Imaging Interpretation

Question 1

What are the advantages of X-ray’s?

What are the disadvantages?

Answer 1

• Relatively inexpensive
• Can be obtained almost anywhere (protable machine)
• Easily available
• Noninvasive
• Are the most widely obtained imaging study

Limited range of densities it can demonstrate, uses ionizing radiation

Question 2

What material appears black on X-Ray because it is very low density?

What appears whitest on x-ray?

Answer 2

Air

Metal (absorbs all the ionization)

Question 3

What are the biological effects of radiation?

Answer 3

• Directly damages molecules
• Indirectly creates free radicals to disrupt cellular metabolism

Question 4

Damage occurs when the level of radiation-induced cell damage _________ the cell’s ability to repair the damage.

Answer 4

Exceeds

Question 5

Why are children at a higher risk of mortality due to radiation-induced cancer than adults?

Answer 5

• Increased organ sensitivity
• Longer life expectancy and thus a longer latent period to develop cancer

The use of ionizing radiation in pediatric populations should be monitored carefully and utilized only when necessary. US and MRI should be employed when possible.

Question 6

What is the standard position for an adult chest x-ray?

Answer 6

Posterior-Anterior (PA) CXR

Question 7

How dose contrast work?

Answer 7

• Contains a high concentration of iodine (which has high radiodensity)
• Circulates through bloodstream, opacifying tissues and organs with high blood flow
• Which is then absorbed by x-ray (and therefore appear “whiter” on images)
• And is finally excreted in the urine by the kidneys

Question 8

What creatinine level increases the risk of a nephrotoxic effect, resulting in acute tubular necrosis with contrast?

Answer 8

> 1.5

DM, dehydration, multiple myeloma, and renal disease use caution w/contr

Question 9

What are the advantages of CT?

Answer 9

• Ability to expand the gray scale (which enables differentiation of many more than the 5 basic densities on plain films)
• Very fast imaging (due to the hundreds of slices obtained simultaneously)
• Allow for cross-sectional imaging

Question 10

What are the disadvantages of CT?

Answer 10

• Requires a scanner, a space dedicated to its installation, and sophisticated computer processing power
• Utilize ionizing radiation (x-rays) to produce images (just like conventional radiographs do)

Question 11

In an ultrasound, what happens when the sound waves encounter a highly dense structure or solid organ?

Answer 11

Most of the energy will be transmitted and not returned –> thus, appears darker gray on the screen (hypoechoic)

Question 12

What happens in an ultrasound when the sound waves encounter air, fat, or bone?

Answer 12

Most of the energy is either deflected or “echoed” –> appears as lighter gray to white shading on the image (hyperechoic)

Question 13

What color is fluid on US?

Answer 13

Black (anechoic)

Question 14

What are the advantages to ultrasound?

Answer 14

• US scanners are relatively inexpensive (compared to CT or MRI)
• Widely available
• Portable
• No ionizing radiation (good for pregnant women, kids)

Question 15

What are disadvantages of ultrasound?

Answer 15

• Difficulty penetrating through bone
• Penetration may be difficult in obese patients
• Dependent on the skills of the operator doing the scanning