Radiation treatment (radiotherapy) is carried out using X-rays and gamma rays of radioactive elements, the essence of the treatment is irradiation of the tumor and metastases by the ionizing radiation.
Concept of the radiotherapy
The principle of radiotherapy in treatment of malignant tumors is based on a harmful effect of radiation on tumor cells, primarily due to damage of tumor DNA.
The main tasks of the radiotherapy are:
- Tumor treatment due to the harmful effect of radiation on tumor cells, primarily due to damage to tumor DNA.
- Tumor reduction due to partial death of tumor cells, and reduction of the viability of the remaining tumor cells. As a rule, the second treatment stage in this case is an operation. The course of radiotherapy reduces the probability of intraoperative spread of tumor cells.
- Influence on the zones of possible spread of tumor cells that will not be removed during the next operation.
- Influence on the surgically non-removable tumor in order to reduce unpleasant symptoms and to improve the quality of life.
Types of the X-ray therapy (radiotherapy):
- External beam RT
- Intracavitary RT
- Combined RT
- Interstitial RT
Radiotherapy can be carried out prior to the surgery (preoperative or neoadjuvant), during the surgery, after the surgery (postoperative or adjuvant).
Modern systems for carrying out the radiotherapy:
- Conformal radiotherapy
- IMRT (Intensity Modulated Radiation Therapy)
- IGRT (Image Guided Radiation)
- IMAT (Intensity Modulated Ark Therapy)
- Stereotactic radiosurgery - SRS -(TrueBeam, Сyber-Knife, Gamma-Knife, etc.)
Stereotactic radiosurgery (radiotherapy)
The method of ultra-precise radiotherapy. In general, stereotactic radiosurgery is not a surgical procedure. However, a single high-precision and high-dose irradiation allows to destroy the tumor in one session without a noticeable effect on the surrounding tissues. To carry out a stereotactic radiation therapy or a session of radiosurgery, the following elements must be present:
- Using the 3D, 4D planning system
- Using the patient immobilization systems during the irradiation session, which exclude the displacement of the patient's body during irradiation.
- Using the high-energy radiation beams focused on the tumor.
- Using the IGRT for constant monitoring and, if necessary, timely correction of the patient's body position or change of irradiation fields.
Stereotactic radiotherapy requires 2 to 5 sessions to be carried out. It is used for the treatment of tumors of lungs, liver, abdominal cavity organs, spinal cord, prostate, head and neck.
To carry out the stereotactic radiosurgery or radiation therapy there is used the following equipment:
Tomotherapy is a modern equipment of radiotherapy of the fourth generation, the unique character of which consists in helical irradiation and in the formation of a fan beam of the ionizing radiation, which allows to equally irradiate the tumors of a large extent. Radioactive emission is sent to the tumor with the highest accuracy, and the built-in computer tomograph determines the shape, size and location of the tumor in an instant before the session start. Tomotherapy can be used for treatment of any tumors, the patient having indications for radiation therapy. It is especially noted a high efficiency and relative safety of tomotherapy in the following tumors:
- head and neck cancer
- prostate cancer
- lung cancer
- liver cancer
- pancreas cancer
- bone marrow cancer and other types of cancer, in which performance of a usual radiation therapy is restricted because of the tissue's high sensitivity to the radiation, as well as in cases of recurrent cancer after radiation and in case of a multiple cancer.
- Gamma-Knife. The impact on the tumor is carried out by high-energy gamma rays. The device generates about 200 precisely directed into the tumor rays, which shoot into the tumor. Modern devices have the function of displacing the patient within 1 mm for a more complete impact on the tumor. The size of the tumor should not exceed 3-4 cm. Treatment is carried out within 1 session. In contrast to the traditional radiation therapy, where a single radiation beam affects the tumor, gamma-knife technology uses several beams of radiation. The dose of each beam is too weak to harm healthy brain tissues, but when they all meet at a single point that corresponds to a brain tumor, a large dose is obtained, which affects only the tumor.
What types of diseases are treated with a gamma knife?
Treatment with a gamma knife does not require anesthesia, it is enough to use sedatives, so the patient is conscious during the treatment procedure. The patient's head is fixed in one position throughout the course of irradiation. Gamma-knife is used not only for tumors, but also for other diseases of the brain. It is successfully used in treatment of both malignant and benign tumors, as well as in case of metastases in the brain:
- Neurinoma of the auditory nerve
- Metastases in the brain
- Tumors of the pituitary gland
Besides the treatment of the tumor, the gamma-knife is used for vascular malformations of the brain:
- Arteriovenous malformations
- Cavernous malformations
- Arteriovenous fistulas of the dura mater
- (Сyber-Knife) Linear accelerator, which is based on the braking photon radiation. The difference from a gamma knife is that to the use the cyber-knife no fixation and immobility of the patient is required. The fact is that during the irradiation session the sensors of the device constantly check the location of the brain tumor, therefore the radiation beam always falls only on the tumor. This makes the treatment session very comfortable and safe. The working part of the device can move around the patient at different angles. This creates a high cancericidal (tumor lethal) dose of radiation exactly in the tumor focus without damage to surrounding tissues.
In what cases cyber-knife treatment is used?
- Complex pathological foci (tumors) of a brain
- Pathological foci (tumors) of a brain, at which the external radiation therapy is to be avoided
- Recurrence of brain tumor
- Tumors of the brain requiring difficult surgical access
- Patients who for various reasons do not want to perform surgical intervention
The cyber-knife method allows treatment of such tumors that are considered inoperable due to difficult accessibility or when the patient is contraindicated for surgery due to a severe condition.
What brain tumors can be treated with a cyber-knife?
Malignant brain tumors
- Skull base tumors
- Metastases in the brain and bones
- Acoustic neuromas
- Pituitary adenomas
- Other benign tumors
- Head and neck tumors
- Skull base tumors
- Spinal cord tumors
- Mammary gland tumors
- Pulmonary tumors
- Pancreas tumors
- Tumors of retroperitoneal space
- Liver tumors
- Kidney tumors
- Prostatic gland tumors
- Vascular malformations
- Arteriovenous malformations
- Cavernous malformation
- Neuralgia of the trigeminal nerve
Other combined devices with commercial names Novalis TX, XKnife, Axesse, TrueBeam, Trilogy also have the options of stereotactic radiotherapy.