PATIENT RADIATION DOSE IN FLUOROSCOPY

PATIENT RADIATION DOSE IN FLUOROSCOPY

Fluoroscopy imaging time is higher and it may vary from 1–3 minutes for a examination to 15 minutes for a interventional procedure. Therefore, the radiation dose is higher for both patient and the operator. Hence, the skin entrance dose should not exceed 50 mGy/min to the patient. It will vary with kVp and patient thickness. Higher the kVp and lesser the patient thickness, lesser the radiation dose to the patient. A typical fluoroscopy examination may give a dose of 10–30 mGy/min. A procedure with 1 minute screening, at the rate of 50 mGy/min dose rate is equal to 15 pelvis radiographs.

 Dose reduction to the patient may be achieved by the following:

1.Heavy X-ray beam filtration.

2.Use of low frame rate pulsed fluoroscopy.

3.Use of lower-dose ABC options.

4.Last-frame-hold features.

5.Application of high kV.

6.Frame averaging.

7.Using the largest field of view suitable to a given clinical study.

The X-ray beam passing through the II tube is heavily filtered by 1.5 Al window. The fluoroscopy dose rate depends upon the quantum detection efficiency (QDE) of the II tube, which is kVp dependent. For II tube with CsI output window, the QDE is about 65% and it is maximum at 60 kVp. Hence, use of higher kVp > 60 is recommended. This will reduce patient dose drastically.

The occupational exposure of physicians, nurses, technologists, and other personnel who routinely work in fluoroscopic suites can be high.

 Hence,they should adhere the following:

1. Lead aprons should be worn when the X-ray beam is on.

2. Portable lead glass shields should be available for additional protection to staff members observing or otherwise participating in the procedure.

3. Reducing total fluoroscopy time is beneficial to everyone.