Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Laura Nappi online course > Beam Energy > Flashcards

Beam Energy Flashcards

(59 cards)

Start Studying
1
Q

T/F: you CAN find beam energy on the treatment prescription/plan

A

TRUE

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

beam energy choice depends on what factors? (3)

A
  1. thickness of patient
  2. depth of tumor
  3. if skin sparing is desired
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

generally for patient separation/thickness LESS than 22 cm, what beam energy is used?

A

4-6 MV

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

generally for patient separation/thickness MORE than 22 cm, what beam energy is used?

A

10-18 MV

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

as beam energy increases, what happens to DMAX?

A

DMAX also increases

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

what is dmax for a 4MV beam?

A

1 cm

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

what is dmax for a 6MV beam?

A

1.5 cm

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

what is dmax for a 10MV beam?

A

2.5 cm

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

what is dmax for a 15MV beam?

A

3.0 cm

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

what is dmax for a 20MV beam?

A

3.5 cm

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

what is dmax for a 25MV beam?

A

5 cm

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

what is dmax for a 6MeV beam?

A

1.5 cm

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

what is dmax for a 9MeV beam?

A

2.2 cm

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

what is dmax for a 12MeV beam?

A

2.8 cm

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

______ = point at which 100% of dose is distributed within patient

A

dmax

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

as beam energy increases, so does dmax - what happens to the skin sparing?

A

increases as well

–dmax increases, so does beam energy, and skin sparing –> cause penetrates further into body and not as close to skin surface

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

what is the green region on this photon PDD and depth graph?

A

build up region

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

what is NOT spared when using electron?

A

the skin is NOT spared

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

what is the green region on this drawn diagram of a patient getting a photon trt?

A

build up region

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

which curve is representing electrons and which curve is representing photons?
PINK VS BLUE

A

pink = photons MV
blue = electrons MeV

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

once an ___MeV/MV___ beam hits skin surface, it will begin to build up until it hits dmax releasing 100% dose there

A

MV (photon)

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

what type of beams are very superficial?

electrons or photons

A

electrons

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

nearly ___% of electron beam is delivered at skin surface

A

100%

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

for photon beams, ___-___% of dose is delivered to skin surface and then 100% at dmax

**this can change/depends on beam energy selected

25
which beam energy participates in skin sparing effect?
PHOTON (MV)
26
once an electron hits dmax, what happens?
they abruptly fall to zero; zero % --this is how other tissues are spared during e- treatments, unlike photons
27
unlike photons, electrons start off high meaning they do not need a _______ region
build up region --there is no build up region for electrons
28
which curve correlates to electrons, and which for photons?
PINK = photons (MV) BLUE = electrons (MeV)
29
which isodose curve belongs to electrons... and which for photons?
A. deeper curves- PHOTON B. shallow curves - ELECTRONS
30
higher beam energies yield ___greater/lesser___ PDDs
GREATER
31
higher energies have ___smaller/larger___ gaps between skin surface and dmax
larger
32
which isodose curve is a higher energy photon beam, and which belongs to a lower energy photon beam?
A. lower energy isodose curve B. higher energy isodose curve **we know by looking at dmax and gaps between skin surface and dmax
33
concept check: For whole brain treatments we use lower energy beams, what would happen is we used higher energies?
we'd miss tissue right next to skull, as beam would penetrate straight on through
34
T/F: there IS a shape difference between electron and photon isodose curves
true
35
which isodose curve is a rough sketch of a photon curve and which is an electron?
A. electrons B. photons
36
on electron isodose curves ... higher energy lines ______ laterally
constrict laterally
37
low energy electron isodose curve lines are ___closer/farther___ - whereas high energy e- isodose curve lines are __closer/farther__
low energy lines ---> closer high energy lines --> farther **safe to assume same for high/low energy photons beams
38
what is Bowing Effect on electron isodose curves?
when low energy isodose lines expand laterally --Bowing Effect is due to beam scatter! --> e- scatter easy
39
what causes Bowing Effect for electron isodose curves?
beam scatter
40
Photon or Electron isodose curves -- penetrate in a more forward direction
PHOTONS
41
Photon or Electron isodose curves -- are very superficial
ELECTRONS
42
Photon or Electron isodose curves -- have greater energies available at greater depths
PHOTONS
43
CA = _____ ______
Central Axis
44
what is equation to find 80% central axis depth dose of electrons?
E/3
45
what is equation to find 90% central axis depth dose of electrons?
E/4
46
what/where is Therapeutic Range of electrons?
90%
47
___-___% isodose lines of electrons are most useful because after them, the dose falls off/electrons lose energy at a high rate
80-90%
48
electrons lose ___ MeV per cm in water or soft tissue
2 MeV/cm
49
once dmax is hit for electrons where does any dose after that come from?
mainly from contamination, not the primary beam
50
what does "dose fall off" mean?
losing energy at a high rate
51
________ are heavier, charged particles that scatter at smaller angles
protons
52
protons compared to electrons, which have a larger scatter angle?
electrons
53
protons, compared to electrons and photons, are slowed by __lower/higher___ Z materials
lower
54
what is another name for proton dmax?
bragg peak
55
a proton bragg peak is typically too narrow to cover a whole tumor/ enough tumor volume - SO what happens
SOBP ; several beams of different energies are used to spread out the Bragg Peak
56
what does SOBP stand for?
Spread Out Bragg Peak
57
protons: a _______ ensures that the most superficial/proximal, to the most distal/deepest part of tumor is covered
SOBP - Spread out bragg peak
58
an SOBP creates what
a flatter, longer line we can use to treat larger areas w/ protons
59
the following is an example of what? A = B =
A --> Bragg Peak B --> SOBP - spread out bragg peak

Laura Nappi online course (54 decks)

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