NOVEL RADIATION SHIELDDING FABRIC FOR PERSONAL PROTECTION AGAINST RADIOACTIVE SOURCES Pavel CASTULIK CB 050 Vojenská chemie, toxikologie ochrana před vysoce toxickými látkami Přírodovědecká fakulta Masarykovi university Brno Jaro 2011 Non Destructive Imaging and Evaluation Security Scans Radiation Generating Equipment ■ Healthcare Diagnostic radiography: X-rays are produced only when the machine is activated. X-ray images are viewed on a film or through digital images. Diagnostic fluoroscopy: X-ray images are viewed on a video monitor rather than on film. Fluoroscopy procedures are the largest source of occupational radiation exposure in medicine. Fluoroscopy is used to study moving structures, and to assess positioning during surgical and radiographic procedures. Radiation therapy: Linear accelerators (powerful electron and X-ray beam machines) are used for the treatment of cancer. The energy of the X-ray radiation produced by these units is 10 to 100 times that of a diagnostic X-ray machine. Diagnostic and therapy Radionuclides: Tc-99m, 1-131, P-32, lr-192, Cs-137, 1-125 and Y-90, are frequently used in hospitals. ■ Industrial and security machinery ■ Non-destructive industrial inspection machinery ■ Gauges ■ Fire detectors ■ Sterilization machines ■ Ion implantation machines used in the manufacture of electronic chips ■ Baggage screening machines ■ Personnel screening machines ■ Research nuclear reactors ■ Portable nuclear power generators ■ Orphan sources Radiation Sources 1Ü* mCi it^ — *= jiCi o "§ nCi Qc —' Industrial Sources/Sterilization RTGs Sr-90 Teletherapy Sources Blood Irradiators Radiography Well Logging Brathytherapy ^ pCi Moisture Density Gauges Nuclear Medicine Diagnostics Smoke Detectors Few Thousands Millions Billions Number of Radioactive Sources in Use Wo;*; nd if approxirmHt! Relative number and strength of radioactive sources Radiography Technologies Photons Entering the Human Body (Penetration&Absorption&Scattering) ■ There are two kinds of interactions through which photons deposit their energy due to interactions with electrons: Penetration Through photoelectric interaction the photon loses all its energy Through Compton interaction photon loses a portion of its energy, and the remaining energy is scattered. Primary radiation Scattered radiation Lead. ■ glasses*'*-. Lead apron Leakage radiation TV monitor eaded glass shiel Image intensiver Jhyroid shieJd ilX* Collimator Skin mR/min 3 R/min X-ray tube 1m ..-0.33 h ■- ■ ■ mR/min .-0.75 mR/min 2m 3m Scattered Radiation Exposure RDDs and REDs Radiological Exposure Device 150 Ciof lridium-192 Source Under Seat Large scale dispersal Properties of Nine Key Radionuclides for RDDs Isotope Half Life [yrs] Spec. Activ. [Ci/g] Decay Mode Alpha [MeV] Beta [MeV] Gamma [MeV] Am-241 430 3,5 a 5,5 0,052 0,033 Cf-252 2,6 540 a 5,9 0,0056 0,0012 Cs-137 30 88 P - 0,19; 0,065 0,60 Co-60 5.3 1100 P - 0,097 2,5 lr-192 0,2/72d 9200 P - 0,22 0,82 Pu-238 88 17 a 5,5 0,011 0,0018 Po-210 0,4/140d 4500 a 5,3 - - Ra-226 1600 1 a 4,8 0,0036 0,0067 Sr-90 29 140 P - 0,20; 0,94 - Response to Radiological Events Absorbed Dose; 0.28 rad/hr Minimize Time Cs-137 Radiation Source Maximize Distance Gamma rays Dose Equivalent: 0.28 rem/hr At this rate, in: •1 hr-Receive avenge annua! Am ■ 19hrs -fleacti occupational annual dose limit for adults of 5 rem I •125 hrs-PottiWy experience mild radiabon medical effects 3 feet away t gram of Cesium-137 10 feet from 20 feet from 30 feet from behind concrete (about the size of a BB source source source Exposure: 0.06 peHet) Exposure: 2.8 Exposure: OJ Exposure: 0.28 Roentoen/br Radioactwity«? Curies Roerrttjen/hr Roentgen/hr Roentgen/hr Minimizing radiation exposure Courtesy RST Inc. Current CB(RN) PPEquipment All fabrics and skin block a-particles Inhaled or ingested a-particles are hazardous Provides Low Energy a and ß-particles protection only Impermeable PPEs are heat sinks and limit operations Protection against x and y-rays is „Zero" and High Energy ß-particles is also negligible Radiation Safety "ALARA" "As Low As Reasonable Achievable" exposure ALARA is a basic requirement of current radiation safety practices. It means that every reasonable effort must be made to keep the dose to workers and the public as far below the required limits as possible. Is to minimize the risk of radioactive exposure or other hazard while keeping in mind that some exposure may be acceptable in order to further the task at hand ALARA have to meet Occupational Dose Limits Occupational Whole Body Total Effective Dose Equivalent 5 rem/yr (0,05 Sv) Dose Limits ■ Recovery and Restoration ■ Rescue operations ■ Saving life ■ Preventing serious injury ■ Actions to prevent the development of catastrophic conditions. ■ In principle, no dose restrictions are recommended if, and ONLY IF, the benefit to others clearly outweighs the rescuer's own risk. ■ Every effort should be made to avoid deterministic effects on health (i.e., effective doses below 100 rem and below 10 times the maximium single year dose limit(50 rem/yr). Radiation Protection ■ Radiation protection, sometimes known as radiological protection, is the science of protecting people and the environment from the harmful effects of ionization radiation, which includes both particle radiation (a, ß±, n°) and high energy electromagnetic radiation (x, y,cosmic-rays). There are four factors that control the amount, or dose of radiation received from a source. Radiation exposure can be managed by a combination of these factors: Amount-Time-Distance-Shielding Three key concepts that apply to all types of ionizina radiation that maximize ALARA TIME DISTANCE SHIELDING Behind nhkdrlmfi from source - loas radiation received 1 Dose = Dose Rate x Time Inverse Square Law E2 = E., [D,/ D2]2 frive#Si Square Law The radiation dose is directly proportional to the time spent in the radiation Sou roe Double the Distance Quarter the Exposure - fif - Radiation Safety ■ Dose Limits ■ Source (amount/energy) ■ Time ■ Distance ■ Shielding ■ Dosimetry Courtesy of Sorenson, 2000 Shielding Shielding against x and y-rays is the Half Value Layer (HVL), the thickness of the material required to reduce radiation to Water or thick slab cf concrete Lead w thick steel pJale Aluminum plate Paper 1/2, HVL = 0.693 Alpha particles Beta particles The Tenth Value Layer (TLV), Gamma rays the thickness required to x rav* reduce the radiation to 1/10 of it's initial value. Z is Atomic Number Percentage Transmission of X-rays through Various Thickness of Lead at Different kVp 60 80 100 120 N120 N250 kVp kVp kVp kVp kVp kVp 0.25 mm Pb 4.28% 11.95 16.73 20.16 30.11 77.52 0.5 mm Pb 0.42 2.55 4.96 6.31 10.05 60.50 1.0 mm Pb 0.01 0.27 0.86 1.09 1.63 37.13 2.0 mm Pb 0.00 0.01 0.05 0.06 0.16 14.20 Shielding The photoelectric effect overwhelmingly dominates energy transfer and absorption; The effectiveness of radiation shielding varies significantly with the photoelectric attenuation coefficients of the constituent materials, the thickness of the garments, and the energy spectrum of the radiation. The purpose of radiation shielding is to protect individuals working with or near x-ray machines and with radioisotopes from harmfully radiation. Personnel shielding is accomplished using 0,25, 0,35 and 0.5 mm lead (Pb) equivalent aprons, thyroid collars, skirts, vests, gauntlets, portable chest shields, glasses, pull-down shields, leaded drapes, etc. A lead apron will reduce your exposure by approximately 95%. For example, if your exposure to radiation is 10mR/hr at a given distance without any shielding, wearing a lead (Pb) apron will reduce this to 0.5 mR/hr. Shielding: Pb apron 0.5 mm stops 99.9% of x-rays at 75 kVp and 75% of 100 kVp x-rays. Personal Radiation Protection Apparel Reproductive organ shields Glasses Aprons, Skirts, Vests Gauntlets Shielding Panels/Walls Lead Aprons in Nuclear Medicine ■ In nuclear medicine, where the energies of the ambient radiation are much higher than in radiography, the lead apron is of limited use, and is often considered too restrictive for day long wear. ■ A 0.25 mm lead apron will provide a dose reduction of about only 40% for low energy gamma emitter Tc-99m (140 keV). A 0.5 mm lead apron weighs about 12 kgs and will provide a dose reduction of about 70%; ■ Lead apron is less effective in reducing radiation levels from a mixed beta and gamma emitter such as 1-131, (360 keV) 52.6%; and ■ Lead apron is not very effective in reducing radiation exposures from a high energy gamma emitter such as F-18, (511 keV) 18.2% ■ Lead apron for a pure beta emitter such as Y-90, is more effective 99.8%; Syeda Ahmed, et all.;J Nucl Med. 2007; 48 (Supplement 2):470P Lead Protective Materials Lead and lead composites are the most common shielding materials used to protect against X-rays and y-rays; Radiation shielding aprons and coverings have been manufactured from lead Pb or PbO (~ 40%) powder-loaded polymer or elastomer sheets (vinyl, PVC, butyl orstyrene butadiene rubber); Typical garment lifetime for these materials is approximately 10 years, However aging, damage, embrittlement as well as cracking, can drastically shorten this period of lifetimes. Atypical Pb-based radiation shielding garment may contain approximately 0.5 m2 of shielding material with a thickness of 1.5 mm, with a mass of about 4.5 kg. This is for 58 % heavier as a garment composed of 0.5 mm pure Pb, with the same protection (approx. 2.6 kg per 0.5 m2). Those who wore aprons with weight of 6-7 kgs for more than 10 hours a week missed more time from work owing to back pain. Defects in Lead Protective Aprons No defects Bunching caused by folding I 1 !jf i t Radiology 1982, 152; pp.217-218 Low density strip defect Peppering of small holes Lead Apparel-Concerns ■ Weight ■ Embrittlement ■ Mechanical sensitivity ■ Microsized fillers ■ Aging ■ Attenuation limits ■ Lead is toxic ■ Disposal ght Apparel ■ -30% lighter ■ Reduced lead content ■ Non-lead composite ■ Nano-sized fillers ■ Attenuation improvement ■ Mechanical improvement ■ Thermo conductivity ■ Whole body apparel ■ CBRN protection ■ Recycling Elements incorporated into some commercial radiation-shielding garment materials ELEMENT ATOMIC NO. DensiLy (g/cm3) K absorption e Cadmium (Cd) 48 8.65 Indium (In) 49 7.31 27.9 Tin (Sn) 50 730 29.2 Antimony (Sb) 51 6.69 30.5 Cesium (Cs) 55 1.87 36.0 Barium (Ba) 56 3.5 37.4 Cerium (Ce) 5E 6.66 40.4 Gadolinium (Gd) 64 7.90 50.2 Tungsten (W) 74 19.3 69.5 Lead (Pb) 82 11.36 8B.G Bismuth (Bi) 83 9.75 90.5 McCaffrey etal.Meó. Phys. 34 ,(2) February 2007 ??? ZERO Protection ??? Radiation Interaction with Mass Incident Photon in» Incident Photon Incident Photon Incident Photon Photoelectric absorption of x-rays occurs when the x-ray photon is absorbed, resulting in the ejection of electrons from the outer shell of the atom, and its ionization. Photoelectron absorption is dominant for atoms of high atomic numbers and attenuation coefficient \i value is proportional to atomic number ji &Z3 Compton scattering occurs when the incident x-ray photon is deflected from its original path by an interaction with an electron. The scattered x-ray photon loses energy due to the interaction but continues to travel through the material along an altered path. Pair production can occur when the x-ray photon energy is greater than 1.02 MeV, but really only becomes significant at energies around 10 MeV. Thomson scattering, also known as Rayleigh, coherent, or classical scattering, occurs when the x-ray photon interacts with the whole atom. Gamma and X-rays Attenuation Gamma (y) and X-rays radiation consists of highly energetic photons with high frequency. They can be stopped by a sufficiently thick layer of material with high atomic number "Z", such as Lead (Pb-82) or depleted Uranium (U-92). ■ Photoelectric Effect of attenuation coefficient u is proportional to atomic number "Z" ■ E.g. Pb aprons (Z = 82) absorbs y and X-rays ~ 1,000 more rather than soft tissue with approx. Z ~ 8 Attenuation |j( total) = p(photoelectric) + (j(Compton) Incident X-ray Photons I FKT^tia I .■">. r r I ■ n l I r*l a n Wlrh LJi-i-.Tiit I-Trarve-led iri [hs Amouns of AttenuaAed A Ii e cling Amount of Transmission Phöwn MaT^pijI Oe-n-5-llY A[orrnt Mum rrartimi(te > .»s .vy .t ^ Radio/Nuclear (Chem/Bio) Inner fabric Skin contact Absorption and deflection of Rays ■ Different shape of nano-particles Nn-Particles Nn-Platelets Nn-Tubes Nn-Hollow Spheres Shielding composite with nano-particles radiation Shielding layer with nano-size particles True CBRN Protective Ensemble Courtesy RST Inc. 0,400 0,350 0,300 j OÍOO j 0A50 I ojdo 0100 Attenuation Ratio Fver$usVoltag*atRTG ♦ * ■ + 1 ■ * • 0 ^ * X ♦ Demroii L Layer ■ Demron i Layer? Demron 3 Layers Derm ion 4 Layers Demron 5 Layers t Apran 0,25 Pb 0 Apron 0,35 Pb -Apren 0,5 Pb 20 40 lStog*atHTQ8tíj[kV] 100 120 140 110% 105% 100% 95% [»% ■ 85% 80% 75% 70% 65% 60% Attenuation F versus Voltage of RTG 20 40 60 80 100 voibptat m u[W] 120 + DemiůJi 1 Luv'e ľ Denrnon 2 Layers Demron 3 Layers a Demron 4 Layers ' Demron 5 Layer? • Apron 0,25 Pb O Apron 0,35 Pb ^—Apron 0,5 Pb 140 Normalized Ration of Attenuation F (0,5 Pb Apron) versus Voltage at RTG 2,500 1,500 I I I "SljOOO 0,500 OjOQO Voltage at RTG U [kV] x O 20 40 60 1 0 80 0 100 * -I— 120 ♦ Demron 1 Layer ■ Demrori 2 Layer; Demrori 3 Layers a Demron 4 Layers ■ Demron S Layers • Apron 0,25 Pb 0 Apron 0,35 Pb —Apron 0r5 Pb 140 Cs-137 (ß)512 keV and (y)662 keV Dose Rate and Attenuation Ratio of DEM RON Shielding with Cs -137 ItemsofDose Rate and Attenuation Ratio Measurement ■ During the measurement background dose rate fluctuated between 0,04-0,05 uGy/h and Cs-137 source gave dose rate of 0,552 uGy/h. Folding of DEMRON layers provide synergy effect in increasing of attenuation rate. 4 layers of DEMRON are surprisingly equivalent to 2 mm of Pb. Sample of multiply DEMRON layers as RDD shield provide effective attenuation of 79% against Cs-137 source. Only True CBRN Anti-Radiological and Anti-Nuclear Protective Ensemble ■ CBRN Full Body Suit ■ High Energy Nuclear/Ballistic Shield (IED, RDD, RED) ■ Anti Ballistic/Nuclear Vest ■ Anti Nuclear Blanket ■ Radiological/HazMat Bags ■ Casualty Bag Shieldina of radiation source Chem/Bio and Chem/Bio/Rad Improving Radiation Protection Use Shielding 1 ft concrete RDD Blankets and Shields Maximize Distance Minimize Time Absorbed Dose: 0.028 rad/hr Dose Equivalent 0.28 rem/hr At this rate,In; iohr§' Receive «v*nge annual dose 190 hrj - Reach occupational annual dose I imrt for adults of 5 rem 1150 hrt-POBitty experience mHd radiation medical effects 3reet«way 1 gram of Cesium-137 lOfeetfrom 20 feet from 30 feet from behind concrete (about the size of a M source .028 source 0.07 source 0.02a Exposure: 006 pellet) Exposure: Exposure: Exposure: Roentgen/hr Radioactivity 87 Curies Roentgen/hr Roentgen/hr Roentgen/hr ssv RST Inc Minimizing radiation exposure Thank you for your Attention Pavel CASTULIK pcastulik&vahoo. co. uk Radiation Events 26 April 1986 at 1:23 a.m. the Nuclear reactor No. 4 was destroyed by two explosions Steam explosion and following fire of graphite, disseminate aprox, 5% of radiation material during 10 days Serious contamination of 200,000 km2 with Cs-135 That happened with devastating results in Goiania, Brazil, in 1987, when scavengers dismantled a metal canister from a radiotherapy machine at an abandoned cancer clinic. The Caesium-137 teletherapy unit became totally insecure. Soon afterward, a junkyard worker pried open the lead canister and discovered a pretty blue, glowing dust: radioactive Cesium-137. In the following days, scores of people were exposed to the substance - some parents painted their children with it and sold tickets to neighbors to watch them dance. As a result, 112,000 people had to be monitored. Of those, 249 were contaminated; 28 suffered radiation burns and 4 people died. More than 67 square kilometers was monitored, large areas had to be decontaminated and 3,500 cubic meters of radioactive waste was generated. For years afterward, the region was stigmatized and its economy devastated . RwJiition hnd Ol ! fttdl11lot* aperiurt E E LL TfrtflifindErtrThickfeit'l nun -- Windowdiairirtcr 30.1 mm — Eöu'w nwtanaJ dniiWKr 36,3 -| --1 CaPM*l*dl#met*r50£ipni — Fl«l 1B&I Wödi'iEd fittina tar »tTieluiifiit k Wifling liftttmation»! tfljiulcl .s-j nlris nt*IS («Birilfi! iieeI) Säuret Tiarensl DwiütY- 3000 ^n1 Speorfifi |C|ivil\ b14 " iq/i j TeitfietmiY (1S71) 74TBfl ■ Mass 12 kg September 2007 ■ Dose rate on surface: 11 uSv/h ■ Specific Activity: 232Th - 45 kBq/kg ■ Specific Activity: 226Ra - 20 kBq/kg ■ Cs-137 0,6 Ci December 2006 137 Cs 3.0 Ci October 2003 137 Cs 0.7 Ci August 2003 ä. i U02 335 pellets, total weight 1628.5 g Uranium content 1435.5 g 235U enrichment level 4,42 % 235U isotope weight 63.4 g 730^-0 1 -|750S>-01-T