The radiographic grid consists of thin lead foil strips separated by transparent spacers that help reduce scatter radiation in x-ray images. Invented in 1913 by Dr. Gustave Bucky, grids work by absorbing most scatter radiation which arrives from multiple angles within the patient, while allowing primary radiation from the x-ray tube to pass through unaffected. Grids are characterized by their ratio of lead strip height to inter-strip distance and come in various patterns like linear, crossed, parallel or focused, with focused grids converging the strips at a line or point to further reduce scatter.

1. • The radiographic gridw consists of a series of Lead
foil strips separated by X-ray transparent spacers
• Invented by Dr. Gustave Bucky in 1913
• Most effective way of removing scatter radiation
from large radiographic fields

2. • Primary radiation is oriented in the same axis as the
lead strips and passes between them to reach the
film unaffected by the grid.
• Scatter radiation arises from many points within
the patient and is multidirectional, so most of it is
absorbed by the lead strips and only a small
amount passes between them.

4. • The interspaces of grids are filled either with
aluminum or some organic compounds.
• The main purpose of the interspace material is to
support the thin lead foil strips.

5. GRID RATIO
• Ratio between the height of the lead strips and the
distance between them.
• It is the parameter widely used to express a grid's
ability to remove scatter radiation.
• Higher the ratio, better is the grid function.

7. GRID PATTERN
• Orientation of the Lead strips in their longitudinal
axis.
• Pattern of the grid that we see from the top.
• 1)Linear grid
• 2)Crossed grid
• 3)Parallel grid
• 4)Foccussed grid

8. LINEAR GRID
• The lead strips are parellel to each other in their
longitudinal axis.
• Their major advantage is that they allow us to angle
the x-ray tube along the length of the grid without
loss of primary radiation from grid "cutof

9. CROSSED GRID
• Made of two superimposed linear grids that have
the same focusing distance .
• Grid ratio of two crossed grids is equal to the sum
of the ratio of the two linear grids .
• Cannot be used with oblique techniques requiring
angulation of the Xray tube

11. FOCUSSED GRID
• Grid made up of lead strips that are slightly angled
so that they focus in space .
• May be either linear or crossed because the
focussing refers to cross sectional plane of lead
strips
• Most grids are focused

12. • Linear focused grids converge at a line in space
called CONVERGENT LINE .
• Crossed Grids converge in a point in space called
CONVERGENT POINT .
• FOCAL DISTANCE : Perpendicular distance between
the grid and the convergent line or point .