ROJoson’s Notes on Radiotherapy

Radiotherapy is a treatment to destroy cancer cells with radiation. A beam of radiation is targeted on the cancer, which shrinks it.

Radiotherapy is one of the common treatment modalities for cancer.  Radiotherapy can treat many different types of cancer.

Radiotherapy uses high-energy radiation, such as X-rays and gamma rays. It works by destroying the DNA inside cancer cells. This prevents them from reproducing and therefore shrinks cancerous tumours. Healthy cells will also be affected.

There are two main types of radiotherapy treatment – external radiotherapy and internal radiotherapy.

Radiotherapy is used for the following reasons.

  • To destroy the tumour. Radiotherapy can be used on its own or combined with other treatments such as surgery or chemotherapy. If the aim is to cure your cancer with radiotherapy, this is known as radical radiotherapy.
  • To reduce the size of a tumour before surgery. This is called neoadjuvant treatment.
  • To make sure all the cancer cells are destroyed after surgery. This is called adjuvant treatment.
  • To slow down the progress of the cancer, relieve pain and other symptoms. This is called palliative treatment and is used for advanced cancer.

The number and duration of radiotherapy sessions you have will depend on the type of cancer you have and where it is in your body. You may have one or two treatments with radiotherapy. However, you usually have a course of treatment over days or weeks.

A team of health professionals (a multidisciplinary team) will be involved in your radiotherapy treatment. These professionals will include a clinical oncologist (a doctor who specialises in cancer care using radiotherapy and chemotherapy) and a radiographer. A radiographer is a healthcare professional trained to perform imaging procedures.


External radiotherapy

External radiotherapy delivers radiation to you from an external source. There are a number of techniques for doing this.

One technique is to use a machine known as a linear accelerator. This produces high-energy beams of radiation, either as X-rays or gamma rays. Your radiographer will ask you to sit or lie down in a fixed position. It’s important for your radiographer to position the radiotherapy equipment accurately to target the beam of radiation exactly on the right spot.

The machine may then rotate around you, or it may be fixed in one position. The machine won’t touch you at any point but it can be quite noisy, with whirring and buzzing sounds. Your radiographer will leave the room during your radiotherapy. There is an intercom so you can communicate with him or her at all times.

Other types of external radiotherapy use imaging scans, such as CT scans, and computer technology to map the position of the cancer in your body. This helps to deliver the radiotherapy to the cancer and protects your surrounding tissues better than conventional techniques.

There are also forms of very targeted higher dose radiotherapy, such as gamma knife. These are used for specific types of cancer but may involve just a few treatments at a higher dose than standard radiotherapy.

The type of external radiotherapy you have will probably depend on where your cancer is. Ask your radiographer for more information.

External radiotherapy won’t make you radioactive during or after the treatment because no radiation-producing material gets inside your body. You may be able to carry on with many of your usual daily activities. However, you may feel tired during and after your treatment. It’s a good idea to ask friends and family for help and support if you need it.

The traditional external beam radiation therapy treatment schedule usually requires daily trips to the hospital or cancer center — usually 5 days a week for 4 to 6 weeks.

Internal radiotherapy

In internal radiotherapy, the source of radioactivity will be put inside your body so it can get closer to the cancer. This can be done in two main ways.


In brachytherapy, a doctor or surgeon will put a solid source of radiation within, or next to, your cancer tumour to give you radiotherapy. This harms healthy tissue around the cancer as little as possible.

You can have either temporary or permanent brachytherapy. The type you have will depend on what type of cancer you have.

If you’re having temporary brachytherapy, the source may be left in place for anything from a few minutes to a few days. If you’re a woman and have a gynaecological cancer, such as cervical cancer, the radiation source will be placed inside your vagina during the treatment. For other cancers, you may need to have a minor operation under general anaesthesia to put the radioactive source into your body.

You may need to stay in hospital for a day or two after your treatment. Your visitors will be restricted because you will be radioactive while the source is in place.

If you’re having permanent brachytherapy, your surgeon will place tiny radioactive implants inside your body that will stay in place. For example, if you’re having treatment for prostate cancer, your surgeon will place small radioactive pellets, known as seeds, into your prostate gland. These will deliver a steady dose of radiation to the prostate. You won’t be a risk to others from radiation because the implants only produce a very small amount of radiation. They gradually lose their radioactivity over time.

Radioisotope therapy

In radioisotope therapy, a radioactive substance (a radioisotope) is used to treat your cancer. You can have it as an injection into a vein, or directly into the cancer. You can also swallow capsules or drink a liquid. Radioisotope treatment is often used to treat thyroid cancer.

After radioisotope therapy, your body will give off small amounts of radiation. You may need to stay in hospital for some time after treatment. After that you will need to take precautions to minimise the risk to other people from any radiation. For example, don’t get close to pregnant women or children for several days afterwards. The radioactive material will leave your body in your body fluids, such as sweat and urine. Therefore, your healthcare team may advise you to flush the toilet twice after each use for example.


Some Sources and References:

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