B. Hansson et al., ADDED COPPER FILTRATION IN DIGITAL PEDIATRIC DOUBLE-CONTRAST COLON EXAMINATIONS - EFFECTS ON RADIATION-DOSE AND IMAGE QUALITY, European radiology, 7(7), 1997, pp. 1117-1122
Paediatric double-contrast barium enema examinations are usually perfo
rmed at high tube voltage, 102-105 kV. The aim of this study was to in
vestigate how much the effective dose to the child could be reduced by
increasing the X-ray energy further by adding copper filter in the be
am, and if this dose reduction could be achieved without endangering i
mage quality. Organ doses to an anthropomorphic phantom simulating a 1
-year-old child was measured using thermoluminescence dosimetry for as
sessment of the effective dose and this value was compared with the en
ergy imparted which was obtained from kerma-area product measurements.
To verify that the image quality achieved with this added filtration
was still diagnostically acceptable, the study included 15 patient exa
minations. Since the increased X-ray energy will most probably affect
low-contrast objects, image quality was also evaluated with two differ
ent phantoms containing low-contrast objects. Effective dose for a com
plete examination can be decreased 44 % and energy imparted 77 % when
a 0.3-mm cop,per filter is inserted in the beam at tube voltage 102 kV
. The patient study did not show any significant deterioration of imag
e quality, whereas phantom mea surements of contrast-detail resolution
and signal-to-noise ratio was marginally impaired by the added copper
filtration. This technique is now in clinical practice for paediatric
colon examinations.