Radiotherapy is a science about use of ionizing radiation (IR) mainly to treat malignant tumors.
The first time of using X-rays was in 1896.
Principles of Radiation Oncology - e a r l y diagnosis
Clinicobiologic foundations of RT of Tumors
The therapeutic use of IRs is based on their b I o l o g I c a l action, that is, their ability to cause changes in cells, tissues, organs, the body as a whole. It depends on the ABSORBED DOSE (AD) – e n e r g y transmitted to irradiated tissues (Gr).
Principles of Radiotherapy
1.Delivery of an o p t i m a l dose to the tumor.
2. M i n i m a l damage
to surrounding organs & tissues.
3. Carrying out measures stimulating p r o t e c t i v e forces of the body.
Treatment of tumors may be:
RADICAL RT– complete cure of the patients –Indications: an early stages (I-II).
PALLIATIVE RT - a temporary improvement of patients life, life prolongation. stages (III- IV).
SYMPTOMATIC RT - to alleviate the most several manifestations of disease
Contraindications for RT
grave patient’s state, cachexia, anemia, leukopenia, acute septic states decompensated states of the heart,
the liver, the kidneys.
Extension of tumors to adjacent hollow organs, growth into great blood vessels. An inflammatory process.
Cell Radiosensitivity (its reaction to irradiation) depends on patient’s age, state,
on the state of tissues surrounding the tumors,
the presence of hypoxic & anoxic cells,
the proliferation level & cell differentiation.
Mildly hypoxified cells are radioresistant.
Management of radioactive reactions of tumors & normal tissues.
Selection of an irradiation regimen:
delivery of an optimal total tumor dose (TTD).
Radiosensitivity of healthy & tumor cells is practically the same.
The r a d i o t h e r a p e u t i c i n t e r v a l is a difference between radiosensitivity of
the tumor & that of its surrounding healthy organs & tissues.