BUN

 normally 5 to 25 mg/dl

Creatinine

 normally 0.6 to 1.7 mg/dl

PT

normally 10 to 14 seconds

PTT

normally 20 to 40 seconds

Platelet count

normally 150,000/mm^3 to 400,000/mm^3

Two ways radiation can cause damage:

- direct interaction with DNA bonds

- indirect effect caused by ionization of chemicals in the body

Typical skin radiation dose for CT head

1 to 5 rads

Typical skin radiation dose for CT body scan

 2 to 6 rads

Typical skin radiation dose for localizer scan

0.05 to 0.1 rads

(3) hardware factors affecting dose

- x-ray tube to pt distance

- filtration

-pre-patient collimation

Increasing the pitch results in a __________ MSAD

decreased

Normal values for adult blood pressure

Systolic 110 - 140 mm

Diastolic 60 - 80 mm

Normal values for adult respiration

10 -20 breaths per minute

Normal Values for adult pulse

 50 to 100 beats/min

The slip ring transfers:

- electrical power

-scanning instructions

-detected signals

x plane

left to right

y plane

anterior to post

z plane

 head to feet

transverse/axial plane is perpendicular to the direction of the z-axis

electrons bear a _________

electrical charge

negative

loss of energy is converted into

xray photons 

 bremsstrahlung radiation

xray photons generated by either:

-the electron directly colliding with the nucleus

-the electron entering the vicinity of the nucleus w/out colliding with any particle of the atom

(also called braking radiation)

characteristic radiation

fast moving electron collides with electron in the inner shell ejecting it, outer shell electron moves in releasing excess energy which is emitted as xray photons

target material made of :

tungsten atoms

10 to 12% of radiation is from

characteristic radiation

tube voltage

kV

tube current

mA

What determines the number of x-ray photons produced?

mA

tungsten target material is where?

anode

3rd generation scanners vantage point

 xray tube

4th generation scanner vantage point

detector

CT number

value of each ray

 Requirements of the scanner

for helical scanning (2)

-continuous rotation slip ring

- high heat capacity x-ray tube

w/ rapid cooling capabilitie

Mathematical Interpolation

process of taking helical scanning and makeing slices out of it

slice thickness (helical scanning)=

table increment (in mm per 360 degree ratation) divided by pitch

Pitch

term that describes the extension of a helix

 Pitch (of a helical scan) =

the table increment (in mm per 360 degree rotation) divided by slice thinkness (in mm)

 Kernal=

filter

convolution

process of apply filtration to data

primary responsibility of a filter

ensure anatomy is presented

accurately in the final image

film is

single emulsion

Pitch of less than 1 indicates

overlapping of anatomy

3D surface rendering is

performed on ________ data

image

intensity of the laser beam in a laser image is directly proportional to

the intensity of each pixel printed