Ch 7: Tteatment Delivery Equipment Flashcards
What is the half life of cobalt-60
5.26 years
What is the source to axis distance for a Co-60 treatment unit?
80cm
Co-60 images have _______(more/less/same) penumbra than images taken on a Linac.
More
Photon treatment with a Linac exhibit ______(more/less/same) skin sparring than more traditional units
More
Most treatment couches allow for ___ degrees of freedom
4
This/these device provide the microwave power to Linac
Klystron and magnetron
This structure directs the microwave power toward the accelerator structure
Circulator
The length of this structure depends on the energy capability of the machine
Accelerator structure
______ is used in photon mode/tx while _____ is used in electron mode/tx
Flattening filter; scattering foil
This device monitors the flatness and symmetry of the beam
Ion chamber
Linacs, Van de Graaf generators, Betatron, Cyclotron and cobalt-60 are examples of…
High energy units (mega voltages)
T/F
Linear accelerators give better dose distribution, faster dose rates, and is more manageable radiation protection.
True
Treatment time increased as source decay. Which high beam unit is this?
Cobalt-60
The fuzzy edge of the radiation beam is known as?
Penumbra
T/F
Increased in penumbra is found with a Linac
False. More penumbra with cobalt 60
We call our machines linear accelerators because we accelerate electrons near the rate of ___________.
Speed of light in a straight line
SAD is also Called the _____technique
Isocentric
What is skin sparing
The deeper the radiation penetrate the body, the less reaction you’re going to have at the skin
Why are linac more preferable over cobalt 60?
Because it’s more accurate and cosmetically favorable due to the increase in skin sparring
The drive stand houses what 4 major components?
Klystron/magnetron
Waveguide
Circulator
Cooling system
Major components of the Linac
Drive stand
Gantry
Treatment couch
Varian: drive stand is ______ room
Inside
Elekta: driver stand is _______ room, behind _______
Outside; walls
Semins: drive stand is _______ room
Inside
What are CCTV and their purpose?
CCTV: closed circuit TV are cameras placed inside the treatment room to monitor the patient indirectly
Lead walls or ______ ______ is used to stop radiation
Thick concrete
The couch has 6 degrees of freedom. What are they
Lateral Longitudinal Rotation Pitch Roll Vertical
What are the components of the gantry (3)
Electron gun
Accelerator guide
Accelerator structure
_______ provide the microwave source
Klystron/magnetron
_________ prevent black flow of microwaves by punching the microwaves forward
Circulator
_________ allows the gantry and components to operate at a constant temp. Linacs uses cold water
Cooling system
_____ produces the electron and injects the electron into the accelerator structure
Electron gun
_______ transport microwave power to the accelerator structure
Accelerator guid
The _________ amplifies momentum of the electron stream, speed the electron to the speed of light and can range from 30cm to 1m
Accelerator structure
T/F
The length of the accelerator structure is dependent on the bea energy
True
To deactivate the beam, you could
Turn the key
Open the door
Push “beam interrupt”
What’s the max field size for modern linac
40 x 40
The backup or secondary ion chamber is set to terminate the beam with ______ number of MU than primary chamber
A higher due to beam pulsating
Photon treatments with linac exhibit _____ skin sharing than tradition
More
The length of this structure depends on the energy capability of the machine
Accelerator structure/guide
This structure directs the microwave power toward the accelerator structure
Waveguide
What’s the depth of Dmax for a 10 MV beam ?
2.5
This device monitors the flatness and symmetry of beam
Ion chamber
What’s the Dmax for a 4MV beam
1.0cm
What’s the first thing you should do if the beam fails to terminate
Push the beam interrupt (beam off) button
Most linear accelerators have horizontally mouthed accelerators guides
True
Wedges
Changes the isodose distribution
As energy increases, depth of electron equilibrium (Dmax)
Increases
Output of a combalt 60 is measured in terms of
Minutes and seconds
A no harm incident is one in which…
An event reached the patient but the patient was not injured
