Instructions for Side by Side Printing
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Chapter 11,12 & 13 Radiographic Imaging
front 1 1. 15 percent rule | back 1 The 15 percent rule states that an increase in kVp by 15 percent will cause a doubling in exposure, the same effect as doubling the mA or doubling exposure time. |
front 2 2. Direct Square Law | back 2 Exposure maintenance formula |
front 3 3. Exposure maintenance formula | back 3 A direct square law; mAs must increase when distance increases, and vice versa, in order to maintain image receptor exposure. |
front 4 4. milliamperage- second mAS | back 4 The unit used to describe the product of tube current and exposure time. |
front 5 5. Penetrability | back 5 The ability of the x-ray to pass through structures and tissues. |
front 6 6. Prime factor | back 6 Factors related to x-ray emission that are under the direct control of the radiographer; milliamperage, kilovoltage, and distance. |
front 7 7. Reciprocity Law | back 7 The dentistry on an x-ray film should remain unchanged as long as the intensity and duration of the x-ray exposure remains unchanged. |
front 8 8. x-ray quality | back 8 The penetrating ability of the x-ray beam. Kilovoltage and filtration are the main factors. |
front 9 9. x-ray quantity | back 9 The measure of the number of photons in the useful beam. Measured in R (roentgen). Milliamperage-second, kilovoltage, Distance and filtration are the main factors. |
front 10 10. The principle controlling factors for quantity is | back 10 mAs |
front 11 11. The principle controlling factor for quality is | back 11 kVp |
front 12 12. mAs is | back 12 A measure of the tube current and is equal to the number of electrons crossing from cathode to anode. Exposure time is also directly proportional to the number of electrons crossing the tube. |
front 13 13. mAs is calculated by | back 13 mA X time |
front 14 14. What does mAs stand for | back 14 milliamperage per second |
front 15 15. what is the formula for mAs | back 15 mA X time |
front 16 16. What is mAs the measure of | back 16 tube current |
front 17 17. What happens as mAs is increased | back 17 density increases |
front 18 18. as mAs doubles the exposure does what | back 18 doubles |
front 19 19. what happens to the filament of the circuit as mA is increased | back 19 thermionic emission |
front 20 20. Density is the | back 20 the amount of blackening on the image that is determined by exposure. mAs is the primary controller. |
front 21 21. What is D-max | back 21 The maximum density a film can achieve (Film only) |
front 22 22. Reciprocity law | back 22 the density on an x-ray film should remain unchanged as long as the intensity and duration of the exposure remains unchanged. |
front 23 23.When does the reciprocity law fail | back 23 The law fails at very short times (below 10 milliseconds) and very long times (6-7 seconds) |
front 24 24. Low kVp gives an image what type of contrast | back 24 high contrast |
front 25 25. An increase in kVp by 15% will do what to the exposure | back 25 double the exposure |
front 26 26. A decrease in kVp by 15% will do what to the exposure | back 26 cut the exposure by 1/2 |
front 27 27. x-ray intensity does what as distance from the tube decreases | back 27 increases |
front 28 28. x-ray intensity will do what as the distance from the tube increases | back 28 decrease |
front 29 29. Inverse square law | back 29 the intensity of the radiation at a given distance from the point of the source is inversely proportional to the square of the distance. |
front 30 30. A radiographer makes an exposure using the standard 40 inch SID . An ionization chamber measures the radiation at 40 inch SID to be 5 R. The same exposure is made at 45 inch SID what is the new intensity. | back 30 5R/I 2= 452/402 I2=3.9 the new intensity is 3.9R |
front 31 31. Density maintenance formula | back 31 mAs1/mAs2 = D1 2/D2 2 |
front 32 32. The density maintenance formula demonstrates what? | back 32 a relationship where mAs needed for an exposure is directly proportional to the square of the SID and as SID increases the mAs must also increase to maintain adequate blackening on the film. |
front 33 33. A radiographer exposes a patient's chest at the bedside using 3 mAs, 75 kVp at 72 SID. A second radiograph is needed but as a result of a change in the patient's condition, only 54 inch SID can be used what should the new mAs be for the 54 inch SID? | back 33 3mAs/x mAs = 722/ 542 2916(3)/x = 5184 x= 1.69 mAs |
front 34 34. What are three prime factors that affect x-ray emission | back 34 mAs, kVp, Distance |
front 35 35. What is the unit of measurement for x-ray quantity? | back 35 roentgen (R) |
front 36 36. Define ampere? | back 36 The unit of current |
front 37 37.What is the relationship between mAs and density/IR exposure? | back 37 The densities are a direct result of an x-ray exposure to the film and intensifying screens (IR) |
front 38 38. What effects does increased kVp have on the speed and energy of the electrons in the x-ray tube? | back 38 Increase kVp will cause an increase in the speed and energy of the electrons applied across the x-ray tube. |
front 39 39. What is the relationship between kVp and density/IR exposure | back 39 Increase kVp causes an increase in penetrability, which will result in an image with less contrast. the effect of kVp on density/IR exposure will be detailed. |
front 40 40. Annihilation reaction | back 40 Matter being converted back into energy as a result of a position combing with a negative electron, which creates two photons moving in opposite directions |
front 41 41. Attenuation | back 41 The reduction in the number of x-ray photons in the beam, and subsequent loss of energy, as the beam passes through matter. |
front 42 42. Backscatter radiation | back 42 Photons that deflect back towards the source, traveling in the opposite direction of the incident photon. |
front 43 43. Characteristic cascade | back 43 The reaction of electrons dropping into the holes created during a characteristic interaction until there is only a hole in the outer shell. |
front 44 44. Characteristic photon | back 44 An x-ray photon created by the electron transfer from one shell to another. |
front 45 45. Coherent scatter | back 45 An interaction between x-rays and matter characterized by interaction between a very-low-energy x-ray photon and matter causing the electron to vibrate at the same frequency as the incident photon, which then produces a secondary photon but travels in a different direction. |
front 46 46. Compton effect also called Compton scattering | back 46 An interaction between x-rays and matter characterized by an incident x-ray photon interacting with a loosely bound outer-shell electron, resulting in removal of the electron from the shell, which then proceeds in a different direction as a scattered photon. |
front 47 47. Compton (or recoil) electron | back 47 The dislodged electron resulting from compton scattering |
front 48 48. Compton scattered photon | back 48 The photon the exits the atom in a different direction as a result of compton scattering. |
front 49 49. Negatron | back 49 A negatively charged electron resulting from pair production |
front 50 50. Pair production | back 50 An interaction between x-rays and matter characterized by the conversation of the energy of an x-ray photon into matter in the form of two electrons. |
front 51 51. Photodisintegration | back 51 An interaction between x-rays and matter characterized by the interaction between a high-energy photon and the nucleus. The high energy photon strikes the nucleus; the nucleus absorbs all the photon's energy and then emits a nuclear fragment. |
front 52 52. photoelectric absorption | back 52 An interaction between x-rays and matter characterized by an incident electron with slightly greater energy than the binding energy of the electrons in the inner shells, ejecting an electron from the inner shell while being absorbed in the reaction, resulting in an ionized atom. |
front 53 53. photoelectron | back 53 An ionized atom with a missing inner-shell electron resulting from ejection of the electron due to photoelectric absorption. |
front 54 54. Positron | back 54 A positively charged electron resulting from pair production. |
front 55 55. Radiation fog | back 55 The result of scattered photons striking the radiographic film and placing a density on the film that is unrelated to the patient's anatomy. |
front 56 56. Scattering | back 56 The interactions of x-ray photons and matter that cause a change in direction of the photons |
front 57 57. Secondary radiation | back 57 A characteristic photon created by occurring outside the x-ray target. |
front 58 58. Five Basic interactions between x-rays and matter | back 58 1. photoelectric absorption 2. Coherent Scattering 3. Compton Scattering 4. Pair production 5. Photodisintegration |
front 59 59. Rule one that governs the possibility of a photoelectric interaction | back 59 The incident x-ray photon energy must be greater than the binding energy of the inner-shell electron. |
front 60 60. Rule two that governs the possibility of a photoelectric interaction | back 60 A photoelectric interaction is more likely to occur when the x-ray photon energy and the electron binding energy are nearer to one another. |
front 61 61. Rule three that governs the possibility of a photoelectric interaction. | back 61 A photoelectric interaction is more likely to occur with an electron that is more tightly bound in its orbit. |
front 62 62. What happens to the atom after photoelectric absorption | back 62 the atom becomes ionized |
front 63  63. What type of interaction is this? | back 63 Compton scatter interaction |
front 64  64. What type of interaction in this? | back 64 Coherent scatter interaction |
front 65  65. What type of interaction in this? | back 65 Photoelectric interaction |
front 66  66. What type of interaction in this? | back 66 Pair Production |
front 67  67. What type of interaction in this? | back 67 Photodisintegration interaction |
front 68 68. Subject Density | back 68 Will be altered by changes in the amount or type of tissue being irradiated |
front 69 69. Subject Contrast | back 69 Degree of differential absorption resulting from the differing absorption characteristics of the tissues in the body |
front 70 70. Subject Detail | back 70 Dependent on the position of structures within the body and the body's placement in relationship to the film. One primary factor that affects this is distance. |
front 71 71. Subject distortion | back 71 Characterized by the position of the patient. If the patient is not positioned specifically to demonstrate a particular structure this is misrepresentation of size or shape may occur. |