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MCC Processing
Unit 4 Review
| Question | Answer |
|---|---|
| WHAT IS LUMINESCENCE | EMISSION OF LIGHT FROM A SUBSTANCE BOMBARDED WITH RADIATION |
| WHAT IS FLOURESCENCE | LIGHT EMISSION ONLY WHILE BEING ENERGIZED (DESIRABLE IN INTENSIFYING SCREENS) |
| WHAT IS PHOSPHORESCENCE | AFTER GLOW (GLOWS IN THE DARK)....LIGHT CONTINUES TO EMITTED FOR SOME TIME AFTER RADIATION EXPOSURE HAS ENDED |
| WHAT ARE THE ADVANTAGES OF INTESIFYING SCREENS | TO REDUCE PATIENT DOES, INCREASE CONTRAST OF IMAGES AND INCREASE TUBE LIFE DUE TO LOWER EXPOSURES |
| WHAT ARE THE DISADVANTAGES OF INTENSIFYING SCREENS | REDUCED RESOLUTION (DETAIL SHARPNESS) |
| WHAT IS THE SUBSTRATUM LAYER | THE BONDING LAYER BETWEEN THE BASE AND PHOSPHOR LAYER. IT MAY BE REFLECTIVE, ABSORPTIVE OR TRANSPARENT |
| WHAT ARE THE CHARACTERISTICS OF REFLECTIVE AND ABSORPTIVE | REFLECTIVE INCREASES SPEED AND DECREASES RESOLUTION (OR INCREASES UNSHARPNESS) AND ABSORPTIVE HAVE ADDED COLOR DYE, PREVENTS REFLECTION AND IS FOUND IN SLOWER SCREENS |
| WHICH LAYER IS THE ACTIVE LAYER | PHOSPHOR LAYER |
| PHOSPHOR LAYER | IS A FLOURESCENT LAYER THAT CONTAINS PHOSPHOR CRYSTALS SUSPENDED IN POLYURETHANE. IT INCREASES RESOLUTION BUT DECREASES SPEED |
| WHAT ARE THE RARE EARTH PHOSPHORS | GANDLINIUM OXISULFIDE, LANTHANUM OXISULFIDE, LANTHANUM OXIBROMIDE, YTTRIUM OXISUFIDE AND YTTRIUM TANTALATE. |
| THE THICKER THE PHOSPHOR LAYER......... | THE FASTER THE SPEED, DECREASE IN RESOLUTION (LARGER CRYSTALS) |
| THE THINNER THE LAYER OF PHOSPHOR.......... | THE SLOWER THE SPEED AND SMALLER THE CRYSTALS (HIGHER RESOLUTION) |
| RARE EARTH PHOSPHORS ABSORB HOW MUCH MORE XRAYS THAN CaW04 (CALCIUM TUNGSTATE) | 5 TIMES MORE ABSORPTION |
| CONVERSION EFFICIENCY IS | THE ABILITY TO EMIT MANY LIGHT PHOTONS FOR EVERY XRAY ABSORBED |
| WHAT IS THE CONVERSION EFFICIENCY OF RARE EARTH COMPARED TO CALCIUM TUNGSTATE | 15-20% OR 4-5 TIMES HIGHER |
| CALCIUM TUNGSTATE GLOWS BLUE WHILE RARE EARTHS GLOW | GREEN |
| RARE EARTH INCREASES SPEED WITHOUT......... | COMPROMISING RESOLUTION |
| QUANTUM MOTTLE IS | USING FEW # OF PHOTONS TO MAKE AN IMAGE |
| FEWER PHOTONS (HIGH NOISE) = | GRAINIER THE IMAGE |
| MORE PHOTONS (LOW NOISE) = | SMOOTHER IMAGE |
| WHAT IS THE SPEED OF AN INTENSIFYING SCREEN | THE RELATIVE MEASURE OF THE SCREENS ABILITY TO GIVE OFF LIGHT |
| IF MORE LIGHT MEANS FASTER SPEED AND LESS EXPOSURE THEN LESS LIGHT WOULD MEAN | SLOWER SPEED AND MORE EXPOSURE |
| WHAT IS SPATIAL RESOLUTION/IMAGE BLUR | THE ABILITY TO PRODUCE AN ACCURATE, CLEAR IMAGE OF AN OBJECT'S DETAIL (SHARP IMAGE) |
| HOW IS SPATIAL RESOLUTION MEASURED | IN LINE PAIRS/MM (6-15LP/MM) |
| IF THE CRYSTAL SIZE INCREASES SPEED WHAT HAPPENS TO THE RESOLUTION | IT DECREASES |
| IF THE PHOSPOR LAYER THICKNESS INCREASES THE SPEED WHAT HAPPENS TO THE RESOLUTION | IT DECREASES |
| THE REFLECTIVE LAYER INCREASES THE SPEED AND DOES WHAT TO THE RESOLUTION | DECREASES |
| THE ABSORPTIVE LAYER DECREASES THE SPEED AND THE RESOLUTION | INCREASES |
| CROSSOVER INCREASES THE SPEED BUT __________ THE RESOLUTION | DECREASES |
| WHAT EFFECT DOES QDE HAVE ON SPEED AND RESOLUTION | IT INCREASES THE SPEED BUT HAS NO EFFECT ON RESOLUTION |
| WHAT EFFECT DOES CONVERSION EFFICIENCY HAVE ON SPEED AND RESOLUTION | IT INCREASES THE SPEED BUT HAS NO EFFECT ON RESOLUTION |
| TRUE OR FALSE, SPEED AND RESOLUTION ARE INVERSLY RELATED | TRUE |
| WHAT IS THE FORMULA FOR THE INTENSIFICATION FACTOR | EXPOSURE WITHOUT SCREENS / EXPOSURE WITH SCREENS SO IF 200MAS/5MAS = 40 THEREFORE IT WOULD BE 40 X'S MORE EFFICIENT WITH INTENSIFYING SCREENS |
| WHAT IS THE FORMULA FOR SPEED | SPEED 1 = MAS 2 / SPEED 2 = MAS 1 |
| AS SPEED GOES UP TECHNIQUE GOES | DOWN |
| DIRECT EXPOSURE REQUIRES HOW MUCH MORE RADIATION THAN WITH INTESIFYING SCREENS | 20-50 TIMES MORE RADIATION |
| SPECTRAL COLOR EMISSION OF A SCREEN IS PAIRED WITH......... | THE SPECTRAL SENSIVITY OF THE FILM |
| A MISMATCH OF SCREEN MATCHING RESULTS IN | LOSS OF RESPONSE OF THE FILM OR A LIGHT DENSITY |
| GREEN EMISSION SCREEN IS PAIRED WITH (RARE EARTH) | A GREEN SPECTRAL SENSITIVITY FILM |
| A BLUE EMISSION SCREEN IS PAIRED WITH (CALCIUM TUNGSTATE) | A BLUE SPECTRAL SENSITIVITY FILM |
| WHAT PERCENTAGE OF THE XRAY FILM EXPOSURE IS DUE TO THE LIGHT EMITTED BY THE SCREEN PHOSPHORS | 95-98% |
| THE PRINCIPLE ADVANTAGE OF DIRECT EXPOSURE RADIOGRAPHY COMPARED TO SCREEN RADIOGRAPHY IS | INCREASED RESOLUTION |
| WHEN WOULD YOU USE DIRECT EXPOSURE | FOR SMALL PARTS SUCH AS A FINGER OR HAND |
| THE EMISSION OF LIGHT FROM A PHOSPHOR AFTER INCIDENT RADIATION EXPOSURE IS | PHOSPHORESCENSE |
| THE EFFECT OF QUANTUM MOTTLE IS MOST COMMONLY SEEN WHEN A _________________IS EMPLOYED | FAST FILM SCREEN COMBO |
| RARE EARTH PHOSPHORS ARE A SIGNIFICANT IMPROVEMENT OVER CALCIUM TUNGSTATE SCREEN LARGELY DUE TO THEIR | HIGH CONVERSION EFFICIENCY OR ABSORPTION EFFICIENCY |
| THE PRIMARY ADVANTAGE OF THE USE OF RARE EARTH PHOSPHORS IS | TO REDUCE PATIENT DOSE |
| HOW DO YOU DETERMINE POOR SCREEN CONTACT | BY PERFORMING A WIRE MESH TEST |
| IF A NON SCREEN EXPOSURE REQUIRES 100 MAS AND 75 KEV AND A 100 SPEED SCREEN IS USED AT 5 MAS WITH 75 KEV WHICH GIVES THE SAME RADIATION, WHAT IS TEH INTENSIFYING FACTOR | 100 MAS / 5 MAS = 20 TIMES |
| A RADIOGRAPH IS TAKEN WITH A 50 SPEED SCREEN NON BUCKY USING 40 MAS @ 80 KVP. IF RARE EARTH SCREEN (400) WAS SUBSTITUTED WHAT IS THE NEW MAS | SPEED 1 = MAS 2 / SPEED 2 / MAS 1 THEREFORE 400 / 50 = 8 SO 40 / 8 = 5 MAS |
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misha1228
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