Effects of scintillator on the modulation transfer function (MTF) of a digital imaging system.
OBJECTIVE
To investigate the effects of 2 components (scintillator and x-ray generator) in the imaging chain on the modulation transfer function (MTF) of a charge-coupled device (CCD) digital intraoral radiographic system.


METHODS
Three screens composed of 3 different scintillator materials, namely europium-doped lutetium oxide transparent optical ceramic (TOC), thallium-doped cesium iodide (CsI), and terbium-doped gadolinium oxysulfide (GOS), were compared. Each was used, in turn, in conjunction with a CCD detector having a pixel dimension of 19.5 mum. Two different x-ray generators were also used to evaluate this variable. MTF was investigated using the slanted slit method.


RESULTS
The TOC provided a good modulation response for low and middle frequencies, reducing to 0 only at a high cutoff frequency. With CsI and GOS, the system MTF dropped to 0 at a lower cutoff frequency than was the case with TOC. Hence, TOC provided higher spatial resolution than the other 2 scintillators tested under the experimental conditions applied. The differences in MTF attributed to the scintillator type were proportional and consistent.


CONCLUSIONS
Despite constant pixel dimensions, MTF was affected to a considerable degree by the scintillator applied and the x-ray generator used in conjunction with the same CCD imaging device. TOC shows potential as a possible replacement for CsI and GOS as a scintillator screen material for intraoral digital x-ray imaging using a solid-state detector, providing higher spatial resolution under the given experimental conditions.
Farman
Taeko T
TT
Division of Radiology and Imaging Sciences, Department of Surgical and Hospital Dentistry, The University of Louisville, Kentucky 40292, USA.
Vandre
Robert H
RH
Pajak
John C
JC
Miller
Stuart R
SR
Lempicki
Alex
A
Farman
Allan G
AG
D002516:Ceramics / Q000737:chemistry; D002586:Cesium / Q000737:chemistry; D004867:Equipment Design; D005682:Gadolinium / Q000737:chemistry; D007454:Iodides / Q000737:chemistry; D008187:Lutetium / Q000737:chemistry; D019252:Radiography, Dental, Digital / Q000295:instrumentation*; D012666:Semiconductors; D014963:X-Ray Intensifying Screens
D007454:Iodides; C021197:gadolinium sulfoxylate; D002586:Cesium; D008187:Lutetium; D005682:Gadolinium; C040050:cesium iodide