Radiation dose reduction to breast and thyroid during MDCT: effectiveness of an in-plane bismuth shield

Acta Radiol. 2006 Jul;47(6):562-7. doi: 10.1080/02841850600702150.


Purpose: To evaluate dose reduction and image deterioration using in-plane bismuth breast-shielding and thyroid-shielding for MDCT.

Material and 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).

Conclusion: In-plane bismuth breast and thyroid shielding significantly decreases radiation dose in MDCT without deteriorating image quality.

Publication types

  • Comparative Study

MeSH terms

  • Artifacts
  • Bismuth*
  • Breast / radiation effects*
  • Cotton Fiber
  • Equipment Design
  • Female
  • Humans
  • Image Processing, Computer-Assisted / methods*
  • Phantoms, Imaging
  • Radiation Dosage*
  • Radiation Protection / instrumentation*
  • Radiation Protection / methods
  • Radiographic Image Enhancement
  • Skin / radiation effects
  • Thermoluminescent Dosimetry / instrumentation
  • Thyroid Gland / radiation effects*
  • Tomography, X-Ray Computed / methods*


  • Bismuth