Radiographic technologies

Radiographic technologies

Section A

Q1. With reference to Magnetic Resonance Scanner, explain how magnetism and radio frequency waves are used to acquire an image of the internal anatomical structures of a patient. Comment on which type of tissue this imaging method is best suited.

Magnetic Resonance Imaging, also known as MRI is a technique of medical imaging that is used in radiology for the visualization of bodily structures in detail. It is also known as Nuclear Magnetic Imaging (NMI) or Nuclear Magnetic Resonance Imaging (NMRI). It is a form of tomography just like CT Scanning. The general idea is to capture images of the atoms making up the human body using X-rays (Novelline, 1997).

The process is simple. The patient lies in a large and powerful magnet and the magnetic field is used for aligning the atomic nuclei of the patient's body. At the same time, radio frequency is used to alter the alignment of the magnetization caused by the magnetic field. This makes the nuclei of the body produce a rotating magnetic field of its own. This field is detected by the scanner and recorded in the form of an image. In this way, an image is formed of the scanned area of the patient's body. The magnetic field of the scanner can be adjusted to different gradients, causing the nuclei of the body to rotate at various speeds. Additionally, the direction of the nuclei can also be controlled to obtain 3D images of the body.

The working principle of an MRI scanner includes the clash of a magnetic field and a radio frequency and the impact of this clash on a human body's tissue. Human tissues contain lots of water and using this technology, the protons in that water can be aligned to generate the images.

This imaging method is best suited for soft tissues of the human body. It is highly useful for capturing images of the human brain, muscles and heart. Additionally, it is also quite useful for capturing images of cancer infected parts of a human body.

Q2. With reference to a computer tomography scanner explain the basic principles of generating multiple cross sectional digital images.

Computerized Tomography is also commonly known as 'Computed Tomography' (CT) or X-ray computed tomography. It is a procedure that is commonly used for imaging and various methods of tomography involving computer processing. The medical name for the procedure is 'Computed Axial Tomography' (CAT Scanning). Using digital geometric processing, a three-dimensional (3D) image is generated. This image is generated by the combination of a large series of two-dimensional (2D) images. These two-dimensional (2D) X-ray images are taken around one singular rotational axis (Herman, 2009).

Using a process known as 'windowing', CT Scanning produces a huge volume of data that can easily be manipulated. The process of windowing allows various bodily structures to be observed and identified based on their capability to block X-ray beams. Initially, the images were generated in planes (axial or transverse) which were perpendicular to the vertical axis of a human body but recently developed modern ...