QA Flashcards
quality control procedures ensure that all is in proper working order according to what 3 procedures
manufacturer, department, and national specifications
list 2 devices used to verify machine output and consistency
geometric and anthropomorphic phantoms
how does each oncology center determine the frequency of quality control checks
the stability of equipment performance, and recommendations set by the AAPM
list the 4 daily tests that could seriously affect patient positioning
laser, ODI, procedures to verify accurate patient dose delivery, safety equipment
list at least 2 examples of mechanical and electrical devices that a radiation therapist should regularly check
override switches, emergency off switches, limit switches, collision rings, dead man switch
list 3 monthly QA tests
treatment couch indicators, field light/ radiation congruency, beam flatness
who establish and manages the quality control procedures and tolerances
physicist
list 3 examples of treatment room items that must be checked daily for the care, safety, and hygiene of patients
IV poles, markers, flashlight
are both audio and video equipment necessary for patient treatment, or is one or the other satisfactory
both audio and video are necessary for treatment
how often should audio and video equipment be documented
daily
who should be notified if audio and video equipment malfunctions? when?
the engineer or physicist immediately
how often should block cutting systems be checked?
monthly
how often should the block room be assessed?
annually
how is the block room assessed?
with an air sample analysis that follows OSHA guidelines
does a block room assessment need to be documented
yes, proper documentation should be kept in a log with all corrective actions noted
list the 4 uses of accessory devices
indicate beam direction, modify beam attenuation, aid in positioning, and immobilization
list 2 latching mechanisms for interlocking accessories that should be checked monthly
electron cones, wedges, trays, compensators
what are the 3 methods for checking accessory devices?
visualization, manipulation, and radiography
when checking accessory devices, what 6 items should the record of results include?
date of check, device evaluated, condition of device, person notified of defect, corrective action taken, follow up dates and information
what 5 items should a treatment chart include? give an example of each.
patient identification, initial physical evaluation of patient, treatment planning, treatment execution, QA checklists
with regard to a patient’s treatment chart, what 6 items should a radiation therapist record daily
date, time out performed, daily and cumulative doses to all prescription, critical structure, and anatomic reference points
when should a chart check be performed?
before treatment delivery, weekly, at treatment completion
what is R & V?
record and verify
what should you do if an unexpected value or message is displayed by the R & V system?
document and inform the facility engineer or physics for follow up
every day therapists must verify that the room lasers and ODI are within
2 mm
define action levels
tolerance levels set for a procedure that when fall outside the allowed deviation will bring about actions to return values back to compliance
treatment may continue, but the cause should be investigated (level 1/level 2/level 3 action level)
level 1
treatment may continue, but an intervention should be scheduled within 1 to 2 working days (level 1/level 2/ level 3 action level)
level 2
requires immediate action, treatments should be stopped during this time (level 1/level 2/ level 3 action level)
level 3
QA concerns for MLC’s fall into what 2 categories?
attenuation properties, positional precision
how often should qualitative tests be performed on linac that perform IMRT and VMAT
weekly
describe the picket fence test?
the picket fence test looks at deviations in interleaf transmission
describe monthly QA procedures for multi leaf collimation
should include verification of the MLC setting versus the radiation field
describe annual QC procedures for multi leaf collimation
annual procedures include checking that the average of leaf and interleaf leakage for all energies is +/- 0.5% from commissioning baseline
what is the definition of controlled area
a limited access area in which the occupational exposure of personnel to a radiation producing equipment or radioactive materials is supervised by an individual in charge of radiation protection
what is the maximum permissible dose equivalent for a controlled area
5 mSv/yr
what is the definition of noncontrolled / uncontrolled area
any other area in the environment, doses suitable for the general public would apply in these areas
what is the maximum permissible dose equivalent for a noncontrolled / uncontrolled area
1 mSv/yr
protection through the source housing is required against what 3 types of radiation
primary, scattered, leakage
what is the definition of primary barrier
a barrier sufficient to attenuate the useful beam to the required degree
what is the definition of secondary barrier
the required barrier against stray radiation (leakage and scatter)
what is the definition of workload?
for megavoltage matines, W is usually stated in terms of weekly dose delivered at 1 m from the source. this can be estimated by multiplying the number of patients treated per week with the dose delivered per patient at 1 m
how is workload expressed
in dose per week at 1 m
what is the definition of use factor
fraction of the operating time during which the radiation under consideration is directed toward a particular barrier
what is the definition of occupancy factor
fraction of the operating time during which the area of interest is occupied by the individual
what is the definition of distance with regard to factors that enter into the calculation of barrier thickness
distance in meters from the radiation source to the area to be protected
what is the occupancy factor for areas occupied full time by an individual
1
what is the occupancy factor for outdoor areas with only transient pedestrian or vehicular traffic, unattended parking lots, unattended vehicular drop-off areas, stairways, and unattended elevators
1/40
on a therapeutic source assembly over 500 kVp, what is the maximum absorbed dose rate due to leakage radiation (excluding neutrons) at any point outside the maximum field size, but within a circular plane of 2 m radius that is perpendicular to and centered on the CAX at the normal treatment distance?
0.2% of the useful beam dose rate at the tx distance
the quality of leakage radiation is approximately the same as the of the ___
primary beam
is leakage radiation more or less penetrating than scattered radiation
more penetrating
unless a maze entryway is provided, the door must provide shielding equivalent to the __ surrounding the door
wall
the __ must be protected against neutrons that diffuse and reach it
door
high energy x-ray beams over __ MV are contaminated with neutrons
10
what is better to reduce neutron contamination– designing a longer maze or adding more lead shielding to the door
designing a longer maze
should brachytherapy sources be touched with your hands?
no long forceps should be used instead
what should be done with a leaking source
a leaking source should be returned to an agency that is authorized for the disposal of radioactive materials
can ionization chambers be used to measure exposure directly
yes
is a cutie pie survey meter an ion chamber? GM counter? or TLD?
ion chamber
is a geiger muller detector more or less sensitive than an ion chamber
more sensitive
does a GM detector measure dose
no
which of the following is best for finding contamination and other low levels of radiation- ion chamber, GM detector, or TLD?
GM detector
is a rascal an ion chamber, GM counter, TLD, or neutron detector
neutron detector
how should radiation transmitted through the primary barrier be measure?
radiation transmitted through the primary barrier should be measured with the beam at max size pointed at the barrier
how should measurements outside the secondary barrier be made
measurements outside the secondary barrier should be made with a phantom in the treatment position
why would film monitor be used instead of a TLD or OSLD?
it’s cheaper
in a TLD what does the crystal substance typically consist of?
lithium fluoride LiF
what does OSLD stand for?
optically stimulated luminescent dosimeters
an OSLD can be read for as long as __ after irradiation
1 year
what acceptance is this (below)?
light beam with x-ray beam coincidence
what is the tolerance for the light beam with x-ray beam coincidence test?
the alignment between the light beam and the x-ray beam should be within +/- mm or 1%on a side
define mechanical isocenter
the intersection point of the collimator axis rotation and the gantry axis rotation
what may be caused by the heavy weight of the gantry frame
the axis of the gantry rotation can miss the axis of the collimator rotation, thereby creating an uncertainty in the position of the isocenter
define wiggler
an adjustable pointer device with a sharp point that may be attached to the distance- measuring rod that is attached to the accessory mount for the purpose of performing a mechanical isocenter check
what is the tolerance for the collimator rotation mechanical isocenter check
for an acceptable alignment, the isocenter should stay within a 2 mm diameter circle when the collimator is rotated through its full range of rotation
what is the tolerance for the gantry rotation mechanical isocenter check
the tolerance of the isocenter motion with full gantry rotation is +/- 1 mm
what do the 3 star pattern tests check
radiation isocenter
with regard to the collimator radiation isocenter test, what is considered an acceptable result
all the lines should intersect or pass within a 2 mm diameter circle
with regard to the treatment table radiation isocenter star pattern test, what is considered an acceptable result
all the line should intersect or pass within a 2 mm diameter circle
with regard to the gantry radiation isocenter test, what is considered an acceptable result
should show the lines intersecting or passing within a 2 mm diameter circle centered around the presumed radiation isocenter
what does the split field test detect
focal spot displacement, asymmetry of collimator jaws, and displacement in the collimator rotation axis or the gantry rotation axis.
what is the tolerance for calibration of leaf positions?
deviation of more than 20% would indicate positioning problems
how can irregularly shaped fields using MLCs be tested?
create a series of typical irregular field shapes using software, then compare that to MLC generated fields by looking at them and radiographing them
what is the tolerance for wedge angles?
wedge angles should be within +/- 2 degrees
