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Radiation protection of patients during interventional cardiology

» Are radiation induced skin injuries common among patients undergoing interventions?

No.

Radiation induced skin injuries happen very rarely and the rough estimate is around one in 10,000 interventions. This figure can vary by a large margin as many injuries go unreported. The skin injuries can vary from mild erythema to deep skin ulceration. Many interventionalists still do not acknowledge that skin injuries have or could occur. Such denial has led, in many cases, to uncertain and ill-directed care for some patients. Injuries occur weeks or months after the interventional procedure was performed and could create problems in diagnosis. Most of these injuries can be avoided by using established radiation protection approaches.

»  What problems are associated with diagnosis of such injuries?

Experience has shown that patients normally go to a physician or dermatologist when symptoms are detected. The delay between the interventional procedure and occurrence of symptoms coupled with the lack of instruction by the interventionalist to report back to him if there is any skin irritation on ports of entries of the X-ray beam (typically patient's back), are responsible for misdiagnosis. There have been situations of misdiagnosis as insect bites, electrical burns, chemical burns or contact dermatitis. Typically in radiation induced injuries, normal methods of treatment with creams fail to give relief to the patient.

»  Can radiation injuries be prevented?

In most, if not all cases, the answer is ‘yes’, at least as far as the severe injuries are concerned. The experience from a centre where cardiologists were trained in radiological protection and the equipment was monitored and covered by a quality control programme indicates an absence of skin injuries in patients who underwent 5-7 PTCAs and 5-14 additional angiographies. 

»  How high is the patient exposure in cardiac interventions in comparison to chest radiograph?

Entrance exposure to patients in diagnostic and therapeutic angiography might be a few hundreds to even a thousand times more than in a chest radiograph. It must be emphasized that this way of comparing is an over-simplification as exposure situations are not similar. 

»  Which factors can affect patient dose in cardiac interventions?

There are patient, equipment and procedure dependent factors.

Patient factors include: body mass or body thickness in the beam, complexity of the lesion and anatomic target structure, radiosensitivity of some patients (ataxia telangiectasia); connective tissue disease and diabetes mellitus. 

Equipment factors include: setting done by the manufacturer on fluoro- and cine mode, appropriate quality control, existence of cine loop, last image hold, pre-selectable number of radiographic frames per run and virtual collimation.

The main procedure related factors are: number of radiographic frames per run, collimation, the fluoroscopic and radiographic acquisition modes, fluoroscopy time, wedge filter, magnification, distance of patient to image receptor (image intensifier or flat panel detector), distance between X-ray tube and patient and tube angulations. For further details please consult the references below.

»  How can I manage patient exposure?

Patient’s anatomic state, e.g. weight and the complexity of intervention are relevant and may be fixed, but a number of factors can help the interventionalist in patient exposure management. Collimation, a commonly neglected factor can prove to be the most efficient influencing factor. Restriction to the essential number of radiographic frames and to adequate (required image information) instead of best-possible image quality are more efficient than the potential of optimisation of fluoroscopy time. Further, adequately short radiographic runs, inspiration during radiography, avoid irradiating arms and breast, use means to monitor exposure, preference of less irradiating angulations, e.g. short skin-to-image-intensifier distance, use of the lowest image magnification compatible with the clinical objective.

»  What adverse effects could occur as a result of dose reduction actions?

Optimization of protection requires that exposure of patients be the minimum necessary to achieve the required diagnostic (BSS) and therapeutic objective of the interventional procedure. By no means should dose reduction compromise clinical information and outcome. If overlooked, the adverse effects may be quality and extent of information.