D.treatment machine accessories E.tratment application Flashcards
_____are meant to create a homogeneous isodose distribution within the patient
Compensators
Two types of compensators include :
missing tissue compensators and dose compensators
A ____tissue compensator makes up for a sloping skin surface and creates a more homogeneous dose distribution
missing
A ____compensator makes up for missing tissue and inhomogeneities in the patient’s anatomy
dose
_____:are Used during electron therapy to shield critical structures that are located directly behind the tumor being treated
Internal shields
______: Limit a certain percentage of the beam to pass through at a certain location within the treatment field
Transmission filters
___: Premade shields created with a high-density material. » Not customized for each patient
Hand blocks
_____: Shields that are individualized for each patient » Can be created into almost any shape
Cast blocks
______is made up of 50 percent bismuth, 26.7 percent lead, 13.3 percent tin, and 10 percent cadmium W/ Ctl•ase
Cerrobend
Cerrobend has a lower melting point than lead and melts at
740C (1650F)
Allowable transmission of the radiation beam through the cast block is less than
5 percent
Blocks used with photon beams should be placed at a minimum of ___ cm from the surface of the patient
20cm
The thickness of Cerrobend blocks ranges from
6 to 8 cm
_____ are blocks that shield more of the central part of the radiation field, leaving the periphery open » Example: lung blocks
Positive blocks
_____are blocks that shield the periphery of the radiation field and the central portion is open » Example: electron cutouts
Negative blocks
____ Reduces the need for cast blocks
MLCs`
Leaf width varies from ____Cm
0.4 to 2.0 cm
The ____the width of the leaf, the more conformal the shape of the beam can be
narrower
____is possible with the use of MLCs
IMRT
_______: The beam is delivered with MLCs in one stationary position, turned off as the MLCs reposition to the next segment, and then turned back on
Step and shoot
______: The beam remains on as the MLCs move throughout the treatment
Dynamic
____is used to eliminate skin-sparing effects in photon therapy, compensate for irregular surface contours, and eliminate air gaps in treatment fields
Bolus
Examples of bolus material are
superflab, paraffin wax, Vaseline gauze, etc.
___are used to alter the isodose distribution based on the patient’s skin
Wedges