positioning midterm

two main methods for contrast administration (routes)

-gastrointestinal (oral, enteral)

-intravascular (injection, parenteral)

what are two other methods of contrast administration that are less used?

-intraarticular (injection into a joint space)

-intrathecal (injection around spinal cord, for myelography)

this type of contrast adds density, increases attenuation of the beam. examples are barium, iodinated water soluble contrast

positive agents

this type of contrast decreases density. less attenuation of the beam. examples are air, fizzies

negative agent

two types of iodinated contrast used for injection (not the brand names)

-iodinated non-ionic contrast

-iodinated ionic contrast

this type of iodinate contrast dissociates into two ions. benzene ring bond breaks. this was lower cost and used more often in the past. But it had higher chance of reaction due to osmosis, and greater risk of toxicity to cells)

iodinated ionic contrast

atomic number of iodine

53

this iodinated contrast is the one used today. it is hydrophilic (water-soluble) and is easy for IV injection and is safer. caution must still be used though.

iodinated non-ionic contrast

in CT tissues need a difference of about ____ HU to be visibly different

10 HU. (contrast can change it about 40-75)

in CT dose usually about ___, ____, ____ cc depending on machine etc

60,100,150 (not sure what she meant by this but it was in slides)

number of particles in a solution per unit liquid as compared with blood

osmolality

this type of liquid has about the same number of particles in the solution as per unit as blood

Isotonic

this liquid has more particles in the solution per unit than blood

hypertonic/hyperosmolar

contrast can have up to ___ times the number of particles in solution per unit blood

7

these type of agents have about 7 times the number of particles as blood

high osmolality agents

these type of agents have about 2 times as many particles as blood

low osmolality agents

low osmolality agents are used with patients who have _____ impairment.

kidney impairment (high BUN/creatinine) maybe one kidney

this is the thickness or the friction of a substance as it flows.

viscosity

contrast is a ____agent. warming it is very important for IV contrast it makes it easier to push and less likely to cause a complication at injection site.

viscous

atomic number of barium

56

barium made for x-ray and CT is not the same. X-ray barium would cause streaks in CT. CT is about ___-___ % barium. x-ray is about ____-____% x-ray is more dense.

1-3% and 96-98% for x-ray

reasons barium should not be given? (contraindications)

-dont give to r/o appendicitis

-if chance of perforation (recent colonoscopy, bariatric surgery)

-pt has diverticulitis, diverticulosis.

-recent abdominal surgery especially to bowel

this is when barium leaks into the peritoneal cavity it is associated with significant mortality rate

barium peritonitis

barium reactions are unlikely, but it is possible since it contains sulfa. chances are ___-_______ patient more likely to react to additive used for flavor.

1-500,000

iodinated water soluble contrast can be diluted and use orally. but it can stimulate ____ and cause diarrhea and cramping. this also travels faster through GI tract than barium

peristalsis

high and low osmolality contrast are still always _____ compared to the blood

hypertonic

high osmolar agents are _____ meaning they dissociate into two ions.

ionic

what happens when hypertonic solution (high or low contrast) is injected

body strives for homeostasis. water in the tissues moves to the blood vessels via osmosis. this is to create balance. (the shift is what they think causes reactions)

three predisposing factors for contrast reaction (in order of most likely to least)

1 prior reaction to contrast

2 asthma

3 severe allergies to other substances

two categories of contrast reactions

chemotoxic

idiosyncratic

this category of contrast reaction has to do with speed and dose of injection and the chemical makeup of the contrast. hemodynamic injuries, and nephropathy are examples.

chemotoxic

category of contrast reaction. this is unpredictable and is not related to dose. qualified as “allergy” but unlike an allergy antibodies are not released. so it is an allergic like reaction.

idiosyncratic

this is a type of vasogenic shock. due to severe allergic reaction caused by release of histamine in the body in response to foreign substances and a severe drop in blood pressure.

anaphylactic shock

this drug is a bronchodilator. used when patient is SOB, wheezing, have chest tightness, asthma.

Albuterol (pro-air, preventil, ventolin)

this drug is an anticonvulsant given when patient is having seizures.

Diazepam (Valium)

this drug is a vasoconstrictor and can be given when patient has hypotension.

Dopamine

this drug is an antihistamine. it can be given for hives, rash, itching

diphenhydramine (benadryl)

this is a vasoconstrictor. given when pt has bronchospasm, facial edema, severe urticaria, laryngospasm, peripheral vascular collapse.

Epinephrine (epi-pen)

this is a diuretic. given when patient has hypertension emergency, pulmonary edema, heart failure

Lasix (furosemide)

this is a vasodilator. used for hypertension, angina, arterial spasm

nitroglycerin

this is an antiinflammatory. it is preventative used for shock, and anaphylaxis

methylprednisone, solumedrol

some analgesics

morphine, demerol, tylenol

some antianxiety meds

ativan, valium, xanax

some anticoagulants

heparin, coumadin (warfarin)

antihypertensive medication

lopressor

some antiinflammatory medications

motrin, ibuprofen

antiulcer medication

zantac

this can treat cardiac arrhythmias. aids defibrillation

lidocaine (xylocaine)

this is an antiemetic

compazine

this is a laxative

dulcolax

this type of reaction involves limitied urticaria, sneezing, rash, transient nausea and emesis. headache vertigo. minor tachy or bradycardia. if they continue sneezing a lot it may be worse.

mild reaction to contrast

this reaction has tachycardia bradycardia and pt may have a weak pulse that may be rapid. mild hypotension. and wheezing. major cutaneous reaction and hives that do not respond to initial treatment.

moderate reaction to contrast

this reaction may involve convulsions, seizures, profound hypotension or total loss of blood pressure. pulmonary edema, epiglottal edema, cardiopulmonary arrest. pulmonary arrest

severe contrast reaction

when doing a mobile chest x-ray if it comes out looking like this what went wrong

clavicles are above the apices. the patient may have been lordotic or the tube may have been angled more cephalic

when doing a chest x-ray and the patient is kyphotic (c-shaped) what should you not do with your angle?

don’t angle caudally. it will just make the distortion worse.

if you angle caudally too much when doing a portable chest x-ray what might happen?

distortion. clavicles look like handlebars and are farther down.

what causes this artifact

heating blanket. make sure to remove things that can cause artifact in mobile (within reason)

where is mobile radiography commonly performed

neonatal unit, patients room, emergency department, ICU, surgery, recovery rooms.

what is a major technical factor you need to consider with mobile radiography?

your time. Mobile has kVp and mAs settings but mAs automatically sets the mA and time to preset values. So if you use a grid and need more mAs for example you need to think about how time is also going to increase, and this could lead to patient motion.

it depends on the manufacturer but mAs in mobile ranges from ___ to ____

.04 to 320 mAs

depends on manufacturer but kVp in mobile units ranges from ___ to ____

40 to 130 kVp

technical considerations for mobile radiography

grid

anode heel effect

SID

(mAs too)

what are some issues you may run into when using a grid during mobile

for a grid to work it needs to have the central ray centered, it must be level, and it must be at the right focal distance (radius). when placed under a patient on a mattress the grid may be “off level.” also must make sure you are the correct distance.

if the central ray is ___ to ____ inches off the midline of a grid it can cause cutoff

1-1.5 inches

in this grid error the lateral margins of the image have less density.

off focus grid error

grids with _____ grid ratio have a wider focal range, but they also are less efficient at cleaning up scatter

less

what two grid ratios are commonly used in mobile radiography

6:1 and 8:1 (focal range is 36 to 44 inches)

this is software that estimates scatter radiation and provides scatter correction without use of a standard grid.

virtual grid

when is the anode heel effect more noticeable

-short SID

-large field size

-small anode angle

short SID and larger field sizes are common in mobile radiography. try to position tube to take advantage of anode heel.

where should the cathode be in chest x-ray mobile

at the diaphragm

where should cathode be in decubitus chest mobile image

at the downside of the chest

in mobile abdomen where should cathode be

at diaphragm.

in decubitus abdomen mobile imaging where should cathode be

it should be toward downside of abdomen

in mobile pelvis imaging where should cathode be

upper pelvis

where should cathode be for mobile lateral and ap femur

at proximal femur

in mobile lateral c-spine where should cathode be

over the lower vertebrae. (40 in SID only)

in mobile radiography the SID should be ____ inches for most mobile exams. if you use a longer SID requires more mAs which would lead to a longer exposure time.

40 inches.

what are some things that should be available on the mobile radiography unit

calipers, shield, technique chart

covers, tape, sponges, markers, grid

what is the recommended minimal distance for a radiographer in mobile

6 feet and try to stand 90 degrees to the primary beam and object being radiographed

most effective means of protection for radiographer in mobile imaging

distance

safety tips for mobile radiography

shields for radiographer and patient, or those who are nearby and can not leave. distance. inform those around that an exposure is going to be taking place.

SSD can not be less than ____ inches

12 inches

this is isolation used to protect the patient from receiving microorganisms.

reverse isolation

some PPE you may wear in isolation when doing mobile radiography

gloves, mask, eyewear, shoe covers, gown. (strict isolation you need mask, gown, and gloves if patient has drainage)

what type of cover should be on the IR in isolation

a clean impermeable one. pillowcases do not work. they can have the body fluid soak through.

when positioning for mobile radiography (especially when pt is in a traction device etc) what is important? (when it comes to moving etc)

moving the IR and the tube around the part as opposed to moving the patient.

when doing a portable chest what position do you want to have the patient in if possible

as upright as possible. the greatest angle they can tolerate. supine can be done if patient is critically ill or injured

top of IR in mobile chest x-rays should be about ___ inches above the relaxed shoulders

2 inches. (if supine shoulder may be higher)

what can you do with patients arms to prevent scapulae in lung field for mobile chest

internally rotate their arms

central ray for mobile chest

enters 3 inches below the jugular notch. (t7)

for an ap chest x-ray with patient in lateral decubitus they should be elevated ___ to __ inches via a fim support

2-3 inches

how long should patient be in decubitus position to asses for fluid or air

five minutes (for chest you want to see affected side upper lung for air and lower for fluid)

centering for ap decubitus abdomen (according to book)

book says 2 inches above crest and that pubic symphysis and bladder do not need to be seen since this is for air fluid levels

for ap abdomen projection in lateral decubitus what side do you want the patient on

left side. so as not to confuse gastric bubble as free air

which is preferred for mobile femur projection lateromedial or mediolateral

mediolateral since more of the proximal femur is visualized.

for lateral c-spine x table mobile top of IR should be ___ in above EAM. so you are centered to ____

1 inch. so you are at C4

steps to the speak up initiative (surgical avoiding wrong site, wrong patient)

-pre procedure verification

-surgical site marking

-time out right before starting procedure

this takes place in the operating room right before the procedure. include document review like looking at medical records or notes, diagnostic images, need for antibiotics, and other essential med needs and allergies

all activities stop anyone who believes there is wrong info must speak up.

time out

who calls time out usually

circulating nurse

20-30 percent of this occurs from errors occurring even before patient is admitted. can be from inaccurate chart notes, mislabeled x-ray image, mix up of patients with similar names. etc

wrong site, wrong patient procedure