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Chapt 10 Radiology

X-Ray Darkroom and Film

QuestionAnswer
What is a TECHNIQUE CHART Listings of exposure factors to be used on various radiographic exams
A well contructed technique chart has trusted techinques that produce films with what? Adequate DENSITY & CONTRAST
A Technique chart provides the following information mA - kVp and the (SID) Source-imaging distance
The TOOL USED FOR BODY MEASUREMENT IS CALLED A CALIPER
T/F - TECHNIQUE CHARTS ARE BASED ON THE MEASUREMENT OF THE BODY PART TO BE RADIOGRAPHED TRUE
Manual technique charts are based on patient part measurements obtained using an x-ray caliper; These measurements are expressed as: Thickness, in centimeters
What are the 2 main types of Technique Charts that can be used - Variable kVp Chart - Fixed kVp Chart
Of the 2 Types of Technique Charts which one is the most preferable? THE FIXED kVp Chart
The kVp that is sufficient to penetrate the body part adequately without excess exposure to the patient is called? OPTIMUM kVp
What factors need to be considered when seleting the mA station? Exposure time and Focal Spot Size
The advantages of using a variable kVp technique chart are? - lower overall image contrast - improved visibility of detail - ability t make small incremental changes in exposure technique
Why should the SMALL FOCAL SPOT be uses as much as possible? it provides a better image sharpness
How should exposure factors be adjusted when there is a liklihood of motion Increase mA and Decrease Exposure Time
What is the fule of thumb on selecting mA and Exposure time use the highest possible mA with the shortest possible time for the mAs and focal spot size you want
The general guidelines for focal spot selection is as follows
Uses: 50 - 100 mA (small focal spot) Upper Extrmities: finger,hand,wrist,forarm,elbow,humerus,shoulder,scapula and clavical
Usues: 200mA (upper limit for small focal spot) Thoracic Spine, Lumbar Spine, Abdomen, Skull
Uses: 300+ mA (large focal spot) Chest, any procedure where the patient cannot hold still
20 mAs @ 68kVp = SHORT SCALE (high) CONTRAST
The Relationship between mAs & SID is DIRECTLY PROPORTIONAL
WHAT IS GCF GRID CONVERSION FACTOR
NO GRID IS = TO 1
5:1 GRID IS = TO 3
8:1 GRID IS = TO 4
12:1 GRID IS = TO 5
16:1 GRIS IS = TO 6
What is the relationship between mAs & RS SPEED INVERSLY PROPORTIONAL
A fiberglass cast will require an increase of mAs of how much? NO CHAGE REQUIRED
Which of the following x-ray projections can benefit from the use of compensating filters Anteroposterior (AP) throacic spine Axiolateral Hip
T/F= Once established on the technique chart, the kVp should never be changed unless contrast need to be changed? TRUE
If a compensating filter is used with a body part that has significantly varying tissue density, such as the shoulder in AP projection, two separate exposures will still hanve to be made FALSE
The use of compensating filters can help reduce the entrance skin exposure TRUE
What is RADIATION PROTECTION
What is SSD DISTANCE FROM RADIATION SOURCE (X-RAY TUBE) TO PATIENT SKIN
WHAT IS RAD UNIT MEASURING ABSORBED DOSE
What is NONSTOCHASTIC Proportional in severity to the dose of radiation
Conventional unit of radiation exposure is called ROENTGEN
Whole Body Dose EQUIVALENT DOSE
What is a DEVELOPMENT OF MALIGNANT DISEASE CARCINOGENESIS
EXC WHAT DOES ALARA STAND FOR As Low As Reasonably Achievable
WHAT DOES ALARA MEAN Radiation exposure should be limited to the lowest possible levels
What is a GONAD SHIELD A device to prevent unnecessary radiation to reprodcutive organs
WHAT DOES "REM" STAND FOR ROENTGEN EQUIVALENT MAN
WHAT IS USED TO MEASURE OCCUPATIONAL EXPOSURE? REM & SIEVERT
MILI = 1/1000
mR = MILLIROENTGEN
MRAD = MILLIRAD
millirem =
WHAT DOES ESE STAND FOR ENTRANCE SKIN EXPOSURE
What is the jelly like material that contains MOSTLY WATER and the ORANGELLES, which are small structures that carry out cellular functions CYTOPLASM
WHAT IS AT THE CENTER OF THE CYTOPLASM NUCLEUS
WHAT DOES THE NUCLEUS CONTAIN NUCLEOLI
The Nucleoli contains how many pairs of chromosomes 23 pairs that are thread like spools of DNA (deoxyribonucleic acid)
WHEN X-RAYS INTERACT WITH ATOMS THEY MAKE UP CELLS
When ionization occurs what does this mean? Electrons are released from thier orbits
Even though ionization may occur in any part of the cell, interactions are classified as being either a direct hit or an indirect hit
What does a direct hit refer to when x-ray photons interact with DNA DIRECTLY - therby breaking the molecules
What does an INDIRECT HIT refer to when x-ray photons interact with the water molecules thereby causing a chemical reaction that forms free radicals
When the free radicals interact with DNA or combine with other molecules what happens? It produces a toxic substance that damages the DNA
The relative sensativity of cells to radiation depend on 4 characteristics. What are they? AGE - DIFFERENTIATION - METABOLIC RATE - MITOTIC RATE
CELLS THAT ARE HIGHLY SENSITIVE TO RADIATION ARE? Blood Cells - Skin & Mucous memebranes - Thyroid & Breast - Embyonic - Reproductive (OVA & SPER)
CELLS THAT ARE LESS SENSITIVE TO RADIATION ARE? NERVE -MUSCLE - BONE
What are the 2 effects of radiation exposure on the body NON-STOCHASTIC OR STOCHASTIC
WHAT IS NON-STOCHASTIC EFFECTS - Occurs at HIGH DOSES OF RADIATION - BIOLOGICAL EFFECTS ARE PREDICITABLE - SEVERITY IS PROPORTIONAL TO THE DOSE
WHAT IS STOCHASTIC EFFECTS THOSE THAT OCCUR AT LOWER DOSES OF RADIATION - SUCH AS AMOUNTS RECIEVED FROM XRAY PROCEDURES- ARE RANDOM AND UNPREDICTIBLE - PROPORTIONAL TO DOSE BUT SEVERITY IS UNRELATED TO DOSE -
WHAT ARE SHORT TERM EFFECTS OBSERVERED 3 MONTHS - ARE ASSOCIATED WITH HIGH RADIATION DOSES (>50Gy)-they are hematologic effects - gastrointestinal effects - & central nervous systems effects
WHAT ARE THE LONG TERM EFFECTS Those NOT OBSERVED UNTIL SEVERAL YEARS AFTER EXPOSURE - EFFECTS ARE ASSOCIATED WITH LOWER DOSE OF RADIATION OVER TIME
What is SHORT TERM SOMATIC EFFECTS USUALLY High Doses - Non-Stochastic -USUALLY SEVERE
SHORT TERM SOMATIC EFFECTS HAVE BEEN OBSERVED IN Persons undergoing radiation therapy,Victims of nuclear accidents, and thosed exposed to atomic weapons
WHAT ARE SOME OF THE EFFECTS Ertherma (reddening of the skin), seizures followed by coma and death, raidation sickness are all examples of short term effects
IS A XRAY MACHINE CAPABLE OF PRODUCING ENOUGH RADIATION TO CAUSE SHORTERM SOMATIC EFFECTS NO
What is LONG TERM SOMATIC EFFECTS Occur with lower doses given over time - they are stochastic - usually less severe but can result in death
What are some of the effects? Cataractogensis (clouding of the lens of the eye), Carinogenesis (malignant disease), Leukemia (cancer of the blood cells), and life span shortening.
Can excessive exposure to diagnostic x-rays over a period of time cause long tern somatic effects? YES
The average american is exposed to how many mrem (milirems)of radiation per year. 360 (3.6 mSv)
82% of of this exposure is from naturally occurring sources such as , such as space, the earth and from radon gas Milirem
Does exposure to diagnostic x-rays carry any risk? yes some
What is the number one cause of unnecessary radiation exposure to patients? REPEAT EXPOSURES
Limiting the radiation field size through __________ protects patients from unnecessary exposure. COLLIMATION
Operators should use what size field that will cover the are of anatomy to be examined the smallest radiation field
USING WHAT TECHNIQUES ALSO REDUCSES PATIENT XPOSURE LOW mAs and HIGH kVp techniques
T/F - Gonad shield should be used on all adults with reproductive potential? TRUE - THOSE UNDER THE AGE OF 55
T/F - Gonad shield should be used on all children since thier cells are more sensitive to radiation than adults TRUE
THEREFORE WHAT AGE GROUP SHOULD GONAD SHIELDING BE USED ON AGES 1 - 55 YEARS OF AGE
The federal goverment and state agencies recommend that gonadal shields consist of at lease ______ mm of lead equivalent to be effective 0.5mm
There are 2 types of Gonadal shiels, what are they SHADOW SHIELD AND THE CONTACT SHIELD
WHAT IS THE MOST COMMON TYPE OF SHIELD USED CONTACT SHIELD
WHAT ARE THE 3 MAIN PRINCIPAL MEASURES USED TO PROTECT AN XRAY MACHINE OPERATOR TIME - DISTANCE - SHIELDING
WHAT IS A DOSIMETER IT IS A DEVICE WORN BY RADIATION WORKERS THAT MEASURE OCCUPATIONAL EXPOSURE
WHAT WERE THE ORIGINAL DOSIMETERS FILM BADGES
IN ORDER TO GET AN ACCURATE READING WHERE SHOULD THE DOSIMETER BE WORN? COLLAR LEVEL ON THE FRONT OF THE BODY
IF WEARING A LEAD APRON WHERE SHOULD YOU WEAR THE DOSIMETER? IT SHOULD BE WORN ON THE OUTSIDE
WHAT IS THE OCCUPATIONAL EXPOSED - The UPPER DE limit is 5 REM (.05 Sv) per year
The DE LIMIT applies to WHOME? Workers over the age of 18 and women who are NOT pregnant
When does the greatest risk of fetal development during the 1st trimester
WHAT IS THE DE (dosage equivalent) for a pregnant worker? 0.5mm (.0005 Sv)each month
Pregnant women must wear how many dosimeters 2
Where must pregnanat women wear both of the dosimeters A RED ONE AT THE COLLAR ON THE OUTSIDE OF THE LEAD APRON AND A 2ND GREEN ONE UNERNEATH THE LEAD APRON
Created by: spoon6464