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Subtraction Technic

Subtraction Technic Subtraction Technic 1 William Hanafee , M.D. and Paul Stout Medical Center University of California at Los Angeles Los Angeles 24, Calif. ↵ 1 From the Department of Radiology, University of California at Los Angeles, Calif. Based on a Scientific Exhibit to be presented at the Forty-eighth Annual Meeting of the Radiological Society of North America, Chicago, Ill., Nov. 25–30, 1962. Excerpt Subtraction technic is a photographic method for minimizing the confusing shadows caused by overlapping bone in angiographic studies. The method was first described in 1953 by Ziedses des Plantes (1), who has published several subsequent articles (2–4) on the subject in the Belgian, Dutch, and German literature. To date, however, nothing has appeared in English or American journals. We are reporting our experiences to make the method more generally available to the American radiologist. In order to explain the principle, cerebral angiography can best be used as an example. The patient's head is rigidly fixed to prevent motion. Even facial grimacing or tightening of the neck muscles during contrast injection may ruin the study. A single anteroposterior or lateral roentgenogram is taken prior to contrast injection, depending on the serial study being made. This will later become the base-line film for subtraction. Following this, and without moving the patient, serial changer, or x-ray tube, a routine contrast injection is made, followed by serial filming. The films are processed and viewed in the conventional manner. If more information is desired concerning an area obscured by bone, subtraction technic is performed (Fig. 1). This involves photography, and x-ray sources are no longer used. A contact print, using single emulsion photographic film, is made of the base-line roentgenogram taken prior to the injection of contrast material. On this first contact print we now have reversed the image; that is, “black” structures are now white and the white radiopaque structures, such as bone, appear black. This first contact print is then superimposed precisely on the roentgenogram of the series from which more information is desired. These two are firmly taped together, and a second contact print is made, with the use of single emulsion photographic film, by passing light through the two combined (first contact print and serial roentgenogram) to expose the emulsion of the second contact print. In this final print, background structures tend to “gray out.” The ordinary “white” of the skull has been made gray by the “black” areas of the contact print of the base-line film. Similarly, the heavy exposed “black” areas caused by air-containing structures are reduced to gray. The only thing which appears on one roentgenogram and not on the other is the injected contrast material. Therefore, the contrast-filled vessels are not grayed out. Essentials for subtraction technic are: A serial film changer for the radiographic portion of the examination. This is absolutely essential, together with some device for completely immobilizing the head. Photographic contact printer. The light source of the contact printer should be at a low level. This allows better control by maintaining exposures in the range of five seconds. Photographic film. Eastman Kodak Commercial Film has the desired sensitometric curve. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Radiology Radiological Society of North America, Inc.

Subtraction Technic

Hanafee, William; Stout, Paul
Radiology , Volume 79 (4): 658 – Oct 1, 1962
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Publisher
Radiological Society of North America, Inc.
Copyright
Copyright © 1962 by Radiological Society of North America
ISSN
1527-1315
eISSN
0033-8419
DOI
10.1148/79.4.658
pmid
13952459
Publisher site
See Article on Publisher Site

Abstract

Subtraction Technic 1 William Hanafee , M.D. and Paul Stout Medical Center University of California at Los Angeles Los Angeles 24, Calif. ↵ 1 From the Department of Radiology, University of California at Los Angeles, Calif. Based on a Scientific Exhibit to be presented at the Forty-eighth Annual Meeting of the Radiological Society of North America, Chicago, Ill., Nov. 25–30, 1962. Excerpt Subtraction technic is a photographic method for minimizing the confusing shadows caused by overlapping bone in angiographic studies. The method was first described in 1953 by Ziedses des Plantes (1), who has published several subsequent articles (2–4) on the subject in the Belgian, Dutch, and German literature. To date, however, nothing has appeared in English or American journals. We are reporting our experiences to make the method more generally available to the American radiologist. In order to explain the principle, cerebral angiography can best be used as an example. The patient's head is rigidly fixed to prevent motion. Even facial grimacing or tightening of the neck muscles during contrast injection may ruin the study. A single anteroposterior or lateral roentgenogram is taken prior to contrast injection, depending on the serial study being made. This will later become the base-line film for subtraction. Following this, and without moving the patient, serial changer, or x-ray tube, a routine contrast injection is made, followed by serial filming. The films are processed and viewed in the conventional manner. If more information is desired concerning an area obscured by bone, subtraction technic is performed (Fig. 1). This involves photography, and x-ray sources are no longer used. A contact print, using single emulsion photographic film, is made of the base-line roentgenogram taken prior to the injection of contrast material. On this first contact print we now have reversed the image; that is, “black” structures are now white and the white radiopaque structures, such as bone, appear black. This first contact print is then superimposed precisely on the roentgenogram of the series from which more information is desired. These two are firmly taped together, and a second contact print is made, with the use of single emulsion photographic film, by passing light through the two combined (first contact print and serial roentgenogram) to expose the emulsion of the second contact print. In this final print, background structures tend to “gray out.” The ordinary “white” of the skull has been made gray by the “black” areas of the contact print of the base-line film. Similarly, the heavy exposed “black” areas caused by air-containing structures are reduced to gray. The only thing which appears on one roentgenogram and not on the other is the injected contrast material. Therefore, the contrast-filled vessels are not grayed out. Essentials for subtraction technic are: A serial film changer for the radiographic portion of the examination. This is absolutely essential, together with some device for completely immobilizing the head. Photographic contact printer. The light source of the contact printer should be at a low level. This allows better control by maintaining exposures in the range of five seconds. Photographic film. Eastman Kodak Commercial Film has the desired sensitometric curve.

Journal

Radiology – Radiological Society of North America, Inc.

Published: Oct 1, 1962

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