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

Photos of setup

_DSC4718.JPG _DSC4715.JPG _DSC4713.JPG _DSC4716.JPG

(Inside pelicase, outside pelicase, collimators, through pelicase window)

Pre-data Taking Information and Notes

  • Used 200mmx200mmx2mm green scintillator sheet polystyrene base sandwiched by two 200mmx200mmx50mm polystyrene clear plastic blocks
  • 53cm from lens to sheet
  • Check camera in focus with ruler on the sheet
  • Near/Far limit of focus 49.4cm 57.1cm calculated using https://dofmaster.com/dofjs.html
  • Pelicase on couch
  • Scintillator blocks aligned to laser cross hairs
  • 785 mm source to surface distance suitable for output factor/PDD/profile measurements.
  • Room lights out and pelicase window open.
  • Check optical axis aligned with top surface using crosshair in the image analysis.
  • Arrived at hospital at 11am, finished data taking at 5pm

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.


With scintillator sheet
Collimator Size (mm) Monitor Units Image Comments
5 400

calibration_098.JPG

7.5 400

calibration_101.JPG

10 400

calibration_104.JPG

12.5 400

calibration_107.JPG

15 400

calibration_110.JPG

20 400

calibration_113.JPG

25 300

calibration_116.JPG

30 300

calibration_119.JPG

35 250

calibration_122.JPG

40 250

calibration_125.JPG

50 150

calibration_128.JPG

60 150

calibration_095.JPG

No scintillator sheet
Collimator Size (mm) Monitor Units Image Comments
5 400

calibration_166.JPG

7.5 400

calibration_163.JPG

10 400

calibration_160.JPG

12.5 400

calibration_157.JPG

15 400

calibration_153.JPG

20 400

calibration_150.JPG

25 300

calibration_147.JPG

30 300

calibration_144.JPG

35 250

calibration_141.JPG

40 250

calibration_138.JPG

50 150

calibration_135.JPG

60 150

calibration_132.JPG