Chapter 8 PP

Question 1

what are the two verify and record systems used at our clinical sites

Answer 1

aria & mosaiq

Question 2

what are the two types of lasers

Answer 2

red or green helium (HeNE) neon lasers

Question 3

which color laser projects more sharply

Answer 3

green

because they have a shorter wavelength causing less scatter on the skin

Question 4

what is the type of couch currently used

Answer 4

carbon fiber

Question 5

what was the previous couch that was used

Answer 5

mylar

Question 6

which couch can you see through

Answer 6

mylar

Question 7

POP field

Answer 7

parallel opposed portal

Lt/Rt lateral or AP/PA

Question 8

tangents field

Answer 8

opposing field for supericial volumes on curved surfaces which has flash off of the patient

Question 9

four field box field

Answer 9

fields are arranged 90 degrees from one another

Question 10

arc therapy

Answer 10

radiation is delviered while the gantry moves through its arc of rotation

Question 11

conformal treatment technique

Answer 11

delivers a uniform dose to structures in the beam path

Question 12

IMRT treatment technique

Answer 12

delivers a nonuniform dose across the beam path

Question 13

2 methods of IMRT

Answer 13

step and shoot

sliding window

Question 14

VMAT (volumetric modulated arc therapy)

Answer 14

delivers IMRT vial rotational arc, multiple MLC positions and changing dose rate, further conforming dose delivery to the tumor volume and acoiding organs at risk

Question 15

electron technique

Answer 15

superficial treatment

Question 16

common prescription changes include change in: (4)

Answer 16

of factions
total dose
bolus
beam apertures

Question 17

the rad therapist should review the prescription __________ each treatment as the oncologist may have made changes from the previous day

Answer 17

immediately before

Question 18

what should be reviewed in the treatment plan? (5)

Answer 18

field sizes 
beam modifiers
depths (SSD)
dose measurement (diodes)
gantry angles

Question 19

examples of treatment techniques

Answer 19

IMRT
3D conformal 
POP
four field box
tangents

Question 20

The point of intersection of three axes of machine rotation (gantry, collimator, and base of couch)

Answer 20

isocenter

Question 21

Are any fixed reference points against which other objects can be measured.

Answer 21

fiducial markers

Question 22

fiducial markers can be at the (3)

Answer 22

skins surface, fixed external to the patient, or internal

Question 23

Two images taken perpendicular to one another, with a 90 degree angle between them.

Ex. AP and Rt. Lateral, AP and Lt. Lateral, PA and Rt. Lateral, PA and Lt. Lateral

Answer 23

orthogonal images

Question 24

what imager is used for orthogonal images

Answer 24

KV

Question 25

what are orthogonal images used for

Answer 25

to verify isocenter

Question 26

__________ verify the BEV path, including the beam shape, position, and projection of the beams central axis

Answer 26

portal images

Question 27

what treatment beam is used for portal images

Answer 27

MV

Question 28

most sites do portal iamging _________

Answer 28

once a week

Question 29

At clinic will often take two exposures:

Answer 29

planned one and an open one (double exposure)

Question 30

______________ allows therapists to see surrounding anatomy, increasing the landmarks for interpretation

Answer 30

open exposure

Question 31

open exposure is made after the removal of

Answer 31

the field-shaping devices and the collimator jaw retraction

Question 32

When wedges are used, the _______ are typically positioned together.

Answer 32

heels

Question 33

Wedges reduce the dose in areas of overlap between fields that have a hinge angle less than ____.

Answer 33

180 degrees

Question 34

The thick end of the wedge is the heel and it attenuates the________ amount of radiation, drawing the isodose lines _______ to the surface.

Answer 34

greatest; closer

Question 35

The thin end of the wedge is called the_____ which is where the dose delivered to the patient will be relatively ______ than the dose at the opposite side of the treatment field.

Answer 35

toe | greater

Question 36

All beam-shaping and modification devices for photon beams must be secured a minimum of _____ from the surface of the patient. why?

Answer 36

20 cm The interaction of the photon beam with materials produces scatter electrons that contaminate the photon beam and produced increased skin does for patients. Low-energy electrons are absorbed in approximately 15cm of air.

Question 37

rather than a physical wedge being used, dynamic jaws and MLCs can be used to configure for movement through beam delivery accomplishing what a physical wedge would have done.

Answer 37

dynamic wedge

Question 38

the side of field at which the jaw starts its movement receives _______ exposure, correlating with the ________.

Answer 38

more wedge toe

Question 39

In general, if something is placed in the path of the beam, the number of MUs will need to be ______ to deliver the prescribed dose

Answer 39

increased

Question 40

the _______ within the head of the gantry measures the radiation output

Answer 40

ion chamber