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82 Cards in this Set
- Front
- Back
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what is a quality assurance program |
program designed to control and maintain standard of quality |
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QC |
processes to check quality |
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QA |
review of QC |
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QI |
make changes based on findings |
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who decides the standard of care |
professional collective not an agency agencies look at professional collective to adopt standards |
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AAMP stands for... |
American association for medical physics |
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what does ACR stand for |
American college of radiologists |
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ncrp stands for... who controls it |
national council on radiation protection -voluntary contributions from members |
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ICRP stands for... what is it |
international commission for radiologic protection - global body provides recommendations on radiation protection
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what is the goal of the AAPM |
identify and implement improvements on patient safety |
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why do people adopt standards by nonprofit organizations |
because they want to be practice good radiotherapy legal ramifications when serving under accepted standards |
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name non profit organizations with no power |
American association for medical physicists American college of radiologists national council for radiation protection international commission for radiological protection |
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name non profit organizations with power |
Nuclear regulatory committee state health department joint commission
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what does calibration mean |
to check and adjust and comparing with standard -make corrections and adjust |
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who is involved with calibration |
physics |
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when should calibration take place |
acceptance testing commissioning routing monitoring/maintenance major repairs |
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what does pmi stand for |
preventative maintenance inspection |
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calibration -acceptance test define |
acceptance of new equipment - contract between purchaser and manufacturer hospital physicist and manufacturer engineers test the product |
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calibration -commissioning for clinical use- when does this happen |
after acceptance test after major repairs annual QA - takes 2-4 days |
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what do we use for commissioning... |
water phantom |
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what 4 steps do we take when commissioning |
detailed review analysis of beam characteristic beam data entered into tx planning computer for dose calculations intricate measure of all beam parameters (check collimator factors, wedges) |
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calibration -what is routine monitoring and examples |
ongoing checks to monitor beam accuracy -dose rate -validate tx planning data -safe machine operation |
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calibration -what are major repairs and examples |
spot checks -wave guide -light bulb -table -mlc
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daily qa on treatment machine - 6 and tolerances |
lasers - 2mm odi - 2mm xray output - 3% electron output - 3% door interlocks - functional visual and audio monitor - functional |
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what are the tolerances for linear accelerators separated into |
non-IMRT IMRT stereotactic body radiation therapy/stereotactic radiosurgery |
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example of stereotactic body radiation therapy |
hypolung |
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example of stereotactic radiosurgery |
gamma knife |
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what qa check is done monthly with mlcs |
qualitative test - aka picket fence |
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how often is MLC transmission checked |
annually |
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how often is the radiation field for mlc checked |
monthly |
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how often is leaf positioning of mlcs checked |
monthly |
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what calibration equipment is used to collect exposure |
ionization chamber |
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what calibration equipment is used to measure exposure collected by ionization chamber |
electrometer or condenser |
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what calibration equipment do you need to measure ionization |
both electrometer/condenser and ionization chamber |
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what is a thermometer and barometer calibration equipment effected by |
temperature and pressure |
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what do ionization chambers do |
collects charge (measure exposure) |
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definition of exposure - |
amount of ionizations produced in air by radiation
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definition of ion |
atom or molecule with net charge due to loss or gain or one or more electrons |
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unit of exposure |
roentgin |
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how does an ionization chamber work? |
x-ray beam moves across air producing ions voltage is added along two ion collection plates - electric field is produced, positive ions move towards - plate and negative ions move towards + plate. collection charge of either plate can be measured |
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problems with charge collection |
ionization must occur in a specific volume because ions are not controllable
some electrons deposit their energy inside the region and some outside the region |
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electronic equilibrium define |
when ionization lost = ionization gained when the energy loss = energy gain this is when the measurements are accurate |
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when are the measurements accurate |
when electronic equilibrium is achieved |
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purpose of ionization chamber |
used to collect exposure in order to measure exposure for calibration |
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two types of ionization chambers |
pseudo free air ionization chamber free air ionization chamber |
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which ionization chamber is standard |
free air ionization chamber |
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facts about free air ionization chamber |
true "air" chamber (wall of air) delicate and bulky found only in national laboratories calibrated along known radionuclides |
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pseudo free air ionization chamber fact |
walls made of air equivalent material
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pseudo free air ionization chamber also known as |
thimble chamber |
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how does the thimble chambers work |
air travels through spherical volume and is irradiated with photon beam
air is surrounded by air equivalent walls
the outer and inner sphere is kept at a distance of which electrons can travel, this creates electronic equilibrium
a free air chamber is created
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what are two types of thimble chambers |
farmer chamber condenser chamber |
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when are farmer chambers used |
megavoltage x and gamma radiation |
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when are condenser chambers used |
for less than or equal to 2 MeV |
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where are primary ionization chambers calibrated and how often |
they are calibrated at national laboratory, sent there once a year |
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where are primary ionization chambers calibrated |
calibrated to the primary but must be traced to the national laboratory |
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which chamber is used for megavoltage radiation |
thimble chamber |
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other ionization chambers in the department |
head of gantry RBA |
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how does temperature and pressure effect ionization chambers |
number of molecules in the atmosphere |
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at what temperature and pressure is density of air the highest |
when pressure is high and temperature is low |
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what happens to the ionization reading when temperature increases |
ionization reading decreases |
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what happens to the ionization reading when temperature decreases |
ionization reading increases |
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what happens to the ionization reading when pressure increases |
ionization reading increases |
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what happens to the ionization reading when pressure decreases |
ionization reading decreases |
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what are electrometers |
charge measuring devices attached to the ionization chambers |
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purpose of electrometers |
measures collected exposures |
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what do we use to measure lower energies |
condenser |
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megavoltage what do we use to measure higher energies |
electrometers |
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name an electrometer |
max 4000 |
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what is isoalign |
helps perform a multitude of alignment procedures |
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what does star shot do |
measures coincidence -collimator -gantry -table |
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star shot process |
open collimator to a slit less than 1mm shoot 50 MUs and rotate 20 degrees
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what is the purpose of radiation/light field coincidence? |
to verify light field matches radiation field |
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how to check radiation/light field coincidence |
place film on table, set field size, mark c/a and corners |
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how to check assymetric jaws/ match line/ beam split |
close inferior jaws, radiate close superior jaws, radiate |
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leaf positioning - picket fence calibration -film is exposed to...
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8 field sets that are 5x40cm every 5cm |
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motion tolerance for breathing and set up |
breathing 4mm set-up 6mm
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absolute dose tolerance |
+- 2% |
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relative dose tolerance |
+-2.2-4.5% |
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output, block, wedge dose tolerance |
+-0.5 - 2% |
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isodose plan tolerance |
+/- 3% |
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annual occupational dose limit for workers |
50 msv |
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annual dose limit for the public |
5msv |
