Assessment Of The Principles Of Operation For Mobile X-Ray Units And Image Intensifiers Within The Wards And Operating Theaters

INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Medical imaging is currently one of the routine and developing methods in medical diagnostics using advanced mobile and fixed imaging facilities. It is estimated to constitute about 30% to 50% of critical decisions in medical approaches (Abadi, 2010).Used equipment is frequently available from wealthier countries and is given to underserved areas.
This equipment usually is complex since it was designed to meet different clinical needs. Training and expertise to operate such X-ray systems are not available locally. In addition, power requirements are often heavy and there is no way to compensate for unreliable power supplies.
Mobile x-ray unit is often used by professionals who have mobile practices or in busy medical facilities where space is an issue or there’s a distinct lack of access to equipment.
This unit is used for radiographic imaging of patients who cannot be moved to the radiology department and who are in areas—such as intensive and critical care units or operating and emergency rooms—that lack standard, fixed radiographic equipment. Medical applications can include general radiography and orthopedic, pediatric, skeletal, and abdominal imaging.
The image intensifier is comprised of a large cylindrical, tapered tube with several internal structures in which an incident x-ray distribution is converted into a corresponding light image of non-limiting brightness. A picture of an image intensifier television (II-TV) system is shown below. X-ray to light amplification is achieved in several sequential steps. First, x-rays incident on and absorbed by a cesium iodide (CsI) structured phosphor produce a large number of light photons resulting from the energy difference of x-rays (30-50 keV average) to light photons (1 -3 eV average). Absorption and conversion efficiency is on the order of 60% and 10%, respectively. A fraction of the light photons interact with an adjacent photocathode layered on the backside of the input phosphor, releasing a proportional number of electrons (typically on the order of 5 light photons / electron). Being negatively charged, the electrons are accelerated through a potential difference of approximately 25,000 volts towards the positive anode positioned on the tapered side of the evacuated tube. Electro-magnetic focusing grids maintain focus and at the same time minify the electron distribution as it interacts at the output phosphor structure, producing a large increase in the light intensity compared to the amount of light originally produced at the input phosphor. Overall brightness gain of the II is achieved through the acceleration and kinetic energy increase of the electrons impacting on the output phosphor (known as electronic or flux gain) as well as the geometric area reduction of the electron density from the large area input phosphor to the small area output phosphor (known as magnification gain, equal to the ratio of the input to output phosphor areas, or ratio of the square of the diameters). The combination of electronic and magnification gain results on the order of 5000X increase in brightness. Variable brightness gain occurs with a change in the input phosphor active area; as the field of view (FOV) is reduced, the magnification gain is reduced, decreasing the overall brightness gain (and vice-versa). Optical coupling of the output phosphor to a TV camera or photospot, cine, or other light detector allows the detection of the image and subsequent display.

1.2 PROBLEM STATEMENT
The evolutional trend of radiography from conventional to computed, is a laudable development in the radiography practice however , many centers within the country still practice conventional radiography , which appears to be old- fashioned in developed countries today. The need for facilities to upgrade from conventional (fixed) to mobile is hinged on the benefits of quality services. Many of the radiological centers in the country, just as it is in many third world countries, still operate very old, near obsolete X-ray machines (Eze et al, 2013). Regrettably, equipment Quality Assurance (QA) programmes are barely practiced, in the country, as a number of studies have demonstrated (Inyang et al, 2010). However, there is also the challenge of poor operation of the X-ray machines due to scarcity of Medical Physicists and Radiation Safety Officers (RSO) whose responsibility it is to establish QA programmes that will ensure optimum performance of x-ray machines and maximize patient safety.
This study was carried out to assessment of the principles of operation for mobile x-ray units and image intensifiers within the wards and operating theatres

1.3 AIM AND OBJECTIVES OF THE STUDY
This study is therefore aimed at assessing the principles of operation for mobile x-ray units and image intensifiers and evaluating the state of x-ray equipment in radiological facilities in Benin City. The objectives of the study are:
i. To determine the acceptance of mobile x-ray units and image intensifiers within the wards and operating theatres
ii. To assess the quality operation of mobile x-ray units and image intensifiers within the wards and operating theatres
iii. To determine the usage of mobile x-ray units and image intensifiers within the wards and operating theatres

1.4 SIGNIFICANCE OF THE STUDY
This study is important in that it helps in changing the attitude and knowledge Medical Physicists and Radiation Safety Officers (RSO) towards the operation of mobile x-ray units and image intensifiers within the wards and operating theatres. To identify the importance of having these machines in hospital walls and theatres.

1.5 LIMITATION OF THE STUDY
There are many other machines used in hospital walls and operating theatres, but this particular work is limited to assessing the operating principle of mobile x-ray units and image intensifiers within the wards and operating theatres

1.6 SCOPE OF THE STUDY
This study was adopted qualitative methodology of literature review, where previous studies data was considered from the theoretical background and analysis was drawn according to the researchers’ quest.

1.7 RESEARCH QUESTIONS
At the end of this project, answers to the following questions shall be provided:
i. What is mobile X-ray units?
ii. What is an image intensifier?
iii. What is the operation of mobile X-ray machines?
iv. What is the difference between mobile X-ray and image intensifier?

1.8 DEFINITION OF TERMS
Radiograph —An image formed on a radiographic plate (similar to the film in a camera) by x rays. This is the final image produced by an x-ray unit.
Tracer —A chemical that is relatively dense to x rays that is added to the body to make that part of the body imagable with x rays. Examples include barium, used to image the gastrointestinal tract, and iodine, used to image blood vessels. Without the use of a tracer, these structures would be difficult, or impossible, to differentiate from surrounding tissues.
X ray —An invisible form of light that has a wavelength that is much smaller than visible light and a frequency that is much faster than visible light. Because of these properties of x rays, they can be used to image dense structures within the human body.