Radiotherapy
Radiotherapy
- Therapeutic use of radiation in the management of cancer
- Electromagnetic: photons, x-rays, gamma rays
- Particulate: electrons, neutrons
- Ionizing radiation = amount of energy absorbed per unit mass of tissue (measured in grays)
- Delivery: linear accelerator
- Mechanism of cellular damage
- Damage of DNA - free radical formation leads to chromosomal damage and cellular death
- Can also induce cellular apoptosis
- Amount of damage is proportional to the dose of radiation
Planning treatment
Factors to consider
- Radiosensitivity of tumour?
- Highly sensitive: lymphoma, myeloma, seminoma
- Moderately sensitive: breast, ovarian, teratoma, BCC, Small cell lung carcinoma
- Moderately resistant: cervical carcinoma, bladder carcinoma, rectal carcionma, sarcomas
- Highly resistant: melanoma, osteosarcoma, carcinoma of pancreas
- Extent of tumour
- Tolerance of normal tissues to radiation
- Damage minimized by 3d imaging to ensure maximum radiation dose is delivered to tumour itself
- Moulds created (as in head/neck cancers), tattoos of chest wall in breast cancer (ensure same position each time)
- "Wedge" fields - multiple fields necessary
- + "Shrinking" method to allow margins of treatment to be reduced during last few weeks of treatment
Complications
- Acute
- Fatigue
- Anorexia, nausea
- Skin irradatioatn- erythema/desquamation
- Mucosal irradiation - diarrhoea
- Dysphagia
- Temporary alopecia
- Sterility
- Late
- Telangectasia
- Loss of saliva production
- Pulmonary damage
- Bowel strictures
