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RAD 231 Unit 4 real
| Question | Answer |
|---|---|
| Variations in power distribution to the x-ray machine are corrected by the: | Line voltage compensator |
| A spinning top test has been done using a fully-rectified single-phase generator. Eight dots are shown. What was the exposure time? | 1/15 second |
| Focal spot blooming can be caused by progressive increases in: | mA |
| The disadvantage of the a small target angle is: | less exposure field coverage |
| What is the acceptance criterion for a timer circuit with an exposure time shorter than 10 ms? | 20% |
| The same mAs values achieved with several different mA and time setting must produce the same radiation output within ___% | +/- 10 |
| Which federal agency is responsible for establishing standards for safety and for monitoring the workplace environment? | OSHA |
| Which mode uses 20 to 30 separate frames to produce a single fluoroscopic image? | continuous fluoroscopy mode |
| A transformer with more turns on the secondary side than the primary windings would be expected to: | increase voltage and decrease amperage |
| A focal spot, which is purchased as a 1.0 mm effective focal spot, actually measures 1.39 mm. Is the focal spot acceptable within tolerances permitted by NEMA guidelines? | yes |
| The maximum deviation from the selected kVp, regardless of the mA selected, that should be permitted in keeping with recommended guidelines is: | +/- 5% |
| A quality control program includes: 1. periodic testing of the equipment 2. Acceptance testing 3. Correcting deviance from expected equipment performance/usage | 1, 2 , 3 |
| What is the NEMA allowance parameter for an x-ray tube that has a stated focal spot size of 1.5 mm? | 40% |
| When checking lead aprons and gloves for cracks and tears the fluoroscopic check will confirm such problems, characteristically by _____________. | bright light areas |
| The test that is NOT conducted as part of AEC quality control is: | light field-radiation field congruence |
| Old radiographic equipment (greater than 8 years) that has high volume should have quality control testing performed: | semiannually |
| A synchronous spinning top has been used to check the exposure timer of an x-ray generator. An arc of 18 degrees is demonstrated on the finished image. What was the time of the exposure? | 1/20 sec. |
| Exposure time directly affects the total quality of radiation emitted from an x-ray tube; therefore, an accurate exposure timer is critical for properly exposed images and reasonable patient radiation exposure. | False |
| What is the accepted half-value layer (HVL) for an x-ray unit operating at 80 kVp? | 2.3 mm Al |
| When checking the linearity of the generator, the maximum variability allowed is: | 10% |
| Because of the line focus principal, the effective focal spot decreases with decreasing: | target angle |
| An x-ray tube operates most efficiently to produce x-rays when supplied by: | High voltage DC |
| Focal spots less than 0.8mm have a variance up to ______ greater than the stated size. | 50% |
| Milliamperage in the x-ray tube is determined by the: | Heat of the filament |
| When performing the timer accuracy test, if 30 dots are counted for a single-phase, full-wave rectified unit, then the actual exposure time is: | 1/4 sec. |
| Which term describes the parameter that measures illuminance in the area where the primary reading will take place? | ambient light |
| Grids should be periodically evaluated for: | uniformity |
| Which government agency mandates a policy on exposure to blood-borne pathogens? | OSHA |
| The maximum variation for reproducibility of exposure is: | 5% |
| X-ray system mAs reciprocity has an acceptance parameter of: | +/- 10% |
| The ______can be used to measure digital imaging display monitor quality. | SMPTE pattern |
| As an x-ray tube ages, the inside can become coated with tunsgten, which can cause __________ in the tube. | arcing |
| Which of the following tests can be used to determine focal spot size? | star pattern test |
| A step-down transformer is located in the ____________________ circuit. | Filament |
| What was enacted in order to increase the amount of information the FDA and device manufactors receive about problems with medical devices? | SMDA (Safe Medical Devices Act) |
| During AEC evaluation with varying kVp, the AEC system should maintain receptor exposure not to exceed __________ difference in pixel brightness. | 50% |
| Which of the following does not improve the heat capacity of the tube? | an increased target angle |
| The ____ measures the size of the focal spot. | slit/star test pattern |
| To achieve a long exposure time with an electronic timer, the amount of resistance in the timer circuit must be: | high |
| The light field and radiation field of an imaging unit must be congruent to within ____ of the SID. | +/- 2% |
| An unwanted component on a radiographic image is called: | artifact |
| Almost all digital images in medical imaging are viewed and interpreted on a __________________. | digital display device |
| The sum of the differences between the light and the x-ray field edges for systems with PBL must be within ___of the SID. | 2% |
| The x-ray beam must be mounted inside its housing so that the central ray exits the housing to within ____ degree(s) of perpendicular. | 1 degree |
| Which of the following devices can be used as the sensor in AEC units? a. Solid-state detector b. Photodetector c. Ion chambersed as the sensor in AEC units? d. All of the above | All of the above |
| The input phosphor of an image intensifier tube converts a(n) ________ image into a(n) ______ image. | x-ray: light |
| The minimum total filtration required for general purpose imaging systems is: | 2.5 mm Al |
| Which digital image artifact is caused when detector elements in the active matrix array stop working? | dropped pixels |
| The measurement of the level of quality at some point in time with no effort to change or improve the level of care is known as quality: | assessment |
| A grid that is out of alignment is most likely to: | remove a measurable amount of primary radiation |
| If the x-ray field is smaller than that indicated by the indicator knob on the collimator, a technologist risks: | clipping anatomy |
| The penetrability or filtration of an x-ray beam is reported in terms of its: | HVL |
| What is the most common cause of tube failure? | tungsten vaporization |
| Which of the following artifacts is mostly likely to result if a computed radiography imaging plate was incompletely erased? | phantom or ghost images |
| A transformer with 300 turns on the primary side, input side and 40, 000 turns on the secondary side is the _____transformer. | step-up |
| Fluctuations of kilovoltage affect the penetrating capabilities of the beam, as well as the image contrast, receptor exposure and patient dose. | True |
| The nine penny test evaluates ______________. | Light-field-Radiation field Alignment |
| Two common quality control tests that should be performed on grids are grid _________ and grid _______ tests. | alignment; uniformity |
| Which of the following should a quality control program for radiographic equipment include: 1. Visual inspection 2. Environment inspection 3. Performance testing | 1, 2, 3 |
| During the exposure linearity test, the mR/mAs should vary no more thant + or - % from the average. | 10 |
| A digital display monitor is best viewed ______________. | at least 80 degrees angle |
| When using the synchronous timer the length of the arc is divided by ________ degrees because one slit travels that many degrees in _________. | 360; one sec. |
| The goal of the filament circuit is to: | Heat the filament wire located in the cathode |
Created by:
Btran573