Terminology Abbreviations and Definitions

1. Terminology Abbreviations:

2. Definitions:

 Diagnostic Imaging Provider - the person(s) who performs or supervises the performance of the diagnostic imaging service, and who usually provides the primary analysis and opinion on the obtained images.  This typically refers to radiologists, but may also include vascular surgeons, cardiologists, obstetricians and any other person who is appropriately accredited by the local regulatory authority.

 Diagnostic Quality Image - an image that is comparable in quality and presentation to that used by radiologists in reporting.

 In some cases it is important that a diagnostic quality image is measurable, and thus capable of being analysed to produce linear dimensions that the clinician will unambiguously understand.   Any technique may be used as long as the end user is able to obtain an accurate, reproducible linear measurement within the particular clinical environment

 Film - transparent polyester sheets, by which diagnostic images are distributed in hard copy as continuous tone shades of grey.  While such film can be generated by either photographic / analogue capture, or laser printed images derived from a digital image, for the purposes of this document, both forms are grouped under the term film.

 Lossless - data which when decompressed produces images identical to the original

 Lossy - data which when decompressed produces images of different (usually reduced) quality than the original

 Reduced Quality Image – Any image that is not a Diagnostic Quality Image

 Scout images (also known as “scout films”, “pilot images”, “topograms”, “surviews”) - images on which the location of cross-sectional image(s) relative to key anatomical landmarks may be displayed.  The scout image may be a digital projection radiograph (like a traditional ‘X-ray’), a cross-sectional image in another plane, or a projection image of a 3-dimensional model.  For spine studies, the scout images will typically be either a lateral projection radiograph (CT), or a mid-sagital cross-sectional image (CT or MRI).

 Scout images are used :
(1) to aid the technologist in planning the location(s) at which cross-sectional images are to be obtained, and choosing their orientation ;
(2) to enable the viewer of a cross-sectional image to define its relationship to the overall anatomy of the patient.

 Source image / Source data –  CT or MR imaging data which is generally the actual voxel information obtained during the cross sectional  image capture, and is an intermediate step between the image acquisition and the processed image data usually used for diagnostic interpretation - sometimes referred to as “thins” in CT parlance.  More complicated post-processing can convert these images into 3D representations of some or all of the anatomy included in the original part of he patient that was imaged – this is useful for unobstructed display of, e.g., bones, or arteries.
Although they may or may not be utilised during the reporting process, these data are available to reporting radiologists from the imaging modality itself for further processing or re-processing if required. Almost all are in DICOM format, and can be exported on PDI-compliant media if desired, however the data sets may be very large (e.g. >1000   512 x 512 matrix images), and can exceed the storage capacity of a single CD (or even a single DVD). Some specialised applications (e.g. some MR spectroscopy, 3D angiography, 3D ultrasound, some scintigraphy) use non-DICOM data formats, though many of these are moving towards DICOM representations.