Vocab List Flashcards
Tumor
Abnormal growth of tissue resulting from uncontrolled progressive multiplication of cells that serves no function.
D-max
The depth at which electronic equilibrium occurs for photon beams. Depth of maximum absorbed dose and ionization photons in a treatment field.
Given Dose
Dose delivered at the depth of D-max through a single treatment field.
Monitor Unit
Unit of output measure used for linear accelerations.
1 mu= 1cGy
Isocenter
Point of intersection of 3 axis of rotation of treatment unit.
- Gantry
- Couch
- Collimator
Central Axis
Central portion of the beam, emanating from the target. Does not diverge.
SSD set up
Distance from source to patient’s skin
SAD set up
Distance from source to axis of rotation of the treatment unit.
Collimator field size
Open field size, projected at a reference distance, usually isocenter (100cm)
Blocked (Effective) Field Size
Equivalent rectangle field dimension of the open treatment area within the collimated field.
Photon Energy
Small pocket of electromagnetic energy.
Electron Energy
Negatively charged subatomic energy that can be accelerated by a variety of machines or can be admitted from decaying isotopes.
Wedge
Tool that modifies the asides distribution of a beam to correct for tissue in homogeneities.
Compensating Filter
Correct for tissue and homogeneities.
Cerrobend Block
Used to form (shape) the treatment field. 50% Bismuth 26.7% Lead 13.3% Tin 10% Cadmium
MLC
Distinct part of a linear accelerator that allows treatment field shaping through the use of motorized leaves in the head of the machine.
Electron Applicator (Cone)
Extended metal structure ised to restrict the useful beam to the required size.
Bolus
Tissue equivalent material placed on the skin to increase skin dose and even out irregular contours on the patient.
Beamsplit
Allows part of the beam to pass through while reflecting the other part of the beam.
Alpha Cradle
Immobilization devices, made from styrofoam.
Aquaplast
Thermoplastic immobilization device.
Bite Block
Used to helo immobilize and help position the tongue.
Positioning Lasers
Used to set up the patient correctly.
Single Field
treat the patient with one field
Parallel Opposed Field
Paid of fields directed along the same axis, form opposite sides.
Tangential Field
Two oblique fields, similar to a breast bridge.
distance from midline to lateral portion
Rotation/ Arc Therapy
Isocentric technique when beam moves continuously about the patient.
Brachytherapy
Uses radioactive material to deliver dose administered directly into the tumor.
Isodoses
Shows distribution of absorbed dose in points of equal dose.
Critical Organ Dose
Organs that limit the dose or the dose that can be tolerated by critical sructures.
OAR
Organs at Risk
Gap
The distance between the borders of two adjacent fields usually measured on the patient’s skin. Used to measure and verify the depth of two adjacent fields.
Image Guided Radiation Therapy (IGRT)
The use of imaging to compare the position of external set up marks and internal anatomy to the treatment plan.
Intensity Modulated Radiation Therapy (IMRT)
Delivers nonuniform exposure across the beam’s eye view using a variety of techniques and equipment.
Volumetric Modulated Arc Therapy (VMAT)
A type of specialized IMRT where VMAT delivers radiation by rotating machine through 1 or more arcs while radiation is continuously delivered.
Tomotherapy
Type of rad therapy in which the radiation is delivered slice by slice.
Linear Accelerator
Radiation Therapy treatment unit that accelerates electrons and produces x-rays and electron treatment.
