External Beam Radiotherapy

Radiotherapy is typically given as an outpatient at cancer centre in the hospital. A course of external beam radiotherapy is usually from Monday to Friday (although centres are increasingly working weekends) for anything from one single treatment to seven weeks.

External beam radiotherapy is typically carried out as an outpatient procedure which does not require a stay in hospital. However there maybe circumstances if treatments are being given in combination (radiotherapy, surgery, chemotherapy, endocrine therapy, immunotherapy) that becoming an inpatient maybe necessary. Especially if patients feel unwell and need more intensive care.

The radiation oncology team will discuss radiation therapy as a treatment option. The team will assess the patient specific needs, plan and deliver the treatment as well as help with any side effects experienced. 

Before treatment starts, patients usually need a planning CT (computerised tomography) scan. This scan is carried out by therapeutic radiographers (TR) who will guide a patient through this pre treatment session. Patients will need to remove clothing around the areas that require treatment to enable the TR’s to mark the skin which will help guide the treatment delivery accurately. It may also be necessary to create immobilisation devices to help a patient keep still during this CT scan and each day for treatment delivery. These can be thermoplastic masks, vacbag cushions or specific pieces of equipment to aid in comfort. During this planning scan it may be necessary to administer an injection to highlight internal structures within the body but this will be discussed with the patient by their clinical oncologist. It may also be necessary to prepare for the scan before arrival at the clinic but the medical team will advise the patient of any instructions before the scan date if this is the case. 

This scan is used by the clinical oncologist and medical physicists \ dosimetrists to map out exactly where the radiotherapy treatment will be targeted in order to treat the cancer. The planning process can take some time depending on the complexity. Once the plan has been produced and approved there are many checks that need to be carried out before the plan is ready to be delivered to the patient. 

On day one of treatment TR’s will go through the treatment plan and what to expect over the coming weeks. This first day gives the patient an opportunity to ask any questions they may have before receiving their first treatment. 

For external beam radiotherapy treatment, the patient will be positioned on a couch in the treatment room in the same way they were positioned during the CT planning scan. Once in the correct position the RTs will operate the radiotherapy machine (Linear accelerator or Linac) ensuring it delivers the precisely measured dose of radiotherapy from the patients’ treatment plan. The Linac rotates around the patient as they lie on a treatment table. Generally a small dose of radiation (known as a fraction) is delivered each time, adding up to the total dose. This minimises damage to healthy cells, as these cells can recover between treatments, and maximises the damage caused to cancerous cells. Linacs can deliver pinpoint accurate treatment to a very small cancer or treat a larger cancer close to sensitive parts of the body using techniques known as intensity modulated radiation therapy. The whole process typically takes between 10 – 60 minutes and will be completely painless. Patients will need to keep as still as possible throughout the treatment delivery. Some treatment techniques may involve special instructions but these will be fully explained before any treatment is delivered. When the radiation is being delivered patients will be left alone in the treatment room, RTs will be operating the radiotherapy machine from outside. Patients are constantly monitored via CCTV and can be heard at all times via an intercom. The treatment is often repeated each day for a set number of days depending on the type of cancer and the part of body being treated. Throughout the course of treatment, X-rays and \ or CT images are taken and reviewed to assess the position of the patient and whether any adjustments to the treatment need to be made.

Throughout their radiotherapy treatment schedule patients are closely monitored by their oncology team who will provide ongoing information on the treatment and advice on managing any side effects. Once radiotherapy is finished, patients will be given information to support their recovery and contact details if they have any questions. Note; once patients have finished their radiotherapy treatment the medical team will continue to provide ongoing support and advice.

Other types of radiation used

Most commonly photon beams (high energy Xrays, mega voltage MV or kilo voltage KV) are used but you may also have heard of Electron Therapy or Electron Beam Therapy (EBT). This is a type of external beam radiotherapy that uses electrons instead of photons (photons are the most commonly used type of radiation therapy). Electrons do not penetrate the body as deeply as photons and are therefore used to treat more superficial (closer to the skin) areas, this spares the deeper tissues not requiring treatment. Electrons are also delivered by a Linac using a special applicator attached to the head of the machine.

Particle therapy is a form of external beam radiotherapy using beams of energetic neutrons, protons, or other heavier positive ions for cancer treatment. The most common type of particle therapy as of 2012 is proton therapy. Proton Therapy or Proton Beam Therapy, this is a type of external beam therapy that uses protons to deliver radiation dose to the body. Because of how protons react with the tissues of the body it can be directed at a tumour potentially at a more precise depth than photons. In theory the use of protons can reduce the exposure of radiation to normal tissues, but the interaction this beam has within the moving body is still being investigated.