Quality Criteria are presented for a number of selected CT examinations. They apply to adult patients of standard size (~70kg mass and ~170cm height) undergoing usual application of the technique for the type of examination under consideration. These Quality Criteria are to be used by radiologists, operators and medical physicists as a check on the routine performance of the entire imaging process. The Quality Criteria are helpful for the immediate checking of the quality of imaging performance while the patient is still in the scanner.
However, the Quality Criteria cannot be applied to all cases. For certain clinical indications a lower level of image quality may be acceptable but this should always be associated with a lower radiation dose to the patient.
For each selected CT examination certain preparatory steps are necessary to ensure full justification and accurate control of the examination: - Indications, - Advisable preliminary investigations, - Patient preparation and - Scan projection radiograph. These will be given at the top of the List of Quality Criteria for each type of examination. The Quality Criteria are divided into the following three parts that are generally characteristic for the CT procedures, in addition to a fourth part which takes into account special clinical conditions:
| 1. | DIAGNOSTIC REQUIREMENTS
These list image criteria which specify important anatomical structures that should be visible in the image to aid accurate diagnosis. A qualitative guide to the necessary degree of visibility of these essential structures is provided in the following Description of Terms. |
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| 2. | CRITERIA FOR RADIATION DOSE TO THE PATIENT
Reference dose values are provided as far as available, in relation to technique for a standard-sized patient for each type of CT examination considered. These quantities are defined in Appendix 1 to Chapter 1 and discussed in detail in Chapter 2. |
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| 3. | EXAMPLE OF GOOD IMAGING TECHNIQUE
This section provides examples of CT technique parameters which facilitate good imaging performance that is capable of meeting all the above Quality Criteria. If radiologists and operators find that Diagnostic Requirements or Criteria for Radiation Dose to the Patient are not met, then the Example of Good Imaging Technique can be used as a guide to how their technique might be improved. |
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| 4. | CLINICAL CONDITIONS WITH IMPACT ON IMAGING PERFORMANCE
A number of conditions due to patient behaviour and technical particularities are listed which require special awareness and intervention of the operator. |
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