Final Prep Flashcards
Provides the source of the microwave power used to accelerate electrons (housed in drive stand)
Klystron
Carries microwave power from Klystron to accelerator guide (housed in drive stand)
Waveguide
Placed between the klystron and waveguide to direct the RF energy into the waveguide and prevents any reflective microwaves from returning to the klystron. This allows the klystron to last longer (house in drive stand)
Circulator
Allows components in the gantry and drive stand to operate at a constant temperature. (housed in drive stand)
Cooling System
Responsible for producing electrons and injecting them into the accelerator structure. (Gantry)
Electron Gun
Sometimes called the accelerator waveguide. Microwave power is transported to the accelerating waveguide, in which corrugations are used to slow the waves. (Gantry)
Accelerator Structure
One of the electrodes in the x-ray tube (negative side) Consists of the filament and focusing cup. Primary function is to produce electrons and focus the electron stream toward the metal anode. (Gantry)
Cathode (Remember Negative)
Positive side of the X-ray tube. Receives electrons from the cathode as a target, dissipates the heat as a result of the x-ray production and serves as the path for the flow of high voltage. (Gantry)
Anode (Remember Positive)
Directs the electrons vertically toward patient on the table. Otherwise the electrons would continue straight out, horizontally thru the treatment head of the gantry. (Treatment head)
Bending Magnet
Monitors beam dosimetry to within 2% for long-term consistency and stability. (Treatment Head)
Ion Chamber
It is located on the carousel with the scattering foil. Placed in beams path when treating with x-rays to shape the x-ray beam in it cross-sectional dimension (Treatment head)
Beam Flattening Filter
The purpose of this foil to broaden the pencil-like electron beam and produce a flat field across the treatment field. (Treatment head)
Scattering foil-used in electron mode (used matches the electron energy called)
This is the point at which x-ray photons are produced and begin to fan out in a divergent path (Treatment head)
Target (portion of the anode)
An arrangement of shielding material designed to define the X and Y dimensions of the beam of radiation. (Treatment head)
Collimators
How did the Linear Accelerator get it’s name
Electrons or charged particles travel in a straight line (within tube) Gantry
What is produced in X-ray mode and what filter is used in the carousel?
Photons and a Flattening Filter (X-ray mode has to hit a target)
What does the Scattering foil produce
Electrons
The carousel will continue to rotate until the opening allows the scattering foil to open?
True
What are the advantages of KV images
- Better detailed (better contrast)
- Provides more info about soft tissue and bony anatomy
- Less dose to patient than MV imaging
What Orthovolotage image is used to verify portal
MV image
System producing real-time portal images on computer screen for evaluation
Electronic portal imaging device
Created during the simulation
DRR (Digitally reconstructed radiograph)
Acquires many projections over the entire volume of interest as the gantry rotates around the patient. (The gantry rotates around the patient taking images the entire time it is rotating using the KV images system)
CBCT imaging (Cone Beam CT)
Area or region at the beams edge where the radiation intensity falls to 0
Penumbra
What are the two verify systems used within our program during clinical’s
Aria and Mosaiq
Provides valid parameters from the treatment plan to the treatment machine for setup and delivery. Compares the actual machine settings with those prescribed for a particular filed and prevents beaming on if the settings are not within the specified tolerance ranges
Record and Verify system
Individual treatment dose
Fractionation
Time period during which the treatment will be given
Protraction
Changes occurring between treatment sessions
Interfraction (examples: Prostate treatment, patient did not drain bladder completely and or have a empty rectum.
Safety switches blocking or terminating radiation production. Prevent beam initiation and include alerts prompting completion of treatment setup and safety procedures, including closing the door, beam-modifiers placement such as wedges and electron cones.
Interlocks-Safety switches
________ will prevent initiation of beam if water temp, water pressure, and vacuum system measurements not in range.
Interlocks-Safety switches
Suffix for (Intra)
Within
Suffix for (Inter)
Between
The arrangement of shielding material designed to define the x and y dimensions of the field
Collimation
The measure of the angle between central rays of two intersecting treatment beams.
Hinge Angle (ex: POP fields have a hinge angle of 180 degrees)
A standardize approach to verify that you are treating the right patient, area, etc. (Example: Patient is on the treatment couch and the therapist says: “we are treating Jon Smith”)
Time Out
Used to modify the dose distribution across the beam accommodating for the patients contour
Compensators ( example: Bolus, Wedge)
Is the cpmpensator that goes into the head of the gantry is skin sparring unlike bolus
True
A moving jaw starts at one side of a treatment field and opens to the full field over the beam exposure. The dose is effectively sloped over the field, in the manner of a physical wedge.
Virtual Wedge
When you make shifts on the patient/or to treatment couch, when reviewing the council screen are you reviewing the plan or the actual?
Actual
What is the minimum x-ray beam energy required for a radiation therapy machine to be classified as a megavoltage machine?
1MV
Is the control console located inside or outside of the room
outside
Gross palpable or visible tumor
GTV- Gross Tumor Volume
GTV plus any margin of subclinical disease that needs to be eliminated thru the treatment planning process
CTV- Clinical Target Volume
CTV plus margins for geometric uncertainties such as patient motion beam penumbra and treatment setup differences.
PTV- Planning Target Volume
Calibrated so that 1 MU delivers 1cGy for a standard reference field size (usually 10x10) at a standard reference dept at a standard source to calibration point.
MU-Monitor Units
Unit of energy absorbed per unit mass of any material
cGY (centigray)
Measurement of the thickness of a patient along the central axis or at any other specified point within the irradiated volume
Sep (Separation Measurement)
Suffix for Treatment
Tx
Suffix for Fraction
Fx
Suffix for Field Size
FS (Field size dimensions of the treatment field a the isocenter)
What is EPID
Electronic Portal Imaging Device- system producing near real-time portal images on a computer screen for evaluation
What is a DRR and when is it created?
Digitally Reconstructed Radiograph/ During simulation
What is IGRT and what is the rationale for using it?
Image Guided Radiation Therapy- To image the patient before treatment and compare the position of external setup and marks and internal anatomy with the treatment plan. (Image can detect: weight loss, respiratory motion, movement of body or internal structures and tumor shrinkage)
What are MLC’s, where are they found and what are they used for
Multileaf Collimator- gantry head- shaping or blocking the field shaping
What is the range finder used for on the gantry head
Used to read the SSD- the projects onto the patients skin and match the intersecting crosshairs that coincide with the central ray of the beam.
MLC’s do not move while the beam is on
Static
MLC’s are moving while the beam is on
Dynamic
When treating a patient with skin cancer and using electrons, does the electron beam strike the x-ray target in the treatment head
NO
When treating a patient with skin cancer and using electrons, which foil is used?
Scattering Foil
What is used in the treatment head to allow the therapist to set the field size for each patient?
Collimator Jaws
Lining the patient up to the three points marked on the patient using the three machine- aligned lasers
Triangulation
The arrangement of shielding material designed to define the x and y dimensions of the field
Collimation
While treating a patient should the the lights be on or off
On
List two methods for identifying a patient
- picture in the chart
- wrist bracelet
- name
- date of birth
- last 4 of social
Will the three point localization marks placed on the patient for triangulation will always coincide with the treatment isocenter
False
What is a portal image
Port Film
An image that verifies that BEV path, including the beam shape, position and projection of the beams central axis
Portal Image
What else can be used as a bolus?
Paraffin Wax, Vaseline gauze, wet gauze or towels, superflab and water bags
What are compensators used for?
To modify the dose distribution across the beam accommodating for the patients contour
The thin end of the wedge is called _______ and the thick end of the wedge is called __________
toe/heel
What are the (4) standard wedge sizes
15, 30, 45, 60
What is the name of the wedges placed in the gantry head?
physical wedges
What is commonly used to treat prostate?
Four Field Box
An AP/PA and two lateral fields are often referred to as a _________?
Four Field Box
IMRT technique where the leaves reposition then come to rest while the beam is delivered in multiple segments at each gantry angle.
Step and Shoot
IMRT technique where the MLC’s move from one side of the field to the other wile the beam is on.
Sliding Window
IMRT allows a _______ dose to be delivered to the target while delivering _______ dose to the normal structures around it.
High/Low
Side Effects of Prostate Cancer
Decrease urinary stream (Slow growing/Risk
Frequency increases with age)
Difficulty starting to urinate
Painful Urination (dysuria)
Blood in Uria (Hematuria)
When treating the whole brain what are the boarder you watch out for?
Supra orbital ridge, EAM (external auditory meatus) Mastoid Process and C1/2
When treating the whole brain what is the collimator set to treat the patients right side if the patient is supine?
45 degrees (Left would be 315 degrees)
What do you check before treating whole or helmet brain cancer?
1cm of flash
Helmet Brain Prescription
3000cGy/300cGy fx/10 fx/ 6mv/ midplane
What field are you using when treating a Helmet or Whole Brain?
POP Field- parallel opposing Field (180 degrees)
What is the most common sign of Metastasis to the brain?
Headaches
What are the signs of Metastasis to the brain?
- headaches
- seizures
- dizziness
- difficulties with balance
- mental and personality changes
What are the common PRIMARY cancers that spread to the brain?
- lung
- breast
- gastrointestinal
- head/neck
- prostate
- melanoma
Brain mets occurs in about 25% of patients with cancer
Small Cell Lung Cancer has such a propensity to spread to Brian that patients are usually with ___________
Prophylactic Cranial Irradiation (PCI)
What does the Z shift do to the table
Moves the table UP and Down