Organ-based dose current modulation and thyroid shields: techniques of radiation dose reduction for neck CT.

Published

Journal Article

OBJECTIVE: The purpose of this study was to assess the difference in absorbed organ dose and image quality for MDCT neck protocols using automatic tube current modulation alone compared with organ-based dose modulation and in-plane thyroid bismuth shielding. MATERIALS AND METHODS: An anthropomorphic female phantom with metal oxide semiconductor field effect transistor (MOSFET) detectors was scanned on a 64-MDCT scanner. The protocols included a reference neck CT protocol using automatic tube current modulation and three modified protocols: organ-based dose modulation, automatic tube current modulation with thyroid shield, and organ-based dose modulation with thyroid shield. Image noise was evaluated quantitatively with the SD of the attenuation value, and subjectively by two neuroradiologists. RESULTS: Organ-based dose modulation, automatic tube current modulation with thyroid shield, and organ-based dose modulation with thyroid shield protocols reduced the thyroid dose by 28%, 33%, and 45%, respectively, compared with the use of automatic tube current modulation alone (p ≤ 0.005). Organ-based dose modulation also reduced the radiation dose to the ocular lens (33-47%) compared with the use of automatic tube current modulation (p ≤ 0.04). There was no significant difference in measured noise and subjective image quality between the protocols. CONCLUSION: Both organ-based dose modulation and thyroid shields significantly reduce the thyroid organ dose without degradation of subjective image quality compared with automatic tube current modulation. Organ-based dose modulation has the additional benefit of dose reduction to the ocular lens.

Full Text

Duke Authors

Cited Authors

  • Hoang, JK; Yoshizumi, TT; Choudhury, KR; Nguyen, GB; Toncheva, G; Gafton, AR; Eastwood, JD; Lowry, C; Hurwitz, LM

Published Date

  • May 2012

Published In

Volume / Issue

  • 198 / 5

Start / End Page

  • 1132 - 1138

PubMed ID

  • 22528904

Pubmed Central ID

  • 22528904

Electronic International Standard Serial Number (EISSN)

  • 1546-3141

International Standard Serial Number (ISSN)

  • 0361-803X

Digital Object Identifier (DOI)

  • 10.2214/ajr.11.7445

Language

  • eng