rt 123 wk 3 lecture #3
DESCRIPTION
RT 123 WK 3 Lecture #3. PRINCIPLES OF TECHNIQUE AND EXPOSURE. Factors Affecting DETAIL. MAGNIFICATION DISTORTION TECHNIQUE SELECTION (TIME) FOCAL SPOT SIZE IR Speed (f/s) OID / SOD / SID Factors Affecting DENSITY PATIENT THICKNESS,PATHOLOGY MAS & KVP SID. OID. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/1.jpg)
1 RT 123
WK 3Lecture
#3
PRINCIPLES OF TECHNIQUE AND EXPOSURE
![Page 2: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/2.jpg)
2Factors Affecting DETAILMAGNIFICATIONDISTORTIONTECHNIQUE SELECTION (TIME)FOCAL SPOT SIZEIR Speed (f/s) OID / SOD / SIDFactors Affecting DENSITYPATIENT THICKNESS,PATHOLOGYMAS & KVPSID
![Page 3: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/3.jpg)
3
![Page 4: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/4.jpg)
4
![Page 5: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/5.jpg)
5
![Page 6: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/6.jpg)
6
OID
![Page 7: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/7.jpg)
7
Part to IR position
![Page 8: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/8.jpg)
8
Detail
![Page 9: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/9.jpg)
9
OID
![Page 10: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/10.jpg)
10
Part to IR position
![Page 11: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/11.jpg)
PRIME FACTORSSID BEFORE YOU LEAVE THE ROOMKVP CONTAST RANGE FOR PARTMAS CHANGES WITH PT SIZE , Pathology
11TECH NICAL FACTORSAFFECTING QUALITY
![Page 12: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/12.jpg)
Producing optimal radiographs
12
![Page 13: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/13.jpg)
SID & SOD
SID –Source to Image Receptor Distance TUBE TO CASSETTE 40” (44) AND 72 “ STANDARD
SOD - Source to Object Distance NOT LESS THAN 12 “ SHOULD BE 15”
13
![Page 14: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/14.jpg)
SID CHEST 72 “ = 6’ (WING SPAN)
NOT 10’ (120”)
TUBE LOAD – Heat load on tube – the longer the SID the more Technique required to produce the image
14
![Page 15: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/15.jpg)
IMAGES DENISITY = THE AMOUNT OF BLACKENING
“DARKNESS” ON THE RADIOGRAPH
CONTRAST – THE DIFFERENCES BETWEEN THE BLACKS TO THE WHITES
15
![Page 16: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/16.jpg)
TECHNICAL FACTORS KVP / MAS / SID DEPENDING ON PART & SIZE of PART
Use FASTEST TIME POSSIBLE – TO REDUCE MOTION ↑ kVp & ↓ Mas = lower Patient dose
16
![Page 17: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/17.jpg)
17
How does the techniqueInfluence the imageFilm screen / CR / DR ?????
CONTRAST & DENSITYPRIME FACTORS
![Page 18: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/18.jpg)
18
Radiographic Prime factors The factors principally responsible for x-ray quality and
quantity. These are mAs, kVp, distance (SID).
![Page 19: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/19.jpg)
19X-ray quantity (mAs)is a measure of the number of x-ray photons in the beam. Also called x-ray output, intensity or exposure.
X-ray quality (kVp)is a measure of the penetrating ability of the x-ray beam
![Page 20: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/20.jpg)
20
IMAGES DENISITY = THE AMOUNT OF BLACKENING
“DARKNESS” ON THE RADIOGRAPH
CONTRAST – THE DIFFERENCES BETWEEN THE BLACKS TO THE WHITES
![Page 21: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/21.jpg)
21
Digital Imaging AMOUNT OF ‘BRIGHTNESS” Can be controlled and changed with computer**** *** proper technique and exposure index still important
OverexposedReferring to a radiograph that is too dark because tooUnderexposedReferring to a radiograph that is too light because too x-radiation reached the image receptor
Film Screen
![Page 22: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/22.jpg)
22
Good techniques – importantfor GOOD images + lower PT doses
![Page 23: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/23.jpg)
23
EXPOSURE FACTORS STILL IMPORTANT!
![Page 24: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/24.jpg)
24
![Page 25: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/25.jpg)
25
![Page 26: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/26.jpg)
26
![Page 27: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/27.jpg)
27
80 Ma x.04s vs 160 ma X .02 ?mas
3.2
![Page 28: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/28.jpg)
28
MAS DOUBLED – DENSITY
![Page 29: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/29.jpg)
29
Kvp & contrast (F/S)
![Page 30: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/30.jpg)
30
“SHORT” VS “LONG” SCALE low kVp Higher kVp
More on this in Ch 11, 25 & 26 Next week !
![Page 31: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/31.jpg)
31
![Page 32: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/32.jpg)
32
![Page 33: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/33.jpg)
33
How Are X-rays Made?X-rays are produced
when electrons strike a metal target.
The electrons are liberated from the heated filament and accelerated by a high voltage towards the metal target.
The X-rays are produced when the electrons collide with the atoms and nuclei of the metal target.
mAs – amount
kVp - energy
![Page 34: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/34.jpg)
Kilovoltage Peak - kVp
One kilovolt is = to 1000 volts The amount of voltage selected
for the x-ray tube Range 45 to 120 kVp
(diagnostic range) kVp controls contrast
mA X s = mAs
34MilliamperagemAs
•One milliampere is equal to one thousandth of an ampere.•The amount of current supplied to the x-ray tube•Range 10 to 1200 mA
![Page 35: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/35.jpg)
35
Time In seconds How long x-rays will be produced 0.001 to 6 seconds
![Page 36: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/36.jpg)
36
MAS Changes -at least 20 - 30 % mas change needed to see a visible change in density
![Page 37: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/37.jpg)
37
![Page 38: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/38.jpg)
38
+ 25% + 50 % mas
![Page 39: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/39.jpg)
39
+ 15% kvp = 15% kvp
![Page 40: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/40.jpg)
40
Influencing factors: kVp 15% rule:
15% kVp = doubling of exposure to the film 15% kVp = halving of exposure to the film
15% rule will always change the contrast of the image because kV is the primary method of changing image contrast.
Remember : 15% change ( ) KVP has the same effect as
doubling or ½ the MAS on density
![Page 41: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/41.jpg)
41
CHEST RADIOGRAPHY UPRIGHT - WITH GRID
KVP RANGE (90 – 120 )
MAS ( 1 – 3 PA) ( 5 – 20 LAT)
![Page 42: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/42.jpg)
42
“AVE” CHEST EXPOSURE - 2 IMAGES (Ave – Pt meas 23cm pa 40cm lat)
PA 110 KVP 5 MAS 16:1 GRID 400RS 72”LAT 110 KVP 20 MAS 16:1 GRID 400 RS 72”
![Page 43: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/43.jpg)
43
FOR CHEST – TO GO FROM PA TO LAT:
↑ Technique by 4 x = Double the MAS and go up 10 kvp
INCREASE DENSITY BY 4 X you could: Example: PA CHEST: 2 mas - 110 kvp
FOR LATERAL:
Go up 4 X in mas 8 mas - 110 kvp
Go up 2 X MAS & ↑ 15% Kvp 4 mas - 125 kvp
![Page 44: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/44.jpg)
44
MAINTAIN SAME ODFOR CHEST FILM
80 KVP , 5 MAS, 94 ?
![Page 45: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/45.jpg)
45
CHEST RADIOGRAPH: too light& want longer scale contrast
4 mAs 85 KVP ____ mAs ____ KVP
![Page 46: RT 123 WK 3 Lecture #3](https://reader035.vdocuments.mx/reader035/viewer/2022062520/56815e0c550346895dcc66f9/html5/thumbnails/46.jpg)
46
Shorten TIME 400 MA, 1/20s, 70 KVP 100 MA, _____ , 80 KVP