Radiology Case
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Figure 1: Movement of the patient or cassette during exposure causes the first artifact. The "L" marker does not have multiple exposures because it was likely attached to the cassette and did not move in relation to the film. There are actually multiple exposures of the humerus and ulna in this radiograph (arrows). This is caused by the fact that the x-ray beam is not constant but is pulsing rapidly every second during exposure. The number of pulses per second and the length of exposure determine how many images are seen.
Figure 2 and 3:The second artifact is a browning of the film with age due to incomplete washing. During the "fixing" of a radiograph, a substance called Thiosulfate is used to remove excess silver halide crystals. If the Thiosulfate is not completely washed from the film, it will undergo a reaction that causes a brown silver sulfide to form thus browning the image with time. This process is similar to the tarnishing of silver cookware by exposure to hydrogen sulfide from cooking gas. This artifact can occur in automatic processors if the rinse water was not turned on or with hand processing with inadequate washing.1
Radiographic artifacts can be difficult to identify for even the most experienced radiologists, and can be representative of problem areas in a radiology program. Use a systematic thought process beginning with the generation of x-rays and ending with the development of the radiograph when investigating artifacts. If you are having difficulty determining the origin of an artifact, consultation with a veterinary radiologist should be considered.
The images are courtesy of Washington State University, College of Veterinary Medicine, Department of Radiology.
- Curry T, Dowdey J, Murry j, RC. Christensen's Physics of Diagnostic Radiology. 4rth ed. Philadelphia: Lea & Febiger, 1990.
Dr. John Feleciano, DVM, DACVR
Dr. Renee Leveille, DVM, DACVR