14 Radiotherapy Flashcards
Aims of today’s lecture
What is radiotherapy? When is it used? Procedure? Side effects The future of radiotherapy.
Radiation?
Atoms are made up of neutrons protons and electrons
Ionising radiation?
Atoms of natural radioactive substances
with unstable nuclei emit
radioactive decay
Electromagnetic waves i.e. X rays or gamma rays
alpha or ά particles (short range more damaging)
beta or particles
Many radioactive substances emit all three
Some examples of how radiation is used:?
Smoke detectors
Sterilizing medical instruments
Dating rocks and materials such as archaeological finds
Tracers for medical diagnosis
Killing cancer cells
Radiotherapy ?
The treatment of disease by ionising radiation
Radiotherapy
Ionising radiation can penetrate tissues and alter the nuclear material i.e. DNA disrupting cell growth and reproduction
Damaging human cells causing 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.
Advantage – targeted to damage cancer cells – healthy cells can recover
Used in the treatment of malignancies.
Radiotherapy
Schuster (physicist) used X-rays to treat small skin complaints (small cancers
1895 Marie Curie and husband Pierre isolated radium and characterised its properties-
suffered radiation sickness Nobel prize in 1906 (joint) 1911 (MC)
1904 Schuster together with Christie Hosp. started radium therapy – but too expensive
In 1900’s early treatment consisted of a massive dose (up to an hour duration)
major side effects
1930s It conclusively proved that fractionated therapy was just as effective as single-dose therapy, but caused fewer side effects.
“The Manchester system”
Max safe dose in a standardized way.
Radiotherapy
Alpha and gamma radiation are more likely to cause tissue or cell damage because are more effective at producing ionisation.
They are therefore the preferred treatment in comparison to beta radiation or neutrons for treating malignancies
Radiotherapy may 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 or to reduce pain if cancer has progressed and is no longer treatable
To reduce the growth of cells – Graves disease
Palliative radiotherapy
Specifically used to treat malignancies confined to one area
Brain Skin Prostate Breast Uterus
Types of Radiotherapy
External
Supplied from outside the body
Internal
Utilizing radioactive implants placed inside the body
Both treatment aim to be local exposure-targeting specific cells
Each exposure is termed as a fraction
External Radiotherapy
Usually given over several days or weeks Mon-Fri with the weekend off Mark target area -need to lie in a certain position Motionless ~5 min per fraction Painless procedure
Radiotherapy machine
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”.
Conformal radiotherapy (CRT)
3D CRT
Use of metal blocks to direct the beam of ionising radiation
More closely target the shape of the tumour
Routinely used for Prostate Cancer
Internal Radiotherapy (also know as brachytherapy)
May be given once or only a few times
Usually involves a short stay in hospital
Radioactive wires or seeds (radioactive gold or Iodine) put into affected area
A few days (wires or IV)
Permanent (small amounts (seeds) of ionising radiation placed in tumour- degrade over time)
Radioactivity monitored using a Geiger counter
May have to limit contact with people
Internal radiotherapy
May also be given IV or in liquid form
Strontium 89 and Samarium 153(some bone cancers)
Iodine 131(thyroid gland)
Radium 223(secondary bone cancer-trials)
May also used to relieve blockages of the oesophagus
Side effects of radiotherapy
Most people – experience some side effects
Caused by damage to healthy cells- may take time to recover
Dependant on area being treated
Dose of radiation
Physical wellbeing at the time of treatment
Can appear during treatment
Or weeks/months after treatment
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 & sickness
Depends on area receiving treatment
Gastrointestinal 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
Fertility
Loss of libido (tiredness)
Pelvic area- may affect ovarian function in women-induce an early menopause causing infertility
Prostate –impotence/infertility
Risks of Radiotherapy
Increased dose- increases slight risk to normal cells and could cause cancer!
Radiotherapy and the thyroid gland
Graves’ disease
Reduce activity of thyroid gland by destroying cells
Less T3/T4 release
The Future of Radiotherapy
Current research looking into how “fractions” of treatment are given
Hyperfractionated radiotherapy
Hypofractionated radiotherapy
Hyperfractionated radiotherapy
Increasing frequency of fractions-more than one a day
Example Continuous Hyperfractionated Accelerated Radiotherapy
Treatment given over 12 days rather than 4-6weeks
Total dose the same
Requires a stay in hospital
Only available in a few centres
CHARTWEL ( WEEKEND LESS!)
Current clinical trials research- non small cell lung cancer
Some centres adopt this treatment if there has been a delay (patient has been ill or equipment problems)
Hypofractionated radiotherapy
Other current research –increase dose of radiotherapy per fraction lower frequency of fractions.
Overall a reduction in total amount of radiotherapy received
Assess reduction in side effects and reduction in risk of recurrence of the cancer
Stereotactic radiotherapy
Novel treatment 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 consistency of exposure
-damage to nerves.
IMRT & IGRT
Proton and ion beam radiation (conformal proton beam radiation)
Utilises proton beams instead of ionising radiation
Protons in nuclei- release a burst of energy then slow down- less damage to surrounding tissue as don’t penetrate healthy tissues ( heart, lungs, liver..)
Primarily used in the UK to treat cancer of the eye.
Currently tested in Europe on spinal cord tumours, prostate, lung and liver cancers & some children’s cancers
Large dose- reduction in side effects
Early research data is promising
Ashya King suffers brain tumour parents were fighting for treatment – removed child from Southampton Hospital parents wanted to seek treatment in Europe.
Arrested in Spain.
Ashya has now had proton beam treatment in Prague
Important things to remember from this lecture…
What is radiotherapy?
When is it used?
Procedure?
Side effects
The future of radiotherapy.
