Digital tomosynthesis: a new technique for imaging nephrolithiasis. Specific organ doses and effective doses compared with renal stone protocol noncontrast computed tomography.
OBJECTIVE
To determine organ-specific doses (ODs) and effective dose (ED) for digital tomosynthesis (DT) and compare it with our institutional renal stone protocol noncontrast computed tomography (NCCT).


METHODS
A validated anthropomorphic male phantom was placed supine on a digital GE Definium 8000 radiological scanner. Thermoluminescent dosimeters were placed in 256 locations and used to measure OD. A routine DT study was performed consisting of 2 scout images and 1 tomographic sweep in a 14.2-degree arc over the phantom. Software is used to recreate a series of coronal images from the sweep. ODs were determined as the sum of the doses for the study. Equivalent doses were calculated by multiplying OD with the appropriate tissue weighting factor. ED is the summation of the equivalent doses. OD and ED were determined in a similar fashion (using dosimeters) for a renal stone protocol NCCT and doses were compared.


RESULTS
ODs for DT are significantly lower compared with NCCT. The ED for NCCT is 3.04 ± 0.34 mSv. The calculated ED for DT is 0.87 ± 0.15 mSv (2 scouts at 0.17 mSv and 0.14 mSv and 1 sweep at 0.56 mSv), P <.0001.


CONCLUSIONS
DT exposes patients to substantially less radiation than NCCT. This is particularly true for radiation-sensitive organs. Further studies are needed to compare the sensitivity and specificity of DT as compared with NCCT. However, its low overall radiation dose makes it an ideal study for the follow-up of recurrent stone formers in the office setting.
Division of Urologic Surgery, Duke University Medical Center, Durham, NC; Department of Urology, Universitätsmedizin Mainz, Johannes Gutenberg University, Mainz, Germany.
Andreas
A
Neisius
Department of Urology, Universidad Católica de Chile, Santiago, Chile.
Gaston M
GM
Astroza
Duke University Medical Center, Duke Radiation Dosimetry Laboratory, Durham, NC; Duke University Medical Center, Medical Physics Graduate Program, Durham, NC.
Chu
C
Wang
Duke University Medical Center, Duke Radiation Dosimetry Laboratory, Durham, NC.
Giao
G
Nguyen
Division of Urologic Surgery, Duke University Medical Center, Durham, NC.
Nicholas J
NJ
Kuntz
Duke University Medical Center, Duke Radiation Dosimetry Laboratory, Durham, NC; Duke University Medical Center, Medical Physics Graduate Program, Durham, NC.
Natalie
N
Januzis
Division of Urologic Surgery, Duke University Medical Center, Durham, NC.
Michael N
MN
Ferrandino
Duke University Medical Center, Duke Radiation Dosimetry Laboratory, Durham, NC.
Terry T
TT
Yoshizumi
Division of Urologic Surgery, Duke University Medical Center, Durham, NC.
Glenn M
GM
Preminger
Division of Urologic Surgery, Duke University Medical Center, Durham, NC. Electronic address: michael.lipkin@duke.edu.
Michael E
ME
Lipkin
D006801:Humans; D008297:Male; D053040:Nephrolithiasis / Q000000981:diagnostic imaging*; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods*