Dose reduction during CT fluoroscopy: phantom study of angular beam modulation.
OBJECTIVE
To prospectively evaluate, in a phantom, the dose reductions achievable by using angular beam modulation (ABM) during computed tomographic (CT) fluoroscopy-guided thoracic interventions.


METHODS
To enable measurement of organ doses and effective patient dose, a female Alderson-Rando phantom was equipped with thermoluminescent dosimeters (TLDs) in 41 positions, with three TLDs in each position. Additionally, the local dose was assessed in 22 locations above the phantom to estimate the radiation exposure to the radiologist's hand and the patient's skin dose during thoracic interventions. Radiation exposure was performed with a 64-section multidetector CT scanner in the CT fluoroscopy mode, simulating a CT fluoroscopy-guided chest intervention. Effective dose, breast dose, and the dose to the radiologist's hand during the simulated chest intervention were measured with and without ABM. Image noise as an indicator for image quality was compared for both settings. Statistical significance of the measured dose reductions and the image noise was tested by using the paired-samples t test, with P < .05 indicating a significant difference.


RESULTS
ABM significantly reduced the effective patient dose by 35%, the skin dose by 75%, the breast dose by 47% (P < .001 for all), and the physician's hand dose by between 27% (scattered radiation, P = .007) and 72% (direct radiation, P < .001). No significant difference was found in a comparison of the image noise with and that without ABM.


CONCLUSIONS
ABM leads to significant dose reductions for both patients and personnel during CT fluoroscopy-guided thoracic interventions, without impairing image quality.
Hohl
Christian
C
Department of Diagnostic Radiology, University of Technology of Aachen, Pauwelsstrasse 30, D-52057 Aachen, Germany. hohl@rad.rwth-aachen.de
Suess
Christoph
C
Wildberger
Joachim E
JE
Honnef
Dagmar
D
Das
Marco
M
Mühlenbruch
Georg
G
Schaller
Andreas
A
Günther
Rolf W
RW
Mahnken
Andreas H
AH
D000328:Adult; D001822:Body Burden; D005260:Female; D005471:Fluoroscopy / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D015641:Radiography, Interventional / Q000295:instrumentation / Q000379:methods*; D013902:Radiography, Thoracic / Q000295:instrumentation / Q000379:methods*; D011874:Radiometry / Q000379:methods*; D012062:Relative Biological Effectiveness; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*