Week 12 - Radiotherapy Flashcards
What gives an atom stability?
The protons = electrons
What is ionising radiation?
Radiation consisting of particles, X-rays or gamma rays with sufficient energy to cause ionisation in the medium through which it passes
What is ionisation?
The process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons to form ions, often in conjugation with other chemical changes
Which atoms emit radioactive decay?
Atoms of natural radioactive substances with unstable nuclei
Name some ionising radiation
- electromagnetic waves (X-rays or gamma rays)
- alpha or á particles (short range - more damaging)
- beta or b particles
Many radioactive substances emit all three
What is radiotherapy?
The treatment of disease by ionising radiation
What is an advantage of radiation?
Targeted to damage cancer cells - healthy cells can recover
How does ionising radiation have an effect on tissues/cells?
- can penetrate tissues and alter the nuclear material (I.e. DNA)
- disrupting cell growth and reproduction
What effect does radiation have on human cells when it damages them and how?
-damages cells - causes apoptosis
- when a high energy ray hits a molecule, it can cause it to break up
- this can form free radicals which can cause further damage to the inside of the cell
- leads to apoptosis
Which radiations are more likely to cause tissue or cell damage and why?
- alpha and gamma radiation
- more likely to cause tissue or cell damage because they are more effective at producing ionisation
Which are the preferred radiations to treat malignancies and why?
Alpha and gamma
-more likely to cause tissue or cell damage because are more effective at producing ionisation
When may radiotherapy be used?
- treat cancer as a stand alone treatment
- shrink tumour before surgery
- reduce cancer returning after surgery
- control symptoms or reduce pain if cancer is no longer treatable
- reduce growth of cells - Graves’ disease
- palliative radiotherapy
Give examples of the malignancies specifically confined to one area that radiotherapy aims to treat
Brain Skin Prostate Breast Uterus
What are the types of radio therapy?
Internal and external
What is external radiotherapy?
- supplied from outside the body
- local exposure-targeting specific cells
What is internal radiotherapy?
- utilising radioactive implants placed inside the body
- local exposure-targeting specific cells
What is each exposure of radiotherapy classed as?
A fraction
How is external radiotherapy given?
- usually given over several days or weeks
- mon-fri with weekend off
- mark target area - need to lie in certain position
- motionless
- 5 mins per fraction
- painless procedure
How does a radiotherapy machine work?
A metal element is heated to produce electrons. These accelerate in an electric field towards a piece of tungsten metal, which then emits high-energy X-rays when they hit it
What is conformal radiotherapy? (CRT)
Use of metal blocks to direct the beam of ionising radiation
-3D CRT
What is an advantage of conformal radiotherapy (CRT)?
-more closely targets the shape of the tumour
What is conformal radiotherapy (CRT) routinely used for?
Prostate cancer
What is internal radiotherapy also known as?
Brachytherapy
How is internal radiotherapy given?
-may be given once or only a few times
-usually involves short stay in hospital
-radioactive wires (a few days)
or
- radioactive seeds (radioactive gold or iodine a permanent - small amounts of ionising radiation placed in tumour - degrade over time) put in to affected area
-IV or in liquid form
-may have to limit contact with people
