CH 10 Emission Spectrum 💛

Properties/ Characteristics

Describes attributes/ traits of a substance Unique properties that represents that substance; makes it distinctive, distinguishing, individual

8. Cause fluorescence of certain elements

Fluorescence= the emission of light

Interactions

Deals with transfer of energy between atoms that may cause a reciprocal action or effect, e.g. ionization

Electromagnetic Spectrum

Entire range of electromagnetic radiation A continuum of electromagnetic energy which contains a wide range of radiation energies Describes any phenomenon that can be measured in an orderly continuous progression of values: - from very short wavelenths and very long wavelengths, - from very low frequencies to incredibly high frequencies

7. Cannot be optically focused by a lens

Focused= condensed, concentrated, converged Light can be focused, X-rays CANNOT

Secondary Radiation

Generally lower in energy Does not bring any good= can cause harm to patient / personnel Can have detrimental effects to image quality Comes in form of: leakage radiation from the tube, and scattered radiation from the body/ anatomy

6. Travel at the speed of light in a vacuum

Speed of light= 3 x 10^8 meters per second (m/s) or 186,000 miles per second

What is the X-ray emission spectrum?

the graph of energies within a diagnostic x-ray beam x-axis: represents kV energies y-axis: represents # of x-ray photons

what are the three types of generators?

(1)single phase, full wave rectified unit (2) 3-phase, 12-pulse generator (3) high-frequency generator

12 properties/ characteristics of X-rays

1. Highly penetrating, invisible rays 2. Electrically neutral and have no mass 3. Polyenergetic, Heterogeneous 4. Releases small amounts of heat upon passing through matter 5. Travel in straight lines 6. Travel at the speed of light in a vacuum 7. Cannot be optically focused by a lens 8. Cause fluorescence of certain elements 9. Can cause chemical changes to occur in radiographic imaging plates 10. Can penetrate the human body and ionize matter 11. Produce chemical and biological changes in matter through ionization and excitation 12. Produces secondary and scatter radiation

Truths about EM Spectrum

All radiations travel at the speed of light All are bundles of energy with varying electric and magnetic fields All particles of radiation have photons (quanta) A photon (quantum) has both wave and particle properties because it interacts with matter by transferring an amount of energy (All differ in wavelength and frequency) Examples of EM radiation: heat, radiowaves, microwaves, Infrared, white(visible) light, ultraviolet, X-rays, gamma radiation

when quantity increases...

Amplitude increases (more x-rays are produced)

11. Produce chemical and biological changes in matter through ionization and excitation

Biological changes: can be useful in treatment of cancer or... harmful in causing cancer Chemical changes: have power to affect and change certain chemicals/ phosphors... can cause chemical changes in human cells

Wavelength

Distance between wave crests An inverse relationship!! Amount of energy in wave increase as wavelength gets smaller and tighter Shorter wavelength = more energy Longer wavelength = less energy

Leakage Radiation

From the X-ray tube that does not exit through the collimator opening: penetrates through tube-housing and/or through the sides of the collimator (Acceptable level of leakage radiation: 100 mR per hour, measured at a distance of 1 meter)

3. Polyenergetic, Heterogeneous

Having wide range (span) of energies and wavelengths Polyenergetic = many different energy strengths Heterogeneous = many mixed frequencies/wavelengths

9. Can cause chemical changes to occur in radiographic imaging plates

IP has an active phosphor layer= BaFBr-Eu (barium fluorobromide doped with europium) (Barium fluorohalide doped with europium= mix of halides not just bromide)

10. Can penetrate the human body and ionize matter

Ionizing radiations are so high in energy that when they interact with materials, they can remove electrons from the atoms in the material. This effect is the reason why ionizing radiation is hazardous to health and provides the means by which radiation can be detected

Ionizing electromagnetic waves

Must have short wavelengths (gamma rays, X-rays, and the upper ultraviolet part of light)

Non ionizing radiations

Not energetic enough to ionize atoms but interact with materials in ways that create different hazards than ionizing radiation Examples: microwaves, visible light, radiowaves, tv waves, ultraviolet light

Frequency

Number of cycles (waves) passing a point per second Higher frequencies have shorter wavelengths Lower frequencies have longer wavelengths

Amplitude

One half crest to valley

Electromagnetic radiation

Radiant energy resulting from electric and magnetic fields/ forces in space A combination of oscillating electric and magnetic fields that travel in a vacuum at the velocity of light ALL EM radiation involves emission of both particles and energy Waves can be described by their wavelengths, amplitude, energy, and frequency

Primary Radiation

Radiation emitted directly from the X-ray tube Not yet reached patient Doesn't carry any useful information yet (must penetrate something)

Remnant/ Exit/ Image Formation Radiation

Radiation that comes out from the body part after passing through it Produces radiographic image Influenced by the absorption characteristics of the tissue examined

Scatter Radiation

Radiation which has changed in direction from the primary beam Travels in random directions (isotropic) Carries no useful signal or subject contrast Obscures image with useless noise (fog)

12. Produce secondary and scatter radiation

Secondary radiation: consists of leakage and scatter radiation Scatter radiation: interaction of X-ray photons and matter that causes a change in direction of the photons... a form of secondary radiation

2. Electrically neutral and have no mass

X-radiation cannot be deflected or affected by electric or magnetic fields ( mass is not weight!! Mass = quantity of matter)

What is an X-ray photon?

X-radiation particles are called photons or quanta Photons (plural)= quanta Photon (singular)= quantum X-rays are forms of electromagnetic ionizing radiation X-rays are electromagnetic waves X-rays have very short wavelengths Short wavelengths allow X-rays to easily penetrate low density material (flesh), but are absorbed by high density material (bone)

How does added filtration affect the emission spectrum?

absorbs low energy x-rays, increases overall average energy, decreases quantity of photons, reduced bremstrahhlung emission more on left than on right. (amplitude decreases, curve shift occurs more on the left than on the right.)

when quality increases...

amplitude and position shift to the right (better quality/ more penetrative rays)

How does mA, mAs effect the emission spectrum

directly proportional to quantity (increase mA, mAs = increase amplitude)

How does kVp effect the emission spectrum

effects both quantity and quality directly (increase kVp= increase amplitude and shift to right) increase in kVp means more electrons have more energy to produce x-rays. Higher kVp= more and higher quality x-rays

effect of target material on emission spectrum

effects both quantity and quality. increase atomic number= increase production efficiency of brems. radiation, increase # of high energy x-rays vs. low energy x-rays, increase energy of characteristic radiation

how does generator type effect emission spectrum?

effects both quantity and quality. brems curve move to the right and amplitude increases. characteristic also increases in quantity.

factors that affect the emission spectrum

kVp Generator Output mA, mAs (tube current) Time Filtration (changing any of these will result in a change of quality or quantity of the x-ray beam)

Quantity

number, amount, intensity of x-ray photons in the beam

Quality

the penetrative power of the primary beam