mi 120 unit 3 Flashcards
holistic patient care
treat the patient as a whole person rather than a body part
effective communication and body language
-introduce yourself
-address the patient properly
-ease patient stress and anxiety
-understanding and dignity
-clear and concise instructions
-increase their cooperation
-give them time to ask questions
-gain their trust
-be professional, be present and watch body language
-reduce repeat exposures
involuntary motion
caused by muscles, not controlled
-heart, digestive, chills, tremors, spams, pain, withdrawl
how do you correct involuntary motion
reduce exposure time and increase image receptor speed
voluntary motion
controlled motion
-lack of control caused by age, breathing, anxiety, discomfort, fear
how do you correct voluntary motion
gaining the patients cooperation and use of proper immobilization
piggostat
mainly for chest. xray in babies younger than 2, baby needs to be able to hold their head up
octostop
used to perform in fluro; good for rotation for toddlers
sponges and sandbags
sponges are radiolucent
sandbags are radiopaque
mummy wrap
immobilization for babies who keep their hands and arms near their head
tape
never stick the tape to patients skin
radiolucent plexiglass
plastic like glass that we can xray through
non-radiology employee holds patients because
we need someone to hold because we already are getting exposed enough by taking the xray in general
beam limiting device
limits the primary beam to a smaller area; decreases exposure by reducing the amount of tissue exposed and reduces SCATTER
aperture diaphragm
flat lead with a hole cut in it and placed below the window
-rectangular in the most common, can be square or round
-reduced SCATTER
Cones
circular metal cylinder that connect to front of the tube and limits the size of the beam
-can be flared or straight and 10-12 inches away
-mostly used in dental radiography but can be used for heel, skull, and spine images
what replaced cones
collimators
collimators
also called light localizing variable aperture rectangular collimator
-SHOULD NOT BE OPENED LARGER THAN BODY PART
-can reduce exposure by 20-30%
-dont over collimate (make it too small)
-2 sets of shutters 90 degrees from one another
near (upper)
located close to a window
reduce exposure from off focus radiation
far (lower)
located close to light source
confines the beam to area of interest
skin sparing
minimizes skin exposure by requiring a 15 cm distance from skin to collimator
-can be achieved by spacer bars mounted on the tube
PBL- positive beam limitation
electronic sensors in the bucky that senses the size of the IR that is used and opens the collimators appropriately
–slites or pegs
-reduces human error
-aka automatic collimator
filtration
hardens the beam by cleaning up low energy
reduces patient exposure to skin and superficial surface
reduces absorbed dose
lower energy photons provide no detail to the image
what is the total filtration in the housing
2.5 mm AL (aluminum) equivalent for units that operate above 70kVp
inherent
0.5 mm AL
made up of glass envelop, insulating oil, and glass window
added
2.0 mm AL
made up of sheets of AL added outside the glass window above the collimator
-can be accessed by a service person and can be changed as tube ages
mobil and fluro require what
2.5 mm AL filtrarion
NCRP #102 list minimum requirements for filtraion
what act states xray adequate filtration
radiation control for health and safety act of 1981
HVL
half value layer
-measures beam quality or effective energy of the beam
-measured once a year by a physiscit
AAPM stated what
american association of physicists in medicine
april 2019
shielding of patient gonadal or fetal shielding during diagnostic imaging should be discontinued
what organs need reduced exposure
eye, breast, reproductive
gonadal
first step to gonadal protection is proper collimation
-due to location of gonads, females receive 3x more exposure
placement of contact of shadow shields for men and women
female- at the level of ASIS and should extend 1/2 inches above the superior rim of the pubic bone
male- place shield just below the pubic bone
flat contact/ figleaf
most effective in AP or PA view
shadow
needs to be carefully placed, not useful in fluoro
shaped
contoured to male anatomy, placed by patient, not useful with PA projection
half shield
used for gonadal protection of patient, covers front or back of patient and is attached by velcro strap or on wheel
compensating filters
used when x-raying a part that has varying thickness to reduce dose and provide a uniform density across the image
-decreases the entrance skin exposure
-constructed or aluminum or lead arcylic that is attached to the bottom of the collimator
wedge
used for foot or spine
trough
used for chest
ferlic
used for hips (only)
boomerang
used for shoulders (gos outside shoulder an cleans up access tissue)
kVp
the wavelength (speed) going through the body
maximum possible energy of a photon that exits the xray tube
-indirectly proportional to patent exposure
mA/milliamperage
of xrays that are created
-measurement of xray tube current or the number of electrons crossing the tube from cathode
-directly proportional patient exposure
mAs/ milliampere seconds
controls the amount of radiation produced by the xray tube
mA X seconds = mAs
directly proportional to patient exposure
AEC/ automatic exposure control
the cells that are selected on the operating console that will automatically select the mA according to cell selection and body part
-sets the appropiate mA for the body part being xrayed
increase what and decrease what
kVp; mAs
imaging receptor
increase in imaging receptor speed, decrease patient exposure by t decreases sharpness
correct processing
inadequate processing results in image reports
radiographic grids
-rule of thumb is to use the grid when part of thickness is over 10 cm
-removes scatter that comes form the patient before they reach the image receptor
-grids increase patient dose but improves the quality of the image which provides a better diagnosis
-use the lowest grid ratio appropriate for the body part
air gap technique
alternative to using a grid to clean up scatter
-patient is placed 6-10 inches away from the image receptor with a 10-12 feet SID
repeat images
any image that must be done more than once due to human or mechanical error
-patient receives a double dose
unnecessary exposure
pre admission, pre employment, routine health check ups, screening for TB , check for disease
mobil xrays
minimal source to skin distance on a mobile fluoroscopy unit is 12 inches or 30 cm
-the smaller the source to skin distance, the larger the entrance exposure
fluoro distances
NCRP states 15 inches or 38 cm for fixed units and 12 inches or 30 cm for mobile units
-audible alarm at every 5 minutes
-exposure rate limit-federal regulations for table top exposure is 88 mGy per minute
fluoro exposure switch
called a dead man switch
-foot pedal requires direct pressure to continue with fluoro
fluoro guided positioning (unethical)
using fluro to: determine if you are positioned appropriately before taking an image
DAP (dose area product)
newer fluoro systems provide the sum of the air kerma over the exposed are the patient
c-arm fluoroscopy
used in: OR, cardiac cath, IR
-12 inches or 30 cm minimal distance to the patient
-c-arm should be positioned with the II on top (reduced scatter)
cinefluoroscopy
used in cardiography and neuro-radiography
-reduce patient exposure and works like a movie
interventional radiology
invasive sterile procedures performed by a physician under fluoro
-FDA requires documentation in the patient chart if skin dose os 1-2 Gy
-federal regulations for table top exposure of high level control fluoro are 176 mGy per minute
radiation dose measurements
entrance skin exposure (ESE) includes skin and glandular
-skin dose: absorbed dose to the most superficial layers
-Gonadal dose: US dose is 0.2 mSv
-bone marrow dose
pregnant patients
-asking LMP
-10 day rule: xrays should be done within 10 days of onset of period
-ACR’s position
-10-25 rad rule (less then 10 and 25 is too high)
mammography
utilizes low kVp, limit number of projections, adequate compression, avoid axillary exposure unless ordered by radiologist
CT
-doses are higher than diagnostic radiology
-shielding is not utilized because of the nature of the exposure
-collimators are very tight in CT
pediatric patients
longer life span can increase chances of developing a radiation induced leukemia or radiologic malignancy such as lung or thyroid
morbid obesity
skeletal anatomy and organ size does not change except possibly: thoracic cage expanded 2”, stomach may slightly be larger, colon may spread out
-increase the image receptor to increase penetration of the xray beam
image gently
CT- one size does not fit all
digital- back to basics
NM- go with the guidelines
fluoro- pause in pulse
AIR- step lightly
NCRP dose limits
annual effective dose is 50 mSv
cumulative effective dose is age in years X 10 mSv
ALARA- collimate, technique, shielding and minimize repeats
reducing occupational exposure
avoid repeats, collimation, cumulative timer
stand 90 degrees from the patient
pateint is a source of scatter radiation
-3 feet or 1 meter from the patient
what is the scatter radiation to tech ratio
1/1000 the intensity
filtration
non useful low energy photons are removed, less scatter
exposure factors
controls scatter
correct image acquisition
reduces repeats
high speed image receptors
high speed systems use smaller exposures which causes less scatter
beam limiting devices
reduces scatter
pregnant personnel
after declaring, the second baby badge is used worn at waist level
-0.5 mSv in one month
-5 mSv for the entire pregnancy
-lead apron is worn inside the apron at waist level
-maternal tissue decreases fetus dose by 30%
types of radiation
primary radiation- useful beam, emerges directly from the tube collimator
scatter radiation- highest dose to the technologist; primary beam passes through matter and goes in various directions
leakage radiation- escapes the tube housing
protective structural shielding
usually lead or concrete
primary protective barrier- located perpendicular to primary beam travel
-prevents direct or unscattered radiation from reaching personnel and general public
-for 130 kVp of peak energy a 1/16 inches of lead or 7 ft upward form the floor
secondary protective barrier
any wall or barrier that is never hit by the primary beam
-1/32 inch of lead or lead equivalent
-overlaps the primary barrier by 1.2 inch and extends to the ceiling
-control booth is regarded as a secondary barrier
-window is 1.5 mm lead equivalent
protective device requirements
lead apron- 0.5 mm lead(Pb) for fluoro, AIR or operatiing
gloves- 0.25 mm lead (pb)
neck and thyroid- must be 0.5 mm lead (pb)
protective eyeglasses-contains lead (pb)
protective tube housing
lead lined metal that protects personnel and patients from leakage and off focus radiation
-cannot exceed 1 mGy per hour at 1m away from housing
fluoroscopy
proper position to be standing- avoid scatter areas; stand behind the physician/ radiologist or RA
90 degrees from the patient
when wearing a thyroid shield
unprotected areas are getting 10-20 x more exposure
protective shield linings
apron- 0.25mm or 0.5mm
gloves- 0.25mm
thyroid- 0.5 mm
eyeglasses- 0.35 mm
protective lead curtain
0.2 mm lead equivalent
protects scatter radiation
bucky slot cover
0.25 mm lead equivalent
protects gonadal protection
isoexposure curves
dose from scatter radiation at 90 degrees/ 1 metter away= dose x 0.001
cord length should be long enough to stand 6 ft away
c-arm
properly orient the c arm with II on top
stand on the side of the patient during a lateral view
cardinal principles of radiation protection
time- amount of exposure is directly proportional to duration of the exposure
distance- most effective means of protection, it is indirectly proportional
shielding- absorbs most of the energy of scatter radiation (85% of effectiveness)
ISL
I1/ I2= (D2)2/ (D1)2
workload
radiation on time during a week
measured in mAs/week or mA-minute/week
use
amount of time the beam is directed at the structure
takes into account primary or secondary radiation
occupancy
time that the area is occupied behind a barrier
waiting room and empty courtyard
calculating barrier requirements
W x U x T
controlled
occupied by workers who are trained and wearing monitoring devices
maximum permitted equivalent dose is 100 mrem per week
uncontrolled
occupied by the geneal public
maximum ermitted equivalent dose is 2 mrem per week
radiation sign posting
radiation symbol that is magenta, purple or black on yellow background
