F. elements of machines used in radiation therapy

Question 1

The main parts that make up the linear accelerator are the

Answer 1

drive stand, gantry, treatment couch, console, electronic cabinet, and modulator

Question 2

The______ contains the klystron, waveguide, circulator, and cooling system

Answer 2

drive stand

Question 3

________ Prevents the linear accelerator from overheating

Answer 3

water-cooling system

Question 4

the _____directs and aims photons to the patient

Answer 4

gantry

Question 5

The three parts of the linear accelerator that can move are the gantry, collimator, and couch and they All rotate around the

Answer 5

isocenter

Question 6

Most newer linear accelerators are calibrated to ____ SAD

Answer 6

100 SAD

Question 7

A linac starts with a power supply, which provides ____ to the modulator

Answer 7

direct current (DC)

Question 7

The ____ powers the microwave source (magnetron or klystron) and electron gun

Answer 7

modulator

Question 8

Sources of microwaves in a linear accelerator come from a

Answer 8

klystron or a magnetron

Question 9

Linear accelerators have either a klystron or a magnetron never

Answer 9

both

Question 10

______are injected into the waveguide to accelerate electrons

Answer 10

microwaves

Question 11

_____: Amplifies microwaves

Answer 11

Produces microwaves with a higher power than a magnetron
Used in linear accelerators that produce energies above 12 MV

klystron

Question 12

_____: Stops microwaves from being reflected and reentering the klystron

Answer 12

circulator

Question 13

____ : Generates microwaves
Used in machines that only require low energies

Answer 13

magnetron

Question 14

The circulator is Located between the

Answer 14

klystron and waveguide

Question 15

______: Generates electrons and sends them into the accelerator (waveguide) » Made of tungsten

Answer 15

electron gun

Question 16

Electrons start at 50 keV, but then accelerate as they interact with

Answer 16

microwaves

Question 17

____: Tube where electrons flow to the gantry under a vacuum

Answer 17

Accelerator structure

Question 17

Accelerator structure is a Copper tube with copper discs/diaphragms inside with varying apertures and spacing between each

Answer 17

disc

Question 18

Accelerator structure uses microwaves from klystron to

Answer 18

accelerate the electrons to the target

Question 19

________: Used to bend electrons 90 to 270 degrees to aim them toward the target » 270-degree magnet system creates a more confined beam than the 90-degree magnet system

Answer 19

magnet system

Question 19

Accelerator structure Contains sulfur hexafluoride (SF6) to prevent

Answer 19

arcing in the waveguide

Question 20

________: Where the beam shape is formed and the beam output is monitored

Answer 20

treatment head

Question 21

In photon therapy the components used in the treatment head are (in order):

Answer 21

target, fixed primary collimator, beam-flattening filter, ion chambers, secondary movable collimators, and slots for wedges, blocks, and compensators

Question 22

Flattening filters are made of

Answer 22

lead, tungsten, uranium, steel, or aluminum

Question 23

_____ are small chambers located in the path of the radiation beam and check the beam’s dose rate and symmetry

Answer 23

IOn chambers

Question 24

Most ion chambers are sealed and will not be affected by

Answer 24

temperature or preassure

Question 25

Secondary, _________ can create rectangular fields with sizes ranging from O x 0 cm to 40 x 40 cm at isocenter (usually 100 SAD)

Answer 25

movable collimating jaws

Question 26

In _______ the components used in the treatment head are similar, but scattering foils are used instead of the target and flattening filter

Answer 26

electron therapy

Question 27

______ spread out the 3 mm pencil electron beam to a larger area suitable for treatments

Answer 27

Scattering foils

Question 28

Scattering foils are Typically made of a

Answer 28

thin metallic foil (lead)

Question 29

The CT simulator consists of the

Answer 29

CT scanner, a flat couch top, a virtual simulation workstation, and a laser marking system

Question 30

The CT scanner obtains volumetric images of the patient, which are used for

Answer 30

treatment planning

Question 31

There are multiple generations of CT scanners, but the most current has a

Answer 31

rotating x-ray tube with a fixed ring of imaging detectors (internal components)

Question 32

External parts of the CT gantry are the controls for

Answer 32

couch movements, gantry tilt, emergency off buttons, and localizing lasers

Question 33

Current machines use _______(continuous x-ray rotation while the couch moves in or out during image acquisition)

Answer 33

helical scanning

Question 34

CT simulators for radiation therapy have a ____ bore than conventional CT (70 - 85 cm)

Answer 34

larger

Question 35

The larger bore size allows for _________to fit

Answer 35

positioning and immobilization devices

Question 36

Larger bores allow for a larger scanned

Answer 36

field of view

Question 37

The couch in the CT simulator must be identical to the couch used in the

Answer 37

treatment room

Question 38

An ______ system is used to create reference marks on the patient

Answer 38

external laser

Question 39

what is a pixel in CT

Answer 39

(picture element) - each cell within the matrix

2D representation of tissues

Question 40

what is a voxel in CT

Answer 40

3d representation of tissues

-pixel x slice thickness

Question 41

what is a matrix

Answer 41

layout of cells (pixels) in rows and columns

Question 42

compared to diagnostic CT radiation CT have

Answer 42

-flat table top
- large bore apertures - 70 cm length

• external lasers
• immobilization
• virtual sim software