patient interactions
DESCRIPTION
Patient Interactions. 2010 FINAL. Patient Interactions. ______________ ______________ ______________ ______________ ______________. Interaction in the body begin at the atomic level _______________ _______________ _______________ _______________ _______________. - PowerPoint PPT PresentationTRANSCRIPT
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Patient Interactions
1. ______________
2. ______________
3. ______________
4. ______________
5. ______________
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Interaction in the body begin at the atomic
level
1. _______________
2. _______________
3. _______________
4. _______________
5. _______________
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Some radiations are energetic enough to rearrange atoms in materials through which
they pass, and can therefore he hazardous to living tissue.
1913
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EM Interactions with Matter
General interactions with matter include:1. ______________
– With or without partial absorption
2. ______________ – Full attenuation
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Interactions of X-rays with matter
1. ________________: X-ray passes completely and get to film
2. ________________: no x-rays get to film
3. ________________________________
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Photoelectric effect
1. Low energy (low kVp) x-ray photon ejects inner shell electron (energy absorbed)
2. Leaving an orbital vacancy. As vacancy is filled a photon is produced
3. More likely to occur in absorbers of high atomic number (eg, bone, positive contrast media)
4. Contributes significantly to patient dose,
5. As all the photon energy is absorbed by the patient (and for the latter reason, is responsible for the production of short-scale contrast).
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FIG. 9–3 Photoelectric absorption interaction.
(Modified from Carlton RC, Adler AM: Principles of radiographic imaging, an art and a science, ed 4, Thomson Delmar Learning, 2006, Albany, NY. Reprinted with permission of Delmar Learning, a division of Thomson Learning: http://www.thomsonrights.com.
Fax 800-730-2215.)
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8 p+ + 8e- = neutral atom
1. Incoming photons form tube
2. Pass by the electrons in the patient
3. Do not interact with e–
4. Causes them to vibrate- releasing smnall amounts of heat
CLASSICAL SCATTER IN PATIENT
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Classical (Coherent) ScatteringClassical (Coherent) Scattering
1. Excitation of the total complement of atomic electrons occurs as a result of interaction with the incident photon
2. No ionization takes place
3. Electrons in shells “vibrate”
4. Small heat is released
5. The photon is scattered in different directions
6. Energies below 10K keV
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FIG. 9–2 Classic coherent scatter interaction.
(Modified from Carlton RC, Adler AM: Principles of radiographic imaging, an art and a science, ed 4, Thomson Delmar Learning, 2006, Albany, NY. Reprinted with permission of Delmar Learning, a division of Thomson Learning: http://www.thomsonrights.com.
Fax 800-730-2215.)
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Compton scatter1. High energy (high kVp) x-ray photon ejects an
outer shell electron. 2. Energy is divided between scattered photon
and the compton electron (ejected e-)3. Scattered photon has sufficient energy to exit
body. 4. Since the scattered photon exits the body, it
does not pose a radiation hazard to the patient.
5. Can increase film fog (reduces contrast)6. Radiation hazard to personnel
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FIG. 9–4 Compton scatter interaction.
(Modified from Carlton RC, Adler AM: Principles of radiographic imaging, an art and a science, ed 4, Thomson Delmar Learning, 2006, Albany, NY. Reprinted with permission of Delmar Learning, a division of Thomson Learning: http://www.thomsonrights.com.
Fax 800-730-2215.)
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COMPTON SCATTERING
1. ______ shell electron in body
2. Interacts with x-ray photon from the _________
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Differential Absorbtion
• Results from the differences between xrays being abosorbed and those transmitted to the image receptor
1. ____________________________
2. ____________________________
3. ____________________________
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Compton and Differential Absorbtion
1. Provides ____ useful info to the image
2. Produces image ________• dulling of the image • NOT representing ___________ information
3. At ____________ energies
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Photoelectric and Differential Absorbtion
1. Provides _________________ information
2. X-rays do not reach film because they are __________________
3. ______ energies (more differential absorbtion)
4. Gives us the ______________ on our image
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No interactions with Image Receptor and Differential
Absorbtion
1. No interaction
2. Usually ____________ kVp
3. Goes ______________ body
4. Hits ____________ ________________
5. Usually represents areas of __________• _____atomic numbers
6. Results in __________ areas on the film
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1. The probability of radiation interaction is a function of tissue electron density, tissue thickness, and X-ray energy (kVp).
2. Dense material like bone and contrast dye attenuates more X-rays from the beam than less dense material (muscle, fat, air).
3. The differential rate of attenuation provides the contrast necessary to form an image.
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FIG. 9–5 Pair production interaction.
(Modified from Carlton RC, Adler AM: Principles of radiographic imaging, an art and a science, ed 4, Thomson Delmar Learning, 2006, Albany, NY. Reprinted with permission of Delmar Learning, a division of Thomson Learning: http://www.thomsonrights.com.
Fax 800-730-2215.)
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FIG. 9–6 Photodisintegration interaction.
(Modified from Carlton RC, Adler AM: Principles of radiographic imaging, an art and a science, ed 4, Thomson Delmar Learning, 2006, Albany, NY. Reprinted with permission of Delmar Learning, a division of Thomson Learning: http://www.thomsonrights.com.
Fax 800-730-2215.)