CT Patient Care / CT Radiation Safety

2 types of Contrast Used

Water Soluble Iodine

Barium Sulfate

Water-Soluble Iodine

chemically bound to benzene rings to mak eit biologically COMPATIBLE TO THE BODY

ONLY CONTRAST acceptabel for IV

Is Ionic, Non-ionic, High and Low Osmolar

Ionicity

whether an iodinated contrast medium dissociates into charged particles (ions) when dissolved in the bloodstream

Ionic: dissociate into charged particles in the presence of water and blood

Is known to be more toxic to pateints, becasue of its high Osmolarity

Non-Ionic

common used for pateints, do not form charged particles in the blood(safest)

Osmolarity (thickness)

measure of osmotic pressure of a solution about the number of particles per volume of a solution.

Highest : Ionic, Metrizoate(Isopagque 370) that is 2100

Lowest : Non-ionic, Iodixanol(Visipaque 320) that is 290 (blood accpets this easiest)

Ideal Water Soluble Contrast Agent is…

both non-ionic and low-osmolar

Barium Sulfate

for Gi tract/Rectal

High atomic number(z=56)

is suspended in water, not dissolved

only orally and rectally

is NOT THE SAME AS REG. X-RAY, goes through patients quickly instead

Dietary Restrictions

Pre Hydration(helps burden to the kidneys)

NPO for 1 hour ( helps with nausea/vomitting)

Post-hydration (helps burden to the kidneys)

Renal function Evaluation

Blood Urea Nitrogen “BUN”: normal rage is 7-21mg/dl, above 50 may indicate renal failure

Glomerular Filtration Rate “GFR”: normal range is 90-120 ml/min, below 30 indicates renal failure

Creatinine: normal range is 0.7-1.5 mg/dl , above 2.0 indicates renal failure

Pre-Medication

for a know iodine allery, this is Corticosteroid(prednisone), Anti-histamine: diphenhydramine(Benadryl)

Cannulation

for Venipuncture

Process of placing a peripgeral IV

Perferred Sites in Ct for Venipuncture/Cannulation

Cephalic Vein(elbow), Basilic Vein(elbow), Median Cubital Vein(elbow),

If veins fail start from down to upward, Never start going down.

Documentation

Date, Site, Gauge(18-22), Number of Attempt

Gauges: 18(shortest/thickest) 22(skinner/thinner)

Contrast label, Contrast Concentration, Volume, Injection Rate

Peripheral IV

uses of catheter of 20 Gauge or higher in the antecubital or forearm is PERFERRED for Adults (makes the flow faster)

PICC line (peripherally inserted central catheter)

thin, flexible tube inserted into a vein in the upper arm and threaded through larger blood vessels until the tip rests in a large central vein near the heart called the superior vena cava

must be labeled for pressure injection, maximum injection rate is provided

Dialysis Catheters and Jugular lines

NOT ACCEPTABLE for pressure injection

Standard dialysis catheters and temporary central venous catheters cannot withstand the high flow rates and pressures generated by CT power injectors, which risks catheter rupture, extravasation, or air embolism.

Treatment for Air Emblosim

administration of 100% oxygen, placing patient in left lateral decubitus

Mild Contarst Reactions

Urticaria(hives)

Pruritus(itching)

Rhinorrhea(runny nose)

Nasuea/Vomiting

Coughing Dizziness

Moderate Contrast Reactions

Persistent Vomit

Urticaraia(hives)

Headache

Facial Edema(swelling)

Laryngeal edema(throat swelling)

moderate bronchospasm of dyspnea( shortness of breath)

Hypertension(blood pushes on artery walls)

Abdominal Cramps

Treatment of Adverse Contrast Reaction

Oxygen by mask

Bendyral/Antihistamine

Albuteral for bronchospam (inhallar)

Epinephrine(pen) for hypotension and larythgeal edema

Lasix for plmonary edema

Mothers that are nursing/lactaation

instructed to pump and dump for 24 hours of breast milk

CTDI (computed tomography dose index)

index of patient dose(not a true measurement)

its a estimate

average does to any area of the patient in the scan field

normal phantoms of CTDI : 16cm-32cm

CTDI calculated in milligray(mGy): meausred of absorbed dose to patient

DLP(dose-length product)

CTDI x scan length

the product of the dose multiplied by the scan length

DLP: mgy-cm, represents both dose to tissues and total volume of tisssues exposed

milligray(mGy)

measured of absorbed dose to patient

multiply this with scna length to DLP

Dose Documentation

CTDI and DLP MUST be recorded for every CT procedure

recorded in PACS with the image data

Biological Risks

Deterministic Effects: hair loss, skin burns(erythema): would be due to tech’s error

Stochastic(random) Effects: radiation induced cancer, from the build up of years of radiation

Tube Current (mA)

controls number of photons exiting the x-ray tube

increase of mA=increase of patient dose

directly porportional

Tube Potential (kVp)

controls energy and penetration of the x-ray beam

also affects total number of photons from the beam

Higher pitch over 1

gaps in anatomy

faster scan

decrease patient dose

inversely proportional relationship

Beam Width (collimation)

detector width x total number of active detector rows

as beam width increase=patient dose decreases

Automatic Dose Modulation

ability of the CT scanner to change the mA DURING the scan based on the DENSITY of the TISSUES being imaged

Dose Notification / Dose Alert

Notification: displayed on the control panel when the CTDI for the scan will exceed will exceed the predetermined dose notification values “pre”

Dose Alert: warning displayed on the control panel when cumulative CTDI for a series of scans WILL EXCEED 1,000 mGY (1) “alert of pre”

Lead Shieling

CANT ever be placed in the scan field due to it causing an unacceptable level of beam hardening “streaking artifact”

can cause increase of patient dose and increase of tube output

if even used: Bismuth Shield attenuates only low-energy photons and reduce the entrance dose while maintaining image quality

PICC Line’s, Central Line’s Contradiction

MUST be labeled for power injection.

The flow rate for it is descripted/provided on the line itself.

Jugular and Dialysis Lines

NOT SAFE for IV power injections.

Contrast Documentation includes

Contrast Label

Contrast Concentration

Volume

Injection Rate

General Documentation includes

Date of Insertion

Site

Gauge

Number of attempts of Venipuncture/Cannulation

Air Embolism in LLD position

helps prevent the air bubble from traveling to the cerebral circulation or becoming trapped in the right ventricular outflow tract.