Use of a Gadolinium Filter on an X-ray Contrast Examination

The use of gadolinium (Gd) as a “band pass” filter for the X-ray contrast examination is discussed. Vinyl tubes filled with iodine solution were placed in a water phantom (15 cm thickness). When this phantom was exposed to a 70 kVp X-ray filtered by a Gd-filter, to give an equal film density as an aluminium (Al) filter, the surface dose was reduced by 45 % . The effective attenuation coefficient of the iodine for an 80 kVp X-ray filtered with a Gdfilter of 0.4 mm thickness corresponds to that for a 70 kVp X-ray filtered with an Al-filter of 2 mm thickness. These results indicate that a decrease of skin dosage and an increase of film contrast are obtained by using a Gd-filter for the X-ray examination with an iodine contrast medium.