Exposure and Effects Word Scramble
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Question | Answer |
Dose limit for radiologic personnel | 5 rem/yr |
Rem = ?Rad = ?Roentgen | Rad = Rem = Roentgen for x-ray radiation |
3 ways to estimate patient dose | 1. Entrance skin exposure 2. Gonadal dose 3. Mean marrow dose |
Cardinal Principles of Radiation Protection | 1. Minimize time 2. Maximize distance 3. Maximize shielding |
High level radiation exposure leading to death within days or weeks | Acute Radiation Syndrome |
4 Period of Acute Radiation Syndrome | 1. Prodromal 2. Latent 3. Manifest 4. Recovery or Death |
decreased WBCs, decreased RBCs, and decreased platelets | Hematologic syndrome |
nausea, vomiting, diarrhea | Gastrointestinal syndrome |
first nausea and vomiting, then extremely nervous, confused, loss of normal senses, seizures, ataxia, lethargy | CNS syndrome |
the most radiosensitive macromolecule | DNA |
more sensitive to radiation when irradiated in an oxygenated state | Tissue |
the rate at which energy is transferred from ionizing radiation to soft tissue | Linear Energy Transfer (LET) |
RBE for x-ray | 1 |
LET increases the biologic damage increases | Relative Biological Effectiveness (RBE) |
Radiosensitivity varies with maturation and metabolism | Law of Bergonie and Tribondeau |
high sensitivity to radiation | young tissue |
High metabolic rate tissues | more radiosensitive |
Tissue with a high proliferation rate | more radiosensitive |
Stem cells | radiosensitive – more mature cells are less sensitive |
Late effects (delayed) presents at 6 months or more | Leukemia, Malignancies, Local Tissue Damage, Shortening of lifespan and Genetic Damage |
concerns imaging instrumentation and equipment maintenance | Quality Control |
Make sure the film is not outdated | Quality Control |
Screens are cleaned | 4x/year |
concerns patient care and image quality | Quality assurance |
How many retakes were taken | Quality assurance |
Is the patient getting the right study for the problem | Quality assurance |
mAs controls | radiation quantity, film optical density, and patient dose |
A short exposure time reduces | motion blur |
KVp controls | radiographic contrast |
Increasing filtration causes | a reduction of the quantity of x-ray photons but increases the quality of the radiation |
Increasing the voltage ripple causes | a decrease in both the quality and quantity of the x-ray radiation |
Increasing the focal film distance | decreases the quantity of radiation at the film but results in no change in the quality of the radiation |
Increasing mAs or s causes | an increase in the quantity of radiation but no change in the quality of the radiation |
Increasing kVp causes | an increase in both the quality and quantity of x-ray radiation |
If x-ray too light need to | increase mAs |
unequal magnification | Distortion |
the ability of an image receptor to respond to a low x-ray exposure | Speed |
wide latitude | Long gray scale |
describes the amount of the shades of gray | Latitude |
narrow latitude | Short gray scale |
equal to the slope of the straight line portion of the characteristic curve | Radiographic contrast |
determined by the size, shape, and x-ray attenuating characteristics of the subject and the energy (kVp) of the beam | Subject contrast |
contrast – inherent in the film | Image receptor |
Latitude and contrast are | inversely proportional |
Use a long source to image distance (focal film distance) | minimize magnification |
Use a short object to image distance (object film distance) | minimize magnification |
image size/object size | Magnification factor (MF) |
optical density due to development of silver grains that contain no useful information | Fog density |
optical density on unexposed film – due to composition of the film and the dye that is added to the base | Base density |
relationship between intensity of exposure and blackness of the film after processing | Sensitometry |
due to the random nature of x-ray photons | Quantum mottle |
due to phosphor size on the screens | Structure mottle |
due to the distribution and size of the silver halide crystals | Film Graininess |
Scale of contrast | # of shades of gray |
known as an H and D curve | characteristic curve |
a graph of optical density and how it relates to exposure | characteristic curve |
Parts of characteristic curve | toe, straight line, shoulder |
If the slope is steep | it will show white and black and no grayness |
more horizontal the slope | tells us how much grayness it has |
straight line tells us | about the contrast |
the most important component of characteristic curve | the straight line |
Created by:
hakrrins
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