Breast dose reduction for chest CT by modifying the scanning parameters based on the pre-scan size-specific dose estimate (SSDE)
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To investigate the usefulness of modifying scanning parameters based on the size-specific dose estimate (SSDE) for a breast-dose reduction for chest CT.
Materials and methods
We scanned 26 women with a fixed volume CT dose index (CTDIvol) (15 mGy) and another 26 with a fixed SSDE (15 mGy) protocol (protocol 1 and 2, respectively). In protocol 2, tube current was calculated based on the patient habitus obtained on scout images. We compared the mean breast dose and the inter-patient breast dose variability and performed linear regression analysis of the breast dose and the body mass index (BMI) of the two protocols.
The mean breast dose was about 35 % lower under protocol 2 than protocol 1 (10.9 mGy vs. 16.8 mGy, p < 0.01). The inter-patient breast dose variability was significantly lower under protocol 2 than 1 (1.2 mGy vs. 2.5 mGy, p < 0.01). We observed a moderate negative correlation between the breast dose and the BMI under protocol 1 (r = 0.43, p < 0.01); there was no significant correlation (r = 0.06, p = 0.35) under protocol 2.
The SSDE-based protocol achieved a reduction in breast dose and in inter-patient breast dose variability.
• CT scan parameters can be modified based on the pre-scan SSDE.
• The pre-scan SSDE is useful for a breast dose reduction.
• The fixed SSDE protocol reduced individual variations in the breast dose.
KeywordsChest CT Breast radiation dose SSDE CTDIvol MOSFET
Adaptive iterative dose reduction
Body mass index
Volume CT dose index
Dose length product
Metal oxide semiconductor field effect transistor
Region of interest
Size-specific dose estimate
We thank Akira Taniguchi and Takashi Tsutsumi (Centre for Medical Research and Development, Toshiba Medical Systems Corporation) for valuable technical comments. The scientific guarantor of this publication is Yasuyuki Yamashita. The authors of this manuscript declare no relationships with any companies whose products or services may be related to the subject matter of the article. The authors state that this work has not received any funding. No complex statistical methods were necessary for this paper. Institutional Review Board approval was obtained. Written informed consent was obtained from all subjects (patients) in this study. None of our study subjects or cohorts have been previously reported. Methodology: Prospective, case–control study, performed at one institution.
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