title: [Study of fast acquisition technique for heavy ion CT system based on the measurement of residual range distribution].
abstract: We proposed a new technique for the fast acquisition heavy ion CT (HICT) system based on the measurement of residual range distribution using an intensifying screen and charge coupled device camera. The previously used fast acquisition HICT system had poor electron density resolution. In the new technique, the range shifter thickness is varied over the required dynamic range in the spill of the heavy ion beam at each projection angle and the residual range distribution is determined by a series of acquisition data. We examined the image quality using the contrast noise ratio and the noise power spectrum, and estimated the electron density resolution, using a low-contrast phantom for measurement of electron density resolution. The image quality of the new technique was superior to that of the previous fast acquisition HICT system. Furthermore, the relative electron density resolution was 0.011, which represented an improvement of about 12-fold. Therefore we showed that the new technique was potentially useful in clinical use of HICT, including treatment and quality assurance of heavy ion therapy.
authors.affiliation: National Cancer Center Hospital East, Chiba, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Mogaki
authors.affiliation: Ibaraki Prefectural University of Health Sciences, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Abe
authors.affiliation: Ibaraki Prefectural University of Health Sciences, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sato
authors.affiliation: Kitasato University, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Muraishi
authors.affiliation: Kitasato University, Japan.
authors.forename: Hidetake
authors.initials: H
authors.lastname: Hara
authors.affiliation: Yamanashi Gakuin University, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hara
authors.affiliation: Tokiwa University, Japan.
authors.forename: Shoko
authors.initials: S
authors.lastname: Miyake
authors.affiliation: National Institute of Radiological Sciences, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Himukai
authors.affiliation: Gunma University, Japan.
authors.forename: Tatsuaki
authors.initials: T
authors.lastname: Kanai
mesh_terms: D004583:Electrons; D063193:Heavy Ion Radiotherapy / Q000379:methods*; D020450:Heavy Ions; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D019047:Phantoms, Imaging; D011785:Quality Assurance, Health Care; D011829:Radiation Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed / Q000379:methods*