anode heel efect

What is the anode heel effect?

A variation in X-ray beam intensity across the X-ray field.

Does the anode heel effect have anything to do with shoes?

No.

What causes the anode heel effect?

The angled anode absorbs some X-ray photons.

What is the usual anode angle in general radiography?

6°–20°.

Why is the anode angled?

To increase heat absorption and improve spatial resolution.

How does the anode angle increase heat capacity?

It increases the focal spot surface area.

How does the anode angle improve spatial resolution?

It decreases the effective focal spot size.

Which side of the X-ray beam has lower intensity?

The anode side.

Which side of the X-ray beam has higher intensity?

The cathode side.

Why are there fewer photons on the anode side?

Some photons are absorbed by the anode itself.

Where are X-ray photons produced within the anode?

Throughout the anode, not just at the surface.

What happens to photons created deep within the anode?

Some are absorbed before leaving the anode.

What is another way to describe the anode heel effect?

Decreased beam intensity on the anode side.

Is the anode heel effect always a disadvantage?

No.

How can radiographers use the heel effect to their advantage?

Place thicker anatomy under the cathode side.

Which side of the beam should be placed over thicker anatomy?

Cathode side.

Which side of the beam should be placed over thinner anatomy?

Anode side.

Why is the cathode side used over thicker anatomy?

It has greater beam intensity.

Why is the anode side used over thinner anatomy?

It has lower beam intensity.

In an abdomen radiograph, which side should be over the pelvis?

Cathode side.

Why is the pelvis placed under the cathode side?

The pelvis is denser and needs more photons.

Which side should be over the upper abdomen?

Anode side.

Why is the upper abdomen placed under the anode side?

It is less dense.

What happens when the anode angle decreases?

Heel effect increases.

What is the relationship between anode angle and heel effect?

Inverse.

As anode angle decreases, what happens to heel effect?

It increases.

As anode angle increases, what happens to heel effect?

It decreases.

Why does a smaller anode angle increase the heel effect?

More photons are absorbed within the anode.

What happens when the SID decreases?

Heel effect increases.

What is the relationship between SID and heel effect?

Inverse.

As SID decreases, what happens to heel effect?

It increases.

As SID increases, what happens to heel effect?

It decreases.

Why does a shorter SID increase the heel effect?

More of the intensity difference reaches the receptor.

What happens when field size increases?

Heel effect increases.

What is the relationship between field size and heel effect?

Direct.

As field size increases, what happens to heel effect?

It increases.

As field size decreases, what happens to heel effect?

It decreases.

Why does a larger field size increase the heel effect?

More of the high- and low-intensity beam is included.

Which side of the beam is stronger?

Cathode side.

Which side of the beam is weaker?

Anode side.

What side has more X-ray photons?

Cathode side.

What side has fewer X-ray photons?

Anode side.

What are the three factors that increase heel effect?

Decreased anode angle, decreased SID, increased field size.

Which factor increases heel effect: larger or smaller anode angle?

Smaller anode angle.

Which factor increases heel effect: longer or shorter SID?

Shorter SID.

Which factor increases heel effect: larger or smaller field size?

Larger field size.

What happens to beam intensity from cathode to anode?

It decreases.

Is beam intensity uniform across the X-ray field?

No.

What is the main clinical use of the heel effect?

To compensate for differences in patient thickness.

What ARRT phrase summarizes proper heel effect use?

Thick part under Cathode, Thin part under Anode.