The dynamic range of digital radiographic systems: dose reduction or risk of overexposure?
OBJECTIVE
To investigate the range of diagnostically acceptable digital radiographs and film as a function of exposure time, as well as the relationship to dose reduction and consequences for dental practice.


METHODS
Five systems for intraoral radiography were used to take a series of radiographs, with increasing exposure times, of five different dry bone specimens. Seven observers evaluated the 25 series of radiographs. The observers had to determine which radiographs of each series were acceptable for dental diagnostics and which radiograph of each series they preferred.


RESULTS
For Ektaspeed Plus film, the exposure time for the preferred radiograph was 0.52 s, with a range of diagnostically acceptable radiographs from 0.23-1.02 s. The preferred radiograph of the solid-state systems required less radiation than film (Sirona, 0.13 s; MPDx 0.35 s). The exposure range of these systems is narrow. In contrast, the exposure range of the phosphor plate systems is very wide. The preferred radiograph of the phosphor plate systems required high exposure (Digora, 1.21 s; Gendex DenOptix, 1.16 s).


CONCLUSIONS
All digital systems require less exposure than film for diagnostically acceptable radiographs, but this is less obvious for preferred radiographs. Solid-state systems alert the dentist when a too long exposure time is used by a lack of image quality; phosphor plate systems, however, produce good quality radiographs even at high exposure times, which may result in an unnecessarily high dose.
Berkhout
W E R
WE
Department of Oral and Maxillofacial Radiology, Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam, The Netherlands. e.berkhout@acta.nl
Beuger
D A
DA
Sanderink
G C H
GC
van der Stelt
P F
PF
D000704:Analysis of Variance; D006801:Humans; D008334:Mandible / Q000000981:diagnostic imaging; D015588:Observer Variation; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000379:methods; D019252:Radiography, Dental, Digital / Q000295:instrumentation / Q000379:methods*; D018570:Risk Assessment; D013997:Time Factors; D014962:X-Ray Film; D014963:X-Ray Intensifying Screens