Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Rad Ther Equipment
and Quality Assurance
| Question | Answer |
|---|---|
| In 1 month, the output of a cobalt machine would reduce by about | 1% |
| The protective housing around the cobalt source in the cobalt machine should only allow transmission of ________ of the output. | 0.1 % |
| the target of the linac must have | a high melting point |
| the source of electrons in a linear accelerator is the | electron gun |
| what type of target is used in high energy linear accelerators | transmission type |
| trimmer bars are attached to the collimator of the cobalt machine to reduce the effect of | penumbra |
| which of the following machines does not accelerate electrons? microtron betatron cyclotron xray tube | cyclotron |
| the purpose of the flattening filter in the linac is to | evenly distribute the energy of the photon beam across a specified area |
| what is the purpose of the ion monitor chamber in the linear accelerator? | monitors dose rate and field symmetry |
| what is the purpose for the magnetron and klystron in the linear accelerator? | M- low energy produce microwaves for acceleration of electrons K- high energy units |
| why does the cobalt machine not have an electron gun? | uses radioactive sources not electrons and photons |
| why shouldn't trimmer bars attached to the cobalt collimator system be allowed closer than 15 cm from the patients skin? | allows room for secondary radiation to spread out before reaching patient. |
| As distance form the source increases, penumbra ___________ | increases |
| As the SDD increases, penumbra __________ | decreases |
| As the source size decreases, penumbra ________ | decreases |
| The target in the linear accelerator is typically made of | tungsten |
| The field light on the linear accelerator is intended to represent | the area of radiation exposure |
| the teletherapy cobalt machine has a beam stopper. the purpose of the beam stopper is to | -prohibit the primary beam from penetrating adjacent wall and ceiling - act as a counter-balance to the heavy gantry head |
| the scattering foil is placed in the path of the stream of electrons in the linear accelerator when programmed to operate in the _______beam mode | electron |
| the klystron and magnetron is the source of ___________ in the linear accelerator | microwaves |
| the cyclotron may produce _________ beams | proton ( also neutron and deuterons) |
| the purpose of a positioning device is to | accommodate the most appropriate position for accurate treatment delivery |
| the energy range for the early generation superficial therapy machines is | 50 to 150 kV |
| a long cylinder loaded with radioisotopes and placed in the vaginal space could be used to treat the | vaginal vault |
| the linear accelerator generates a high-energy photon or electron beam by | accelerating charged particles in a linear path |
| Output corrections must be made monthly when using cobalt sources. the correction is about | 1% per month (output 1%) |
| Geometric penumbra, characteristic of the cobalt beam, increases with | increasing source size increasing distance from the source |
| Heyman capsules may be used to treat the | endometrium (look like small tampons) |
| The Fletchers suite application is an example of | intracavitary low dose rate brachytherapy (1 tandem, 2 ovoids) |
| The BAT system uses __________ energy to localize the treatment target | ultrasound |
| The important QA test associated with the light field are | field size accuracy light and radiation field coincidence |
| Functional performance of radiation therapy equipment can | change due to malfunction of system electronics or component fault change due to wear and tear of the equipment |
| the target to patient skin distance is measured using | an OID indicator |
| the collimator, gantry, and couch of a conventional simulator rotate about their respective axes. The recommended tolerance for locating the isocenter in these rotations is a sphere of dimension | 2 mm diameter |
| the tolerance for the localizing laser and the ODI indicator is | 2 mm |
| the constancy of linac output for photon and electron beams must be checked | daily |
| the constancy of linac output, when compared with the benchmark values established during commissioning, must be within | 3 % |
| the symmetry and flatness of the clinical photon beam can be checked using | film a beam profiler |
| the xray beam in the linac must exhibit flatness within about | 2 % |
| scan and couch vertical positional accuracy for CT planning must be | about 2 mm |
| which of the following checks must be carried out daily on the cobalt machine | function of radiation room monitor function of door interlocks |
| cobalt beam output must be checked | monthly (1.09% beam output) |
| full calibration and overhaul of treatment equipment must be carried out | annually |
| in the case of brachytherapy sources | all sourced must be leak tested |
| the exact position of the source in the applicator can be checked by | taking a radiograph |
| brachytherapy sources must be calibrated | before being used for clinical dosimetry by a user using a chamber with calibration traceable to an accredited dosimetry calibration laboratory |
| in a brachytherapy procedure room, the following items must be available all the time | a radiation survey meter a temporary storage container a cutter and long-handled tongs |
| the tolerance for the coincidence of light and radiation field, in the case of the medical linac is | 2 mm or 1% of field length being measured whichever is greater |
| localizing lasers on simulators must be within ________ of isocenter | 2 mm |
| microwave power is produced to accelerate electrons | klystron |
| microwave power is directed toward the accelerator guide | waveguide |
| reference signal is provided for generation of microwave power | modulator radiofrequency driver |
| electrons are produced | electron gun |
| electrons are accelerated to high energy | accelerating guide |
| at the end of acceleration, high energy electrons are focused toward the collimator opening | bending magnet |
| xrays are produced by Bremsstrahlung and characteristic radiation process | target |
| the electron beam is spread out uniformly over the field area | scattering foil |
| xray beam intensity is made uniform over the field size at the isocenter | flattening filter |
| monitors radiation output | ion chamber |
| Monitors radiation beam uniformity by monitoring and controlling symmetry and flatness | scattering foil flattening filter ion chamber |
| produces high voltage and high power electrical pulses to generate microwave power | modulator |
| these components, through which electrons travel, are under very high vacuum | accelerating guide |
| microwaves travel through these components and are prevented from reflecting backward | waveguide radiofrequency driver |
| During a split field test for longitudinal displacement of the collimator for jaw symmetry, the collimator is rotated through an angle of | 180 degrees |
| To check the accuracy of gantry digital readouts one could use | a spirit level at 45 degree angle increments |
| a short exposure is taken on a radiographic film aligned with metallic marks on the borders of a collimated light field. this describes testing for | light field/radiation coincidence |
| the linear scales on the treatment table are useful as an aid for | daily treatment setup translation of patient positions from simulation to treatment |
| safety door interlocks should be checked | daily |
| which of the following verifies the accuracy of radiation dose delivery | back up timer, radiation off switch, door interlock and emergency off switch |
| to ensure the patient's safety during treatment on a megavoltage linear accelerator, the patient must be monitored by | intercommunication systems |
| the process for testing a new accelerator against manufacturer's specifications before putting it into service is termed | acceptance testing |
| a high energy photon unit will require daily quality checks for the determination of | dose rate constancy |
| gantry and collimator indicators should be accurate to within ____ | 1 degree |
| the common acceptable value for field flatness is about ___________ over the central 80% of the largest field size at isocenter | 3% |
| all of the following might account for a beam's flatness deviating outside specifications, except: flattening filter shift target position shift incorrect mirror angulation fluctuation of current | incorrect mirror angulation |
| While treating a patient using a rotational arc technique, the gantry rotates beyond the endpoint. this is likely a malfunction of the | limit switch |
| a mechanical distance indicator is used to verify | accuracy of optical distance indicator |
| if the mirror and bulb assembly has to be replaced, it is critical to perform the following quality check before using the machine | light field and radiation field coincidence |
| the average gamma energy for cobalt is | 1.25 MV |
| superficial therapy machines used short treatment distances because | percent depth dose falls off rapidly |
| in early generation kV therapy machines, the quality of the photon beam could be increased by | increasing the filtration |
| OBI is an acronym for | onboard imaging |
| the machine that consists of a short metallic cylinder divided into two D-shaped cavities is known as the | cyclotron |
| the gantry head of the linear accelerator contains all of the following except: flattening filter ion chamber xray target klystron | klystron |
| Cesium-137 | half life- 30 years source form- tubes, needles applications- LDR intravitary, interstitial |
| Iridium-192 | half life- 73.8 days source form- seeds applications- LDR interstitial, HDR interstitial, and intracavitary |
| Cobalt-60 | half life- 5.26 years source form- encapsulated spheres applications- HDR intracavitary |
| Iodine- 125 | half life- 60 days source form- seeds applications- Interstitial |
| Palladium-103 | half life- 17 days source form- seeds applications- interstitial |
| Gold- 198 | half life- 2.7 days source form- seeds applications interstitial |
| Strontium-90 | half life- 28.9 years source form- plaque applications- superficial ocular lesions |
| Strontium-89 | half life- 51 days source form- IV solution applications- diffuse bone metastates |
| Iodine-131 | half life- 8.06 days source form- capsule applications- thyroid cancer |
Created by:
shelbybrynngomez