Radiotherapy/Experimental Runs/2020-02-04

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Second experimental measurements with Cyberknife at Birmingham. Green scintillator thin sheet measurements only.

Setup

Schematic

setup.png

Pre-data Taking Information and Notes

  • Phantom
    • 200mmx200mmx2mm blue scintillator sheet polystyrene base
    • sandwiched by two 200mmx200mmx50mm polystyrene clear plastic blocks
  • 565mm from lens to sheet
  • Check camera in focus with ruler on the sheet
  • Ruler in focus at sheet
  • Scintillator blocks aligned to laser cross hairs
  • 785 mm source to surface distance suitable for output factor/PDD/profile measurements.
  • Wooden box is covered with black cloth
  • Camera height adjusted with wooden plates
  • Top surfaces of plastic blocks and sheet aligned with paper underneath

Data Taking

  • All images taken with
    • Canon EOS 1100D
    • 18-55mm lens
    • f/5
    • 200ISO
    • 30s exposure
  • Beam turned on for a given amount of time within the 30s exposure
  • This is noted in monitor units, with the beam having constant 1000MU/minute
  • Used EOS utility app for controlling camera
  • Image of ruler taken at sheet for pixels to mm conversion
  • 3 images taken at each collimator size with 1 background image each.


Collimator Size (mm) Monitor Units With sheet No sheet
5 400

calibration_098.JPG

calibration_166.JPG

7.5 400

calibration_101.JPG

calibration_163.JPG

10 400

calibration_104.JPG

calibration_160.JPG

12.5 400

calibration_107.JPG

calibration_157.JPG

15 400

calibration_110.JPG

calibration_153.JPG

20 400

calibration_113.JPG

calibration_150.JPG

25 300

calibration_116.JPG

calibration_147.JPG

30 300

calibration_119.JPG

calibration_144.JPG

35 250

calibration_122.JPG

calibration_141.JPG

40 250

calibration_125.JPG

calibration_138.JPG

50 150

calibration_128.JPG

calibration_135.JPG

60 150

calibration_095.JPG

calibration_132.JPG

Before and after irradiation

5mm_010.JPG calibration_092.JPG

Green discolouration observed after irradiation. Only present when the lights are on