Oral Radiology quiz 2

What size film should you use for occlusal radiographs on adults? On children?

4 for adults 2 for children

Select all of the ways to minimize image shape distortion: a. Position film/sensor parallel to long axis of object b. Orient central ray perpendicular to object & film/sensor c. Increasing the object to film/sensor distance

A and B

Which are the high signals for T1-weighted images? a. Fat b. Water c. Bone marrow d. CSF e. Cortical bone

A and C

Select all of the the ways to minimize image size distortion: a. Increasing the focal spot to film/sensor distance b. Decreasing the focal spot to film/sensor distance c. Increasing the object to film/sensor distance d. Decreasing the object to film/sensor distance

A and D

Which of the following is a disadvantage of panoramic imaging (select all that apply). a. Lower resolution images that do not provide the fine details provided by intraoral radiographs b. Magnification across image is unequal, making linear measurements unreliable c. Image is superimposition of real, double, and ghost images and requires careful visualization to decipher anatomic and pathologic details d. Requires accurate patient positioning to avoid positioning errors and artifacts e. Difficult to image both jaws when patient has severe maxillomandibular discrepancy

All all disadvantages

What is an indication of panoramic imaging? (SELECT ALL THAT APPLY) A. Overall evaluation of dentition B. Examine intraosseous pathology C. Gross evaluation of TMJs D. Evaluation of eruption permanent dentition and impacted teeth E. Dentomaxillofacial trauma (trismus) F. Developmental disturbances of maxillofacial skeleton

All of these are indications!

Using ultrasonography, tissues not producing signals, such as fluid-filled cysts, are said to be ___ and appear black. a. Anechoic b. Hypoechoic c. Hyperechoic

Anechoic

Which 3 orthogonal views are used for reconstruction?

Axial, coronal, sagittal

Which are the high signals for T2-weighted images? a. Fat b. Water c. Bone marrow d. CSF e. Cortical bone

B and D

Objects that lie posterior to the center of rotation and that are intercepted twice by the x-ray beam form a ... A. Real image B. Double image C. Ghost image

B. Double image

Image receptor is in front of the patient and perpendicular to the midsagittal plane and parallel to the coronal plane. The canthomeatal line forms a 10 degree angle with the horizontal plane. The Frankfurt plane is perpendicular to the image receptor. A. Lateral cephalometric projection B. Posteroanterior cephalometric projection C. Submentovertex projection D. Water's projection E. Reverse towne projection

B. Posteroanterior cephalometric projection

Panoramic radiographs are taken with a slight negative angulation (angled slightly upward) to allow the x-ray beam to pass inferior to the base of the skull. The correct angle is between -20 to -30 degrees A. Both statements are true B. Statement 1 is true, statement 2 is false C. Both statements are false D. Statement 1 is false, statement 2 is true

B. Statement 1 is true, statement 2 is false The correct angle is about -4 to -7 degrees

The objects in the panoramic radiograph appear bigger and wider because... A. The object is centered in the focal trough B. The object is behind the focal trough C. The object is in front of the focal trough

B. The object is behind the focal trough

What radiographs are utilized in caries detection?

Bitewing and periapical

What radiographs are utilized in periodontal disease detection?

Bitewing and periapical

When using the tube shifting technique to localize a foreign body, the object moved in the opposite direction of the xray source. Is the foreign body on the buccal or the lingual?

Buccal

Which is a low signal for T1- and T2-weighted images (select all that apply)? a. Fat b. Water c. Air d. Fibrocartilage e. Bone marrow f. Liagment g. CSF e. Cortical bone

C, D, F, and E

What step of the CBCT is this step describing? Source detector assembly makes a rotation across the center of rotation. The internal structures of the body attenuate X-rays proportionally to their coefficient of attenuation. The intensity captured by detectors depends on the attenuation of the body tissues. A. Reconstruction B. Visualization C. Acquisition

C. Acquisition

Which of the following is NOT true of panoramic radiographs? A. It is a technique used to produce a single image of the facial structures B. Based on the principle of tomography C. Circular or rectangular beam is used D. The x-ray tube rotates around the patient's head in one direction while the receptor rotates in the opposite direction E. The beam of radiation rotates in a horizontal plane around an invisible rotational axis that is positioned intraorally

C. Circular or rectangular beam is used NARROW vertical beam is used!

Objects are located between the x-ray source and the center of rotation. This type of image appears on the opposite side, superior, blurred, and magnified A. Real image B. Double image C. Ghost image

C. Ghost image

Image receptor is placed parallel to the patient's transverse plane and perpendicular to the midsagittal and coronal planes. The central beam is perpendicular to the receptor. The patient's neck is extended as far back as possible with the canthomeatal line parallel to the receptor A. Lateral cephalometric projection B. Posteroanterior cephalometric projection C. Submentovertex projection D. Water's projection E. Reverse towne projection

C. Submentovertex projection

The objects in the panoramic radiograph appear smaller and narrower because.... A. The object is centered in the focal trough B. The object is behind the focal trough C. The object is in front of the focal trough

C. The object is in front of the focal trough

Selectively images a specific body layer blurring the images on other planes A. Focal trough B. Attenuation C. Tomography D. Collimetry

C. Tomography

Which of the following is false of CBCT imaging? A. CBCT uses pulsed, cone shaped, X-ray beam and produce 150-600 basis images B. Filtered back projection algorithm is used to generate 3D volumetric data set C. Voxels created on CBCT are hypertropic D. CBCT has superior dimensional accuracy in the construction process of raw data because of uniform voxels E. Imaging can be reformatted and viewed in axial, sagittal, and coronal, as well as cross sectional planes

C. Voxels created on CBCT are hypertropic ISOtropic

Posteroanterior skull projections is used to evaluate: A. Facial asymmetries B. Assess orthognathic surgery outcomes C. Assess the midline or maxillary-mandibular relationship D. All of the above

D. All of the above

Which of the following is true about the canthomeatal line? A. Central point of the external auditory canal to the outer canthus of the eye B. Main anatomic landmark used in patient positioning C. Forms a 10 degree angle with the Frankfurt plane D. All of the above are true

D. All of the above are true

Fan beam CT typically has lower resolution but decreased radiation exposure, while CBCT typically has higher resolution and increased radiation exposure A. Statement one is true, statement two is false B. Statement one is false, statement two is true C. Both statements are true D. Both statements are false

D. Both statements are false Other way around!

Which of the following is NOT a disadvantage of panoramic radiographs? A. Magnification across the image is unequal, so linear measurements are not reliable B. Requires accurate patient positioning C. Difficult to image both jaws when the patient has a sever maxillomandibular discrepancy D. Higher resolution images that provide fine details E. Frequent image superimpositions of real, double and ghost images

D. Higher resolution images that provide fine details Pans have a LOWER resolution than intraoral radiographs and cannot provide fine details

Image receptor is placed in front of the patient and perpendicular to the midsagittal plane. The X-ray beam is perpendicular to the image receptor. The patient's head is tilted upward so that the canthomeatal line forms a 37 degree angle with the receptor. A. Lateral cephalometric projection B. Posteroanterior cephalometric projection C. Submentovertex projection D. Water's projection E. Reverse towne projection

D. Water's projection

Which of the following is NOT true about the lateral cephalometric projection technique? A. Patient is placed with left side towards the receptor B. Receptor is parallel to the mid sagittal plane C. X-ray beam is perpendicular to the midsagittal plane D. Wedge filter is placed on posterior of beam for visualization of hard tissues

D. Wedge filter is placed on posterior of beam for visualization of hard tissues Wedge filter is placed on ANTERIOR of beam for visualization of SOFT tissues

What are the 3 main steps of CBCT imaging? A. Acquisition, Recognition, Visualization B. Acquisition, Reconstruction, Diagnosis C. Conversion, Reconstruction, Visualization D. Conversion, Recognition, Diagnosis E. Acquisition, Reconstruction, Visualization

E. Acquisition, Reconstruction, Visualization

Which of the following is true of lateral cephalograms? A. Monitor the progress of treatment and treatment outcomes B. Generates measurements to classify craniofacial morphology C. Cephalostat helps maintain the constant relationship between the skull, receptor, and beam D. Evaluates the relationship between the maxilla, mandible, and cranial base E. All of the above

E. All of the above

Which of the following is NOT a limitation to CBCT imaging? A. Size and cost B. Image noise C. Poor soft tissue contrast D. Amount of radiation exposure to the patient E. Both A and D

E. Both A and D

Image receptor is placed in front of the patient, perpendicular to the midsagittal plane and parallel to the coronal plane. The patient's head is tilted downward so that the canthomeatal line forms a 30 degree angle with the receptor. The patient's mouth should be open so that the visualization of the condylar heads is enhanced. A. Lateral cephalometric projection B. Posteroanterior cephalometric projection C. Submentovertex projection D. Water's projection E. Reverse towne projection

E. Reverse towne projection

Which of the following is a strength of CBCT imaging? A. Size and cost B. Fast acquisition C. Submillimeter resolution D. Relatively low patient dose E. Interactive analysis F. All of the above

F. All of the above

Which of the following is an advantage of panoramic radiographs? A. Broad coverage of facial bones and teeth B. Low radiation dose C. Ease of technique (quick and convenient) D. Can be used in patients with trismus or those who cannot tolerate intraoral radiography E. Useful visual aid in patient education and case presentation F. All of the above

F. All of the above

True or false: Soft tissues are better visualized on a CBCT compared to a fan beam CT

FALSE CBCTs cannot be used to evaluate soft tissue!

True or false: Collimation allows the X-ray beam of a CBCT to expose radiation beyond the region of interest (ROI)

FALSE Collimation LIMITS the X-ray beam exposure to the ROI

True or false: Pterygomaxillary and zygomatic implants can be placed in patients with a mild-moderate atrophic maxilla by using a CBCT

FALSE SEVERE atrophic maxilla

True or false: If the patient's mouth is open while doing a Water's projection, the maxillary sinus is seen superimposed over the palate

FALSE SPHENOID sinus

True or false: Contemporary CBCT machines uses flat/rectangular PSP detectors

FALSE Uses FLAT PANEL detectors

True or false: The floor of the nasal cavity or hard palate is seen as horizontal radiolucency in a panoramic radiograph

FALSE radiopacity!

In regard to panoramic distortions, lingually positioned canal is projected more inferiorly than when a canal is located buccally.

False. SUPERIORLY

True or false: The ideal radionuclide has a long half-life, emits γ rays but no charged particles, and is capable of binding to various pharmaceuticals.

False. Short half-life

True or false: Inherent artifacts are distortions or errors in an image not related to the subject being studied

False. These are image artifacts

True or false: Undersampling occurs when too many basis projections are provided for image.

False. Too few

True or false: In order to obtain the highest resolution image, one should take multiple small FOV images and stitch them together.

False. Unethical. One should use a larger FOV for region of interest

True or false. The Hounsfield scale applies to medical-grade CT scans as well as CBCT scans.

False. The Hounsfield scale applies to medical-grade CT scans but not to CBCT scans

What is a cephalostat used for?

Helps maintain constant relationship: skull, receptor + beam

Which three anatomical features are often double imaged?

Hyoid bone, epiglottis, and cervical spine.

Using ultrasonography, tissues producing a weak signal are said to be ___ and appear black. a. Anechoic b. Hypoechoic c. Hyperechoic

Hypoechoic

When using the tube shifting technique to localize a foreign body, the object moved in the same direction of the xray source. Is the foreign body on the buccal or the lingual?

Lingual

Pantomography is also know as what?

Panoramic imaging

When treatment planning growth and development in pedodontics and orthodontics, what radiographs are utilized?

Pantomography and cephalometric radiographs

What radiographs are utilized in detection of dental anomalies?

Pantomography and periapicals

What radiographs are utilized in detection of occult diseases, jaw pathosis, TM Joint, trauma, paranasal sinuses, implant placement?

Pantomography, CT, and MRI

You are assessing a panoramic radiograph and notice the incisors are wide and the condyles were cut off. What error likely occurred?

Patient was placed too far behind the SDP producing a bigger and wider image.

You are assessing a panoramic radiograph and notice the incisors are far too skinny. What error likely occurred?

Patient was placed too far in front of the SDP producing a smaller and narrower image.

A new patient with primary dentition presents to the office. You take selected PAs but cannot visualize the proximal surfaces. What other radiograph is indicated?

Posterior bitewings

What happens if a patient's mouth is open during a Water's Projection?

The sphenoid sinus is seen superimposed over the palate.

True or false: A narrow vertical beam is used in panoramic radiographs, unlike conventional intraoral radiography which uses a circular or rectangular beams

True

True or false: Extraoral radiographs use intensifying screens to convert x-ray photons to visible light

True

True or false: In the right angle technique, 2 radiographs (typically a PA and occlusal) are taken at right angles to one another to localize a foreign body

True

True or false: The goal of a lateral cephalometric projection to evaluate the relationship between the maxilla, mandible, and cranial base

True

True or false: The reconstructed volume of a CBCT is composed of 3 views, axial, coronal, and sagittal

True

True or false: The smaller the field of view (FOV), the higher the resolution

True

True or false: All of the following are ways CBCT can aid dental implantation: Bone quantity & quality; shape and anatomy; bone grafts and sinus lifting; Virtual implant placement; Template for guided surgery; Dynamic Navigational Surgery.

True.

True or false: Artifacts in panoramic radiographs are a limitation.

True.

True or false: CBCT aids in oral and maxillofacial diagnosis by being able to detect Stafne Defect and Surgical Ciliated Cyst of Maxilla

True.

True or false: CBCT has imaging protocol which is a set of technical exposure parameters for imaging that depend on specified purpose of the examination (i.e., task specific, correct FOV, voxel size)

True.

True or false: CBCT imaging can be reformatted and viewed in axial, sagittal and coronal, as well as cross-sectional planes.

True.

True or false: CBCT third party software can be used for virtual 3D treatment planning and/or surgery.

True.

True or false: Dentition should be separated but held together firmly during the CBCT scan; cotton rolls may help.

True.

True or false: FOV dimensions depend on detector size, ability to collimate the beam, and beam projection geometry.

True.

True or false: For a recall patient with periodontal disease, use clinical judgment as to need for any type of radiography, i.e., selected bitewings/periapical radiographs/FMX.

True.

True or false: Ghost images appear on the opposite side, superior, blurred and magnified.

True.

True or false: Hounsdield unit is a quantitative measure of radiodensity used in evaluating CT scans.

True.

True or false: If focal spot is increased, sharpness will be decreased but it can handle heat better.

True.

True or false: Image noise and poor soft tissue contrast are limitations of CBCT imaging.

True.

True or false: Less radiation is needed for extraoral imaging than intraoral, but intraoral has higher resolution.

True.

True or false: MRI is non-ionizing radiation.

True.

True or false: Most commonly used radionuclide is technetium 99m (99mTc) with half-life of 6 hours. It emits primarily 140 keV photons.

True.

True or false: New edentulous patients require individualized radiograph (panoramic) based on clinical signs and symptoms

True.

True or false: Patient motion can cause misregistration of data, which appear as double contours in the reconstructed image.

True.

True or false: Pre and post treatment CBCT images can be superimposed and assessed with "mesh" visualization.

True.

True or false: Regarding ultrasonography, current techniques permit echoes to be processed at a sufficiently rapid rate to allow perception of motion, referred as real-time imaging

True.

True or false: Uniformity of voxels means CBCT has superior dimensional accuracy in reconstruction process of raw data.

True.

True or false: Occlusal radiographs utilize the bisecting-angle technique.

True. Dr. Yang said this verbally on first slide of lecture

True or false: The floor of the nasal cavity or hard palate is seen as a horizontal radiopacity on panoramic radiographs.

True. Lower line is sharp and represents the junction between the lateral wall of the nasal cavity Upper line is more diffuse and represents the junction on the opposite side Upper line is a ghost image I believe

True or false: CBCT may be better than MD CT for TMJ assessment because we can see the condyles better.

True.s

What is the CT number for bone? a. +400 to +1000 b. +40 to +80 c. 0 d. -60 to -100 e. -400 to -600 f. -1000

a. +400 to +1000

Parallel to the transverse plane. a. Axial slice b. Sagittal slice c. Coronal slice

a. Axial slice Bird's eye view One of Dr. Badi's favorite scans because it gives an overall pictures of what is going on

As an x-ray beam passes through an object, lower energy photons are absorbed in preference to higher energy photons. a. Beam hardening b. Cupping artifacts c. Streaks and dark bands

a. Beam hardening (cupping artifact + streaks)

In CBCT, internal structures of the body attenuate X-rays proportionally to their coefficient of attenuation "mu"; Intensity captured by detectors depends on the attenuation pattern of internal tissues. a. Both statements are true b. Statement 1 is true, statement 2 is false c. Statement 1 is false, statement 2 is true d. Both statements are false

a. Both statements are true

Real images: Objects that lie between the center of rotation and the receptor form a real image. Double images: Objects that lie posterior to the center of rotation and that are intercepted twice by the x-ray beam form double image. a. Both statements are true b. Statement 1 is true, statement 2 is false c. Statement 1 is false, statement 2 is true d. Both statements are false

a. Both statements are true

T1-weighted images are for anatomic detail structures; T2-weighted images are for pathology. a. Both statements are true b. Statement 1 is true, statement 2 is false c. Statement 1 is false, statement 2 is true d. Both statements are false

a. Both statements are true

In CBCT, software programs reconstruct the cross-sectional anatomy by using sophisticated algorithms to generate volumetric images; The goal of the reconstruction is to give to each pixel its right gray level. a. Both statements are true b. Statement 1 is true, statement 2 is false c. Statement 1 is false, statement 2 is true d. Both statements are false

a. Both statements are true Filtered back projection algorithm is commonly used

PET images are often fused with ___ to facilitate anatomic localization of radionuclide. a. CT b. MRI c. Nuclear medicine d. Ultrasonography

a. CT PET/CT combination has been shown to be quite helpful in staging and treatment planning of squamous cell carcinoma (SCC) in head and neck

Central point of external auditory canal to outer canthus of the eye: a. Canthomeatal line b. Frankfurt plane

a. Canthomeatal line

Match the following: Air Fat Water Circulating Blood Bone a. +44 b. +700 c. 0 d. -50 to -120 e. -1000

a. Circulating Blood b. Bone c. Water d. Fat e. Air

Which of the following projections is take in the sagittal (median) plane (select all that apply)? a. Lateral Cephalometric b. Submentovertex c. Waters d. Posteroanterior (PA) Cephalometric e. Reverse-Towne f. Panoramic

a. Lateral Cephalometric

Evaluate relationship between maxilla, mandible + cranial base (oral and facial structures). Monitor progress or treatment and treatment outcomes. a. Lateral Cephalometric Projection b. PA Cephalometric Projection c. Submentovertex Projection d. Water's Projection e. Reverse-Towne Projection

a. Lateral Cephalometric Projection

Most commonly used extraoral projection in dentistry? a. Lateral Cephalometric Projection b. PA Cephalometric Projection c. Submentovertex Projection d. Water's Projection e. Reverse-Towne Projection

a. Lateral Cephalometric Projection

Skeletal, dental + soft tissue landmarks delineate lines, planes, angles , distance -> generate measurements to classify craniofacial morphology. a. Lateral Cephalometric Projection b. PA Cephalometric Projection c. Submentovertex Projection d. Water's Projection e. Reverse-Towne Projection

a. Lateral Cephalometric Projection

Patient placed with left side towards receptor. Receptor parallel to mid sagittal plane. X-ray beam is perpendicular to the midsagittal plane. Wedge filter placed on anterior of beam for visualization of soft tissue. a. Lateral Cephalometric Projection b. PA Cephalometric Projection c. Submentovertex Projection d. Water's Projection e. Reverse-Towne Projection

a. Lateral Cephalometric Projection Can see all of the sinuses, skull base, auditory canal, cervical spine, epiglottis, airway space, hyoid bone, etc.

Non ionization radiation No metal artifact Better soft tissue density a. MRI b. CT

a. MRI

Which is an intermediate signal for T1- and T2-weighted images? a. Muscle b. Water c. Bone marrow d. CSF e. Cortical bone

a. Muscle

Objects that lie between the center of rotation and the receptor. a. Real image b. Double image c. Ghost image

a. Real image

Diffracted photons interact with matter: a. Scatter b. Partial volume averaging c. Cone-beam effect

a. Scatter

The time of repetition (TR) and time of echo (TE) for T1-weighted image: a. Short, short b. Short, long c. Long, short d. Long, long

a. Short, short

Which object localization technique uses two radiographs of an object at different angles and employs the "SLOB" acronym? a. Tube shift technique b. Right-angle technique

a. Tube shift technique

Which of the following is a method to minimize loss of image clarity? a. Use as small a focal spot as practical b. Minimize distance from the focal spot to the object c. Increase distance from the object to the film/sensor d. All of the above

a. Use as small a focal spot as practical b. Increase distance c. Minimize distance

What is the CT number for soft tissue? a. +400 to +1000 b. +40 to +80 c. 0 d. -60 to -100 e. -400 to -600 f. -1000

b. +40 to +80

What is the range of CT numbers? a. +400 to +1000 b. -1000 to +1000 c. -500 to +500 d. -400 to +1000

b. -1000 to +1000

Canthomeatal line forms a ___-degree angle with the Frankfurt plane? a. 5 b. 10 c. 15 d. 20

b. 10

Cephalometric and skull views require ___ x ___ inch (20 x 25 cm) receptor. a. 4 x 8 b. 8 x 10 c. 10 x 12 d. 8 x 12

b. 8 x 10

Film/sensor is close to teeth, but not parallel to the long axis of teeth. Central ray perpendicular to an imaginary plane that bisects the angle b/w teeth & film/sensor. a. Paralleling technique b. Bisecting-angle technique

b. Bisecting-angle technique

Ionization radiation Metal artifact Better bone density a. MRI b. CT

b. CT

Distortion of metallic structures as a result of differential absorption. a. Beam hardening b. Cupping artifacts c. Streaks and dark bands

b. Cupping artifacts

Which of the following is incorrect regarding the bisecting angle technique? a. There is dimensional distortion with inherent anatomic inaccuracy. b. Distortion tends to decrease along the image toward to the apex c. Teeth foreshortened or elongated d. All of there above are correct

b. Distortion tends to decrease along the image toward to the apex INCREASE

Objects that lie posterior to the center of rotation and that are intercepted twice by the x-ray beam form double image. a. Real image b. Double image c. Ghost image

b. Double image

External auditory canal to infraorbital of the eye: a. Canthomeatal line b. Frankfurt plane

b. Frankfurt plane

Which of the following is not true regarding panoramic compared with a full-mouth examination? a. Broad coverage of facial bones and teeth b. Higher radiation dose c. Ease of panoramic radiographic technique d. Can be used in patients with trismus or in patients who cannot tolerate intraoral radiography e. Quick and convenient radiographic technique f. Useful visual aid in patient education and case presentation

b. Higher radiation dose Lower radiation for panoramic

Artifacts that arise from limitations in the physical processes of CBCT technology. a. Image artifacts b. Inherent artifacts

b. Inherent artifacts

What size FOV would you use to view an arch? a. Small FOV b. Medium FOV c. Large FOV

b. Medium FOV Small - quadrant or less Large - more than 15 cm cranium to cervical spine

Evaluation of facial asymmetries + assessment of orthognathic surgery outcomes: midline or mandibular-maxillary relationship. Monitor progress of treatment and treatment outcomes. a. Lateral Cephalometric Projection b. PA Cephalometric Projection c. Submentovertex Projection d. Water's Projection e. Reverse-Towne Projection

b. PA Cephalometric Projection

Image receptor is in front of patient, perpendicular to the midsagittal plane and parallel to the coronal plane. Patient positioning: Canthomeatal line forms a 10 degree angle with horizontal plane. Frankfurt plane is perpendicular to the image receptor. a. Lateral Cephalometric Projection b. PA Cephalometric Projection c. Submentovertex Projection d. Water's Projection e. Reverse-Towne Projection

b. PA Cephalometric Projection

Second most common skull radiograph used in dentistry: a. Lateral Cephalometric Projection b. PA Cephalometric Projection c. Submentovertex Projection d. Water's Projection e. Reverse-Towne Projection

b. PA Cephalometric Projection

Selected voxel size of the scan is larger than the size of the object being imaged. 1 mm voxel may contain bone and soft tissue. a. Scatter b. Partial volume averaging c. Cone-beam effect

b. Partial volume averaging

Parallel to the median plane of the patient. a. Axial slice b. Sagittal slice c. Coronal slice

b. Sagittal slice Airways spaces, sinuses, palate, tongue at roof of mouth

Gray-scale & power Doppler US images show an inhomogeneous parotid gland with multiple small, oval, hypoechoic areas (arrowheads) & increased blood flow. What is your diagnosis? a. Sialolith b. Sjogren's syndrome c. Atherosclerotic carotid artery

b. Sjogren's syndrome

Which of the following projections is take in the axial (horizontal) plane (select all that apply)? a. Lateral Cephalometric b. Submentovertex c. Waters d. Posteroanterior (PA) Cephalometric e. Reverse-Towne f. Panoramic

b. Submentovertex

Which step of CBCT imaging is incorrect? a. X-ray source produces cone-shaped beam that irradiates a patient's mouth and jaw as the arm rotates. b. Tungsten scintillator converts x-rays into visible light. c. Photosensitive pixels convert scintillator's light into electrical signals. On-chip circuitry turns electrical signals into digital output. d. Digital data is sent to a computer for 3D reconstruction. e. All of the above are correct

b. Tungsten scintillator converts x-rays into visible light. Cesium iodide scintillator Flat panel sensors used in all modern systems

What is the CT number for water? a. +400 to +1000 b. +40 to +80 c. 0 d. -60 to -100 e. -400 to -600 f. -1000

c. 0

Intraoral receptors have progressed from C-speed to D-speed to E-speed to F-speed to digital; Extraoral receptors have progressed from par-speed to rare earths to digital. a. Statement one is true, statement two is false b. Statement one is false, statement two is true c. Both statements are true d. Both statements are false

c. Both statements are true

Which is false regarding paralleling technique? a. It is the preferred technique b. Film or sensor is not close to teeth, but parallel to the long axis of teeth c. Central rays are parallel to the long axis of teeth and film/sensor d. Minimal distortion with anatomic accuracy e. All of the above are true

c. Central rays are parallel to the long axis of teeth and film/sensor PERPENDICULAR

Artifacts in the peripheral portions of the scan volume. a. Scatter b. Partial volume averaging c. Cone-beam effect

c. Cone-beam effect

Parallel to the frontal plane. a. Axial slice b. Sagittal slice c. Coronal slice

c. Coronal slice

Objects are located between the x-ray source and the center of rotation. a. Real image b. Double image c. Ghost image

c. Ghost image Ghost images appear on the opposite side, superior, blurred and magnified

Using ultrasonography, tissues producing intense signals are said to be ___ and appear black. a. Anechoic b. Hypoechoic c. Hyperechoic

c. Hyperechoic

The time of repetition (TR) and time of echo (TE) for proton density: a. Short, short b. Short, long c. Long, short d. Long, long

c. Long, short

Radionuclide imaging uses radioactive atoms or molecules that emit γ (gamma) rays. a. CT b. MRI c. Nuclear medicine d. PET e. Ultrasonography

c. Nuclear medicine

Used for diagnosis and follow-up of metastatic disease, bone tumors, and infection. a. CT b. MRI c. Nuclear medicine d. PET e. Ultrasonography

c. Nuclear medicine

Present between two dense objects, create extinction or missing value artifacts a. Beam hardening b. Cupping artifacts c. Streaks and dark bands

c. Streaks and dark bands

Image receptor is positioned parallel to the patient's transverse plane and perpendicular to the midsagittal and coronal planes. Central beam perpendicular to the receptor. Patient's neck is extended as far backward as possible, with the canthomeatal line parallel to the image receptor. a. Lateral Cephalometric Projection b. PA Cephalometric Projection c. Submentovertex Projection d. Water's Projection e. Reverse-Towne Projection

c. Submentovertex Projection Good for zygomatic arch fractures and base of skull lesions

Select the false statement. a. Detail of CBCT image is determined by voxels. b. CBCT units provide isotropic (equal in all dimensions) voxels. c. The larger the voxel size the higher the resolution. d. Principal determinants of voxel size in a CBCT image are the matrix and pixel size of the detector. e. Resolution of anisotropic voxels, found in conventional CT, is a function of slice pitch and gantry motion. f. Isotropic voxels produce sub-millimeter resolution from 0.4 - 0.08mm.

c. The larger the voxel size the higher the resolution. Smaller voxel --> higher resolution

Which of the following projections is take in the coronal (frontal) plane (select all that apply)? a. Lateral Cephalometric b. Submentovertex c. Waters d. Posteroanterior (PA) Cephalometric e. Reverse-Towne f. Panoramic

c. Waters d. Posteroanterior (PA) e. Cephalometric f. Reverse-Towne

What is the CT number for fat? a. +400 to +1000 b. +40 to +80 c. 0 d. -60 to -100 e. -400 to -600 f. -1000

d. -60 to -100

12 year old with mixed dentition presents to the office. What radiographs are indicated? a. Posterior bitewings with panoramic radiograph b. Posterior bitewings and selected periapical radiographs (panoramic is not available). c. CBCT d. A and B e. All of the above

d. A and B

In regard to sinus grafting procedures, compared to panoramic imaging, CBCT shows: a. Higher detection rate of sinus mucosal disease b. Increase in surgical confidence c. Better prediction of complications d. All of the above

d. All of the above

Inherent artifacts are due to: a. Scatter b. Partial volume averaging c. Cone-beam effect d. All of the above

d. All of the above

New patient presents with permanent dentition. What radiographs are indicated? a. Full mouth intraoral radiographs (FMX) b. Posterior bitewings with panoramic radiograph c. Posterior bitewings and selected periapical radiographs. d. All of the above

d. All of the above

Select the true statement regarding panoramic imaging. a. Images are taken with a slight negative angulation (angled slightly upward) b. The angulation allows for x-ray beam to pass inferior to the skull base c. Angle is about -4 to -7 degrees d. All of the above

d. All of the above

Select the true statement: a. CBCT is an effective submillimeter diagnostic imaging technology enabling visualization of osseous structures at lower doses compared to MDCT imaging b. Although easy to perform CBCT should be considered as an adjunctive diagnostic modality to history and clinical examination c. Imaging should be task specific with scan factor protocol adjusted to optimize image display and minimize patient dose d. All of the above

d. All of the above

Select the true statement: a. Use CBCT immediately postoperatively only if there is implant mobility or altered sensation, esp in posterior mandible b. Do not use CBCT for periodic review if asymptomatic c. All CBCT volumes, regardless of clinical application, should be systematically evaluated for signs of abnormalities. d. All of the above

d. All of the above

Which is an advantage of limiting FOV? a. Limit radiation exposure b. Artifacts reduction c. Smaller voxel size -> higher resolution d. All of the above

d. All of the above

Which is true regarding PET imaging? a. PET imaging is a more advanced imaging modality in nuclear medicine b. Sensitivity nearly 100 times of a gamma camera c. Commonly used radionuclides (C, N, O, F) are isotopes of elements that occur naturally in organic molecules d. All of the above

d. All of the above

Which of the following is true? a. Ability of CBCT imaging to display differences in attenuation is related to the ability of the detector to reveal subtle contrast differences aka bit depth : no. of shades of gray b. cGray scale or intensity of each pixel in all CT machines is related to the intensity of photons that reach the detector c. Current CBCT units use 12 bits or greater d. All of the above

d. All of the above

The time of repetition (TR) and time of echo (TE) for T2-weighted image: a. Short, short b. Short, long c. Long, short d. Long, long

d. Long, long

Useful in skeletal imaging for assessing primary bone tumors, locating metastases in bone, and detecting osteomyelitis. a. CT b. MRI c. Nuclear medicine d. PET e. Ultrasonography

d. PET Fluorodeoxyglucose (FDG) is a radiopharmaceutical commonly used for studying glucose use in the brain and heart and to look for cancer metastases.

Image receptor is placed in front of the patient and perpendicular to the midsagittal plane. Beam perpendicular to image receptor. Patient's head is tilted upward so that the canthomeatal line forms a 37-degree angle with the image receptor. a. Lateral Cephalometric Projection b. PA Cephalometric Projection c. Submentovertex Projection d. Water's Projection e. Reverse-Towne Projection

d. Water's Projection Good for assessing paranasal sinuses

Which is false regarding panoramic imaging? a. Selectively images a specific body layer blurring images on other planes. b. Rotating a narrow beam of radiation in horizontal plane around an invisible rotational axis that is positioned intraorally. c. Narrow vertical beam is used compared with circular or rectangular beam in conventional intraoral radiography. e. Focal trough or sharply depicted plane (SDP) is a zone in which the included objects are displayed clearly

d. X-ray tube rotates around the patient's head in one direction while the receptor rotates in the same direction Receptor rotates in opposite direction

What is the CT number for lung? a. +400 to +1000 b. +40 to +80 c. 0 d. -60 to -100 e. -400 to -600 f. -1000

e. -400 to -600

CBCT images inherently have more artifacts than MDCT images because: a. Lower energy spectra used b. Cone-beam geometry c. Cone-beam divergence, scatter d. Noise e. All of the above

e. All of the above

CBCT should be considered for: a. Sinus augmentation b. Block or particulate bone grafting c. Ramus or symphysis grafting d. Assessment of impacted teeth & prior traumatic injury e. All of the above

e. All of the above

MRIs are used for: a. Internal derangements of the TMJ b. Diagnosis of Soft tissue neoplasms c. Infectious diseases d. Pathology related to cranial nerves e. All of the above

e. All of the above

Radiographic examination is used to: a. Determine degree, extent of disease b. Establish a diagnosis & treatment planning c. Monitor a disease process (follow-up) d. Medical and legal documentation e. All of the above

e. All of the above

Select the true statement: a. AAOMR recommends that cross-sectional imaging be used for the assessment of all dental implant sites b. CBCT is the imaging method of choice for gaining this information c. Panoramic and periapical as initial screen d. Postoperative usually follow-up by periapical radiography, may be panoramic e. All of the above

e. All of the above

Which statement is true? a. CBCT units will capture about several hundred views around the patient by pulsing the x-rays on and off on each degree b. One Rotation 180 to 360 degrees arc (less than 20 seconds) c. Individual images are referred to as basis images d. Complete series of images is referred to as the projection data e. All of the above

e. All of the above

Which statement is true? a. CBCT provide 3D imaging, but has limitations. b. CBCT not be used routinely for ENDO diagnosis or screening in absence of signs and symptoms c. CBCT use only when need cannot be met by lower dose 2D radiography d. FOV should only slightly exceed anatomy of interest e. All of the above

e. All of the above Possible higher radiation dose, potential artifact generation, high levels of scatter and noise, variations in dose distribution

Which is false regarding CTs vs. conventional films? a. CTs eliminate superimposition of structures b. CTs have higher contrast resolution c. CTs have multiplanar imaging (2D and 3D imaging reconstruction) d. CTs can differentiate soft tissues e. CTs have lower radiation dose f. CTs are more expensive g. CTs have metallic artifact

e. CTs have lower radiation dose HIGHER

Which is a low signal for T1- and T2-weighted images? a. Fat b. Water c. Bone marrow d. CSF e. Cortical bone

e. Cortical bone

Which of the following is/are not indications for panoramic imaging (select all that apply)? a. Overall evaluation of dentition b. Examine for intraosseous pathology: cysts, tumors or infections c. Gross evaluation of temporomandibular joints d. Evaluation of position of impacted teeth e. Evaluation of extensive caries f. Evaluation of eruption of permanent dentition g. Dentomaxillofacial trauma: trismu h. Developmental disturbances of maxillofacial skeleton

e. Evaluation of extensive caries

Which is false regarding the paralleling technique? a. Film/sensor must be parallel to the tooth long axis b. Central rays must be perpendicular to film/sensor c. Central rays must be perpendicular to teeth d. There is an increased focal spot-film/sensor distance e. Film/sensor holder & beam alignment device are not required

e. Film/sensor holder & beam alignment device are not required XCP is required

Which of the following is not a common occlusal radiograph projection? a. Maxillary Anterior b. Maxillary Standard c. Maxillary Lateral d. Mandibular Anterior e. Mandibular Lateral f. Mandibular True

e. Mandibular Lateral

Image receptor is placed in front of the patient, perpendicular to the midsagittal plane and parallel to the coronal plane. Patient's head is tilted downward so that the canthomeatal line forms a -30 degree angle with the image receptor. Patient's mouth is opened so that the condylar heads are located inferior to the articular eminence (enhance visualization of condyles). a. Lateral Cephalometric Projection b. PA Cephalometric Projection c. Submentovertex Projection d. Water's Projection e. Reverse-Towne Projection

e. Reverse-Towne Projection Good for assessing TMJ fractures and disorders

Commonly used in evaluation of neoplasms in thyroid, parathyroid, salivary glands, or lymph nodes; stones in salivary glands or ducts; Sjögren's syndrome; vessels of neck, such as carotid artery for atherosclerotic plaques. a. CT b. MRI c. Nuclear medicine d. PET e. Ultrasonography

e. Ultrasonography

Based on sound waves that acquires images in real time without use of ionizing radiation. a. CT b. MRI c. Nuclear medicine d. PET e. Ultrasonography

e. Ultrasonography Diagnostic ultrasonography uses vibratory frequencies in range of 1 to 20 MHz Sonic waves that reflect (echo) toward the transducer, which produces an electrical signal that is amplified, processed, and ultimately displayed as an image on monitor

What is the CT number for air? a. +400 to +1000 b. +40 to +80 c. 0 d. -60 to -100 e. -400 to -600 f. -1000

f. -1000

CT scans produce which view(s) (select all that apply). a. Axial b. Sagittal c. Transverse d. Coronal e. A, B, and C f. A, C, and D g. All o

f. A, C, and D

Which is true regarding CT imaging? a. CT image is reconstructed by computer b. Recorded as a matrix of individual blocks called voxels (volume element) c. Each square of the image matrix is termed a pixel (picture element) d. Each pixel assigned a CT number (Hounsfield unit) e. CT number proportion to attenuation of x-ray beam f. All of the above

f. All of the above

Which of the following is an application for occlusal radiographs? a. Large lesion: tumor or cyst b. Sialolith c. Foreign object location d. Fracture e. Infection f. All of the above

f. All of the above

CT is used for all of the following, except? a. Diagnosis of maxillofacial complex (trauma, tumor, inflammation) b. Salivary gland diseases c. TMJ evaluation d. 2 dimensional and 3 dimensional reconstructions for dental implants e. Cranio-facial reconstructive surgery f. Caries detection and periodontal destruction

f. Caries detection and periodontal destruction

CBCT can be applied to which of the following: a. Oral & Maxillofacial Diagnosis c. Dental Implants c. TMJ Assessment d. Endodontic & Orthodontic Treatment Planning e. Oral & Maxillofacial Surgery Procedures f. Sleep Apnea g. All of the above

g. All of the above

The sensor is not close to the teeth but parallel to the long axis of the tooth in the paralleling technique. The sensor is close to the teeth but not parallel to the long axis of the tooth in the bisecting angle technique A. Both statements are true B. Statement 1 is true, statement 2 is false C. Both statements are false D. Statement 1 is false, statement 2 is true

A. Both statements are true

Patient is placed with the left side towards the receptor. The receptor parallels the midsagittal plane. The X-ray beam is perpendicular to the midsagittal plane. A wedge filter is placed on the anterior of the beam to visualize soft tissue A. Lateral cephalometric projection B. Posteroanterior cephalometric projection C. Submentovertex projection D. Water's projection E. Reverse towne projection

A. Lateral cephalometric projection

Objects that lie in between the center of rotation and the receptor form a ... A. Real image B. Double image C. Ghost image

A. Real image

What step of the CBCT is this step describing? Software programs reconstruct the cross sectional anatomy by using sophisticated algorithms to generate the volumetric. The filtered back projection algorithm is commonly used. The goal of this step is to give each pixel its grey level. A. Reconstruction B. Visualization C. Acquisition

A. Reconstruction

For child, adolescent, and adult recall patients with NO clinical caries or increased risk for caries, what are the recall schedules for radiographs (three answers)?

Child - posterior bitewings 12-24 months if proximal surfaces cannot be seen Adolescent - posterior bitewings 18-36 months Adults - posterior bitewings 24-36 months

For child and adult recall patients with clinical caries or increased risk for caries, what are the recall schedules for radiographs (two answers)?

Child - posterior bitewings 6-12 months Adult - posterior bitewings 6-18 months