Management of routine QC testing of imaging equipment

Introduction

Management of the routine quality control (QC) of medical imaging equipment is a major responsibility of the clinical diagnostic medical physicist. “Management” includes developing the QC protocols, implementation of the program, oversight of the program, and responsibility for determining the need for corrective action.

Important Principles

The medical physicist must implement and manage the QC program. This requires an understanding the tests and the ability to explain the methods of acquiring data to the individuals carrying out the tests.

It is then the medical physicist’s responsibility to interpret the results of the tests and determine what, if any, corrective action is necessary, including requesting vendor or manufacturer service.
The frequency of testing must be determined by the medical physicist. It is difficult to specify a frequency for all facilities and equipment since the equipment and processes vary significantly from one facility to another. For example, older x-ray generators may be quite variable, requiring more frequent testing than newer equipment. In all cases it is prudent to error on the side of more frequent testing.

Most importantly, the QC program should focus on image quality and patient doses, i.e., how the image appears on the viewbox or display and the dose to the patient. Other measurements, such as the linearity of exposure vs milli-ampere-second, may be important during acceptance testing. These, typically, do not impact image quality and patient dose so should not be part of the QC program. The measurement of characteristics that seldom, if ever, change also should not be included in the QC program, e.g., measurement of the focal spot size, although the focal spot size measurement should be part of the acceptance testing of every new x-ray tube.

The key to an effective quality control program is to minimize the measurements required while optimizing clinical image quality and patient radiation dose.

Introduction to References

There are many references on this topic available in the literature and on the internet. The listing below is just a sample of that available. Several organizations, including IAEA, AAPM, BIR, and IPEM provide material relative to implementation of quality control programs.

In addition, there is significant information on the details of quality control programs in the section of the website entitled Performance Testing of Imaging Equipment.

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