Beam Restrictions Flashcards
What is the purpose of beam restriction/coning down to the part of interest?
- To ____ the amount of ____ being ___ to ____
- To produce _____
In order to achieve this, we must…
What is the purpose of beam restriction/coning down to the part of interest?
- To REDUCE the amount for TISSUE being EXPOSED to RADIATION
- To produce QUALITY IMAGES
In order to achieve this, we must…
CONTROL SCATTER RADIATION
What factors contribute to Compton scatter?
- ____
- ____ of ___ material (__ size and patient __)
What factors contribute to Compton scatter?
- KVP
- VOLUME of IRRADIATED material (FIELD size and patient THICKNESS)
Field Size
Decreased field size decreases ______
- decreases ___
- shortens ___ of ___ (more ___/___ ___ or less ____)
Field Size
Decreased field size decreases BEAM QUANTITY
- decreases SCATTER
- shortens SCALE of CONTRAST (more BLACK/WHITE SCALE or less GRAY TONES)
Field Size
Increased field size increases ___ of ____ being ____
- results in increased ___
- results in ___ scale of ___
Field Size
Increased field size increases VOLUME of TISSUE BEING IRRADIATED (EXPOSED)
- results in increased SCATTER
- results in LONGER scale of CONTRAST
Patient Thickness
- Thicker body parts produce…
- Denser body parts produce…
Both of these increase the ___ of ___ the x-ray beam ___ as it ___ through ___
Patient Thickness
- Thicker body parts produce MORE SCATTER
- Denser body parts produce MORE SCATTER
Both of these increase the NUMBER of INTERACTIONS the x-ray beam UNDERGOES as it PASSES through BODY
Beam Restrictors
Device used to ___ the _____ to __ part of ___
Name the different beam restrictors.
Beam Restrictors
Device used to SHAPE the X-RAY/PRIMARY BEAM to FIT part of BODY
Name the different beam restrictors.
- CONE OR CYLINDER
- APERATURE DIAPHRAGM
- COLLIMATORS
- ANCILLARY DEVICES
Aperature Diagraphm (first collimator we had)
- attached to…
- very simple ______ with a ___ out to _____
- diaphragm ___ cut out _____
Aperature Diagraphm (first collimator we had)
- attached to X-RAY TUBE
- very simple - FLAT LEAD SHEET WITH A HOLE CUT OUT TO MATCH FIELD SIZE
- diaphragm LEAD CUT OUT UNIQUE SHAPES
Aperature Diaphragm
Cones and Cylinders
- Used for greater ____ of ___ in ___ area
- Reduces…
- Reduction in scatter makes images “appear” ____
note: DO NOT confuse visibility of detail with recorded detail
Cones and Cylinders
- Used for GREATER VISIBILITY OF DETAIL IN SMALL AREA
- Reduces PENUMBRA
- Reduction in scatter makes images “appear” SHARPER
note: DO NOT confuse visibility of detail with recorded detail
Penumbra
area of ___ around ___ lines
Penumbra
area of UNSHARPNESS AROUND THE STRUCTURAL LINES
Extension Cones and Cylinders
What size are cylinders? ___ size ____
What does the shape of the cone do and what does it allow?
Extension Cones and Cylinders
What size are cylinders? SAME SIZE ALL THE WAY DOWN
What does the shape of the cone do and what does it allow? FLARE OUT AND ALLOWS DIVERGENCE
Applications of cones and cylinders can be used in… (3 things)
Applications of cones and cylinders can be used in… (3 things)
HEAD WORK - SINUSES OR SKULLS
SPINE WORK - SPOT FILMS (EX- L5, S1)
CROSS TABLE HIP
The collimator is a _____-like ______ device with ___________ attached to the x-ray _________
The collimator is a BOX-like BEAM-RESTRICTING device with ADJUSTABLE LEAD SHUTTERS attached to the x-ray TUBE HOUSING PORT
Collimator
Variable aperature = _____ (what size?)
______ and ____ of field size
Upper shutters/entrance shutters help remove off _____
Lower shutters the one that ____ adjusts
- lower shutters consist of ___ shutters at ___ angles to each other which moves in ____
Collimator
Variable aperature = ANY SIZE (what size?)
LENGTH and WIDTH of field size
Upper shutters/entrance shutters HELP REMOVE OFF FOCUS RADIATION
Lower shutters THE ONE THAT TECHNOLOGIST ADJUSTS
- lower shutters consist of LEAD SHUTTERS AT RIGHT ANGLES TO EACH OTHER WHICH MOVES IN OPPOSITE PAIRS
Positive Beam Limiting Device or PBL
- _____ collimator
- _______ activate the collimator’s ____ to ___ the size of the ___
1974-1993 - Federal Law required all _________ to have ________
Positive Beam Limiting Device or PBL
- AUTOMATIC collimator
- BUCKY SENSORS activate the collimator’s SHUTTERS to CONE TO THE SIZE OF THE IR
1974-1993 - Federal Law required all FIXED (NONPORTABLE) COLLIMATORS to have PBL DEVICES
Positive Beam Limitation Device (PBL)
_________ used with bucky tray (table or upright)
automatically adjusts ___ size to ___ size
- will not allow ___ fields
- will have a method to ______ size
Positive Beam Limitation Device (PBL)
AUTOMATATED COLLIMATOR SYSTEM used with bucky tray (table or upright)
automatically adjusts FIELD SIZE TO FILM SIZE
- will not allow LARGER FIELDS
- will have a METHOD TO REDUCE FIELD SIZE
“Collimation Rule”
The ___ of the collimated x-ray field should be adjusted (collimated) to… (2 things)
- smallest ______ that will include the ___ of the __ to be ___
- but never ____ than the size of the ___
“Collimation Rule”
The SIZE of the collimated x-ray field should be adjusted (collimated) to… (2 things)
- Smallest REASONABLE SIZE that will include the PORTION of the BODY to be IMAGED
- But never LARGER than the SIZE of the FILM
What are the functions of the collimator? (5 things)
- shape and size beam
- light localization of beam
- tube locking controls
- detent controls
- accessory attachments
Light Field
uses a ____ reflected off of a ____ to project _____ of the x-ray ___
- proper adjustment of _____ is necessary to accurately display _____ of ____ field
- note: the collimator system counts as part of ________*
Light Field
uses a LIGHT reflected off of a MIRROR to project COVERAGE of the x-ray BEAM
- proper adjustment of MIRROR is necessary to accurately display LOCATION of EXPOSURE field
- note: the collimator system counts as part of ADDED FILTRATION (MIRROR)*
Control of Scatter Using Beam Restricting Devices
Ideally, beam restrictors decrease ______ to ____ of interest
- unneccessary ___ exposure ____
- ____ decreases
- _______ shortens
- _______ increases
All good things!
Control of Scatter Using Beam Restricting Devices
Ideally, beam restrictors DECREASE FIELD SIZE to ANATOMY of interest
- unneccessary TISSUE exposure DECREASES
- SCATTER decreases
- SCALE OF CONTRAST shortens
- VISIBILITY OF DETAIL increases
All good things!
Decreasing Part Thickness
______ are used to improve ________ and ______
- ______ patient _____
- results in ______
- brings ____ closer to film
- utilized in ______
Decreasing Part Thickness
COMPRESSION DEVICES are used to improve SPATIAL RESOLUTION and CONTRAST
- DECREASE patient THICKNESS
- results in LOWER PATIENT DOSE
- brings TISSUE closer to film
- utilized in MAMMOGRAPHY
Ancillary Devices
- lead ____ (ex -___)
- lead ____ (ex- attach to _____)
Ancillary Devices
- lead BLOCKERS (ex - SHIELDS)
- lead MASKS (ex- attach to COLLIMATOR)
