The document discusses x-ray grids, which are devices placed between the patient and film/detector to reduce scattered radiation reaching the film. Grids are made of thin lead strips separated by interspacing material like carbon or aluminum. They work by absorbing most scattered radiation, which travels obliquely to the lead strips, while allowing primary rays to pass through the interspaces. This increases image contrast. Grids are characterized by their ratio, frequency, contrast improvement factor, and type of movement (parallel, focused, moving). Moving grids are commonly used as they provide the benefits of a fine grid without visible grid lines.

1. X-RAY GRID
/BUCKY
REFERRED BY:
THAYALAN SIR
-BOOK AND
CHRISTENSEN’S BOOK

2. GRID
 GRID IS A DEVICE WHICH REDUCES THE AMOUNT OF SACTTERED
RADIATION REACHING THE FILM.
 THE GRID IS PLACED IN BETWEEN PATIENT AND THE FILM/DETECTOR
CONSTRUCTION OF GRID:
 GRID ARE MADE UP OF THIN LEAD STRIPS SEPERATED BY INTERSPACING MATERIAL.
 THE INTERSPACING MATERIAL IS USUALLY MADE UP OF ORGANIC
COMPOUND (CARBON BASEED).
 OR ALUMINIUM WHICH HAS LOW ATOMIC NUMBER.
 THIS WHOLE THING IS COVERED BY ALUMINIUM
ENVELOPE.

3. FUNCTION OR WORKING OF GRID:
THE WORKING OF GRID US EXPLAINED BY THE FIGURE
1. MOST OF THE PRIMARY RAY , LIKE RAY1,PASS THROUGH THE INTERSPACING MATERIAL
TO REACH FILM TO PRODUCE IMAGE
2.MOST OF THE SCATTERED RADIATION LIKE RAY 2 TRAVEL OBLIQUELY TO THE LEAD STRIP
AND ABSORBED BY THE LEAD STRIP
3.SOME OF THE PRIMARY RAY LIKE RAY 3 ARE ABSORED BY THE LEAD STRIP TO PRODUCE
WHITE LINE IN THE IMAGE BUT , THESE WHITE LINES ARE NOT SEEN BECAUSE THE LEAD
STRIP ARE SO THIN AND CLOSE TO EACH OTHER
4. SOME OH THE SCATTERED RAY LIKE RAY 4 WITH THIS SMALL ANGLE OF SCATTER ARE
PAREALLEL TO THE LEAD STRIP ARE NOT ABSORBED BY THE LEAD STRIP . THEY PASS
THROUGH THE INTERSPACING MATERIAL TO REACH THE FILM

4.  BUT THE GRID CUT OFF 80 TO 90 % OF SCATTERED RADIATION REACHING THE FILM
AND THERE BY INCREASES THE CONTRAST OF THE IMAGE
GRID CHARACTERISTICS:
SOME OF THE IMPORTANT CHARACTERISTICS OF THE GRID ARE DISCUSED BELOW;
1.GRID RATIO:
 GRID RATIO IS THE RATIO OF THE HEIGHT OF THE INTERSPACING MATERIAL TO
ITS WIDTH BETWEEN TWO LEAD STRIPS
GRID RATIO = h/d
AS GRID RATIO INCREASES , THE GRID REMOVES MORE SCATTERED RADIATION, THE
TYPICAL GRID RATIO RANGES FROM 4:1 TO 16:1

5. 2. GRID FREQUENCY:
 IT IS DIFINED AS THE NUMBER OF LEAD LINES PER cm OR inch.
 THE GRID FREQUENCY RANGES FROM 25 TO 60 LEAD LINES PER cm
 IF THERE ARE MORE LEAD LINES , IT IS CALLED FINE GRID
 IF THERE ARE LESS LEAD LINES , IT IS CALLED COARSE GRID
3.CONTRAST IMPROVEMENT FACTOR:
 IF THE GRID IS USED THE CONTRAST IS IMPROVED .
 CIF IS DEFINED AS THE RATIO OF IMAGE CONTRAST WITH GRID TO IMAGE
CONTRAST WITHOUT GRID
CIF= IMAGE CONTRAST WITH GRID
IMAGE CONTRAST WITHOUT GRID
4. GRID FACTOR OR BUCKY FACTOR:
 GRID FACTOR IS DEFINED AS THE RATIO OF X-RAY EXPOSURE WITH GRID T
X-RAY EXPOSURE WITHOUT GRID

6. GRID FACTOR = X-RAY EXPOSURE WITH GRID
X-RAY EXPOSURE WITHOUT GRID
TYPES OF GRID:
THERE ARE DIFFERENT TYPES OF GRID USED IN RADIOLOGY .
THEY ARE:
1. PARALLEL GRID
2. FOCUSSED GRID
3. PSUDOFOCUSSED GRID STATIONARY GRID
4. CROSSED GRID
5. MOVING GRID (BUCKY)
PARALLEL GRID:
 IN PARALLEL GRID , THE LEAD STRIPS ARE PARALLEL TO EACH OTHER
 IT IS EASY TO MANUFACTURE BUT IT PRODUCE GRID CUT OFF
 SINCE X-RAY BEAM IS DIVERGENT , THE PRIMARY X-RAY OF THE EDGES
TRAVEL OBLIQUELY TO YHE LEAD STRIP
 AND ARE ABSOBED BY THE LEAD STRIP THIS IS CALLED “GRID CUT OFF”

7.  WHEN THE GRID RATIO INCREASES , GRID CUT OFF INCREASES
FOCUSSED GRID:
 IN FOCUSSEDD GRID , THE LEAD STRIP ARE ARRANGED SUCH THAT , THEY FOCUS AT
PARTICULAR DIATANCE
 THIS DESIGN IS TO AVOID GRID CUT OFF
 THE FOCUS GRID DESIGNED FOR PARTICULAR FOCUS CAN BE USED FOR A RANGE OF
FOCUS
 IF FFD (FILM TO FOCUS DISTANCE) IS MORE THAN THE RANGE , THEN THERE WILL BE
GRID CUT OFF
 IN FOCUS GRID THE CENTRAL AXIS OF X-RAY , SHOULD PASS THROUGH THE CENTRE OF
THE GRID
 THE DISADVENTAGE OF FOCUSSED GRID IS, IT IS DIFFICULT TO MANUFACTURE

8. PSEUDOFOCUSSED GRID:
 IN THIS , THE THICKNESS OF THE LEAD STIP DECREASES FROM CENTRE TO EDGE
 THIS DESIGN IS TO PREVENT GRID CUT OFF AT THE EDGES
 BUT THE CONTRAST IMPROVEMENT WILL BE HIGHER IN THE CENTER AND REDUCES
FROM CENTER TO EDGE
CROSSED GRID:
 THE SCATTERED X-RAY BEAM TRAVELLING PARALLEL TO THE LEAD STRIP WILL NOT
BE ABSORBED BY PARALLEL GRID OR FOCAL GRID
 IN ORDER TO ABSORB THIS SCATTERED RADIATION , CROSSED GRIF ARE USED
 CROSSED GRID IS TWO PARALLEL GRID PLACED ONE THE OTHER SO THAT , THE LEAD
STRIP ARE PERPENDICULAR TO EACH OTHER (CROSSED)
 IT EFFECTIVELY ABSOR SCATTERED X-RAY IN ANY DIRECTION.
 THE DISADVANTAGE OF CEOSSED GRID IS , THE X-RAY BEAM SHOULD FALL
PERPENDICULAR TO THE GRID AND IF THE BEAM IS ANGULATED , IT WILL ABSORB
THE PRIMARY BEAM

9. MOVING GRID (POTTER – BUCKY):
 THE DESIGN OF STATIONARY FINE GRID IS DIFFICULT TO MANUFACTURE
 SO INSTEAD OF FINE , COARSE GRID IS USED
 IN COARSE GRID THE LEAD STRIP ARE THICK AND ARE SEPERATED BY LARGE DIATANCE
 BUT , IF THE COARESE GRID IS USED , THE GRID LINES ARE SEEN IN THE RADIOGRAPH
 HENCE , THE COARE GRID IS MOVED PERPENDICULAR TO THE LEAD STRIP TO AND
DUEING X-RAY EXPOSURE
 THE MOVING COARSE GRID IS EQUIVALENT TO FINE GRID
 GENERALLY , THE BUCKY IS PLACED BETWEEN PATIENT AND THE FILM
 THE GRID SHOULD MOVE AT LEAST 2-3 Cm ON EITHER SIDE
 THE SPEED OF GRID MOVEMENT IS SUCH THAT , IT BLURS THE GRID LINE IN
THE RADIOGRAPH
 GENERALLY , THE GRID STARTS TO MOVE , WHEN THE STAND BY SWITCH IS PRESSED
BEFORE EXPOSURE AND GRID MOVEMENT SHOULD BE STOPPED AFTER THE EXPOSURE
IS OVER
 THERE ARE 3 TYPES OF GRID MOVEMENT:
i. SINGLE STROKE MOVEMENT
ii. OSCILLATING MOVEMENT
iii. RECIPROCATING MOVEMENT

10. SINGLE STROKE MOVEMENT:
 IN THIS , THE GRID IS ATTACHED TO THE WOUND SPRING
 BEFORE EXPOSURE , THE WOUND SPRING IS TIGHTENED SO THAT THE GRID
MOVES WITH A SPRING ACTION
 THE SPEED OF GRID MOVEMENT DECREASES WITH TIME
 THE EXPOSURE SHOULD STOP , BEFORE THE GRID MOVEMENT STOP.
OSCILLATING MOVEMENT:
 IN THIS , THE GRID IS PLACED IN BETWEEN 2 PAIR OF ELECTROMAGNETES
 THE ELECTROMAGANETS 1 AND 2 ARE ACTIVATED ALTERNATIVELY BY APPLYING
THE CURRENT TO THE MAGNETS 1 AND 2 ALTERNATIVELY
 THE GRID OSCILLATE IN BETWEEN THE ELECTROMAGANET
 THE SPEED OF GRID MOVEMENT IS AS SHOWN IN FIGURE

11. RECIPROCATING MOVEMENT:
 IN THIS , THE SPEED OF GRID MOVEMENT IS FAST IN ONE DIRECTION AND RETURNS
SLOWLY IN OTHER DIRECTION
 THE SPEED OF GRID MOVEMENT IS AS SHOWN IN FIGURE

12. THE END
REFERRED BY:
THAYALAN SIR
-BOOK AND
CHRISTENSEN’S BOOK