Effects of scintillator on the modulation transfer function (MTF) of a digital imaging system

• Published in: Oral surgery, oral medicine, oral pathology, oral radiology and endodontics Vol. 99; no. 5; pp. 608 - 613
• Main Authors: Farman, Taeko T., Vandre, Robert H., Pajak, John C., Miller, Stuart R., Lempicki, Alex, Farman, Allan G.
• Format: Journal Article
• Language: English
• Published: St. Louis, MO Mosby, Inc 01.05.2005; Elsevier
• Subjects: Biological and medical sciences; Ceramics - chemistry; Cesium - chemistry; Dentistry; Equipment Design; Gadolinium - chemistry; Iodides - chemistry; Lutetium - chemistry; Medical sciences; Otorhinolaryngology. Stomatology; Radiography, Dental, Digital - instrumentation; Semiconductors; X-Ray Intensifying Screens; Medical imagery; Scintillator; Digital image; Transfer function; Modulation
• ISSN: 1079-2104; 1528-395X
• DOI: 10.1016/j.tripleo.2004.08.013

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. 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 μm. Two different x-ray generators were also used to evaluate this variable. MTF was investigated using the slanted slit method. 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. 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.