plane, and (d) the position of each slice in the Z axis. We have gotten basic data for clinical applications from this simulation study.