Radiotherapy
Compared to radiological and nuclear medicine diagnostics, radiation therapy only for a relatively small but heavily diseased portion of the population employed. At relatively high doses of radiation therapy for a small target volume in the body are used. The aim is the destruction of diseased cells to applied radiation dose in the tumor, while sparing the adjacent healthy tissue largely.
The advances in radiotherapy are based on developments in clinical radiotherapy in combination with modern diagnostic procedures, medical radiation physics, including the computer science and radiation biology. The integration of radiation therapy in complex treatment regimens, such as combined radio-chemotherapy approaches provides new challenges in an interdisciplinary collaboration at the scientific and clinical level. Important developments in recent years include in particular a further improvement of treatment planning, providing optimum, customized, three-dimensional conformal radiotherapy tumor also allows irregularly shaped tumors in anatomically difficult environment.
In the high-energy radiation differently (“hard”) X-rays and gamma rays and elementary particles (eg electrons, protons, neutrons) are used.
The irradiation methods can be one hand on the distance between the radiation source and the tumor to be irradiated and the other divided by the radiation:
Brachytherapy are enclosed radioactive materials (sources) placed directly on the skin (surface contact therapy), inserted into body cavities (intracavitary contact therapy) or, for example in the form of wires, spent surgically implanted in the diseased tissue (interstitial therapy). For the so-called after-loading devices used afterloading. This special intracavitary applicators (eg in uterus, esophagus), interstitial places (such as the prostate) or on the skin. Then the radioactive sources are transported to the desired irradiation site. The radioactive sources are stored in a radiation-proof container of the therapy device. The source of transportation is motorized through catheters, which are connected to the device and the applicators. After end of irradiation, the radioactive sources are returned to the vault of the afterloading device.
In so-called tele-therapy, the radiation source from a distance to the target volume act. Such elements are different irradiation devices:
X-ray irradiation facilities
X-rays have only a small penetration depth and therefore their main effect in the skin, which can cause damage without reaching a sufficient dose in the underlying tumor tissue. The X-ray therapy is therefore preferably used today for surface treatment, ie for the treatment of skin diseases and inflammatory or degenerative diseases of the musculoskeletal system.
Gamma irradiation facilities
The radiation is generated in this type of device by radionuclides such as cobalt -60. Since only the gamma radiation has a greater range and depth of penetration, the resulting additional, unwanted therapeutic alpha-and beta radiation is absorbed by appropriate shielding. The used radionuclide must emit gamma rays, have a high specific activity and a correspondingly large dose of performance and economic reasons, should have a very long half-life. These demands are met primarily cobalt-60.
The disadvantage of these devices are relatively large source diameter and the consequent drop at the edge of the field dose (called penumbra).
Accelerating facilities
For accelerators, electrons are accelerated depending on the device in a vacuum tube.
The most commonly used in radiation therapy system is the linear accelerator, are generated by high-energy photons, so-called ultra-hard X-rays or fast electrons in the mega-electron volt range.
Treatment Techniques
An optimal dose distribution for performing radiation therapy is only taking into account all possibilities of modern technology (diagnostics, radiation technology) can be realized. A suitable irradiation technique be chosen which leads to the desired dose distribution to destroy the tumor with maximum sparing the surrounding healthy tissue. The dose distribution can be significantly influenced by the appropriate
Choice of radiation quality (X-ray or ultra-hard X-rays, electron beams, neutrons, protons),
spatial allocation of one or more sources to the tumor tissue during the irradiation process (eg stay-field, motion irradiation). This must inevitably involve and also affected body tissues are considered.
Treatment planning
The radiotherapy treatment of a patient requires an individual planning, which includes mainly two areas: the medical and physical treatment planning taking into account radiobiological aspects. Essential in this interdisciplinary assessment of tumor involvement is under investigation of modern imaging procedures in order to achieve accurate diagnosis of the tumor occurrence and precise therapy planning an optimal irradiation of the tumor as well as the broadest possible protection of healthy tissue.
Essential for the long-term success of radiation therapy is the careful implementation and coordination of patient care. In the Interdisciplinary guidelines of the German Cancer Society, discusses the principles of modern radiotherapy (radiation oncology) in the individual and on the indications for radiotherapy.
Currently, in Germany every year about 220,000 patients treated with ionizing radiation. Of this total, about 200,000 to 20,000 to the teletherapy and brachytherapy.
Nuclear Medicine Therapy
The radionuclide used the opportunity to directly irradiate the choice of appropriate radiopharmaceuticals, ie unsealed radioactive substances in or on the tumor cell. The most common example is to the radionuclide iodine-131 call, which largely accumulates in thyroid tissue, where it destroys his radiation such as tumor cells. In 1999, about 60,000 radioiodine therapy of benign and malignant thyroid disease with iodine-131 were performed. Other important applications are the radiosynoviorthesis, ie the treatment is extremely painful joints, and the palliative treatment of painful bone metastases. Increasing importance radioimmunotherapy, are at the specific radiolabeled antibodies directed against tumor cells to destroy cancer cells by radiation. The German Society of Nuclear Medicine (DGN) is issuing guidelines to include recommendations in addition to clinical quality control in diagnostics including those in nuclear medicine therapy. Specifically, in each case the rationale, definition, indications and implementation of therapy and still open questions.
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Cancer, Medical News, Medicine | Tegoeh Chuzy | September 22, 2011
Body Cavities, cancer, Clinical Radiotherapy, Electrons Protons Neutrons, Medical Radiation Physics, modern diagnostic procedures, nuclear medicine diagnostics, Nuclear Medicine Therapy, radiation, Radiation Biology, radiation therapy, radioiodine therapy, Radiotherapy, radiotherapy treatment, Target Volume, Treatment planning, Treatment Techniques, tumor, X-ray therapy
