Significance of local radiation injuries • In over 90% of radiation accidents only local injuries occur mainly due to direct contact with source • Most frequent complicating factor of acute radiation sickness (ARS) Module Medical XIII.
Common sources inducing radiation injury • 192Ir • 60Co • 137Cs • Fission products (beta exposure) • 90Sr • X-ray machines • X-ray fluorescence • Cyclotron products Module Medical XIII.
Typical scenarios leading to partial body radiation injuries • finding lost unshielded sources Module Medical XIII.
Common features of local radiation injuries • Occurrence of extremely high local radiation doses causing very severe tissue damages (often result of direct contact with sealed source) • Very steep dose gradient in all directions from centre (“inverse square law”) Module Medical XIII.
Severe radiation injury of hand - Algerian accident withlost 925 GBq (25 Ci) 192Ir source, 1978 Module Medical XIII.
Common features of local radiation injuries • Clinical symptoms may appear relatively late after exposure, or successively from moment of irradiation, following typical clinical course • The earlier the onset of symptoms, the more severe the intensity of exposure • Range of manifestations-erythema, swelling, blisters, ulceration, necrosis and sclerosis. Module Medical XIII.
Factors determining severity of local radiation injuries Module Medical XIII.
Penetration of radiation Cell nucleus Cell diameter 100 cell diameter alpha 1.7 MeV beta 0.15 MeV beta beta 5.3 MeV alpha Auger I I I I I ı 0.001 0.01 0.1 1 10 100 mm Module Medical XIII.
Human skin structure Module Medical XIII.
Penetration of radiation through skin stuctures Alpha radiation is absorbed in superficial layers of dead cells within the stratum corneum Beta radiation damages epithelial basal stratum. High energy ß-radiation may affect vascular layer of derma, with lesion like thermal burn • Gamma radiationdamages underlying tissues and organs Module Medical XIII.
Normal Irradiated Module Medical XIII.
Clinical course of local radiation injuries • Response of skin to ionizing radiation - radiation dermatitis or cutaneous radiation syndrome (CRS) • Types of skin responses - depending on dose: 1. Initial erythema 2. Dry desquamation 3. Erythema proper 4. Moist desquamation 5. Ulceration and necrosis 6. Late effects: dermal atrophy, hyperpigmentation, fibrosis Module Medical XIII.
Blister formation Module Medical XIII.
Moist desquamation On right hand severe blisters developed after irradiation; on left hand epidermis has sloughed.Presence of hyaline fluid gives blisters translucent appearance Module Medical XIII.
Ulceration and necrosis Module Medical XIII.
Hyperpigmentation Module Medical XIII.
Section of normal skin (left) and of healed lesion (right) from same bovine hide. Module Medical XIII.
Diagnosis of local radiation injuries in early phase • Goals: • Establishment of origin of observed local injuries • Considerradiation as a possibility! • Assessment of severity and clinical consequences • Be careful with the early prognosis! • Early dose estimation Module Medical XIII.
Time of onset of clinical signs of skin injury depending on dose of radiation exposure Module Medical XIII.
Thermal injuryprompt pain, severe inflamatory response, death of affected cells and destruction of tissue All types of cells and tissue components damaged Radiation injury initially painless, and evidence of cell death is not apparent until epidermal surface layers are shed and local cell renewal systems have failed Types of cells found in skin vary in their sensitivity to ionizing radiation Differential diagnosis Thermalvs radiation burns Module Medical XIII.
Skin response curves as diagnostic and prognostic means of local radiation injury amputation on day 62 Hand (70 Gy ) Foot (18 Gy -n) Amputation 4.5 years later Module Medical XIII.
Diagnosis of lateradiation induced injuries Goals • Determining extent of damage (especially lesions that become irreversible) • Decision on therapy (conservative/surgical) • Choosing most suitable moment for surgery • Dosimetry Module Medical XIII.
Contact liquid crystalthermography Module Medical XIII.
Thermography Module Medical XIII.
Thermography Module Medical XIII.
Perfusion scintigraphy Phase 2: Blood pool Phase 1: Blood flow Module Medical XIII.
Thermography Normal hand thermography Module Medical XIII.
Later phase of clinical course:thermography Module Medical XIII.
Determination of radiationinduced tissue oedema • MR and CT images: Useful to show early oedema associated with radiation induced inflamatory reaction and deep swelling especially when affecting muscles Module Medical XIII.
Accidentreconstruction Module Medical XIII.
Principals of treatment local radiation injuries– I • Standardized therapeutical protocols (treatment schemes) do not exist Conservative treatment • Pain management • At all stages, especially during blistering (systemic analgesics and local cooling) • Reduction of inflammatory reaction • antihistamines, NSAID, corticosteroids, aloe vera extracts Module Medical XIII.
Principals of treatment-II Conservative treatment • Healing acceleration • occlusive dressings • tetrachlorodecaoxide (TCDO) induces granulation and re-epithelization in erosive skin conditions • Wound cleaning and prevention of infection • antiseptic solutions (boric acid), for ruptured blisters and vesicles neomycin- coated dressing • local and systemic antibiotics only for secondary infections Module Medical XIII.
Principals of treatment-III Conservative treatment • Improvement of local microcirculation • use of systemic vasodilators questionable • pentoxifylline-trental • hyperbaric oxygen therapy • Late phase:lesions are susceptible to reopening due to progressive vasculitis • avoidance of trauma, rehabilitation,skin hydration • use of drugs to reduce fibrosis • interferon-gamma • superoxide dismutase Module Medical XIII.
Surgical treatment-I • Opening overstretching blisters and vesicles • if necessary, but increases pain and risk ofsecondary infection • Reconstructive and plastic surgery • excision of necrosis • full thickness grafting • myocutenous flap or pedicle flap Module Medical XIII.
Surgical treatment-II • Indications for amputation • very severe lesions with destruction of underlying tissue, including vascular damage • intractable pain • lack of infection control Module Medical XIII.
Conclusion • Local radiation injury (or CRS) is a complex pathological syndrome that follows a typical clinical course characterized by excessively prolonged or incomplete healing • Long term and careful clinical observation and evaluation of perfusion and tissue necrosis by scintigraphy, thermography, cutenous laser doppler, CT and MR is essential Module Medical XIII.