title: [Development of the QA/QC-tools for CT number calibration of the treatment planning CT-scanner.].
abstract: In order to support a routine QA of the CT number for treatment planning, we developed a phantom and a sample holder for easy handling. At most particle radiotherapy facilities in Japan, the CT number is calibrated by the poly-binary calibration method using liquid samples of 100% ethanol and 40% K(2)HPO(4) which are set in a cylindrical water phantom. However it is hard to remove air bubbles from the calibration liquid sample and maintain its stable concentration for a long time. So much time is needed for QA of the CT number. The new sample holder, which we developed, was able to keep a stable concentration of the liquid for more than 300 days. Consequently, the CT number of each sample, which was set in a water equivalent solid phantom, was the same as the CT number in a water phantom within 7 HU. In addition, we developed software which could measure the CT number of each sample semi-automatically and could calculate the calibration coefficients between the CT number and water equivalent length (WEL). Using this software, we could check the calibration result instantly at the time of CT data acquisition. These tools should be useful to carry out calibration of the CT-WEL routinely in a short time.
authors.affiliation: Accelerator Engineering Corporation, 4-9-1, Anagawa, Inage-ku, Chiba 263-8555, Japan. kusano@aec-beam.co.jp.
authors.forename: Yohsuke
authors.initials: Y
authors.lastname: Kusano
authors.forename: Shinichi
authors.initials: S
authors.lastname: Minohara
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Ishii
authors.forename: Kengo
authors.initials: K
authors.lastname: Fujimori
authors.forename: Noritoshi
authors.initials: N
authors.lastname: Ikeda
authors.forename: Takanori
authors.initials: T
authors.lastname: Kondo
authors.forename: Hideo
authors.initials: H
authors.lastname: Tubuku
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ito
authors.forename: Hirohisa
authors.initials: H
authors.lastname: Uchida
mesh_terms: D002138:Calibration; D006801:Humans; D007564:Japan; D019047:Phantoms, Imaging; D011880:Radiotherapy Planning, Computer-Assisted; D015203:Reproducibility of Results; D015898:Tomography Scanners, X-Ray Computed; D014057:Tomography, X-Ray Computed