Diagnostic Imaging
Anything below what Hounsfield unit is displayed as black on CT imaging?
- 750 HU Anything below -750 HU will be seen as black on the CT image. Anything that falls between -750 and 1250 will be visible as shades of gray.
What is the typical wavelength of a medical x-ray?
0.05-0.01 nm A wavelength of an x-ray is measured in nanometers (nm). A nanometer is equal to one millionth of a millimeter. The typical wavelength of a medical x-ray is 0.05-0.01 nanometers (nm). The choices millimeter, meter, and decimeter are the incorrect units.
Modern CT scanners use multislice technology and are able to acquire image slices thinner than which of the following sizes?
1 mm
Pulse wave imaging can detect velocities up to a maximum of __________ m/s.
1.4 Pulse wave imaging can detect a maximum velocity of 1.4 m/s. Any velocity that exceeds 1.4 m/s starts to alias and cannot be measured accurately.
What size of power outlet is required to run a digital dental unit?
110 V A 110-V power outlet is required to operate a dental radiograph unit. The standard preset to operate a dental unit is 70 kV and 8 mA. 110 kV is incorrect for a power outlet.
To what level of kV radiation are most lead aprons effective?
125 kV Lead aprons are designed to be effective for ≤125 kV of radiation. The levels of 50 kV, 70 kV, and 90 kV are all typical x-ray exposure doses in which the use of a lead apron is needed for protection.
Which of the following Hounsfield units on CT imaging appears as white?
1260 HU Anything above 1250 HU in CT imaging appears as white on the image. Black colors appear at the -755 HU level. Different shades of gray appear between -750 and 1250 HU, therefore 120 HU and 1200 HU both appear as shades of gray.
At what age in foals does the closure of the proximal growth plate of P2 occur?
18-30 weeks Closure of the proximal growth plate of P2 occurs between 18-30 weeks. The first radiographic appearance of the crena occurs between 4-22 weeks. The closure of the proximal growth plate of P1 occurs between 22-38 weeks. The closure of the distal growth plate of MC3 occurs between 18-38 weeks.
How long does it take for barium sulfate to travel from the stomach to the colon?
3 hours
How long should veterinary facilities maintain dosimetry reports?
30 years Dosimetry reports should be kept for a minimum of 30 years in case any medical issues arise regarding team members that might have been exposed. Harmful effects of radiation can take several years to arise; therefore, dosimetry reports should be kept for ≥30 years.
A computer tomography x-ray tube can rotate how many degrees?
360 degrees A computed tomography x-ray tube rotates 360 degrees around the patient. A dental x-ray unit can rotate in a range ≤270 degrees. A stationary x-ray machine does not rotate at all.
When do fetal skeletons of small animals become visible on x-ray?
42-45 days
Which repetition time shows the T1 decay response of the tissues using MRI?
546 ms A lower repetition time of ≤699 ms shows the T1 decay response of the tissues. A higher repetition time of ≤1500 ms shows the T2 decay response and changes the contrast of the images.
MRI machines produce noise in which of the following ranges?
60-90 dB MRI machines are acoustically very loud and reach noise levels between 60 dB and 90 dB. Ear shielding is necessary for patients and for anyone staying in the MRI room during a scan.
When using computed tomography, what Hounsfield unit does blood have?
80 HU Blood is read at 80 HU in computed tomography. Fat reads as -50 HU using CT, and calcium reads as 160 HU using CT imaging.
In the equation Z = pV used in ultrasound, what does the letter Z represent?
Acoustic impedance
Before imaging the coffin bone in horses, which of the following tasks should be performed in preparation? A - Hoof should be trimmed to the new sole level B - The horseshoes need to be removed C - The sulcus should be packed with radiolucent material D - All of the above
All of the above
Which of the following can occur if DNA is affected by radiation? A - Cell death B - Cell damage may be obvious, with portions of the DNA compromised C - Cell may display no immediate effects, but damage may have occurred internally that will affect the individual later, when mitosis occurs Incorrect D - All of the above
All of the above
Which of the following could be considered as negative-contrast agents used in radiography? A - Oxygen B - Air C - Carbon dioxide D - All of the above
All of the above
Which of the following is considered to be a cardinal rule for radiation protection? A - Distance B - Time C - Shielding D - All of the above
All of the above
Which parts of a patient's body are considered radioactive after they have received the radioisotope? A - Skin B - Hair C - Waste products D - All of the above
All of the above After a patient has received the radioisotope, the entire body as well as the waste products are considered radioactive for at least 48 hours.
Which of the following factors should all personnel understand about MRI machines? A - No loose metallic objects can be near the machine B - It consists of a strong magnetic field C - The magnet is always on D - Every patient/employee should be screened for safety purposes E - All of the above
All of the above All personnel working in a facility that contains an MRI machine should be aware of the following: every patient/employee should be screened for safety purposes, no loose metallic objects can be near the machines, the MRI consists of a strong magnetic field, and the magnet is always on.
For digital radiography, what does the postprocessing step of image manipulation allow? A - Magnification B - Rotation C - Contrast adjustment D - All of the above
All of the above Postprocessing manipulation is a huge advantage of using digital x-ray because it allows for magnification, rotation, and contrast adjustment.
All of the following people are allowed to view individual dosimetry reports, except: A - OSHA inspector B - Owner of the practice C - Only the employee exposed D - All team members
All team members
Which contrast is commonly used for GI studies when perforation is not suspected?
Barium sulfate
Which time frame is the most critical for limiting radiation exposure to an unborn fetus of an employee?
Between 2 and 10 weeks gestation
Which of the following types of tissue absorb the most radiation?
Bone Bone is denser than soft tissue and fat; therefore, it efficiently absorbs more radiation and prevents the image receptor from exposure. This explains why bone appears white on x-ray.
IV contrast used with CT imaging will help to view all of the following, except: A - Veins B - Arteries C - Bone marrow D - Infection of the extremities
Bone marrow
Which of the following image receptors is used in dental imaging? A - Film B - Phosphor plates C - Neither D - Both
Both Dental imaging uses film and small phosphor plates as image receptors. The phosphor plates are used both for direct digital imaging and for computerized imaging.
Which particles have high linear energy transfer (LET) with low penetrability? A - Alpha particles B - Beta particles C - Gamma particles D - Both a and b
Both a and b Alpha and beta particles both have high linear energy transfer (LET) and low penetrability. The term LET describes the amount of energy imparted to the target. Gamma rays have low LET and high penetrability.
Which of the following correctly describes a CT image? A - A two-dimensional image B - A matrix of pixel or picture elements C - A three-dimensional image D - A matrix of voxels E - Both c and d F - Both a and b
Both c and d A CT image is a three-dimensional image or a matrix of voxels that includes the third dimension of depth. A radiograph is a two-dimensional image or a matrix of pixels or picture elements.
If pneumonia is suspected in small animals, which of the following radiographic views should be performed?
Both lateral views and ventrodorsal view
Radiographs of long bones must include which of the following?
Both the joint proximal and the joint distal to the long bone
Which of the following allows for measurements of very high blood flow velocities in ultrasound?
CW Doppler
For a lateral avian view, where would the left wings and limbs be positioned?
Caudally to the right wings and limbs
Which of the following is the best restraint to use in avian radiography?
Chemical restraint For avian radiography, chemical restraint is the most common form of restraint to avoid injury to the patient. Manual restraint consists of gloved hands to hold the patient, which is not possible in most cases (gloved hands should never enter into the direct radiation beam). Physical restraint devices can be used, such as soft nylon ropes, paper tape, IV tubing, or cardboard, but these can only be used in combination with chemical restraints.
Lead shutters installed in the tube head of the x-ray machine are referred to as:
Collimators
A feature of digital radiography that is related to the bit depth of each pixel and the software that accompanies the digital-imaging system is referred to as which of the following?
Contrast optimization
For an avian lateral view, where should the dependent limb be placed compared to the contralateral limb?
Cranial For obtaining an avian lateral view, the dependent limb should be cranial to the contralateral limb. Moving the limbs in a lateral or medial position is not ideal in a lateral x-ray. Having the limbs superimposed makes it difficult to distinguish one from the other.
Digital radiography, CT, MRI, and ultrasound are stored using a universally accepted format known as?
DICOM
How does cerebrospinal fluid appear on a true T1-weighted image of MRI?
Different shades of gray Cerebrospinal fluid has a low signal intensity on a true T1-weighted image and appears black. Fat and skin have a high signal intensity and appear bright or white. Between the low and high signal intensities are different shades of gray.
Which of the following best describes the use for Doppler ultrasound?
Doppler is used to image the flow of blood and other liquids as well as to measure their velocity
To obtain a craniocaudal view of the tibia of a small animal, that patient should be in which of the following positions?
Dorsal recumbency
Meters to measure the rate of exposure is also known as:
Dosimeter
Which of the following is not an advantage of digital x-ray versus analog x-ray?
Elimination of damaging radiation A digital x-ray includes numerous advantages over analog x-ray, such as elimination of the darkroom, image postprocessing capabilities, exposure latitude and contract optimization, and consolidated image storage. Digital x-ray still uses radiation to obtain an x-ray, and all proper precautions should still be considered.
How often should x-ray equipment in a veterinarian's office be tested?
Every 2 years Per OSHA guidelines, it is recommended that x-ray equipment within a veterinarian's office should be tested every 2 years. This testing includes the accuracy of kilovoltage, half-value layer, milliampere linearity, reproducibility, timer accuracy, and collimator accuracy.
Which of the following will cause a fogged film?
Exposure to excessive scatter radiation A fogged film can be caused by exposure to excessive scatter radiation. Chemical spills on the screen as well as foreign material between the film and the screen can cause white areas. Film exposure resulting from static electricity causes black crescents or lines.
Which type of monitoring badge is the most common method of monitoring ionizing radiation?
Film badges
Which radiographic view provides the best accuracy for detecting carpal fractures in horses?
Flexed lateral view
Which of the following imaging modalities can cause radiation burns if the unit is too close to the skin and remains in exposure mode for too long?
Fluoroscopy
What causes grid lines on the entire film?
Focal-film distance not being in the range of the grid's focus
What occurs when the object is not parallel to the recording surface of an x-ray?
Foreshortening
What does MRI require to highlight injections, tumors, or vascular disease?
Gadolinium MRI requires the use of a contrast agent known as gadolinium, a paramagnetic, to highlight injection, tumors, or vascular disease. Iodine and barium contrast are both used in CT imaging.
Which of the following is not considered a physical restraint?
Gloved hands Gloved hands are considered as a form of manual restraint when obtaining x-rays. Physical restraints used to obtain x-rays are tape, radiolucent Plexiglas, foam pads, wooden blocks, and cardboard boxes.
An unossified carpal or tarsal bone describes which grade level on the ossification index for newborn foals?
Grade 1 A grade level 1 for the carpal and tarsal ossification index of newborn foals is described as an unossified carpal and tarsal bone. A grade 2 is described as the partial ossification of carpal and tarsal bones. A grade 3 describes all carpal or tarsal bones mineralized. A grade 4 describes the carpal and tarsal bones fully mineralized.
Which grade level on the ossification index for newborn foals does a closed metacarpal and metatarsal physes describe?
Grade 4 Closed metacarpal and metatarsal physes describe a grade level 4. An open proximal 3rd metacarpal or metatarsal growth plate describes grade level 2. A closed proximal 3rd metacarpal or metatarsal growth plate describes a grade level 3.
Which of the following locations is best for storing a dosimeter badge?
In a dry, cool place away from the x-ray room
Which of the following is not a form of barium sulfate that can be administered to patients?
Injectable Barium sulfate preparations are manufactured in the form of powders, colloid suspension, and pastes, and they are for oral use only. The barium sulfate preparation is not injectable.
How is gadolinium that is used in MRI excreted from the body?
Kidneys
The ability to distinguish between two objects that are adjacent to each other, yet perpendicular to the sound wave in ultrasound, is described as:
Lateral resolution
A grid is a series of thin, linear strips made of alternating radiodense and radiolucent material. Of what are the radiodense strips made?
Lead
Which of the following causes a black irregular border on one end of the film?
Light exposure while still in the box in advance of exposure A black irregular border on one end of the film is caused by light exposure while still in the box before being processed. Film that has expired, or exposure to radiation while still in storage, will cause a fogged film. Rough handling of the film before exposure will cause black crescents or lines.
Scatter radiation has a ____________ wavelength than the primary beam used in an x-ray.
Longer
Which imaging modality is superior for demonstrating the brain and spinal cord?
MRI
Which of the following terms correctly corresponds with the phrase toward the median plane?
Medial Medial refers to toward the median plane. Lateral refers to away from the median plane. Anterior refers to toward the ventral or front surface. Posterior refers to toward the dorsal or back surface.
To perform an ultrasound in the intercostal region, which transducer would be ideal?
Microconvex probe A microconvex probe is the ideal probe when performing an exam through the intercostal view because of the smaller footprint size and the spread of the wide-angle view. The linear probe is appropriate for high-resolution imaging for fine details. The phased array is useful in cardiac studies.
How does the adjacent bone density appear in fresh carpal chips in horses?
Normal In the presence of fresh carpal chips in horses, the surrounding bone density appears normal on x-ray. In old carpal chips, the adjacent bone density appears decreased.
For a mediolateral view of the tarsal joint of a horse, the cassette should be placed in which position?
On the lateral surface
Which of the following could cause a false diagnosis of a pneumothorax on a radiograph?
Overexposure of film A false diagnosis of pneumothorax obtained using x-ray can be caused by overexposure. Underexposure might lead to an incorrect diagnosis of interstitial opacification. Panting can lead to motion artifacts, making it difficult to obtain a good-quality x-ray. Patient movement can cause motion artifacts, which makes it more difficult to obtain a good quality x-ray. Increasing the mAs can minimize motion artifacts.
Which of the following is the best technique to consider for an abdominal x-ray?
Peak expiration An abdominal x-ray should be obtained at peak expiration to avoid pressure on the abdominal contents from the diaphragm. Peak inspiration is best used during an x-ray of the thorax. Panting is never ideal during x-rays because of motion artifact.
Which type of magnet consists of two slabs of magnetic material facing each other?
Permanent magnets Permanent magnets consist of two slabs of magnetic material facing each other. Electromagnets, also known as resistive magnets, create an electrical charge applied through copper wire wrapped around a center. Superconducting magnets are electromagnets made of windings that are superconductive.
Which of the following correctly defines the term shims in reference to MRI?
Pieces or plates of metal used to correct the magnetic field within the magnet
What is the difference between color Doppler and power Doppler ultrasound?
Power Doppler is sensitive to slow flow and color Doppler indicates direction of flow
What is the amount used to express the dose equivalent that results from exposure to ionizing radiation known as?
REM
What does the MRI unit use to manipulate hydrogen atoms in and out of an excited energy state?
Radio waves Radio waves are used to manipulate hydrogen atoms in and out of an excited energy state. Helium is used to keep some magnets active. Water does not aid nor hinder the MRI unit. Oxygen does not aid nor hinder the MRI unit.
In dental radiographs, periapical disease appears as a:
Radiolucent area around the apex of the tooth
Atoms that emit particles and energy to become stable are known as:
Radionuclides
Which of the following terms is used to describe the white appearance on an x-ray?
Radiopaque
Which of the following does not describe an old carpal chip seen on x-ray in horses? A - Sharp fragment margination B - Decreased adjacent bone density C - Presence of osteoarthritis D - Normal or cool surrounding tissue
Sharp fragment margination Old carpal chip fractures in horses have all of the following radiographic characteristics: vague fragment margination, decreased adjacent bone density, presence of osteoarthritis, and normal or cool surrounding tissue. Sharp fragment margination is seen with fresh carpal chips in horses.
In MRI what are the various shades of gray referred to as?
Signal intensities
A biarticular fracture is also known as a:
Slab fracture Slab fractures, also known as biarticular fractures, are considered as the most destabilizing and most serious of all carpal fractures
For smaller-sized patients, which radiographic technique is preferred?
Tabletop technique For small-sized patients, a tabletop technique is preferred along with higher mA, shorter exposure time, and lower kVp. The use of a lower mA can result in motion artifact. The use of higher kVp is too much exposure for the small patient.
Exposing a reptile to cool conditions, such as a cool metal surface, will cause what?
Temporary lethargy and immobility Placing a reptile on a cool surface or "chilling" it briefly results in a temporary lethargy or immobility. Excitement, rapid breathing, or aggressiveness can all occur normally when handling reptiles.
When using color-flow Doppler in ultrasound, what do the displayed red and blue colors mean?
The colors show blood flow; blue indicates flow away, and red indicates flow toward
Radiographic projections are named according to which of the following?
The direction in which the central beam anatomically enters the body parts, followed by the area of exit of the x-ray beam
Decreased radiographic density with poor contrast results from which of the following?
The film was underexposed
Which of the following best describes the Nyquist point in ultrasound?
The point at which the maximum blood velocity is reached
Which of the following best describes the term fulcrum?
The point of interest A fulcrum is best described as the point of interest. The fulcrum is typically the central point at which a lever rotates.
What is a major safety concern with MRI machines?
The potential projectile effect with metallic objects within the vicinity of the machine
When obtaining a caudocranial x-ray of the stifle joint, what should be palpated to determine the amount of rotation necessary for an exact caudocranial projection?
The tibial tuberosity
For standard radiographs of the tarsus of a horse, which of the following is the correct weight distribution?
The weight should be evenly distributed on all four legs
For what are grids used on an x-ray machine?
To decrease scatter radiation and to increase the contrast on the radiograph
You are looking at your dental radiograph and notice that the tooth is elongated. This happened because the beam was perpendicular to the:
Tooth
What is a concern of exposure creep with the use of digital x-rays?
Unnecessary patient and personnel exposure because of ionizing radiation
Dental film should be placed in the mouth with the dimple facing:
Up and pointing rostrally
A deformity in which the interior angle of the joint, viewed frontally, is greater than 180 degrees is known as what?
Valgus deformity A valgus deformity is one in which the interior angle of the joint, viewed frontally, is greater than 180 degrees. A varus deformity is one in which the interior angle, viewed frontally, is less than 180 degrees. The term axial rotation pertains to foals with angular limb deformities. The term windswept refers to the combination of valgus and varus deformity.
A deformity, in which the interior angle of the joint, viewed frontally, is <180 degrees, is known as what?
Varus deformity A varus deformity is one in which the interior angle of the joint, viewed frontally, is less than 180 degrees. A valgus deformity is one in which the interior angle, viewed frontally, is greater than 180 degrees. The term axial rotation pertains to foals with angular limb deformities. The term windswept refers to the combination of valgus and varus deformity.
Before taking a radiograph of a patient, what is the proper way to obtain a measurement of the area of interest?
When the patient is in the position in which it is to be x-rayed
The amount of radioisotope used for each examination in a nuclear medicine study is measured in which of the following units?
mCi Radioisotopes used for each examination in a nuclear medicine study are measured in millicurie (mCi) units. X-rays are measured in units of kV and mA. Ultrasound is measured in MHz.
Radiographs of joints must include which of the following?
{1/3} of the bones proximal and distal to the joint
