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The three controlling factors of radiographic contrast are what?
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MRO module 3
| Question | Answer |
|---|---|
| Subject contrast | The contrast that results from differences in tissue density in the patient |
| The three controlling factors of radiographic contrast are what? | 1)kVp 2)Subject contrast 3)Image receptor |
| Potential difference | Aka electric potential; potential energy per unit charge |
| Kinetic energy | The energy of an object in motion |
| Penetrometer | Step wedge; a device for measuring the penetrability of x-rays |
| What are the four general tissue groups? | Fat, Muscle, Water, Bone (subject contrast) |
| Photoelectric effect | The process that occurs when an incident x-ray photon is absorbed by the atom it strikes and an electron is ejected from the inner shell of that atom |
| Which of the four general tissue groups has the highest effective atomic number? Bone, Fat, Muscle, or Water? | Bone has the highest effective atomic number of the tissue groups |
| What is the primary x-ray absorber in bone? | Calcium |
| Muscle can vary greatly in the way it affects the x-ray beam. This due to: 1)Hydration level 2)Tissue thickness 3)Age? | All |
| The lower the kVp, the higher the resultant contrast. | |
| The following are calculated differences between adjacent densities. Which of the following represents low contrast? 1)1.8 2)1.5 3)1.0 4)0.5 | 4) 0.5 |
| The following are x-ray photon energies. Which one is more likely to contribute to the darkest shades of an image? 1)20KeV 2)30KeV 3)50KeV 4)100KeV | 4)100 KeV. (The greater the photon energy, the more penetration that occurs in the tissue and the darker that area in the image will be) |
| kVp is the primary controlling factor in determining contrast because it: | Determines the penetrating power |
| The way x-rays interact with bone will vary with: | Age, Pathology, and Health |
| Film contrast | The inherent ability of a radiographic film to record a range of densities |
| Emulsion | The layer in the film that contains the silver halide crystals suspended in gelatin |
| What are the five layers in intensifying screen? | 1)Backing (base) 2)Reflective layer 3)Active layer (phosphor layer) 4)Abrasion layer (protective layer) 5)Edge seal |
| Layers of film are? | 1)Base 2)Adhesive layer 3)Emulsion layer 4)Protective layer. (Remember that the base is in the center and these layers will be on both sides of the base) |
| Base | a layer of polyester with a blue dye added to reduce eye strain. It provides the foundation for the emulsion layers and the film itself. |
| Adhesive layer | layers of adhesive (one on each side of the base) to bond the base to the emulsion |
| Emulsion layer | The emulsion is the heart of the film and is made of silver halide crystals and a suspension medium |
| Protective layer | supercoat or overcoat layers that protect the emulsion from damage. These are the layers that are physically touched when film is handled. |
| Sensitivity specks | Impurities in the film emulsion that attract silver ions produced when x-rays interact with the silver halide crystals; these clumps of silver ions are converted into black metallic silver by the development process |
| Reducing agents | A substance capable of donating electrons to another substance, thereby reducing the second substance and itself becoming oxidized. |
| With intensifying screens the emission of many light photons per x-ray interaction is called what? | Conversion efficiency |
| Where does black metallic formation begin? | Sensitivity speck |
| In general purpose x-ray film, which layer is not duplicated? | Base |
| Which layer of the film is manufactured to help reduce eye strain? | The base |
| Scatter decreases contrast | |
| Grids increase contrast | |
| Development fog | A generalized graying of a radiograph that results when unexposed silver crystals in the film are developed |
| Compensating filtration will decrease contrast. T or F? | True |
| An increase in developer time will have what effect on contrast? | Decreases it |
| Increasing OID can have an effect on radiographic contrast similar to a grid. T or F? | True |
| Collimation has what effect on image contrast? | Increases it |
| A grid will decrease scatter production. T or F? | False |
| Scatter radiation has what effect on scale of contrast? | Decreases it |
| Which tissue group will likely have the greatest number of compton effects? | Muscle |
| Which tissue group has the lower water content? | Fat |
| Which tissue group has the highest water content? | Muscle |
| X-ray energy is converted to light in which layer of the intensifying screen? | Active layer |
| Which layer of the film contains the silver halide crystals? | Emulsion |
| Once the silver halide crystals are exposed, the sensitivity speck will first acquire what charge? | Negative |
| Why is scatter exposure undesirable? | Decreases contrast |
| What is the x-ray absorbing material in grids? | Lead |
| Collimation acts to reduce scatter and its resultant image fog primarily by what? | Limiting area of exposure |
| Compensating filters in effect increase tissue thickness and density. T or F? | True |
| Which OID would result in the greatest increase in radiographic contrast? 1 inches, 4 inches, 6 inches, 12 inches? | 12 inches |
| A positive contrast media will have what effect on radiographic contrast? | Increase |
Created by:
volcomgrl12