Difference between revisions of "Projectional radiography"
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Because of '''geometric magnification''', distances measured on a projection become larger than the actual size of the imaged object: | Because of '''geometric magnification''', distances measured on a projection become larger than the actual size of the imaged object: | ||
| − | *Size<sub>Object</sub> = Size<sub>Projection</sub> * Source-object distance (SOD) / Source- | + | *Size<sub>Object</sub> = Size<sub>Projection</sub> * Source-object distance (SOD) / Source-detector distance (SDD).<ref>{{cite web|last=DICOM|title=DICOM PS3.3 - Information Object Definitions - Table C.8-30. XA Positioner Module Attributes|url=http://dicom.nema.org/medical/dicom/current/output/chtml/part03/sect_C.8.7.5.html#table_C.8-30|accessdate=2017-01-23|date=2016-11-21}}</ref> |
Alternative names for ''source-detector distance''(SDD) are ''source''<ref name=SID>{{cite web|url=http://medical-dictionary.thefreedictionary.com/source-to-image-receptor+distance|title=source-to-image-receptor distance|website=Farlex medical dictionary, in turn citing Mosby's Medical Dictionary, 9th edition.|accessdate=2018-01-28}}</ref>/''focus'' to ''detector''/''image-receptor''<ref name=SID/>/''film'' distance (SID<ref name=SID/>, FID or FRD). On lumbar and [[chest radiograph]]s, it is anticipated that the magnification factor is between 1.05 and 1.40.<ref>{{cite web|title=Implementation of unsharpness and noise into the model of the imaging system: Applications to chest and lumbar spine screen-film radiography|url=https://www.diva-portal.org/smash/get/diva2:327957/FULLTEXT01.pdf|author=M Sandborg, D R Dance, and G Alm Carlsson|website=Faculty of Health Sciences, Linköping University}} Report 90. Jan. 1999. ISRN: LIU-RAD-R-090</ref> Because of the uncertainty of the true size of objects seen on projectional radiography, their sizes are often compared to other structures within the body, such as dimensions of the [[vertebra]]e, or empirically by clinical experience.<ref>[https://books.google.se/books?id=JaL3AAAAQBAJ&pg=PA788 Page 788] in: {{cite book|title=Neuroimaging, Part 2 Volume 136 of Handbook of Clinical Neurology|author=Joseph C. Masdeu, R. Gilberto Gonzalez |publisher=Newnes|year=2016|isbn=9780702045387}}</ref> | Alternative names for ''source-detector distance''(SDD) are ''source''<ref name=SID>{{cite web|url=http://medical-dictionary.thefreedictionary.com/source-to-image-receptor+distance|title=source-to-image-receptor distance|website=Farlex medical dictionary, in turn citing Mosby's Medical Dictionary, 9th edition.|accessdate=2018-01-28}}</ref>/''focus'' to ''detector''/''image-receptor''<ref name=SID/>/''film'' distance (SID<ref name=SID/>, FID or FRD). On lumbar and [[chest radiograph]]s, it is anticipated that the magnification factor is between 1.05 and 1.40.<ref>{{cite web|title=Implementation of unsharpness and noise into the model of the imaging system: Applications to chest and lumbar spine screen-film radiography|url=https://www.diva-portal.org/smash/get/diva2:327957/FULLTEXT01.pdf|author=M Sandborg, D R Dance, and G Alm Carlsson|website=Faculty of Health Sciences, Linköping University}} Report 90. Jan. 1999. ISRN: LIU-RAD-R-090</ref> Because of the uncertainty of the true size of objects seen on projectional radiography, their sizes are often compared to other structures within the body, such as dimensions of the [[vertebra]]e, or empirically by clinical experience.<ref>[https://books.google.se/books?id=JaL3AAAAQBAJ&pg=PA788 Page 788] in: {{cite book|title=Neuroimaging, Part 2 Volume 136 of Handbook of Clinical Neurology|author=Joseph C. Masdeu, R. Gilberto Gonzalez |publisher=Newnes|year=2016|isbn=9780702045387}}</ref> | ||
Revision as of 17:31, 23 July 2018
Author:
Mikael Häggström [notes 1]
By location
- Neck
- X-ray of the thorax
- X-ray of the upper limb
- X-ray of the abdomen and pelvis
- Vertebral column
- Lower limb
Interpretation
Source-object distance (SOD), source-detector distance (SDD) and geometric unsharpness.[1]
Because of geometric magnification, distances measured on a projection become larger than the actual size of the imaged object:
- SizeObject = SizeProjection * Source-object distance (SOD) / Source-detector distance (SDD).[2]
Alternative names for source-detector distance(SDD) are source[3]/focus to detector/image-receptor[3]/film distance (SID[3], FID or FRD). On lumbar and chest radiographs, it is anticipated that the magnification factor is between 1.05 and 1.40.[4] Because of the uncertainty of the true size of objects seen on projectional radiography, their sizes are often compared to other structures within the body, such as dimensions of the vertebrae, or empirically by clinical experience.[5]
Geometric unsharpness is a decrease in the spatial resolution of an image because the X-rays from the generator comes from an area rather than a single dot, and is decreased by having the object closer to the detector.
Diseases
Cite error: <ref> tags exist for a group named "notes", but no corresponding <references group="notes"/> tag was found, or a closing </ref> is missing
- ↑ Bruce Blakeley, Konstantinos Spartiotis (2006). "Digital radiography for the inspection of small defects ". Insight 48 (2). Archived from the original. .
- ↑ DICOM (2016-11-21). DICOM PS3.3 - Information Object Definitions - Table C.8-30. XA Positioner Module Attributes. Retrieved on 2017-01-23.
- ↑ 3.0 3.1 3.2 . source-to-image-receptor distance. Farlex medical dictionary, in turn citing Mosby's Medical Dictionary, 9th edition.. Retrieved on 2018-01-28.
- ↑ M Sandborg, D R Dance, and G Alm Carlsson. Implementation of unsharpness and noise into the model of the imaging system: Applications to chest and lumbar spine screen-film radiography. Faculty of Health Sciences, Linköping University. Report 90. Jan. 1999. ISRN: LIU-RAD-R-090
- ↑ Page 788 in: Joseph C. Masdeu, R. Gilberto Gonzalez (2016). Neuroimaging, Part 2 Volume 136 of Handbook of Clinical Neurology . Newnes. ISBN 9780702045387.
