Comparison of image quality in optical and radiographic magnification techniques for fine-detail skeletal radiography: effect of object thickness Page: 5 of 38
This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided to Digital Library by the UNT Libraries Government Documents Department.
The following text was automatically extracted from the image on this page using optical character recognition software:
that of Type M. Although the radiation per unit area of the hand
for the 4x radiographic magnification ircreases to approximately
16 tines that for contact radiography with RP-Detail, it is still
about 1/3 that for optical magnification. This dose reduction is one
of the advantages of the radiographic magnification technique.
Imaging Properties for Hand Radiography
The fundamental physical characteristics of imaging systems, i.e.,
contrast, sharpness, and noise, are evaluated by means of the char-
acteristic curve (and/or gradient curve) , the MTF, and the Wiener
spectrum, respectively. The characteristic curves and gradient for
Type 1.1 and RP-Detail film are shown in Fig. 2. The greater speed and
latitude of the screen-film system can be appreciated from the H 8 D
curves. From the gradient curves, we have selected an average density
of approximately 1.5 for hand radiographs with the RP-Detail, because
the film contrast is maximal at that density. A density of 2 or
greater is selected for radiographs with Type M, based on a radiologist's
evaluation of clinical radiographs. At these average densities, the
gradient of Type M is higher than that of RP-Detail by at least 25%,
depending on the density of Type N chosen. However, the scattered
radiation, which reduces the contrast of image details, is less for
the radiographic than for the optical magnification, due to the air
gap effect. According to our measurements on the hand phantom during
optical magnification, the scattered radiation relative to the primary
radiation was approximately 25-60%, depending on the location of the
phantom. Because of the air gap, which is inherent in the radiographic
Here’s what’s next.
This article can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Article.
Doi, K.; Genant, H.K. & Rossmann, K. Comparison of image quality in optical and radiographic magnification techniques for fine-detail skeletal radiography: effect of object thickness, article, January 1, 1974; United States. (https://digital.library.unt.edu/ark:/67531/metadc1021083/m1/5/: accessed May 23, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.