rad 165 final Questions and Correct Answers

1




rad 165 final Questions and Correct
Answers

Question: another term for unsharpness
Answer: blur


Question: a perfect MTF for an imaging system
Answer: 1


Question: which of the following represents the formula for calculating
geometric unsharpness
Answer: focal spot size x OID/ SOD


Question: which of the following shapes would exhibit the least
structural shape unsharpness if each was radiographed after being
accurately aligned to the x-ray beam
Answer: trapezoid


Question: if you change source to image distance in order to increase
detail, which formula must be considered if equal density is to be
maintained?
Answer: new mAs


Question: the effect on sharpness of recorded detail: increase SID from
40-48 inches
Answer: +


Question: the effect on sharpness of recorded detail: decrease OID from
10 to 3
Answer: +




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Question: the effect on sharpness of recorded detail: use CR imaging
plate known to have dust particles on plate
Answer: -


Question: the effect on sharpness of recorded detail: use 200mA
instead of 100mA
Answer: 0


Question: the effect on sharpness of recorded detail: increase the
filtration from 2mm to 3mm Al
Answer: 0


Question: the effect on sharpness of recorded detail: change the focal
spot size from large to small
Answer: +


Question: the effect on sharpness of recorded detail: a 280lb patient
abdomen compared to a 115lb pt abdomen
Answer: -


Question: in digital systems spatial resolution frequency signal must be
samples twice from each cycle. This is known as
Answer: Nyquist criterion


Question: quantum mottle is "grainy" unwanted noise with a
degradation of image detail. What is the best way to combat or avoid
quantum mottle?
Answer: increase exposure quantity


Question: which of the following does not cause poor contact in an IR?
Answer: increased room temp


Question: sharpness of detail is ______________ property
Answer: geometric

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Question: the smaller the focal spot the ________ the detail
Answer: better


Question: the longer the OID the ___________ the detail
Answer: worse


Question: the longer the SID the ___________ the detail
Answer: better


Question: what is the term used to describe the unsharpness at the
edges of curved objects (like our bones or vessels)
Answer: edge gradient


Question: according to your text, normal human visual acuity is limited
to the ability to distinguish ____line pairs/mm
Answer: 5


Question: aliased images that occur during low frequency wrapped over
high frequency imaging resulting in 2 slightly out of alignment images are
said to have this type of appearance/pattern
Answer: moire


Question: focal spots are not capable of imaging structures smaller than
themselves (T/F)
Answer: true


Question: which of the following uses the divergence of the beam to an
advantage for less distortion
Answer: PA lumbar spine


Question: proper explanation of the procedure and the use of
immobilization is most helpful in the control of


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Answer: voluntary motion


Question: short exposure times are more helpful in controlling
Answer: involuntary motion


Question: another term for magnification is
Answer: size distortion


Question: magnification is influenced by the geometric factors of
Answer: OFD or OID and TFD or SID


Question: the width of penumbra (unsharpness) can be mathematically
calculated using which of the following formulas
Answer: FSS x OID/SOD


Question: which of the terms means to disperse equally in all directions
Answer: isotropic


Question: true distortion may involve which of the following
Answer: shape


Question: when the central ray part IR relationship is aligned so the
beam is centered to the IR and area of interest, the _______ amount of
shape distortion occurs
Answer: least


Question: The part, or area of interest, is usually recorded with minimal
distortion if it is placed:
Answer: parallel with the IR


Question: magnification is ________ related to sharpness of detail
Answer: Inversely



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