Beam Limiting Device (BLD)
It's purpose is to limit the size of the beam and area of exposure to patient, thereby reducing the harmful effects of scatter and to improve image contrast.
1.) Aperture Diaphragm
2.) Cones and Cylinders
3.) Variable Aperature Collimator
What are the types of beam limiting devices?
___is the simplest type of all BLD's.
Aperture diaphragm is commonly used at dedicated ___.
Disadvantage of aperture diaphragm is its ___?
Lead or a Lead Lined Plate
In the aperture diaphragm there is ___ placed directly below the window of the x-ray tube.
The ___ of the aperture diaphragm is designed to just cover less than the size of the image receptor used.
An ___ of the aperture diaphragm should be visible on each edge of the radiograph.
Cones and Cylinders
___ are modifications of the diaphragm.
Usually the useful beam is in a ___ shape.
Cones and cylinders are widely used in ____ radiography.
Cones and cylinders are difficult to ___.
Cones and cylinders must be aligned with the ___.
Variable Aperture Collimator
___ is the most common BLD.
Variable Aperture Collimator is the most ___ BLD.
NCRP guideline: Variable Aperture Collimator must be accurate to within ___% of the source-to-image distance.
Positive Beam Limiting (PBL) Device
Most variable aperture collimator are automatically adjusted when a film is inserted in a bucky, called a ___.
Positive Beam Limiting (PBL) Device are equipped with usually two or more ___ stacked one above the other.
Mirror and a Light Bulb
Positive Beam Limiting (PBL) Device uses a ___ as a guide for projection of the field know as a light localization apparatus.
The filtration afforded by the glass envelope, insulating oil and glass window.
0.5 mm aluminum
Inherent filtration is usually ___ equivalent.
With age, filtration ___.
As filtration increases, so does beam ___, but quantity is decreased.
Sheets of aluminum placed between the protective tube housing and external housing.
___ Filtration attenuates more low energy than high energy x-rays.
1.) High energy
2.) Greater penetrability
3.) Higher quality beam
Added filtration results in?
Added filtration affects x-ray ___.
Equals inherent filtration plus added filtration.
___ equates to decreased skin dose.
___ is decreased with the tissue.
Shorter ___ time results in decreased patient dose and reduces the chance of motion.
Grid is generally used on body parts greater than ___ cm. in thickness.
Use of grid increases ___.
Higher grid ___ results in higher patient dose.
Medium or High
___ speed Film/Screen: 8-10 cm. body part thickness.
Grid: Greater than ___cm. body part thickness
1.) Proper technique
2.) Proper positioning
3.) Appropriate marker
4.) Correct patient identification
Methods used to avoid repeated radiographs?
Use ___ film/screen combination.
1.) Digestive organ motion
2.) Cardiac motion
3.) Muscle Spasms
Shorter exposure time is used for involuntary motion such as?
Quality Control Program
Proper processor maintenance, Proper equipment testing and maintenance.
Radiographic examinations should be performed only during the first 10 days following the onset of the menstrual period.
Added Plus Inherent Filtration
How do you calculate total filtration?
What film/screen combination must be used for parts lesser than 8 cm?
To reduce the radiation exposure to the reproductive organs.
What is the purpose of patient shielding?
An effective means of reducing the risks of genetic defects for the whole population.
What is the importance of patient shielding?
1.) Flat contact
2.) Shadow shield
3.) Shaped contact shield
What are the types of shielding devices?
Flat piece of plastic covered lead, Similar to lead apron.
___ is attached to the x-ray tube.
Shadow shield is ___ over the area being radiated.
Align the shadow shield with the ___ for accurate placement to avoid areas of interest.
Shaped Contact Shield
____ consist of a radiopaque material contoured to enclose the testicles.
Cleaned and Reused
Shaped contact shield can be ___.
Athletic Supporters or Jockey
Shaped contact shield is available in ___ style.
Patient shielding should be considered for all patients, especially children and those who are potentially ___.
Gonadal shielding should be used when the gonads lie in or within ___cm of a well-collimated field or the useful beam.
Positioning and Beam Collimation
Proper patient ____ should not be relaxed when gonad shields are in use.
Patient shielding should only be used when it does not ___ with obtaining the required diagnostic information.
AP or PA
Flat contact: ___ views.
Shadow shield: ___ or incapacitated patient.
1.) AP or PA,
Shaped contact shield: ___ views, Selected fluoroscopic exam.
2.) Hip (Except oblique)
3.) Upper femur
Shield males in what exams?
1.) Retrograde urethrograms
2.) Voiding cystourethrograms
3.) Oblique views of the hip
4.) Visualization of the rectum
5.) Symphysis pubis
Shielding will interfere with what exams?
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