Lung cancer screening with CT: evaluation of radiologists and different computer assisted detection software (CAD) as first and second readers for lung nodule detection at different dose levels.
OBJECTIVE
To find the best pairing of first and second reader at highest sensitivity for detecting lung nodules with CT at various dose levels.


METHODS
An anthropomorphic lung phantom and artificial lung nodules were used to simulate screening CT-examination at standard dose (100 mAs, 120 kVp) and 8 different low dose levels, using 120, 100 and 80 kVp combined with 100, 50 and 25 mAs. At each dose level 40 phantoms were randomly filled with 75 solid and 25 ground glass nodules (5-12 mm). Two radiologists and 3 different computer aided detection softwares (CAD) were paired to find the highest sensitivity.


RESULTS
Sensitivities at standard dose were 92%, 90%, 84%, 79% and 73% for reader 1, 2, CAD1, CAD2, CAD3, respectively. Combined sensitivity for human readers 1 and 2 improved to 97%, (p1=0.063, p2=0.016). Highest sensitivities--between 97% and 99.0%--were achieved by combining any radiologist with any CAD at any dose level. Combining any two CADs, sensitivities between 85% and 88% were significantly lower than for radiologists combined with CAD (p<0.03).


CONCLUSIONS
Combination of a human observer with any of the tested CAD systems provide optimal sensitivity for lung nodule detection even at reduced dose at 25 mAs/80 kVp.
Department of Diagnostic, Interventional und Pediatric Radiology, University Hospital, Inselspital, Bern, Switzerland. Electronic address: andreas.christe@insel.ch.
A
A
Christe
L
L
Leidolt
A
A
Huber
P
P
Steiger
Z
Z
Szucs-Farkas
J E
JE
Roos
J T
JT
Heverhagen
L
L
Ebner
D004307:Dose-Response Relationship, Radiation; D055088:Early Detection of Cancer / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D015588:Observer Variation; D010363:Pattern Recognition, Automated; D019047:Phantoms, Imaging; D011361:Professional Competence; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012984:Software; D012986:Software Validation; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*
CAD; Ground glass nodule; Low-dose CT; Lung cancer screening; Lung nodules