1. RADIOGRAPHIC GRIDS

2. INVENTED BY DR. GUSTAV BUCKY
GRIDS
INVENTED BY DR. GUSTAV BUCKY

3. GRIDS
DEVICES THAT REDUCE THE AMOUNT OF SCATTERED RADIATION REACHING THE IMAGE RECEPTOR

4. GRIDS DO NOT REDUCE THE AMOUNT OF SCATTER RADIATION REACHING THE IMAGING PERSONNEL

5. GRIDS DO INCREASE RADIATION EXPOSURE OF PATIENTS

6. FACTORS AFFECTING SCATTER PRODUCTION WITHIN THE PATIENT
KILOVOLTAGE
BEAM SIZE
THICKNESS OF IRRADIATED TISSUE
COMPOSITION OF IRRADIATED TISSUE
Z# OF IRRADIATED TISSUE

7. GRIDS STRIPS ARE MADE OF LEAD (Pb)
LEAD HAS Z#
AND ABSORBS SCATTER RADIATION THROUGH ______ INTERACTION
PHOTOELECTRIC

8. LEAD

9. GRIDS CONS HIGHER PATIENT DOSE PROS HIGHER CONTRAST
INCREASED VISIBILITY OF DETAIL (CONTRAST RESOLUTION)

10. GRID RADIOGRAPHY IS RECOMMENDED FOR:
ANATOMICAL PARTS > 10 cm
WITH HIGH kVp ( NOT ALWAYS—MAMMO)
SOFT TSSUE STRUCTURES TO INCREASE CONTRAST
STRUCTURES AFFECTED BY PATHOLOGICAL CONDITION THAT WOULD INCRESE SCATTER PRODUCTION

11. SCATTER RADIATION-PRODUCED WITHIN THE PATIENT THROUGH _______INTERATION
CAMPTON

13. -- -- --

14. SCATTER
TUBE

15. SCATTER
SCATTER

16. GRID CONSTRUCTION

17. GRID RATIO G.R.= H/D

18. GRID SURFACE X-RAY ABSORPTION—TYPICAL GRID STRIPS-50 MICROMETERS INTERSPACE –350 MICROMETERS
X-RAY ABSORPTION (%)= WIDTH OF STRIPS X 100
WIDTH OF STRIPS + WIDTH OF INTERSPACE

19. HIGH QUALITY GRIDS CAN ATTENUATE 80%-90% OF SCATTER RADIATION

20. GRID RATIO VS CLEANUP
RATIO
SCATTER CLEAN-UP

21. BUCKY FACTOR BF=I.R./T.R.

22. NEW MAS= ORIGINAL MAS X NEW GRID FACTOR/OLD FACTOR
GRID CONVERSIONS
NO GRID
5:1
8:1
12:1
16:1
1 X MAS , KVP X 1
2 X MAS , KVP
4 X MAS , KVP
5 X MAS , KVP
6 X MAS , KVP
NEW MAS= ORIGINAL MAS X NEW GRID FACTOR/OLD FACTOR

23. GRID FREQUENCY # OF LEAD STRIPS PER INCH OR CM
G.F.= 10,000 MICROMETERS/CM
T + D MICROMETER/LINE PAIR
T-STRIP WIDTH
D-INTERSPACE WIDTH

24. GRID TYPES STATIONARY MOVING-SINGLE STROKE & RECIPROCATING LINEAR
CROSSHATCH
FOCUSED

25. MOVING GRID DR. HOLLIS POTTER MODIFIED BUCKY DIAPHGRAM POTTER-BUCKY DIAPHGRAM

26. P-B DIAPHRAGM

27. GRIDS:

28. TILTING OF THE LEAD STRIPS TO CREATE FOCUSED GRID
CANTING
TILTING OF THE LEAD STRIPS TO CREATE FOCUSED GRID

29. FOCUSED GRID

30. CROSSHATCH GRID

31. LINEAR GRID

32. LINEAR GRID USED IN TOMOGRAPHY

33. BIGGEST DISADVANTAGE OF LINEAR & CROSS GRID
GRID CUT-OFF

34. GRID CUT-OFF

35. FOCUSED GRID

36. GRIDS

37. GRIDS

38. GRID INFO

39. GRID EFFICIENCY
CIF GS

40. CONTRAST IMPROVEMENT FACTOR
CIF= CONTRAST WITH GRID/CONTRAST WITHOUT GRID

41. GS=NONSCATTER TRANSMITTED/SCATTER TRANSMITTED
GRID SELECTIVITY
GS=NONSCATTER TRANSMITTED/SCATTER TRANSMITTED

42. GRID ERRORS OFF LEVEL OFF CENTER OFF FOCUS UPSIDE DOWN
OFF FOCUS & OFF CENTER
CUTOOF ACROSS ENTIRE IMAGE, LIGHT IMAGE
CUTOFF TOWARD THE EDGE OF THE IMAGE
SEVERE CUTOFF TOWARD THE EDGE OF THE IMAGE
DARK ON ONE SIDE & LIGHT ON THE OTHER

43. GRID ERRORS

44. GRID ERRORS

45. OFF FOCUS

46. UPSIDE DOWN

47. GRID ARTIFACTS
MOIRE EFFECT
STROBOSCOPIC EFFECT
DAMAGED GRID

48. MOIRE EFFECT-PLACING GRID IN BUCKY MECHANISM

49. STROBOSCOPIC EFFECT (MOVING GRIDS) -MOTION OF THE GRID IS FROZEN
WHEN USING SHORT EXPOSURE TIME ( SHORTER THAN MOVEMENT OF THE GRID)
RECIPROCATING MECHANISM IS BROKEN

50. AIR GAP TECHNIQUE