Deck 7: Treatment Delivery Equipment

Question 1

A bending magnet in an accelerator may be used:

A) to help deflect microwave power
B) to deflect (bend)the electron beam
C) gather stray electrons together in a bunch
D) gather random paper clips

Answer 1

B
A bending magnet deflects electrons 90 to 270 degrees toward the target.

Question 2

Which of the following best describes the order in which electron bunches and the resulting x-rays travel through the head of a linear accelerator?

A) bending magnet,dose chambers,target,flattening filter,wedge
B) bending magnet,target,dose chambers,primary collimator,wedge,flattening filter
C) bending magnet,target,primary collimator,flattening filter,wedge,dose chamber
D) bending magnet,target,primary collimator,flattening filter,dose chamber,MLC
E) bending magnet,dose chambers,target,flattening filter,primary collimator,MLC

Answer 2

D
The bending magnet directs the electrons toward the target.The photons created are collimated by the primary target,then the flattening filter.Once past the flattening filter,the dose is measured and MLC can conform the beam.

Question 3

Of the following treatment units,which has the least amount of skin sparing?

A) orthovoltage
B) cobalt
C) 4 MV beam
D) 10 MV beam

Answer 3

A
Orthovoltage has the least amount of skin sparing.Depth of maximum dose is deposited on the skin surface.

Question 4

Installation of the first fully isocentric linear accelerator in the United States was in:

A) 1942
B) 1952
C) 1961
D) 1979

Question 5

Which of the following best describes the major components of a linear accelerator?

A) power supply,modulator,electron gun,accelerating waveguide,head,beryllium target
B) power supply,modulator,klystron,electron gun,"D"s,beryllium target
C) power supply,electron gun,accelerating waveguide,head,doughnut accelerator structure
D) modulator,klystron,electron gun,accelerator structure,waveguide,bending magnet

Question 6

Which of the following limited the use of orthovoltage x-ray machines for radiation therapy?

A) skin dose tolerance
B) proton contamination
C) excessive dose rate
D) neutron contamination
E) Nuclear Regulatory Commission requirement

Question 7

The half-life of a cobalt 60 source is:

A) 30 years
B) 1600 years
C) 5.26 years
D) 74.2 days

Question 8

Electron beams __________________.

A) require a flattening filter to make the electron beam profile symmetric and flat
B) require a scattering foil to make the electron beam profile symmetric and flat
C) interact with the transmission target before leaving the exit window
D) a,b,and c are true
E) b and c are true

Question 9

In treatments using kilovoltage equipment,filters are used to:

A) filter low-energy x-rays
B) shield the patient from all radiation exposure
C) collimate the beam
D) increase quantity

Question 10

When treating with electrons,the carousel rotates to place a _________________ in the beam to spread it out.

A) collimator
B) cone
C) scattering foil
D) flattening filter

Question 11

The rate of decay per month on a cobalt 60 unit is:

A) 1% per month
B) 2% per month
C) 3% per month
D) 5% per month

Question 12

A(n)_______________ test is performed on the cobalt 60 unit to determine whether the source's seal is broken.

A) penumbra
B) light field-radiation field coincidence
C) electron equilibrium
D) wipe

Question 13

The electron gun is similar to what part of an x-ray tube?

A) anode
B) rotating tungsten target
C) cathode
D) power supply

Question 14

Choose the most correct statement concerning Co-60 teletherapy.

A) A timer error factor must be added to the treatment time.
B) The head contains the source,shielding,and collimators.
C) The Co-60 source is 1 to 3 cm in diameter.
D) Co-60 emits two $\gamma$ -rays whose average energy is 1.25 MeV.
E) All of the above are true.

Question 15

The energy of a cobalt unit is:

A) 1.36 and 1.01 MeV
B) .662 and 1.5 MeV
C) 1.00 and 1.5 MeV
D) 1.17 and 1.33 MeV

Question 16

The circulator in a linear accelerator:

A) mixes the hot and cold water to get the right temperature
B) spins the electrons in the right direction
C) conducts microwaves from the RF driver into the klystron
D) isolates the klystron from reflected microwave power

Question 17

Orthovoltage x-ray machines have energies in the range of:

A) 1 kV to 100 kV
B) 150 kV to 500 kV
C) 200 MeV to 400 MeV
D) none of the above

Question 18

Choose the most accurate statement.

A) The penumbra from a Co-60 machine is smaller than that from a linear accelerator because the Co-60 source diameter is 3 mm.
B) The penumbra from a Co-60 machine is smaller than that from a linear accelerator because Co-60 has a source travel timer error.
C) The penumbra from a Co-60 machine is larger than that from a linear accelerator because Co-60 has a source travel timer error.
D) The penumbra from a Co-60 machine is larger than that from a linear accelerator because the Co-60 source diameter is 3 mm.

Question 19

Which of the following is not found inside the head of a linear accelerator?

A) ion chambers
B) target
C) accelerator structure
D) bending magnet
E) scattering foil

Question 20

Image-guided radiation therapy can be accomplished with: I.ultrasound units
II)CT scanner
III)kV imager
IV)cone beam
V)simulator

A) I,III,and IV
B) II,III,and V
C) I,II,III,and IV
D) III,IV,and V

Question 21

A Van de Graaff machine __________________. I.is an electrostatic generator
II)operates at 2 MV
III)operates a 200 kV
IV)uses a doughnut-shaped accelerator structure

A) I and II
B) II and IV
C) III and IV
D) I and IV

Question 22

A betatron produces megavoltage:

A) electrons
B) photons
C) protons
D) a and b

Question 23

Some of the more common medical accelerator hazards include: I.incorrect dose delivered
II)dose delivered to wrong area
III)machine collision
IV)emergency off malfunction

A) I,II,and IV
B) II,III,and IV
C) I,III,and IV
D) I,II,and III

Question 24

Inherent filtration is due to materials present in the x-ray tube itself that the beam must pass through.

Question 25

If a cobalt 60 source is stuck in the on position,you must retrieve the patient immediately and then push the source back in.

Question 26

Depth of maximum dose for a 15 MV machine is how far below the skin surface?

A) 0.5 cm
B) 1.5 cm
C) 2.5 cm
D) 3 cm

Question 27

Lipowitz metal is composed of:

A) tin bismuth,lead and cadmium
B) lead,tungsten,tin
C) tin,bismuth,tungsten,lead
D) bismuth,cadmium and lead

Question 28

What is the penumbra of a cobalt 60 machine with a source size of 3 cm,an SSD of 80 cm,and a source-to-diaphragm distance of 30?

A) 1 cm
B) 2 cm
C) 4 cm
D) 5 cm

Question 29

When using multileaf collimation,which concerns need to be evaluated?

A) penumbra between the leaves and the transmission of the leaves
B) movement of MLCs during the treatment give variation in dose that need to be evaluated along with penumbra between the leaves
C) movement of MLCs during treatment and interleaf transmission leakage
D) penumbra at the end of the leaves and interleaf transmission leakage

Question 30

Depth of maximum dose for a 10 MV machine is how far below the skin surface?

A) 0.5 cm
B) 1.5 cm
C) 2.5 cm
D) 5 cm

Question 31

Depth of maximum dose for a 6 MV machine is how far below the skin surface?

A) 0.5 cm
B) 1.5 cm
C) 2.5 cm
D) 5 cm