The Relationship Between Grey Levels And Hounsfield Units In Cone Beam CT ( CBCT ) Scanners

A focus on the equipment is most important as it relates to the human-machine interaction (we learnt about this in the HCI project in class, as well as in lab). That is to say, the need is not necessarily for more powerful x-rays but rather x-ray imaging that facilitates screeners’

Using CT (Toshiba Scanner Activio, Toshiba) for measurement and analysis image using the processing software (OsiriX, Newton Graphics) for calculated splenic

SPECT imaging produces a three-dimensional image that can be reconstructed into axial, coronal, and sagittal images (Radiological Society of North America, 2016). During the SPECT scan, the camera travels in an orbit around the patient acquiring images in multiple projections. These projections are then reconstructed by the computer into a two dimensional cross-sectional slice. This type of bone scan allows a particular body part to be imaged and examined in more detail due to the increase in sensitivity, as well as the improvement of 10 – 20 times more contrast when compared to a standard planar bone scan. SPECT can be done in addition to a whole body bone scan to obtain a more accurate diagnosis, without increasing the patient’s radiation dose (Zukotynski, Curtis, Grant, Micheli, & Treves,

The denser areas are shown as white while the soft areas appear dark in the film but sometimes some organs may block x-rays from showing broken or cracked bones and for this reason CAT (Computer Axial Tomography) was invented. Firstly, the person requiring the scan is put inside of a scanner, which is a long tube-shaped machine and then x-rayed from all angles, after a computer puts all of the images together so that doctors can analyse them. CAT are mainly used for head and brain injuries and appropriate shielded should be provided to cover the areas not being x-rayed.

Due to the various advancements of technologies in the field of radiography, sometimes it can be difficult to choose with imaging modality can be used to provided the best care for the patient and diagnose Clinicians must be aware of the potential benefits and drawbacks of each imaging modality to balance its use with healthcare costs, radiation dose to the patient, as well as patient safety.

Computed Tomography is more commonly known as a CT scan. This medical instrument uses x-ray radiation, which “combines multiple x-ray images into a 3D model of a region of interest,” (Lucas 1). The various organs in the body absorb x-rays differently. A computer monitors the process of absorption with “30,000 x-ray beams,” (Timberlake 171), that is directed at the organ being scanned, such as, the brain. An x-ray wavelength has two different types, a soft and hard x-ray. A soft x-ray wavelength ranges between “3x10^16 hertz to about 10^18 hertz,” (Lucas 1). On the other hand, hard x-rays range between “10^18 hertz to higher then 10^20 hertz, with a wavelength from 100 pm to about 1 pm,” (Lucas 1). CT scans give doctors specific information about their patient.

To review the principles of CT, first we need to know the physics basic of X-ray imaging. Attenuation, which is defined as the removal of X-ray photons from the beam, occurs in biologic

Visual inspection of the MRI image is used to determine intensity thresholds or the fatty, fibroglandular, and transition regions in the histogram of Fig. 2(b). The intensity at which the local peak occurs within the higher end of the intensity spectrum of Fig. 2(b) is mapped to the median Debye parameters chosen for fatty tissue. The maximum pixel intensity within this fatty region of the histogram is mapped to the minimum fatty tissue Debye parameters, and the minimum fatty tissue pixel intensity is mapped to the maximum fatty tissue Debye parameters. The same process is applied to the fibroglandular tissue region clustered at the lower end of the pixel intensity spectrum. Pixel intensities within the transition region are mapped to Debye parameters that span the range between the fatty maximum and fibroglandular minimum. Fig. 3(b) shows a histogram of the resulting dielectric constant at 6 GHz when the median Debye parameters are assigned the values listed in Table I for fatty and fibroglandular tissue and the variation about each of the two medians is chosen to be

“CT unit provide cross-sectional views of the body and is able to obtain several dozen images for information with one exposure”. (Gurley, Callaway, 2011, 87). In USA, first clinical trial of CT scan was conducted in 1973 by Mayo clinic. Current CT scanners generate very less radiation comparing to old units. They also have a capability to create 3D images. The new scanners are 320 slices and complete one 360° rotations in 275 milliseconds. Both contrast and non contrast studies are performed with CT. “The median effective radiation dose for non-contrast studies is 0.93 millisieverts (mSv) compared to 2.67 mSv for the first generation units”. (Yang, et al, 2014, 41). Depending on the facility the average cost of routine non contrast study is $850-$1500, and for contrast and any special procedure ranges from $2500-$6000. GE healthcare is also a major manufacturer of CT

The computed tomography (CT) scan is a procedure that uses x-rays and digital technology to construct conception of the body. It can make a reflection of every part of the body, for example bone and blood vessels.CT scans are used to examine the inner structures of the body which cannot be seen by human eye.Examples are blood cots or tumors.CT scan can also be used to measure precisely the density of bone in assess osteoporosis.

Medical imaging is one of the most beneficial discoveries made in this century since it has provided medical professional with the visualisation of the internal structure of human body. This visualisation is of great significants to the medical professionals in diagnostics and the treatment of diseases. Imaging is obtained by using a source such as X-ray, ultrasound, gamma ray photons and magnetic fields. Since these sources obtain radiations that can be harmful for the body, it is important that the doses are being reduced. Each individual imaging technique provides the professionals with specific set of information, however, the ability of them to illustrate the details differs from each other significantly. As a result, a detailed picture would provide the most beneficial information for diagnoses of patients.

CT scan is a computerized tomography, it is when slices of images are put together to make up a three-dimensional image of the body produced using an advanced x-ray. It is used to diagnose medical diseases. It has improved widely to provide comfort to patients as the scan can be done quickly. It displays high-resolution images assisting doctors to make diagnosis. For example, the CT scan can help doctors to visualize small nodules or tumors, which they cannot see with a plain film X-ray.

Since the evolution from conventional to digital radiography the radiation dose to patients have been significantly decreased.

X-Ray’s are used to generate pictures that show the inside of the human body such as finding broken bones. In Otto Zhou of the University of North Carolina, Dr Zhou and his colleagues are bringing X-radiography into the world of modern electronics. In doing so, there is a hope to create X-ray

Digital radiography (DR) is a revolutionary invention in radiography. With this technology, no cassette is needed for an x-ray examination meaning that there is no need to reload films or to erase imaging plate in every examination. This is a distinctive feature which conventional radiography and computed radiography (CR) do not have. DR was first introduced in 1996 (Carroll, 2011). Miniature electronic x-ray detectors are used as the image receptor. The detectors enable the direct capture of the x-ray image without conversion steps (like the conversion of x-ray photos into light photons). This technology is widely used nowadays since it has many advantages and it brings much convenience to radiographers. One of the main advantages of DR is image post-processing in which the quality of the film (in terms of contrast and brightness, etc.) can be adjusted to reach the desired standard. Therefore, the tolerance of the deviation of the exposure factors is greater and the need of repeating the examination is greatly reduced so the patient dose is reduced. This follows the as low as reasonably achievable principle for radiation protection and this also improve the final image quality simultaneously. Besides, many DR systems were installed with preset for numerous anatomical studies which can improve the post processing. Like CR, the images produced are in digital format so this provides convenience for radiographers to store and retrieve the image easily. DR is also capable to work with PACS