Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Radiation Therapy > Principles and Practice Review 1 > Flashcards

Principles and Practice Review 1 Flashcards

1
Q

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

A

accelerator structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

The backscatter factor is effected by all of the following EXCEPT:

  1. Treatment field size
  2. Radiation quality
  3. Quantity of radiation
A

Quantity of Radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

The tissue air ratio (TAR) at the depth of maximum electron buildup (Dmax) is:

  1. Always less than or equal to 1
  2. The backscatter factor
  3. Dependent on the field size
A

All of the above

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

The concept of tissue-air ratio (TAR) is most commonly employed for calculations involving:

A

SSD varying fields

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

The depth of maximum ionization is most dependent on

A

Beam energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

A 10MV linear accelerator is used at 100cm SSD. The location of maximum dose is found at a depth of

A

2.5cm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Percentage depth dose increases with increasing:

  1. Energy
  2. Depth
  3. Field Size
A

Energy and Field size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Tissue-air ratio decreases with decreasing

  1. SSD
  2. Depth
  3. Field size
A

Field size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

A wedge filter _____ the output of the beam and must thus be taken into account in the treatment calculations

A

decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

%DD increases with increasing

  1. energy
  2. depth
  3. field size
A

energy and field size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

TAR decreases with decreasing

  1. field size
  2. depth
  3. SSD
A

Field size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

When blocking is used in a treatment calculation, the area of the collimator is used in determining

  1. TMR
  2. Output Factor
  3. PDD
A

Output Factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Which of the following is not a tissue absorption factor?

A

Output factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Which of the following central axis depth dose quantities would most likely be used to compute an accurate MU setting on an 18MV unit for an isocentric treatment

A

TMR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Two parallel opposed equally weighed 6MV fields are separated by 20cm of tissue and treated with an SSD technique. The maximum dose will occur

A

1.5 under the skin surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

A wedge filter ______ the output of the treatment beam and must thus be taken into account in the treatment calculation

A

decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Mayneord’s factor is used to convert

A

PDD with a change in SSD from the standard

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

1Gy is the same as

A

100cGy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

The point of maximum electron equilibrium is referred to as

A

Dmax

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Dose rates:

A

Increase with increased field size and decrease with increased distance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

In a fixed SSD technique the dose is routinely normalized

A

at Dmax

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

In an isocentric treatment technique the most done is routinely normalized

A

at the isocenter

23
Q

What is the reference desert when delivering an external beam radiation therapy treatment using a 10MV SSD technique?

24
Q

What is the reference desert when delivering an external beam radiation therapy treatment using a 18MV SSD technique?

25
Calculate the equivalent square of a 13x12cm field blocked 12%
11.7
26
Calculate the equivalent square of a 13x9cm field blocked 7%
10.3
27
The gross tumor volume (GTV) ], as defined by the ICRU, mean:
The gross tumor volume (GTV) as defined by the ICRU name
28
The term clinical target volume (CTV), as defined by the ICRU, means
A tissue volume that contains demonstrable GTV a defend volume
29
The field size when using an SSD technique and a photon mean usually defined
on the skin surface
30
The angle of beam divergence is
larger farther from the CAX
31
The three planes in a patient are across the body, along the body in a lateral view, and along the body in an anterior view. Respectively they are referred to as
axial, sagittal, and coronal
32
When the treatment field is designed by the radiation oncologist, margins are always added around a tumor because of
uncertainties in determining tumor extent, penumbra of the be a, and patient motion
33
the isocenter is
the point around which the source of the beam rotates
34
What is the percent depth dose of a 12x7cm field delivering a 10 MV x-ray at a depth of 2.5cm?
100.0
35
What is the percent depth dose of a 12x7cm field delivering a 18MV x-ray at a depth of 2.5cm?
97.3
36
What is TAR of a 10x16cm field blocked 5% delivering a 10 MV x-ray at a depth of 10.0cm
.866
37
The depth of maximum ionization is most dependent upon
beam quality
38
TAR is dependent upon: 1. Energy 2. SSD 3. Depth 4. Field Size
Energy Depth Field Size
39
When using shielding blocks what is effected?
Equivalent square field (ESF)
40
The intensity of a high energy photon beam at any given distance from a source is:
inversely proportional to the square of the distance
41
Dose rate for a linear accelerator is expressed at
cGy?MU
42
TAR is advantageous because
ratios do not depend on source to skin distance
43
Mayneord factor compensates for a change in central axis depth dose and includes corrections for
inverse square law
44
Which beam would produce the maximum amount of backscatter
the one with least energy usually 1.25MV
45
As beam quality increases, maximum dose____.
increases
46
The %DD for a 12x12cm field, 4MV photon beam, 5cm depth, and 80cm SSD is 82.8. Calculate the %DD for the same field size and depth for 100cm SSD.
84.3
47
If the field size indicator is set for 20x20cm at 80cm SSD, what is the field size at 84cm?
21x21cm
48
If a Co-60 unit is used at 80cm SSD for a 15x15cm field size and has a %DD of 58.4 at 10cm depth, what is the %DD for the same field size and depth at 100cm SSD?
60.9
49
The Dmax for a 10MV photon beam at an 100cm SSD with a 15x15cm field is approximately
2.5cm
50
Mayneord's F-factor is of use when there is a change in
SSD
51
Calculate the equivalent square for a 10x15cm rectangular field
12x12cm
52
Determine the equivalent square for a rectangular field with a width of 8cm and a length of 15cm
10.4cm
53
Determine the equivalent square for a rectangular field with a width of 7cm and a length of 17cm
9.9cm
54
The counterpart of the timer setting of a Co-60 unit is most similar to the ______of a LINAC.
monitor unit

Radiation Therapy (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions