1. Rad T 110
Introduction to Radiation Protection and Interaction of X-ray and Matter
Sherer Ch 1 and Ch 2

2. Biologic Effects All radiographic exposures cause biologic effects
Consequently, risk versus benefit of receiving an exposure needs to be established
This is not your job

3. ALARA As low as reasonably achievable
This is the underlying tenet of modern radiography.
The radiography equivalent of, first do no harm.’
Basically, use the lowest exposure possible that will produce a good film.

4. Patient Education
Patients need to understand their exams so that they can actively and accurately participate in them.
This is not the same as getting consent
Prep, changing clothes, pre-medicating
If patients are cooperating then you will have an easier encounter and fewer repeats.

5. BERT Background radiation equivalent time
A great way of expressing exposure in a sensible way to the patient.
Based on background exposure of 300 mRem annually.

6. Electromagnetic Radiation
There are numerous types of electromagnetic radiation, i.e. microwaves, visible light, radiowaves, etc. We will focus primarily on x-rays.
Due to their energy level, x-rays are a form of ionizing radiation. This is how they cause biologic effects.
Not all electromagnetic radiation causes ionization; some forms cause excitation.

7. Particulate Radiation
Nuclear decay can produce both electromagnetic (gamma rays) and particulate radiation.
As a rule, particulate radiation is much more dangerous than electromagnetic radiation.
Beta, electrons
Alpha
neutrons

8. Equivalent Dose
This is a means of equalizing the effects of different types of radiation so that total dose can be accurately expressed.

9. Biologic Damage Photons ionize atoms Cellular damage Organic damage
Genetic or somatic manifestations
Genetic – your progeny
Somatic – to you
Can be early, late, or syndromes
Organic damage

10. Sources of Radiation Natural
Terrestrial
Cosmic
Internal
Basically, these sources of radiation are unavoidable
They combine to form what is referred to as background radiation.
In the US background exposure is approximately 360 mRad annually.

11. From NCRP Report No. 160, “Ionizing Radiation Exposure of the Population of the United States” (2009)

12. From NCRP Report No. 160, “Ionizing Radiation Exposure of the Population of the United States” (2009)

13. Significance of X-ray Absorption
X-rays are electromagnetic energy
As such, they can deposit energy when they interact with tissue
This is called absorption and results in the ionization of an atom.
The amount of energy absorbed becomes the absorbed dose measured in Rads or Grays.

14. Primary Radiation
Radiation produced in the tube and traveling in the primary beam; generally between the patient and the tube.
The beam is polyenergetic( there are a multitude of energies represented in the beam NOT a single energy.)

15. Attenuation Occurs when the beam interacts with tissue
Can occur thru absorption (photoelectric effect) and scatter (compton effect).
Photons do three things in tissue
Absorb
Scatter
Pass thru
The primary beam after it interacts becomes the exit beam.

18. Probability of Interaction
Absorption (Photoelectric effect)
Depends on beam energy, tissue atomic number, thickness, density
Scatter (Compton effect)
Depends primarily on beam energy.
Pair production and photodisintegration do not occur in the diagnostic energy range