FREE RADIOLOGY AND STUDY GAMES ABOUT GRIDS

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FREE RADIOLOGY AND STUDY GAMES ABOUT GRIDS

EXAM QUESTIONS

Actual Qs and Ans Expert-Verified Explanation

This Exam contains:

-Guarantee passing score -72 Questions and Answers -format set of multiple-choice -Expert-Verified Explanation

Question 1: Undesirable absorption of primary x rays by the grid.

Answer:

Grid cutoff Question 2: With increased frequency do you get more or less dose to patient? Do you have to use more or less technique?

Answer:

more dosemore technique

Question 3: Upside down grid

Answer:

least common;a radiographic image is taken with an upside down focused grid shows sever grid cutoff on either side of the central ray

Question 4: What is the moire effect?

Answer:

It is a zebra pattern that shows when you use tooo low a frequency grid with electronic imaging or a grid is put into a bucky

Question 5: What are two disadvantages of using cross grids?

Answer:

Must position correctly so the x ray beam coincides with the center of the grid and if table and tube are not aligned properly you will get grid cutoff

Question 6: what is the formula for grid ratio?

Answer:

Grid Ratio= H/D

Question 7: How do the focused grid lead strips lie?

Answer:

They coincide with the divergence of the beam.

Question 8: What is the air gap technique?

Answer:

IR is moved 10-15 cm from pt. Portion of x rays are scattered away from IR contrast (mAs is increased approx. 10% for every cm of air gap)

Question 9: What is the formula for Selectivity?

Answer:

Greek sigma = primary radiation transmitted through grid/ scatter radiation tansmitted through grid Question 10: Higher ratio grids are not as effective as low ratio grids in cleaning up of scatter.T/F

Answer:

False - Higher ratio grids are better at cleaning up scatter due to the angle of deviation being smaller

Question 11: What is the formula for grid frequency?

Answer:

grid frequency= 10,000 um/cm /(T+D) um/line pair

Question 12: The number of grid strips or grid lines per ich or centimeter

Answer:

Grid Frequency

Question 13: Oscillating grids

Answer:

positioned in a frame , a powerful electromagnet pulls the grid to one side and releases it at the beginning of the exposure, and oscillates in a circular fashion

Question 14: what is the formula for the contrast improvement factor (k)?

Answer:

k= radiographic contrast with grid / radiographic contrast without a grid

Question 15: Moving grids

Answer:

movement of the grid while the x-ray exposure is being made. the grid lines disappear and less increase of technique.

Question 16: Grids are made of ________.

Answer:

Alternating radiopaque material (lead- grid strips) and radiolucent material (aluminum or plastic - interspace material.Question 17: Lead grid strips running parallel to both the long and short axes of the grid

Answer:

Crossed grid

Question 18: What are grid lines?

Answer:

They are images made when primary x rays are absorbed in the grid strips.

Question 19: What technique can we use in place of grids?

Answer:

Air gap technique

Question 20: What are four types of problems that can occur with focused grids?

Answer:

off-level, off-centered, off-focus, upside-down

Question 21: In the air gap technique does air act as a filter?

Answer:

No, it does not act as a filter. The scattered x rays diverge from the IR due to the distance between the patient and IR.

Question 22: what is the purpose of the interspace material?

Answer:

to maintain a precise separation between the delicate lead strips of the grid.

Question 23: Which grid is designed to minimize grid cutoff?

Answer:

Focused grids

Question 24: what is the k range?

Answer:

1.5-2.5 (radiographic contrast is doubled when grids are used; a k of 1 indicates no improvement)

Question 25: what is the formula for Bucky factor?

Answer:

incident remnan radiation/ transmitted image - forming radiation = patient dose with grid/ patient dose without grid Question 26: For diagnostic kVp range the highest quantity is at ______ to patient. (backscatter)

Answer:

180 degrees

Question 27: What two materials can the interspace be made of?

Answer:

aluminum or plastic

Question 28: What are some disadvantages to using a grid?

Answer:

Increase in patient dose and increased technique