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part 3: treatment dose and prescription > A.prescription > Flashcards

A.prescription Flashcards

1
Q

The total dose must be included on the

A

prescription

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2
Q

on the treatment prescription it must include

A
  • fractionation schedule
  • treatment technique
  • beam energy
  • imaging
  • gating
    and bolus
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3
Q

some things that aren’t on the prescription are

A
  • MU
  • doses to critical structuser
  • DVH - dose volume histogram
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4
Q

_____ change depending on the location of the tumor, treatment intent, and the organs at risk surrounding the tumor

A

Total doses

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5
Q

An example of a typical palliative dose is a daily fraction of

A

300 cGy for 10 fractions and a total dose of 3,000 cGy

  • 5 fractions/week
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6
Q

Total doses range from approximately ____ for curative treatments

A

50 - 80 Gy (5000 - 8000 cGy)

  • 180-200 cGy
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7
Q

To ensure tumor control there are recommended doses to be delivered: For subclinical disease doses of

A

45 - 50 Gy is recommended

-Subclinical diseases are conditions where the disease is identifiable with laboratory testing or imaging, but have no outward signs or symptoms

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8
Q

The number of fractions and dose per fraction must be

A

included on the prescription

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9
Q

____breaks up the total dose into multiple smaller doses so that cells can repair

A

Fractionation

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10
Q

The total amount of fractions varies with the

A

total tumor dose

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11
Q

___fractionation: Daily fractions of 180 - 200 cGy, five days per week for multiple weeks

A

Conventional

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12
Q

_______fractionation: Larger dose per fraction with less fractions than conventional fractionation schedules, but same overall dose

A

Accelerated / hypofractionation

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13
Q

____: Smaller dose per fraction and more fractions than conventional fractionation schedules

A

Hyperfractionation

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14
Q

Hyperfractionation is recommended for

A

slower growing tumors

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15
Q

Hypofractionation is recommended for

A

faster growing tumors

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16
Q

BID means ______

A

twice daily with 6 hours in between

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17
Q

Beam energy should be displayed on

A

the prescription

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18
Q

The _____ used for treatments and is chosen depending on the thickness of the patient and the depth of the tumor

A

beam energy

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19
Q

Tumors in areas of the body that are thicker use ____beam energies

A

higher

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20
Q

most treatments for pelvic tumors use

A

15X

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21
Q

most treatments for brain tumors use

A

6X

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22
Q

When beam energy is increased, skin sparing is increased for

A

photon beams

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23
Q

Different beam energies have different depths for

A

dmax

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24
Q

_____particles: Two protons and two neutrons (also known as a helium nuclei) released from an unstable heavy nucleus as it decays

A

Alpha

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25
Q

Alpha particles has a charge, heavy mass and ___LET

A

high

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26
Q

____particles: Electrons that are released by a nucleus

A

Beta

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27
Q

Beta particles are __ charges

A

Negatively charged (negatron) or positively charged (positron)

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28
Q

____: Electromagnetic radiation, known as photons

A

X-rays

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29
Q

X-rays have no

A

mass or charge

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30
Q

X-rays interaction occurs near the

A

nucleus

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31
Q

_____: Photons naturally emitted from a nucleus

A

Gamma rays

32
Q

Natural background radiation include:

A

Cosmic rays, terrestrial radiation, and radionuclides in the human body

33
Q

tumor volume that is visible and can be palpated

A

GTV- gross tumor volume

34
Q

_______= GTV and the area around it that may have microscopic disease

A

CTV- clinical target volume

35
Q

_____= CTV plus motion of the tumor caused by breathing or involuntary motions

A

ITV- internal target volume

36
Q

____ are required to determine the ITV

A

4D CT simulation scans

37
Q

______= CTV and an area around it to give a margin for uncertainties

A

PTV- planning target volume

38
Q

_____ is the volume of tissues that is given a large portion of the dose

A

Irradiated volume

39
Q

_____ are organs close to the irradiated area that may affect or limit the dosage delivered

A

Organs at risk (OAR)

40
Q

_______ are established based on tolerence doses of the organs at risk and the dose distributions

A

Treatment fields

41
Q

Multiple treatment fields are more commonly used for

A

curative treatment

42
Q

Single fields are more cornmeniy used for

A

palliative treatments

43
Q

____ is arranged depending on the orientation and organs at risk near the tumor

A

Field orientation

44
Q

MLCs and other beam modifiers can be used to

A

further shape the beam

45
Q

_____dose distributions usually require multiple field

A

Adequate

46
Q

_____ fields are usually used for a posterior spine field

A

Single

47
Q

_____have a hinge angle of 180 degrees

A

Parallel opposed portals (POP)

48
Q

Hinge angle refers to the degrees between each

A

gantry angle

49
Q

____ technique is commonly used for structures within the abdomen, such as the pancreas, bladder, rectum, etc.

A

Three-field

50
Q

When an odd number of fields are used, it is common for ____to be used to even out dose distribution

A

wedges

51
Q

________ is commonly used for deep tumors within the pelvis or abdomen

A

Four-field technique/four-field box

52
Q

4-field box fields have a hinge angle of

A

90 degrees

53
Q

______ technique has a hinge angle that is less than 180 degrees between two fields

A

Wedge-pair

  • used for small superficial tumors
54
Q

Wedge-pair- requires wedges to have a more even

A

dose distribution

55
Q

The thick ends of the wedges, also known as the _____ face each other

A

heel,

56
Q

_______ are also known as “arc therapy,” where the radiation is delivered while the gantry is moving in an arc from one set point to another

A

Rotational fields

57
Q

For partial arcs, or arcs less than 360 degrees, the treatment planning method is called

A

past pointing

58
Q

For arcs that are ____ degrees, the beam is set to treat at the exact depth of the center of the tumor

A

360

59
Q

Arc speed is calculated as

A

degree/MU

60
Q

Before treating with an arc, the therapist should do a dry run of the gantry rotation to ensure there will be

A

no collisions between the gantry and the patient or table

61
Q

For ____fields, the gantry does not move while the radiation beam is delivered

A

fixed

62
Q

different ____ can deliver different percentages of the total dose

A

fields

63
Q

AP:PA weighted is ___ proportionally

A

2:1

64
Q

AP field will deliver 2/3 of the dose which means to multiply the total prescription dose by __________ to find the amount of cGy delivered in the AP field

A

2/3

65
Q

The isocenter is located at __Cm

A

100

66
Q

Max field size = ____ cm at 100 SSD

A

40 x 40

67
Q

Photon therapy energies range from about

A

4 to 35 MV

68
Q

Electron therapy energies range from about

A

4 to 22 MeV

69
Q

Treatment table can hold up to

A

350 pounds

70
Q

Any changes in the plan must be ____prior to the patient’s next treatment

A

recognized

71
Q

If the changes to treatment plan include the field size or shape, the new field must be

A

imaged for confirmation

72
Q

Changes in fractionation or dose must be properly documented and followed as

A

prescribed

73
Q

Beam ______ will be placed in between the beam and the patient

A

modifiers

74
Q

Beam Modifers attenuate some of the primary beam and require an increase in monitor units to compensate for the

A

partial loss of useful beam

75
Q

What treatment modifier need to be on prescription

A

bolus

76
Q

What treatment modifier does not need to be on prescription

A

MLC shape, blocks, wedges

part 3: treatment dose and prescription (3 decks)

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