Dose reduction in computed tomography of the chest: image quality of iterative reconstructions at a 50% radiation dose compared to filtered back projection at a 100% radiation dose.
OBJECTIVE
The aim of this study was to evaluate the potential of iterative reconstruction (IR) in chest computed tomography (CT) to reduce radiation exposure. The qualitative and quantitative image quality of standard reconstructions with filtered back projection (FBP) and half dose (HD) chest CT data reconstructed with FBP and IR was assessed.


METHODS
52 consecutive patients underwent contrast-enhanced chest CT on a dual-source CT system at 120 kV and automatic exposure control. The tube current was equally split on both tube detector systems. For the HD datasets, only data from one tube detector system was utilized. Thus, FD and HD data was available for each patient with a single scan. Three datasets were reconstructed from the raw data: standard full dose (FD) images applying FBP which served as a reference, HD images applying FBP and IR. Objective image quality analysis was performed by measuring the image noise in tissue and air. The subjective image quality was evaluated by 2 radiologists according to European guidelines. Additional assessment of artifacts, lesion conspicuity and edge sharpness was performed.


RESULTS
Image noise did not differ significantly between HD-IR and FD-FBP (p = 0.254) but increased substantially in HD-FBP (p < 0.001). No statistically significant differences were found for the reproduction of anatomical and pathological structures between HD-IR and FD-FBP, subsegmental bronchi and bronchioli. The image quality of HD-FBP was rated inferior because of increased noise.


CONCLUSIONS
A 50 % dose reduction in contrast-enhanced chest CT is feasible without a loss of diagnostic confidence if IR is used for image data reconstruction. Iterative reconstruction is another powerful tool to reduce radiation exposure and can be combined with other dose-saving techniques.


CONCLUSIONS
• Iterative reconstructions allow for image noise and artifact reduction.• Comparable image data can thus be attained even at 50 % radiation dose.• Diagnostic confidence remains unaffected.
Department of Radiology, University Hospital Erlangen.
M S
MS
May
Department of Radiology, University Hospital Erlangen.
A
A
Eller
Department of Radiology, University Hospital Erlangen.
C
C
Stahl
Department of Radiology, University Hospital Erlangen.
W
W
Wuest
Department of Radiology, University Hospital Erlangen.
M
M
Scharf
Department of Radiology, University Hospital Erlangen.
M
M
Hammon
Department of Radiology, University Hospital Erlangen.
P
P
Dankerl
Department of Radiology, University Hospital Erlangen.
P M
PM
Schlechtweg
Healthcare, Siemens AG, Forchheim.
T
T
Allmendinger
Healthcare, Siemens AG, Forchheim.
M
M
Sedlmair
Healthcare, Siemens AG, Forchheim.
B
B
Schmidt
Department of Radiology, University Hospital Erlangen.
M
M
Uder
Department of Radiology, University Hospital Erlangen.
M M
MM
Lell
D000368:Aged; D001424:Bacterial Infections / Q000000981:diagnostic imaging; D004417:Dyspnea / Q000000981:diagnostic imaging / Q000209:etiology; D005260:Female; D005374:Filtration; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000379:methods*; D009367:Neoplasm Staging; D011829:Radiation Dosage; D013902:Radiography, Thoracic / Q000379:methods*; D012680:Sensitivity and Specificity; D013896:Thoracic Diseases / Q000000981:diagnostic imaging; D013899:Thoracic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology