Radiation/Imaging Flashcards by Linsay AugustinCRNA

Conduction

• Direct transfer of energy through physical contact

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Convection

• Indirect transfer of energy through a medium (ex. Heated air)

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– Radiation

• Transfer/Emission of energy as electromagnetic waves or moving subatomic particles, especially high-energy particles that cause ionization.

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Energy can be transferred from one object to

another in three ways

Conduction
Convection
Radiation

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&Electromagnetic (EM) - photons

– Gamma rays
– X-rays
– UV

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Particulate

– Alpha (He2+ nucleus)

– Beta (electron or positron)

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Electromagnetic Radiation (EM)
• Composed of________
• Varying amounts of energy depending on_________

photons

wavelength (λ) & frequency (ƒ)

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Isotopes –

two or more forms of the same element with an equal numbers of protons but different numbers of neutrons in their nuclei

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differ in relative____________but not in ________

atomic mass but not in chemical

properties

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________emit subatomic particles to decay down

to a stable state

• Unstable,

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AS it loses protons, becomes less stable

also lose neutrons

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Ex. of alpha decay – atom of Uranium 238

–

Emits an alpha particle (Helium nucleus)

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β− decay (electron emission) –

n → p + e- + oῡe

neutron is converted into a proton, an electron, and an

antineutrino

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Formula for B- decay

n → p + e- + oῡe

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β+ decay (positron emission) –

proton is converted into a neutron, a positron, and a

neutrino

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Formula for B+ decay

p → n + e+ + υe

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Electron Capture Decay (“K-capture”)
Define
The neutrino is \_\_\_\_\_\_\_\_From the 
If the new nucleus is left in an excited state, \_\_\_\_\_\_\_\_will also be emitted
formula?

• When an inner shell e- is drawn into the nucleus
and combines with a proton, forming a neutron and
a neutrino.
The neutrino is ejected from the atom’s nucleus.
• If the new nucleus is left in an excited state, gamma
rays (γ) will also be emitted.

p+ + e- → n + υe + γ

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Half-Life (t1/2)

• The time it takes for the radioactivity of a specified

isotope to decay to half its original value.

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• Example of Half life

• If we start with N0 atoms, after one half-life ½N0
remain.
• After two half-lives, ¼ N0 are left.
• After three half-lives 1/8 N0 are left and so forth.
• After seven half-lives, only (1/2)7 N0 remain.

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Scatter Radiation

Occurs as a result of attenuation of the incident

beam to the patient’s body.

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Three types of scatter radiation are

Coherent, Compton, Photoelectric

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***Coherent scatter

• a.k.a.

“Thompson scatter”
– Occurs when an incident photon collides with an atom.
– The atom momentarily absorbs the energy and moves
into an excited states.
– The atom then releases the same energy as another
photon traveling in a different direction as scatter rad.

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***Compton Scatter

Occurs when incident photon collides with outer
orbital e-. The e- is ejected from its orbit. The
photon is deflected from its original path and
continues with decreased energy in a new direction
as a scatter radiation.

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*****Photoelectric scatter

• Occurs when an incident photon collides with an
inner shell orbital e-. The e- is ejected. When an
outer orbital e- moves to the inner orbit to fill the
vacated space, the difference in binding energy
between the 2 electron shells is emitted in the form of a new scatter photon.

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Ionizing vs. Non-ionizing

• Ionizing radiation carries enough energy to free electrons from atoms or molecules, thereby ionizing them. • Ionization of cell structures, organelles and DNA cause severe cellular damage.

Penetrating energies are measured in electron volts | eV

- a unit of energy ~ equal to 1.6×10^-19 joules

Alpha particles can be stop by

paper or skin

Beta particles can be pass ______And stop by _____

Human tissue: thin aluminum

Gamma rays particles and xray

thick sheet of iron and lead can stop it

Neutrons

thick wall containing hydrogen can stop

Boundary of ionizing photon energy is

between 10eV and 33 eV in the UV range.

Non ionizing

Radio Microwave Infrared Visible

Ionizing

mid ultraviolet Xray Gamma

2 types of cell interactions from ionizing radiation:

– Direct hit | – Indirect hit

• Direct hit:

breakage of a DNA molecule as a result of | being struck directly by EM or Particulate radiation.

• Indirect hit:

H2O breakage into H+ + OH- free radicals, which then chemically damage DNA. Cells may mutate and die

Somatic effects

– Short-term | – Long-term (“latent”)

Short term effects Heme GI CNS

Further categorized according to body system affected: – Hematologic (dysplastic anemia) – GI (“radiation sickness” damaged mucosal lining w/ infx) – CNS (seizures, coma, death)

Short term effects occurs

3 months after exposure | Involve very high doses (

Long-term Effects | • Observed at_______Avg________

5 – 30 years, avg. at 10 – 15 years

• Latent effects of long term low dose ionizing radiation | –

Cataracts (with extensive fluoroscopy) – Cancer (skin, thyroid, breast & leukemia) – Shortened Life span

Genetic effects

• Occurs with radiation exposure to reproductive organs (testes & ovaries) • Involve mutations to the genes of the reproductive cells • Mutations carried over to progeny

Two systems used to measure radiation dose:

conventional and SI units

Conventional units

Roentgen Rad Rem

Roentgen (R) is a

unit of Exposure

1 R =

2.58 x 10^-4 C/kg

Rad (rad) is a unit of • Absorbed Dose = • Rad stands for “

Absorbed Dose (D) the amt. of energy per unit mass absorbed by tissue. Radiation absorbed dose”

1 roentgen ~ 1Rad • Corresponding SI unit is the • 1 Gy = rad • 1 rad =

of absorbed dose in muscle tissue Gray (Gy) 100 0.01 Gy

Rem (rem) is a unit of • Biologic effects of radiation vary according to the_________ • Rem stands for_________ • Corresponding SI unit is the Corresponding SI unit is the

``` Equivalent Dose (EqD) type of radiation involved. “radiation equivalent man” Sievert Sievert (Sv) ```

* To calc. occupational dose, a radiation_____________ | * WR values are based on

``` weighting factor (WR) is assigned to each type of radiation. variation of biologic damaged produced by each type of radiation. ```

``` Equivalent dose (EqD) is calculated by multiplying absorbed dose by ```

D x W(r)R = EqD

• Ex. Worker receives 10rads alpha particles and | 5rads x-rays. EqD =

• (10rads x 20 = 200) + (5rads x 1 = 5)

1 Sv = _____rem | • 1 rem = ______Sv

100 | 0.01

Doses are__________ in occupational exposure, devices (dosimeters) are worn to

cumulative | monitor doses received.

______of the common units are typically used

1/1000

Dosimeter “film badges”

- Common types include thermoluminescent-type (TLD) - optically stimulated luminescence-type (OSL)

ALARA -acronym:

As Low As Reasonably Achievable

3 Factors of ALARA: –TDS

Time – Distance – Shielding

Shielding Equipment:

* Lead aprons * Thyroid shields Pb gloves Leaded glasses

Ionizing Tests: examples

x-rays, CT, nuclear scans

Non-ionizing Tests:

US, MRI

______most common ordered imaging study (second | to________

CXR | dental films

PET – Positron Emission Tomography

``` • Pt. injected with beta emitter • FDG (fluorodeoxyglucose) • Fluorine -18 tagged to glucose • Sensors detect emissions from pt. ```

PET/CT

• Combines both tests in one machine, provides highly detail information of anatomy and cell physiology in one test.

SPECT scan

• Single-photon emission computed tomography • Unlike PET/CT, Spect uses gamma emitting radioisotope (ex. Galium111) • 3D images for neurologic and cardiac studies

MRI

• Non-ionizing. Magnetic field aligns H2O molecules • RF disturbs H2O, molecules reorient, sensors record as image

ECHO 2 types

TEE vs. TTE

TEE Advantages: –

``` Heart rests on esophagus, only a few mm of tissue vs. chest wall (skin, fat, muscle, bone, lung tissues) – Better visualization of structures ```

TEE Disadvantages: –

Pt. must be NPO – Takes longer than TTE – Requires sedation or Gen. anesthesia

``` Ultrasound: Ionizing/nonionizing Transducer contain what? waves reflect? Receiver senses Used in _________ • For optimal visualization of structures, transducer must be ```

• Non-ionizing. Uses sound waves to image. • Transducer contains piezoelectric crystal that vibrates to generate high freq. sound waves. • Waves reflect off internal structures. Receiver senses reflected signal echo. •Used in regional anesthesia. manipulated.

Echogenic needles

Common needles used for regional blocks • Smooth needles (A.) reflect sound energy away from transducer.

Radiation/Imaging Flashcards

(71 cards)