Evaluation of dose distribution according to patient setup errors in pediatric head CT examination: A phantom study

Rumi Gotanda, Yoshihiro Takeda, Tatsuhiro Gotanda, Kosuke Ota, Takuya Akagawa, Akihiko Tabuchi, Tadao Kuwano, Hidetoshi Yatake, Koichi Yabunaka, Hitoshi Sato, Toshizo Katsuda

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Citations (Scopus)

Abstract

Radiation doses during computed tomography (CT) examinations are generally evaluated by CT dose index (CTDI). The CTDI is measured by means of a CTDI phantom, which is placed in the center of the CT gantry aperture. However, patients are not always positioned in the centered in clinical settings. In this study, dose distributions associated with patient setup errors and head size were evaluated using phantoms developed for pediatric patients. The phantoms were made using flexible acrylic sheets in a cylindrical shape [diameters of 6 (premature baby), 8 (neonate), 10 (infant), and 12 cm (child)] and placed on the end of the CT bed. The bed position was lowered from the center by up to a radius length for each phantom size. Dose distributions in the phantoms were measured using radiochromic film. By lowering the bed position, the surface doses at 0° increased and those at 180° and the center doses decreased. However, the other measurement positions exhibited complex changes depending on the phantom size. In addition, the shapes of the dose profile curves varied according to the distance from the X-ray tube (i.e. location in the gantry aperture). In this study, the surface doses became smaller with decreasing distance from the X-ray tube. Therefore, decreasing the distance from the lens to the X-ray tube would be an effective way to reduce the absorbed dose of the lens. However, the dose distributions in the phantoms varied in a complex manner depending on patient setup errors and phantom size. In addition, beam slice width and pitch were important factors in determining the amount of the CT dose. To keep radiation doses during CT examination as low as reasonably achievable, it is important to clarify the influence of CT scanning settings on CT dose.

Original languageEnglish
Title of host publication6th European Conference of the International Federation for Medical and Biological Engineering - MBEC 2014
PublisherSpringer Verlag
Pages224-227
Number of pages4
Volume45
ISBN (Print)9783319111278
DOIs
Publication statusPublished - 2015
Event6th European Conference of the International Federation for Medical and Biological Engineering, MBEC 2014 - Dubrovnik, Croatia
Duration: Sep 7 2014Sep 11 2014

Other

Other6th European Conference of the International Federation for Medical and Biological Engineering, MBEC 2014
CountryCroatia
CityDubrovnik
Period9/7/149/11/14

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Keywords

  • Computed tomography
  • Pediatric
  • Phantom
  • Radiation dosimetry
  • Radiochromic film

ASJC Scopus subject areas

  • Biomedical Engineering
  • Bioengineering

Cite this

Gotanda, R., Takeda, Y., Gotanda, T., Ota, K., Akagawa, T., Tabuchi, A., Kuwano, T., Yatake, H., Yabunaka, K., Sato, H., & Katsuda, T. (2015). Evaluation of dose distribution according to patient setup errors in pediatric head CT examination: A phantom study. In 6th European Conference of the International Federation for Medical and Biological Engineering - MBEC 2014 (Vol. 45, pp. 224-227). Springer Verlag. https://doi.org/10.1007/978-3-319-11128-5_56