X-Ray Interactions Flashcards
When x-ray passes through matter, it undergoes a process called: ______: the ____ in the number of x-ray ____ in the ____ as it passes through ____
Loss of ____ in the ____ as it travels through the ___.
- ____ body part will ____ more ____ than a ___ body part.
When x-ray passes through matter, it undergoes a process called: ATTENUATION: the REDUCTION in the number of x-ray PHOTONS in the BEAM as it passes through MATTER
Loss of ENERGY in the BEAM as it travels through the BODY.
- THICKER body part will ATTENUATE more ENERGY than a THINNER body part.
Attenuation
_____ in the number of x-ray ____ in the ____
Attenuation
REDUCTION in the number of x-ray PHOTONS in the BEAM
Attenuation
___% of the x-ray ___are _____ for each __ of ____ traveled.
Ex) at surface = 350 mR
1CM = 175 mR
2CM = 87.5 mR
3CM = 43.75 mR
Attenuation
50% of the x-ray PHOTONS are ATTENUATED for each CM of THICKNESS traveled.
Ex) at surface = 350 mR
1CM = 175 mR
2CM = 87.5 mR
3CM = 43.75 mR
Remnant Radiation
Remnant radiation is radiation that __________ and interacts with the ______.
Remnant Radiation
Remnant radiation is radiation that LEAVES THE PATIENT’S BODY and interacts with the IMAGE RECEPTOR (IR).
Interaction Basics
x-rays can:
- be transmitted ______ OR
interact with:
- ____
- ____
- ____
Interaction Basics
x-rays can:
- be transmitted WITHOUT INTERACTION OR
interact with:
- NUCLEUS OF AN ATOM
- ENTIRE ATOM
- ORBITAL ELECTRON
Photon Energy Dependent Interactions
- Low energy photons interact with ____
- Moderate energy photons interact with ____
- High energy photons interact with _____
Photon Energy Dependent Interactions
- Low energy photons interact with WHOLE ATOM
- Moderate energy photons interact with ORBITAL ELECTRONS
- High energy photons interact with NUCLEUS
Atomic Structure
- Nucleus
- ____ electrons
- electrons close to the nucleus are “____” (closer you get to the nucleus it protects itself)
- electrons further away are “____” or “____” (easier to knock out)
Atomic Structure
- Nucleus
- ORBITAL electrons
- electrons close to the nucleus are “BOUND” (closer you get to the nucleus it protects itself)
- electrons further away are “LOOSE” or “FREE” (easier to knock out)
What are the 5 basic interactions between x-rays and matter?
What are the 5 basic interactions between x-rays and matter?
- Coherent Scattering
- Photoelectric (PE) Absorption
- Compton Scattering
- Pair Production
- Photodisintegration
What are the photon energy ranges?
What are the photon energy ranges?
LOW, MODERATE, HIGH
Match the 5 basic interactions between x-rays and matters to the photon energy range
Coherent Scattering ———– Low photon energy range
Phoelectric (PE) Absorption and Compton Scattering ———– Moderate photon energy range
Pair Production and Photodisintegration ———- High photon energy range
Coherent Scatter
- _____ photons (___ beam) interacts with ______ or _____
- No electrons are ______
- Photon’s energy is given up by the ____ as a ____ of the same ____ in an ____ direction
Coherent Scatter
- INCIDENT photons (PRIMARY beam) interacts with ENTIRE ATOMS or OUTER ELECTRONS
- No electrons are EJECTED FROM THE SHELLS
- Photon’s energy is given up by the ATOM as a PHOTON of the same ENERGY in an ALTERED direction
Coherent Scatter
____ stabilizes itself by ___ a photon equal in energy to ________, but in a ________
Coherent Scatter
ATOM stabilizes itself by RELEASING a photon equal in energy to INCIDENT PHOTON (Ei), but in a DIFFERENT DIRECTION
__________ is usually not a factor in diagnostic x-ray due to:
- occurs only when ______ is lower than ___ kEv
- _____ will ____ out this ____ energy ___ before reaching the patient
- Coherent scatter _______ to forming the ________
COHERENT SCATTER is usually not a factor in diagnostic x-ray due to:
- occurs only when INCIDENT PHOTON ENERGY is lower than 10 kEv
- FILTRATION will FILTER out this LOW energy PHOTON before reaching the patient
- Coherent scatter DOES NOT CONTRIBUTE to forming the RADIOGRAPHIC IMAGE
Photoelectric Absorption (doesn’t create scatter - absorbs)
- ______ in primary beam interacts with _______
- ____ is ejected from it’s _____ and is termed a _____
- ________ is absorbed by the _____ (that’s what causes _____)
Photoelectric Absorption (doesn’t create scatter - absorbs)
- INCIDENT PHOTON in primary beam interacts with INNER SHELL ELECTRON
- ELECTRON is ejected from it’s ORBIT and is termed a PHOTOELECTRON
- INCIDENT PHOTON ENERGY is absorbed by the ATOM (that’s what causes BIOLOGICAL EFFECTS)
Photoelectric Absorption
- To stabilize ____, _____electron move to ____ the _____
- _________ cascade
Photoelectric Absorption
- To stabilize ATOM, OUTER SHELL electron move to FILL IN the VOID
- CHARACTERISTIC cascade
Photoelectric Absorption Happens When:
- Low ___ atoms experience photoelectric absorption interaction with _____
- Higher ___ atoms experience photoelectric absorption interaction in ___________
Ex) bone vs soft tissue
Photoelectric Absorption Happens When:
- Low Z# (ATOMIC NUMBER) atoms experience photoelectric absorption interaction with K-SHELL
- Higher Z# (ATOMIC NUMBER) atoms experience photoelectric absorption interaction in K, L, OR M SHELL
Ex) bone vs soft tissue
Compton Scatter (when x-ray very gray)
- ________ interacts with outer-shell, ____-bound ______ (in patient’s body) and ____ it (termed _______ or _____)
- _______ is ______ from its ____ path and continues with _______
Compton Scatter (when x-ray very gray)
- INCIDENT PHOTON (Ei) interacts with outer-shell, LOOSELY-bound ELECTRON (in patient’s body) and EJECTS it (termed COMPTON ELECTRON or RECOIL ELECTRON)
- INCIDENT PHOTON is DEFLECTED from its ORIGINAL path and continues with DECREASED ENERGY
Compton Scatter (when x-ray very gray)
- ________ travels until it fills a _____ in another _____ (can help stabilize another atom)
- ________ continue to ____ until ____ by the ______ effect
Compton Scatter (when x-ray very gray)
- RECOIL ELECTRON travels until it fills a VACANCY in another ATOM (can help stabilize another atom)
- SCATTERED PHOTON continue to INTERACT until ABSORBED by the PHOTOELECTRICAL effect
Compton Scatter (when x-ray very gray)
- Source of ________ and radiation ____ (gray film)
- Most _____ travels in _____ direction
- ______ - ____ electron may direct _____ (comes right back at you from patient body)
Compton Scatter (when x-ray very gray)
- Source of OCCUPATIONAL EXPOSURE and radiation FOG (gray film)
- Most SCATTER travels in FORWARD direction
- BACKSCATTER - RECOIL electron may direct BACKWARDS (comes right back at you from patient body)
Pair Production - doesn’t usually happen in diagnostic
- __________ must be ___ MeV or ____ (diagnostic does kVP - doesn’t usually meet this requirement)
- ________ absorbed (collides and hits) by _____ (of atom - becomes unstable)
*
Pair Production - doesn’t usually happen in diagnostic
- INCIDENT PHOTON ENERGY must be 1.02 MeV or HIGHER (diagnostic does kVP - doesn’t usually meet this requirement)
- PHOTON ENERGY absorbed (collides and hits) by NUCLEUS (of atom - becomes unstable)
Pair Production
- the ____ becomes ____
- ____ releases a _____ and ____ to ____ itself
- this process is called _____
Pair Production
- the NUCLEUS becomes UNSTABLE
- NUCLEUS releases a POSITRON and NEGATRON to STABILIZE itself
- this process is called ANNALATION
Pair Production
- Does not occur in _______ of _____
- More significant in _______
- Not a significant interaction until ____________ are being used
Pair Production
- Does not occur in DIAGNOSTIC RANGE of ENERGY
- More significant in RADIATION THERAPY
- Not a significant interaction until ENERGIES OF 10 MeV are being used
Photodisintegration
- ______ energy photon (__ - ___ MeV or ___)
- absorption of _____ by ___
- excited ____ releases _____
Photodisintegration
- EXTREMELY HIGH energy photon (7 - 15 MeV or GREATER)
- absorption of PHOTON by NUCLEUS
- excited NUCLEUS releases ALPHA PARTICLES
What 2 of the 5 interactions have a significant impact on x-ray images?
What 2 of the 5 interactions have a significant impact on x-ray images?
- PHOTOELECTRIC ABSORPTION
- COMPTON SCATTERING
Effect on Technical Factor Selection
As kVp increases (primary beam wavelength gets shorter)
- the number of _____ transmitted without______ ______
- decrease probability of _______
- increase ______ interactions
vice versa is true
Effect on Technical Factor Selection
As kVp increases (primary beam wavelength gets shorter)
- the number of PHOTONS transmitted without INTERACTION INCREASES
- decrease probability of PHOTOELECTRIC ABSORPTION
- increase COMPTON interactions
vice versa is true
If holding a patient during an x-ray, you’ll get radiation from _______ and patient will get radiation from _______
If holding a patient during an x-ray, you’ll get radiation from COMPTON RADIATION and patient will get radiation from PHOTOELECTRIC EXPOSURE
Effect on Technical Factor Selection
- ______ typically predominates within ______x-ray energy range due to ________
Effect on Technical Factor Selection
- COMPTON SCATTER typically predominates within DIAGNOSTIC x-ray energy range due to HIGHER kVp RANGES
Effect on Technical Factor Selection
_________ interactions predominate in two circumstances:
- _________ ranges (__-__ kEv produced by ___-___ kVp techniques)
- In elements with ________ (bone, solid organs)
- introduction of ________ results in ___________ (where ever contrast is, it’s going to absorb the radiation)
Effect on Technical Factor Selection
PHOTOELECTRIC ABSORPTION interactions predominate in two circumstances:
- LOWER ENERGY ranges (25-45 kEv produced by 40-70 kVp techniques)
- In elements with HIGHER Z# (ATOMIC NUMBER) (bone, solid organs)
- introduction of CONTRAST AGENTS results in INCREASE PHOTOELECTRIC ABSORPTION (where ever contrast is, it’s going to absorb the radiation)
Effects of Technical Factor Selection
When photoelectric absorption predominates:
- resulting image with have _________ (more ___ to ___)
- low ___, high ___
Optimum kVp = selecting the kVp which will produce a ________ and save the patient from _______
Effects of Technical Factor Selection
When photoelectric absorption predominates:
- resulting image with have SHORT SCALE CONTRAST (more BLACK to WHITE)
- low kVp, high mAs
Optimum kVp = selecting the kVp which will produce a GOOD IMAGE QUALITY and save the patient from HIGH RADIATION DOSAGE
Effects on Technical Factor Selection
When Compton interactions predominates:
- resulting image will have _______ (more ___ tones)
- high ____, low ___
Effects on Technical Factor Selection
When Compton interactions predominates:
- resulting image will have LONG SCALE CONTRAST (more GRAY tones)
- high kVp, low mAs
Patient Radiation Dosage
As photoelectric absorption increases, so does _________ (long energy beam, longer wavelenghs)
Patient Radiation Dosage
As photoelectric absorption increases, so does PATIENT’S RADIATION DOSAGE (long energy beam, longer wavelenghs)
Radiographer’s Occupational Dosage
As ______ increases, so does the RT radiation exposure
Radiographer’s Occupational Dosage
As COMPTON increases, so does the RT radiation exposure
Classical Scattering
- ___ energy
- interacts with ____
- ____ significance to ___ imaging (because we filter radiation before it hits patient)
Classical Scattering
- LOW energy
- interacts with WHOLE ATOM
- LITTLE significance to DIAGNOSTIC imaging (because we filter radiation before it hits patient)
Name 8 qualities of photoelectric absorption (MACKPHIM)
- Moderage energy
- Atom becomes unstable
- Characteristic cascade
- Knock out with inter shell electrons
- Patient radiation dose is increased
- Happens at lower kVp levels and high Z#
- Increase differential absorption
- More black and white images
List 9 qualities of Compton scattering (BLMHIMDIE)
- Backscatter radiation (radiation fog)
- Less differential absorption
- Moderate energy
- Higher kVp ranges
- Interacts with outer shell electrons
- More gray tones on film
- Decrease radiation dosage to patient
- Increase RT radiation dosage (holding patients)
- Ejected electron is called a recoil electron
