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Radiation Therapy > First Long Examination > Flashcards

First Long Examination Flashcards

1
Q

Defined as the quantity of radioactive substance that gives rise to a decay rate of 1 decay per second.

A

Becquerel (Bq)

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2
Q

Traditional unit of radioactivity; It is the amount of radioactive substance which gives rise to a decay rate of 3.7 x 1010 decays per second.

A

Curie (Ci)

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3
Q

Expresses how much ionization the beam causes in the air through which it travels; It is the quantity of X-rays or gamma-rays such that the associated electrons emitted per kilogram of air at S.T.P produce ions carrying 1 coulomb of electric charge.

A

Radiation Exposure

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4
Q

What is the SI unit for radiation exposure?

A

C/kg

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5
Q

What is the traditional unit for radiation exposure?

A

Roentgen

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6
Q

Defined as the quantity of X- or gamma rays such that the associated electrons emitted per kilogram of air at S.T.P produce ions carrying 2.58 x 10-4 coulombs of electric charge.

A

Roentgen

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7
Q

Energy deposited in the absorber when radiation interacts with it.

A

Absorbed Dose (D)

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8
Q

What is the SI unit for absorbed dose?

A

Gy

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9
Q

What is the traditional unit for absorbed dose?

A

rad

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10
Q

Defined as the absorption of 1 joule of radiation energy per kilogram of material.

A

Gray

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11
Q

Defined as the absorption of 10-2 joules of radiation energy per kilogram of material.

A

rad

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12
Q

Based on estimates of the ionization capability of the different types of radiation

A

Equivalent Dose (H)

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13
Q

What is the formula for equivalent dose and what factors are considered?

A

H = WrD

where Wr is the radiation weighting factors and D is the absorbed dose

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14
Q

Includes radiation weighting factors as well as estimates of the sensitivity of different tissues.

A

Effective Dose (E)

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15
Q

What is the formula for effective dose and what factors are considered?

A

E = ΣWtH

where Wt is the tissue weighting factors and H is the equivalent dose

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16
Q

Derived unit of ionizing radiation dose in the International System of Units (SI) and is a measure of the health effect of low levels of ionizing radiation on the human body.

A

Sievert

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17
Q

Expresses the exposure rate produced by the gamma-rays emitted from a radioisotope; It is defined as the exposure rate per unit activity at a certain distance from a source.

A

Specific Gamma Ray Constant

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18
Q

What is the SI unit for specific gamma ray constant?

A

C/kg/s/Bq at 1 m

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19
Q

What is the traditional unit for specific gamma ray constant?

A

R/hr/mCi at 1 cm

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20
Q

Law on the influence of distance on the intensity of radiation beam; It states that radiation intensity will decrease with the square of the distance from the source

A

Inverse Square Law

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21
Q

A very destructive process which occurs in some heavy nuclei which split into 2 or 3 fragments plus some neutrons

A

Spontaneous Fission

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22
Q

Which phase of the cell cycle is radioresistant?

A

S phase

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23
Q

Which phase of the cell cycle is radiosensitive?

A

G2 and M phases

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24
Q

Type of radiation damage wherein photons physically break one or both of the sugar phosphate backbones or break the base pairs of the DNA.

A

Direct Action or Damage

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25
Q

Photons are absorbed in the water of an organism causing excitation and ionization in the water molecules

A

Indirect Action or Damage

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26
Q

Type of break in the sugar phosphate backbone wherein only one of the sugar phosphate backbones is broken; It is readily repaired using the opposite strand as a template; Base pair substitutions and frameshift mutations can still occur

A

Single Strand Break

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27
Q

Most detrimental lesions in chromosomes; Difficult to repair, they can cause mutations and cell death

A

Double Strand Breaks

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28
Q

What is the process of DNA repair?

A

Excision

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29
Q

Enzyme that recognizes damaged DNA

A

Glycosylase

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30
Q

Enzyme that cuts out damaged DNA

A

Endonuclease

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31
Q

Enzyme that resynthesizes the original DNA

A

DNA Polymerase

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32
Q

Enzyme that repairs the sugar phosphate backbone

A

DNA Ligase

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33
Q

Sequence of Radiation Injury

A

1) Exposure
2) Latent Period
3) Period of Injury
4) Recovery Period

34
Q

Factors Affecting Biologic Response to Radiation

A

1) Tissue Radiosensitivity
2) Dose
3) Duration of Exposure
4) Age of the Patient

35
Q

Types of Radiation Effects

A

1) Acute and Late Effects
2) Somatic and Genetic Effects
3) Deterministic and Stochastic Effects

36
Q

Type of effect wherein the probability of occurrence increases with increasing dose but the severity does not depend on the dose.

A

Stochastic Effects

37
Q

Type of effect wherein there is a threshold dose, below which the effect does not occur. However, once the threshold is reached, the severity of an effect increases with dose.

A

Deterministic Effects

38
Q

Irradiation of the entire body by a high dose of ionizing radiation in a very short period of time.

A

Acute Radiation Syndrome (ARS)

39
Q

What is the major cause of ARS?

A

Depletion of parenchymal stem cells

40
Q

What are the stages of ARS?

A

1) Prodromal Stage
2) Latent Stage
3) Manifest Illness Stage
4) Recovery or Death

41
Q

Types of Radiotherapy According to Aim

A

1) Curative
2) Palliative
3) Prophylactic
4) Total Body Irradiation

42
Q

Type of radiotherapy that prevents possible metastases or recurrences

A

Prophylactic

43
Q

Type of radiotherapy that involves ablation of bone marrow in order to suppress the immune system

A

Total Body Irradiation

44
Q

Types of Radiotherapy According to Timing

A

1) Adjuvant Radiotherapy
2) Neoadjuvant Radiotherapy
3) Radiochemotherapy

45
Q

Radiotherapy given after any kind of treatment modality

A

Adjuvant Radiotherapy

46
Q

Radiotherapy given before any kind of treatment modality

A

Neoadjuvant Radiotherapy

47
Q

Radiotherapy given concurrently with chemotherapy

A

Radiochemotherapy

48
Q

Types of Radiotherapy According to Mode

A

1) External Beam Radiation Therapy

2) Internal Beam Radiation Therapy

49
Q

Type of radiotherapy wherein the radioactive material is placed in the body near the cancer cells

A

Internal Beam Radiation Therapy

50
Q

Sealed source of radiotherapy

A

Brachytherapy

51
Q

Unsealed source of radiotherapy; Delivered through ingestion or intravenous route

A

Systemic Radioisotope Therapy

52
Q

Type of radiotherapy wherein radiation is delivered by a machine outside of the body

A

External Beam Radiation Therapy

53
Q

Delivers radiation beams from different directions designed to match the shape of the tumor through the use of 3D anatomical data from CT or MRI; Aim is to apply the maximum dose to the target; Helps to reduce radiation damage to normal tissues.

A

Three-Dimensional Conformal Radiation Therapy (3D-CRT)

54
Q

Form of 3D-CRT where imaging (eg CT scan) are done before each treatment; This allows the radiation oncologist to adjust the position of the patient or refocus radiation as needed to hit the tumor; Accounts for target volume changes during RT such as tumor volume decrease or weight loss.

A

Image-Guided Conformal Radiation Therapy (IGRT)

55
Q

Similar to 3D-CRT but changes the strength of some of the beams in certain areas, therefore, certain parts of the tumor have higher doses and help lessen damage to nearby normal body tissues.

A

Intensity Modulated Radiation Therapy (IMRT)

56
Q

Form of IMRT that delivers radiation inside a large “donut”; Delivers many small beams of radiation at the tumor from different angles around the body

A

Helical-tomotherapy

57
Q

Administer large dose of radiation to a small tumor area and is very precisely aimed; Used for brain tumors and other tumors inside the head; Brain imaging are done to determine exact location of the tumor and radiation is sent to the area from many different angles; Given in more than five fractions

A

Stereotactic Radiotherapy (SRT)

58
Q

Administer large dose of radiation to a small tumor area and is very precisely aimed; Used for brain tumors and other tumors inside the head; Brain imaging are done to determine exact location of the tumor and radiation is sent to the area from many different angles; Given in one to five fractions in ablative doses

A

Stereotactic Radiosurgery (SRS)

59
Q

Administer large dose of radiation to a small tumor area and is very precisely aimed; Used for treatment outside the brain

A

Stereotactic Body Radiation Therapy (SBRT)

60
Q

Given directly to the tumor during surgery; Used when tumors cannot be removed completely or risk of cancer recurrence is high; Can give large dose of radiation which limits effects on nearby tissues

A

Intraoperative Radiation Therapy (IORT)

61
Q

Radioisotopes used for brachytherapy

A

1) Ir-192
2) I-125
3) Pd-103

62
Q

What type of decay does cobalt-60 undergo?

A

Beta- decay

63
Q

What energy is emitted by the decay of cobalt-60?

A

Two gamma emissions

64
Q

What is the half life of cobalt-60?

A

5.27 years

65
Q

What collimator is often used for EBRT?

A

Multileaf Collimator

66
Q

What are the 5 R’s of Fractionation?

A

1) Repopulation
2) Repair
3) Redistribution
4) Reoxygenation
5) Radiosensitivity

67
Q

What are the three types of cell damage caused by ionizing radiation?

A

1) Lethal Damage
2) Sublethal Damage
3) Potentially Lethal Damage

68
Q

Gross palpable or visible/demonstrable extent and location of malignant growth

A

Gross Tumor Volume

69
Q

Tissue volume that contains demonstrable GTV and/or subclinical microscopic malignant disease, which has to be eliminated; May contain microscopic disease and other areas considered to be at risk and requiring treatment (eg positive lymph nodes)

A

Clinical Tumor Volume

70
Q

Consists of the CTV plus an internal margin; Designed to take into account variations in the size and position of the CTV relative to the patient’s frame (e.g. breathing)

A

Internal Tumor Volume

71
Q

Geometrical concept defined to select appropriate beam arrangements, taking into consideration the net effect of all geometrical variations, in order to ensure that the prescribed dose is actually absorbed in the CTV

A

Planning Target Volume

72
Q

Type of photon beam wherein there is a higher dose near the entrance at the depth of dose maximum.

A

Single Photon Beams

73
Q

Requires adjusting the patient such that the skin is at the correct distance from each beam orientation

A

Fixed SSD Technique

74
Q

Requires placing the patient such that the target is usually at the isocenter

A

Isocentric Techniques

75
Q

This beam combination is well suited to a large variety of treatment sites (eg. lung, brain, head and neck)

A

Parallel Opposed Beams

76
Q

Allow for a higher dose in the beam intersection region;

A

Multiple Coplanar Beams

77
Q

Isodose curves for two bilateral arcs of 120° each; Produce a relatively concentrated region of high dose near the isocenter but they also irradiate a greater amount of normal tissue to lower doses than fixed-field techniques

A

Rotational Technique

78
Q

Most often used for treatments of brain as well as head and neck; Useful to get more adequate critical structure sparing compared to conventional coplanar

A

Multiple Non-coplanar Beams

79
Q

Used to evaluate treatment plans along a single plane or over several planes in the patient

A

Isodose Curves

80
Q

Most commonly used as a plan evaluation tool and to compare doses from different plans or to structures

A

Dose-Volume Histogram

Radiation Therapy (1 decks)

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