LIMITS EXPOSURE TO IONIZING RADIATION - SETS DOSE LIMITS PER YEAR 5 rem/YEAR
DEFINE ALARA
AS LOW AS REASONABLY ACHIEVABLE
WHAT IS THE DOSE RESPONSE CURVE
ASSUMES THERE IS A LINEAR, NONTHRESHOLD RELATIONSHIP BETWEEN DOSE AND BIOLOGICAL RESPONSE
DEFINE LINEAR NONTHRESHOLD
CHANCE OF DAMAGE IS PROPORTIONAL TO THE AMOUNT OF RADIATION ABSORBED
DIRECTLY PROPORTIONAL
WHAT ARE THE 3 PARTS OF THE CARDINAL RULE OF RADIOGRAPHY
TIME, DISTANCE, SHIELDING
WHAT IS THE LEAD EQUIVALENCE FOR
PRIMARY BEAM SHIELDS
SECONDARY BEAM SHIELDS
PRIMARY .5 mm LEAD
SECONDARY .25 mm LEAD
NAME TWO TYPES OF FILM BADGES
WHAT TYPE DO RTs USE
FILM BADGE - TWO PIECES OF FILM INSIDE HOLDER
THERMOLUMINECENCE DOSIMETER (RTs)
WHAT IS THE TDL READ IN
mR = MILLIRENKIN
DEFINE BERT
BACKGROUND EQUIVALENT RADIATION TIME
DEFINE PERCEIVED RISK
ASKS INDIVIDUAL OR GROUP TO EXPRESS PERCEPTION OF RISK - AWARENESS TOOL
DEFINE RISK COMPARISON
COMPARES TWO OR MORE ACTIVITIES
WHAT IS BERT USED FOR
COMPARES SPECIFIC RAD STUDY TO EQUIVALENT IN NATURAL BACKGROUND RADIATION EXPOSURE WHEN RISK IS SMALL AND BENEFIT IS GREAT (PT SHOULD HAVE EXAM)
DEFINE GSD
GENETIC SIGNIFICANT DOSE
INCREASE IN DIAGNOSTIC EXPOSURES; AGING POPULATION, INCREASED LIFE SPAN, DEFENSIVE MEDICINE
DEFINE LATENT PERIOD
UNSEEN TIME PERIOD
ETHICS ARE WHAT
RULES OF BEHAVIOR
GENERAL GUIDELINE
LAWS ARE BASED ON ETHICS
LAWS ARE BASED ON WHAT
ETHICS
NEGLIGENCE REQUIRES WHAT
PROVE DUTY EXISITS
BREACH OF DUTY
CAUSE IS DUE TO PROFESSIONAL ACTIONS
INJURY MUST BE PROVED
ELECTROMAGNETIC RADIATION
NO MASS / CHARGE ; PURE ENERGY
BEHAVES AS WAVES AND PARTICLES
HOW DOES EMR REFLECT WAVES AND PARTICLES
WHEN TRAVEL IN SPACE BEHAVE AS SINE WAVE
WHEN INTERACTING WITH MATTER BEHAVE AS PARTICLE
PARTICULATE
ALPHA AND BETA ; HIGH SPEED e- (HAS 2 P AND 2 N)
HIGHLY PENETRATING
HETEROGENOUS - MANY WAVELENGTHS
POLYENERGETIC - MANY ENERGIES
TRAVEL IN STAIGHT LINE
CAN NOT BE FOCUSED
ELECTRICALLY NEUTRAL
PRODUCE SECONDARY AND SCATTER RADIATION
TWO TYPES OF REACTIONS MOST PREVALENT
PHOTOELECTRIC ABSORPTION
COMPTON SCATTER - MOST PREVALENT IN BODY
LIST PROPERTIES OF XRAYS
FLUORESCE
CUASE BIOLOGIC CHANGE
IONIZE MATTER
AFFECT PHOTOGRAPHIC FILM
TRAVEL AT SPEED OF LIGHT (VACUUM)
RELEASE SMALL AMOUNT OF HEAT WHEN PASS THRU MATTER
WHAT DOES THE TUBE CONSIST OF
GLASS ENVELOPE (VACUUM)
CATHODE (-) CHARGE - SOURDE OF e-
LARGE AND SMALL FILAMENT - DUAL FOCUS
FOCUSING CUP (-) CHARGED AND FOCUSES e- STREAM
ANODE (+) CHARGE - TARGET, STEM, ROTOR-STATOR
WHAT ARE THE FUNCTIONS OF THE TUBE
FILAMENT IS HEATED (mA)
BOILS OFF e- (THERMIONIC EMISSION)
mA IS DIRECTLY PROPORTIONAL TO # OF e- FLOWING FROM CATHODE TO ANODE
AS mA INCREASES GET BIGGER CLOUD
2200 DEGREES CELSIUS
TIME CONTROLS AMOUNT OF TIME e- ARE FLOWING
IF mA DOUBLES, S DOUBLES OR mAs DOUBLES, THE BEAM INTENSTIY DOUBLES
DIRECTLY PROPORTIONAL
WHAT DOES mA MEASURE
TUBE CURRENT
WHAT % OF THE PRIMARY BEAM IS HEAT AND WHAT % IS ACTUAL XRAY
99% HEAT
1% X-RAY
WHEN DO WE SEE BREMSSTRAHLUNG
< 70 kVp
WHEN DO WE SEE CHARACTERISTIC
>70 kVp OCCURS WHEN e- STRIKE INNER SHELL
WHERE IS PRIMARY RADIATION PRODUCED
AT THE TARGET OF THE ANODE - FOCAL SPOT
WHICH PART OF THE BEAM IS THE PRIMARY OR USEFUL PART
RADIATION THAT EXITS AT THE PORT
WHAT IS CONSIDERED LEAKAGE RADIATION
ANY RADIATION THAT EXITS PROTECTIVE HOUSEING OTHER THAN AT PORT
WHAT IS REMNANT RADIATION
EXIT OR IMAGE FORMING RADIATION - PORTION OF PRIMARY BEAM THAT PASSES THRU PT WITHOUT INTERACTION
WHAT IS SCATTER RADIATION
RADIATION THAT HAS INTERACTED WITH MATTER AND CHANGES DIRECTION OF TRAVEL
WHAT IS SECONDARY RADIATION
RADIATION PRODUCED IN THE PTS BODY
IF YOU INCREASE kVp WHAT HAPPENS TO COMPTON SCATTER
IT INCREASES ALSO
GENERATORS
60 Hz AC CURRENT (PROVIDES 1+ AND 1- PULSE PER CYCLE)
CONVERTED TO PULSATING CURRENT THRU RECTIFICATION
WHAT IS RECTIFICATION
REROUTING OF (-) PULSES TO (+) PULESE
PRODUCES PULSATING DC
WHAT ARE THE THREE TYPES OF RECTIFICATION
SINGLE PHASE - REROUTS CURRENT SO 2 (+) PULSES/CYCLE PRODUCED;VERY INEFFICIENT;VOLTAGE DROPS TO "0" 120X/SEC; ROOT MEAN SQUARE - AVG ENERGY 70.7% OF kVp
3 PHASE - COMBINES 3 VOLTAGE WAVEFORMS SO AS 1 STARTS TO DROP TO 0 THE NEXT BOOSTS THE VOLTAGE BACK UP- VOLTAGE NEVER DROPS TO "0". WHEN RECTIFICATION IS APPLIED IT PRODUCES 6 OR 12 PULSES/CYCLE;ROOT MEAN SQUARE 3 PHASE 6 PULSE=92% ; ROOT MEAN SQUARE 3 PHASE 12 PULSE= 97%
HIGH FREQUENCY POWER CONVERTERS CHANGE 60 Hz TO 6000Hz; PRODUCES MINIMAL VOLTAGE RIPPLE;ROOT MEAN SQUARE 97-98%
FALLING LOAD MEANS
STARTS EXPOSURE AT MAXIMUM mA; USES MAX mA UNTIL HEAT LOAD IS REACHED THEN DROPS IT TO NEXT LOWER LEVEL- PROCESS CONTINUES TILL APPROPRIATE mA IS MET
REDUCES EXPOSURE TIME
TAKES ADVANTAGE OF TUBE LOADING CAPABILITIES
CAPACITOR DISCHARGE
BATTERY POWERED
CAPACITOR DISCHARGE - STORES e- CHARGE
BATTERY POWERED - NICKEL CADNIUM - CONSISTENT mA AND kVp
FLUOROSCOPIC
LOWER SETTINGS mA .5-5 mA LONGER PERIOD OF TIME
LIMITATIONS - VIEWING MONITOR
IMAGE INTENSIFICATION
AMPLIFIES IMAGE BRIGHTNESS
TOTAL BRIGHTNESS GAIN = FLUX GAIN X MINIFICATION GAIN
FLUX GAIN DETERMINED BY CONVERSION EFFICIENCY OF THE OUTPUT PHOSPHOR
MINI GAIN e- EMITTED BY PHOTOCATHODE ARE COMPRESSED TO SIZE OF SMALLER OUTPUT PHOSPHOR
INPUT PHOSPHOR EMITS LIGHT IN RESPONSE TO XRAY PHOTONS
PHOTOCATHODE ABSORBS LIGHT AND EMITS e- (PHOTOEMISSION)
ELECTROSTATIC LENSES FOCUS, ACCELERATE AND INVERT THE e-
ACCELERATING ANODE ALSO ATTRACTS THE e-
e- STRIKES OUTPUT PHOSPHOR (ZINC CADMIUN SULFIDE)
OUTPUT PHOSPHOR EMITS VISIBLE LIGHT
WHAT 3 THINGS HAPPEN TO PRIMARY BEAM
SCATTER
ABSORPTION
TRANSMISSION (PASS THRU W/O INTERACTING)
PRIMARY BEAN ATTENUATION = ?
REMNANT RADIATION
GAMMA RADIATION
ORIGNINATES WITHIN THE NUCLEUS
MONOENERGETIC
ATTENUATION IS EXPONENTIAL (BEAM IS REDUCED BY A CERTAIN % FOR EA INCREMENT OR THICKNESS)
HVL IS CONSISTENT
X-RADIATION
POLYENERGETIC - MANY ENERGIES
BEAM IS ATTENUATED AT DIFFERENT RATES PER GIVEN THICKNES
HVL INCREASES AS FILTRATION OR TISSUE THICKNESS INCREASES
GENERAL CONCEPTS
BINDING ENERGIES ARE HIGHER FOR GREATER ATOMIC # ELEMENTS
INNER ORBITAL SHELLS (HIGHER BINDING ENERGIES/LOWER TOTAL ENERGIES)
OUTER ORBITAL SHELLS (LOWER BINDING ENERGIES/HIGHER TOTAL ENERGIES)
WHAT ARE FOUR (4) FACTORS THAT AFFECT ATTENUATION
1. INCREASED PHOTON ENERGY (INCREASE TRANSMISSION, DECREASE ATTENUATION)
2. ATOMIC DENSITY
3. ATOMIC # OR Z#
4. ELECTRONS PER GRAM
AN INCREASE IN ANY OF THESE FACTORS RESULTS IN A DECREASE IN TRANSMISSION AND INCREASE IN ATTENUATION
PHOTOELECTRIC EFFECT
AKA - ABSORPTION
INCIDENT PHOTON INTERACTS W/ AND EJECTS A TIGHTLY BOUND INNER SHELL e- AND IS COMPLETELY ABSORBED (CASCADE EFFECT)
SECONDARY RADIATION MORE LIKELY TO OCCUR WHEN X-RAY PHOTON ENERGY AND INNER SHELL BINDING ENERGY ARE CLOSE TOGETHER
PHOTOELECTRIC EFFECT IS MEASURED HOW
IN KeV
HIGH ATOMIC # ELEMENTS AND INNERMOST SHELLS
IN DIAGNOSTICS WHICH AFFECT IS PREDOMINANT
COMPTON SCATTER
PAIR PRODUCTION
OPPOSITES
COMPTON SCATTERING
INCIDENT PHOTON INTERACTS W/ AND EJECTS A LOOSLEY BOUND OUTER SHELL e-
SCATTERED PHOTON CONTINUES IN DIFFERENT DIRETCTION W/ SHORTER WAVELENGHT AND LESS ENERGY THAN INCIDENT PHOTON.
BACKSCATTER, SCATTERED BACK TO SOURCE
**PRIMARY SOURCE OF OCCUPATIONAL EXPOSURE
COMPTON SCATTERING
RECOIL e- OR COMPTON e-
COMPTON SCATTER PHOTON
LOWER ENERGY
LOWER WAVELENGTH
LOWER FREQUENCEY
WHAT IS THE PRIMARY SOURCE OF OCCUPATIONAL EXPOSURE
COMPTON SCATTER
COHERENT SCATTERING
AKA - CLASSICAL, RAYLEIGH OR THOMPSON
INCIDENT PHOTON INTERACTS W/ ATOM AS A WHOLE
EXCITATION OF ATOMS, EXCESS ENERGY IS GIVEN OFF AS A COHERENT SCATTERED PHOTON
(HAS SAME ENERGY, FREQUENCY AND WAVELENGTH AS INCIDENT PHOTON)
PAIR PRODUCTION
INCIDENT PHOTON INTERACTS W/ THE NUCLEAR FIELD AND LOSES ALL ITS ENERGY
ENERGY IS CONVERTED TO A POSITRON AND NEGATRON.
POSITRONS QUICKLY INTERACTS W/ AN e- AND CONVERTS BACK TO ENERGY
(IN THE FORM OF TWO GAMMA PHOTONS MOVING IN OPPOSITE DIRECTIONS)
AKA - ANNIHILATION REACTION
PHOTODISINTIGRATION
ABSORBED
INCIDENT PHOTON INTERACTS W/ THE NUCLEUS
NUCLEUS RESPONDS BY EMITTING A NUCLEAR FRAGMENT
INTERACTIONS OF PARTICULATE RADIATION W/ MATTER
ALPHA & BETA RADIATION LOSE ENERGY BY PRODUCING IONS
PARTICLES PASS NEAR A NEUTRAL ATOM & THRU ELECTROSTATIC FORCE, REMOVES e- THRU ATTRATION/REPULSION
ELECTROSTATIC INTERACTIONS NO CHANGE IN TOTAL KINETIC ENERGY OF INTERACTION PARTICLES-KINETIC ENERGY OF A BETA PARTICLE IS TRANSFERED TO ORBITAL e-
NON-ELECTROSTATIC INTERACTION TOTAL KINETIC ENRGY OF PARTICL IS CHANGED BECAUSE SOME OF THE ENERGY IS TRANSFORMED INTO ANOTHER TYPE OF ENERGY (BREMS)
LINEAR ENERGY TRANSFER AND SPECIFIC IONIZATION
LET - RATE ENERGY IS DEPOSITED IN MATTER
ION PAIRS PRODUCED PER UNIT OF TRAVEL
SI - RATE ENERGY IS LOST BY RADIATION
BOTH ARE DIRECTLY RELATED
X-RAY AND GAMMA RAYS - HAVE LOW LET AND SI
ALPHA AND BETA HAVE HIGH LET AND SI (MORE DAMAGING)
WHAT IS SKIN DOSE
ACTUAL MEASURE OF RADIATION RECEIVED BY A GIVEN AREA OF SKIN
WHAT IS ESE
ENTRANCE SKIN EXPOSURE - ESTIMATED VALUE USED BY GOVERNMENTAL AGENCIES TO REGULATE DIAGNOSTIC X-RAY EXPOSURES
DEPTH DOSE
% OF SKIN DOSE FOUND AT A CERTAIN DEPTH IN THE PATIENT
ORGAN DOSE
DOSE RECIEVED BY A PARTICULAR ORGAN
INTEGRAL DOSE
AMOUNT OF ENERGY ABSORBED BY A SPECIFIC TISSUE
WHAT ARE OTHER NAMES FOR INTEGRAL DOSE
MEAN MARROW DOSE
GONADOL DOSE
GLANDUALR DOSE
CUMMULATIVE DOSE
WHAT ARE POLYENERGETIC FOR A GIVEN ATOME
X-RADIATION AND BETA
THE HVL OF GAMMA RADIATION FROM A GIVEN ATOM IS THE SAME NO MATTER HOW MANY THICKNESS OF MATERIAL THE RADIATION HAS TO PASS THRU.
TRUE OR FALSE
TRUE
IF THE INITIAL ENERGY OF THE BEAM IS 51 KeV, THEN ___ ION PAIRS ARE PRODUCED WITH A PHOTOELECTRIC EFFECT
1500
THE RATE AT WHICH ENERGY IS DEPOSITED IN MATTER DESCRIBES WHAT
LINEAR ENERGY TRANSFER OR LET
AS Z# INCREASES, THE PROBABILITY OF COMPTON SCATTER (INCREASES/DECREASES)?
DECREASES
REMEMBER INVERSE RELATIONSHIP
AS ONE GOES UP THE OTHER GOES DOWN
KERMA
KENETIC ENERGY RELEASED IN MATTER
WHAT MEASURES PATIENT DOSE MOST OFTEN
SKIN DOSE
WHEN ELECTRONS STIVE TO FILL SHELLS AND GIVE OFF X-RAYS IN THE PROCESS IT IS KNOWN AS
CHARACTERISTIC CASCADE
WHAT CAUSES EXCITATION RATHER THAN INONIZATION?
COHERENT SCATTER
WHAT IS MOST LIKELY AN OUTER ORBIT INTERACTION?
COMPTON SCATTER
WHAT IS THE BASIS FOR USING LEAD APRONS
PHOTOELECTRIC EFFECT
WHY USE HIGH kVp W/ CONTRAST STUDIES
HIGH kVp PRODUCES BEAMS W/ ENERGIES CLOSE TO THE BINDING ENERGY OF THE INNERMOST SHELL OF BARIUM. THIS PROMOTES THE PRODUCTION OF PHOTOELECTRIC EFFECT AND MAXIMIZES CONTRAST
HOW DOES AN INCREASE IN ENERGY AFFECT COMPTON SCATTERING
INCREASES IN ENERGY INCREASES THE RELATIVE PROBABILTIY OF COMPTON SCATTER OVER PHOTOELECTRIC EFFECT. NUMERICALLY, SCATTER INTERACTIONS DECREASE AS PHOTON ENERGY INCREASE, BUT THERE IS AN APPEARANCE OF GREATER SCATTER ON AN XRAY FILM AS MORE SCATTER REACHES THE FILM
PHOTODISINTIGRATION
NUCLEAR FRAMENT IS FORMED
CLASSICAL, THOMPSON, COHERENT
UNDER 10 KeV
INTERACTS W/ TOTAL ATOM
ATOM ABOSRBS PHOTON, BECOMES EXCITED, GIVES OFF PHOTON W/ SAME WL AND ENERGY
SCATTER NOT IMPORTANT
COMPTON
THRU DIAGNOSTIC RANGE
INTERACTS W/ OUTER SHELL e-, e- IS EJECTED, CONTINUES W/ LESS ENERGY IN NEW DIRECTION, SIGNIFICANT AS MAJOR SOURCE OF FOG ON FILM, PT DOSE AND TECH DOSE INCREASE
SCATTER DIAGNOSTIC RADIOLOGY
PHOTOELECTRIC
THRU DIAGNOSTIC RANGE; MUST BE = TO OR > THAN BINDING ENERGY
INTERACTS W/ INNER SHELL e-, EJECTS e- RESULTS IN CASCADE EFFECT. SIGNIFICANT BCS BONE HAS MORE INTERACTIONS THAN SOFT TISSUE, RESULTING IN DIFFERENTIAL ABSORPTION
SECONDARY DIAGNOSTIC RADIOLOGY
PAIR PRODUCTION
1.02 MeV; NOT SIGNIFICANT BELOW 10 KeV
INTERACTS W/ NUCLEAR FIELD CONVERTS ENERGY INTOONE e- AND ONE POSITRON.
POSITRON QUICKLY INTERACTS W/ AVAILABLE e- W/ MUTUAL INHALATION RESULTING. GIVING OFF 1.02 MeV OF ENERGY IN MULTIPLE PHOTONS
PHOTODISINTEGRATION
OVER 10 MeV
PHOTON INTERACTS W/ NUCLEUS, NUCLEAR FIELD DISRUPTED BY PHOTON ENERGY AND NUCL IS DISASSEMBLED. NUCLEAR FRAGMENTS ARE CREATED AND MOVE AWAY
SECONDARY - RADIATION THERAPY
REMEMBER THIS
AS ENERGY (kVp) INCREASES, PHOTOELECTRIC EFFECT DECREASES GREATLY
AS ENERGY (kVp) INCREASES, THE % OF COMPTON INTERACTION DECREASES SLIGHTLY
THEREFORE, AS kVp GOES UP, FEWER SCATTER PHOTONS ARE CREATED. AS MORE SCATTER IS RECORED ON FILM, THEREFOR WE SEE MORE IMPACT FROM COMPTON INTERACTIONS AS kVp GOES UP
