Conor Patrick Shortt MBBCH, Presenter: Nothing to Disclose

Noel Fanning, Abstract Co-Author: Nothing to Disclose

Leslie Malone, Abstract Co-Author: Nothing to Disclose

Paul Brennan, Abstract Co-Author: Nothing to Disclose

Michael James Lee MD, Abstract Co-Author: Nothing to Disclose

We measured radiation doses to the eye and thyroid during diagnostic cerebral angiography to assess the effectiveness of bismuth and lead shields at dose reduction.

Two phantom head angiographic studies were performed. In study 1(12 phantoms), commercially available bismuth shields(Pb eq.=0.06mm) were used. Eight thermoluminescent dosimeters(TLDs) were placed in constant positions over the eyes(4 TLDs) and thyroid(4 TLDS) in three groups: A)No shields(n=4) B)Anterior bismuth shields(n=4) C)Anterior and posterior bismuth shields(n=4). In study 2 (8 phantoms) lead shields(Pb eq.= 0.5mm.) were placed over the thyroid only and TLD dose measurements obtained in 2 groups: A) No shielding(n=4) and B) Thyroid lead shielding(n= 4). A standard 4 vessel cerebral angiogram was performed on each phantom with a GE fluoroscopy system.

Study 1(bismuth shields) demonstrated higher doses to the eyes compared to thyroid(mean 13.03 vs. 5.98 mSv, p<0.001), and a higher eye dose on the x-ray tube side(right eye vs. left eye: 16.08 vs. 9.98 mSv, p=0.02; right thyroid vs. left thyroid: 6.51 vs 5.46 mSv, p=0.487).Overall, the use of bismuth shielding did not significantly reduce dose to either eyes or thyroid in the measured TLD positions. In study 2(thyroid lead shields) a significant dose reduction was found in 3/4 TLD positions over the thyroid in the shielded group compared to the unshielded group with an overall mean thyroid dose reduction of 47% (mean 2.46 vs. 4.62 mSv, p<0.001).

Considerable radiation doses to the radiosensitive eyes and thyroid highlight the need for increased awareness of patient radiation protection. The eyes and tube side of patient incur higher doses. Eye shielding is impractical as it interferes with diagnostic capabilities. Thyroid lead shielding in diagnostic cerebral angiography yields significant protection to the thyroid, is not in the field of view and should be used routinely. A patient study is underway.

Shortt, C, Fanning, N, Malone, L, Brennan, P, Lee, M, Radiation Protection to the Eye and Thyroid during Diagnostic Cerebral Angiography: A Phantom Study.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4409561.html