Radiation Biology 2
Terms
undefined, object
copy deck
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Tranference of energy from an x-ray beam to the atoms of the body?
What is involved in it? -
Abosorption
Photoelectric efect - Unit of absorption expressed in rad or gray?
- absorbed dose
- primary radiation emerges from the tube target and consists of x-ray photons of ___________ energies.
- various
- The positively charged target in the x-ray tube.
- Anode
- The negatively charged source of the high speed electrons
- Cathode
- The glass envelope encasing the x-ray tube
- inherent filtration
- is any that decreases the intensity of the primary photon beam.
- Attenuation
- Higher kvp would would cause what two photon interactions to happen?
-
Exit or image formation
no interaction
small angle scatter - What types of photon interactions are there?
-
Exit or image formation
no interaction
small angle scatter (creates fog)
Attenuated
scattered photon (affects us and doctor)
absorbed (photoelectric effect causes this to happen) - Back scatter and side scatter affect what?
- occupational dose
- When is FDG injected?
- petscans
- How is recorded detail measured?
- line pairs per mm
- What factors affect recorded detail?
-
SID
OID
Screen
Focal Spot Size
motion - Visibility of detail
-
Grid
KVP and MAS
Collimation - As X-RAY energy increases
-
1. more compton
2. less pe interaction
3. more transmission
4. less differential absorption - As tissue atomic number increases
-
no change in compton
more pe
less transmission thru tissue - As tissue mass density increases
-
more compton
more pe
reduced transmission - What is the energy range for coherent scattering?
- 1-50
- Who discovered x-rays
- Wilhelm Conrad Roentgen Nov 8 1895
- who discovered radioactivity?
- Antoine Henri Becqurel 1898
- Who discovered isolated radium?
- Pierre and Marie Curie 1898
- Who was the first known radiation death?
- Clarence Dally 1904
- If an atom loses an orbital electron it forms what?
- an ion pair
- The amount of energy transferred to electrons by ionizing radiation is the basis of of the concept of?
- radiation dose
- For the different types of radiation there is a?
- quality factor
- What is the energy range for photoelectric absorption and what does it have to do with?
- 1-50, inner shell electron
- what is the energy range for compton scattering and what does it have to do with?
- 60-90, outer shell electron
- Energy range 1.02 mEv
- Pair production
- An X-Ray image results from the difference between the x-rays absorbed photoelctrically in the patient and those transmitted to the IR?
- Differential Absorption
- What causes differential absorption?
-
Compton Scattering
PE effect
X-rays transmitted - Maximum differential absorption requires what?
- Optimum KVP
- To image small differences in small tissue, what should you do?
- lower kvp
- How do you lower differential absorption?
- lower kvp
- What 2 things affect differential absorption?
-
atomic # in tissue
mass density in atoms - X-ray is composed of what 2 types of photons?
-
Characteristic
Bremstralong - Incidental electron interacts w/ an inner shell electron
- Characteristic photon
- deceleration of electrons by interaction w/ target atoms.
- Brems photon
- What is the purpose of added filtration?
- to reduce patients skin dose
- If radiation produces positive and negative particles its called?
- Ionizing radiation
- Where does terrestrial radiation come from?
- soil and rocks
- The average annual DE from manmade and natural resources?
- 360 mRem
- What is the first decay product of Radium?
- Radon
- Damage which leads to abnormal cell function is termed?
- Biologic Damage
- What radionuclides are responsible for internal radiation?
-
Potassium 40
Carbon-14
strontium-90 - Quantity that attempts to take into account the variation in biologic harm produced by different types of radiation?
- Equivalent dose
-
What damage would 25 rem cause?
150?
200-600?
250?
600? -
blood changes (fewer lymphocytes)
nausea, diarreah
Erythmea
Gonadal sterility
death