Medical Interventions 3.1

• Cancer cells are abnormal cells in which the processes that regulate normal cell division are damaged
• Personal actions such as smoking, alcohol consumption, sun exposure, and diet can increase the risk of cancer.
• Cancer can affect any tissue in the body
• Early detection and treatment leads to better prognosis and survival rates for patients with cancer
• Cancer can spread/metastasize to other parts of the body
• Incidence of cancer increases with age
• Cancer is diagnosed by medical tests such as X-rays, CT scans, and MRI scans
• X-rays are a noninvasive medical test used to produce images of the inside of the body to help diagnose medical conditions
• X-rays are a form of electromagnetic radiation that is sent though the body in the form of photons
• Rays from x-rays easily pass through soft tissues but are absorbed by hard tissues like bones
• Why do we use x-rays for bones?

  When the rays pass through the soft tissues, the x-ray film does not capture them but it does capture bones because the rays are absorbed
• In x-rays, less dense structures appear black or dark gray while more dense structures appear gray to white.
• Advantages of X-rays are:

  1. Quick, painless, noninvasive test
  2. Relatively inexpensive
• Disadvantages of X-rays

  1. Small amounts of radiation exposure
  2. Contract materials sometimes used might produce an allergic reaction
• The CT scan is also called the Computerized (Axial) Tomography (CAT Scan)
• True or false: CT scans are a specialized type of X-ray 


  True
• True or false: X-rays are two dimensional


  True
• Advantages of CT scans:

  1. Painless, noninvasive, and accurate test that is fast and simple
  2. Able to image bone, soft tissue, and blood vessels all at the same time
  3. Can be performed if patient has an implanted medical device of any kind
• Disadvantages of CT scans:

  1. Small amount of ionizing radiation exposure
  2. Contrast materials sometimes used might produce an allergic reaction
• CT scans consist of a series of X-ray views taken from many different angles which are then combined to produce cross-sectional images of the bones and soft tissues inside your body
• In X-rays, structures containing air will appear black but muscle, fat and fluid will appear gray
• X-rays mainly examine bones, teeth, lungs, breasts, heart, blood vessels and the digestive tract
• CT scans produce cross-sectional images of the body
• CT scans examine the chest, abdomen, pelvis, spine and other skeletal structures
• CT scans are performed inside a large tube and The person lies on the table in the center. The X-ray tube rotates around the body and the table slowly moves through the inside of the machine. Each rotation yields several images of thin slices of the body.
• MRI is also known as Magnetic Resonance Imaging
• MRI uses powerful magnets and radio waves not radiation like X-rays and CT scans
• MRIs produce detailed images of soft tissue
• CT scans are more sensitive than X-rays and can be used to detect disease in the soft body tissues
• MRIs are used to examine the brain, spine, joints, abdomen, blood vessels and pelvus
• MRIs are not harmful unless a person has certain types of metal implanted into their body
• MRI scan is performed inside a large magnet, and the machine scans the body by turning small magnets on and off. Radio waves are sent into the body and the machine then receives returning radio waves and used a computer to create pictures of the body part being scanned
• Advantages of MRI

  1. Noninvasive test that poses almost no risk when safety guidelines are followed
  2. does not involve exposure to ionizing radiation
  3. Images of the soft tissue structures of the bdoy are more likely to identify and accurately characterize diseases that other imaging methods
  4. Contrast materials sometimes used less likely to produce an allergic reaction that those used in X-rays and CT scans
• Disadvantages of MRI

  1. Implanted medical devices that contain metal may malfunction or cause problems during an MRI exam
  2. Very slight risk of an allergic reaction if contrast material is injected
  3. Confined space may induce panic or feelings of claustrophobia in some patients
• Bone scan is a nuclear imaging test
• Advantages of bone scan

  1. Noninvasive
  2. Extremely sensitive to abnormalities and variations in bone metabolism
  3. Can scan the entire skeleton
• Disadvantages of bone scans

  1. Cannot determine cause of bone metabolism abnormalities
  2. Tracers used produce a small amount of radiation exposure
• Bone scans start with an injection of tracers being administered to the patient and allowed to circulate and be absorbed to the bones
• After the tracers are absorbed in bone scans, the patient lies in a table while a machine passes a gamma camera over the body to record the pattern of tracer absorption by the bones
• In bone scans, radiologists look for abnormal bone metabolism on the scan; areas that show up as darker or lighter where tracers have or have not accumulated