Lecture 3 - Role of Radiation Therapists

Question 1

What is radiotherapy?

Answer 1

Ionizing radiation which aims to kill tumors before they spread systematically, by increasing tumor kill with decreasing kill to body
Used with surgery, chemotherapy, hormone therapy and immunotherapy

Question 2

What is radical radiation therapy and what are some example Gys?

Answer 2

• curative
• high doses to low volumes of tissue
• 25-70 Gy –> dependent on responsiveness of cancer
  e. g. prostate 70 Gy

Question 3

What is palliative radiation therapy and what is an example Gy?

Answer 3

• improve quality of life and symptoms
• quality over quantity –> minimal side effects
• usually low does but can be high
  e. g. palliative spine 30 Gy

Question 4

What is radiation therapy?

Answer 4

Ionisation that damages DNA or ionises water into highly damaging cells = free radicals

• Normal cells can recover
• Cancer cells cannot, no repair mechanism and when they try to replicate = death

Question 5

How do free radicals form and cause damage?

Answer 5

Radiation –> water molecule –> break into H+ and free radical –> free radical looks for hydrogen -> disturbs DNA stand –> damage/killing

Question 6

How is RT produced?

Answer 6

• Accelerating electron into metal
• Old machines radioactive source
• LINAC, higher acceleration = high energy

Question 7

What are the different types of energies and what are they used for?

Answer 7

Kilovoltage kV - 1000 V, will penetrate into body by mostly surface –> used for superficial and skin tumors

Megavoltage MeV or MV - 1,000,000, deposits high does at depth --> known by testing
Examples 
4MV = head and neck 
6MV = thorax
10-18MV pelvis (max 10MV in QLD)

Question 8

What is brachytherapy?

Answer 8

Radioactive source positioned near or in tumor, e.g. oral cavity or prostate/cervix
Less damage to normal tissue, works from the inside out
-Low dose –> never removed, dose over time through radioactive decay
-High dose –> 3 times, 24 hr period

Question 9

What is the pathway for RT prescription?

Answer 9

Referral from GP to RO, RO decides optimal treatment based off experimental data, counsels patient on the use of the therapeutic dose and the side effects

The patient is then booked in for sim with RT

Question 10

What is localisation?

Answer 10

Process in which images are used to identify the tumor and OAR, done through CT by RT

Question 11

How and planning achieved?

Answer 11

By the use of specialist software, and past experimental data to choose the best treatment option and beam arrangement

Question 12

What is the therapeutic ratio?

Answer 12

Adequate dose to tumor vs. dose to patient `

Question 13

What are the steps in planning?

Answer 13

1. imaging
2. dose planning and calculation
3. how to direct rad to tumor
4. minimal dose to normal tissue
5. ensure critical structure are safe –> positioning, stabilization, and reproducible

Question 14

What are the steps in treatment?

Answer 14

RT explain process and potential side effects

1. positioned accurately –> within 5mm
2. imaging check accurate
3. deliver planned RT, observed by CCTV
4. patients attend for 10-15 min for 5-8 weeks

Question 15

Other things RT do…

Answer 15

• ensure safety and accuracy
• provide support and care
• provide advice about RT
• education
• major role in multi disciplinary team
• advocate for patient

Question 16

What are some of the potential side effects of RT?

Answer 16

• general fatigue
• erythema
• transient alopecia
• diarrhea
• nausea

REDNESS –> immune response cellular –> not actual radiation