Open AccessComparison of central, peripheral, and weighted size-specific dose in CT
Author(s) -
Choirul Anam,
Dwi Adhianto,
Heri Sutanto,
Kusworo Adi,
Mohd Hanafi Ali,
William Rae,
Toshioh Fujibuchi,
Geoff Dougherty
Publication year - 2020
Publication title -
journal of x-ray science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.357
H-Index - 32
eISSN - 1095-9114
pISSN - 0895-3996
DOI - 10.3233/xst-200667
Subject(s) - imaging phantom , water equivalent , nuclear medicine , ionization chamber , pencil (optics) , materials science , scanner , peripheral , homogeneous , biomedical engineering , medicine , ionization , physics , optics , ion , quantum mechanics , meteorology , snow , thermodynamics
The objective of this study is to determine X-ray dose distribution and the correlation between central, peripheral and weighted-centre peripheral doses for various phantom sizes and tube voltages in computed tomography (CT). We used phantoms developed in-house, with various water-equivalent diameters (Dw) from 8.5 up to 42.1 cm. The phantoms have one hole in the centre and four holes at the periphery. By using these five holes, it is possible to measure the size-specific central dose (Ds,c), peripheral dose (Ds,p), and weighted dose (Ds,w).The phantoms are scanned using a CT scanner (Siemens Somatom Definition AS), with the tube voltage varied from 80 up to 140 kVps. The doses are measured using a pencil ionization chamber (Ray safe X2 CT Sensor) in every hole for all phantoms. The relationships between Ds,c, Ds,p, and Ds,w, and the water-equivalent diameter are established. The size-conversion factors are calculated. Comparisons between Ds,c, Ds,p, and Ds,ware also established. We observe that the dose is relatively homogeneous over the phantom for water-equivalent diameters of 12-14 cm. For water-equivalent diameters less than 12 cm, the dose in the centre is higher than at the periphery, whereas for water-equivalent diameters greater than 14 cm, the dose at the centre is lower than that at the periphery. We also find that the distribution of the doses is influenced by the tube voltage. These dose distributions may be useful for calculating organ doses for specific patients using their CT images in future clinical practice.