Diagnostic Radiology
The Role of Medical Physics in Diagnostic X-ray Services
The role of Medical Physics in medicine began with the discovery of X-rays by Roentgen
in 1895 and their subsequent use in diagnosis. The physicists’ role is therefore to apply
scientific expertise to the assessment and development of imaging equipment, the
monitoring and control of radiation doses to patients, staff and the general public and the
overall efficacy of imaging techniques.
1.
Quality Assurance
In the context of X-ray imaging, QA refers to those activities which ensure that
suitable X-ray imaging systems are purchase and their performance matches specified
criteria. QA can be considered as:
1.1 Identification, specification and choice of imaging equipments
The physicist, who is a member of the team responsible for choosing new
equipment, provides advice on the performance characteristics of imaging
systems and comments on the suitability of equipment for the proposed usage.
The physicist also establishes a liaison between the X-ray manufacturer and the
users as an impartial and objective assessor of the equipment.
1.2 Acceptance testing and performance evaluation
An objective assessment of equipment performance in a clinical environment is
made. This complements factory laboratory testing and the largely subjective
radiological assessment. The results of such as assessment of new equipment
determine, along with other factors, whether or not the equipment is acceptable
for clinical use.
Performance evaluation deals with the relationship between dose and image
quality and clinical application. Digital techniques such as Computed
Tomography (CT), demand extra expertise in computing and data handling.
The introduction of digital imaging in a wider context (digital fluorography and
digital radiography) requires the physicist to contribute to the evaluation and
analysis of digital images and in the longer term in the establishment of “digital
department”.
Acceptance tests for Radiographic and Fluoroscopic Systems:
Non-invasive technique
(a)
Generator calibration:
kVp:
Many noninvasive high voltage measuring systems are available. All systems
estimate the kVp based on a penetrometer measurement technique. The X-ray
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