Radiotherapy

When is radiotherapy required?

Radiotherapy is used to treat some, but not all, types of cancer. Sometimes it is used as the only treatment, other times, in combination with other treatments, such as surgery or chemotherapy. The objective is to reduce the size of the tumour before surgery or to destroy the tumour cells after the surgical procedure.

How does it work?

In order to apply this treatment, the linear accelerator and the cobalt unit are used. For the duration of the treatment, between 1 and 7 weeks, patients must come to the Hospital daily to receive it. During this time, the total dose of radiation is distributed per session. The duration and number of the sessions depends on each individual case.

Radiotherapy acts on the tumour and destroys malignant cells, preventing them from growing and reproducing. This type of treatment is based on the use of ionising radiation and is painless.

Treatment phases

• Planning: the patient is placed in the treatment position in the CT (computed tomography). In some cases braces are used to keep the patient in position. Other times, an immobilisation mask is used. Then a CT is carried out at the position where the treatment is to be applied and reference points are drawn.
• Defining treatment volumes: the doctor delimits the area to be treated and the healthy tissues that must be protected on the CT images on the computer. The dose and the number of doses to be applied is decided by the doctor.
• Physical dosimetry: the physicist performs the appropriate calculations to make sure the treatment can be performed according to the doctor’s instructions.
• Verification of the treatment: Once the treatment is planned, patients go to the treatment unit, and in the same position where the planning CT was carried out, x-rays are taken with the accelerator. Using these images, the team confirms the plan is correct.
• Treatment: It consists of several short sessions, usually daily, from Monday to Friday. The patient rests on Saturdays, Sundays and holidays. The same position is used in all sessions. During treatment, the patient is monitored by video camera and microphones to deal with any incident and avoid interrupting the treatment. Control x-rays may be taken periodically.
• Monitoring during treatment: patients usually go for a weekly visit to the doctor, who evaluates tolerance to treatment and the possible acute effects of radiation.

Risks

Radiotherapy treatment can cause a series of side effects that appear during the course of treatment, in the part of the body that is being treated. They are different in each person, and can be more or less intense. They are stronger if the patient is receiving chemotherapy during radiotherapy. The most frequent effects are changes to skin and tiredness, as well as nausea and vomiting, hair loss in the treated area, inflammation in the mouth, lack of saliva, difficulty in swallowing food, diarrhoea or discomfort while urinating.

Radiotherapy treatment can also cause a series of effects that appear years after treatment and can become chronic. These are infrequent, but can occur. It depends on the part of the body in where the treatment is received, the amount and duration of the radiotherapy and whether chemotherapy was also received.

Some longer-term side effects are: changes in the brain such as loss of memory or difficulty in moving, infertility, arm oedema, changes in the mouth (lack of saliva, tooth decay, bone damage) or secondary tumours.