extra chapter 7

Question 1

1) What are the two components of beam restriction? How are each of them important?

Answer 1

• kilovoltage
• irradiated material

Question 2

2) What are the common beam-limiting devices?

Answer 2

• diaphragms
• cones
• collimator

Question 3

3) What is the purpose of x-ray beam filtration?

Answer 3

• The purpose of x-ray beam filtration is to absorbed low energy photons from exiting the tube to reduce patient dose

Question 4

4) Explain inherent filtration, added filtration and total filtration?

Answer 4

inherent - consists of the glass window of the X-ray tube and the cooling oil surrounding the tube housing

added - consists of aluminum or aluminum equivalent (Al eq.) of appropriate thick- ness inserted outside the glass window of the tube housing.

total - The combination of inherent filtration plus added filtration

Question 5

5) What is the minimum Al/Eq for filtration above 70 kVp?

Answer 5

2.5 mm AL EQ

Question 6

6) What are the 3 types of gonad shields? When should they be employed?

Answer 6

• Flat contact shield
  > Used in recumbent studies
• Shadow shields
  > Used in sterile fields (operating room)
• Shaped contact shields
  > Male patients
  > Used when doing oblique, lateral, and erect studies

Question 7

7) Describe how exposure techniques can be used to influence patient dose.

Answer 7

• With kVp, it is desired to have a low setting, as it deals with quantity. kVp also has a direct relationship with exposure.
• The higher the kVp, the higher the patient dose
• mAs deals with quality, having a direct relationship with density and exposure
• The minimum patient dose is a high kVp with a low mAs
• As long as the settings balance themselves out to maintain a radiographic balance, having a high kVp or vice versa is acceptable (technique settings also depends on the part being examined)

Question 8

8) Why is patient positioning important in reducing patient dose?

Answer 8

• With the correct positioning, it will allow the radiographer to produce a high quality image.
• With all the correct angles, it can be observed once dealt with by the doctor.
• With correct positioning, there are no mistakes, thus reducing retakes and reducing patient dose

Question 9

9) Why is it important for a technologist to always ask their female patients of child-bearing age whether they are pregnant?

Answer 9

• It is important to make sure the patient is not pregnant to avoid high exposure radiations during exams
• When pregnant, safety procedures need to be made to keep the fetus safe from radiation.

Question 10

10) Give examples of some causes of repeat radiographs and how to avoid them.

Answer 10

• Incorrect positioning
• Processor artifacts
• Dirty screens
• Chemical fog
• Grid errors