Radiotherapy Flashcards
What is radiation?
atoms are made up of neutrons, protons and electrons
stability: protons = electrons
What is ionising radiation?
can be:
electromagnetic waves eg. x-rays/gamma rays (gamma most penetrative)
alpha and beta particles
= radiotherapy
ionising radiation can penetrate tissues and alter the nuclear material eg. DNA disrupting cell growth and reproduction
damaging human cells = apoptosis = release of free radicals = further damage to cell
- healthy cells can recover
- used to treat malignancies
What is the most preferred treatment?
alpha and gamma radiation are more likely to cause tissue/cell damage
= preferred treatment in comparison to beta
Why might radiotherapy be used?
- to treat cancer as a stand alone treatment
- to shrink a tumour before surgery
- to reduce cancer returning after surgery
- to control symptoms/reduce pain if cancer has progressed/no longer treatable (palliative)
- reduce growth of cells in Grave’s disease
specifically used to treat malignancies confined to one area eg brain, skin, prostate, breast, uterus
Types of radiotherapy
external:
- supplied from outside the body
internal:
- utilizing radioactive implants placed inside the body
each exposure of radiotherapy is termed as a ‘fraction’
External radiotherapy
usually given over several days/weeks mon-fri with the weekend off mark target area - therefore need to lie in a certain position (motionless) - 5mins per fraction - painless
Conformal radiotherapy (CRT)
3D CRT
used of metal blocls to direct the beam of ionising radiation
more closely targets the shape of the tumour
routinely used for prostate cancer
Internal radiotherapy
also known as ‘brachytherapy’
- may only be given once/ few times
- involves stay in hospital
- radioactive wires/seeds put into affected area
- a few days = wires/i.v
- permanent = small amounts of seeds of ionising radiation placed in tumour, degrade over time
= radioactivity monitored by a Geiger counter
> may have to limit contact with people
- can be given i.v/liquid form
eg. Strontium 89/ Samarium 153 (bone cancers)
Iodine 131v (thyroid gland)
Radium 223 (secondary bone cancer)
- can also be used to relieve blockages of the oesophagus
What causes the side effects of radiotherapy
caused by damage to healthy cells
dependent on area being treated, dose and physical wellbeing at time of treatment
can appear during treatment or weeks/months after
Tiredness
Physical exertion of going for treatment every day
Anaemia - destruction of erythrocytes
Less O2carrying capacity
Extreme cases may require transfusion
Bone marrow affected – pelvis, abdomen, prostate
Diarrhoea
Nausea and sickness
Depends on area receiving treatment eg GI tract, brain
Some people feel sick at beginning, during, post treatment
Alter diet
Prescribe anti-emetics i.e. Domperidone
Dexamethasone, 5HT antagonists, anti-histamines
Loss of appetite
Sore skin
Local reaction to the radiation
Sore and red – avoid irritants
Temporary hair loss in area
Muscle and joint pain
Treatment may cause muscle stiffness in affected area
Swelling of joints
Light exercise/physiotherapy helps
Fertility
Loss of libido (tiredness)
Pelvic area- may affect ovarian function in women-induce an early menopause causing infertility
Prostate –impotence/infertility
Radiotherapy and thyroid gland
grave’s disease
reduce activity of thyroid gland by destroying cells = less T3/4 release
Hyperfractionated radiotherapy
increasing frequency of fractions more than once a day
treatment given over 12 days rather than 4-6weeks
total dose the same
requires a hospital stay
Hypofractionated radiotherpay
increase dose of radiotherapy per fraction but lower frequency of fractions
overall reduction in total amount received
assess reduction in SE and reduction in risk of recurrence of cancer
Stereotactic radiotherapy
used to treat small round tumours usually found in the head
Used to treat a number of benign conditions:
Pituitary adenomas
Acoustic neuromas
Growths at the base of the skull (meningiomas)
- secondary brain tumours or Gliomas
- treatment delivered from many different points in the head
- external frame to keep head in place.
Radiosurgery
a type of stereotactic radiotherapy
patients receive one single large dose of radiation
may be used if patients can’t undergo surgery
not suitable for medium or large tumours dueto consistency of exposure
damage to nerves
Proton and ion beam radiation
utilizes streams of proton particles, which focus more tightly on tumours compared to radiotherapy = more normal tissue is spared
good when tumour is in a sensitive area eg. brain/ when a child is developing
utilises proton beams instead of ionising radiation
large dose = reduction in SE
