Pulmonary Nodule Volumetry at Different Low Computed Tomography Radiation Dose Levels With Hybrid and Model-Based Iterative Reconstruction: A Within Patient Analysis.
OBJECTIVE
The aim of the study was to determine the effects of dose reduction and iterative reconstruction (IR) on pulmonary nodule volumetry.


METHODS
In this prospective study, 25 patients scheduled for follow-up of pulmonary nodules were included. Computed tomography acquisitions were acquired at 4 dose levels with a median of 2.1, 1.2, 0.8, and 0.6 mSv. Data were reconstructed with filtered back projection (FBP), hybrid IR, and model-based IR. Volumetry was performed using semiautomatic software.


RESULTS
At the highest dose level, more than 91% (34/37) of the nodules could be segmented, and at the lowest dose level, this was more than 83%. Thirty-three nodules were included for further analysis. Filtered back projection and hybrid IR did not lead to significant differences, whereas model-based IR resulted in lower volume measurements with a maximum difference of -11% compared with FBP at routine dose.


CONCLUSIONS
Pulmonary nodule volumetry can be accurately performed at a submillisievert dose with both FBP and hybrid IR.
From the Departments of *Radiology and †Respiratory Medicine, University Medical Center, Utrecht; and ‡Department of Radiology, Erasmus Medical Center, Rotterdam, The Netherlands.
Annemarie M
AM
den Harder
Martin J
MJ
Willemink
Robbert W
RW
van Hamersvelt
Evertjan P A
EP
Vonken
Arnold M R
AM
Schilham
Jan-Willem J
JW
Lammers
Bart
B
Luijk
Ricardo P J
RP
Budde
Tim
T
Leiner
Pim A
PA
de Jong
D000368:Aged; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D015233:Models, Statistical; D011829:Radiation Dosage; D000069079:Radiation Exposure / Q000032:analysis* / Q000517:prevention & control*; D011835:Radiation Protection / Q000379:methods; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D047368:Tumor Burden