Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Dosimetry > Finals Material > Flashcards

Finals Material Flashcards

1
Q

What do the initials in the following acronyms stands for:

GTV, CTV, PTV

A

GTV: gross tumors volume
CTV: clinical target volume
PTV: plan target volume

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

Which term/acronym is the volume which accounts for organ movement and setup uncertainties

A

PTV

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

This type of technique gives the shape of a diamond

A

“crossfire” technique which is 2Ap obliques and 2 PA obliques

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

2 EQUALLY weighted parallel opposed AP-PA fields will give a shape of :

A

An hour glass

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

AP-PA and a right and left laterals are nicknamed what

A

4 field “box” or “brick”

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

Prior to the availability of IMRT- a technique using AP,RPO, LPO fields were frequently used to treat what area

A

Cervical esophagus

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

A 3 field recital cease use PA and right and left laterals with wedges. The wedges should be placed with the ______ towards the posterior of the patient’s anatomy

A

Heel towards the posterior of the patient anatomy

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

A wedge technique may be used on breast tangents. To compensate for the slope of the breast, where would the heel of the wedge be placed

A

Towards the nipple

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

Name the technique which was used for ovarian cancer- total abdomen, pelvis, and sub diaphragmatic lymph nodes

A

Moving strip technique

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

Next the 2 factors which affect the Roentgen to cGy conversion factor

A

Density of the irradiated material (Z)

Energy of the beam

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

Lines that connect points of equal dose are called

A

Isodose curves

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

Name any 2 factors which affect the shape of the isodose chart

A

Field size

Beam energy

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

The point which is labeled 100% on an isodose chart is called

A

Normalization point

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

The point labeled 100% for a treatment which uses MORE THAN ONE BEAM (FIELD) is generally placed where

A

At the isocenter

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

What is the most accurate method to measure a radiation beam and create an isodose chart

A

Ionization chamber

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

The rapid fall off of dose at the edge of the beam is called

A

Penumbra

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

Formula for TAR

A

TAR= TAR0 + SAR

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

When doing the clarkson calculation on a blocked field, which part of the TAR value is being “adjusted”

A

(Sc) for the lack of scatter

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

TARo denotes the tissue air ratio value for field 0x0. This field size indicates the field from the portion of the beam created when the electrons hit the target. This is called the _____ beam

A

Primary

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

The blocked equivalent square can also be called

A

Effective field size

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

Write the 3 metals which makes up the Thoreaus filter in order from the tube to the patient

A

Tin (Sn), Cooper (Cu), Aluminum (Al).

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

Tissue air ratio (TAR) at Dmax is also known as

A

Back scatter factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

TAR is NOT dependent on

A

SSD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

When using either TAR or TMR for monitor unit calculations, the field size and machine output are measured at what distance

A

100 cm- SAD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

The ratio of dose at depth compared to the dose at Dmax when bOTH measurements are take at the same distance from the radiation is defined as

A

TMR- tissue maximum ration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Cherry end is a lead alloy and consists of what 4 metals

A

Lead, tin, bismuth, and cadiminum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

In order to ensure adequate shielding of normal tissue s, the thickness of a block or MLC must be at least how many HVL thick

A

5 HVL thick

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

If the treatment is given through a “hole”, in the block, like an electron cutout, this type of block is called

A

A negative block

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

If the Gantry rotates 360 while the radiation beam in on, this type of treatment is called

A

Rotational therapy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Name the radiation field which treats the lymph nodes ABOVE the diaphragm

A

Mantle field

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

How many centimeters of cerobend are needed to have the Same shielding ability as 1cm of pure lead

A

1.25

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Name the machine which uses Thoreaus filter

A

Orthovoltage machine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

PDD compares the dose at some depth to the dose at ___

A

Dmax

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Sc and Sp correct for the change in scatter when the field size is different than the reference field size. What is the reference field size?

A

10x10

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Sc is _____ than 1 when the treatment field size is larger than the reference field size

A

Greater than

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Sp is ____ than 1 when the treatment field size is smaller than the reference field size

A

Lesser than

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

When using PDD to calculate the correct number of MU to deliver the prescribe tumor dose, the machine output (aka reference dose rate) used must be know at what distance from the radiation source?

A

Treatments SSD and Dmax depth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Field size will ____ as PDD increase

A

FS increase as PDD increase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

PDD ____ as you go deeper into the patient

A

Decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

When using PDD to calculate the correct number of MU to deliver a prescribe dose, where is the field size measured

A

On the skin surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

The PDD value at Dmax for any field size ,beam energy, or SSD is equal to

A

100% or 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

As beam energy increases, what happens to PDD

A

Energy increase, PDD increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

As field size increase, what happens to PDD

A

FS increase, PDD increase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

As SSD increase, what happens to PDD

A

SSD increase,PDD increase

45
Q

As you go deeper into the patient, what happens to PDD

A

Deeper, PDD decrease

46
Q

Mayneord factor is an application of which law

A

Inverse square law

47
Q

When would you use sterling formula (aka equivalent square)

A

When the treatment fields are not square field size. So this is an estimate of a rectangle to a square

48
Q

If the SSD decreases, how would this affect the back scatter factor

A

SSD does NOT affect BSF

49
Q

List in order from the MOST to the LEAST penetrating beam machine

(Gorillas Can Swing Over Short Mountains)

A 
Megavoltage - MOST 
Supervoltage 
Orthovoltage 
Superficial 
Contact 
Grenz Ray
50
Q

Which machine type uses 10-15kVp beam

A

Grenz Ray

51
Q

Which machine toe measured its HVL in millimeters of Copper

A

Orthovoltage

52
Q

Which machine type uses beam energy greater than or equal to 1000kVp

A

Megavoltage

53
Q

This is the intersection point of the Collimator axis and the gantry axis of rotation

A

Isocenter

54
Q

Unit of exposure in air

A

Roentgen (R)

55
Q

This distance between the patient skin and the depth of max ionization (Dmax) is called

A

The build up region

56
Q

Tissue equivalent material is called Bolus. Examples includes

A

Wax
Superfluous
Water

57
Q

The most frequently used beam modifying device is

A

Wedges

58
Q

The standard range of wedge angle is from ___ to ____

A

15 degrees to 60 degrees

59
Q

When the upper Collimator moves during the treatment and gives a “wedge effect”. This type of wedge is called

A

EDW- enhance dynamic wedge

60
Q

Name the type of wedge which is generally used on a Cobalt 60, where it’s toe is aligned at the field edge and there is a separate wedge for each field width

A

Individual wedge

61
Q

In order to Make up for the lack of tissue and maintain skin sparring, what can be used to account for a sloping skin surface

A

Compensators or wedges

62
Q

The area where there is a lack of tissue is called

A

Air gap

63
Q

Identify the factor which adjusts the PDD when the treatment SSD is different than the SSD used to measure PDD table

A

The Mayneord Factor (F)

64
Q

” f “ factor is the roentgen to cGy conversion factor and is affected by

A

Density of irradiated material

Beam energy

65
Q

How do you calculate dose using “ f” factor

A

(Exposure R)(f of the material)

66
Q

Point where maximum absorb dose occurs for a single photon field

A

Dmax

67
Q

What is the Dmax for cobalt 60

A

0.5cm

68
Q

What is the Dmax for 6MV

A

1.5cm

69
Q

What is the Dmax for 10Mv

A

2.5cm

70
Q

What is the Dmax for 18Mv

A

3.5cm

71
Q

Dmax is affected primarily by

A

Beam energy

72
Q

Dmax occurs at the _____ for low energy

A

At the skin surface

73
Q

Dmax occurs _____ for high energy

A

Beneath the skin surface

74
Q

The distance between the patient skin surface and Dmax

A

Build up region

75
Q

Blade pairs capable of independent movement

A

Asymmetrical jaws

76
Q

PDD field size is measured on the

A

Skin

77
Q

The amount of radiation coming from the machine at a specific distance

A

Reference dose rate

78
Q

(Roentgen)x(BSF)x(“f” factor) is the machine output for

A

Low energy machines like orthovoltage

79
Q

Amount of radiation scattered “back”, adding to the skin dose

A

Back scatter factor

80
Q

For energies with HVL greater than 1mmCu, BSF

A

Decreases due to more forward scatter

81
Q

Increase in FS cause an ______ in BSF

A

Increase FS cause increase n BSF due to more tissue being covered

82
Q

The Mayneord factor is used when

A

There is a change in SSD

83
Q

As FS increase, TAR

A

Increase

84
Q

As energy increase, TAR

A

Increase

85
Q

As you go deeper into the patient, TAR

A

Decrease due to moving further away from the source

86
Q

As SSD increase, TAR

A

Is not affected. SSD does it change TAR

87
Q

Blocks must be at least _____ thick to allow for less than 5% transmission

A

5HVL

88
Q

Cerrobend is made of

Bacon, lettuce, tomato with cheese

A

Bismuth
Lead
Tin
Cadmium

89
Q

Main advantage of cerobend

A

Low melting point

90
Q

Divergent blocks have ____ edges

A

Slanted edges

91
Q

Non divergent blocks have ___ edges

A

Non slanted edges

92
Q

Positive block treats ____

A

Around.

93
Q

Negative blocks treats _____

A

Through the hole

94
Q

This technique is used to treat BELOW the diaphragm

A

Inverted Y

95
Q

Clarkson calculation is also called

A

Irregular field calculation

96
Q

Clarkson calculation is done for

A

Calculation to correct for the lack of scatter due to blocking

97
Q

Isodose curves is measured by

A

Radiographic films
Solid sta detectors (TLD )
Ion chamber (most reliable)

98
Q

Factors affecting isodose charts

A

Energy
FS
SSD
Source size

99
Q

For a single field, the normalization point is placed at

A

Dmax

100
Q

For multiple fields, the normalization point is placed at

A

The isocenter

101
Q

Isodose shift methods is used for

A

Sloping skin surface

102
Q

MLC and cerobend modify the ____ of the beam

A

Shape of the beam

103
Q

Wedges modify the ____ of the beam

A

Shape of the beam and changes the whole isodose chart

104
Q

Angle through which an isodose curve is tilted at the central Ray of the beam

A

Wedge angle

90- (.5hinge)

105
Q

Angle between the central Ray of 2 beams

A

Hinge

180- (2 x wedge)

106
Q

Type of wedge that accommodates all field size

A

Universal wedge

107
Q

Contours are measurements of the patient both ____ and ____

A

Internally and externally

108
Q

The most accurate method of obtaining a patient contour

A

CT Scan

Dosimetry (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions