Shua Darwish Almutawa 200023791 4MI

Term of reference:

This report is written as part of my Radiation Science II IMGE250 and Health Communications II ENGL256 courses. It is about one of the imaging modality that is mostly used to examine the patient in the emergency department or in the operating theater. This report is talking about three different types of mobile x-ray machines.

Mobile equipment:

Mobile x-ray equipment is the equipment that is used to examine the patients in wards and operating theatre. The use of this equipment should be limited to only the cases where the patient cannot be transferred to the x-ray department, because the mobile equipment is not as powerful as the one in the x-ray department. Mobile radiography is usually limited to chest radiography with some abdominal x-rays, examinations of other anatomical areas can be done but only in the cases when the patient cannot come to the x-ray department. The mobile x-ray machine should be: powerful enough to provide examination exposure within moderately short exposure times, and a wide range of exposure parameters. It also needs be maneuverable and adequate power supply. Not to forget that it is important to have an x-ray tube mounting that allows easy and varied movements to allow for accurate centering. There are three types of mobile x-ray machines: 1. Single phase full wave rectified generators 2. Constant potential generators 3. Capacitor discharge units

Single-phase full wave rectified generators: This type of mobile x-ray machine is operating as a single-phase generator powered by the hospital mains supply. X-ray exposures

1 Shua Darwish Almutawa 200023791 4MI draw a lager current from the power supply and especially when short exposures are needed. To provide the power needed for the exposures, the hospital plug socket, which is going to be used by the mobile x-ray machine, should be rated at 30 Amps. The power available to the machine dependent on the distance the machine is used from the power supply. The cables will be longer as the distance increasing from the power supply. The cables have resistance that is proportional to the cables length, and the power loss in a cable is I2R. This type of machine cannot cope with variations in the main supply, which may occur during the x-ray exposure.

Constant potential generators: There are two types of constant potential generators used in mobile x-ray equipment. The first type of machine powered by batteries. This type of machine uses Nickel-Cadmium batteries to provide the power for the x-ray exposures. These batteries can store about 10,000 mAs at normal operating voltages. These batteries provide a direct current (DC) of about 130V; the direct current will then be converted to an alternating current to be used to supply the high-tension transformer. An inverter carries out the conversion from direct current to alternating current. This machine has high frequencies the high- tension transformer works much more efficiently. The Nickel Cadmium batteries can be recharged from a normal 13 Amp mains supply using low current. The second type of constant potential mobile machine is a complicated design. The charge for the exposure is stored on a capacitor. This charge is used as a direct current supply to an inverter

2 Shua Darwish Almutawa 200023791 4MI producing a 4.5 kHz supply for the x-ray generator. The large capacitor can be charged from a normal 13 Amp mains supply.

Capacitor discharge units: In the capacitor discharge units machines a capacitor is used in a very different way from the capacitors in constant potential mobile machines. In the capacitor discharge machines the capacitor is connected directly to a grid controlled x-ray tube. To provide very rapid and accurate exposure timing the grid control should be turned on and off instantly. The capacitor can be charged at low current from a normal 13 Amp mains supply. At the start of the exposure the KVp of the capacitor is high, and relatively low at the end of the exposure, because the output falls as the exposure continues. To help with setting the exposures the equivalent exposures are calculated using the simple rule of thumb. The equivalent exposure is the exposure that would be needed on a constant potential machine and it is calculated by the following method: Equivalent KVp = starting voltage – mAs/3 It is important to understand the equivalent KVp when using capacitor discharge units, especially when exposures need to be changed due to the over or under exposure, but it is difficult to understand it or calculate new exposure for lager or even small patients and that what made this mobile equipment unpopular with some radiographers. The capacitor discharge unit needs more operators training to produce the best functioning.

3 Shua Darwish Almutawa 200023791 4MI

Modern x-ray mobile equipment:

Xport mobile X-Ray transport system is one of the modern x-ray machines. Xport is the first portable X-Ray system to be designed as a fully integrated compact transportation system for providers of mobile X-Ray. It is lightweight and well balanced for easy portability.

Conclusion: To sum up this report, I found that it is important to have a mobile x-ray machine in the hospital because as you see in the report there is some patient who is unable to come to the x-ray department and they need to be x-rayed. I found that there are different types of x-ray mobile machines and it is important to know the different between each type.

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