This paper was presented on Monday, 30 November 1998 as part of the Scientific Sessions program at RSNA '98

Laser versus Charged Coupled Device (CCD) Digital Scanners: Qualitative Comparison at Differing Compression Ratios

Topics Associated with this Session: Images, digitization Picture archiving and communication system (PACS)

G.W. Boland, MD, Boston, MA * J.O. Shepard, MD * B.Trotson-Dickinson, MD * R.T. Bramson, MD * R.R. Mourtada, BS *E.F. Halpern, PhD

PURPOSE: Laser scanners are recognized to have superior quantitative parameters (optical density range) than CCD scanners*.However, no study has evaluated these scanners qualitatively. This study was therefore performed to qualitatively evaluate these scanners and therefore determine diagnostic quality of digitized images.

METHOD AND MATERIALS: 50 normal and 50 chest radiographs with subtle pneumothoraces (less than 5% hemi-thorax) were digitized using both laser and CCD scanners. Each film was blindly evaluated for the presence or absence of a pneumothorax using a 2K x 2K interactive diagnostic workstation with 4 radiologists (2 chest radiologists, 2 non-chest radiologists) and ROC analysis performed.

RESULTS: Each radiologist found no statistical difference for detection or absence of a pneumothorax at each compression ratio between laser versus scanner CCD (P value ranged from 0.09 to 0.95) except for one reader who found CCD was superior to laser at 20:1 compression (P =0.02).

CONCLUSIONS: These results suggest that laser scanners offer no qualitative superiority for digitized plain radiographic film over CCD scanners. This has cost implications when implementing a comprehensive teleradiology solution.

NOTES: The Cobrascan CX-612T and CX-812M film digitizers have the latest CCD technology with optical density ranges up to 3.6 - equal to current laser technology. The new Cobrascan CX-2000T exceeds the specifications of any other scanner available today, including all lasers.