Prime Factors

Question 1

The emission (production) of x-ray photons is controlled by…

Answer 1

1. X-ray tube construction
2. Filtration (get rid of long wavelengths)
3. Tube housing
4. Prime factors

Question 2

Does the RT have control over prime factors?

Answer 2

Yes

Question 3

What are the 4 prime factors that affect the emission of x-rays (in overhead tube)?

Answer 3

1. Kilovoltage (kVp)
2. Milliamperage (mA)
3. Time or seconds (s) - note: mA x s = mAs
4. Distance ([D] = SID)

Question 4

Prime exposure factors are ____ the technologist ___.

The technologist’s job is to know how to ___ these ___ to produce _____.

Answer 4

Prime exposure factors are VARIABLES the technologist CONTROLS.

The technologist’s job is to know how to COMBINE these FACTORS to produce HIGH QUALITY RADIOGRAPHS.

Question 5

What 2 factors affect x-ray emission? What do they measure?

Answer 5

1. Quantitative factors - measurement of the number of x-ray protons in useful beam
2. Qualitive factors - measurement of the penetrating ability of the useful beam

Question 6

Name some quantity factors as well as quality factors

Answer 6

Quantity factors - mA, seconds, kVp, distance, filtration

Quality factors DEPEND ON kVp, filtration

Question 7

Milliamperage

• ___ is the standard abbreviation
• measurement of the _____ or ____ of ___ flowing per ___
• ___ controls the ____ that is applied to the ___
• as ___ increases, so does the number of ___ flowing from the ___ to ___ in X-ray tube

Answer 7

Milliamperage

• mA is the standard abbreviation
• measurement of the TUBE CURRENT or NUMBER of ELECTRONS flowing per SECOND
• mA controls the HEAT that is applied to the FILAMENT WIRE
• as mA increases, so does the number of ELECTRONS flowing from the CATHODE to ANODE in X-ray tube

Question 8

mA and quantity are…

which means…

Answer 8

mA and quantity are DIRECTLY PROPORTIONAL

which means IF THE mA IS DOUBLED, SO IS THE QUANTITY OF TUBE CURRENT OR ELECTRONS

Question 9

What are the common diagnostic ranges of mA stations?

• 200 to 400 mA will…
• 800 to 400 will…

Answer 9

What are the common diagnostic ranges of mA stations? 20 mA - 1200 mA

• 200 to 400 mA will DOUBLE AMOUNT OF TUBE CURRENT OR NUMBER OF ELECTRONS “BOILED” OFF OF THE FILAMENT
• 800 to 400 will CUT THE NUMBER OF ELECTRONS IN HALF

Question 10

Define time/seconds

as exposure time increases…

What will 0.05 to 0.10 do?

What will 0.8 to 0.4 do?

Answer 10

Define time/seconds - LENGTH OF TIME THE HEAT IS APPLIED TO THE FILAMENT WIRE

as exposure time increases, MORE ELECTRONS ARE BOILED OFF THE FILAMENT WIRE

What will 0.05 to 0.10 do? DOUBLES THE ELECTRONS

What will 0.8 to 0.4 do? HALVES THE ELECTRONS

Question 11

Time or seconds of exposure and quantity are…

Answer 11

Time or seconds of exposure and quantity are DIRECTLY PROPORTIONAL TO THE NUMBER OF TUBE CURRENT OR ELECTRONS OR X-RAY PHOTONS

Question 12

Time selections

• short exposure times are…
• older equiptment expresses time in…
• new equiptment expresses time in…

Answer 12

Time selections

• short exposure times are USEFUL IN REDUCING MOTION ARTIFACTS
• older equiptment expresses time in FRACTIONS
• new equiptment expresses time in SECONDS OR MILLISECONDS (ms)

Question 13

Answer 13

Question 14

Answer 14

Question 15

Answer 15

Question 16

mA and seconds are directly ____ to the ____

• if the mA or seconds doubles, so does the ____ or ___ of _____
• if the mA or seconds is cut in half, so does the _____ or ___ of _____

Answer 16

mA and seconds are directly PROPORTIONATE to the TUBE CURRENT

• if the mA or seconds doubles, so does the TUBE CURRENT or NUMBER of ELECTRONS
• if the mA or seconds is cut in half, so does the TUBE CURRENT or NUMBER of ELECTRONS

Question 17

mA x s = mAs

• mAs is the…
• mAs control…
  *

Answer 17

mA x s = mAs

• mAs is the QUANTITY OR NUMBER OF ELECTRONS PER SECOND
• mAs control DENSITY OF THE RADIOGRAPHIC FILM

Question 18

What is density?

Answer 18

The overall blackening or darkening of the film

OR

overall brightness of the image on the monitor

Question 19

What is the formula for mAs, s, and mA?

MUST KNOW FORMULAS!!

Answer 19

• mAs = mA x s (ex, 300 mA x .025 = 75mAs)
• s = mAs/mA (ex, 75 mAs / 300 mA = 0.25 s)
• mA = mAs/s (ex, 50 mAs / 0.10 = 500 mA)

Question 20

30% rule for mAs

• a change of 30% is needed in the mAs value in order to…

50 mAs x .30 = 15 mAs

• If image needs to be ____ : 50 mAs + 15 mAs = 65 mAs
• If image needs to be ____: 50 mAs -15mAs = 35 mAs

Answer 20

30% rule for mAs

• a change of 30% is needed in the mAs value in order to MAKE A NOTICEABLE DIFFERENCE IN THE DARKENING/LIGHTENING OF THE FILM

50 mAs x .30 = 15 mAs

• If image needs to be DARKER : 50 mAs + 15 mAs = 65 mAs
• If image needs to be LIGHTER : 50 mAs -15mAs = 35 mAs

Question 21

Double density

• mA is the majority controlling factor for…
• Doubling the mAs will…
• Halving the mAs will…

Answer 21

Double density

• mA is the majority controlling factor for RADIOGRAPHIC DENSITY
• Doubling the mAs will DOUBLE THE DARKENING OF THE FILM
• Halving the mAs will HALF THE DARKENING OF THE FILM

Question 22

Reciprocity Law - 1875 Bunsen and Roscoe

• studied the relationship of the _______ to the ____
• as long as the mAs value is the same, what doesn’t matter?

Answer 22

Reciprocity Law - 1875 Bunsen and Roscoe

• studied the relationship of the EXPOSURE OF RADIATION to the FILM REACTIONS
• as long as the mAs value is the same, what doesn’t matter? WHAT mA OR TIME STATION IS SELECTED

ex) 25 mA x 2s = 50 mAs

100 mA x 5s = 50 mAs

200 mA x .25 = 50 mAs

Question 23

kVP

1. controls…

• higher kVp will…
• increases…

2. Relationships:

• as kVp increases _____ increases (but not directly proportional)
• as kVp increases, _____ decreases

Answer 23

kVP

1. controls BOTH THE QUANTITY AND QUALITY OF X-RAY BEAM

• higher kVp will INCREASE INTERACTIONS OCCURRING AT THE ANODE TARGET
• increases PENETRATING POWER OF THE BEAM

2. Relationships:

• as kVp increases NUMBER OF PHOTONS increases (but not directly proportional)
• as kVp increases, WAVELENGTH decreases

Question 24

• kVp is known as…
• volts in a unit of…
• kilo is…

so 50 kVp is ____ volts

70 kVP is ____ volts

Answer 24

• kVp is known as KILOVOLTAGE PEAK
• volts in a unit of FORCE OR POWER
• kilo is 1,000

so 50 kVp is 50,000 volts

• 70 kVP is 70,000 volts

Question 25

* Increasing the kVP on the control panel will cause... Remember: volts is the ____ or ___ that cause ____ to move. The higher the \_\_\_\_\_, the higher the _______ in the X-ray tube.

Answer 25

* Increasing the kVP on the control panel will cause **AN INCREASE IN THE SPEED AND ENERGY OF THE ELECTRONS TRAVELING FROM THE CATHODE TO THE ANODE IN THE X-RAY TUBE** Remember: volts is the **ELECTRICAL PRESSURE** or **FORCE** that cause **ELECTRONS** to move. The higher the **VOLTAGE**, the higher the **POTENTIAL DIFFERENCE** in the X-ray tube.

Question 26

What 7 things does kVp control?

Answer 26

1. Potential difference of the x-ray tube 2. Penetration of the x-ray beam 3. Energy of the beam 4. Wavelength of the beam 5. Quality and quantity of the beam 6. Radiation dosage to the patient 7. Speed of electrons

Question 27

kVp is the primary controlling factor of the radiographic ____ or \_\_\_\_ 1. radiographic ___ is the visible differences between ___________ on the radiographic film. The degree of ____ to ___ to ____ shades of the film

Answer 27

kVp is the primary controlling factor of the radiographic **CONTRAST** or **GRAY SCALE** 1. radiographic **CONTRAST** is the visible differences between **2 ADJACENT DENSITIES** on the radiographic film. The degree of **WHITE** to **GRAY** to **BLACK** shades of the film

Question 28

kVp as a controlling factor * kVp should be used to control... * kVp will affect the density on the film but...

Answer 28

kVp as a controlling factor * kVp should be used to control **THE CONTRAST ON THE FILM** * kVp will affect the density on the film but **SHOULD NOT BE USED TO CONTROL THE DARKENING**

Question 29

10% rule of kVp * a change of 10% is needed to... change kVp by 10% = 70 x .1 = 7 70 kVp + 7 kVp = 77 kVp (a little \_\_\_\_) 70 kVp - 7 kVp = 63 kVp (a little \_\_\_)

Answer 29

10% rule of kVp * a change of 10% is needed to **MAKE A NOTICEABLE DIFFERENCE IN THE DENSITY ON A RADIOGRAPHIC FILM** change kVp by 10% = 70 x .1 = 7 70 kVp + 7 kVp = 77 kVp (a little **DARKER**) 70 kVp - 7 kVp = 63 kVp (a little **LIGHTER**)

Question 30

15% rule for kVp * increasing kVp by 15% will... * decreasing kVp by 15% will... 70 kVp x .15 (15%) = 10.5 70 + 10.5 = 80.5 kVp (\_\_\_\_ density) 70 - 10.5 = 59.5 kVp (60) (\_\_\_ density)

Answer 30

15% rule for kVp * increasing kVp by 15% will **DOUBLE THE DENSITY ON THE FILM** * decreasing kVp by 15% will **HALF THE DENSITY ON THE FILM** 70 kVp x .15 (15%) = 10.5 70 + 10.5 = 80.5 kVp (**DOUBLES** density) 70 - 10.5 = 59.5 kVp (60) (**HALF** the density)

Question 31

Distance or SID * SID is... * the ____ of the x-ray beam will vary with the changes in the \_\_\_\_ * increase SID = * decrease SID =

Answer 31

Distance or SID * SID is **SOURCE OF RADIATION TO THE IMAGE RECEPTOR DISTANCE** * the **INTENSITY** of the x-ray beam will vary with the changes in the **DISTANCES** * increase SID = **DECREASE INTENSITY** * decrease SID = **INCREASE INTENSITY**

Question 32

Standard SIDs tabletop or bucky radiography = chest radiography and other selected exams =

Answer 32

Standard SIDs tabletop or bucky radiography = **40" or 100cm** chest radiography and other selected exams = **72" or 180cm**

Question 33

As you increase the distance, the x-ray beam begins to...

Answer 33

As you increase the distance, the x-ray beam begins to **DIVERGE THUS SPREADING OUT THE ENERGY OF RADIATION**

Question 34

What is inverse square law?

Answer 34

Intensity of radiation is inversely related to the square of the distance

Question 35

As SID increases, what decreases? (and vise versa)

Answer 35

As SID increases, beam intensity decreases as beam intensity increases, SID decreases

Question 36

Doubling the distance of the X-ray tube will ______ of the beam by a factor of \_\_\_. 36" SID to 72" SID (radiation will ___ by \_\_)

Answer 36

Doubling the distance of the X-ray tube will **DECREASE THE INTENSITY** of the beam by a factor of **4** 36" SID to 72" SID (radiation will **DECREASE** by **4**)

Question 37

Cutting the distance in half will... 40" SID at 4 mR 20" SID at 16 mR

Answer 37

Cutting the distance in half will **INCREASE THE INTENSITY BY A FACTOR OF 4** 40" SID at 4 mR 20" SID at 16 mR

Question 38

If you took a film at 40" SID and repeated the exam using 60" SID using the same technical factors, what would happen to the density of the radiographic image?

Answer 38

Image would be too light

Question 39

What does the exposures (film density) maintenance formula do?

Answer 39

* Provides technique correction for change in SID * Maintains the same film density

Question 40

Rule of thumb Insensity of the beam and new mAs to maintain density both can...

Answer 40

Rule of thumb Insensity of the beam and new mAs to maintain density both can **RELATE TO FACTORS OF 4**

Question 41

Digital Image Receptor Systems * Density and contrast (controlled through...) * Still, the IR must receive... * What does not allow the production of acceptable image quality?

Answer 41

Digital Image Receptor Systems * Density and contrast (controlled through **POST-PROCESSING)** * Still, the IR must receive **PROPER EXPOSURE** * What does not allow the production of acceptable image quality? **EXTREMELY HIGH OR LOW EXPOSURES**

Question 42

Density = mAs = kVp =

Answer 42

Density = **OVERALL DARKENING OF THE IMAGE** mAs = major controlling factor of density (because controls number of electrons) kVp = controls contrast