Final Review Flashcards
how often should the block room be assessed with air sample analysis?
annually
how often should a chart check be performed?
- before treatment delivery
- weekly
- at treatment completion
kV-CBCT and MV-CBCT: how often should the collision/door interlocks be checked?
daily
kV-CBCT and MV-CBCT: how often should laser image treatment isocenter coincidence be checked?
daily
T/F: treatment charts are legal and binding docs that can be entered into a court of law.
true
what the tolerence for laser image treatment center coincidence?
+/- 2mm
CT sim: what is the tolerance for the adjustment of gantry lasers with center of imaging plan
2mm
CT sim: what is the tolerance for the spacing lateral wall lasers with respect to lateral gantry lasers
2mm
Describe linac acceptance testing (hint: 3 things).
- Involves measurement of output & performance of the linac against manufacturer specs
- Establishes baseline values that are used in future dosimetric measurements
- Verifies that the machine operates within certain tolerances & mechanical integrity
Daily QA: what’s the tolerance of x-ray output constancy
all energies
3%
Daily QA of laser localization: whats the tolerance for Non-IMRT?
2mm
Daily QA of laser localization: whats the tolerance for IMRT?
1.5 mm
Daily QA of laser localization: whats the tolerance for SRSBRT?
1 mm
Daily linac QA of ODI at isocenter: what is the tolerance for Non-IMRT?
2 mm
Daily linac QA of ODI at isocenter: what is the tolerance for IMRT
2 mm
Daily linac QA of ODI at isocenter: what is the tolerance for SRSBRT
2 mm
on a linac how often must we check that the beam turns off when you open the door?
daily
How often must the AV monitors be checked?
daily
How often must the radiation area monitors be checked?
daily
How often must the beam on indicator be checked?
daily
whats the tolerance for the electron beam constancy?
2% or 2mm
what is the tolerance for light radiation field coincidence?
2 mm or 1% on a side
what is the tolerance for distance check device for lasers compared with front pointer?
1 mm
what is the tolerance for cross hair centering?
1 mm
what is the tolerance for treatment couch position for Non-IMRT?
2 mm or 1 degree
what is the tolerance for treatment couch position for IMRT?
2 mm or 1 degree
what is the tolerance for treatment couch position for SRSBRT?
1 mm or 0.5 degree
on a linac how often must the latching of wedges be checked?
monthly
whats the tolerance for tabe angle?
1 degree
whats the tolerance for table top sag?
2 mm from baseline
which test looks at deviations in interleaf transmission?
picket fence test
What does VMAT stand for?
volumetric modulated arc therapy
is the treatment room a controlled or uncontrolled area?
controlled
is the bathroom a controlled or uncontrolled area?
uncontrolled
is the treatment console area controlled or uncontrolled?
controlled
is the exam room a controlled or uncontrolled area?
uncontrolled
is the waiting room a controlled or uncontrolled area?
uncontrolled
what’s the max dose equivalent for a controlled area?
0.01 mSv/ wk (5 mSv/yr)
what’s the max dose equivalent for an uncontrolled area?
0.02 mSv/ wk (1 mSv/yr)
a barrier sufficient to attenuate the useful beam to the required degree is known as?
primary barrier
the required barrier that protects against stray radiation (leakage and scatter) is known as?
secondary barrier
what factors enter into the calculation of barrier thickness?
workload
use factor
occupancy factor
distance
what is the definition of workload?
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 1m
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
how is workload expressed?
dose / wk at 1m
in the calculation of barrier how is distance measured?
meters from radiation source to the area to be protected
what is the occupancy factor for areas occupied full time?
1
what is the occupancy factor for treatment volt doors?
1/8
what is the occupancy factor for the patient exam room?
1/2
what is the occupancy factor for employee lounges?
1/5
what is the occupancy factor for public toliets?
1/20
what is the occupancy factor for unattended parking lots?
1/40
T/F: the quality of leakage radiation is approximately the same as the primary beam?
true
Unless a maze entryway is provided, the door must provide shielding ________ to the wall surrounding the door.
equivalent
Is leakage radiation more or less penetrating than scattered radiation?
more penetrating
are concrete barriers designed for x-ray shielding sufficient for protection against neutrons?
yes
Which of following x-ray beams is contaminated with neutrons?
10 MeV
What is better to reduce neutron contamination – designing a longer maze or adding more lead shielding to the door?
longer maze
Which of the following helps minimize personnel exposure to brachytherapy sources? A. using long forceps B. Mobile protective shields C. Using low E sources D. Using radium
A, B, C
A source is considered to be leaking if there is presence of ____ microcurie or more of removable contamination is measured.
0.005
Which of the following can be used to measure exposure directly?
ionization chamber
Cutie pie is an example of:
ion chamber
Which of following is best for finding contamination in other low levels of radiation?
G-M detector
A Rascal is example of:
neutron detector
The film in a film monitor cannot be read after how long?
6 months
Which of the followings is least expensive?
film monitor
T/F: Thermoluminescent Dosimeter are strictly for personnel use, cannot be used with pt under treatment.
False
How often can a TLD be read?
once
T/F: OSLD are strictly for personnel use, cannot be used with pt under treatment.
false
OSLD can be read for as long as _____ after irradiation.
1 year
What kind of check is the star pattern test?
radiation isocenter
What kind of check is the split field test?
multiple beam alignment
Mechanical iso is defined as the intersection point of:
Collimator access rotation and gantry access rotation
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:
wiggler
What’s the tolerance for collimator rotation mech iso check?
2 mm diameter circle (when you have something bigger than that then is a prob)
What is the tolerance for the gantry rotation mech iso check?
+/- 1mm
what is the tolerance for the star pattern test?
All lines should intersect or pass within a 2mm diameter circle
T/F: When performing a star pattern test, all slit images should ideally intersect at one point of rad iso.
True
what does the split field test detect?
- Focal Spot Displacement
- Asymmetry of Collimator Jaws
- Displacement in the Collimator Rotation Axis or the Gantry Rotation Axis
The split field test consists of double exposing a film to 2 fields ___ apart.
180°
What is the tolerance for calibration of leaf positions
Deviation of more than 20% will indicate positioning problems
What is the tolerance for wedge angles?
± 2ۣ°
Leakage of radiation between collimator leaves in a close position is:
a bad thing
Which of the terms below matches following steps?
- Before a linac can be used or pt treatment it must be calibrated and all the beam data and treatment parameters must be obtained
- These data is then put on treatment computer
- The computer generates dose distributions…….
commissioning
How often should leak test of brachytherapy sources be performed?
every 6 months
Commissioning of a linac is the responsibility of:
medical physicist
Computer software should be commission for each treatment machine and E and must be updated
anually
If pt treatment plan has not been reviewed by an oncologist and physicist before the first treatment it needs to be reviewed before:
3rd frac or before 10% of dose has been delivered
The radiation dose that is delivered should be within ___ of the prescribed dose.
5%
The annual QA report should be verified by:
medical physicist
Defined as the transverse variation of dose relative to the central axis over the central 80% of the field size at 10-cm depth in a plane perpendicular to the CAX:
field flatness
What is the acceptable dose variation for field flatness:
+/- 3%