M2

most commonly used collimator in nuc med

parallel hole collimator

what ratio hence no magnification or minification

1 to 1 ratio

which collimator does not distort the image

parallel hole collimator

collimators are designed so that septal penetration is kept to what percentage

5% or less

increasing sensitivity usually reduces resolution, how do u fix this?

place detector as close to patient as possible

how do we increase sensitivity of detector?

widening the window (larger holes)

increase in sensitivity causes what?

loss in resolution

GAP is design to make a resonable compromise between?

spatial resolution and sensitivity

high sensitivity is designed with what kind of holes?

shorter and larger diameter holes

low energy collimator used with what kind of energy?

150 keV

medium energy collimator used with what kind of energy?

364 keV (i-131)

four major considerations used in designing scintillation camera collimator?

geometry, desired spatial resolution, geometric efficiency, and energy discrimination.

llinear coefficent equation?

linear coeff (u1)= p (density) x mass atten coeff ( Um)

what does t, d, and l reprsent in a collimator design equation

t=thickness of septa

d=diameter of collimator holes

I= length of the septa

what collimator is best for small organs?

diverging collimator

what does a diverging collimator do to image?

magnify or minify the radionuclide distr.

where is diverging collimator mainly used and why?

SFOV cam, increases the FOV by 1/3

diverging collimator formula?

i/0= f-t / f+b

in a diverging collimator formula, what does f, t, b mean?

f= face to convergeance point

t= collimator thickness

b= collimator to source distance

in diverging collimator, as object-dector distance increase, fhe FOV DOES WHAT?

increases

in converging collimator, image is what as the FOV decreases as the distance to the face of the collimator increases?

increases

converging collimator mag formula?

f+b/ f+t-b

an increase in collimator resolution yields a decrease in ?

collimator counting efficiency

medium energy coll are more or less efficent than leaP/

less efficient than LEAP.

increasing the camera-object distance causes a what in resoultion?

decrease

we can improve resolution by what the diameter of the collimator holes or increase their length

reducing