56. RADIOTHERAPY: THE 4 R'S OF FRACTIONATION Flashcards

1
Q
  1. What are the 4 R’s of Fractionation?
A
  1. Repair
  2. Redistribution
  3. Re-Oxygenation
  4. Repopulation
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2
Q
  1. What is Repair?
A
  • this happens every few hours
  • the cells are allowed to repair sub-lethal damage
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3
Q
  1. What is Redistribution?
A
  • this happens every few hours to days
  • the cell is given time to move to a more radiation
    sensitive phase of the cell cycle
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4
Q
  1. What is Re-Oxygenation?
A
  • this happens every few hours to days
  • the tumour will undergo hypoxia
  • the tumour will resist the radiation more
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5
Q
  1. What is Hypoxia?
A
  • this is when the tumour does not have enough oxygen
    available to maintain homeostasis
  • this happens at the tissue level
  • it makes the tissue more sensitive
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6
Q
  1. What is Repopulation?
A
  • this happens every few weeks
  • healthy and malignant cells will repopulate
  • this happens after irradiation
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7
Q
  1. List the 4 Fractionation Schemes.
A
  1. Conventional
  2. Hyper-Fractionation
  3. Accelerated Fractionation
  4. Hypo-Fractionation
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8
Q
  1. When it comes to Conventional Fractionation,
    what is the:

8.1. Dose per fraction
8.2. Fractions per week
8.3. Total dose
8.4. Issues

A

(8.1) 1.8 to 2.2 Gy

(8.2) Five

(8.3) 45 to 50.4 Gy

(8.4) - it can be too slow for the fast growing tumours
- the dose is too low for resistant cancers

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9
Q
  1. When it comes to Hyper- Fractionation,
    what is the:

9.1. Dose per fraction
9.2. Fractions per week
9.3. Total dose
9.4. Issues
9.5. In which circumstance it is used

A

(9.1) 1.1 to 1.3 Gy

(9.2) Ten
- these treatments are given more than once a day

(9.3) 70 to 80 Gy

(9.4) - it is a burden on patients and staff
- it is a burden on the equipment
- no clear benefit has been demonstrated

(9.5) - it is used to avoid late complications of the normal
tissue

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10
Q
  1. When it comes to Accelerated Fractionation,
    what is the:

10.1. Dose per fraction
10.2. Fractions per week
10.3. Total dose
10.4. Issues
10.5. In which circumstance it is used

A

(10.1) 1.4 to 2.5 Gy

(10.2) Ten
- these treatments are given more than once a day

(10.3) 40 to 50 Gy

(10.4) - it is a burden on patients and staff
- it is a burden on the equipment
- it has acute reactions
- the total dose is delivered for a shorter period of
time

(10.5) - it is used for fast growing tumours

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11
Q
  1. When it comes to Hypo- Fractionation,
    what is the:

11.1. Dose per fraction
11.2. Fractions per week
11.3. Total dose
11.4. Issues
11.5. In which circumstance it is used

A

(11.1) above 2.5 Gy

(11.2) 1 to 5

(11.3) 20 to 55 Gy

(11.4) - it has acute reactions
- the total dose is delivered for a shorter period of
time

(11.5) - it is used for highly conformal treatments

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12
Q
  1. Does this example of Conventional Fractionation make sense?
A
  • yes
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13
Q
  1. Does this example of Accelerated Fractionation make sense?
A
  • yes
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