Radiation dose reduction to breast and thyroid during MDCT: effectiveness of an in-plane bismuth shield.
OBJECTIVE
To evaluate dose reduction and image deterioration using in-plane bismuth breast-shielding and thyroid-shielding for MDCT.


METHODS
Skin and organ doses of thyroid and breast were measured with thermoluminescent dosimeters in a female Alderson-Rando Phantom with and without a 4-ply in-plane bismuth shield. Routine neck (120 kVp, 150 mAs(eff); 16 x 1.5 mm) and chest (120 kVp, 100 mAs(eff); 16 x 1.5 mm) scan protocols were simulated on a 16-row MDCT scanner in three different settings: without shielding, with the shield directly on the surface, and with a 1-cm-thick cotton spacer between surface and shield. Image noise was quantified and compared using the t test.


RESULTS
On average, shielding resulted in a 47% organ-dose reduction for the thyroid and 32% for the breast. Placement of the spacer between shield and surface had no significant impact on the measured doses, but significantly decreased the image noise (P < 0.05).


CONCLUSIONS
In-plane bismuth breast and thyroid shielding significantly decreases radiation dose in MDCT without deteriorating image quality.
Hohl
C
C
Department of Diagnostic Radiology, University of Technology of Aachen, Aachen, Germany. hohl@rad.rwth-aachen.de
Wildberger
J E
JE
Süss
C
C
Thomas
C
C
Mühlenbruch
G
G
Schmidt
T
T
Honnef
D
D
Günther
R W
RW
Mahnken
A H
AH
D016477:Artifacts; D001729:Bismuth; D001940:Breast / Q000528:radiation effects*; D032561:Cotton Fiber; D004867:Equipment Design; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011835:Radiation Protection / Q000295:instrumentation* / Q000379:methods; D011856:Radiographic Image Enhancement; D012867:Skin / Q000528:radiation effects; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation; D013961:Thyroid Gland / Q000528:radiation effects*; D014057:Tomography, X-Ray Computed / Q000379:methods*
D001729:Bismuth