Annual Report

41. Clinical Application of Autoactivation PET Imaging Derived From C-12 Ion Radiotherapy.

Kyosan Yoshikawa, Takehiro Tomitani, Mitsutaka Kanazawa, Tatsuaki Kanai, Masahiro Endo, Katsumi Tamura, Masahisa Koga, Hirotoshi Katoh, Susumu Kandatsu, Jun Mizoe, Hirohiko Tsujii, Katsya. Yoshida, Kazutoshi Suzuki, Fumio Shishido and Hiroshi Fukuda.

Keywords: PET, C-12 ion radiotherapy, autoactivation imaging

Clinical application of PET imaging of auto activation derived from C-12 ion radiotherapy (HIMAC) was studied. We introduced a patient fixation system for auto activation PET measurements. Using this fixation system, we can get PET images with the same patient positioning as with patient positioning of HIMAC therapy planning CT. It is very important to perform the PET measurements under exactly the same patient positioning as in HIMAC therapy to compare RI distributions.

We performed some clinical PET measurements and got superimposed images of PET and CT planning of HIMAC therapy patients. Cases in this study were malignant melanoma of the esophagus, original lung cancer, metastatic lung cancer from colon cancer, hepatocellular carcinoma, and metastatic bone tumor from thyroid cancer. We tried two fitting methods. In the first method, fitting parameters calculated from phantom simulation studies were used for modifying PET emission images in order to make superimposed images of PET and CT planning. In the second method, the automatic multi modality image registration method (AMIR method)of the Dr. View applications was used. In the latter method, we fitted the transmission images of PET to planning CT images at the start, and then superimposed emission images on the planning CT images. Our fitting results were relatively good in both methods. It seemed that the fitting results of the AMIR method had somewhat better fitting error than the phantom parameter method. We think the reason of this was insufficiency and immaturity of the measuring system for patient setup parameters on the PET bed. We are looking at ways to solve this problem.

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