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Questions and Answers

What is the appearance of subcutaneous tissue layer in an X-ray image?

Off-white

Bright white

Dark grey (correct)

Light grey

What determines the brightness of an ultrasound image?

The degree of reflection of ultrasound waves (correct)

The shape of the structure

The position of the structure

The size of the structure

What is the purpose of analyzing a structure in a medical image?

To determine the patient's weight

To identify the patient's medical history

To analyze the structure's size, shape, and position (correct)

To determine the patient's age

What is the term for the brightness of an ultrasound image?

Echogenicity Signup and view all the answers

What happens to X-rays as they pass through the body?

They are blocked by higher atomic number structures Signup and view all the answers

What is the term for the reemitted radio signals in MRI?

Reemitted signals Signup and view all the answers

What is the purpose of a multichannel phase array coil in MRI?

To capture reemitted radio signals Signup and view all the answers

What determines the ability of a structure to block X-rays?

Its atomic number Signup and view all the answers

What is the term for a structure that reflects ultrasound waves strongly?

Hyperechoic Signup and view all the answers

What is the term for a structure that does not reflect ultrasound waves?

Anechoic Signup and view all the answers

What is the primary purpose of radiographic imaging?

To identify pathologic conditions Signup and view all the answers

What determines the gray scale of a radiograph?

The energy of the X-ray and the atomic number of the tissue Signup and view all the answers

What happens to X-rays when they pass through the body with the greatest degree?

They pass through the body to the film Signup and view all the answers

What is the relationship between the energy of the X-ray and its ability to pass through the body?

Higher energy X-rays are more likely to pass through Signup and view all the answers

What is the effect of air on a radiograph?

It appears black on the radiograph Signup and view all the answers

What is the order of increasing density on a plain radiograph?

Air, Fat, Soft tissue, Bone, Metal Signup and view all the answers

What is the purpose of the X-ray tube in medical imaging?

To produce X-rays Signup and view all the answers

What happens to X-rays that are totally blocked by the body?

They do not reach the film and render it light (white) Signup and view all the answers

What is the relationship between the atomic number of a tissue and its ability to absorb X-rays?

Higher atomic number tissues are more likely to absorb X-rays Signup and view all the answers

What is the result of X-rays passing through the body to the film?

The film appears dark (black) Signup and view all the answers

Study Notes

X-Ray Imaging

X-rays are a form of electromagnetic energy that travel at the speed of light.
X-rays can pass through, be deflected or scattered, or be absorbed by the body.

How X-Rays Create an Image

X-rays that pass through the body to the film render it dark (black).
X-rays that are totally blocked do not reach the film and render it light (white).
The gray scale of the radiograph depends on the energy of the x-ray and the atomic number of the tissue.

Radiographic Densities

The five basic radiographic densities are:
- Air/gas: black
- Fat: dark grey
- Soft tissues/water: light grey
- Bone: off-white
- Contrast material/metal: bright white

Analyzing Structures

Any structure, normal or pathologic, should be analyzed for:
- Size
- Shape and contour
- Position
- Density (knowing the 5 basic densities)

X-Ray Absorption

Higher atomic number structures block x-rays better, e.g. bone.
Lower atomic number structures allow x-rays to pass through, e.g. air in the lungs.

Ultrasound Imaging

Interpretation of ultrasound images depends on echogenicity: the brightness of the image depending on the degree of reflection of the ultrasound waves.
Terms used include hyperechoic, isoechoic, hypoechoic, and anechoic.
Images are described in terms of the plane on which the sonogram is viewed, usually longitudinal or transverse in relation to the structure scanned.

MRI (Magnetic Resonance Imaging)

Certain nuclei in the body will absorb and reemit radio waves of specific frequencies when under the influence of a magnetic field.
Reemitted radio signals contain information about the patient that is captured by a receiver or antenna.

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