title: Radiation dose reduction to breast and thyroid during MDCT: effectiveness of an in-plane bismuth shield.
abstract: 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.
authors.affiliation: Department of Diagnostic Radiology, University of Technology of Aachen, Aachen, Germany. hohl@rad.rwth-aachen.de
authors.forename: C
authors.initials: C
authors.lastname: Hohl
authors.forename: J E
authors.initials: JE
authors.lastname: Wildberger
authors.forename: C
authors.initials: C
authors.lastname: Süss
authors.forename: C
authors.initials: C
authors.lastname: Thomas
authors.forename: G
authors.initials: G
authors.lastname: Mühlenbruch
authors.forename: T
authors.initials: T
authors.lastname: Schmidt
authors.forename: D
authors.initials: D
authors.lastname: Honnef
authors.forename: R W
authors.initials: RW
authors.lastname: Günther
authors.forename: A H
authors.initials: AH
authors.lastname: Mahnken
mesh_terms: 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*
chemical_list: D001729:Bismuth