Radiation dose savings for adult pulmonary embolus 64-MDCT using bismuth breast shields, lower peak kilovoltage, and automatic tube current modulation.
OBJECTIVE
The purpose of this study was to assess whether radiation dose savings using a lower peak kilovoltage (kVp) setting, bismuth breast shields, and automatic tube current modulation could be achieved while preserving the image quality of MDCT scans obtained to assess for pulmonary embolus (PE).


METHODS
CT angiography (CTA) examinations were performed to assess for the presence or absence of pulmonary artery emboli using a 64-MDCT scanner with automatic tube current modulation (noise level=10 HU), two kVp settings (120 and 140 kVp), and bismuth breast shields. Absorbed organ doses were measured using anthropomorphic phantoms and metal oxide semiconductor field effect transistor (MOSFET) detectors. Image quality was assessed quantitatively as well as qualitatively in various anatomic sites of the thorax.


RESULTS
Using a lower kVp (120 vs 140 kVp) and automatic tube current modulation resulted in a dose savings of 27% to the breast and 47% to the lungs. The use of a lower kVp (120 kVp), automatic tube current modulation, and bismuth shields placed directly on the anterior chest wall reduced absorbed breast and lung doses by 55% and 45%, respectively. Qualitative assessment of the images showed no change in image quality of the lungs and mediastinum when using a lower kVp, bismuth shields, or both.


CONCLUSIONS
The use of bismuth breast shields together with a lower kVp and automatic tube current modulation will reduce the absorbed radiation dose to the breast and lungs without degradation of image quality to the organs of the thorax for CTA detection of PE.
Hurwitz
Lynne M
LM
Department of Radiology, Duke University Medical Center, Box 3808, Durham, NC 27710, USA.
Yoshizumi
Terry T
TT
Goodman
Philip C
PC
Nelson
Rendon C
RC
Toncheva
Greta
G
Nguyen
Giao B
GB
Lowry
Carolyn
C
Anderson-Evans
Colin
C
D000328:Adult; D001822:Body Burden; D005260:Female; D006801:Humans; D008297:Male; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D011829:Radiation Dosage; D011835:Radiation Protection / Q000295:instrumentation* / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D012062:Relative Biological Effectiveness; D014057:Tomography, X-Ray Computed / Q000295:instrumentation* / Q000379:methods*