1. Analytical X-ray Diffraction Safety Training Part I
Slides developed by John Pickering SJSU Radiation Safety Officer (RSO)
(Retired)

2. What is the purpose of radiation safety training?
To help you gain enough knowledge to enable you to perform your job safely. To ensure that you adhere to proper radiation protection practices while working with or around x-ray generating devices.

3. Fundamental Radiation Physics
Radiation – alpha particles, beta particles, gamma rays, X-rays
Radioactivity – spontaneous nuclear transformations
Generally alpha particles and beta particles
Often accompanied by gamma ray emission
Ionizing Radiation – radiation capable of producing charged particles (ions) in the material through which it passes

4. Radiation is energy in transit
in the form of high speed particles and electromagnetic waves.
We encounter electromagnetic waves every day. They make up our visible light, radio and television waves, ultra violet (UV), and microwaves with a spectrum of energies.
These examples of electromagnetic waves do not cause ionization of atoms because they do not carry enough energy to remove electrons from atoms.

6. Ionizing radiation
Ionizing radiation is radiation with enough energy so that during an interaction with an atom, it can remove tightly bound electrons from their orbits, causing the atom to become charged or ionized.
Ionizing radiation deposits energy at the molecular level, causing chemical changes which lead to biological changes. These include cell death, cell transformation, and damage which cells cannot repair. Effects are not due to heating.

7. Radiation Units
Roentgen (R) The roentgen (R) is a unit of radiation exposure in air.
It is defined as the amount of x-ray or g radiation that will generate 2.58E-4 coulombs/kg of air at standard temp and pressure.
rad RAD stands for Radiation Absorbed Dose and is the amount of radiation that will deposit 0.01 J/kg of material.
A roentgen in air can be approximated by 0.87 rad in air, 0.93 rad in tissue, and 0.97 rad in bone.
Dose
The SI unit of absorbed dose is the gray (Gy), which has the units of J/kg. 1 Gy= 100 rad.

8. Radiation Units
REM REM stands for Roentgen Equivalent Man. The REM is a unit of absorbed dose and is equal to the rad multiplied by a weighting factor which varies according to the type of radiation. The weighting factor for x-rays is equal to 1.
For x-rays, one rem is equal to one rad.
The SI unit used in place of the rem is the sievert (Sv). 1 Sv = 100 rem.

9. Radiological Fundamentals
The basic unit of matter is the atom.
Nucleus
Electron
The basic unit of matter is the atom.
The central portion of the atom is the nucleus.
Electrons orbit the nucleus.
The nucleus consists of protons and neutrons.
Nucleus
Protons
Neutrons

11. X-RAY AND GAMMA ( ) RAY PROPERTIES
Charge: None
Mass: None
Velocity: 3 x 108 m/s
Origin:
Rays: Nucleus
X Rays: Electron Cloud & Bremsstrahlung

12. What are x-rays?
X-rays are photons (electromagnetic radiation) which originate in the energy shells of an atom, as opposed to gamma rays, which are produced in the nucleus of an atom.

13. Ionizing Radiation

14. Four principal kinds of ionizing radiation
Atomic
Mass
Electrical Charge
Range in Air
Range in Body Tissue
Attenuation
Exposure Hazard
Alpha (He nuclei) 4 +2
< inch
Unable to penetrate skin
Stopped by a sheet of paper or skin
Internal
Beta
(electrons or positrons)
1/1840 -1
Several feet
1/3 inch
Stopped by a thin sheet of aluminum
Skin, eyes, and internal
Gamma / x-ray
(photons)
None
Passes through
Thick lead or steel
External and internal
Neutron 1
Neutral
Hundreds of feet
About 10% goes through
Several feet of water or plastic
Primarily external

15. Background Radiation Cosmic - 28 mrem Radon - 200 mrem Diet - 40 mrem
Terrestrial - 28 mrem

16. Man-made Radiation Man-made sources of radiation contribute to
the annual radiation dose (mrem/yr).
Cigarette smoking
Medical - 53
Round trip US by air
5 mrem per trip
Building materials - 3.6
Gas range - 0.2
Smoke detectors
Fallout < 1

17. Radiation Sources
X-ray diffraction is a source of very intense radiation.
The primary beam can deliver as much as 400,000 R/minute
Collimated and filtered beams can produce about 5,000 to 50,000 R/minute
Diffracted beams can be as high as 80 R/hour

18. Dose Limits EPA Guidance for dose limits
NRC Regulations for dose limits
DOE Regulations for dose limits
DOT Regulations for transport
State Agreement States
NCRP National Scientific Body
Licensee Institutional Admin Limits

19. Regulatory Limits Radiation Worker Whole Body Extremities
Skin and other organs
Lens of the eye
Non-Radiation Worker
Embryo/fetus
Visitors and Public
5 rem/year - 3 rem/quarter
50 rem/year
15 rem/year
0.5 rem/year
0.5 rem/gestation period
0.1 rem/year

20. ALARA Program As Low As Reasonably Achievable
Responsibility of all employees
Exposures shall be maintained ALARA
Below regulatory limits
No exposure without commensurate benefit

21. Responsibilities for ALARA
Ultimately YOU are!
Responsibilities for ALARA
To establish a program
Meet regulatory limits
Management
Safety Organization
Implementing a program
Run the daily operation
Radiation Worker
To follow program

22. General Methods of Protection
Time
Distance
Time
Minimize the time around the x-ray source. Less time equals less exposure.
Distance
Increase the distance. Radiation reduces by 1/(distance)2
Shielding
Put appropriate material between you and the source.
Shielding

23. What are x-rays?
X-rays are produced when accelerated electrons interact with a target, usually a metal absorber, or with a crystalline structure. This method of x-ray production is known as bremsstrahlung.
The bremsstrahlung produced is proportional to the square of the energy of the accelerated electrons used to produce it, and is also proportional to the atomic number (Z) of the target (absorber).

24. What are x-rays?
Many different types of machines produce x-rays, either intentionally or inadvertently. Some devices that can produce x-rays are x-ray diffractometers, electron microscopes, and x-ray photoelectron spectrometers.
X-rays can also be produced by the attenuation of beta particles emitted from radionuclides.

25. How X-rays are Produced
When fast-moving electrons slam into a metal object, x-rays are produced. The kinetic energy of the electron is transformed into electromagnetic energy.
X-ray Tube

26. What are X-rays Electromagnetic radiation
Originate in energy shells of atom
Produced when electrons interact with a target
target
X-rays are photons (electromagnetic radiation) which originate in the energy shells of an atom, as opposed to gamma rays, which are produced in the nucleus of an atom.
X-rays are produced when accelerated electrons interact with a target, usually a metal absorber, or with a crystalline structure. This method of x-ray production is known as bremsstrahlung.
The bremsstrahlung produced is proportional to the square of the energy of the accelerated electrons used to produce it, and is also proportional to the atomic number (Z) of the target (absorber).
Many different types of machines produce x-rays, either intentionally or inadvertently. Some devices that can produce x-rays are x-ray diffractometers, electron microscopes, x-ray photoelectron spectrometers, and Van de Graaf accelerators.
X-rays can also be produced by the attentuation of beta particles emitted from radionuclides.
electron
X-ray

27. Characteristic X-rays
Characteristic x-rays are produced by transitions of orbital electrons from outer to inner shells. Since the electron binding energy for every element is different, the characteristic x-rays produced in the various elements are also different. This type of x-radiation is called characteristic radiation because it is characteristic of the target element. The effective energy characteristic x-rays increases with increasing atomic number of the target element.

29. Bremsstrahlung Radiation
A projectile electron that completely avoids the orbital electrons on passing through an atom of the target may come sufficiently close to the nucleus of the atom to come under its influence.
Since the electron is negatively charged and the nucleus is positively charged, there is an electrostatic force of attraction between them.
As the projectile electron approaches the nucleus, it is influenced by a nuclear force much stronger than the electrostatic attraction.
As it passes by the nucleus, it is slowed down and deviated in its course, leaving with reduced kinetic energy in a different direction.
This loss in kinetic energy reappears as an x-ray photon.

30. Bremsstrahlung RadiationZ2 A
Bremsstrahlung production =

31. Photon Energy and Total Power
As the voltage increases the penetration increases
As the Current increases the dose rate increases
Dose
(Current)
Energy
Voltage
(Penetration)
The total power
W = V x A

32. Photon Energy and Total Power
Characteristic X-ray
Gamma Peak
(Specific Energy)
Dose
Energy

33. Photon Energy and Total Power
Average Energy = 1/3 Maximum Energy
Dose
Energy

34. Photon Energy and Total Power
Adding Filtration
Filtration can shift the average
Energy (voltage) higher
Current
Voltage
(Penetration)

35. Interaction with Matter
When x-rays pass through any material
some will be transmitted
some will be absorbed
some will scatter
The proportions depend on the photon energy and type of material

36. Emission
Radiation Emission

37. Absorption
Absorption

38. Reflection
Reflection

39. Skyshine
Skyshine

40. X-ray Safety for Operators
Decrease dose to the operator
Time
Determines total dose
Voltage
Determines penetration
Current
Determines dose rate

41. Produces damage through ionization and excitation
Ionizing Radiation
Produces damage through ionization and excitation

42. X-ray Safety Filtration removes low-energy
x-rays from the primary beam.
Collimation limits the
beam to a useful area.
Compliance testing
performed periodically.
Registration of sources
with regulatory agency.

43. Medial X-ray Shielding

44. Open Beam XRD
Example of an unenclosed (open) x-ray diffractometer (Geology Department).
The open x-ray beam of such an instrument can be extremely hazardous, and it is far preferable to enclose the entire x-ray apparatus.

45. XRD (tin/polycarbonate enclosure)
Properly enclosed and interlocked x-ray diffractometer. The enclosure is made of tin-impregnated polycarbonate.
Leaded glass enclosures are also used.
If a panel is opened while the XRD is being used, the interlock should either shut off the x-ray or close the shutter, preventing accidental exposure to personnel.

46. Bioeffects

48. At HIGH Doses, We KNOW Radiation Causes Harm
High Dose effects seen in:
Radium dial painters
Early radiologists
Atomic bomb survivors
Populations near Chernobyl
Medical treatments
Criticality Accidents
In addition to radiation sickness, increased cancer rates were also evident from high level exposures.
Narrative
The Picture of woman using fluoroscope. Just off the picture to the right is the business end on an X-ray machine beaming toward her face.
The beam hits the phosphors on the back of the “telescope” and she can she her hand as an X-ray and watch it move…. She also gets a whopping dose to the face!
Throughout this century, people have been exposed to radiation. Some through accident or ignorance; others, like the atomic bomb survivors or medical patients, where exposed intentionally.
Extensive data has been collected on these exposures in an attempt to understand more about it’s effects.
At high doses of radiation, we know there are physical effects such as burns, radiation sickness and even death.
Another observed effect of high doses of radiation is a detectable increase in certain cancer rates. Not a sure thing, but rather a slight increase over the natural incidence of cancer for large exposures.

49. Law of Bergonie and Tribondeau
The more rapidly reproducing cells are more radiosensitive.
The least functionally differentiated cells are more radiosensitive.
1903

50. Dividing Cells are the Most Radiosensitive
Rapidly dividing cells are more susceptible to radiation damage.
Examples of radiosensitive cells are
Blood forming cells
The intestinal lining
Hair follicles
A fetus
Suggested narrative:
When cells are dividing (or undergoing mitosis) they are more susceptible to radiation damage because the cells don’t have their full suite of repair mechanisms. Because of this, cells that are often dividing like
The cells that create our blood or line our intestine, also
Hair follicles, and, of course, fetal cells
are more susceptible to radiation damage.
This is why the fetus has a exposure limit (over gestation period) of 500 mrem (or 1/10th of the annual adult limit)
Specialized or slowly dividing cells, like brain cells are radio-insensitive.
Credit: The vedio (and voiceover) was Excerpted from DOE’s Transportation Emergency Preparedness Program (TEPP)
This is why the fetus has an exposure limit (over gestation period) of 500 mrem (or 1/10th of the annual adult limit)

51. Biological Effects of Radiation
are dependent upon:
Total energy deposited
Distribution of deposited energy
Low dose, low-dose rate radiation exposure. The effects are in great dispute. It is thought that the effects of a protracted dose of radiation are not as great as with an acute dose because of biological repair mechanisms.

52. Relative Radiosensitivity of Mammalian Tissues
Sensitive
Spermatogonia
Lymphocytes Hematopoietic Tissues
Less sensitive
Epithelium
Epidermus
Resistant
Central nervous system
Muscle
Bone

53. Cell Cycle

54. Prompt – effects that appear quickly
Bioeffects
Somatic (body) effects of whole body irradiation can be divided into "prompt" effects and "delayed" effects.
Prompt – effects that appear quickly
Delayed – effects that may take years to appear
Prompt
Diagnostic X-ray
Exposure
Delayed

55. Direct versus Indirect Effects
Damage to DNA through ionization and excitation
Indirect Effects:
Decomposition of water in the cell.
Interaction of directly altered molecules
with other molecules

56. Bioeffects
Three levels of effects that can occur days to weeks after a large, whole body exposure to radiation:
Hematopoietic syndrome (~ rem): effects on blood-forming organs; infection, anemia
Gastrointestinal syndrome (~ rem): destruction of cells lining the intestines; diarrhea, electrolyte imbalance
Central Nervous System syndrome (5000- rem and higher): damage of central nervous system function; muscle coordination loss, seizures, coma
It is important to note that whole body radiation exposures of magnitudes shown above are extremely rare and not associated with x-ray diffraction.

57. Radiation Syndromes Three syndromes from acute doses
Hematopoietic
Blood system
Gastronitestinal
Instestinal tract
Central nervous system
Progression through the syndromes
Prodromal (initial)
First set of symptoms
Latent
Asymptomatic period
Period of illness
Characteristics of prodromal stage reoccur along with additional symptoms
Recovery or death

58. Biological effects depends on whether it is an ACUTE DOSE or a CHRONIC DOSE.

59. Chronic Exposure Dose delivered in small increments over a long time
Effects appear slowly
(many years)
Relatively low incremental
doses required

60. Genetic Effects Somatic Heritable
Damage to genetic material in the cell
May cause cell to become a cancer cell
Probability is very low at occupational doses
Heritable
Passed on to offspring
Observed in some animal studies but not in humans

61. Prenatal Radiation Exposure
Sensitivity of the unborn
Rapidly dividing cells are radiosensitive
Potential effects
Low birth weight - (most common)
Mental retardation
Chance of childhood cancer

62. Measurement of Severity
Prodromal Effects
Time of onset
Degree of symptoms
Duration of symptoms
Hematological Changes
Lymphocyte counts
Physical Dosimetry
Attendant readable

63. Factors that determine biological effect
Dose rate
Total dose received
Energy of the radiation
Area of the body exposed
Individual sensitivity
Cell sensitivity

64. Exposure Effects 1000 rad - second degree burns
2000 rad - intense swelling within a few hours
3000 rad - completely destroys tissue
4000 rad acute whole body exposure is LD 50/30
LD 50/30 - lethal to 50% of population within 30 days if
not treated

65. Skin Effects
Erythema is a reddening of the skin caused by the expansion of small blood vessels in the outer layers of the skin.
Exposure (R)
Time Period
Effects
< 300 R
Somatic effects generally not observed
300 – 800 R
24 – 48 hours
8 – 14 days
1 month
Temporary hair loss
Erythema
Maximum erythema pain
Recurrence of erythema (last 2-3 weeks)
> 1500 R
Long term
Scar tissue, radiation dermatitis

66. Bioeffects- X-rays and Skin
Most radiation overexposures from analytical x-ray equipment are to the extremities.
For x-rays of about 5-30 keV, irradiation of the fingers or hands does not result in significant damage to blood-forming tissue.
At high exposures some general somatic effects to the skin can occur. Very high exposures may necessitate skin grafting or amputation of the affected extremity.
Biological effects can be observed at 10 rem in special blood studies. Typically effects are visually observed at 50 to 100 rem.

67. X-Ray Burns vs. Thermal Burns
Most nerve endings are near the surface of the skin
High energy x-rays penetrate the outer layer of the
skin that contains most of the nerve endings so one does not feel an X-Ray burn until the damage has been done
X-rays penetrate to the deeper, basal skin layer, damaging or killing the rapidly dividing germinal cells, that are destined to replace the outer layers

69. Accident Case Study
Case Study - A radiation accident at an industrial accelerator facility from: Health Physics, Vol. 65, No. 2, August 1992, pp Reproduced by permission.
3MV potential drop accelerator. 40 rad/s inside victim’s shoes, 1300 rad/s to hands.
3 days after exposure
Note erythema and swelling
1 month after
Note blistering and erythema
2 months after

70. As Low As Reasonably Achievable
ALARA
As Low As Reasonably Achievable