Radiotherapy/Experimental Runs/2022-07-26

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

Contents

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 Nikon D7000, 20mm lens, f/2.8, 400ISO
  • Used camera control pro 2 app
  • Image of ruler taken at sheet for pixels to mm conversion
  • 5 images taken at each collimator size with 1 background image each.
  • Change exposure time until near max saturation - get's best bit depth
  • View data analysis here

First run

With scintillator sheet
Collimator Size (mm) Exposure (s) Image Comments
5 30

size_5mm.jpg

7.5 20

size_7-5mm.jpg

10 15

size_10mm.jpg

12.5 10

size_12-5mm.jpg

15 8

size_15mm.jpg

20 8

size_20mm.jpg

25 6

size_25mm.jpg

30 6

size_30mm.jpg

35 5

size_35mm.jpg

40 4

size_40mm.jpg

50 3

size_50mm.jpg

60 3

size_60mm.jpg

No scintillator sheet
Collimator Size (mm) Exposure (s) Image Comments
60 3

size_60mm.jpg

Can see green discolouration caused by previous irradiations.
Blocks must have been rotated by 90 when re-assembling

Second run
Replaced plastic blocks from first run with new un-irradiated plastic blocks, but using same green scintillator sheet.
With scintillator sheet
Collimator Size (mm) Exposure (s) Image Comments
5 30

size_5mm.jpg

7.5 20

size_7-5mm.jpg

10 15

size_10mm.jpg

12.5 10

size_12-5mm.jpg

15 8

size_15mm.jpg

20 8

size_20mm.jpg

25 6

size_25mm.jpg

30 6

size_30mm.jpg

35 5

size_35mm.jpg

40 4

size_40mm.jpg

50 3

size_50mm.jpg

60 3

size_60mm.jpg

Green discolouration probably from scintillator sheet.
Rotated by 90 when re-assembling blocks and sheet

No scintillator sheet
Collimator Size (mm) Exposure (s) Image Comments
5 30

size_5mm.jpg

7.5 20

size_7-5mm.jpg

10 15

size_10mm.jpg

12.5 10

size_12-5mm.jpg

15 8

size_15mm.jpg

20 8

size_20mm.jpg

25 6

size_25mm.jpg

30 6

size_30mm.jpg

35 5

size_35mm.jpg

40 4

size_40mm.jpg

50 3

size_50mm.jpg

60 3

size_60mm.jpg

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