Radiology in marine mammals has always been problematic due to the variability in thickness and the animal's habitat often being far away from the radiological processing equipment. This combination of factors results in frequent retakes of a radiographic exam and often means the marine mammal is out of the water for a longer period of time than is safe for the animal.
Digital radiology is any form of radiographic exposure that results in the final capture media being stored and able to be manipulated digitally. The two most common forms are computed radiology (CR) and direct digital radiology (DDR).
CR is a form of digital radiology in which x-rays expose a sheet of phosphorus material that is stored inside F/SR. This sheet is then loaded into a daylight processing unit and read by a laser scanner. It is then able to be stored or manipulated digitally.
DDR is the newer form of digital radiology in which x-rays expose a solid state single cassette with a cable attached that carries the exposure information directly to a computer that allows for immediate viewing, processing or storage.
Pros and Cons
The advantage of CR is that of reduced cost in comparison to DDR. All other advantages belong to the DDR class equipment. Newer technology, newer radiological algorithms and portable poolside instant processing and viewing are huge advantages in radiographing marine mammals.
All forms of digital radiology still require an x-ray generator. In recent years the availability of portable higher milliampere (MA) generators, such as the MinXray 100 HT has made poolside imaging much more convenient. Very large animals still require higher MA generators, such as the Sedecal 600 HF pushcart. Most dolphins and smaller animals can be well imaged with the 100 Ma or smaller generators.
The algorithm or computed parameters of the digital radiograph can be very important to the clinician as these parameters are what allows for the wide latitude and ability to resolve small gray scale areas inside deeper tissues. All algorithms are not created equal. Some are much better than others at resolving bone detail in deep tissue, such as Eklin EDR Mark II. You should always see a demonstration of the equipment and algorithms to see if it will image the tissues you are interested in.
During the presentation, I will show examples of the same tissues imaged with F/SR, CR and DDR.
Digital radiology, in particular DDR, has the potential of making radiology a much more convenient and useful tool in marine mammal medicine.