Prepared: Igor Leskiv Department of oncology and radiology



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Technology basis radiotherapy. Complex, combine and joining methods radiotherapy of neoplasm. Radial reaction and damages.

  • Prepared: Igor Leskiv

  • Department of oncology and radiology


Radiotherapy

  • 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.

  • Active TB.

  • Extension of tumors to adjacent hollow organs, growth into great blood vessels. An inflammatory process.



Cell Radiosensitivity

  • Cell Radiosensitivity (its reaction to irradiation) depends on patient’s age, state,

  • on the state of tissues surrounding the tumors,

  • histologic structure,

  • 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.

  • It should be increased



TNM – clinical classification



The histological structure of the tumor to a great degree determines the effective absorbed tumor dose.



The radiation rhythm or fractioning regimen- the timing of the dose absorption. As a rule the total dose is divided into separate fractions.

  • Small fractioning – 2 Gr 5 times a week –

  • for tumors with high & moderate radiosensitivity.

  • Average fractioning - 3-4 Gr 3-4 times a week

  • for resistant tumors.

  • Large fractioning – 4 Gr & more (10 Gr).

  • It depends on the tactics of treatment.

  • The uninterrupted regimen lasts for days & weeks.

  • One-stage irradiation.



Means of r a d I o m o d I f I c a t I o n - for damage of tumor

  • Oxygenous effect:

  • Oxybaroradiotherapy

  • Hypoxiradiotherapy- gaseous hypoxia-protection of N tissues

  • Chemical compounds.

  • R a d i o s e n s i b i l i g e r s

  • .

  • Hyperglycemia & hyperthermia.

  • Polyradiomodification is carried out.



Clinico-dosimetric planning of RT

  • The main clinico-dosimetric task is to create the most favourable spatial distribution of absorbed radiation doses

  • in patient’s body. EXTERNAL BEAM THERAPY



R a d I a t I o n B e a m s:

  • For X-rays generated at a voltage of 100 keV :

  • 100% of the dose remain on the skin, therefore the single skin tolerable dose (STD) = 2 Gr .

  • Rapid & steep drop of the dose.

  • only for treating surface masses.



R a d I a t I o n B e a m s

  • Gamma-units charged with Co-60 emiss a photon beam (1.17-1.33 MeV) of great energy!

  • A maximum absorption – at a depth of

  • 0,5 cm under skin. STD of 4 Gr.

  • For treating deep tumors



Linear accelerators generate brake radiation & election beams.

  • Linear accelerators generate brake radiation & election beams.

  • Brake radiation of high energies in 25 MeV – the maximum AD is at a depth of 4-6 cm.

  • .

  • Electron beams of high energies –

  • a maximum AD at a depth of 1-3 cm,

  • a rapid drop of the dose.

  • For tumors which do not lie deep.



R a d I a t I o n B e a m s

  • For deep tumors we use beams of h e a v y charged particles (protons, alfa, pions).

  • The adjacent tissues are not factually irradiated.

  • Synchrocyclotron



Methods of RT

  • Distancional methods.

  • Contact method.

  • Distancional irradiation:

  • /External Beam Therapy/ E x p o s u r e.

  • A notion “distance-source-skin” (DSS) is used.

  • D i s t a n c i o n a l (Remote irradiation) –

  • the DSS is equal to 30 cm – 1.5-4 m. More often – 50-80 cm.

  • S u p e r f I c I a l therapy – 1.5-25 cm, more often – 1.5-7.5 cm.

  • Superficial X-ray therapy is used only for skin tumors.



Devices for Distancional Irradiation

  • The linear accelerator generates

  • high-energy electron or proton beams.

  • Gamma-units for mobile, static, movable & intracavitory therapy.

  • a radiation source – Co 60.

  • The half-decay period is equal to

  • 5.3 years.

  • The superficial X-ray-therapy unit.

  • Synchrocyclotrons for receiving protons & cyclotrons for neutron radiation.



Method of patient’s irradiation

  • S t a t i c irradiation can be performed through:

  • single field technique,

  • multiple field technique.

  • M o b i l e irradiation:

  • Rotational



The form the working beam we use : compensators (boluses) from tissue equivalent materials

  • The form the working beam we use : compensators (boluses) from tissue equivalent materials

  • wedge

  • screen filters

  • lead & splitting blocks



Contact Methods of Irradiation (Brachytherapy)

  • The application method – placement of radiation sources above the superficially located tumors

  • the skin, mucous membranes) not more than

  • 1-2 cm deep.

  • The i n t r a c a v I t o r y method : insertion of the radioactive source in the organ cavity. Linear or volumetric sources are shaped.



Brachytherapy

  • I n t r a t i s s u e method:

  • a radioactive preparation is inserted directly to tumor tissue.

  • A high dose is continuously created.

  • Caesium needles & tubes are used for intratumoral & intracavitary cancer therapy.



R a d i o s u r g i c a l method-intraoperative exposure of tumors

  • R a d i o s u r g i c a l method-intraoperative exposure of tumors

  • is carried out in the operation table;

  • or sources with a short half-decay time are implanted into the inoperable tumor



Sources of Radiation

  • Closed sources of radiation exclude ingress of radioactive substances into the environment.

  • needles & tubules with

  • Cs 137,Co 60 , radium, irridium etc.



Sources of Radiation

  • .

  • Outer sources: I 131, P 32, Sr-89, colloidal solutions of ittrium.

  • The use of outer radioactive preparations for oral administration or administration into the blood is a variety of the contact method



Body Reactions to Irradiation:

  • General & local reactions – accompany the therapy & resolve without any special treatment.

  • General: the CNS disorders, a decreased tonus, flaccidity, high irritability, loss of appetite, the CVS disorders, indigestion, hematological shifts .

  • Treatment: vitamins, liquid, antihistamines, hemopoietic stimulators, antibiotics.



Local Skin Reaction:

  • Erythema - reddening, dry radiodermatitis

  • pigmentation & thinning of the skin develops.

  • P r e v e n t I o n: indifferent powders, cod-liver oil, sea-buckthorn oil, mednisolone, methyluracylic ointments.

  • Local reactions of mucous membranes:

  • pain, dysphagia, radioepitheliites, colites ect.

  • Prevention:sanitation of the cavities, sparing, disinfectant solutions, oils, novocain.



Local Radiation Damage

  • There are subcutaneous scleroses,

  • ulcers, pneumonites, colites, rectosigmoitites, dystrophic changes in bones, indurative edema, myelitis, radiation cancer.

  • Radioinduced sclerosis.

  • A special treatment is required.



RT of NON-TUMOUR DISEASES

  • It is carried out only according to strict indications when other methods failed.

  • Single & total doses should be small in the range of

  • 0.1-0.7 Gr every alternate day up to a TTD of 4-7 Gr.

  • The basic method is a direct local irradiation of the focus using the distancional technique,

  • Radiation fields according to the focal size.

  • The X-ray unit or distancional therapy are used in deep foci (more often X-ray therapy ).



Inflammatory processes

  • Boils, carbuncles, hydrodenites, panaritia, thrombophlebites, erysipelatous inflammatory anastomositis, osteomyelitis.

  • We cause local plethora, an increased permeability of capillaries, formation of bioactive substances, lymphocytolysis.

  • The principle of treatment – the more the process, the lower the dose.

  • At the initial stage, it is possible to terminate the process, alleviate pain, relieve inflammation.

  • At phase of necrosis and purulation - rapid infiltrate melting & its delimitation.

  • At the phase of regeneration – rapid wound epithelisation.



  • Periarthritis, deforming arthrosis with the pain syndrome, calcaneal bursitis, osteochondrosis.

  • We lower the pain syndrome – act on immunospecific reactions of articular tissues & nerve receptors.

  • Distancional irradiation.

  • A dose of 0.3-0.5 Gr, a total dose of 3-5 Gr every 48 hours. An effect can be obtained in 4-6 weeks.

  • Neurologic disorders

  • inflammatory disorders of the CNS – neurites, neuralgias, radiculites.

  • Irradiation of nerve centers, roots of cranial &

  • spinal nerves.

  • The postamputation pain syndrome.

  • We irradiate the stump, reflexogenic areas



Organs & Tissues Radiosensitivity

  • - Bony brain, gonads.

  • - Lens of the eye, thyroid, cartilages, fat tissue, lungs, muscles, liver, kidney, spleen, digestive canal.

  • - Skin, bones, extremity.

  • Lymphatic tissue, bony brain, gonads, mucous membranes, skin, cartilages, vascular system, endocrine glands, internal organs, bones, nervous system.

  • age: young & old.





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