Radiation treatment (radiotherapy) is carried out using the X-rays and gamma rays of radioactive elements. The essence of the treatment is the irradiation of the tumor and metastases by ionizing radiation.
The concept of radiotherapy
The use of radiotherapy in the treatment of malignant tumors is based on the harmful effect of radiation of tumor cells through its damage to tumor DNA.
The main tasks of the radiotherapy are:
Tumor treatment is based on the harmful impact of radiation on tumor cells through its impact on tumor DNA. Resultantly, there can be tumor reduction due to partial death of tumor cells, and the 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 that tumor cells will be spread during operations (intraoperative spread). It will also address the zones of possible tumor cell spread which will not be removed during operations. It is also possible to impact a surgically non-removable tumor to reduce symptoms and improve the general 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)
This is a method of ultra-precise radiotherapy which largely does not involve surgery. Instead, a single high-precision, high-dose irradiation is directed at the tumor in the hope of destroying it in one session without a noticeable effect on any surrounding tissues. To carry out a stereotactic radiation therapy or a session of radiosurgery, the following procedure will be followed:
A 3D-4D plan will be generated. A patient immobilization system will be used to control the patient's displacement during irradiation. A high-energy radiation beam will be directed at the tumor. An IGRT will be used to constantly monitor, and if necessary correct, the patient's body position or a change in radiation field.
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.
Tomotherapy is a fourth generation, modern form of radiotherapy, the unique character of which consists in its helical irradiation and in the formation of a fan beam of ionizing radiation. This allows the even irradiation of larger tumors, with a computer tomograph mapping the shape, size, and location of the tumor before the session begins to ensure the highest accuracy. Tomotherapy can be used for any type of tumor that can be treated by radiation therapy, and is typified by a high rate of efficacy and safety for 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 the performance of standard radiation therapies are restricted by the tissue's high sensitivity to radiation, or in cases of recurrent cancer after radiation or multiple cancers.
- Gamma-Knife. The tumor is impacted by high-energy gamma rays. The device generates about 200 precisely directed rays which are directed into the tumor. With modern devices, it is possible to direct these with a tolerance of 1mm, but the size of the tumor should not exceed 3-4cm. In contrast to 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 tissues, but the point at which they all meet gets a large dose. This means that only the tumor gets a large dose of radiation.
What types of diseases are treated with a gamma knife?
Gamma-knife treatment does not require anesthesia, with a mild sedative for relaxation often all that is required. The patient is conscious during the treatment procedure with their head fixed in one position for its duration. Gamma-knife is used not only for tumors, but also for other diseases which impact the brain. It is successfully used in the treatment of both malignant and benign tumors, as well as in case of metastases in the brain, such as:
- Neurinoma of the auditory nerve
- Metastases in the brain
- Tumors of the pituitary gland
Besides treating the tumor, gamma-knife can be used to treating vascular malformations of the brain, such as:
- Arteriovenous malformations
- Cavernous malformations
- Arteriovenous fistulas of the dura mater
- (Cyber-Knife) linear accelerator, a process based on braking photon radiation. The difference from a gamma-knife is that during cyber-knife, no restraint of the patient is required. This is because during the irradiation session, the sensors of the device constantly check the location of the brain tumor, and ensure that the radiation beam is always directed towards it. This makes the treatment extremely safe and comfortable, and allows the device to work from a range of different angles. The result of this is a high cancericidal (lethal to the tumor) dose of radiation without damage to the surrounding tissue.
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.