Radioactive sourcesRadioactive sourcesRadioactive sources are present in the sealed (normally non spreadable) and unsealed form (spreadable):
GammagraphyGammagraphy essentially uses as sources essentially uses as sources iridium-192 and sometimes cobalt-60 iridium-192 and sometimes cobalt-60
NeutrongraphyNeutrongraphy uses sources of neutrons like uses sources of neutrons like californium-252 or an americium/beryllium californium-252 or an americium/beryllium couple. couple.
BetagraphyBetagraphy uses beta sources like carbon-14. uses beta sources like carbon-14.
Chemical and biological radiation-treatmentChemical and biological radiation-treatment uses gamma radiation sources cobalt-60 or uses gamma radiation sources cobalt-60 or caesium-137. caesium-137.
Radioactive sources in medicineRadioactive sources in medicine
In medicine there are three uses In medicine there are three uses for non-sealed radioactive nuclides:for non-sealed radioactive nuclides:
Biological analyses:Biological analyses: radio-markers have been replaced radio-markers have been replaced progressively by non-radioactive markers. progressively by non-radioactive markers.
Medical imaging:Medical imaging: nuclear medicine department use nuclear medicine department use radio-pharmaceuticals for diagnostics, which are radio-pharmaceuticals for diagnostics, which are ingested by the patient to obtain an image of the ingested by the patient to obtain an image of the tissue or organ while it is functioning.tissue or organ while it is functioning.
Therapy:Therapy: radio-pharmaceuticals can constitute the radio-pharmaceuticals can constitute the treatment itself, for example iodine 131 for the treatment itself, for example iodine 131 for the treatment of thyroid cancer. treatment of thyroid cancer.
Contamination sContamination sourceourcessreactor accidents involving damage to the core reactor accidents involving damage to the core leading to combined inhalation-peroral entry into the leading to combined inhalation-peroral entry into the body of a mixture of fission products (primarily body of a mixture of fission products (primarily of of volatile volatile caesium and iodine isotopes)caesium and iodine isotopes)
accidental violation of the regulations or procedures accidental violation of the regulations or procedures governing work with radioactive substances, governing work with radioactive substances, especially in form of powder or solution especially in form of powder or solution
accidents involving leaking or damaged sealed accidents involving leaking or damaged sealed sources (i.e. sources (i.e. 192192Ir, Ir, 137137Cs, Cs, 6060Co, Co, 226226Ra) Ra)
errors in dosage of radionuclides used for errors in dosage of radionuclides used for diagnostic and therapeutic purposesdiagnostic and therapeutic purposes
accidents involving the fabrication and reprocessing accidents involving the fabrication and reprocessing of nuclear fuels and the transportation and disposal of nuclear fuels and the transportation and disposal of radioactive wasteof radioactive waste
Goiania Goiania aaccidentccident
Area of contamination – 4 000 000 m2
249 contaminated (137Cs) persons, 129 with internal contamination, 4 deaths
External External rradionuclideadionuclide contaminationcontamination
External External contamination:contamination:
radioactive materials in form of dust, radioactive materials in form of dust, solid particlessolid particles, aerosols, aerosols or liquid, or liquid, becomebecome attached to skin or clothes attached to skin or clothes
External contaminationExternal contamination
The risks linked to external exposure of the skin differ according to the type of radiation:alpha emitting radio-elements do not a priori present any risk by external contamination, beta emitting radio-elements do present a special risk because they entail exposure which is almost exclusively of the skin, gamma emitting radio-elements pose the same problems by external contamination as in external exposure, external contamination by a neutron emitting radio-element is impossible.
External contamination reveals a secondary potential risk of internal contamination by inhalation, ingestion or breaking and penetration of the skin.
People involved in the Chernobyl accident in 1986
The Chernobyl accident, 26 April 1986, involved the very The Chernobyl accident, 26 April 1986, involved the very serious irradiation and contamination of a number of people serious irradiation and contamination of a number of people working in the power station and those who immediately working in the power station and those who immediately intervened, it provides a good example of external contamination. intervened, it provides a good example of external contamination.
More than 200 patients were hospitalized in the hours More than 200 patients were hospitalized in the hours following the catastrophe. Before this massive flood of victims, the following the catastrophe. Before this massive flood of victims, the initial efforts to manage the situation were limited to treatment of initial efforts to manage the situation were limited to treatment of the symptoms a full assessment of lesions, treatment of traumatic the symptoms a full assessment of lesions, treatment of traumatic lesions and summary external decontamination. The latter fact was lesions and summary external decontamination. The latter fact was revealed to be particularly damaging as all the patients had revealed to be particularly damaging as all the patients had external contamination by fission products, such as Cs-137, Sr-90, external contamination by fission products, such as Cs-137, Sr-90, or I-131, all of them being beta and some gamma emitters. Beta or I-131, all of them being beta and some gamma emitters. Beta emitters on the skin caused severe radiological burns with complex emitters on the skin caused severe radiological burns with complex development. development.
It is estimated that 5 of the 28 premature deaths following It is estimated that 5 of the 28 premature deaths following the accident were attributable in part to radiological burns. These 5 the accident were attributable in part to radiological burns. These 5 deaths, and perhaps others, could doubtless have been avoided if deaths, and perhaps others, could doubtless have been avoided if good external decontamination of all the exposed subjects had good external decontamination of all the exposed subjects had been carried out in the shortest time. been carried out in the shortest time.
External External contamination triagecontamination triage
Triage following known or suspected radiation accidents includes both medical and radiological considerations
Medical triage should be based upon local procedures for medical management of persons involved in accidents with radioactive materials and on considerations dependent on the severity of injuries. Treatment in life threatening conditions has priority over considerations for exposure to or contamination with radioactive materials. Following medical stabilization of the patient’s condition, careful radiological assessment can be directed to determining the presence of both external and internal contamination.
External External contamination contamination mmeasurementeasurement
Proper monitoring of patient can detect and Proper monitoring of patient can detect and measure alpha, beta or gamma emitters; measure alpha, beta or gamma emitters; radiation type depends on isotope in radiation type depends on isotope in contaminantcontaminant
Alpha monitor
Radiological surveyRadiological survey
The results of the radiological survey should be recorded on an anatomical chart and made a part of the patient's medical record
Initial external contamination survey (of skin, eyes, lips) should be made with instruments adequate for the particular situation
Decontamination proceduresDecontamination procedures
Start with gentle stream of warm waterStart with gentle stream of warm waterUse mechanical action of flushing and/or Use mechanical action of flushing and/or friction of cloth, sponge or soft brushfriction of cloth, sponge or soft brushFor showering, begin with the head and For showering, begin with the head and proceed to the feet proceed to the feet Keep materials out of eyes, nose, mouth Keep materials out of eyes, nose, mouth and woundsand woundsUse waterproof draping to limit spreadUse waterproof draping to limit spreadCover uncontaminated area with plastic Cover uncontaminated area with plastic sheet and tape edgessheet and tape edges
Decontamination techniques and control
• Use single inward movements or circular motion • Then rinse area with tepid water and gently dry using the same motions• After drying, premonitory skin to determine effectiveness of decontamination
Decontamination procedures:Decontamination procedures: body orificesbody orifices
Consideration:Consideration: Orifices need special attention because
absorption of radioactive material more rapid than through skin
Procedures:Procedures: Oral cavity: brush teeth with
toothpaste, frequently rinse mouth with 3% citric acid
Pharyngeal region: gargle with 3% H2O2
Swallowed radioactive materials: gastric lavage
Nose: rinse with tap water or physiological saline
Mouth
Nostrils
Eyes
Ears
Procedures:Procedures:
•Eyes: rinse by directing stream of water or physiological saline from inner to outer canthus while avoiding contamination of nasolacrimal gland
•Ears: - rinse externally with water
- rinse auditory canal using ear syringe
Decontamination procedures:Decontamination procedures: body orificesbody orifices
Useful therapeutic agents for skin decontamination
Common soap or detergent solutionCommon soap or detergent solution for skin and hair; low acidity (pH ~5) for skin and hair; low acidity (pH ~5) recommendedrecommendedChelating agentChelating agentss:: solution of EDTA 10%solution of EDTA 10% for skin or hair for skin or hair
contamination with transuranium, rare earth contamination with transuranium, rare earth and transition metalsand transition metals
DTPA 1% in aqueous acid solution (pH ~4)DTPA 1% in aqueous acid solution (pH ~4) for washing skin after contamination with for washing skin after contamination with transuranics, lanthanides or metals (cobalt, transuranics, lanthanides or metals (cobalt, iron, zinc, manganese)iron, zinc, manganese)
Useful therapeutic agents for skin decontamination
Potassium permanganatePotassium permanganate5%5% aqueous solution should be used carefully aqueous solution should be used carefully not recommended for face, natural orifices and not recommended for face, natural orifices and
genital regionsgenital regions use when conventional washing ineffectiveuse when conventional washing ineffective follow with application of reducing agent, then rinse follow with application of reducing agent, then rinse
with waterwith water
Hydroxylamine or sodium hyposulfiteHydroxylamine or sodium hyposulfite 5% freshly prepared aqueous solutions5% freshly prepared aqueous solutions reducing agents - apply after KMn0reducing agents - apply after KMn044 or Lugol, then or Lugol, then
wash with waterwash with water
Useful therapeutic agents for skin decontamination
Antiphlogistic topical ointment:Antiphlogistic topical ointment: To be applied for To be applied for fixed contamination,fixed contamination,
especially useful for contamination of fingers especially useful for contamination of fingers
Isotonic saline solutionIsotonic saline solution for eyes for eyes
Isotonic 1.4% bicarbonate solutionIsotonic 1.4% bicarbonate solution for for removing uranium from bodyremoving uranium from body
Lugol solutionsLugol solutions for iodine contamination for iodine contamination
Acetic acid solutionAcetic acid solution (pH 4 to 5) or simply (pH 4 to 5) or simply vinegar for decontamination of vinegar for decontamination of 3232PP
Internal Internal contamination contamination
Occurs when people Occurs when people ingest, inhale or ingest, inhale or are injured by radioactive material.are injured by radioactive material. The most frequent points of entry are by inhalation and wounds.
Metabolism of non-radioactive analogue Metabolism of non-radioactive analogue determines radionuclidedetermines radionuclide’s’s metabolic metabolic pathway.pathway.
Paints for luminous watch faces
In the 1920s and 1930s the clock making industry used radium 226 and 228 in radio-luminescent paint for watches. At this time, the risk from alpha emitting radio-elements was almost unknown.
The workers who painted the luminous faces had the bad habit of tapering their brushes with their lips. Every time they did this they ingested several becquerels of radium. The fact that radium and calcium are chemical homologues, resulted in rare bone cancers appearing starting from the 20s, in the form of carcinoma of the sinus of the face.
An epidemiological enquiry demonstrated the link between exposure to radium and the risk of bone cancer in 2,403 workers, whose ingestion of quantities of radium could be evaluated. 64 were suffering from osteosarcoma whereas 2 cases of this type of cancer would have been expected statistically.
Extent of Extent of hhazardazard
FFactors determining extent of actors determining extent of contamination hazardcontamination hazard::
Amount of radionuclidesAmount of radionuclides Energy and type of radiationEnergy and type of radiation Biological and radiological half-lifeBiological and radiological half-life Critical organCritical organ Chemical and physical properties of Chemical and physical properties of
radionuclideradionuclide
Inhalation:Particularly likely with explosion or fire
Particle characteristics important (size, chemical composition, solubility in body fluids)
Ingestion:Critical for general public after
accidental environmental release
Wound contamination Absorption
In order of decreasing frequency, contaminants enter the body by four principle routes:
Intake routesIntake routes
InhalationInhalation
Fate of inhaled particles dependent on Fate of inhaled particles dependent on physicochemical characteristicsphysicochemical characteristics
Soluble particlesSoluble particles ((33H, H, 3232P, P, 137137CsCs)) absorbed absorbed directly into circulatory system directly into circulatory system
Insoluble particlesInsoluble particles ((Co, Co, UU, Ru, Pu, Ru, Pu,, Am Am)) are cleared by are cleared by lymphatic system or by lymphatic system or by mucociliary apparatus above alveolar mucociliary apparatus above alveolar level.level. Most secretions reaching pharynx Most secretions reaching pharynx swallowed, enter gastrointestinal systemswallowed, enter gastrointestinal system
Deposition and Deposition and cclearance from learance from rrespiratory espiratory ttractract
Contaminant's particle size determines deposition in Contaminant's particle size determines deposition in respiratory tractrespiratory tract Particles <Particles <55 microns in diameter may reach alveolar microns in diameter may reach alveolar
areaarea Particles >Particles >1010 microns too large to pass into alveoli, microns too large to pass into alveoli,
deposited in upper airwaysdeposited in upper airways
IngestionIngestion
All swallowed radioactive material enters digestive tract
primarily from contaminated food and water secondarily from respiratory tract
Absorption from the gastrointestinal tract depends on
chemical make-up and solubility of contaminant
Parameters of ingestionParameters of ingestion
Gastrointestinal absorption Gastrointestinal absorption < 10 % for most elements< 10 % for most elements
Elements of high absorption:Elements of high absorption:• radiumradium (20%)(20%)• strontiumstrontium (30%)(30%)• tritiumtritium (100%)(100%)• iodineiodine (100%)(100%)• caesiumcaesium (100%) (100%)
Wound contaminationWound contamination
Open fracture demonstrates wound contamination with depleted uranium shrapnel
Any wound considered contaminated until proven otherwise
PercutPercutaanneeous ous absorptionabsorption
Generally, radionuclides do not cross intact Generally, radionuclides do not cross intact skin, so uptake by this route does not occurskin, so uptake by this route does not occur
Most important exceptions are: Most important exceptions are: tritium, tritium, iodine, caesiumiodine, caesium
Skin wounds, including acid burns, Skin wounds, including acid burns, abrasive scrabbing, abrasive scrabbing, create portal for create portal for particulate contamination to subcutaneous particulate contamination to subcutaneous tissue, bypassing epithelial barriertissue, bypassing epithelial barrier
Internal Internal contamination measurementcontamination measurement: : ddirect irect mmetethhodsods
Thyroid uptake systemWhole body counters
Indirect cIndirect contaminationontamination mmeasurementeasurement
Indirect measurement of contamination includes Indirect measurement of contamination includes nasal swipes to determine respiratory innasal swipes to determine respiratory intake of take of radioactive aerosols,radioactive aerosols, and and also also urine and faeces urine and faeces sampling to establish internal contamination sampling to establish internal contamination
Alpha and beta emitters, the most hazardous Alpha and beta emitters, the most hazardous internal contaminants, detected through bioassay internal contaminants, detected through bioassay samplingsampling
Accurate bioassays require carefully executed Accurate bioassays require carefully executed sampling over time and knowledge of type and sampling over time and knowledge of type and time of contaminationtime of contamination
Managment of Managment of iinternal nternal ccontaminationontamination: : First Action
Life threatening conditions have priorityLife threatening conditions have priority over considerations of radioactive exposure over considerations of radioactive exposure or contamination. Attention to or contamination. Attention to vital functionsvital functions and and control of haemorrhagecontrol of haemorrhage take priority take priority
Contamination levels almost Contamination levels almost never serious never serious hazard to personnelhazard to personnel for time required to for time required to perform lifesaving measures and perform lifesaving measures and decontamination decontamination
Treatment of Treatment of iinternal nternal ccontaminationontamination
Treatment procedures: the sooner started – the more effective
In practice, initial treatment decisions based on accident history rather than careful dose estimates
Basic Basic pprinciples of rinciples of ttreatmentreatment
Reduce absorption and Reduce absorption and internal depositioninternal deposition
Enhance excretion of Enhance excretion of absorbed contaminantsabsorbed contaminants
Current methods Current methods ofof treatment treatment of of
internal contaminationinternal contamination - Saturation of target organ,- Saturation of target organ, e.g.e.g. potassium iodide potassium iodide for iodine isotopesfor iodine isotopes- Complex formation- Complex formation at site of entry or in body at site of entry or in body fluids followed by rapid excretion, e.g. fluids followed by rapid excretion, e.g. DTPA for Pu DTPA for Pu isotopeisotopess- Acceleration of metabolic cycle of radionuclide - Acceleration of metabolic cycle of radionuclide by isotope dilution,by isotope dilution, e.g.e.g. water for water for 33HH- Precipitation of radionuclide in intestinal lumen- Precipitation of radionuclide in intestinal lumen followed by faecal excretion e.g.followed by faecal excretion e.g. barium sulphate barium sulphate administration for administration for 9090SrSr- Ion exchange in gastrointestinal tract, - Ion exchange in gastrointestinal tract, e.g.e.g. prussian blue for prussian blue for 137137CsCs
Diluting Diluting aagents:gents: wwater for ater for tritium - tritium - 33HH
Single exposures are treated by forced Single exposures are treated by forced fluid intake:fluid intake:
Enhanced fluid intake eEnhanced fluid intake e..g. water, g. water, tea, tea, beer, milk beer, milk has dual value of diluting tritium has dual value of diluting tritium and increasing excretion (accelerated and increasing excretion (accelerated metabolism)metabolism)
Biological half-lifeBiological half-life of of ttritium ritium - 10 days - 10 days Forcing fluids to tolerance (3-4 L/dForcing fluids to tolerance (3-4 L/dayay) )
reduces biological half-life to 1/3-1/2 of reduces biological half-life to 1/3-1/2 of normal valuenormal value
137Cs - physical half-life Tp=30 years; biological half-life in adults average Tb=110 days, in children 1/3 of this
Prussian blue effective means to reduce body's uptake of caesium, thallium and rubidium from the gastrointestinal tract
Dosage of prussian blue: one gram orally 3 x daily for 3 weeks reduces Tb to about 1/3 normal value
Ion Ion eexchange:xchange: pprussian russian bblue for lue for 137137CsCs
Ca-DTPA is 10 times more effective than Zn-DTPA for initial chelation of transuranics. Must be given as soon as possible after accident
After 24 hours, Ca-DTPA and Zn-DTPA equally effective
Repeated dosing of Ca-DTPA can deplete body of zinc and manganese
Chelation Chelation aagents:gents: DTPA for heavy metals and transuranic elements
1 g iv. or inhalation in a nebulizer
Initially: 1 g Ca-DTPA, repeat 1 g Zn-DTPA daily up to five days if bioassay results indicate need for additional chelation
Pregnancy: First dose Zn-DTPA instead of Ca-DTPA
Dosage of Ca-DTPA and Zn-DTPADosage of Ca-DTPA and Zn-DTPA
Additional chelating agentsAdditional chelating agents
Dimercaprol (BAL) forms stable chelates, and may therefore be used for the treatment of internal contamination with mercury, lead, arsenic, gold, bismuth, chromium and nickel
Deferoxamine (DFOA) effective for chelation of 59Fe
Penicillamine (PCA) chelates with copper, iron, mercury, lead, gold. Superior to BAL and Ca-EDTA for removal of copper (Wilson’s disease)
Treatment of uranium contaminationTreatment of uranium contamination
In any route of internal contamination, In any route of internal contamination, treatment consists of slow intravenous treatment consists of slow intravenous transfusion of transfusion of 250 mL of isotonic 250 mL of isotonic 1.4 % sodium bicarbonate1.4 % sodium bicarbonate
Local treatment:Local treatment: forfor skin skin contamination, wash with isotonic contamination, wash with isotonic 1.4% solution of sodium bicarbonate1.4% solution of sodium bicarbonate
SummarySummary of lecture of lecture
Attend to life-threatening injuries firstAttend to life-threatening injuries first
Earlier sEarlier skin decontaminationkin decontamination decreases decreases degreedegree of beta burns, lowers risk of internal of beta burns, lowers risk of internal contamination, reduces chance of further contamination, reduces chance of further contamination contamination
Goal of internal contamination treatment:Goal of internal contamination treatment: decrease uptake into circulatory system, decrease uptake into circulatory system, decrease deposition in critical organs, increase decrease deposition in critical organs, increase excretory rate contaminant excretory rate contaminant
Health physicists and medical specialists Health physicists and medical specialists shouldshould advise on advise on risks and benefits of risks and benefits of decorporationdecorporation