Chapter 3 Flashcards
Diagnostic Imaging and Techniques
A voxel is described as:
(a) A two dimensional image produced by a cone beam scan
(b) A digital x-ray image that is typically 512x512 pixels
(c) A digital image element that has height, width and depth
(d) A volume element that is always 4096 values
C…..A digital image element that has height, width and depth.
A digital three-dimensional image is described by an image matrix that has individual image/picture elements called voxels. A digital three-dimensional image is described not only by its width and height and pixels (i.e., 512 × 512) but also by its depth/thickness.
Regarding implant site evaluation, The American Academy of Oral and Maxillofacial Radiology guidelines state:
(a) that a panoramic xray is adequate and is all that is necessary
(b) that it should be evaluated with a three-dimensional imaging technique such as computerized tomography
(c) that the imaging modality that requires lowest xray dose must always be used
(d) all of the above
B…..that it should be evaluated with a three-dimensional imaging technique such as computerized tomography.
The American Academy of Oral and Maxillofacial Radiology guidelines state that all implant site evaluations should be evaluated with a three-dimensional imaging technique such as conventional or computerized tomography.
What area of the mouth is subject to the least magnification on a panoramic radiograph?
(a) anterior maxilla
(b) anterior mandible
(c) posterior maxilla
(d) posterior mandible
C…..posterior maxilla
The density of D2 bone on a CT scan is expressed in Hounsfield unit and is:
(a) 850-1250
(b) 0.25-1.0
(c) 1750-2500
(d) 25000-30000
A…..850-1250
The use of MRI is indicated:
(a) as a routine baseline for treatment planning of implant surgeries
(b) to determine bone density
(c) to locate the thickest areas of cortical bone
(d) for evaluation of infection, inferior alveolar canal and the maxillary sinus.
D…..for evaluation of infection, inferior alveolar canal and the maxillary sinus.
MRI would be a viable alternative as the trabecular bone is easily differentiated with the inferior alveolar canal. In cases of nerve impairment or infection (osteomyelitis), MRI may be used because of added advantages including differentiation of soft tissue with respect to CT
What percentage of the time is the mental foramen absent on a panoramic radiograph?
(a) 50%
(b) 38%
(c) 12%
(d) pretty much 100% of the time
C…..12%
When evaluating the mental foramen on periapical radiographs, studies have shown that on 50% of periapical radiographs, the mental foramen is not visible.96 Many studies including dry skull evaluations conclude that the mental foramen is absent in approximately 12% of panoramic radiographs.
What is the modality of choice for long term post prosthetic evaluation of crestal bone?
(a) Occlusal x-ray
(b) Panoramic x-ray
(c) Periapical or Bitewing x-ray
(d) MRI
C…..Periapical or Bitewing x-ray
When is CT imaging recommended for presurgical planning?
(a) For every patient requiring implant placement
(b) Division A bone
(c) All bone divisions including Division A when vital structures are approximate
(d) Only for division C and D bone
C…..All bone divisions including Division A when vital structures are approximate (Misch 3rd Ed. Pg 58)
When post surgical sinus complications arise, the recommended choice of imaging would be?
(a) CT scan
(b) PA x-ray
(c) MRI
(d) Panoramic x-ray
A…..CT scan
Today, no radiographic modality gives more information of the paranasal sinuses than CT, which is the gold standard for viewing the osseous structures and evaluating pathology in the sinuses.
When fabricating diagnostic templates, what amount of barium sulphate should be added to cold-cure acrylic to best indicated tooth position on an CT image?
(a) 2%
(b) 10%
(c) 50%
(d) 90%
B…..10%
What is the (ALARA) principal
A) Always Leave Apical Radiolucencies Alone
B) Always Learn A Reasonable Amount
C) As Low As Reasonably Achievable
D) Apply Large Area Restorations Anteriorly.
C) As Low As Reasonably Achievable
In dental and medical radiology, a recommended principle when selecting the appropriate radiographic modality is based on radiation dosage. The “as low as reasonably achievable” (ALARA) principle should always be adhered to that states that the diagnostic imaging technique selected should include the lowest possible radiation dose to the patient.
Which of the following is an Objective of Preprosthetic Imaging:
A) Identify disease B) Determine bone quality C) Determine bone quantity D) Determine implant position E) Determine implant orientation D) All of the above
D) All of the above
The average absorbed radiation dose from a CBVT scanner (NewTom 3G) is approximately 12.0 mSv (micro sieverts). This dose is equivalent to:
A) Twelve D- Speed dental x-rays or 90% of the radiation from a typical panoramic radiograph
B) A full Mouth Series using D-Speed dental x-rays
C) Five D-speed dental x-rays or 25% of the radiation from a typical panoramic radiograph
D) the 6 hours you spend texting on your cell phone during a Maxicourse lecture
C) Five D-speed dental x-rays or 25% of the radiation from a typical panoramic radiograph
What is a Hounsfield unit?
A) 12.0 mSv
B) A unit of measure for quantifying golden retrievers while field hunting wild game
C) 12 bits
D) the value of a voxel (said three times fast)
D) the value of a voxel
The individual element of the CT image is called a voxel, which has a value, referred to in Hounsfield units, that describes the density of the CT image at that point.
Which brings up… Whats a Voxel?
A) 0 Hounsfield units
B) The individual element of a CT image
C) a 12.0 mSv measurement
D) A make of car that proceeded Voxelwagon
B) The individual element of a CT image
CT images are inherently three-dimensional digital images, typically 512 × 512 pixels with a thickness described by the slice spacing of the imaging technique. The individual element of the CT image is called a voxel, which has a value, referred to in Hounsfield units, that describes the density of the CT image at that point.
