Radiotherapy is a technique using ionising radiation created by a Linear Accelerator (linac). The energy of these rays is significantly higher than the x-rays used in medical imaging. Radiotherapy is predominantly used to treat malignancy as either a curative or palliative measure. It is often used to treat tumours a priori but is typically used in combination with surgery and/or chemotherapy. If used after surgery, it is considered “Adjuvant” and if used before other treatments, “Neoadjuvant”.
Non malignant conditions have also been treated including keloid scars, Peyronie’s disease, dysthyroid eye disease, pigmented villonodular synovitis, pterygium,heterotopic ossification and trigeminal neuralgia.
Radiotherapy is administered by Therapy Radiographers directed by a Consultant Radiotherapist (who is a specialist cancer doctor) in a hospital setting. Adjuvant doses are typically 45 – 60 Gray administered in fractions over several weeks. This is given after planning the treatment often using Computed Tomography, followed by “Simulation”.
There are three main types of radiotherapy:
- External Beam
- Unsealed Source
Side effects in the short term include damage to skin, oral, pharyngeal and bowel mucosa, infertility and fatigue. Longer term adverse effects include hair loss, fibrosis, dryness and even cancer.
Another type of radiotherapy administered via the bloodstream is “Radioisotope Therapy”eg 131I for thyroid cancer, Yttrium-90 bound to hormones for neuroendocrine tumours and Metaiodobenzylguanidine (MIBG) for neuroblastomas.