(W) (1) (b)(i) 3.0 +/- 0.5 (cm) (1) (b)(ii) an explanation this frequency linking RA loses intensity more 2 MHz (1)and  gradually highest any one from: penetration has a higher  accept "2MHz and intensity inside tissue 4MHz" with correct (1) reason for 1 mark less energy  absorbed (1) less attenuation  (1) penetrates  furthest /deepest (1) (2) Indicative Content Mark QWC *(c) A comparison of endoscopes with any one of the following devices: Diagnostic devices CAT scanners  Fluoroscopes  Thermal imagers  / IR thermometers Pulse oximeters  PET scanners  X-ray machines  Gamma  camerasLink to electromagnetic radiation Endoscopes use  TIR of light in optical fibres CAT scanners X-  rays and computer to generate 3D images  Fluoroscopes use X- rays and a video camera Thermal imagers  use infrared emitted by a body IR / red LEDs  used to measure oxygen levels PET scanners  detect radiation emitted by electronpositron annihilation Gamma cameras  detect gamma rays from radioactive sourcesOther factors for (6)
(W) (1) (b)(i) 3.0 +/- 0.5 (cm) (1) (b)(ii) an explanation linking  2 MHz (1)and any one from:  has a higher intensity inside tissue (1)  less energy absorbed (1)  less attenuation (1)  penetrates furthest /deepest (1) this frequency RA loses intensity more gradually highest penetration accept "2MHz and 4MHz" with correct reason for 1 mark (2) Indicative Content Mark QWC *(c) A comparison of endoscopes with any one of the following devices: Diagnostic devices  CAT scanners  Fluoroscopes  Thermal imagers / IR thermometers  Pulse oximeters  PET scanners  X-ray machines  Gamma camerasLink to electromagnetic radiation  Endoscopes use TIR of light in optical fibres  CAT scanners X- rays and computer to generate 3D images  Fluoroscopes use X- rays and a video camera  Thermal imagers use infrared emitted by a body  IR / red LEDs used to measure oxygen levels  PET scanners detect radiation emitted by electronpositron annihilation  Gamma cameras detect gamma rays from radioactive sourcesOther factors for (6)