exposures II Test 2: xray production, rectification, generators, and filtration

How much of the tube currents kinetic energy is used for xray production?

0.5%

How much of the tube currents kinetic energy is converted to heat?

99.5%

The minimum total filtration in diagnostic X-rays must equal

2.5 mm aluminum

Which of the following falls in the usual range of inherent filtration equivalencies?

1.5 mm aluminum

Which of the following falls in the usual range of added filtration?

1.0 mm aluminum

Which of the following HVLs represents the lowest energy beam?

1.0 mm Al. Eq.

As more filtration is added in the path of the xray beam, ______

• more of the soft xray photons are absorbed

• The xray beam is hardened

• The average photon energy is increased

• Exposure latitude is increased

Added filtration is comprised of _______

Thin slabs of Al. Placed in the beam through a slot in the side of the collimator

When used in normal amounts, filtration alters the ______ beam, but doesn’t affect the ______ beam appreciably

Primary, remnant

Pocket ion chambers (and sleeve filters) can be used to determine a beams _________

• kVp

• mAs

• Penetration characteristics

Filtration serves to ______

• reduce patient dose

• Remove non diagnostic low energy photons from the primary beam

Total filtration in all modern xray equipment is equal to_____

Added filtration + inherent filtration

Rectification is ______

Changing alternating current to direct current

The xray tube operates on ______ current and the rest of the xray machine operates on ________ current

Direct; alternating

In conventional imaging, which of the following generators would technically produce the lowest contrast of the same technique was used on each one?

CPG

Tube current is the flow of ____ from the ____ to the _____ in the xray tube

Electrons; cathode; anode

How many electrical currents flow through the xray tube at the same time in three phase equipment?

3

Which of the following xray generators would be the most efficient at xray production?

HFG

Which of the following xray generators would have the lowest HVL?

Single phase

If a physicist is measuring kVp accuracy and a setting of 54 kVp yields a kVp reading of 60, is the kVp setting accurate?

No

True or false:

As less filtration is employed, the fewer low energy photons there are

False

True or false:

As filtration is increased, the quality of the beam increases

True

True or false:

if an xray unit has a total filtration of 2.5 mm Al. Eq and 1.0 mm Al. Is removed from the filtration, there will be more low energy photons in the remnant beam which will increase radiographic density

False

True or false:

As filtration increases, sharpness of detail increases

False

True or false:

If HVL is more than what it should be, protective filtration might need to be increased

False

True or false:

As beam quantity increases, HVL increases

False

True or false:

When using a compensating filter, you would increase your technique of the original technique was to demonstrate the less radiopaque anatomy

True

True or false:

An increase in filtration equals an increase in HVL

True

True or false:

An increase in kVp will increase the minimum and average energies of the beam

False

True or false:

An increase in filtration will increase the minimum and peak energies of the beam

False

True or false:

Using the same technique, a three phase machine will produce a beam with a higher average energy than a single phase machine

True

True or false:

Using the same technique, an increase in generator power and an increase in filtration will all increase the quantity of photons in the primary beam

False

True or false:

An increase in kVp will increase the quantity of xray photons produced in the anode

True

True or false:

An increase in kVp will increase the quantity of X-rays striking the IR

True

True or false:

HFGs produce more image sharpness than single phase generators

False

True or false:

HVL is the most accurate way to measure beam penetration

True

True or false:

Light is more energetic than X-rays

False

True or false:

As kVp increases, xray photon velocity increases

False

True or false:

As kVp increases, tube current velocity increases

True

When a projectile electron from the tube current interacts with an anode atoms electrons but does not impart enough energy to ionize the atom, the electrons are raised to a higher energy level. This is called ________. As the electrons settle back down to their original kinetic energy, they release _______.

Excitation; heat

When a projectile electron from the tube current bypasses an anode atoms electrons and comes under the influence of the nucleus, what type of X-ray is produced?

Bremsstrahlung radiation

When a projectile electron from the tube current interacts with an anode atom violently enough to ionize it, it will pull in an electron from an outer shell to return itself to a stable ground state. What type of xray is produced when this happens?

Characteristic radiation

What is the only purpose of filtration?

Lower patient dose

The filtration present in the xray tube after manufacturing, before the Al. slabs are placed in the beam is called ______ filtration

Inherent

An irregularly shaped filter used to balance densities in a radiograph when xraying anatomy with differing absorption characteristics is called a _______ filter

Compensating

The thickness of absorber needed to reduce beam intensity to ½ of its original value is termed the ______ ______ ______

Half value layer

Half value layer is a function of beam ______ and not a function of beam ______

Quality; quantity

If a service rep or physicist comes and determines that the kVp is found to be accurate, but the overall penetration (HVL) is too low, what needs to be done and why?

Increase filtration to increase HVL

If total filtration is over 3.0 mm Al. Eq, exposure is _______ and contrast is ______

Decreased; decreased

Xray machines operating above 70 kVp require how much filtration?

2.5 mm aluminum equivalent

List three types of inherent filtration

1. Glass window

2. Insulating oil

3. Glass tube

Alternating electrical current flows in ____ directions

Two

Direct electrical current flows in _______ direction

One

If you would use 32 mAs on a single phase machine, what new mAs would maintain IR exposure (image density) with a three phase machine or HFG?

16 mAs

If you use 100 kVp at 3.2 mAs on a PA CXR in a diagnostic exam room and you later have to do a portable AP CXR on the same patient, what new technique would you use for the portable image in order to maintain image density/ IR exposure?

90 kVp at 3.2 mAs

Give two ways to eliminate quantum mottle from an image

1. Increase kVp

2. Increase mAs

Give two ways to make the xray beam harder

1. Increase filtration

2. Increase kVp

What is the single most important quality of the xray beam?

Penetrability

The _____ setting determines the maximum or peak energy that any xray photon in the beam can possess

kVp

The xray beam is _______ which _______ subject contrast

Heterogenic; increases

Match the following electrical sine wave patterns with their proper generator and electrical current

CPG

Match the following electrical sine wave patterns with their proper generator and electrical current

Single phase (A/C)

Match the following electrical sine wave patterns with their proper generator and electrical current

Triple phase (D/C)

Match the following electrical sine wave patterns with their proper generator and electrical current

HFG

In the following beam spectrum graphs, the original beam is the solid line and the new beam is the dotted line. List the change made between the two beams

Increase in generator power

In the following beam spectrum graphs, the original beam is the solid line and the new beam is the dotted line. List the change made between the two beams:

Increase in mAs

In the following beam spectrum graphs, the original beam is the solid line and the new beam is the dotted line. List the change made between the two beams:

Increase in kVp

In the following beam spectrum graphs, the original beam is the solid line and the new beam is the dotted line. List the change made between the two beams:

Increase in filtration

Identify A-G on the following beam spectrum graph:

If you do need to increase your technique when using a compensating filter, how much would you increase it by?

8-10 kVp

Which xray beam is unfiltered?

B

Use the following table table to answer this question:

Yes

Approximately what is the half value layer thickness for this beam?

4 mm

Pertaining to the diagram above, each of the lines 1-4 represents the intensity change due to filtration at different kVp levels. According to the graph, the lowest kVp is represented by which curve?

4

Pertaining to the graph, the least amount of attenuation is seen for values represented by which curve?

1