Beam Restrictions

Question 1

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…

Answer 1

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

Question 2

What factors contribute to Compton scatter?

• ____
• ____ of ___ material (__ size and patient __)

Answer 2

What factors contribute to Compton scatter?

1. KVP
2. VOLUME of IRRADIATED material (FIELD size and patient THICKNESS)

Question 3

Field Size

Decreased field size decreases ______

• decreases ___
• shortens ___ of ___ (more ___/___ ___ or less ____)

Answer 3

Field Size

Decreased field size decreases BEAM QUANTITY

• decreases SCATTER
• shortens SCALE of CONTRAST (more BLACK/WHITE SCALE or less GRAY TONES)

Question 4

Field Size

Increased field size increases ___ of ____ being ____

• results in increased ___
• results in ___ scale of ___

Answer 4

Field Size

Increased field size increases VOLUME of TISSUE BEING IRRADIATED (EXPOSED)

• results in increased SCATTER
• results in LONGER scale of CONTRAST

Question 5

Patient Thickness

• Thicker body parts produce…
• Denser body parts produce…

Both of these increase the ___ of ___ the x-ray beam ___ as it ___ through ___

Answer 5

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

Question 6

Beam Restrictors

Device used to ___ the _____ to __ part of ___

Name the different beam restrictors.

Answer 6

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

Question 7

Aperature Diagraphm (first collimator we had)

• attached to…
• very simple ______ with a ___ out to _____
• diaphragm ___ cut out _____

Answer 7

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

Question 8

Aperature Diaphragm

Answer 8

Question 9

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

Answer 9

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

Question 10

Penumbra

area of ___ around ___ lines

Answer 10

Penumbra

area of UNSHARPNESS AROUND THE STRUCTURAL LINES

Question 11

Extension Cones and Cylinders

What size are cylinders? ___ size ____

What does the shape of the cone do and what does it allow?

Answer 11

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

Question 12

Applications of cones and cylinders can be used in… (3 things)

Answer 12

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

Question 13

The collimator is a _____-like ______ device with ___________ attached to the x-ray _________

Answer 13

The collimator is a BOX-like BEAM-RESTRICTING device with ADJUSTABLE LEAD SHUTTERS attached to the x-ray TUBE HOUSING PORT

Question 14

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 ____

Answer 14

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

Question 15

Positive Beam Limiting Device or PBL

• _____ collimator
• _______ activate the collimator’s ____ to ___ the size of the ___

1974-1993 - Federal Law required all _________ to have ________

Answer 15

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

Question 16

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

Answer 16

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

Question 17

“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 ___

Answer 17

“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

Question 18

What are the functions of the collimator? (5 things)

Answer 18

• shape and size beam
• light localization of beam
• tube locking controls
• detent controls
• accessory attachments

Question 19

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 ________*

Answer 19

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)*

Question 20

Control of Scatter Using Beam Restricting Devices

Ideally, beam restrictors decrease ______ to ____ of interest

• unneccessary ___ exposure ____
• ____ decreases
• _______ shortens
• _______ increases

All good things!

Answer 20

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!

Question 21

Decreasing Part Thickness

______ are used to improve ________ and ______

• ______ patient _____
• results in ______
• brings ____ closer to film
• utilized in ______

Answer 21

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

Question 22

Ancillary Devices

• lead ____ (ex -___)
• lead ____ (ex- attach to _____)

Answer 22

Ancillary Devices

• lead BLOCKERS (ex - SHIELDS)
• lead MASKS (ex- attach to COLLIMATOR)