Unexpected Radiation Exposure Scenarios Timur Durrani, MD, MPH, MBA - - PDF document

Unexpected Radiation Exposure Scenarios

Timur Durrani, MD, MPH, MBA Associate Professor of Medicine, UCSF Site Occupational Medical Director, LBNL March 7, 2020

Outline

• The Advanced Light Source (ALS)
• Expected radiation exposure scenarios
• Review of types of radiation
• Overview of radiation assessment
• Examples of radiation injury and treatment
• Unexpected radiation exposure scenarios

The Advanced Light Source (ALS)

A specialized particle accelerator that generates bright beams of x-ray light for scientific research. Electron bunches travel at nearly the speed of light in a circular path, emitting ultraviolet and x-ray light in the process. The light is directed through about 40 beamlines to numerous experimental end stations, where scientists can conduct research in a wide variety of fields, including materials science, biology, chemistry, physics, and the environmental sciences. The wavelengths of the synchrotron light span the electromagnetic spectrum from infrared to x-rays and have just the right size and energy range for examining the atomic and electronic structure of matter.

ALS Beamlines The Electromagnetic Spectrum

Annual outdoor effective dose from cosmic radiation for North America, 2004

Metals in Earth’s crust

Abundance (atom fraction) of the chemical elements in Earth’s upper continental crust as a function of atomic number.

Ionizing Radiation Exposure to the Public

The atom Radioactive Decay

How x-rays work Types of Ionizing Radiation

Alpha – concern for internal contamination (i.e. Radon) Beta – concern for internal and external contamination Gamma – like X-rays, but emitted from nucleus, X-ray emitted from electrons. Concern for internal contamination. Neutrons – uncharged particles from the nucleus. More potent than Gamma Rays. Have the ability to make something else radioactive.

Ionizing Radiation

α β γ neutron Paper Plastic Lead Concrete

Periodic Table Categories of Isotopes

University Five 14C, 32P, 125I, 131I, 252Cf Industrial three: 192IR, 137Cs, 60Co Military five: 3H, 235U, 238U, 239Pu, 241Am Fission/Activation products:

• Iodine
• Strontium
• Cesium
• Uranium
• Plutonium

How Fission works

Large atom (Plutonium) bombarded with neutrons, causes the atom to split (fission) in uneven products Plutonium (235) = Strontium (87) + Cesium (132) + Neutrons The core of a fission bomb is either plutonium or highly enriched uranium. These are the only materials that can achieve a self- sustaining chain reaction.

Example Chain reaction Fission Yield of U-233, U-235, P-239

Atomic Mass Fission Yield %

Types of Fission Materials

Uranium – 235 (comes out of the ground)

• 5% used in reactors
• 20% used in weapons

Plutonium (comes out of a lab)

Units

Curie (Ci) basic unit of radioactivity in US Dose refers to the absorption of radiation energy per unit mass of absorber. The conventional (USA) dose unit is the rad. The SI dose is the Gray.

• 1 Gy = 100 rad

Annual Regulatory Limits (US NRC)

Non-Occupational rem ~Gray Members of the Public 0.1 0.001 Occupational Whole Body (internal + external) 5 0.05 Any individual organ 50 0.5 Lens of the Eye 15 0.15 Skin 50 0.5 Extremities 50 0.5 Fetal Dose (declared pregnancy) 0.5 0.005

How this works practically

Source is determined to be α,β, or γ using the Geiger Counter Geiger Counter takes initial measurement (in counts per minute). This gets converted to Rad/Rem and compared to the Annual Regulatory Limits to determine if it is a medical/regulatory problem

Medical Testing

Example Andrews Lymphocyte Nomogram Nasal Swab CBC w/diff Dicentromere cytogenetics Bioassays (urine/feces).

• Ed. CHAPTER 142 Radiation Emergencies

• Radiation. International Atomic Energy

Radiation exposure is toxic exposure

Radiation is toxicity by energy Mechanism of action: breaks chemical bonds in DNA, produces ions and free radicals Dose estimation: depends on type of agent, activity of agent, and exposure Exposure is dependent on duration of exposure (time) proximity of exposure (distance) and protection (shielding)

Radiation injury appears depending on dose

Higher doses cause injury sooner (days) than lower doses (weeks).

– Immediate: Redness, swelling, blisters, ulceration,

tissue necrosis

– Delayed: Fibrosis, atrophy (sclerosis), and

telangiectasia formation, cancer

Acute Radiation Syndromes

Dose (Gray) Syndrome Effects 1-2 Hematopoietic ~100% Survival without treatment 3-5 Gastrointestinal LD50/60 without treatment 6-8 LD50/60 with supportive care 9-10 Consider Stem Cell transplant 10+ Neurovascular Multiple Organ failure, probable death LD50/60 - 50% death of exposed in 60 days

Cutaneous Radiation Injury

Dose (Gray) Injury Onset 3 Epilation (hairloss) 14 – 21 days 6 Erythema Waxes/Wains, early as few hours to 14 – 21 days 10 – 15 Dry desquamation 20 days 15 – 25 Wet desquamation 14 – 21 days

Exposure scenarios Electron Accelerator Accident

INTERNATIONAL ATOMIC ENERGY AGENCY, An Electron Accelerator Accident in Hanoi, Viet Nam, , IAEA, Vienna (1996).

Diagram of accelerator facilities and

• ffices

Diagram of the microtron accelerator Diagram of exposure position

Local Injury

Day 28

Day 14

Ongoing

Day 113

Estimated dose to right hand

Uncontrolled medical therapy source, Cs137

INTERNATIONAL ATOMIC ENERGY AGENCY, The Radiological Accident in Goiania, IAEA, Vienna (1988).

Abandoned Radiotherapy Clinic Radiation Therapy Schematic

Cesium Chloride

Luminescent CsCl Source Capsule

The Human Toll

• 249 people were contaminated.
• 20 people were admitted to the hospital.
• 4 of the casualties died within four weeks of their

admission to hospital.

• The post-mortem examinations showed hemorrhagic

and septic complications associated with the acute radiation syndrome.

• The best independent estimates of the total body

radiation doses of these four people, by cytogenetic analysis, ranged from 4.5 Gy to over 6 Gy.

Uncontrolled Industrial radiography source, Ir192

INTERNATIONAL ATOMIC ENERGY AGENCY, The Radiological Accident in Yanango, , IAEA, Vienna (2000).

Industrial Radiography

Industrial radiography is used throughout the world to examine the structural integrity of materials in a non- destructive manner.

Housing Container ‘Camera’ Ir192 ‘Pigtail’

The incident

Day 2

• The source became detached

from the ‘camera’.

• At 4pm, a welder picked up the

unshielded source with his right hand and placed it in the back right pocket of his trousers

• At 9pm he felt a pain in the back
• f his right thigh.
• At 10:30pm he complained to his

wife about the pain and she looked at his posterior right thigh and noted a red area of skin.

The incident continued

He took off his jeans and, with the source still in the pocket, placed them on the floor. He visited a local doctor who told him he had an "insect bite" and that he should put a hot compress on the area. The welder's wife meanwhile spent about five to ten minutes squatting/sitting on his jeans while she breastfed their 18 month old child. T Two other children who were at home, a girl of ten and a boy of seven, were about two to three meters from the source for approximately two hours.

Imaging

Day 6: Scout CT Day 6 MR

Day 23 Day 297

Family

• The patient's wife showed

moist desquamation, ulcerative and fibrotic lesions in the lower back after her brief exposure to the source while sitting on her husband’s jeans

• No hematological changes

were observed in her or her children. Day 240: Ulcerative lesion on the lower back of the patient's

• wife. Day

Could this happen here? Resources

IAEA website – accidents and exposures

• https://www.iaea.org/publications/8117/the-radiological-

accident-in-nueva-aldea

• Report No. 161 II - Management of Persons

Contaminated With Radionuclides: Scientific and Technical Bases (2008)

• NRC Event notification: https://www.nrc.gov/reading-

rm/doc-collections/event-status/

Backup Slides ALS Safety

The ALS is a 3rd generation synchrotron light source and is designed to produce very powerful beams of ionizing radiation. For accelerators such as the ALS, the most important (safety) components are shielding and interlocks. The Radiation Safety System (RSS) controls shutters which allow photon radiation into the beamlines. For personnel safety, these shutters are interlocked to ensure that no one can be exposed to the radiation. Accelerator shielding consists mainly of (permanent) concrete blocks.

ALS Beamlines

Radiation Safety Systems

Interlock System Beamline shielding

Shielding (cont'd.)

Also includes beamline components that contain vacuum envelope such as bellows, ion pumps, piping, etc.

What is the single largest source of ionizing radiation exposure in to the public?

A) Radon B) Cosmic C) Medical x-rays D) Occupational

Basic ionizing radiation control measures include which of the following:

A)Minimize time of exposure B)Increase distance C)Use shielding D)All of the above

Effects of acute radiation exposure on the central nervous system can be observed at doses of:

A)10 Gray B)5 Gray C)2.5 Gray D)1.25 Gray