6. Main features of X-ray tube

23. Suppose a section consists of four voxels with intensities as below. The number on each voxel is the pixel intensity that is to be reproduced

24. If a beam of X-rays is directed from the left, then detectors will give readings of 5 and 9 This allows the four voxels to be reconstructed

25. The X-ray tube and detectors are now rotated through 45 o

26. The procedure is repeated and the X-ray tube and detectors rotated a further 45 o

27. Final images are taken after rotating a further 45 o

41. Some approximate values of specific acoustic impedance Z

45. Values for ultrasound of frequency 1MHz

47. Example of A-scan