23-09-21 - Introduction to Medical Imaging Flashcards
1
Q
Define radiology
A
- A branch of medicine concerned with the use of radiant energy (such as x-rays) or radioactive material in the diagnosis and treatment of disease
2
Q
What is the different medical imagine techniques?
A
- Conventional x-ray
- Computer tomography (CT)
- Nuclear medicine
- Magnetic resonance imaging (MRI)
- Ultrasound imaging
3
Q
How do x-rays/radiographs work?
A
- As a beam of x-ray passes through the body, some of the x-rays are absorbed or scattered, producing reduction or attenuation of the beam
- Tissues of high density and or high atomic number cause more x-ray beam attenuation and are shower as lighter grey or white on a radiograph
- Tissues of lower density cause less attenuation of the x-ray beam, and appear darker on radiographs.
4
Q
What are the 5 x-ray densities?
A
- Low density material like air appears black on x-rays
- High density material, like metal, appear white on x-rays
- Body tissues appear grey
- Fat is the darkest shade of grey, followed by soft tissue, then bone as the lightest tissue on x-rays
5
Q
What is mammography?
What is it used for?
A
- Mammography is a specific type of x-ray imaging that uses a low dose x-ray system that is designed for creating detailed images of the breast
- Mammography is used either as a screening tool to detect early breast cancer in women without symptoms, or to diagnose a breast disease in women with symptoms, like a lump.
6
Q
What is fluoroscopy?
What is it used for?
A
- Type of medical imaging that shows a continuous x-ray imagine on a monitor
- Used so the movement of a body part, or the movement of an instrument or contrast agent (x-ray dye) through the body can be seen in detail.
7
Q
How does fluoroscopy work?
When is it used?
A
- As with conventional x-ray, an x-ray is passed through the body, but instead of being registered on film, the image is displayed on a fluorescent screen
- The image is then intensified digitally and displayed on a screen or recorded for more detailed analysis later
- Used where real-time examinations of the patient’s body is required, such as orthopaedic implants during surgery.
8
Q
What is angiography?
When is it used?
A
- Angiography is an x-ray technique used in the examinations of arteries, veins and organs to diagnose blockages
- A substance called a contrast agent is injected to make blood vessels visible on the x-ray image
9
Q
What are some advantages and disadvantages of x-rays?
A
- Advantages
- Cheaper and simpler technique
- Lower radiation compared to CT
- Helps diagnose tumours easily without the need for surgery
- Disadvantages
- It does not provide 3D information
- It only produces a medium quality image
- Due to the ionizing radiation, it can mutate DNA, which can often lead to cancer.
10
Q
What is tomography?
How are tomographic images made?
A
- Tomography is the methods that produces images of a single plane of tissue
- Tomographic images are produces by the motion of the x-ray tube and film or by motion of the patient that blurs the image except in a single plane.
11
Q
What is a CT scan?
A
- CT scans (also called cat scans (axial)) are Computerized tomography scans
- It is a radiologic imaging method that uses computer processing to generate an image of the tissue density in a slice as thick as 1mm through the patient’s body, like slices in a load of bread
- This is known as cross-sectional imaging
12
Q
Advantages and disadvantages of CT scan
A
- Advantages
- Painless, non-invasive, accurate
- Ability to images bones, soft-tissue, and blood vessels at the same time
- Provides detailed images of many types of tissue and organs
- Disadvantages
- Use x-rays, which utilize ionizing radiation. This can lead to mutations of DNA and cancer
- The need for use of a contract dye in most cases might make it inappropriate for patients with significant kidney problems.
- Can’t image soft tissue like the brain or spinal cord very well.
13
Q
What is scintigraphy nuclear medicine?
What is a PET scan?
A
- Scintigraphy refers to the use of gamma radiation to form images following the injecting of various radiopharmaceuticals.
- Positron emission tomography is a combination between CT and Scintillation scanning mostly used in oncology
- PET utilizes radionuclides that decay by positron emission
14
Q
What are the advantages and disadvantages of nuclear medicine imaging techniques?
A
- Advantages
- Less expensive, and may yield more precise information than exploratory surgery
- Can identify disease in its earliest stage before symptoms occur.
- Great accuracy, which can make complex procedures simpler.
- Disadvantages
- High operating cost
- Exposes patients to gamma radiation
15
Q
How do MRI scans work?
A
- MRI systems use a powerful magnetic field and radiofrequency pulses to produces detailed images of the body’s internal structures as cross-sectional images/slices
16
Q
What are the advantages and disadvantages of MRI scans?
A
- Advantages
- Does not use radiation
- Better soft tissue contrast than CT
- Can differentiate between fat, water, and muscle
- Disadvantages
- The effect of the magnetic field on metal devices in the body.
- Claustrophobia and difficult fitting in small space of MRI.
- Expensive.
17
Q
How do ultra-sounds work?
A
- An ultrasound scan (also called a sonogram) is a procedure that uses high-frequency sound waves to create an image of part of the inside of the body
18
Q
What are the advantages and disadvantages of an ultra-sound?
A
- Advantages
- Ultrasound is safe
- No ionizing radiation
- Equipment is portable, compact, and relatively cheap
- Disadvantages
- Highly operator dependent
- Structures surrounded by bone don’t give clinically useful images, such as brain and spinal cord
- The attenuation of ultrasound signal at air/tissue boundaries mean it is not suitable for imaging the lungs or abdominal organs
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