Relationship between radiation dose reduction and image quality change in photostimulable phosphor luminescence X-ray imaging systems.
OBJECTIVE
The aim of the study was to clarify the change in image quality upon X-ray dose reduction and to re-analyse the possibility of X-ray dose reduction in photostimulable phosphor luminescence (PSPL) X-ray imaging systems. In addition, the study attempted to verify the usefulness of multiobjective frequency processing (MFP) and flexible noise control (FNC) for X-ray dose reduction.


METHODS
Three PSPL X-ray imaging systems were used in this study. Modulation transfer function (MTF), noise equivalent number of quanta (NEQ) and detective quantum efficiency (DQE) were evaluated to compare the basic physical performance of each system. Subjective visual evaluation of diagnostic ability for normal anatomical structures was performed. The NEQ, DQE and diagnostic ability were evaluated at base X-ray dose, and 1/3, 1/10 and 1/20 of the base X-ray dose.


RESULTS
The MTF of the systems did not differ significantly. The NEQ and DQE did not necessarily depend on the pixel size of the system. The images from all three systems had a higher diagnostic utility compared with conventional film images at the base and 1/3 X-ray doses. The subjective image quality was better at the base X-ray dose than at 1/3 of the base dose in all systems. The MFP and FNC-processed images had a higher diagnostic utility than the images without MFP and FNC.


CONCLUSIONS
The use of PSPL imaging systems may allow a reduction in the X-ray dose to one-third of that required for conventional film. It is suggested that MFP and FNC are useful for radiation dose reduction.
Sakurai
T
T
Division of Radiology, Department of Maxillofacial Diagnostic Science, Kanagawa Dental College, Yokosuka, Kanagawa, 238-8580, Japan. sakurait@kdcnet.ac.jp
Kawamata
R
R
Kozai
Y
Y
Kaku
Y
Y
Nakamura
K
K
Saito
M
M
Wakao
H
H
Kashima
I
I
D000328:Adult; D000539:Alveolar Process / Q000000981:diagnostic imaging; D016477:Artifacts; D003743:Dental Enamel / Q000000981:diagnostic imaging; D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging; D003804:Dentin / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008334:Mandible / Q000000981:diagnostic imaging; D010513:Periodontal Ligament / Q000000981:diagnostic imaging; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000379:methods*; D016300:Radiography, Bitewing; D015898:Tomography Scanners, X-Ray Computed; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014092:Tooth Root / Q000000981:diagnostic imaging; D014962:X-Ray Film; D014963:X-Ray Intensifying Screens
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