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Using a 48-in. SID, how much OID must be introduced to magnify an object two times?
A. 8-in. OID
B. 12-in. OID
C. 16-in. OID
D. 24-in. OID
24--to magnify object 2x just make it half the sid
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
Factors that contribute to film fog include
1.the age of the film
2.excessive exposure to safelight
The filtering effect of the x-ray tube's glass envelope and its oil coolant are referred to collectively as
Characteristics of low ratio focused grids include the following:
1. they have a greater focal range
2. they are less efficient in collecting SR
3. they can be used inverted
1-2 higher ratio focused grids absorb more SR they have a narrower focal range (focusing distance) and grid/tube centering becomes much more critical.
A lateral lumbar spine using 200 mA, 1-second exposure, and 90 kV. If exposure factors were changed to 200 mA, 0.5 second, and 104 kV, what would change?
2.Scale of radiographic contrast
2.Scale of radiographic contrast
200ma x 1=200 mas
200ma x 0.5 = 100 mas
90-104kvp is 15percent so density is the same, but scale of contrast changes due to higher kvp
The term windowing describes the practice of
A. varying the automatic brightness control B. changing the image contrast and/or density C. varying the FOV D. increasing resolution
changing the image contrast and/or densityC
The term field of view is used to describe
how much of the patient (e.g., 150-mm diameter) is included in the matrix.
When involuntary motion must be considered, the exposure time may be cut in half if the kilovoltage is
A. doubled B. increased by 15% C. increased by 25% D. increased by 35%
increased by 15%---If the exposure time is cut in half, one normally would double the milliamperage to maintain the same milliampere-seconds value and, consequently, the same radiographic density. However, increasing the kilovoltage by 15% has a similar effect
Linear energy transfer (LET) may be best described as
A. the amount of energy delivered per distance traveled in tissue. B. the unit of absorbed dose. C. radiation equivalent man. D. radiation absorbed dose
the amount of energy delivered per distance traveled in tissue
Which technical changes best serve to remedy the effect of very dissimilar tissue densities?
A. Use of high-speed screens B. Use of a high-ratio grid C. High-kilovoltage exposure factors D. High milliampere-seconds exposure factors
High-kilovoltage exposure factors--higher KVP more photons reach film, so more greys
Which is a fast-acting vasodilator used to lower blood pressure and relieve the pain of angina pectoris?
A. Digitalis B. Dilantin C. Nitroglycerin D. Cimetidine (Tagamet)
Angina pectoris is
a spasmodic chest pain that is frequently due to oxygen deficiency in the myocardium.
Film base is currently made of which of the following materials?
A. Cellulose nitrate B. Cellulose acetate C. Polyester D. Glass
Polyester----Cellulose nitrate was used in the past, but it was highly flammable. Cellulose acetate, also used in the past, was not flammable, but it was not as durable as polyester
For radiographic examinations of the skull, it is generally preferred that the skull be examined in the
A. AP projection B. PA projection C. erect position D. supine position
PA projection---(reduce lens dose) low energy photons more likely absorb in the first part they enter, whatever photons that make it to the back of a body part are likely powerful enough to penetrate completely.
Which (are) well demonstrated in the lumbar spine
remember intervertebral foramina are formed by the pedicles
Radiation safety requirements for fluoroscopic equipment include the following:
1. SSD at least 38 cm on stationary (fixed) equipment.
2. SSD at least 30 cm on mobile equipment.
3. high level/boost mode must have continuous audible signal.
all--A cumulative timing device must be available to signal the fluoroscopist (audibly, visibly, or both) when a maximum of 5 minutes of fluoroscopy time has elapsed. High-level mode requires continuous manual activation and audible signal
Which of the following pathologic conditions would require an increase in exposure factors?
A. Pneumoperitoneum B. Obstructed bowel C. Renal colic D. Ascites
Ascites--an abnormal accumulation of fluid in the abdominal cavity
If a patient received 4,500 mrad during a 6-minute fluoroscopic examination, what was the dose rate?
A. 0.75 rad/min B. 2.7 rad/min C. 7.5 rad/min D. 27 rad/hr
A. 0.75 rad/min
4.5 rad divided by 6 =0.75rad per minute
The process of radiation passing through tissue and depositing energy through ionization processes is known as
A. the characteristic effect B. Compton scatter C. linear energy transfer D. the photoelectric effect
C. linear energy transfer
A 5-in. object to be radiographed at a 44-in. SID lies 6 in. from the IR. What will be the image width?
A. 5.1 in. B. 5.7 in.
C. 6.1 in. D. 6.7 in.
B. 5.7 in. (first get OID 44 - 6=38)
SID x object size divided by OID
44 x 5 = 220 divided by 38
Irradiation of macromolecules in vitro can result in
all - Effects on macromolecules include main-chain scission, cross-linking, and point lesions
The uppermost portion of the iliac crest is at approximately the same level as the
A. costal margin B. umbilicus C. xiphoid tip D. fourth lumbar vertebra
D. fourth lumbar vertebra
Which of the following factors impact(s) recorded detail?
all--focal-spot blur---Recorded detail is affected significantly by distance changes because of their effect on magnification.
A radiograph produced using 6 mAs and 110 kVp with an 8:1 ratio grid. repeated using a 16:1 ratio grid. What should be the new mAs?
A. 3 B.6 C.9 D.12
8:1 =4 x mas
16:1 = 6 x mas
so 6 divided by 4 is 1.5
1.5 x 6 = 9mas
The relationship between the intensity of light striking film and intensity of light transmitted through the film is an expression of ?
A. Radiographic contrast B. Radiographic density C. Recorded detail D. Radiographic filtration
Radiographic density --density = incident light / transmitted light
Fluoroscopic imaging of the ileocecal valve is generally part of a(n)
A. esophagram. B. upper GI series. C. small-bowel series. D. ERCP.
Exposures less than the minimum response time of an AEC may be required when
1.using high milliamperage
2.using fast film-screen combinations
3.examining large patients or body parts
( 1-2) If less than the minimum response time is required for a particular exposure, the radiograph will exhibit excessive density. This problem becomes apparent when making exposures that require very short exposure times, such as when using high-milliamperage and fast film-screen combinations
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