Local rad inj HGy

Information about Local rad inj HGy

Published on April 30, 2008

Author: Reva

Source: authorstream.com

Content

Local Radiation Injury: Symptoms and Dose-Dependent Consequences, Diagnosis and Treatment:  Local Radiation Injury: Symptoms and Dose-Dependent Consequences, Diagnosis and Treatment Lt.col. Horváth Győző, MD. HDF. Medical Corps Inst. of. Health Protection, Dept. of Radiobiology & “Frederic Joliot-Curie” National Research Institute for Radiobiology and Radiohygiene Dept. of Radiopathology B U D A P E S T, H U N G A R Y Medical Education and Inter-Regional Harmonization Program for Nuclear Accident Preparedness. Train-the-Trainer Course. Prague. June 14-18, 1999. Local Radiation Injury No. 1. RADIATION INJURIES ACCORDING TO THE GEOMETRY OF EXPOSURE:  RADIATION INJURIES ACCORDING TO THE GEOMETRY OF EXPOSURE Local Radiation Injury No.2. Definition: Those accidents in which small areas of the body are subjected to very high doses of ionizing radiation while the rest of the body is exposed only to relatively low doses, and therefore the clinical signs and symptoms featuring the acute radiation sickness (ARS) are usually missing, are referred as local radiation injuries. LOCAL RADIATION INJURIES: Scope Of The Problem :  LOCAL RADIATION INJURIES: Scope Of The Problem Significance of local radiation injuries: in more than 2/3 of the radiation accidents only local injuries occur the most frequent complicating factor of the acute radiation sickness (ARS) relatively rare occurrence: - diagnostic uncertainties (especially if radiation exposure is unknown or it is not considered among the possible reasons of the clinical findings) - shortage in universal, established and evaluated treatment schemes Local Radiation Injury No. 3. COMMON SOURCES AND SCENARIOS INDUCING LOCAL RADIATION INJURIES:  Local Radiation Injury No. 4. COMMON SOURCES AND SCENARIOS INDUCING LOCAL RADIATION INJURIES Sources 192Ir 60Co Fission product betas 90Sr X-ray machines X-ray diffraction units X-ray fluorescence Cyclotron products Users Industry (radiography) Medicine (Dg. & Th.) Research, science Typical scenarios leading to partial body radiation injuries: Misoperation or failure during routine operation, the source becomes unshielded -industrial radiography: operators, mechanics -medicine: operators, patients -science (research): operator, researcher Misplaced, lost or stolen sources: - finding and dismantling shielded sources (unawareness or ignorance of hazard) - finding lost unshielded sources - other: suicide or even crime with stolen sources Approximate Surface And Tissue Doses From Common Gamma Emitters :  Approximate Surface And Tissue Doses From Common Gamma Emitters Local Radiation Injury No. 5. Most Frequently Injured Body Regions Part-1.:  Most Frequently Injured Body Regions Part-1. Local Radiation Injury No. 6. Most Frequently Injured Body Regions Part-2.:  Most Frequently Injured Body Regions Part-2. Local Radiation Injury No. 7. COMMON FEATURES OF LOCAL RADIATION INJURIES Part-1.: Dosimetric aspects:  COMMON FEATURES OF LOCAL RADIATION INJURIES Part-1.: Dosimetric aspects Local Radiation Injury No. 8. Occurrence of extremely high local radiation doses causing very severe tissue damages (often as a result of direct contact with the sealed source) Very steep dose gradient in all directions from the centre (“inverse square law”) Actual dose rarely known when the patient is first seen Radiation dose is estimated after the lesion has run its course (usually over several weeks) Mock-up (reconstruction) of the accident from a retrospective scenario is helpful COMMON FEATURES OF LOCAL RADIATION INJURIES Part-2.: Clinical aspects:  COMMON FEATURES OF LOCAL RADIATION INJURIES Part-2.: Clinical aspects Local Radiation Injury No. 9. Missing or abortive clinical signs and symptoms of the acute radiation sickness (ARS) Deterministic effects with well-defined threshold and effective doses, characteristic to the radiation and affected tissues/organs Skin is always involved in some extent Sharp demarcation (border) line between the differently affected areas according to the dose and dose gradient Staged clinical course (prodromal, acute, subacute, chronic and late phases) After high doses severe late consequences: functional insufficiency, increased sensitivity, increased risk of late malignancies FACTORS DETERMINING THE SEVERITY OF LOCAL RADIATION INJURIES:  FACTORS DETERMINING THE SEVERITY OF LOCAL RADIATION INJURIES Local Radiation Injury No. 10. The Cellular Basis of Skin reaction to Ionizing Radiation :  Local Radiation Injury No. 11. The Cellular Basis of Skin reaction to Ionizing Radiation Cells of the basal layer are decreased in number and lose cohesion and intracellular bridging. Intra- and extracellular vacuolation are present. Arrest of mitosis in proliferative layer. Shortened life-span of progenitor cells. Endothelial dysplasia Thickened dermal collagen and elastic fibers. Radiation Induced Depletion of Epidermal Basal Cells Threshold And Effective Doses For The Different Constituents Of The Skin Part-1.:  Threshold And Effective Doses For The Different Constituents Of The Skin Part-1. Local Radiation Injury No. 12. Threshold And Effective Doses For The Different Constituents Of The Skin Part-2.:  Threshold And Effective Doses For The Different Constituents Of The Skin Part-2. Local Radiation Injury No. 13. Pathophysiological Background Of Local Radiation Injuries Part-1.:  Pathophysiological Background Of Local Radiation Injuries Part-1. Local Radiation Injury No. 14. ACUTE AND SUBACUTE PHASE Inflammation: redness (erythema), swelling (oedema), elevated temperature Passive tissue compression: thrombosis, circulation disorders (insufficient blood supply) Tissue atrophy, necrosis: pain, acute ulceration - moderate doses ( > 20 Gy): Epidermal cell depletion (denudation) due to the mitotic death of the epidermal cells basal and viable upper layers with consecutive dry or moist desquamation, blistering of the epidermis and secondary dermal ulceration. - very high doses (>100 Gy surface dose): Acute dermal necrosis within 2-3 weeks (interphase death of endothelial and fibroblast type cells; sometimes moist desquamation and blisters) Pathophysiological Background Of Local Radiation Injuries Part-2.:  Pathophysiological Background Of Local Radiation Injuries Part-2. Local Radiation Injury No. 15. LATE CONSEQUENCES OF SKIN INJURY Epidermal and dermal atrophy: (fragile skin) 1st phase: death of endothelial and fibroblast type cells 2nd phase: smooth muscle cell degeneration and hyalinisation of the small arterioles Insufficient blood supply Late necrosis with skin ulceration: (sometimes without apparent reason) Occlusion of lymphatic vessels with local lymph stagnation: pain, late oedema Hyperkeratotic and fibrotic degeneration of the skin: Epidermal hyperplasia: (hyperkeratosis) Dermal hyperplasia and hypertrophia (fibrosis, cheloid) Decreased immunological defence of the skin with increased sensitivity against infections and other factors Persistent or recurring pain Increased risk of skin malignancies Typical Skin Response Curves After Beta And Gamma Irradiation In Pigs :  Local Radiation Injury No. 16. Typical Skin Response Curves After Beta And Gamma Irradiation In Pigs Skin Reaction Scores: - Slight erythema 0.5 - Bright erythema 1.0 - Erythema and oedema 1.5 - Dry desquamation or Patchy moist desquamation 2.0 - Blisters, marked moist desquamation and erosions 2.5 - Superficial ulceration 3.0 - Necrosis 4.0 Clinical Course of the Cutaneous Radiation Syndrome:  Clinical Course of the Cutaneous Radiation Syndrome Local Radiation Injury No. 17. Diagnosis of Local Radiation Injuries Part-1.:  Local radiation Injury No. 18. Diagnosis of Local Radiation Injuries Part-1. Goals: Establishment of the radiation origin of the observed local injuries Consider radiation as possibility! Assessing the severity and clinical consequences Be careful with the early prognosis! Early dose estimation Means: History Symptoms and physical findings Laboratory tests: - hematology, plasma biochemistry Thermography - infrared and microwave Series of colour photographs Registration of the clinical course on a daily base (setting skin reaction curves) From the Beginning: Diagnosis of Local Radiation Injuries Part-2.:  Local radiation Injury No. 19. Diagnosis of Local Radiation Injuries Part-2. Goals: Determining the extent of damage, (especially those lesions that become inevitably irreversible) Decision on the therapy (conservative and/or surgical) Chosing the most suitable moment for surgery (the dilemma of early or delayed surgery) Dosimetry Means: Blood flow measurements: - vascular scintigraphy Imaging techniques: - CT (computerized x-ray tomography) - Nuclear Magnetic Resonance Imaging Analysing biopsy materials: - histochemical, immunocytochemical studies, hair growth Topographic dosimetry: - reconstruction (mock-up) of the accident using antropomorph phantoms - EPR studies (dental or other sample) Later phase of the Clinical Course: Principals Of The Treatment Of The Cutaneous Radiation Syndrome (CRS) Part-1.:  Principals Of The Treatment Of The Cutaneous Radiation Syndrome (CRS) Part-1. Local Radiation Injury No. 20. Conservative treatment Pain management Reduction of inflammatory reaction Healing acceleration Wound cleaning and Prevention of infection Improvement of local microcirculation In all stages, especially during blistering (systemic analgetics and local cooling) antihistamines, NSAID, corticosteroids, EACA, Aloe vera extracts; SOD? Occlusive dressings, EGF, TCDO; antiseptic solutions (boric acid), for ruptured blisters and vesicles neomycin- coated dres-sing; local and systemic antibiotics only for secondary infections. use of systemic vasodilators is questionable, pentoxifylline, hyperbaric oxygen therapy Quest for standardized therapeutical protocols (treatment schemes) that do not exist for CRS at present. SYMPTOM-ORIENTED TREATMENT OF THE CUTANEOUS RADIATION SYNDROME:  SYMPTOM-ORIENTED TREATMENT OF THE CUTANEOUS RADIATION SYNDROME Local Radiation Injury No. 21. With the kind permission of Prof. Dr. Ralf U. Peter FAF Medical Academy, Munich, Germany PRINCIPALS OF THE TREATMENT OF THE CUTANEOUS RADIATION SYNDROME (CRS) Part-2.:  PRINCIPALS OF THE TREATMENT OF THE CUTANEOUS RADIATION SYNDROME (CRS) Part-2. Local Radiation Injury No. 22. Surgical treatment Opening overstretching blisters and vesicles Necrotomy, resection and amputation Reconstructive and plastic surgery (skin grafting) if necessary, but increses pain and the risk of secondary infections If tissue damage is irreversible or the tissue received doses above that would respond favorably to any conservative therapy. Two challenging problems for physicians: 1. Determining the extent of the damage and deciding which tissue will inevitably become necrotic. 2. Chosing the most suitable moment to perform surgery. Quest for standardized therapeutical protocols (treatment schemes) that do not exist for CRS at present.

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