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Orthopaedic surgery often requires the use of C-arm machines to carry out surgery, the process due to the ionising radiation generated by the X-ray machine, not only on the patient’s body has an impact on the doctor likewise exists no small safety risks. Especially for doctors, long-term past may induce disease, so choose the brand of x-ray machine should be very careful.
In the usual surgery C-arm from the bulb tube issued by the ray into the body, 1% through the body into the intensifier, the remaining 80% to 90% of the ray is absorbed by the patient, 10% to 20% of the ray is scattered by the body.
Reduce the radiation of C-arm machine in surgery, in addition to the most basic time protection, distance protection and shielding protection of the three principles, there are some techniques to reduce the dose and scattered rays are worth sharing.
1、The tube under the bed when in orthostatic position
If the film is taken in the orthostatic position, the best way is to put the radiation emission source of the C-arm machine, i.e., the bulb tube, under the bed, and then separate from the operator with lead curtains and other protective devices, so that the scattered rays will basically be blocked.
2, C-arm receiver as close as possible to the shooting site
In the case of meeting the sterile requirements, the closer the receiver is to the patient, the more X-rays can be effectively received through the patient, and the corresponding bulb tube is farther away from the patient, the patient is subjected to less radiation, so that the quality of the film out of the film and high, but also so that the intensity of the emission is not too large. Magnification mode should be avoided for image size, as halving the field of view increases the dose rate up to four times.
3, the site of fluoroscopy aligned with the centre of the intensifier: if not aligned with the centre, it may lead to black imaging or even waste film.
4, image quality need not pursue perfection, can meet the needs of surgery. Because high-quality images must mean a higher dose of radiation.
5, different brands of machines may have their own personalised settings, such as continuous fluoroscopy frequency adjustment, voltage kV and current mA adjustment, LowDose mode selection; recommended that the operating theatre staff operating the C-arm machine to learn more about the operation of the machine, in order to meet the surgical needs of a smaller dose of radiation. Sometimes a 10-fold lower dose can be achieved with proper operation!
6, reduce continuous fluoroscopy, after the first exposure stabilisation, subsequent exposures using spot film or single pulse fluoroscopy can be; if you need continuous fluoroscopy can be used 4pps or 8pps discharge, try to avoid continuous discharge. Single pulse discharge (50ms pulse) and continuous discharge compared to the ray dose can be reduced to 5%, 4PPS discharge can be reduced to 20%, 8PPS discharge can be reduced to 40%.
7, other methods to reduce scattered rays: the use of beam limiter (Collimator) and removable filter grid and aluminium filter.
Filter grid is used to filter out stray rays to the detector, but at the same time will also absorb some of the useful rays resulting in an increase in dose, the thicker the patient’s lesion site, the more stray rays, the more the need for a filter grid. When operating on a child, the thinner the child’s torso is, the fewer stray rays there are, and removing the filter grid will not improve the image quality, but will reduce the radiation dose substantially, but the dose will be substantially reduced. Similarly, for extremity surgery in adults, the grids can be removed to reduce the dose.
C-arm machine manufacturers Perlove Medical, from the need to care for the health of doctors and patients, in a variety of C-arm products using the “pluggable filter grid” design. Such as the PLX119 series of dynamic flat C-arm machine, the device adopts a one-piece rack design, covers an area of only 1 square metre, to adapt to a variety of crowded and complex surgical environment. Pluggable filter grid design, combined with DAP dose monitoring system, easy to control radiation risk. In addition, it also has many other highlights such as power-off standby, touch operation screen, two-way laser positioning, automatic hovering and so on.
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