63. RADIOTHERAPY: BRACHYTHERAPY CONTINUED

Question 1

1. What will the continuous delivery dose of Brachytherapy influence?

Answer 1

1. THE REPAIR
   
   • of the sub lethal damage
   • of the potentially lethal damage
2. CELL PROLIFERATION
   - this is the rapid increase in the number of cells
3. CELL KINETICS

Question 2

2. What do the continuous delivery dose effects result in?

Answer 2

• they can modify the radiation response of the tumour
• they can modify the radiation response of the normal
  tissues

Question 3

3. What are the 6 types of Brachytherapy implants?

Answer 3

1. Intracavitary
2. Interstitial
3. Surface (mould)
4. Intraluminal
5. Intraoperative
6. Intravascular

Question 4

4. What is an Intacavitary implant?

Answer 4

• the source is place into the body cavities
• these cavities are close to the tumour volume

Question 5

5. What is an Interstitial implant?

Answer 5

• the source are implanted surgically
• they are implanted within the tumour volume

Question 6

6. What is a Surface (Mould) implant?

Answer 6

• the sources are placed over the tissue
• this tissue is to be treated

Question 7

7. What is an Intraluminal implant?

Answer 7

• the sources are placed in a lumen

LUMEN:
- this is the inside space of a tubular structure
- EG: intestine, blood vessel

Question 8

8. What is an Intraoperative implant?

Answer 8

• the sources are implanted into the target tissue
• this happens during surgery

Question 9

9. What is an Intravascular Implant?

Answer 9

• a single source is placed into small or large arteries

Question 10

10. What are the 2 durations of Brachytherapy treatments?

Answer 10

1. Temporary
2. Permanent

Question 11

11. What is a Temporary Brachytherapy Treatment?

Answer 11

• the dose is delivered over a short period of time
• the sources are removed after the prescribed dose has
  been reached

Question 12

12. What is a Permanent Brachytherapy Treatment?

Answer 12

• the dose is delivered over the lifetime of the source
• this is until the source has completely decayed

Question 13

13. What are the 2 Methods of Loading of Brachytherapy Treatments?

Answer 13

1. Hot Loading
2. After Loading

Question 14

14. What is Hot Loading?

Answer 14

• the applicator is preloaded
• there are radioactive sources present in the applicator
• as it is being placed into the patient

Question 15

15. What is After Loading?

Answer 15

• the applicator is placed into the target position first
• the radioactive sources are loaded into the applicator
  later

THEY CAN BE LOADED EITHER MANUALLY:
- by hand

OR THEY CAN BE LOADED BY A MACHINE:
- Automatic Remote After Loading

Question 16

16. What are the 3 types of Dose Rates we use in Brachytherapy Treatments?

Answer 16

1. Low Dose Rate (LDR)
2. Medium Dose Rate (MDR)
3. High Dose Rate (HDR)

Question 17

17. What is the numerical value of the Low Dose Rate?

Answer 17

• 0.4 to 2 Grays per hour

Question 18

18. What is the numerical value of the Medium Dose Rate?

Answer 18

• 2 to 12 Grays per hour

Question 19

19. What is the numerical value of the High Dose Rate?

Answer 19

• greater than 12 Grays per hour

Question 20

20. What factors does the choice of an appropriate Photon Emitting Radionuclide depend on,
    for a specific Brachytherapy Treatment?

Answer 20

1. Photon Energies
2. Photon Beam Penetration
   -into the tissue and shielding materials
3. Half-Life
4. Half-Value Layer (HVL)
   - in the shielding materials
5. Specific Activity
6. Source Strength
7. Inverse Square Fall-off Dose
   - this takes into account the distance from the source

Question 21

21. What does these images show?

Answer 21

• this is a Low Dose Rate Brachytherapy Treatment
• it makes use of Permanent Seed Implants

Question 22

22. What do these images show?

Answer 22

• this is a High Dose Rate Brachytherapy Treatment
• it makes use of Permanent Seed Implants