The main methods of radiotherapy

radio therapy

1. The Main Methods of Radiotherapy The department of radiology and radiation medicine

2. Historically , the three main divisions of radiation therapy are external beam radiation therapy (EBRT or XRT) or teletherapy , brachytherapy or sealed source radiation therapy, and systemic radioisotope therapy or unsealed source radiotherapy. The differences relate to the position of the radiation source; external is outside the body, brachytherapy uses sealed radioactive sources placed precisely in the area under treatment, and systemic radioisotopes are given by infusion or oral ingestion.

3. Brachytherapy can use temporary or permanent placement of radioactive sources. The temporary sources are usually placed by a technique called afterloading . In afterloading a hollow tube or applicator is placed surgically in the organ to be treated, and the sources are loaded into the applicator after the applicator is implanted. This minimizes radiation exposure to health care personnel. 

4. Particle therapy is a special case of external beam radiation therapy where the particles are protons or heavier ions.  Intraoperative radiation therapy or IORT is a special type of radiation therapy that is delivered immediately after surgical removal of the cancer. This method has been employed in breast cancer ( TARGeted Introperative radiation therapy or TARGIT), brain tumors and rectal cancers.

5. External beam radiation therapy Conventional external beam radiation therapy Conventional external beam radiation therapy (2DXRT) is delivered via two-dimensional beams using kilovoltage therapy x-ray units or medical linear accelerators which generate high energy x-rays . 2DXRT mainly consists of a single beam of radiation delivered to the patient from several directions: often front or back, and both sides. 

6. Conventional  refers to the way the treatment is  planned   or simulated  on a specially calibrated diagnostic x-ray machine known as a simulator because it recreates the linear accelerator actions (or sometimes by eye), and to the usually well-established arrangements of the radiation beams to achieve a desired plan . The aim of simulation is to accurately target or localize the volume which is to be treated. This technique is well established and is generally quick and reliable. The worry is that some high-dose treatments may be limited by the radiation toxicity capacity of healthy tissues which lay close to the target tumor volume. 

7. An example of this problem is seen in radiation of the prostate gland, where the sensitivity of the adjacent rectum limited the dose which could be safely prescribed using 2DXRT planning to such an extent that tumor control may not be easily achievable. Prior to the invention of the CT, physicians and physicists had limited knowledge about the true radiation dosage delivered to both cancerous and healthy tissue. For this reason, 3-dimensional conformal radiation therapy is becoming the standard treatment for a number of tumor sites. More recently other forms of imaging are used including MRI, PET, SPECT and Ultrasound.

8. Stereotactic radiation Stereotactic radiation is a specialized type of external beam radiation therapy. It uses focused radiation beams targeting a well-defined tumor using extremely detailed imaging scans. Radiation oncologists perform stereotactic treatments, often with the help of a neurosurgeon for tumors in the brain or spine.

9. There are two types of stereotactic radiation: Stereotactic radiosurgery  (SRS) is when doctors use a single or several stereotactic radiation treatments of the brain or spine.  Stereotactic body radiation therapy  (SBRT) refers to one or several stereotactic radiation treatments with the body, such as the lungs.

10. Some doctors say an advantage to stereotactic treatments is that they deliver the right amount of radiation to the cancer in a shorter amount of time than traditional treatments, which can often take six to 11 weeks. Plus treatments are given with extreme accuracy, which should limit the effect of the radiation on healthy tissues. One problem with stereotactic treatments is that they are only suitable for certain small tumors.

11. Stereotactic treatments can be confusing because many hospitals call the treatments by the name of the manufacturer rather than calling it SRS or SBRT. Brand names for these treatments include Axesse ,  Cyberknife , Gamma Knife,  Novalis , Primatom , Synergy , X-Knife,  TomoTherapy , Trilogy and  Truebeam .   This list changes as equipment manufacturers continue to develop new, specialized technologies to treat cancers.

12. Stereotactic radiosurgery

13. Despite its name, SRS is not a surgical procedure. The technique provides high-precision radiation delivery to the tumor large dose by passing healthy tissue located near. This distinguishes SRH of standard radiation therapy.

14. The main principles of SRS Methods of three-dimensional visualization and localization, to determine the exact coordinates of the tumor or target organ. Accessories for immobilization and careful positioning of the patient. Clearly focused beams of gamma rays or X-rays that converge on the tumor or other pathological formation. Methods of conducting radiotherapy under visual control, meaning the position of the tumor tracking during radiation cycle, thus increasing the accuracy and effectiveness of treatment

15. Typically, stereotactic radiosurgical intervention carried out simultaneously. However, some experts recommend several sessions of radiotherapy, especially in larger tumors 3-4 cm in diameter. This method of appointment 2-5 treatment sessions is called fractionated stereotactic radiotherapy.

16. SRS and extracranial stereotactic intervention are an important alternative to open surgical procedures, especially for patients with contraindications. In addition, stereotactic intervention are indicated in tumors that are: Located in hard areas for the surgeon. Located next to vital organs. Changes its position at physiological movements such as breathing

17. Radiosurgical procedures used in the following cases: For the treatment of many brain tumors, including: benign and malignant tumors primary and metastatic lesions single and multiple tumors residual tumor foci after surgery intracranial lesions and tumors of the skull base and orbit to treat arteriovenous malformations (AVM), which represent an accumulation of modified or extended form blood vessels. AVM impair the normal blood flow to nerve tissue and prone to bleeding. For the treatment of other neurological conditions and diseases

18. The principle of SRS The treatment does not remove the tumor and only damages the DNA of tumor cells. As a result, cells lose their ability to reproduce. After the intervention radiosurgical tumor size reduced gradually over 1.5-2 years. This malignant and metastatic foci decreased even faster, sometimes for 2-3 months. If SRH is used for arteriovenous malformation, that for several years a gradual thickening of the vessel wall is observed and its lumen is complete close.

19. Gamma Knife is for radiation target organs used 192 or 201 clearly focused beam of gamma rays. Gamma Knife treatment is perfect for small or medium-sized intracranial injuries.

20. Linear accelerators - devices that are widely distributed around the world and used to deliver high-energy X-rays (photon beam). Suitable for treating large tumor foci. The procedure can be performed once or in several stages.

21. The realization stereotaxic surgery requires a team approach. The group attending staff include: oncologist, radiologist, medical physicist, dosimetrist , radiologist / technician and nurse of radiology department.

22. In most cases, after radiosurgical treatment return to normal life is possible in 1-2 days. Side effects are determined by the area of the body affected by radiation. These include: Hair loss in region of exposure Ulceration of the mucous membrane of the mouth and difficulty swallowing Loss of appetite and indigestion Diarrhea Nausea and vomiting Headaches Disorder of urination

23. Radiosurgical treatment using the Gamma Knife system consists of four stages : Setting retaining frame on the patient's head Visualization of the tumor position Treatment plan using a computer program The procedure of radiation .

24. Stereotactic Radiosurgical procedur e usually can be held ambulatory. However, it may be needed a short-term hospitalization. About the supporting of the patient back home doctor must notify in advance . For 12 hours before the procedure it is needed to stop taking food and liquids. It is also important to know your doctor about limitations in taking drugs.