Patient Care (some mixed)
If extravasation occurs during an IV injection of contrast media, correct treatment includes which of the following? 1. Apply pressure to the vein until bleeding stops. 2. Remove the needle and locate a sturdier vein immediately. 3. Lower arm below heart level.
1
Which of the following voltage ripples is (are) produced by single-phase equipment 1. 100% voltage ripple 2. 13% voltage ripple 3. 3.5% voltage ripple A 1 only B 2 only C 2 and 3 only D 1, 2, and 3
1 With single-phase, full-wave-rectified equipment, the voltage drops to zero every 180° (of the AC waveform); that is, there is 100% voltage ripple. With three-phase equipment, the voltage ripple is significantly smaller. Three-phase, 6-pulse equipment has a 13% voltage ripple, and three-phase, 12-pulse equipment has only a 3.5% ripple. Three-phase, 12-pulse equipment comes closest to constant potential, as the voltage never falls below 96.5% of maximum value.
Which of the following will improve the spatial resolution of image-intensified images? A very thin coating of cesium iodide on the input phosphor A smaller-diameter input screen Increased total brightness gain
1 and 2
Which of the following can have an effect on radiographic contrast? 1. Beam restriction 2. Grids 3. Focal spot size A 1 only B 1 and 2 only C 2 and 3 only D 1, 2, and 3
1 and 2 Radiographic contrast the result of x-ray absorption difference between tissue densities resulting in scale of grays. Since the function of grids is to collect scattered radiation, they serve to shorten the scale of contrast. Beam restrictors function to limit the x-ray field size, thereby reducing the production of scattered radiation and shortening the scale of contrast. Focal spot size is one of the geometric factors affecting spatial resolution; it has no effect on the scale of contrast or receptor exposure. It is the function of radiographic contrast to make details visible.
Which of the following precautions should be observed when radiographing a patient who has sustained a traumatic injury to the hip? When a fracture is suspected, manipulation of the affected extremity should be performed by a physician. The axiolateral projection should be avoided. To evaluate the entire region, the pelvis typically is included in the initial examination. A 1 only B 1 and 3 only C 2 and 3 only D 1, 2, and 3
2 and 3 Typically, traumatic injury to the hip requires a cross-table (axiolateral) lateral projection, as well as an AP projection of the entire pelvis. Both of these are performed using minimal manipulation of the affected extremity, reducing the possibility of further injury. A physician should perform any required manipulation of the traumatized hip.
long scale contrast
A radiograph that demonstrates small differences in density between adjacent areas. Long-scale contrast is a result of high kilovoltage peak (kVp). In dental radiography, for example, 80 to 90 kVp or higher is necessary to produce a radiograph with long-scale contrast.
Although the stated focal-spot size is measured directly under the actual focal spot, focal-spot size in fact varies along the length of the x-ray beam. At which portion of the x-ray beam is the effective focal spot the largest? A At its outer edge B Along the path of the CR C At the cathode end D At the anode end
C
All the following statements regarding CR IPs are true except A IPs have a thin lead foil backing. B IPs can be placed in the Bucky tray. C IPs must exclude all white light. D IPs function to protect the PSP.
C The image plate has a protective function for the flexible photostimulable storage phosphor within; it can be conveniently placed in a Bucky tray or under the anatomic part, and comes in a variety of sizes. The PSP within the IP is the image receptor/detector. IPs do not contain a lightsensitive material and, therefore, do not need to be light-tight. The photostimulable PSP is not affected by light.
All the following rules regarding proper hand washing technique are correct except A keep hands and forearms higher than elbows. B use paper towels to turn water off. C use hand lotions whenever possible. D carefully wash all surfaces and between fingers.
a
What should you do if you discover while taking patient history that the patient scheduled for an intravenous urogram (IVU) takes metformin hydrochloride daily but has no evidence of AKI and with eGFR ≥30 mL/l.732 ? 1. Proceed with the examination if kidney function is normal. 2. Instruct the patient to withhold the metformin for 48 hours after the examination. 3. Reschedule the examination until the patient has been off metformin for 48 hours. A 1 only B 1 and 2 only C 1 and 3 only D 1, 2, and 3
a
In fluoroscopy, the automatic brightness control is used to adjust the A kVp and mA B backup timer C milliamperage (mA) and time D kilovoltage (kV) and time
a As body areas of different thicknesses and densities are scanned with the image intensifier, image brightness and contrast require adjustment. The ABC functions to maintain constant brightness and contrast of the output screen image, correcting for fluctuations in x-ray beam attenuation with adjustments in kilovoltage and/or milliamperage. There are also brightness and contrast controls on the monitor that the radiographer can regulate.
The automatic exposure device that is located immediately under the x-ray table is the A ionization chamber B scintillation camera C photomultiplier D photocathode
a Automatic exposure control (AEC) devices are used to produce consistent and comparable radiographic results. In one type of AEC, there is an ionization chamber just beneath the tabletop above the IR. The part to be examined is centered to it (the sensor) and radiographed. When a predetermined quantity of ionization has occurred (equal to the correct receptor exposure), the exposure terminates automatically. In the other type of AEC, the phototimer/photomultiplier, a small fluorescent screen is positioned beneath the IR. When remnant radiation emerging from the patient exposes and exits the IR, the fluorescent screen emits light. Once a predetermined amount of fluorescent light is "seen" by the photocell sensor, the exposure is terminated. A scintillation camera is used in nuclear medicine. A photocathode is an integral part of the image intensification system
If a radiograph, made using AEC, is overexposed because an exposure shorter than the minimum response time was required, the radiographer generally should A decrease the milliamperage B increase the milliamperage C increase the kilovoltage D decrease the kilovoltage
a Decreasing or increasing the kilovoltage will produce a change in radiographic contrast. The image was overexposed (from excessive exposure time) because the AEC wasn't capable of producing the required extremely short exposure time. To bring the required exposure to an exposure time the AEC is capable of, the mA should be decreased (thus requiring a longer exposure time, within the capability of the AEC).
All of the following are potential digital pre-processing problems, except: A Edge enhancement B Defective pixel C Image lag D Line noise
a Edge enhancement (A) is a type of post-processing image manipulation, which can be effective for enhancing fractures and small, high-contrast tissues. Answers B, C and D are problems that may be encountered in pre-processed digital images
All the following rules regarding proper hand washing technique are correct except A keep hands and forearms higher than elbows. B use paper towels to turn water off. C use hand lotions whenever possible. D carefully wash all surfaces and between fingers.
a Frequent and correct hand hygiene is an essential part of medical asepsis; it is the best method for avoiding the spread of microorganisms. If the faucet cannot be operated with the knee or a foot pedal, it should be opened and (especially) closed using paper towels. Care should be taken to wash all surfaces of the hand and between the fingers thoroughly. The hands and forearms always should be kept higher than the elbows. Hand lotions should be used frequently to keep hands from chapping. Unbroken skin prevents the entry of microorganisms; dry, cracked skin breaks down that defense and permits the entry of microorganisms
Hirschsprung disease, or congenital megacolon, is related to which of the following age groups? A Neonate B Toddler C Adolescent D Adult
a Hirschsprung disease, or congenital megacolon, is caused by the absence of some or all of the bowel ganglion cells—usually in the rectosigmoid area but occasionally more extensively. Hirschsprung disease is the most common cause of lower GI obstruction in neonates and is treated surgically by excision of the affected area followed by reanastomosis with normal, healthy bowel. Hirschsprung disease is diagnosed by barium enema or, in mild cases, by rectal biopsy
A 15% increase in kVp accompanied by a 50% decrease in mAs will result in A decreased patient dose B increase in contrast. C increased brightness. D spatial resolution.
a Since mAs is directly proportional to receptor exposure and patient dose, the receptor exposure is cut in half and patient dose is cut in half. Spatial resolution is unaffected by changes in kVp. Brightness is a function of the computer software.
What lies immediately under the phosphor layer of a PSP storage plate? A Reflective layer B Base C Antistatic layer D Lead foil
a The PSP storage plate within the IP has a layer of europium-activated barium fluorohalide (BaFX: Eu 2 +; X = halogen) mixed with a binder substance. This layer serves as the image receptor when exposed. The barium fluorohalide is usually granular or turbid phosphors. Other examples of turbid phosphors are gadolinium oxysulfide and rubidium chloride. "Needle"-shaped, or columnar phosphors (usually cesium iodide), have the advantage of better x-ray absorption and less light diffusion. Just under the barium fluorohalide layer is a reflective layer that helps direct emitted light up toward the CR reader. Below the reflective layer is the base, behind that is an antistatic layer, and then the lead foil to absorb backscatter. Over the top of the barium fluorohalide is a protective layer.
Which of the following would be useful for an examination of a patient suffering from Parkinson disease? Short exposure time High ratio grid Compensating filtration A 1 only B 1 and 2 only C 1 and 3 only D 1, 2, and 3
a The shortest possible exposure should be used as a matter of routine. Parkinson disease is characterized by uncontrollable tremors, and the resulting unsharpness can destroy image resolution. High ratio grid will absorb a higher percentage of scattered radiation but increase patient dose. Compensating filtration is unrelated to the problem and is not indicated here
To obtain an AP projection of the right ilium, the patient's A left side is elevated 40°. B right side is elevated 40°. C left side is elevated 15°. D right side is elevated 15°.
a When the pelvis is observed in the anatomic position, the ilia are seen to oblique forward, giving the pelvis a "basin-like" appearance. To view the right iliac bone, the radiographer must place it parallel to the IR by elevating the left side about 40° (RPO). The left iliac bone is radiographed in the 40° LPO oblique position.
When comparing the male and female bony pelves, it is noted that the 1. male pelvis is deeper. 2. female pubic arch is greater than 90°. 3. female greater sciatic notch is wider. A 1 only B 1 and 2 only C 2 and 3 only D 1, 2, and 3
all
Which of the following bones participate in the formation of the acetabulum? 1. Ilium 2. Ischium 3. Pubis A 1 and 2 only B 1 and 3 only C 2 and 3 only D 1, 2, and 3
all
Which of the following is (are) essential to high-quality mammographic examinations? Small-focal-spot x-ray tube Short-scale contrast Use of a compression device A 1 only B 1 and 2 only C 1 and 3 only D 1, 2, and 3
all
With which of the following does the femoral head articulate? 1. Ilium 2. Ischium 3. Pubis A 1 only B 1 and 2 only C 2 and 3 only D 1, 2, and 3
all
Which of the following statements regarding dual x-ray absorptiometry is (are) true? It is a low-dose procedure. Two x-ray photon energies are used. Photon attenuation by bone is calculated. A 1 only B 1 and 2 only C 1 and 3 only D 1, 2, and 3
all DXA imaging is used to evaluate bone mineral density (BMD). It is the most widely used method of bone densitometry—it is low-dose, precise, and uncomplicated to use/perform. DXA uses two photon energies—one for soft tissue and one for bone. Since bone is denser and attenuates x-ray photons more readily, their attenuation is calculated to represent the degree of bone density. Bone densitometry/DXA can be used to evaluate bone mineral content of the body or part of it, to diagnosis osteoporosis, or to evaluate the effectiveness of treatments for osteoporosis
Inadequate collimation in CR imaging can result in an image that is too light dark noisy A 1 only B 1 and 2 only C 2 and 3 only D 1, 2, and 3
all It is important to note that histogram appearance as well as patient dose can be affected by the radiographer's knowledge and skill using digital imaging, in addition to his or her degree of accuracy in positioning and centering. Collimation is exceedingly important to avoid histogram analysis errors. Lack of adequate collimation can result in signals outside the anatomical area being included in the exposure data recognition/histogram analysis. This can result in a variety of histogram analysis errors, including excessively light, dark, or noisy images.
Hysterosalpingography may be performed for demonstration of uterine tubal patency mass lesions in the uterine cavity uterine position A 1 and 2 only B 1 and 3 only C 2 and 3 only D 1, 2, and 3
all-d Hysterosalpingography may be performed for demonstration of uterine tubal patency, mass lesions in the uterine cavity, and uterine position. Although hysterosalpingography is often performed to check tubal patency, the uterine anatomy, position, and morphology are also exhibited. In addition, polyps, fibroids, or space-occupying lesions within the uterus are well demonstrated
Patients' rights include which of the following? 1. The right to refuse treatment 2. The right to confidentiality 3. The right to possess his or her radiographs A 1 only B 1 and 2 only C 1 and 3 only D 1, 2, and 3
b
Some patients, such as infants and children, are unable to maintain the necessary radiographic position without assistance. If mechanical restraining devices cannot be used, which of the following should be requested or permitted to hold the patient? A Transporter B Patient's father C Patient's mother D Student radiographer
b
The condition of below-normal blood pressure is termed A hyperthermia. B hypotension. C hypoxia. D bradycardia.
b
The radiographic accessory used to measure the thickness of body parts in order to determine optimum selection of exposure factors is the A gantry. B caliper. C collimator. D ruler.
b
Which of the following bony landmarks is in the same transverse plane as the symphysis pubis? A Ischial tuberosity B Prominence of the greater trochanter C Anterosuperior iliac spine D Anteroinferior iliac spine
b
Verbal disclosure of confidential information that is detrimental to the patient is referred to as A invasion of privacy B slander C libel D assault
b A radiographer who discloses confidential information to unauthorized individuals may be found guilty of invasion of privacy. If the disclosure is in some way detrimental or otherwise harmful to the patient, the radiographer may be accused of defamation. Spoken defamation is slander; written defamation is libel. Assault is to threaten harm; battery is to carry out the threat
During measurement of blood pressure, which of the following occurs as the radiographer controls arterial tension with the sphygmomanometer? A The brachial vein is collapsed. B The brachial artery is temporarily collapsed. C The antecubital vein is monitored. D Oxygen saturation of arterial blood is monitored.
b A stethoscope and a sphygmomanometer are used together to measure blood pressure. The sphygmomanometer's cuff is placed around the midportion of the upper arm. The cuff is inflated to a value higher than the patient's systolic pressure to temporarily collapse the brachial artery. As the inflation is gradually released, the first sound heard is the systolic pressure; the normal range is 110 to 140 mmHg. When no more sound is heard, the diastolic pressure is recorded. The normal diastolic range is 60 to 90 mm Hg. Elevated blood pressure is called hypertension. Hypotension, low blood pressure, is not of concern unless it is caused by injury or disease; in that case, it can result in shock.
Bone densitometry is often performed to measure degree of bone (de)mineralization evaluate results of osteoporosis treatment/therapy evaluate condition of soft tissue adjacent to bone A 1 only B 1 and 2 only C 2 and 3 only D 1, 2, and 3
b Dual x-ray absorptiometry (DXA) imaging is used to evaluate bone mineral density (BMD). Bone densitometry/DXA can be used to evaluate bone mineral content of the body, or part of it, to diagnose osteoporosis, or to evaluate the effectiveness of treatments for osteoporosis. It is the most widely used method of bone densitometry—it is low dose, precise, and uncomplicated to use/perform. DXA uses two photon energies—one for soft tissue and one for bone. Since bone is denser and attenuates x-ray photons more readily, the attenuation is calculated to represent the degree of bone density. Soft tissue attenuation information is not used to measure bone density.
Which of the following groups of analog exposure factors is most likely to produce the longest scale of contrast? A 200 mA, 0.25 second, 70 kVp, 12:1 grid B 500 mA, 0.10 second, 90 kVp, 8:1 grid C 400 mA, 0.125 second, 80 kVp, 12:1 grid D 300 mA, 0.16 second, 70 kVp, 8:1 grid
b Of the given factors, kilovoltage and grid ratio will have a significant effect on the scale of radiographic contrast. The mAs values are almost identical. Because an increased kilovoltage and low-ratio grid combination would allow the greatest amount of scattered radiation to reach the IR, thereby producing more gray tones, B is the best answer. Group D also uses a low-ratio grid, but the kilovoltage is too low to produce as many gray tones as B.
Stochastic effects of radiation include A blood changes B genetic alterations C cataractogenesis D reduced fertility
b Stochastic effects of radiation are nonthreshold and randomly occurring. Examples of stochastic effects include carcinogenesis and genetic effects. The chance of occurrence of stochastic effects is directly related to the radiation dose; that is, as radiation dose increases, there is a greater likelihood of genetic alterations or development of cancer. Deterministic effects are predictable threshold responses; that is, a certain quantity of radiation must be received before the effect will occur, and the greater the dose, the more severe is the effect
The part of a CT imaging system made of thousands of solid-state photodiodes is the A gantry. B detector array. C collimator assembly. D x-ray tube.
b The Correct Answer is: B A CT imaging system has three component parts: a gantry, a computer, and an operating console. The gantry component includes an x-ray tube, a detector array, a high-voltage generator, a collimator assembly, and a patient couch with its motorized mechanism. While the x-ray tube is similar to direct-projection x-ray tubes, it has several special requirements. The CT x-ray tube must have a very high short-exposure rating and must be capable of tolerating several million heat units while still having a small focal spot for optimal resolution. To help tolerate the very high production of heat units, the anode must be capable of high-speed rotation. The x-ray tube produces a pulsed x-ray beam (1-5 ms) using up to about 1000 mA. The scintillation detector array is made of thousands of solid-state photodiodes. These scintillation crystal (cadmium tungstate or rare earth oxide ceramic crystals) photodiode assemblies convert the transmitted x-ray energy into light. That light is then converted into electrical energy and finally into an electronic/digital signal. If the scintillation crystals are packed tightly together so that there is virtually no distance between them, efficiency of x-ray absorption is increased, and patient dose is decreased. Detection efficiency is extremely high—approximately 90 percent. The high-voltage generator provides high-frequency power to the CT x-ray tube, enabling the high-speed anode rotation and the production of high-energy pulsed x-ray photons. Similar to the high-frequency x-ray tubes used in projection radiography, conventional 60-Hz full-wave rectified power is converted to a higher frequency of 500-25,000 Hz. The high-frequency generator is small in size, in addition to producing an almost constant potential waveform. The CT high-frequency generator is often mounted in the gantry's rotating wheel. The collimator assembly has two parts. The prepatient, or predetector, collimator is at the x-ray tube that consists of multiple beam restrictions so that the x-ray beam diverges little. This reduces patient dose and reduces the production of scattered radiation, thereby improving the CT image. The postpatient collimator, or predetector collimator, confines the exit photons before they reach the detector array and determines slice thickness. The patient table, or couch, provides positioning support for the patient. It's motorized movement should be smooth and accurate. Inaccurate indexing can result in missed anatomy and/or double-exposed anatomy
For which of the following examinations can the anode heel effect be an important consideration? Lateral thoracic spine AP femur Right anterior oblique (RAO) sternum A 1 only B 1 and 2 only C 1 and 3 only D 1, 2, and 3
b The heel effect is characterized by a variation in beam intensity that increases gradually from anode to cathode. This can be effectively put to use when performing radiographic examinations of large body parts with uneven tissue density. For example, the AP thoracic spine is thicker caudally than cranially, so the thicker portion is best placed under the cathode. However, in the lateral projection of the thoracic spine, the upper portion is thicker because of superimposed shoulders, and therefore, that portion is best placed under the cathode end of the beam. The femur is also uneven in tissue density, particularly in the AP position, and can benefit from use of the heel effect. However, the sternum and its surrounding anatomy are fairly uniform in thickness and would not benefit from use of the anode heel effect. The anode heel effect is most pronounced when using large IRs at short SIDs and with an anode having a steep (small) target angle.
To maintain image clarity in an image-intensifier system, the path of electron flow from the photocathode to the output phosphor is controlled by A the accelerating anode B electrostatic lenses C the vacuum glass envelope D the input phosphor
b The input phosphor of an image intensifier receives remnant radiation emerging from the patient and converts it to a fluorescent light image. Directly adjacent to the input phosphor is the photocathode, which is made of a photoemissive alloy (usually a cesium and antimony compound). The fluorescent light image strikes the photocathode and is converted to an electron image. The electrons are carefully focused to maintain image resolution by the electrostatic focusing lenses through the accelerating anode and to the output phosphor for conversion back to light.
he risk of inoculation with HIV is considered high for which of the following entry sites? Broken skin Perinatal exposure Accidental needle stick A 1 only B 1 and 2 only C 2 and 3 only D 1, 2, and 3
b The overall chance that a person will become infected with HIV is high with entry sites such as the anus, broken skin, shared needles, infected blood products, and perinatal exposure. Low-risk entry methods include oral and nasal, conjunctiva, and accidental needle stick.
Histogram data that is skewed relative to the values of interest (VOI) of the histogram analysis used for a particular exam may be caused by all of the following, except: A Anatomical structures not centered to the IP B Excessive windowing C The X-ray beam is not correctly aligned to the edges of the IP D The beam edge is irregular because of overlap of a radiopaque shadow, such as a gonadal shield
b Windowing (B) is a post-processing method of adjusting the brightness and contrast in the digital image. Histogram analysis errors occur prior to post-processing of the image. There are two types of windowing: level and width. Window level adjusts the overall image brightness. When the window level is increased, the image becomes darker. When decreased, the image becomes brighter. Window width adjusts the ratio of white to black, thereby changing image contrast. Narrow window width provides higher contrast (short-scale contrast), whereas wide window width will produce an image with less contrast (long-scale contrast). Answers A, C and D can cause histogram data to be skewed relative to the values of interest (VOI) of the histogram analysis used for a particular exam. (S
The male bony pelvis differs from the female bony pelvis in which of the following way(s)? The male pelvis has a larger pelvic inlet. The female pubic arch is greater than 90 degrees. The male ilium is more vertical. A 1 only B 1 and 2 only C 2 and 3 only D 1, 2, and 3
c
A signed consent form is necessary prior to performing all the following procedures except A myelogram. B cardiac catheterization. C upper GI series. D interventional vascular procedure.
c A signed consent form (informed consent) is not necessary prior to performing an upper GI series. Informed consent is necessary before performing any procedure that is considered invasive or that carries considerable risk. A myelogram, a cardiac catheterization, and an interventional vascular procedure are all invasive procedures, and all carry some degree of risk. A physician should explain to the patient what those risks are as well as the risk of not having the procedure. In addition, the patient should be made aware of alternative procedures and the risks associated with the alternatives. Only after the patient has been made aware and all questions have been answered appropriately should the informed consent be signed. A radiographer is not responsible for obtaining informed consent. However, in some institutions, it may be departmental procedure for the radiographer to check the chart and see whether there is a signed consent form in place.
All the following x-ray circuit devices are located between the incoming power supply and the primary coil of the high-voltage transformer except A the timer B the kilovoltage meter C the milliamperage meter D the autotransformer
c All circuit devices located before the primary coil of the high-voltage transformer are said to be on the primary or low-voltage side of the x-ray circuit. The timer, autotransformer, and (prereading) kilovoltage meter are all located in the low-voltage circuit. The milliampere meter, however, is connected at the midpoint of the secondary coil of the high-voltage transformer. When studying a diagram of the x-ray circuit, it will be noted that the milliampere meter is grounded at the midpoint of the secondary coil (where it is at zero potential). Therefore, it may be placed in the control panel safely
Which of the following pathologic conditions would require a decrease in exposure factors? A Congestive heart failure B Pneumonia C Emphysema D Pleural effusion
c Emphysema is abnormal distension of the pulmonary alveoli (or tissue spaces) with air. The presence of abnormal amounts of air makes a decrease from normal exposure factors necessary to avoid excessive receptor exposure. Congestive heart failure, pneumonia, and pleural effusion all involve abnormal amounts of fluid in the chest and, therefore, would require an increase in exposure factors.
Which of the following digital post-processing methods remove high-frequency noise from the image? A Edge enhancement B Windowing C Smoothing D Aliasing
c Image smoothing (C) is a type of spatial frequency filtering performed during digital image post-processing. Also known as low-pass filtering, smoothing can be achieved by averaging each pixel's frequency with surrounding pixel values to remove high-frequency noise. The result is reduction in noise and contrast. Smoothing (low-pass filtering) is useful for viewing small structures such as fine bone tissues. Edge enhancement (A) is a type of post-processing image manipulation, which can be effective for enhancing fractures and small, high-contrast tissues. In digital imaging, after the signal is obtained for each pixel, the signals are averaged to shorten processing time and decrease storage needs. The larger the number of pixels involved in the averaging, the smoother the image appears. The signal strength of one pixel is averaged with the strength of its neighboring pixels. Edge enhancement is achieved when fewer neighboring pixels are included in the signal average. Therefore, the smaller the number of neighboring pixels, the greater the edge enhancement. Windowing (B) is a post-processing method of adjusting the brightness and contrast in the digital image. There are two types of windowing: level and width. Window level adjusts the overall image brightness. When the window level is increased, the image becomes darker. When decreased, the image becomes brighter. Window width adjusts the ratio of white to black, thereby changing image contrast. Narrow window width provides higher contrast (short-scale contrast), whereas wide window width will produce an image with less contrast (long-scale contrast). Aliasing (D) is an image artifact that occurs when the spatial frequency is greater than the Nyquist frequency and the sampling occurs less than twice per cycle. This causes loss of information and a fluctuating signal and wrap-around image is produced, which appears as two superimposed images that are slightly out of alignment, resulting in a moiré effect. The Nyquist theorem states that when sampling a signal (such as the conversion from the analog to digital image), the sampling frequency must be greater than twice the bandwidth of the input signal so that reconstruction of the original image properly displays the anatomy of interest
Quality Control (QC) testing is used to evaluate digital display monitors in all of the following ways, except A Display luminance response B Display resolution C Display matrix size D Display noise
c Monitor display luminance response is evaluated on a regular basis using quality control test patterns such as the TG 18-CT and TG 18-LN test patterns (A). Spatial resolution is the quantitative measure of the ability of the digital display monitor to produce separable images of different points of an object with high fidelity. Test patterns such as the TG 18-CX and TG 18-QC test patterns can be used to evaluate this display resolution (B). Image noise is an important factor in determining the visibility of an object. Any high-frequency variations that interfere with detection of the true signal are classified as noise. Digital display monitor noise can be quantified using the TG 18-AFC test pattern, which is based on the method used to determine noticeable luminance differences in the image (D). The display matrix size is calculated by multiplying the number of pixels in a vertical column by the number of pixels in a horizontal row. The matrix size of the monitor display is fixed. No quality control evaluation is necessary to determine variations in this unchanging characteristic (C).
An exposure was made using 600 mA and 18 ms. If the mA is changed to 400, which of the following exposure times would most closely approximate the original receptor exposure? A 16 ms B 0.16 second C 27 ms D 0.27 second
c Since 18 ms is equal to 0.018 s, and since mA × time = mAs, the original mAs was 10.8. Now it is only necessary to determine what exposure time must be used with 400 mA to provide the same 10.8 mAs (and thus the same receptor exposure) because mA × time = mAs, 400x = 10.8 x = 0.027 second (27 milliseconds)
Which of the following would be appropriate IP front material(s)? 1. Tungsten 2. Magnesium 3. Bakelite A 1 only B 1 and 2 only C 2 and 3 only D 1, 2, and 3
c The IP is used to support the PSP plate. The IP front should be made of a sturdy material with a low atomic number, because attenuation of the remnant beam is undesirable. Bakelite (the forerunner of today's plastics) and magnesium (the lightest structural metal) are commonly used for IP fronts. The high atomic number of tungsten makes it inappropriate as an IP front material.
The total brightness gain of an image intensifier is the product of flux gain minification gain focusing gain A 1 only B 2 only C 1 and 2 only D 1 and 3 only
c The brightness gain of image intensifiers is 5,000 to 20,000. This increase is accounted for in two ways. As the electron image is focused to the output phosphor, it is accelerated by high voltage (about 25 kV). The output phosphor is only a fraction of the size of the input phosphor, and this decrease in image size represents brightness gain, termed minification gain. The ratio of the number of x-ray photons at the input phosphor compared to the number light photons at the output phosphor is termed flux gain. Total brightness gain is equal to the product of minification gain and flux gain.
The device that receives the remnant beam, converts it into light, and then increases the brightness of that light is the A charge-coupled device (CCD) B spot camera C image intensifier D television monitor
c The visual apparatus that is responsible for visual acuity and contrast perception is the cones within the retina. Cones are also used for daylight vision. Therefore, the most desirable condition for fluoroscopic viewing is to have a bright enough image to permit cone (daylight) vision for better perception of anatomic details. The image intensifier accomplishes this. The intensified image is then transferred to a TV monitor for viewing. Spot cameras record fluoroscopic events.
Which of the following is a functional study used to demonstrate the degree of AP motion present in the cervical spine? A Open-mouth projection B Moving-mandible AP C Flexion and extension laterals D Right and left bending AP
c-The degree of anterior and posterior motion occasionally is diminished with a whiplash type of injury. Anterior (forward, flexion) and posterior (backward, extension) motion is evaluated in the lateral position, with the patient assuming the best possible flexion and extension. Left- and right-bending images of the thoracic and lumbar vertebrae are obtained frequently when evaluating scoliosis.
Change in window width affects ___
change in the number of gray shades, that is, image contrast
All the following are part of the Patient's Bill of Rights except the right to A participate in proposed research studies. B continuity of care. C considerate and respectful care. D review any institutional records.
d
Indirect modes of disease transmission include airborne fomite vector A 1 only B 1 and 2 only C 1 and 3 only D 1, 2, and 3
d Airborne, fomite, and vector are all indirect modes of transmitting microorganisms. Direct contact involves actual touching of the infected person. A fomite is an inanimate object that has been in contact with an infectious microorganism (e.g., doorknobs or x-ray tables). Although an inanimate object may serve as a temporary host for microbes, microbes flourish on and in the human host, where plenty of body fluids and tissues nourish and feed them. A vector is an animal host of an infectious organism that transmits the infection via a bite or sting, such as the mosquito or deer tick. Airborne contamination occurs via droplets (sneeze) or dust.
All of the following have an effect on patient dose except A inherent filtration. B added filtration. C SID. D focal spot size.
d Inherent filtration is composed of materials that are a permanent part of the tube housing: the x-ray tube's glass envelope and the oil coolant. Added filtration, usually thin sheets of aluminum, is included to make a total of 2.5 mm Al equivalent for equipment operated at 70 kVp and higher. Filtration is used to decrease patient dose by removing the low-energy photons that do not contribute to image formation but simply contribute to skin dose. According to the inverse square law of radiation, exposure dose increases as distance from the source decreases and vice versa. The effect of focal spot size is principally on spatial resolution; it has no effect on patient dose.
Which of the following combinations would pose the least hazard to a particular anode? A 0.6-mm focal spot, 75 kVp, 30 mAs B 0.6-mm focal spot, 85 kVp, 15 mAs C 1.2-mm focal spot, 75 kVp, 30 mAs D 1.2-mm focal spot, 85 kVp, 15 mAs
d Radiographic rating charts enable the operator to determine the maximum safe milliamperage, exposure time, and peak kilovoltage for a particular exposure using a particular x-ray tube. An exposure that can be made safely with the large focal spot may not be safe for use with the small focal spot of the same x-ray tube. The total number of heat units that an exposure generates also influences the amount of stress (in the form of heat) imparted to the anode. The product of milliampere-second and peak kilovolts determines HU. Groups (A) and (C) produce 2250 HU; groups (B) and (D) produce 1275 HU. Groups (B) and (D) deliver less heat load, but group (D) delivers it to a larger area (actual focal spot), making this the least hazardous group of technical factors. The most hazardous group of technical factors is group (A)
If 92 kV and 15 mAs were used for a particular abdominal exposure with single-phase equipment, what milliampere-seconds value would be required to produce a similar radiograph with three-phase, 12-pulse equipment? A 36 B 24 C 10 D 7.5
d Single-phase radiographic equipment is less efficient than three-phase equipment because it has a 100% voltage ripple. With three-phase equipment, voltage never drops to zero, and x-ray intensity is significantly greater. To produce similar receptor exposure, only two-thirds of the original milliampere-seconds would be used for three-phase, six-pulse equipment. With three-phase, 12-pulse equipment, the original milliampere-seconds would be cut in half (one-half of 15 mAs = 7.5).
A radiograph made with a parallel grid demonstrates decreased receptor exposure on its lateral edges. This is most likely due to A static electrical discharge B the grid being off-centered C improper tube angle D decreased SID
d The lead strips in a parallel grid are parallel to one another and, therefore, are not parallel to the x-ray beam. The more divergent the x-ray beam, the more likely there is to be cutoff/decreased receptor exposure at the lateral edges of the image. This problem becomes more pronounced at short SIDs. If there were a centering or tube angle problem, there would be more likely to be a noticeable receptor exposure loss on one side or the other.
Which of the following vertebral groups form(s) lordotic curve(s)? 1. Cervical 2. Thoracic 3. Lumbar A 1 only B 2 only C 1 and 2 only D 1 and 3 only
d The lordotic curves are secondary curves; that is, they develop sometime after birth. The cervical and lumbar vertebrae form lordotic curves. The thoracic and sacral vertebrae exhibit the primary kyphotic curves, those that are present at birth.
If 300 mA has been selected for a particular exposure, what exposure time would be required to produce 60 mAs? A 1/60 second B 1/30 second C 1/10 second D 1/5 second
d The mAs is the technical factor that regulates receptor exposure. The equation used to determine mAs is mA × s = mAs. Substituting the known factors, 300x = 60 x = 0.2 (1/5) second
The AP axial projection, or "frog leg" position, of the femoral neck places the patient in a supine position with the affected thigh A adducted 25 degrees from the horizontal B abducted 25 degrees from the vertical C adducted 40 degrees from the horizontal D abducted 40 degrees from the vertical
d The patient is supine with the leg abducted (drawn away from the midline) approximately 40 degrees. This 40-degree abduction from the vertical places the long axis of the femoral neck parallel to the IR. Adduction is drawing the extremity closer to the midline of the body
The innominate bone is located in the A middle cranial fossa B posterior cranial fossa C foot D pelvis.
d The two innominate bones (os coxae) make up the pelvis. Each innominate bone is made three bones: ilium, ischium, and pubis. These three bones contribute to form the formation of the acetabulum. When the interior of the acetabulum is viewed, the ilium comprises its upper two-thirds, the ischium comprises its lower posterior two-thirds, and the pubis comprises the lower anterior one-third of the acetabulum.
Geometric unsharpness is most likely to be greater A at long SIDs. B at the anode end of the image. C with small focal spots. D at the cathode end of the image.
d The x-ray tube anode is designed according to the line focus principle, that is, with the focal track beveled (see the figure below). This allows a larger actual focal spot to project a smaller effective focal spot, resulting in improved spatial resolution with less blur. However, because of the target angle, penumbral blur varies along the longitudinal tube axis, being greater at the cathode end of the image and less at the anode end of the image.
Change in window level affects change in ___
image brightness
male pelvis
• Heavy and thick general structure • Greater, or false, pelvis is deep • Pelvis brim, or inlet, is small and heart-shaped • Acetabulum is large and faces laterally • Pubic angle is less than 90° • Ilium is more vertical
female pelvis:
• Light and thin general structure • Greater, or false, pelvis is shallow • Pelvis brim, or inlet, is large and oval • Acetabulum is small and faces anteriorly • Pubic angle is more than 90° • Ilium is more horizontal
