Exam 1: Radiology/ Laser Safety Flashcards
(76 cards)
1
Q
Who/when discovered X-ray therapy and how?
A
- Wilhelm Roentgen (1895)
- While experimenting with currents in a glass tube noticed that a fluorescent screen in the lab began to glow.
- Placed objects between the screen and the tube –> called “x” ray = something unknown
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Q
What are the four types of radiation?
A
- Electromagnetic = from motion of atoms (combined with electricity and magnetism)
- Mechanical = travel through substances (not much travel through air)
- Nuclear (neutron) = unstable atom nuclei
- Cosmic (beta) = electrons only; travels at almost speed of light (ex: sunlight)
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3
Q
What is non-ionizing radiation?
A
- Radiation that cannot knock electrons off atoms and doesn’t break molecular bonds
- Only harmful from heat energy (ex: radiowaves or microwaves)
This is the stable form of radiation because it doens’t kick off electrons
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Q
What is ionizing radiation?
A
- These types of radiation knock off electrons which create ions
- Ion electrical charge causes intracellular chemical changes
- Risk can be additive (can add up)
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5
Q
What are the negative effects of ionizing radiation?
A
- Break DNA chains = cell apoptosis
- Mutate DNA chain = cancer
- Mutated sperm or egg cell = birth defects
Berry Pops Miniature Candy Each Day
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6
Q
What are the similarities of x-rays to visible light rays?
What is the difference?
A
Similar:
- Both are electromagnetic energy
- Carried by particles called photons
Difference in energy levels (wavelengths): higher energy = higher frequency
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Q
X-rays have _______ wavelengths and _________ energy.
Radio waves have _______ wavelengths and ________ energy.
A
- X-rays have shorter wavelengths and higher energy (high frequency).
- Radio waves have longer wavelengths and lower energy (low frequency).
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Q
How is light emitted?
A
- Caused by the movement of electrons in an atom
1. Moving particles excite atoms (when heated)
2. Electron “jumps” to a higher energy level (orbit)
3. To fall back to the original orbit, it must release energy (photon or light)
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9
Q
How do smaller atoms affect the amount of photons released?
A
- Electron orbitals are seperated by low jumps in energy
- Less likely to absorb X-ray photons
- This will show up as a greyish color on the X-ray image
Ex: soft tissue
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Q
How do larger atoms affect the amount of photons released?
A
- Greater energy difference between orbitals d/t orbits being further apart
- More likely to absorb photons
- This will show up as a whiter or brighter color on the X-ray image
ex: bones
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11
Q
What makes up an electrode pair of an X-ray machine?
A
- Cathode
- Anode
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12
Q
What is a cathode?
A
- A filament (in the center) shape that is heated up as machine charges.
- The heat filament current causes electrons to fly off of filament
- Negative charged side of the x-ray tube
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13
Q
What is an anode?
A
- A positively charged metal disc of tungsten that will attract electrons across the tube from the cathode
- This absorbes the photos to caputre the xray
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14
Q
Components of the x-ray machine (3)
A
- Thick shield surrounds the entire machine
- The window in the shield allows a narrow beam of photons to escape
- A camera is on the opposite side of the tube that records the patterns of the X-ray photons
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Q
What does the camera of the x-ray machine do?
A
- Produces a chemical reaction on the film
- Ambient light can darken or lighten - so take the picture in a dark room
- Intensity changes to photon beam (over/under exposure) alter appearance
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16
Q
What do we use medical x-rays for?
A
Diagnostics
Radiography
- bone fractures, tube placement, foreign objects
Mammography
Computed Tomography (CT)
- 3D image generated when x-ray combines with computer processing
Fluoroscopy
- real-time image (with/without contrast)
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17
Q
Can x-rays be used theraputically?
A
- YES, as radiation therapy
- At higher doses, radiation can damage the cancer cell’s DNA
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18
Q
What is the most common side effect of radiation therapy?
A
Fatigue
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19
Q
How is radiation measured?
A
- REM = radiation dose x weighting factor
- nearly equilivalent to a Rad
- measured as milirem (mrem) or 1/1000 of a Rem
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20
Q
Annual allowable radiation dose:
- Whole body in 1 year
- Extremities
- Eye lens
- Pregnancy
A
Whole body in 1 year = 5,000 mrem
Extremities = 50,000 mrem
Eye lens = 15,000 mrem
Pregnancy (after 2nd/3rd) Trimester = 500 mrem
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21
Q
What is known as the direct sources of radiation?
A
- Primary X-ray beam
- Leaking from other sites within the equipment
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22
Q
How much Rem exposure comes from the following sources:
CXR
Coronary angiogram
CT
Angioplasty
A
- CXR: 5-10 mrem
- Coronary angiogram: 1,500 mrem (b/c it uses fluro)
- CT: 5,000 mrem
- Angioplasty: 5,700 mrem
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Q
How do we minimize direct radiation?
A
- stay 6 feet away to minimize scatter
- use lead or protective equipment
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Q
What are indirect sources of radiation?
A
- Scattered radiation: This is radiation that reflect off tables, patients, and other surfaces
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What are three factors that affect scatter radiation?
* Collimation (width of the beam; wider collimation has more radiation scatter)
* Object thickness (thicker patients - obese - will result in **more** radiation scatter)
* Air Gap (distance between patient and cassette; the greater the distance, the more radiation scatter)
COG
| S17
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How much rem will cause transient erythema?
* 200,000 mrem
*studies looked as pts with high amounts of radiation from hospital settings and they only saw transient erythema with high doses - so minimal symptomes with xrays*
* Fetal doses <10,000 mrem after 20 weeks are unlikely to have effects
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What is ALARA?
- As Low As Reasonably Achievable
- Radiation protection
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What are the 3 things to reduce radiation?
1. Limit time spent near beam entry
2. Distance
- direct source: **double distance from beam = 1/4 the exposure rate**
- indirect source: scatter = > 6 ft from patient
3 . Shielding
- lead aprons, portable shields, thyroid, lead glasses
DTS: Down To....Shit?? haha
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What is a dosimeter?
A badge that measures the cumulative radiation over time (usually per year)
| Lecture and slide 20
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How do you wear the dosimeters?
Two badges:
1. Outside the apron on the collar
2. Inside the apron on the waist
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What are the 3 "Don'ts" to dosimeters?
1. Don't mix up (outside or inside badge)
2. Don't share dosimeter with others
3. Don't leave in the car on the dashboard/seat
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41 residents were involved in a monitoring project for 3 months with occupational radiation exposure
* 82% had "high" or "very high" exposure = concerning
* <10% had recommended whole body exposure exceeding
* <4% had recommended eye exposure exceeding
| lecture and S21
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The principles of MRI are based on interactions between what two things?
* Based on the interaction between the static magnetic field and individual atom nuclei.
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The magnetic field of the MRI is used to orient the nuclei of ____ molecules to north-south poles.
* Hydrogen
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How does the MRI create an image?
* Radio wave pulses change the orientation of specific atoms, which radiates energy to create an image.
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How is contrast between tissues generated?
* Contrast is generated by time til tissue relaxation when the radio frequency is turned off.
* When the radio frequency is turned off, protons realign with the magnetic field releasing electromagnetic energy.
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What factors affect the tissue contrast generated?
* Various densities of hydrogen nuclei in tissues
* Different chemical and physical properties of the tissues
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What are the two contrast images for MRI?
* T1 contrast/ view
* T2 contrast/ view
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Describe a T1 contrast/view.
* Relaxation of the **magnetic vector**
* Radio frequency is off and not trying to move the orientation of the atom
* Provides a good grey-white matter contrast
* **Good for viewing anatomy**
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How do fat and water appear on a T1 weighted image?
Fat appears bright
Water appears dark
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Describe a T2 contrast/view.
* **Axial spin** relaxes
* Radio frequency turned on
* Great for identifying tissue edema
* Good for viewing pathology
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How do fat and water appear on a T2 weighted image?
Fat is darker
Water is lighter
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What is the most common contrast material used for MRI?
* Gadolinium
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How does Gadolinium enhance the equality of MRI images?
* Gadolinium dye alters the magnetic properties of nearby water molecules, enhancing the quality of MR images.
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What are the side effects of Gadolinium?
How is it cleared from the body and how quickly?
* Mild side effects: itching, rash, abnormal skin sensation
* Cleared with normal GFR in 24 hours. (Kidney clearance)
| S26
## Footnote
25mg benadryl should take care of itching
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In the MRI room, what do ferro magnetic objects experience?
* Attractive force - they are pulled toward the center of the magnet
* Torque - an attempt to line up with the magnetic field
| S27
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Is the magnetic field always on?
YES
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Examples of ferro magnetic objects
* O2/Nitrous tanks
* Anesthesia machine
* Monitors
* Infusion pumps
* Stretchers
* Crash carts
| S27
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Risks in MRI?
* Projectile risk
* Radiofrequency energy causes tissue/device heating (not that common though)
* Electromagnetic interference causes artifacts such as the **interpretation of ECG artifact**
* Acoustic noise up to 125 dB == wear hearing protectors (CRNA and patient) - this dB level is a loud as a chainsaw
REAP the risks of MRI
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Anesthesia plan for MRI
* We are usually called to MRI for claustrophobia (they usually just need sedation) - they must hold still for each imaging sequence *up to 10 min each sequence*
* Sedation or GETA: PO or TIVA, **sevo** is the MRI-safe vaporizer
| S29
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What are the AANA Standards of Care for MRI?
* EKG, pulse ox, BP, capnography q 15 minutes when providing anesthetics
* Airway (cannula, mask, ETT vs. LMA)
* Suction
* Spontaneous ventilation vs. ventilator
* Minimize movement (versed comes in handy)
* Complications (ex. airway access)
* MRI-compatible infusion pumps…. vs long, long, IV tubing
* Laryngoscope handles, blades…induction may occur in a separate room
| S30
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Things to know about patient positioning for MRI?
* Head and neck scans will result in an inaccessible airway.
* Abdominal scans will have the patient's arms over their head. This can lead to brachial plexus injuries.
*As always, minimize extreme positions*
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What objects could be in the patient that can be effected or affect the MRI scan?
* Pacemakers
* AICDs
* Implanted insulin pumps
* New generations of these devices are MRI-compatible
| S32
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When the provider does this, it can cause dizziness, HA, light flashes and nausea
rapid movement towards the magnetic field (>1m/sec)
| S32
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What objects are considered MRI-compatible?
* Heart valves are safe
* Endovascular and biliary stents are usually embedded after eight weeks
* Coronary stents OK immediately
* Vascular ports and IVC filters are safe
* Any Orthopedic implants...titanium, safe; screws are made of lead and securely in bone.
| S32
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What does L.A.S.E.R. stand for?
* Light Amplification by Stimulated Emission of Radiation
| S35
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What is ordinary light vs laser light?
* Ordinary light contains many wavelengths that spread out in many directs
* Laser has a specific wavelength with a focused narrow beam and high intensity
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The unexcited state electrons orbit the nucleus at the ____ energy.
* lowest
| S37
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In the unexcited state, electrons occupy orbits ____ to the nucleus.
* closest
| S37
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How is radiation produced?
* As the electrons absorb energy from a source, they become excited and move to a higher orbit
* Upon return from an excited state to ground state, they spontaneously emit photons of energy (electromagnetic radiation)
| S37
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Properties of Laser Radiation?
* **Monochromatic:** All photons in the laser beam are the same wavelength
* **Coherence:** Travel of photons is synchronized in time and space (not random movement)
* **Collimation:** Laser beam photons are parallel (allow the beam to focus on a small area)
| S38
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Advantages of LASERs
* Precision
* Good hemostasis (bovi a vessel and colguate)
* Rapid healing
* Less Scar formation
* Less postop edema and pain
* Lower infection rates
| S39
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What gives a type of laser its name?
* The Lasing Medium
| S40
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What are the 3 lasing mediums?
* Argon
* Carbon dioxide
* Nd:YAG
| S40
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What should be known about Argon lasers?
* Used in dermatology
* Modest tissue penetration (0.05-2 mm)
| S40
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What should be known about CO₂ lasers?
* Used in vocal cords, oropharynx
* Scatter is minimal
* Surrounding tissue damage is negligible and absorbed by water/disperse little heat
| S40
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What should be known about Nd:YAG lasers?
* Most powerful laser
* Used for tumor debulking (prostate, bladder tumors)
* Deeper tissue penetration (2-6 mm)
| S40
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What are the 5 hazards of laser?
What are the two hazards CRNAs are most concerned with for lasers?
* **Atmospheric contamination** (most concern) - particulate masks
* **Airway fire** (most concern)
* Perforation of a vessel or structure
* Embolism
* Inappropriate energy transfer
| S41
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# Atmospheric Contamination
What is a Laser Plume?
* Fine particulates produced d/t vaporization of tissue
* Laser Plume can result in HA, nausea after inhalation
* Laser Plumes could cause interstitial pneumonia, bronchiolitis, emphysema
* Laser Plumes could be carcinogenic
*Definitely use a particulate mask*
| S42
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LASER safety
* laser glasses for provider
* laser glasses with gauze tape for pt
* windows covered
* laser plume masks for vaporized viruses
* appropriate suction
* water/saline irrigation on the back table (to put out a fire if there is one)
* dont tent drapes/have pockets of oxygen (this decreases fire ignitors)
| S43
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What makes up the fire triad?
* Ignition source (aka Laser)
* Fuel (drapes, ET Tube, nasal cannula)
* Oxidizer (oxygen)
| S44
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What are the two major sources for OR fires?
* ESU (Electrosurgical units aka "Bovie")
* Laser
| S44
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What are some scenarios for endotracheal fire discussed in the lecture?
* Surgeon is lasering airway through the ETT and burns through PVC tube…
* Surgeon is completing tonsillectomy in a pediatric patient with an uncuffed tube…
* Surgeon uses bovie to “cut” through trachea for a tracheotomy…
*For all of these scenerios, decrease the O2 concentration to 21% if the pt can tolerate it to decrease the oxidizer close to the ignitor*
| S45
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How to prevent Airway fire?
* Laser-resistant ETTs
* Low-inspired (21% if possible) O2
* Wet pledgets around the ETT (tape strings to face to prevent loss)
* Methylene blue in the ETT cuff (visual)
* Use scissors to cut into trachea instead of bouvie (for emergent airway or planned trachostomy)
* Remove ETT during laser procedure and reinsert ETT prn sats
| S46
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Anesthesia Plan for the patient undergoing Laser therapy.
* Preoperative evaluation of airway (stridor, flow volume loops, CT, fiberoptic eval)
* Mutual planning with surgeon) **Intermittent apneic oxygenation**, jet ventilation)
* Total IV anesthesia (Propofol, remifentanil, Xylocaine spray) - TIVA because apnic ventilation will affect your gas - duh
| S47
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Anesthesia plan to prevent airway fire:
* Methylene blue in cuff
* Saline gauze protection of airway/face
* Short, repeated pulses of laser instead of long continuous mode
* Keep O2 < 30%, avoid nitrous
* Communicate and monitor video camera for signs of airway fire
| S48
