Radiotherapy Flashcards
What is radiotherapy used for
- Used for curative and palliative treatment
name differences between radiotherapy and chemotherapy
Radiotherapy
- uses X rays
- localised
Chemotherapy
- chemical agents
- not localised
How does the radiotherapy machine works
- Linear acceleration head – high ray of X rays come out of the machine
- Kilovoltage – can take X rays when they are in the clinical position
- Beam generation kit used to generate the high energy X rays
- Fire the electrons at the target – uses a wave guide to accelerate them to the speed of light
- Bended round 270 degrees, hit a tungsten target and sprays out the X rays in an uncontrolled position
- In order to control the x rays the radiation field is shaped by multi leaf – parts of lead that moves out of the field independently, shaped the radiation beam to the target
what does conventional radiotherapy do
- Use a series of fixed fields with a fixed aperture shape that is fixed to the target
what are the types of radiotherapy techniques
- Photons
- Electrons
- Superficial X-Rays
- Brachytherapy
- Radioactive treatments
- Protons.
What are photons
Photons: wave like packets of energy
• Deposit energy when they meet matter.
What is the difference between gamma rays and X rays
- Gamma rays: emitted by radioactive decay.
* X-rays: formed by an interaction of electrons with a nucleus.
What is the grey
• The Gray: the unit of absorbed dose.
What is 1 gray
• 1 Gray: deposit of one joule of (radiation) energy in one kg of matter or tissue.
what does 1 gray exposure cause
• 1 Gray: exposure in cells causes:
o >1000 damage DNA bases
o ~1000 single stranded DNA breaks
o ~40 double stranded breaks.
What are the side effects of radiotherapy
- Depends on the area
- If head and neck – discomfort when swallowing
- Side effects last 3-4 weeks after finishing
- 8 weeks to access a response to treatment
How do you keep the patient still and stable during radiotherapy treatment
- Use a shell
How do you prepare the patient for radiotherapy treatment
- Check ID – photo ID, date of birth and name
- Patient underneath the machine
- Place shell over there head and clip it into place
- Set machine in the right position for treatment
- Tends to last 10-15 minutes
- Have to come back every day sometimes for 3 weeks as an example
What is spinal cord compression
- this is an oncological emergency
- seen in patients who have metastasized to the bone and develop new symptoms such as worsening pain, neurological and mobility effecting
- the bones can crumble and this can put pressure of the spinal cord
What are the symptoms of spinal cord compression
develop pain, sphincter discrepancy or neurological issues
what is the treatment of spinal cord compression
- Have to have an MRI of scan and helps them decide best course of therapy – neurosurgery or radiotherapy
- Radiotherapy – given as a course of treatment, can be 1 course or 5 courses over a 5 day plan
What do the fractions mean
- the number of times they have dose
so 15 fractions means 15 times
