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Radiotherapy treatment at the Clínica
Radiotherapy uses ionising radiation for therapeutic purposes. It works by directly or indirectly damaging cellular DNA which is responsible for producing the functional and/or structural mutations that ultimately causes the cells' death.
The most common way of administrating external radiotherapy is to use a linear accelerator.
Linear accelerators have replaced the use of conventional cobalt radiotherapy units as they are more versatile and improve the distribution of the radiation dosage to tumours deep inside the body.
The linear accelerators are able to produce and accelerate electrons generated in a thermal filament on to which it applies the potential difference (electric current) and accelerates the electrons. When the electrons hit the tungsten plate, they produce photons. The electrons are used to treat superficial tumours and the photons are used to treat deeper tumours.
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The Clínica is an international reference centre for intraoperative implants and postoperative radiation treatments with high dose rate brachytherapy.
In external radiotherapy, the source of radiation is further away from the patient and it uses high energy irradiation rays with a large capacity to penetrate tissue.
The equipment that generates external radiation includes cobalt radiotherapy units (producing 1.25 MeV photons), linear accelerators (producing photons of more than 4 MeV and electrons of more than 6 MeV), cyclotrons and synchrotrons (producing protons).
External radiotherapy is classified according to the purpose of the treatment in radical radiotherapy. When applied exclusively (being the only treatment that the patient needs) adjuvant and complementary radiotherapy are administered before or after the main cancer treatment. Prophylactic radiotherapy is used if the aim is to prevent the appearance of metastasis in a specific location and palliative radiotherapy is used when the treatment is aiming to reduce the symptoms produced by the cancer's growth.
Additionally, external radiotherapy is categorised according to the combination of other treatments used in postoperative radiotherapy which aims to sterilise the remaining small microscopic quantities of cancer. Preoperative radiotherapy is used to reduce the size of the tumour so that the operation will be less extensive. Simultaneous or concomitant radiotherapy are combined with chemotherapy and intraoperative or preoperative radiotherapy and are administered in the same surgery or immediately afterwards.
Brachytherapy or internal radiotherapy administer radioactive material inside the tumour or affected tissues.
The radioactive sources used are radioisotopes of low-moderate energy with limited tissue penetration. The most frequently used clinical radioisotopes are caesium, iridium, iodine and palladium.
They are administered using fine wires, capsules or seeds and are introduced into the body in sealed containers.
Depending on the location of the applicators (the mechanisms which introduce the radioisotope), the brachytherapy can be intracavitary if entered via a natural cavity (e.g. oesophagus, vagina), interstitial if the radioisotope is inserted directly into the tumour and superficial if the radioisotope is deposited on the surface of the skin.
Depending on how long the radioactive source remains inside the tumour, the brachytherapy implants can be temporary or permanent. The radioactive implants can be a high, medium or low rate and the dose depends on whether the radioactive source releases a dose of radiation in a small, medium or longer amount of time respectively.
Interstitial brachytherapy is commonly used on tumours in the oral cavity, oropharynx, sarcomas, and most recently, in the treatment of low risk prostate cancer.
Low dosage intracavitary brachytherapy is used on gynaecological tumours.
Radiotherapeutic treatment is carried out by a team of specially trained professionals, directed by a radiation oncologist. The doctor is specialised in radiation oncology and prepares, prescribes and oversees the radiotherapeutic treatment plan. They modify the treatment according to the patient's progress, identifying and treating the adverse effects of the irradiation and work with other specialists like oncological doctors and surgeons to provide a multidisciplinary treatment for the cancer.
The medical physicists work rigorously with the radiation oncologists in the planning and administration of the treatment. They supervise the dosimetrist's work and are directly involved in the preparation of complex procedures. Furthermore, they create and direct these high quality treatment programmes and carry out tests aiming to establish how best both the medical team and the irradiation beam can perform the treatment.
The dosimetrists work with the radiation oncologists and medical physicists to select a radiation technique capable of generating the best distribution of the dose of radiation on the tumour, so that the dose of radiation is not directed towards healthy tissues. The work is carried out on computers using complicated algorithm calculations which are capable of processing detailed images.
During radiotherapy, the person responsible for carrying out the irradiation treatment is always supervised by a doctor. They must be meticulous in positioning the patient and keeping them still, making sure that the treatment is carried out appropriately and that a record is kept of the treatment.
The radiation oncology nurse works with the whole team to attend the patient and his family needs, before, during and after the treatment. They must explain the care needed during and after the irradiation, any possible adverse effects and how to treat them. Other health professionals involved in the care of the patient are nutritionists, physiotherapists, dentists and social workers. Before carrying out the radiotherapy treatment, the radiation oncology doctor speaks with the patient and explains the benefits and risks of the treatment as well as alternative therapeutic treatments.
Subsequently, a simulation is done which consists in taking measurements and drawing references on the patient's skin to help the external irradiation beams' accurate entrance through the skin so that it can be carried out in the same way in each treatment session.
The patient is immobilised in a comfortable position, the same position will be used daily throughout the irradiation treatment.
For the immobilisation of the patient, specific equipment is used like thermoplastic face masks, vacuum or catalytic resin mattresses, inclined surfaces, etc. A specific method is selected to immobilise the patient depending on the location of the tumour and the precise techniques< required for the treatment. Once immobilised and securely fixed in place, a CAT scan is done to plan the treatment and collect axial images. These CAT scan images are sent to the computer to virtually plan the irradiation treatment. During the planning, the computer chooses a specific photon energy level, the number of radiation fields (usually 2-4) and the angles of rotation of the head of the accelerator.
It generates a number of treatment plans and the radiation oncology doctor chooses the plan which offers the maximum distribution of the irradiation dose on the tumour whilst minimising the dose received by healthy surrounding organs. Finally, the patient starts the treatment in the same position in which the simulation and planning procedures have been carried out. The virtual reconstructed planning images are compared with the real images of the patient generated by the radiographic film or digital images.
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Generally, treating cancer is carried out by combining surgery, chemotherapy and radiotherapy.
This is not the case for tumours in a very early stage as they can be cured exclusively with radiotherapy. This is another part of the cancer treatment which is usually administered before or after surgery and before, simultaneously or after chemotherapy.
Radiotherapy is also used to alleviate pain and symptoms produced by tumours which have spread to the bones, brain or other locations.
Radiotherapy treatment is painless and the patient doesn't feel a thing, it is administered as an outpatient procedure in daily sessions (fractions), five days a week, Monday to Friday with rest days on Saturdays and Sundays for a total of 25-40 fractions depending on the type of tumour being treated.
Occasionally, the treatment can be interrupted for a day or more if adverse effects arise and it is then resumed when these conditions have improved or disappeared.
During the treatment, x-rays are scheduled for weekly revisions and evaluations with the radiotherapy oncologist and nurse to observe the changes, adverse effects and recommend further treatment.
Patients are usually advised to take certain cautions during and after irradiation like getting sufficient rest, eating a balanced, nutritious diet and paying particular attention to their skin which could be sensitive and reddened.
After the treatment, a follow-up consultation is organised to evaluate the patient's recovery and their cancer's progress.
Alongside the beneficial effect of the radiotherapy to control, alleviate or cure cancer, radiotherapy can provoke adverse effects due to the irradiation of the healthy skin adjacent to the tumour.
Generally, radiotherapy is well tolerated and many patients continue living normally, however, some patients can experience adverse effects that generally arise near the treated area.
Adverse effects of radiotherapy are considered to be acute when they occur during the treatment or the 90 day post treatment period. They are caused by the inflammation from the depletion of progenitor cells in the tissues that grow quickly like skin, the mucous membrane of the oral cavity and the gastrointestinal tract, haematopoietic tissue, hair follicles, etc.
These acute adverse effects are temporary and recoverable due to the healthy tissue's ability to repair itself. They usually appear after the second or third week of treatment and can last a number of weeks after treatment.
The most common symptom is fatigue but it is not usually disabling. Mucositis (inflammation of oral mucous), oesophagitis (oesophagus inflammation), enteritis (small intestine inflammation), epitelitis and dermatitis (skin inflammation), alopecia and medullary aplasia are some of the most common acute adverse effects. Often, it's necessary to prescribe anti-inflammatory treatment or special foods and very occasionally, admission into hospital for hydroelectrolytic replenishment.
The chronic adverse effects are observed 90 days after having finished radiotherapy and are the result of a tissue transformation process caused by the depletion of slow growing cells like those in muscular, renal parenchyma, hepatic and nervous tissue, etc.
These chronic adverse effects are not recoverable and are permanent which is the biggest limiting factor of clinical radiotherapy although the probability of these chronic adverse effects arising is low.
The chronic adverse effects also include xerostomía or a loss of saliva, fibrosis or hardening of subcutaneous tissue, lung or intestine necrosis, neurological damage and, in paediatric patients, a delay in growth, hormonal alterations and the appearance of secondary tumours.