Rvg Radiation Exposure

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Digital radiography is a form of radiography that uses x-ray–sensitive plates to directly capture data during the patient examination, immediately transferring it to a computer system without the use of an intermediate cassette. [1]Advantages include time efficiency through bypassing chemical processing and the ability to digitally transfer and enhance images. Also, less radiation can be used to produce an image of similar contrast to conventional radiography.

Instead of X-ray film, digital radiography uses a digital image capture device. This gives advantages of immediate image preview and availability; elimination of costly film processing steps; a wider dynamic range, which makes it more forgiving for over- and under-exposure; as well as the ability to apply special image processing techniques that enhance overall display quality of the image.

Detectors[edit]

Exposure time range from the lowest value of 0.08 sec to the highest value of 0.64 sec. The measured value for the exposure at different station from the nominal value show acceptable deviation not exceed 1.75%. The acceptability limit for exposure time is 10% deviation from the nominal value. Variation in measuring output radiation exposure. Radiation exposure associated with dentistry represents a minor contribution to the total exposure from all sources. The National Council on Radiation Protection and Measurements (NCRP) has estimated that the mean effective radiation dose from all sources in the U.S. Is 6.2 millisieverts (mSv) per year, with about half of this dose (i.e., 3.1 mSv) from natural sources (e.g., soil, radon).

Flat panel detectors[edit]

Flat panel detector used in digital radiography

Flat panel detectors (FPDs) are the most common kind of direct digital detectors.[2] They are classified in two main categories:

1. Indirect FPDsAmorphous silicon (a-Si) is the most common material of commercial FPDs. Combining a-Si detectors with a scintillator in the detector’s outer layer, which is made from caesium iodide (CsI) or gadolinium oxysulfide (Gd2O2S), converts X-rays to light. Because of this conversion the a-Si detector is considered an indirect imaging device. The light is channeled through the a-Si photodiode layer where it is converted to a digital output signal. The digital signal is then read out by thin film transistors (TFTs) or fiber-coupled CCDs.[3]

2. Direct FPDs. Amorphous selenium (a-Se) FPDs are known as “direct” detectors because X-ray photons are converted directly into charge. The outer layer of the flat panel in this design is typically a high-voltage bias electrode. X-ray photons create electron-hole pairs in a-Se, and the transit of these electrons and holes depends on the potential of the bias voltage charge. As the holes are replaced with electrons, the resultant charge pattern in the selenium layer is read out by a TFT array, active matrix array, electrometer probes or microplasma line addressing.[3][4]

Other direct digital detectors[edit]

Detectors based on CMOS and charge coupled device (CCD) have also been developed, but despite lower costs compared to FPDs of some systems, bulky designs and worse image quality have precluded widespread adoption.[5]

A high-density line-scan solid state detector is composed of a photostimulable barium fluorobromide doped with europium (BaFBr:Eu) or caesium bromide (CsBr) phosphor. The phosphor detector records the X-ray energy during exposure and is scanned by a laser diode to excite the stored energy which is released and read out by a digital image capture array of a CCD.

Phosphor plate radiography[edit]

Phosphor plate radiography[6] resembles the old analogue system of a light sensitive film sandwiched between two x-ray sensitive screens, the difference being the analogue film has been replaced by an imaging plate with photostimulable phosphor (PSP), which records the image to be read by an image reading device, which transfers the image usually to a Picture archiving and communication system (PACS).[6] It is also called photostimulable phosphor (PSP) plate-based radiography or computed radiography[7] (not to be confused with computed tomography which uses computer processing to convert multiple projectional radiographies to a 3D image).

After X-ray exposure the plate (sheet) is placed in a special scanner where the latent image is retrieved point by point and digitized, using laser light scanning. The digitized images are stored and displayed on the computer screen.[7] Phosphor plate radiography has been described as having an advantage of fitting within any pre-existing equipment without modification because it replaces the existing film; however, it includes extra costs for the scanner and replacement of scratched plates.

Initially phosphor plate radiography was the system of choice; early DR[clarification needed] systems were prohibitively expensive (each cassette costs £40-£50K), and as the 'technology was being taken to the patient', prone to damage.[8] Since there is no physical printout, and after the readout process a digital image is obtained, CR[clarification needed] has been known[by whom?] as an indirect digital technology, bridging the gap between x-ray film and fully digital detectors.[9][10]

What is the limit for radiation exposure

Industrial usage[edit]

Security[edit]

EOD (Explosive Ordnance Disposal) training and material testing. A 105 mm shell is radiographied with battery powered portable X-ray generator and flat panel detector.

Digital radiography (DR) has existed in various forms (for example, CCD and amorphous Silicon imagers) in the security X-ray inspection field for over 20 years and is steadily replacing the use of film for inspection X-rays in the Security and nondestructive testing (NDT) fields.[11] DR has opened a window of opportunity for the security NDT industry due to several key advantages including excellent image quality, high POD (probability of detection), portability, environmental friendliness and immediate imaging.[12]

Materials[edit]

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Nondestructive testing of materials is vital in fields such as aerospace and electronics where integrity of materials is vital for safety and cost reasons.[13] Advantages of digital technologies include the ability to provide results in real time.[14]

History[edit]

Direct x-ray imaging system (DXIS) - real time display

Key developments[edit]

1983Phosphor stimulated radiography systems first brought into clinical use by Fujifilm Medical Systems.[15][16][17]
1987Digital radiography in dentistry first introduced as 'RadioVisioGraphy'.[18]
1995French company Signet introduce the first dental digital panoramic system.[19]
First amorphous silicon and amorphous selenium detectors introduced.[20][21]
2001First commercial indirect CsI FPD for mammography and general radiography made available.[22]
2003Wireless CMOS detectors for dental work first made available by Schick Technologies.[23]

See also[edit]

References[edit]

  1. ^Marchiori, Dennis M. Clinical Imaging: with Skeletal, Chest, and Abdominal Pattern Differentials. Elsevier Mosby, 2014.
  2. ^Neitzel, U. (17 May 2005). 'Status and prospects of digital detector technology for CR and DR'. Radiation Protection Dosimetry. 114 (1–3): 32–38. doi:10.1093/rpd/nch532. PMID15933078.
  3. ^ abLança, Luís; Silva, Augusto (2013). 'Digital Radiography Detectors: A Technical Overview'. Digital imaging systems for plain radiography. New York: Springer. pp. 14–17. doi:10.1007/978-1-4614-5067-2_2. hdl:10400.21/1932. ISBN978-1-4614-5066-5.
  4. ^Ristić, Goran S (2013). 'The digital flat-panel X-Ray detectors'(PDF). Third Conference on Medical Physics and Biomedical Engineering, 18-19 Oct 2013. Skopje (Macedonia, The Former Yugoslav Republic of). 45 (10): 65–71.
  5. ^Verma, BS; Indrajit, IK (2008). 'Impact of computers in radiography: The advent of digital radiography, Part-2'. Indian Journal of Radiology and Imaging. 18 (3): 204–9. doi:10.4103/0971-3026.41828. PMC2747436. PMID19774158.
  6. ^ abBenjamin S (2010). 'Phosphor plate radiography: an integral component of the filmless practice'. Dent Today. 29 (11): 89. PMID21133024.
  7. ^ abRowlands, JA (7 December 2002). 'The physics of computed radiography'. Physics in Medicine and Biology. 47 (23): R123-66. doi:10.1088/0031-9155/47/23/201. PMID12502037.
  8. ^Freiherr, Greg (6 November 2014). 'The Eclectic History of Medical Imaging'. Imaging Technology News.
  9. ^Allisy-Roberts, Penelope; Williams, Jerry R. (2007-11-14). Farr's Physics for Medical Imaging. Elsevier Health Sciences. p. 86. ISBN978-0702028441.
  10. ^Holmes, Ken; Elkington, Marcus; Harris, Phil (2013-10-10). Clark's Essential Physics in Imaging for Radiographers. CRC Press. p. 83. ISBN9781444165036.
  11. ^Mery, Domingo (2015-07-24). Computer Vision for X-Ray Testing: Imaging, Systems, Image Databases, and Algorithms. Springer. p. 2. ISBN9783319207476.
  12. ^'A Review of Digital Radiography in the Service of Aerospace'. Vidisco. Retrieved 2021-02-02.
  13. ^Hanke, Randolf; Fuchs, Theobald; Uhlmann, Norman (June 2008). 'X-ray based methods for non-destructive testing and material characterization'. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 591 (1): 14–18. doi:10.1016/j.nima.2008.03.016.
  14. ^Ravindran, V R (2006). Digital Radiography Using Flat Panel Detector for the Non-DestructiveEvaluation of Space Vehicle Components(PDF). National Seminar on Non-Destructive Evaluation. Hyderabad: Indian Society for Non-Destructive Testing.
  15. ^Sonoda, M; Takano, M; Miyahara, J; Kato, H (September 1983). 'Computed radiography utilizing scanning laser stimulated luminescence'. Radiology. 148 (3): 833–838. doi:10.1148/radiology.148.3.6878707. PMID6878707.
  16. ^Bansal, G J (1 July 2006). 'Digital radiography. A comparison with modern conventional imaging'. Postgraduate Medical Journal. 82 (969): 425–428. doi:10.1136/pgmj.2005.038448. PMC2563775. PMID16822918.
  17. ^Mattoon, John S.; Smith, Carin (2004). 'Breakthroughs in Radiography Computed Radiography'. Compendium. 26 (1). Introduced in the 1980s by Fujifilm Medical Systems, computed radiography (CR)...
  18. ^Frommer, Herbert H.; Stabulas-Savage, Jeanine J. (2014-04-14). Radiology for the Dental Professional - E-Book. Elsevier Health Sciences. p. 288. ISBN9780323291156.
  19. ^Nissan, Ephraim (2012-06-15). Computer Applications for Handling Legal Evidence, Police Investigation and Case Argumentation. Springer Science & Business Media. p. 1009. ISBN9789048189908.
  20. ^Zhao, Wei; Rowlands, J. A. (October 1995). 'X-ray imaging using amorphous selenium: Feasibility of a flat panel self-scanned detector for digital radiology'. Medical Physics. 22 (10): 1595–1604. doi:10.1118/1.597628. PMID8551983.
  21. ^Antonuk, L E; Yorkston, J; Huang, W; Siewerdsen, J H; Boudry, J M; el-Mohri, Y; Marx, M V (July 1995). 'A real-time, flat-panel, amorphous silicon, digital x-ray imager'. RadioGraphics. 15 (4): 993–1000. doi:10.1148/radiographics.15.4.7569143. PMID7569143.
  22. ^Kim, H K; Cunningham, I A; Yin, Z; Cho, G (2008). 'On the development of digital radiography detectors: A review'(PDF). International Journal of Precision Engineering and Manufacturing. 9 (4): 86–100.
  23. ^Berman, Louis H.; Hargreaves, Kenneth M.; Cohen, Steven R. (2010-05-10). Cohen's Pathways of the Pulp Expert Consult. Elsevier Health Sciences. p. 108. ISBN978-0323079075.
Retrieved from 'https://en.wikipedia.org/w/index.php?title=Digital_radiography&oldid=1004413128'

Digital radiography is a form of radiography that uses x-ray–sensitive plates to directly capture data during the patient examination, immediately transferring it to a computer system without the use of an intermediate cassette. [1]Advantages include time efficiency through bypassing chemical processing and the ability to digitally transfer and enhance images. Also, less radiation can be used to produce an image of similar contrast to conventional radiography.

Instead of X-ray film, digital radiography uses a digital image capture device. This gives advantages of immediate image preview and availability; elimination of costly film processing steps; a wider dynamic range, which makes it more forgiving for over- and under-exposure; as well as the ability to apply special image processing techniques that enhance overall display quality of the image.

Detectors[edit]

Flat panel detectors[edit]

Flat panel detector used in digital radiography

Flat panel detectors (FPDs) are the most common kind of direct digital detectors.[2] They are classified in two main categories:

1. Indirect FPDsAmorphous silicon (a-Si) is the most common material of commercial FPDs. Combining a-Si detectors with a scintillator in the detector’s outer layer, which is made from caesium iodide (CsI) or gadolinium oxysulfide (Gd2O2S), converts X-rays to light. Because of this conversion the a-Si detector is considered an indirect imaging device. The light is channeled through the a-Si photodiode layer where it is converted to a digital output signal. The digital signal is then read out by thin film transistors (TFTs) or fiber-coupled CCDs.[3]

2. Direct FPDs. Amorphous selenium (a-Se) FPDs are known as “direct” detectors because X-ray photons are converted directly into charge. The outer layer of the flat panel in this design is typically a high-voltage bias electrode. X-ray photons create electron-hole pairs in a-Se, and the transit of these electrons and holes depends on the potential of the bias voltage charge. As the holes are replaced with electrons, the resultant charge pattern in the selenium layer is read out by a TFT array, active matrix array, electrometer probes or microplasma line addressing.[3][4]

Rvg Radiation Exposure Guidelines

Other direct digital detectors[edit]

Detectors based on CMOS and charge coupled device (CCD) have also been developed, but despite lower costs compared to FPDs of some systems, bulky designs and worse image quality have precluded widespread adoption.[5]

A high-density line-scan solid state detector is composed of a photostimulable barium fluorobromide doped with europium (BaFBr:Eu) or caesium bromide (CsBr) phosphor. The phosphor detector records the X-ray energy during exposure and is scanned by a laser diode to excite the stored energy which is released and read out by a digital image capture array of a CCD.

Phosphor plate radiography[edit]

Phosphor plate radiography[6] resembles the old analogue system of a light sensitive film sandwiched between two x-ray sensitive screens, the difference being the analogue film has been replaced by an imaging plate with photostimulable phosphor (PSP), which records the image to be read by an image reading device, which transfers the image usually to a Picture archiving and communication system (PACS).[6] It is also called photostimulable phosphor (PSP) plate-based radiography or computed radiography[7] (not to be confused with computed tomography which uses computer processing to convert multiple projectional radiographies to a 3D image).

After X-ray exposure the plate (sheet) is placed in a special scanner where the latent image is retrieved point by point and digitized, using laser light scanning. The digitized images are stored and displayed on the computer screen.[7] Phosphor plate radiography has been described as having an advantage of fitting within any pre-existing equipment without modification because it replaces the existing film; however, it includes extra costs for the scanner and replacement of scratched plates.

Initially phosphor plate radiography was the system of choice; early DR[clarification needed] systems were prohibitively expensive (each cassette costs £40-£50K), and as the 'technology was being taken to the patient', prone to damage.[8] Since there is no physical printout, and after the readout process a digital image is obtained, CR[clarification needed] has been known[by whom?] as an indirect digital technology, bridging the gap between x-ray film and fully digital detectors.[9][10]

Industrial usage[edit]

Security[edit]

EOD (Explosive Ordnance Disposal) training and material testing. A 105 mm shell is radiographied with battery powered portable X-ray generator and flat panel detector.

Digital radiography (DR) has existed in various forms (for example, CCD and amorphous Silicon imagers) in the security X-ray inspection field for over 20 years and is steadily replacing the use of film for inspection X-rays in the Security and nondestructive testing (NDT) fields.[11] DR has opened a window of opportunity for the security NDT industry due to several key advantages including excellent image quality, high POD (probability of detection), portability, environmental friendliness and immediate imaging.[12]

Materials[edit]

Nondestructive testing of materials is vital in fields such as aerospace and electronics where integrity of materials is vital for safety and cost reasons.[13] Advantages of digital technologies include the ability to provide results in real time.[14]

History[edit]

Direct x-ray imaging system (DXIS) - real time display

Key developments[edit]

1983Phosphor stimulated radiography systems first brought into clinical use by Fujifilm Medical Systems.[15][16][17]
1987Digital radiography in dentistry first introduced as 'RadioVisioGraphy'.[18]
1995French company Signet introduce the first dental digital panoramic system.[19]
First amorphous silicon and amorphous selenium detectors introduced.[20][21]
2001First commercial indirect CsI FPD for mammography and general radiography made available.[22]
2003Wireless CMOS detectors for dental work first made available by Schick Technologies.[23]

See also[edit]

Radiation

References[edit]

  1. ^Marchiori, Dennis M. Clinical Imaging: with Skeletal, Chest, and Abdominal Pattern Differentials. Elsevier Mosby, 2014.
  2. ^Neitzel, U. (17 May 2005). 'Status and prospects of digital detector technology for CR and DR'. Radiation Protection Dosimetry. 114 (1–3): 32–38. doi:10.1093/rpd/nch532. PMID15933078.
  3. ^ abLança, Luís; Silva, Augusto (2013). 'Digital Radiography Detectors: A Technical Overview'. Digital imaging systems for plain radiography. New York: Springer. pp. 14–17. doi:10.1007/978-1-4614-5067-2_2. hdl:10400.21/1932. ISBN978-1-4614-5066-5.
  4. ^Ristić, Goran S (2013). 'The digital flat-panel X-Ray detectors'(PDF). Third Conference on Medical Physics and Biomedical Engineering, 18-19 Oct 2013. Skopje (Macedonia, The Former Yugoslav Republic of). 45 (10): 65–71.
  5. ^Verma, BS; Indrajit, IK (2008). 'Impact of computers in radiography: The advent of digital radiography, Part-2'. Indian Journal of Radiology and Imaging. 18 (3): 204–9. doi:10.4103/0971-3026.41828. PMC2747436. PMID19774158.
  6. ^ abBenjamin S (2010). 'Phosphor plate radiography: an integral component of the filmless practice'. Dent Today. 29 (11): 89. PMID21133024.
  7. ^ abRowlands, JA (7 December 2002). 'The physics of computed radiography'. Physics in Medicine and Biology. 47 (23): R123-66. doi:10.1088/0031-9155/47/23/201. PMID12502037.
  8. ^Freiherr, Greg (6 November 2014). 'The Eclectic History of Medical Imaging'. Imaging Technology News.
  9. ^Allisy-Roberts, Penelope; Williams, Jerry R. (2007-11-14). Farr's Physics for Medical Imaging. Elsevier Health Sciences. p. 86. ISBN978-0702028441.
  10. ^Holmes, Ken; Elkington, Marcus; Harris, Phil (2013-10-10). Clark's Essential Physics in Imaging for Radiographers. CRC Press. p. 83. ISBN9781444165036.
  11. ^Mery, Domingo (2015-07-24). Computer Vision for X-Ray Testing: Imaging, Systems, Image Databases, and Algorithms. Springer. p. 2. ISBN9783319207476.
  12. ^'A Review of Digital Radiography in the Service of Aerospace'. Vidisco. Retrieved 2021-02-02.
  13. ^Hanke, Randolf; Fuchs, Theobald; Uhlmann, Norman (June 2008). 'X-ray based methods for non-destructive testing and material characterization'. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 591 (1): 14–18. doi:10.1016/j.nima.2008.03.016.
  14. ^Ravindran, V R (2006). Digital Radiography Using Flat Panel Detector for the Non-DestructiveEvaluation of Space Vehicle Components(PDF). National Seminar on Non-Destructive Evaluation. Hyderabad: Indian Society for Non-Destructive Testing.
  15. ^Sonoda, M; Takano, M; Miyahara, J; Kato, H (September 1983). 'Computed radiography utilizing scanning laser stimulated luminescence'. Radiology. 148 (3): 833–838. doi:10.1148/radiology.148.3.6878707. PMID6878707.
  16. ^Bansal, G J (1 July 2006). 'Digital radiography. A comparison with modern conventional imaging'. Postgraduate Medical Journal. 82 (969): 425–428. doi:10.1136/pgmj.2005.038448. PMC2563775. PMID16822918.
  17. ^Mattoon, John S.; Smith, Carin (2004). 'Breakthroughs in Radiography Computed Radiography'. Compendium. 26 (1). Introduced in the 1980s by Fujifilm Medical Systems, computed radiography (CR)...
  18. ^Frommer, Herbert H.; Stabulas-Savage, Jeanine J. (2014-04-14). Radiology for the Dental Professional - E-Book. Elsevier Health Sciences. p. 288. ISBN9780323291156.
  19. ^Nissan, Ephraim (2012-06-15). Computer Applications for Handling Legal Evidence, Police Investigation and Case Argumentation. Springer Science & Business Media. p. 1009. ISBN9789048189908.
  20. ^Zhao, Wei; Rowlands, J. A. (October 1995). 'X-ray imaging using amorphous selenium: Feasibility of a flat panel self-scanned detector for digital radiology'. Medical Physics. 22 (10): 1595–1604. doi:10.1118/1.597628. PMID8551983.
  21. ^Antonuk, L E; Yorkston, J; Huang, W; Siewerdsen, J H; Boudry, J M; el-Mohri, Y; Marx, M V (July 1995). 'A real-time, flat-panel, amorphous silicon, digital x-ray imager'. RadioGraphics. 15 (4): 993–1000. doi:10.1148/radiographics.15.4.7569143. PMID7569143.
  22. ^Kim, H K; Cunningham, I A; Yin, Z; Cho, G (2008). 'On the development of digital radiography detectors: A review'(PDF). International Journal of Precision Engineering and Manufacturing. 9 (4): 86–100.
  23. ^Berman, Louis H.; Hargreaves, Kenneth M.; Cohen, Steven R. (2010-05-10). Cohen's Pathways of the Pulp Expert Consult. Elsevier Health Sciences. p. 108. ISBN978-0323079075.

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