direct vision fluoroscopy

introduction

In radiography, the image is formed by passing through an X-ray patient and falling on a detector or film. And this gives a sstatic image. Fluoroscent screens are used as detector in fluoroscopy. A live x-ray image of body functioning and motion is obtained by fluoroscopy. It is used to get the real-time moving image of the internal structure of the patient.

direct vision fluoroscopy

Fluoroscopy is a dynamic imaging system, in which the moving organ can be viewed with the help of X-rays. During this time x-rays are constantly in ON condition.

Fluoroscopy system has many applications. like -

• Photo-spot imaging
• Spot film acquisition
• Digital subtraction angiography
• Endoscopic examination
• Lithotripsy
• Cine-radiography

Depending on the technology, the fluoroscopy machine is of the following types -

• Direct Vision Fluoroscopy
• Image Intensifier Fluoroscopy (IITV)
• Flatpanel Detector Fluoroscopy

Direct Vision Fluoroscopy

It is also called conventional fluoroscopy. It was discovered in 1896 by Thomas A. Edison. In this, an image is formed by falling of x ray on the fluoroscopic screen, which can be seen directly with the eyes. The Radiologist stands behind this fluoroscent screen and sees this live image.

This fluoroscent screen is made by coating of zinc cadmium sulfide (ZnCdS) on a lead glass. Green light comes out when xray falls on zinc cadmium sulfide. Hence it is also called Green screen. Radiologist looks at this image in the dark room with the help of red goggels. When X-rays fall on the Thick phosphor layer, it converts it into visible light in the same proportion, but the brightness of this image is very low.

Early fluoroscope

This type of fluoroscopy continued to be used until 1950. Image After the advent of intensifier fluoroscopy it was discontionue for the following reason.

• The light output of a fluoroscent screen is very low for any x-ray exposure.
• Screen's light conversion efficiency is very low and spatial resolution is very low.
• Due to the narrow viewing angle being about 6 °, the radiologist is able to see only a part of the light coming from the screen.

red goggles

• In low light the visual acuity or visual acuity of the eyes is 10 times less. Hence the contrast of the fluoroscopic image is only 1/10 of the contrast of the radiographic image.
• The image is very faint. So, it can only be seen with the help of red goggles in the dark room.
• In the fluoroscopy procedure, the patient and radiologist and staff have higher radiation dose.
• Fluoroscopy procedure room requires complete darkness.
• Only one person can see the image on a Fluoroscent screen at a time.