[New method of estimating effective energy for X-ray CT scanners].
Because the exposure dose in X-ray computed tomography examinations is sometimes difficult to determine, it is important to be able to estimate the dose for these examinations. The effective energy of the X-ray CT scanner is required to estimate exposure dose. Although the half-value-layer (HVL) method has been used to calculate effective energy, it is not an easy method. This paper proposes a technique by which effective energy can be easily calculated. Certain details were found to cause change in effective energy, and the ratio (inner-metal center-air ratio: IMCAR) between air dose and dose in fixing the metallic pipe in the isocenter of an X-ray CT scanner was necessary. The IMCAR from a different X-ray CT scanner was required, and, when effective energy was calculated, it showed an error of less than 0.7% for the half-value-layer method. The effect of this error on dose estimation was slight (0.4%). This technique is useful, because effective energy can easily be calculated with a high degree of accuracy.
Nagashima
Hiroyuki
H
Department of Clinical Radiology, Gunma Prefectural College of Health Sciences.
Sunaga
Shinichi
S
Mitome
Toyohisa
T
Koya
Eiichi
E
Takei
Hiroyuki
H
Matsubara
Kunio
K
Ogura
Toshihiro
T
Shiraishi
Akihisa
A
Shimosegawa
Masayuki
M
Hoshina
Masao
M
Igarashi
Hitoshi
H
D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*