2. Radiology Chapter’s 2, 3. & 4

3. Electromagnetic spectrum Unique abilities Some rays visible some are not Penetrates matter Produces latent image Produces fluorescence Light bulb Produces ionization of matter Change matter

4. Matter Anything that occupies space and has mass Matter can be altered by energy Fundamental unit of matter is the Atom Desk Chair Computer Tissue Muscle Teeth Bone Your Patient

5. Atom An atom is the smallest unit of an element, it consist of a positively charged protons found in the nucleus. Negatively charge electrons that orbit around the nucleus. Neutron Proton Electron Electrons

6. Nucleus (Dense core that occupies very little space) Protons Subatomic particles and positively charged Neutrons Subatomic particles and has no charge

7. Nuclear Composition Equal number of protons and electrons form a stable atom. The number of protons and neutrons equals the atomic weight. Force will knock an electron out of their orbit. X-radiation Electromagnetic energy Is this Atom stable or unstable?

8. Ionization ( production of ions) Converting atoms into ions. To produce ions a force or a collision such as x-radiation or electromagnetic energy must eject an electron out from its orbit. Thus making the atom unstable. Spontaneous release excess energy in the form of wave or particles. ION

9. Electrostatic Force Binding energy holds electrons in their orbits (Example: sun and the planets) There are seven shells an atom can have they are k, l, m, n, o, p, and q. K-shell has the highest energy and the strongest binding energy Nucleus q p o n m l k

10. Atoms into ions Positive ions are ionized atoms. An ionized atom has been interrupted by some force: X-radiation Electromagnetic energy Negative ions are electrons out of orbit or unstable structures. This ejected ion will speed off to interact with other atoms. When they interact or collide it sets off a chain reaction and in turn will eject other electrons until the energy dissipates.

11. Elements Substances made up of only one type of Atom

12. Molecule Two or more Atoms make up a molecule Two Hydrogen and one Oxygen = Water Bonded together by electrons on the outer most shells

13. Ionizing Radiation (all radiation cause biological changes) Particulate Responsible for radioactivity Radioactivity is when atoms spontaneously disintegrate or decay. Power plant Atomic bomb Electromagnetic Series of wave like energies with no mass some high energy some low energy Visible and invisible Man made or natural occurring

14. Electromagnetic Energy Made up of both wave and particle that travel in a straight line X-ray = bundle of energy, is termed, x-ray photon which has no mass no charge and travels at the speed of light (186,000 MPS) X-ray photon is what interacts with matter (your patient)

15. Examples of electromagnetic radiation and there wave like patterns Less energy More energy

16. Electromagnetic Energy Wavelength Distance between the crest of the wave to the next wave Frequency Refers to the number of wavelength that pass a given point in a certain amount of time. We can adjust the frequency by kilovoltage

17. Voltage Measurement of electrical force that cause electrons to move from a negative pole to a positive one (Strength) Dental x-ray units require a high level of electrical potential

18. Kilo-Voltage Peak (KVp) Kilovoltage controls the level of penetration Shorter wavelength = more penetrating High frequency = more penetrating Longer wavelength = less penetrating Low frequency the = penetrating Kilovoltage Kilo = 1000 Volatage = volts 110 or 220 Higher voltage means greater energies Dental radiographs require 65 to 100 kilovolts Higher KVp should be used when area is dense or thick Adjust KVp on individual diagnostic needs Overall QUALITY of primary beam

19. Amperage Measurement of electrons moving through a conductor Current is measured in amperes

20. Milliamperes (mA) Milliampere Milli = 1/1000 Ampere = Electrical current NOT voltage mA settings 7, 10, and 15 Thermionic emissions Higher the setting increases temperature resulting in some electrons being ejected out of their orbit. Ampere allows electrical current to flow thru a filament which results in a cloud of electrons Depending on mA setting will depend on the QUANTITY of x-rays produced

21. Milliamperes-Seconds Exposure time Interval of time in which photons are being produced (.117 secs) Longer time = more photons High mA = more photons Both mA and exposure time both have a direct influence on the number of electrons produced If we produce to many photons our dental film will be dark or black

22. Radiographic Density (Degree of darkness or blackness of an x-ray.) Density Amount of radiation reaching the film KV or mA Distance from the x-ray tube to the patient Patient thickness (Density) Developing conditions The more photons that strike the film the more dense (black) the radiograph will appear

23. Tubehead Cathode Negative electrode consist of tungsten filament held in a cup shaped holder made of molybdenum Negative = electrons, therefore electrons are created to produce photons * Electrons held in place

24. Tubehead Anode Positive electrode consist of a wafer thin tungsten plate embedded in a solid copper rod Positive = collision = photons * Collision produced photons (indicated in red)

25. Transformers Three types are used in production of x-rays Step down decreases the voltage from the incoming 110 or 220 to three to five volts required Step up Increases the voltage to 65,000 to 100,000 volts required Autotransformer Compensator

26. Inside the Tubehead

27. This is What Happens Electricity excites the filament at 3-5 volts, creating thermionic emissions, a release of electrons from the tungsten filament when heated, this cloud of electrons stay in place until the exposure button is pushed. The high voltage circuit is activated. The electrons produce are accelerated across the x-ray tube to the anode. The molybdenum cup helps to direct the electrons to the tungsten target. When the electrons strike the tungsten target their energy of motion or kinetic energy is converted to x-ray energy and heat. More heat is created that x-rays and is dissipated through the copper stem and absorbed by the insulating oil. X-rays are produce in all direction only a few will escape through the unleaded portion of the tube. Those x-rays will be directed to the aluminum filter, which will remove the long waves. The collimator will focus the remaining short waves and travel down the lead lined PID and exit the tubehead

28. Production of radiation (not all produce the same in the tube head) General radiation AKA braking radiation An electron passes near the nucleus and is deflected by the positively charge nucleus Once deflected this kinetic energy is converted into photons Bremsstrahlung German (braking radiation)

29. Production of radiation (not all produce the same in the tube head) Characteristic radiation Electron that has been deflected continues to travel ejecting other electrons out of orbit until they loose their kinetic energy Energy in motion

30. Important Terms kVp = Kilovoltage peak=quality of beam kVp = density = low contrast = lots of shades of gray Low kVp = low density = high contrast = lighter film = black & white film Contrast – varying shades of gray Density – overall blackness or darkness of film

31. Important Terms mA=Milliamperage=quantity of x-rays produced=density To many mA’s=darker film=higher density To little mA’s=light film=lower density # of electrons from cathode to anode # of x-ray photons in beam mA regulates temperature of cathode

32. Important Terms Exposure time – refers to interval of time x-rays are produced-measured in impulses Longer time=longer time x-rays emitted=darker film=greater film density Less time=less time x-rays emitted=lighter films= less film density Subject Thickness effects quality and quantity of penetrating power

33. Important Terms Kilovoltage peak rule – RHS – when kVp is increased by 15 – exposure time should be decreased by ½ When kVp is decreased by 15 – exposure time should be doubled Milliampere-seconds (mAs) = combination of milliamperes and exposure time Milliampers X exposure time (seconds) = milliampere-seconds (increase mAs-decrease time)

34. Important Terms Attenuation aka Dose When matter absorbs radiation (only during secondary) Primary Radiation aka Primary Beam Penetrating beam – Roentgen Units = R Secondary Radiation Created when Primary beam hits matter (soft tissues, head, skull, teeth) less penetrating power Radiation pt receives – RAD = radiation absorbed

35. Important Terms Scatter Radiation A type of secondary radiation Has been deflected off of path Travels to all parts of the body & operatory REM = Roentgen equivalent to man MPD = maximum permissible dose Dental radiographer = 5.0 REM per year Non health care worker =.1 REM per year.08 RAD’s in FMX

36. Radiation Biology Radiation Biology-the study of effects of ionizing radiation on living tissue Absorption Ionization page 39 – all x-rays harmful to living tissue When x-rays strike patient tissues ionization results Free Radical Formation-causes cell damage

37. Sequence of Radiation Injury page 41 Latent Period=the time that elapses between exposure to ionizing radiation and the appearance of visible clinical signs. Example: Sitting in the sun – hours later skin redness appears

38. Sequence of Radiation Injury Period of injury After the latent period Cell injury can result as: cell death changes in cell function – ex: endometriosis breaking or clumping of Chromosomes – ex: (cell) reproduction problems many more cell specific Cell injury is the desired result in cancer tx

39. Sequence of Radiation Injury Recovery period Not all cell radiation damage is permanent Damage caused by low-level radiation is repaired within cells of body. Ex: skin was burned – it has repaired itself

40. Sequence of Radiation Injury Cumulative effects – overtime Radiation damage accumulates in tissue of entire body Can lead to: Poor health Cancer – Thyroid/Skin Cataract formation Birth defects Dental x-rays do not cause cancer – falls under MPD

41. Sequence of Radiation injury cont. Recovery period=Not all cellular radiation injuries are permanent. With each radiation exposure, cellular damage is followed by repair. Cumulative effects=The effects of radiation exposure are additive, and unrepaired damage accumulates in the tissues, cumulative effects of repeated radiation exposure can lead to health problems.

42. Determining Factors for Radiation Injury Total dose – RAD – measurement of attentuation – absorbable dose Dose rate – rate @ which exposure to radiation occurs & absorption takes place Cells need time to recover Amount of tissue irradiated – area exposed Cell sensitivity Age

43. Short-Term and Long-Term Effects Short-term page 42 Short-term effects are associated with large mounts of radiation absorbed in a short time. Includes nausea, vomiting, diarrhea, hair loss and hemorrhage. Long-term page 42 Effects that appear after years, decades or generations. Long-term effects are associated with small amounts of radiation absorbed repeatedly over a long period.

44. Somatic and Genetic Effects Somatic effects Somatic cells are all the cells except reproductive cells. Major somatic effects of radiation exposure include the induction of cancer, leukemia and cataracts. These are not transmitted to future generations. Genetic effects Genetic effects are not seen in the person irradiated but are passed on to future generations. The radiation-induced mutations affect the health of the off-spring. Genetic damage cannot be repaired.

45. Radiation Measurements MPD, Maximum Permissible dose The dental radiographer must know radiation measurements to discuss exposure and dose concepts with the dental patient. Traditional or standard system R-roentgen=measurement of radiation REM (Me)=5.0 year or.01 weekly Pregnant operator=0.1 per year RAD (pt.)=0.1 per year

46. Risk Estimates Radiosensitive parts Lymphoid tissue Blood forming tissues Reproductive cells Formative cells Embryo cells Radioresistant parts Salivary glands Kidney Liver Cells of mature bones Muscle Nerves

47. Critical Organs Thyroid Gland Use Thyroid collar Bone Marrow Skin Very sensitive to radiation Eyes Cataract

48. Patient Exposure and Dose pg. 46 Film- Using F-speed film instead of D reduces absorbed dose by 60%. Using F-speed instead of E reduces absorbed dose by an additional 20% Collimation-Radiation exposure can be limited by using rectangular collimation, reduces absorbed dose by 60%-70% rather the round collimation (PID).

49. Patient Exposure and Dose Technique-Radiation exposure can be limited by using a longer source-to-film distance. XCP for example Exposure factors-Radiation exposure can be limited by using a higher Kilovoltage peak, the use of higher kilovoltage peak reduces skin dose. Surface exposure-intensity of radiation @ pt skin surface

50. REDUCING EXPOSURE RISKS Dental radiation risks – estimated 3 to1,000,000 30 PA’s to equal one chest x-ray’s worth of radiation Film speed Collimation – PID use of Rectangular best – most common is round – pointed not used Technique – use film holding devices Exposure – higher kVp less time

51. Risk versus Benefit X-radiation is harmful to living tissues Benefit of disease detection outweighs risk of biological exposure Properly prescribed & exposed – only when needed ALARA Principle – as low as reasonably achievable – minimize risk to pt and operator FMX – full mouth survey – taken no more than once every 3-5 yrs – 14 PA’s & 4 BW’s