X-ray Detection and Dental CT

What components do we have control over an x-ray source?

1. Photon energy (kVp)

2. # of photons produced (mA)

3. Exposure time (sec)

What components are x-ray interacions in the body?

1. Photo-electic

2. Compton Scatter

Why do we use Photo-eelctic and compton scatter?

We take advantage of these photon/tissue interactions to create a usable image

What is transmission imaging?

Photons transmitting through a patient

Because there is an anatomical overlay lacking some spatial information, what are some solutions?

Different views

Different modality

What is the Standard X-ray Design

Attenuation

Measure of scatter or absorbtion or what is happening in the body

Attenuation describes any other outcome

1. Absorption -photoelectic effect

2. Scattering- Classical/coherent/rayleigh or compton

How do you estimating attenuation

1. Driven by probability

2. Described by the linear attenuation

How would you interpret this?

How do we measure radiation dose?

Air molecules

If we shoot x-ray photos in air what happens?

Ionization via compton

What is a liberated charge called

Exposure

Why do we measure exposure?

To approximate dose

What is exposure

Charge collected per mass air

What is absorbed dose?

Energy deposited per mass of material

What is KERMA?

kinetic energy released in matter