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Ch. 13 Physics
Screen-Film Rad Technique
| Question | Answer |
|---|---|
| What are the four exposure factors? | kvp, mA, exposure time, distance(SID) |
| What are the types of filtration? | inherent, added, compensating |
| Kvp controls ______, _________, ________ | contrast, penetrability, image noise |
| What are the types of generators? | single phase, three phase, high frequency |
| How much voltage ripple is on 3 phase 6 pulse generator? | 14 percent |
| How much voltage ripple is on the half wave generator? | 100 percent |
| How much voltage is on the 3phase 12 pulse generator? | 4 percent |
| Radiolucent tissue _________ few x-rays and appears ______. on the radiograph. | attenuates, black |
| Radiopaque tissue _______ x-rays and appears ________ on the radiograph. | absorbs, white |
| What tool is used to measure body part thickness? | Calipers |
| What are the image quality factors? | contrast, optical density, detail, and distortion |
| What controls OD? | mAs and distance |
| to see a change in OD, a change of _____ in mAs needs to be made | 30 percent |
| Detail is the _______ of the radiograph? | sharpness |
| Kvp varies with the thickness of the anatomical part by ____ kVp/cm. | 2 |
| Fixed kvp requires _______ kvp, which has ______ pt dose | high, lower |
| Fixed kvp _____ contrast, ______ latitude | low, wide |
| Variable kvp has fixed ______ and ______ contrast | mAs, higher |
| What are the three pt factors? | pathology, thickness, body composition |
| ____ is the microprocessor technology to program the technique chart into the control unit. | APR |
| The unit of electric current is the _____. | ampere (A) |
| 1 A = ____C/s = _____electrons/s | 1; 6.3x10(18) |
| A double in mA would be a 100% increase or ____ of the x-ray tube current. | doubling |
| mAs does not influence radiation _____. | quality |
| A ____ ____ generator automatically adjust the highest possible mA at the shortest exposure time. | falling-load |
| Time and mA can be used to compensate for each other ______. (p239) | indirectly |
| ____ is one measure of electrostatic charge. | mAs |
| ____ hs no effect on radiation quality. | Distance |
| The large focal spot provide for a shorter exposure time, which minimizes ___ ____. | motion blur |
| More x-rays can be produced with a ___ focal spot. (higher heat capacity) | large |
| ____focal spots are used mainly for fine-detail radiography. | Small |
| The value of inherent filtration is approximately ___ mm Al equivalent. | 0.5 |
| The variable-aperture light localizing collimator provides ___ mm Al equivalent. | 1 |
| __ mm Al filter is inserted between the x-ray tube housing and the collimator. | 1 |
| Total filtration in the x-ray tube is approximately ___ mm Al. | 2.5 |
| What percentage ripple is on a high frequency generator? | <1% |
| Name the four types of body habitus: | sthenic, hyposthenic, hypersthenic and asthenic |
| The chest has ___ subject contrast; the abdomen has ___ subject contrast. | high;low |
| Some pathology is ____, causing the tissue to be more radiolucent. | destructive |
| Some pathology can be ___, causing an increase in mass density and causing the tissue to be more radiopaque. | additive |
| Examples of radiolucent pathology: | atrophy, bowel obstruction, cancer, degenerative arthritis, emphysema, osteoporosis, pneumothorax |
| Examples of radiopaque pathology: | aortic aneurysm, ascites, atelectasis, cirrhosis, pleural effusion, pneumonia, sclerosis |
| The mAs value must be changed by approximately ___% to produce a perceptible change in OD. | 30 |
| An increase in kVp of 15% is equivalent to _____ the mAs. | doubling (15% rule) |
| A 15% increase in kVp accompanied by a half reduction in mAs results in the same ___. | OD |
| kVp is the major factor used in controlling radiographic ____. | contrast |
| High contrast = ____ scale contrast | short (few shades of gray) |
| Low contrast = ____ scale contrast | long (many shades of gray) |
| Grids with ____ ratio increase contrast. | high (grids remove scatter radiation from reaching IR) |
| ___ describes the sharpness of appearance of small structures on the radiograph. | Detail |
| Sharpness of image detail is best measured by ____ _____. | spatial resolution |
| ____ focal spots and ___ SID's will produce the best possible image detail. | Small; increased |
| Visibility of image detail is best measured by ____ _____. | contrast resolution |
| Distortion is controlled by _____ _____. | patient positioning |
| What are the four types of exposure technique charts? | variable kV, fixed kV, high kV and automatic exposure |
| What is the most important factor when talking about AEC? | patient positioning - area of interest must be placed over phototiming device |
| ____ allows the tech to control selection of kVp and mAs by graphics on the control console. | APR (anatomically programmed radiography) |
| The principal advantage of tomography is improved ____ resolution. | contrast |
| The ____ from the object pane an anatomical structure is, the more blurred its image will be. | farther |
| The _____ the tomographic angle, the thinner the tomographic section. | larger |
| Only objects lying in the object ____ are properly imaged. | plane |
| A ____ focal spot must be used for magnification radiography to help reduce the loss of image detail. | small |
| An increase in OID will result in a ____ of scatter that reaches the IR. | decrease (air gap technique) |
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