Week 5 Radiation

Ionizing Radiation 

• has the ability to displace an electron from an atom or a molecule,

  • producing ions in the process.

• Sources can be 

  • cosmic rays

  • X-ray machines.

• These rays have higher frequency but shorter wavelength.

• can affect the atoms in living things, so it poses a health risk by damaging tissue and DNA in genes

• types of ionizing radiations are

  • Alpha particles

  • Beta particles

  • Gamma rays 

  • X-rays

frequency, f

is the number of waves passing a point in a certain time.

per one second, gives the unit hertz (Hz)

The wavelength, λ

a wave is the distance from any point on one wave to the same point on the next wave along.

measured in metres (m)

Alpha particles

• are emitted from atoms of radioactive materials during radioactive decay

Beta particles

• are emitted from atoms of radioactive materials during radioactive decay

• are more penetrating than alpha particles

• less damaging to living tissue and DNA

  • the ionizations they produce are more widely spaced

Gamma rays (γ)

• are weightless packets of energy called photons.

• are similar to visible light, but have much higher energy

• are often emitted along with alpha or beta particles during radioactive decay.

• X-raysare a hazard to the entire body. 

X-rays

• are also photons of pure energy

• X-rays and gamma rays have the same basic properties but come from different parts of the atom.

• X-rays are generally lower in energy

  • therefore, less penetrating than gamma rays.

Order of ionizing ray penetration

1. gamma rays and X-rays

2. beta 𝛽  particles

3. alpha 𝛼 particles  

Non-Ionizing Radiation

• do not carry enough energy to ionize atoms or molecules.

• examples

  • Radiation from sun

  • light bulbs

  • electric power lines

  • radio

  • TV antenna

  • lasers

• Three major types of non-ionizing radiation found in laboratories

  • lasers

  • microwaves

  • ultraviolet radiations.

Laser

• monochromatic

  • contains one specific wavelength of light (one specific color).

• Laser beams are very narrow and focused with the outcome being a large amount of energy focused onto a small target

• Laser radiation can be generated in different parts of the spectrum

  • ultraviolet (UV)

  • visible light

  • infrared (IR).

• It can cause Instant injury to

  • cornea

  • retinal

  • cause skin burn.

• must always follow the proper precautions when handling Lasers.

Examples of laser usage: 

• Eye surgery (surgical lasers)

• CD players 

• Medical and laboratory instruments 

• Tattoo removal 

• Hair replacement

LASER is an acronym for

Light

Amplification by

Stimulated

Emission of

Radiation.

Laser Hazards

• eye injury because the cornea and lens of the eye can focus these parallel light beams and burn the retina

• fire (lasers for surgery or cutting processes)

Hazard Controls

• Install and certify/re-certify lasers according to manufacturer’s recommendations.

• Limit access, especially during use.

• Operate lasers of Class IIIB and above only in posted laser-controlled areas.

• Use shielding.

• Avoid direct viewing of the laser.

• Avoid reflections from objects (mirrors, walls).

• Wear eye protection appropriate for the laser type and energy.

Classes of Lasers: Type 1

• Enclosed beam or low power

  • Unlikely to cause eye injury

  • Examples 

    • Compact disc players

    • laser printers

    • bar code scanners

Classes of Lasers Type 2

Low power lasers (<1 milliwatt)

• Staring into beam could damage eyes

• examples 

  • Classroom pointers

  • some surveying leveling equipment

Classes of Lasers: Type 3A

• 1 to 5 milliwatts power

• Staring into the beam or through lenses hazardous to

  the eyes

  • example

    • some pointers

    • some surveying leveling equipment

    • therapeutic lasers (for localized heating of tissue)

Classes of Lasers: Type 3B

• 5 to 500 milliwatts power

• Instant injury to the eyes

• from direct or specularly reflected beam

  • Examples 

    • Lasers for light shows

    • lasers for engraving labels

    • certain medical lasers

Classes of Lasers: Type 4

• Greater than 500 milliwatts power

• Instant injury to the eyes or skin

• from direct, specularly reflected or diffuse scattered beam

• Can cause fires

  • example

    • surgical lasers

    • computer controlled cutting lasers

Microwaves

work partially due to heating.

The following are the guidelines for proper use of microwaves:

• Make sure doors hinges are sealed tight 

• Check oven for leaks 

• Do not use metal 

• Place the object to be heated in the centre

• When using high powered microwaves

  • ensure shields and protective covering are in place

  • post warning signs to protect people wearing pace makers

    • electromagnetic waves may interfere with the device’s pulse generator and can permanently damage it.

• Common home use microwaves are considered to be of low risk

  • however, it is better to be at a distance of at least six inches away from the equipment.

Microwaves Hazards

principal hazard associated with microwave use

• is heating of tissue

• Overheating and overuse can also result in fires.

Hazard controls

• Choose microwave ovens that are approved for commercial not domestic use.

• Perform regular maintenance (e.g., ensure door hinges are secured and door seals are tight).

• Avoid heating screw-capped or any tightly closed containers in a microwave.
  

  High-powered microwave and radio wave devices require additional controls:

• Ensure shields and protective covers are in place during operation.

• Post warning signs to protect people wearing pacemakers.

Ultra Violet Radiations

• consist of lamps having wavelengths between 180 to 390 nm (nanometer).

• commonly used wavelength is 254nm.

• mainly used as a sterilizing agent.

• As UV radiation has a very low energy

  • it has a very low penetration power

  • can penetrate not more than 1 cm

  • cannot penetrate through opaque surfaces

  • it is mostly used for surface treatment.

Sunlight is made up of three kinds of UV radiations

• UV-A (Alpha)

• UV-B (Beta)

• UV-C. 

UV radiation Hazards

• Pain and injury may result from overexposure to UV.

• This may be particularly acute in the eye

  • can cause conjunctivitis

  • photosensitivity

  • loss of vision.

UV radiation may be reflected by some surfaces, such as stainless steel

Hazard controls:

• Use goggles or full-face shield with lens filters.

• Cover exposed body parts

• Turn off UV lights after use.

UV-Alpha (A)

• falls between the wavelengths of 323-360 nm

• is not readily absorbed by the human skin

• generally used in tanning machines

UV-Beta (B)

• falls between the wavelengths of 230-320 nm

• is the most lethal as this is the optimal absorption wavelength for DNA of the cells.

• Too much exposure to UV-B causes

  • sunburn

  • wrinkled/aged skin.

USED IN LABS

UV-C

• falls between the wavelengths 100-280 nm

• this radiation is absorbed by the atmosphere

  • does not reach the earth.

U. V as a sterilizing agent

• causes modification or break in DNA

  • which in turn causes death of the organism.

• It is used to sterilize and decontamination of hospital

  • operating rooms

  • food processing areas

  • infected waste stations.

• It is also used in the sterilization of the work area of bio safety cabinets.

Radiation Hazard

Exposures to radiation, specifically ionizing radiation, can be external and internal.

• eternal exposures

  • radiation can penetrate deeply into human body through the skin.

• Internal exposure to any radioactive nuclear material can

  • inhalation

  • ingestion

  • through eyes, or cuts.

Effects of radiation can be

• acute (Immediate)

• chronic (appearing years after exposure).

Body parts at greatest risks are:

• Blood forming cells 

• Breasts

• Thyroid 

• Lungs

Examples of acute effects

(i.e., large dose over a short period)

• skin

• bone marrow

• digestive system

• neuromuscular system

such as

• Skin sunburns

• Aplastic anemia (bone marrow stops producing enough new blood cells)

• Loss of appetite

• Fatigue 

• Nausea 

• Vomiting 

• Diarrhea 

• Fever

Examples of chronic effects 

• leukemia

• other malignancies

• Leukemia 

• Other malignancies 

• Premature skin aging 

• Skin cancer 

• Weakening of the immune system

• Eye problems like cataract

Safety Procedures for Handling Radioactive Materials

• Know the proper shielding requirement for material presenting external radiation hazard and use the appropriate shielding like

  • Bench top Plexiglass shield

  • Face shield

  • PPE like gloves 

• Avoid direct contact to the eyes and skin

• Use a Fume Hood for any work involving

  • dry powders

  • volatile material 

• Be aware of all dangerous properties of the radioactive material

  • store and handle accordingly.

• Minimize the radiation dose

  • maximize the distance between

    • the radiation source and people. 

• Radioactive signs should be posted on all doors to rooms where radioactive material are used or stored.  

International System of Units (SI) for absorbed dose

• for radiation measurement 

• the official system of measurement

• uses the "gray" (Gy) as a unit for the absorbed dose

• potential damage from an absorbed dose depends

  • type of radiation

  • the sensitivity of different tissues and organs

Sievert" (Sv) or Rads

• The SI unit for the effective dose

• The effective dose is used to measure ionizing radiation in terms of the potential for causing harm.

• The Sv takes into account

  • the type of radiation

  • sensitivity of tissues and organs.

Units for Radiation Activity

• Curies (CI)

• Becquerels (Bq)

Exposure Units

• Roentgens (ren)

dosimeter

equipment used to monitor radiation

Thermoluminescent Dosimeter (TLD) Badge

is a type of radiation dosimeter.

• It can monitor the

  • whole body

  • upper extremities (hands, fingers, wrists and forearms)

  • lower extremities (feet, ankles and lower legs). 

• are used to monitor radiation exposure.

• The two most common types of TLDs are 

  • calcium fluoride 

  • lithium fluoride

Guidelines for Minor Radioactive Spills 

• Notify all in the immediate area and limit access to those cleaning up the spill 

• Cover spill with absorbent paper. Never apply paper to flammable or corrosive material 

• Survey staff with radiation monitor before they leave the area 

• Remove contaminated clothing and footwear and wash affected area with soap and water 

• Dispose of clean-up material in a labelled container according to institutions policy and procedure 

• Notify radiation safety officer

Guidelines for Major Radioactive Spills

• Notify all in the immediate area and limit access to those cleaning up the spill 

• Turn off any ignition source

• Vacate room, close door and post warning sign

• Contact radiation safety officer

• Qualified personnel will select the appropriate PPE, refer to SDS and all reference and supplies 

• Survey staff with radiation monitor before they leave the area

• Remove contaminated clothing and footwear and wash affected area with soap and water 

• If contamination persists, use diluted potassium permanganate or 3-5% EDTA (Ethylene diamine tetraacetic acid) 

• Dispose of clean-up material in a labelled container with the radioactive symbol and according to institutions policy and procedure.

Government Legislation and Licensing

• All radioactive nuclear substances must be handled and disposed of in accordance with the conditions instituted by the Canadian Nuclear Safety Commission (CNSC).

  • acquisition, possession, use and disposal of nuclear materials

  • is regulated and monitored by them

• a federal regulatory agency with responsibility for radiation safety

• ensures that the use of nuclear substances does not pose undue risk to

  • health

  • safety and security of the public,

  • environment.

• The CNSC recommends dose limits for those working with radiation.

Ionizing Radiation (CLMLS definition)

is a form of radiation that can displace an electron from an atom or a molecule, thereby producing ions.

sources

• X-rays

• gamma rays

• alpha particles

• beta particles

• neutrons

CLMLS

External exposures (radiation)

are of concern when dealing with radiation that can penetrate deeply into the human body.

Highly penetrating radiation types include:

• X-rays

• gamma rays

• high-energy beta particles, which can produce X-rays in collision with metal, and which,

• if exposed to the eyes or in direct contact with the skin, present an external exposure hazard

Internal exposures (radiation)

Internal exposures occur when a nuclear material is:

• inhaled

• ingested

• absorbed through the skin or eyes, or via cuts or abrasions

hazards include:

• alpha particles (these are the most damaging to human tissue when absorbed)

• beta particles

• gamma emitters

Organs at greater risk to radiation

• blood-forming cells (e.g., bone marrow)

• breasts

• thyroid

• lungs

• digestive system

• a fetus is also highly sensitive to radiation

Canadian Nuclear Safety Commission requirements for the use of radiation

• a license

• dose monitoring and dose limits

• possession limits

• wipe testing for laboratory surface contamination

• inventory tracking and record-keeping

• security

• training

Radionuclide Information Booklet

• The Canadian Nuclear Safety Commission publishes a Radionuclide Information Booklet provides “information on various nuclear substances”

  • radiation characteristics

  • detection methods

  • preventive measures

  • annual limits on intake

• Refer to the most recent publication for specific information

Ionizing Radiation Hazard Control

Time, Distance and Shielding are the hazard control principles used to reduce exposure: 

• Demarcate “hot” (radioactive) work areas by using radiation warning signs and tape.

• Identify all hazards of radioactive materials (flammability, chemical toxicity, corrosivity, volatility, etc.), not just the radiation-emitting properties.

• Minimize exposure by practising techniques without radioactive material. Handling proficiency tends to minimize time of exposure and surface contamination.

• Maximize the distance between radiation sources and employees.

• Wear dosimeters.

• Use effective shielding (e.g., Plexiglas) and protective equipment (e.g., gloves).

• Use shielded storage where appropriate.

• Perform surface contamination checks (e.g., wipe tests) and decontaminate as required.

• Use disposable absorbent liners on trays or work surfaces.

• Monitor incoming shipments of radioactive materials for leakage