Stereography

Stereography 

It is technique in which three dimension radiograph is produced by two radiographs. To achieve this third dimension in a two dimensional plane,a pair of radiographs is taken with the x ray tube being moved a certain distance between the exposures.

Sterscopic radiographs are viewed using binoculars or stereoscope. The left shift of radiograph is viewed by the left eye and the right shift by the right eye.

In case of absence of stereoscope, two radiographs are place together on a view box and the left shift radiograph  is placed at the observers right then viewed with the left  eye and right shift at the left,then viewed with the right eye.

It is used to create three dimension radiographs in doubtful diagnosis of certain caeses like in skull and SI joint in past but not used now due to doubled radiation dose.

Prepared by:

Sarose Bhandari

Soft tissue radiography

Soft tissue radiography

It is a technique in which radiographic image of soft tissue is obtained with the use of comparatively low exposure factor then the actual exposure factor i.e use of low kvp and high mAs. The exposure time for the soft tissue radiograph is comparatively takes more so radiation protection is the must.

Uses:

Ø  In mammography

Ø  To demonstrate:

·         Low density foreign bodies

·         Soft tissue of neck

·         Cysticercosis(parasitic calcification)

·         Soft tissue ulceration

·         Calcification in arteries and tendons

·         Subcutaneous fat in nutrition surveys

·         Sublaxation of acromioclavicular joint

·         Subdeltoid fat layer changes in peritendinitis

Prepared by:

Sarose Bhandari

Multiple radiography

Multiple radiography

It is a technique in which two or more radiographs are produced by a single exposure.

Advantages:

Ø  Duplication of films

Ø  Any examination where both bone and soft tissue detail  is required

Ø  Investigation of placental site

Ø  Demonstration of trachea both suprasternally and retrosternally in lateral view of thoracic inlet

Ø  Reduction in patient dose

Ø  Multi section tomography

Ø  Process of spines in lateral views

Prepared by:

Sarose Bhandari

Macroradigraphy

Macroradigraphy 

It is the production of the enlarged image by x ray magnification. The divergence of the beam from a small source is used to magnify the image geometrically.

Requirements:

Ø  Fine focus of 0.1mm2 or less is ideal but 0.3mm2 focus can be considered as well

Ø  Short exposure time

Principles:

The degree of magnification obtained by the macroradiography depends on the ration of focus- film distance to focus-object distance.

Magnification: size of image/size of object

Magnification: focus-film distance/focus-object distance

If the object is midway between the focus and the film the magnification on the radiograph is  twice then the orginal one i.e *2.

Uses:

Ø  In dacrocystography

Ø  In sailography

Ø  In skeletal views i.e carpal and tarsal bone particularly

Ø  Investigation of temporal bones

Ø  Investigation on neonatal heart disease

Microfocal macroradiography:

If higher digree of magnification i.e >*2  are required,microfocal tube with focal spot of between 10µ and 25µ is used which enables magnification up to *100 and *4 relatively.

Microradiography:

Microradiography is a term use for the radiographic examination of microscopic structures, e.g  specimens of breast following surgery.

A focal spot of less than 100µ is used and can demonstrate calcification as small as 2µ.

Preapared by:

Sarose Bhandari

High kvp technique

High kvp technique

It is a technique in which x ray image of a part of  subject with the application  of high kilovoltage(>kvp). With the use of high kvp range of scattered radiation increases so an effective grid of higher grid ratio is required,alternatively the air gap technique can be used with proper collimation.

Advantages:

Ø  Wide range of tissues can be visualized in one flim (main advantage)

Ø  Reduction in mAs aloows shorter time leading reduction in motion blur

Ø  Heating of x ray tube is reduced

Ø  There is greater exposure latitude

Ø  Radiation dose to patient is reduced

Ø  Allows more frequent use of fine focus

Disadvantages:

Ø  Special equipment is required

Ø  Grid with high grid ratio is required

Ø  Poor  detail and poor  contrast of the soft tissue

Ø   In some cases gonad dose increases like in chest radiography

Ø  There is risk of over penetration

Ø  Bone detail in skeletal work is poorly rendered

Uses:

Ø  In obstetric radiography,reduces  mother and feotus radiation dose

Ø  In HSG,reduces gonad dose

Ø  In Barium series and rapid serial examinations,less heating of tube due to shorter exposure time

Ø  In lateral view of lumbosacral spine

Prepared by :

Sarose Bhandari