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Takarabe S, Kuramoto T, Shibayama Y, Tsuru H, Tatsumi M, Kato T, Okamura K, Yoshiura K. Effect of beam quality and readout direction in the edge profile on the modulation transfer function of photostimulable phosphor systems via the edge method. J Med Imaging (Bellingham) 2021; 8:043501. [PMID: 34307736 PMCID: PMC8291077 DOI: 10.1117/1.jmi.8.4.043501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Accepted: 06/28/2021] [Indexed: 11/14/2022] Open
Abstract
Purpose: The objective of this study was to investigate the effects of (i) the difference in the beam qualities on the presampled modulation transfer function (MTF) using the edge method and (ii) the readout direction of the edge profile for the photostimulable phosphor (PSP) system. Approach: The International Electrotechnical Commission (IEC) defined a technique using the "radiation qualities based on a phantom made up of an aluminum added filter" (RQA). A general radiographic system with a tube voltage of 50 kV and 9.7 mm of additional aluminum filtration was used to conform the x-ray to the IEC-specified beam quality definition RQA3. Additionally, we employed two different beams with tube voltages of 60 and 70 kV using a dental x-ray unit. The MTF was measured in the readout direction from low-to-high exposure regions and vice versa with respect to the scanning and subscanning directions of the PSP system. Results: The difference in the 50%MTF value for all directions between 60 and 70 kV averaged less than 0.05 . The 50%MTF of RQA3 was on average 0.2 lower than the value for 60 kV for each direction. For all beam qualities, no difference was observed between the MTFs measured in the readout direction from the low-to-high exposure regions and vice versa. Conclusions: The MTFs, measured using the dental x-ray unit, were unaffected by the tube voltage, and they were slightly higher than those measured using the RQA3. Furthermore, the MTF was unaffected by the differences in the readout directions of the edge profile.
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Affiliation(s)
- Shinya Takarabe
- Kyushu University Hospital, Division of Radiology, Department of Medical Technology, Fukuoka, Japan
- Kyushu University, Department of Oral and Maxillofacial Radiology, Faculty of Dental Science, Fukuoka, Japan
| | - Taku Kuramoto
- Kyushu University Hospital, Division of Radiology, Department of Medical Technology, Fukuoka, Japan
| | - Yusuke Shibayama
- Kyushu University Hospital, Division of Radiology, Department of Medical Technology, Fukuoka, Japan
| | - Hiroki Tsuru
- Kyushu University Hospital, Division of Radiology, Department of Medical Technology, Fukuoka, Japan
| | - Masato Tatsumi
- Kyushu University Hospital, Division of Radiology, Department of Medical Technology, Fukuoka, Japan
| | - Toyoyuki Kato
- Kyushu University Hospital, Division of Radiology, Department of Medical Technology, Fukuoka, Japan
| | - Kazutoshi Okamura
- Kyushu University, Department of Oral and Maxillofacial Radiology, Faculty of Dental Science, Fukuoka, Japan
| | - Kazunori Yoshiura
- Kyushu University, Department of Oral and Maxillofacial Radiology, Faculty of Dental Science, Fukuoka, Japan
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Kuramoto T, Takarabe S, Okamura K, Shiotsuki K, Shibayama Y, Tsuru H, Akamine H, Tatsumi M, Kato T, Morishita J, Yoshiura K. Effect of differences in pixel size on image characteristics of digital intraoral radiographic systems: a physical and visual evaluation. Dentomaxillofac Radiol 2020; 49:20190378. [PMID: 32302229 PMCID: PMC7461739 DOI: 10.1259/dmfr.20190378] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 04/09/2020] [Accepted: 04/15/2020] [Indexed: 12/15/2022] Open
Abstract
OBJECTIVES To quantify and validate the effect of pixel size on a digital intraoral radiographic system according to International Electrotechnical Commission standards through physical and visual evaluations. METHODS The digital intraoral radiographic system used was the photostimulable phosphor imaging plate and scanner system. The system had three image capture modes: high-speed (HS), high-resolution (HR), and super high-resolution (SHR) with different pixels. The physical characteristics of the system were evaluated using presampled modulation transfer function (MTF) and the normalized noise power spectrum (NNPS). An aluminum (Al) step phantom with different depths of holes was used to acquire images under various exposure conditions. The average number of perceptible holes from all steps was plotted against each exposure dose. The results were compared to analyze the effects of pixel size on image quality of intraoral radiographs. RESULTS The MTF was slightly higher with SHR than with HR and HS. The NNPS with SHR showed about a 40% decrease in magnitude compared to HS. The total number of perceptible holes in the Al step phantom was higher with SHR than with HS and HR in all exposure conditions. CONCLUSIONS The MTF and NNPS obtained with different pixel size could be quantified by physical evaluation, and the differences were visually validated with Al step phantom. The SHR mode has the potential to decrease the radiation dose without compromising the image quality.
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Affiliation(s)
- Taku Kuramoto
- Division of Radiology, Department of Medical Technology, Kyushu University Hospital, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Shinya Takarabe
- Division of Radiology, Department of Medical Technology, Kyushu University Hospital, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Kazutoshi Okamura
- Department of Oral and Maxillofacial Radiology, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Kenshi Shiotsuki
- Medical Technology Department, Oita University Hospital, 1-1 Idaigaoka, Hasama-cho, Yufu-shi, Oita 879-5593, Japan
| | - Yusuke Shibayama
- Division of Radiology, Department of Medical Technology, Kyushu University Hospital, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Hiroki Tsuru
- Division of Radiology, Department of Medical Technology, Kyushu University Hospital, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Hiroshi Akamine
- Division of Radiology, Department of Medical Technology, Kyushu University Hospital, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Masato Tatsumi
- Division of Radiology, Department of Medical Technology, Kyushu University Hospital, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Toyoyuki Kato
- Division of Radiology, Department of Medical Technology, Kyushu University Hospital, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Junji Morishita
- Department of Health Sciences, Faculty of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Kazunori Yoshiura
- Department of Oral and Maxillofacial Radiology, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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Geha H, Nasseh I, Noujeim M. Evaluation of a Mathematical Model for Digital Image Enhancement. Open Dent J 2015; 9:292-6. [PMID: 26464598 PMCID: PMC4598423 DOI: 10.2174/1874210601509010292] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 03/11/2015] [Accepted: 05/25/2015] [Indexed: 11/22/2022] Open
Abstract
Objective : The purpose of this study is to compare the detected number of holes on a stepwedge on images resulting from the application of the 5th degree polynomial model compared to the images resulting from the application of linear enhancement. Material and Methods : A 10-step aluminum step wedge with holes randomly drilled on each step was exposed with three different kVp and five exposure times per kVp on a Schick33® sensor. The images were enhanced by brightness/contrast adjustment, histogram equalization and with the 5th degree polynomial model and compared to the original non-enhanced images by six observers in two separate readings. Results : There was no significant difference between the readers and between the first and second reading. There was a significant three-factor interaction among Method, Exposure time, and kVp in detecting holes. The overall pattern was: “Poly” results in the highest counts, “Original” in the lowest counts, with “B/C” and “Equalized” intermediate. Conclusion : The 5th degree polynomial model showed more holes when compared to the other modalities.
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Affiliation(s)
- Hassem Geha
- The University of Texas Health Science Center, San Antonio, United States
| | - Ibrahim Nasseh
- Department of Oral and Maxillofacial Radiology, Lebanese University, Beirut, Lebanon
| | - Marcel Noujeim
- The University of Texas Health Science Center, San Antonio, United States
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Brüllmann DD, d'Hoedt B. The modulation transfer function and signal-to-noise ratio of different digital filters: a technical approach. Dentomaxillofac Radiol 2011; 40:222-9. [PMID: 21493878 DOI: 10.1259/dmfr/33029984] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVES The aim of this study was to illustrate the influence of digital filters on the signal-to-noise ratio (SNR) and modulation transfer function (MTF) of digital images. The article will address image pre-processing that may be beneficial for the production of clinically useful digital radiographs with lower radiation dose. METHODS Three filters, an arithmetic mean filter, a median filter and a Gaussian filter (standard deviation (SD) = 0.4), with kernel sizes of 3 × 3 pixels and 5 × 5 pixels were tested. Synthetic images with exactly increasing amounts of Gaussian noise were created to gather linear regression of SNR before and after application of digital filters. Artificial stripe patterns with defined amounts of line pairs per millimetre were used to calculate MTF before and after the application of the digital filters. RESULTS The Gaussian filter with a 5 × 5 kernel size caused the highest noise suppression (SNR increased from 2.22, measured in the synthetic image, to 11.31 in the filtered image). The smallest noise reduction was found with the 3 × 3 median filter. The application of the median filters resulted in no changes in MTF at the different resolutions but did result in the deletion of smaller structures. The 5 × 5 Gaussian filter and the 5 × 5 arithmetic mean filter showed the strongest changes of MTF. CONCLUSIONS The application of digital filters can improve the SNR of a digital sensor; however, MTF can be adversely affected. As such, imaging systems should not be judged solely on their quoted spatial resolutions because pre-processing may influence image quality.
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Affiliation(s)
- D D Brüllmann
- Department of Oral Surgery, University Medical Center of the Johannes Gutenberg University Mainz, Germany.
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