-  Vibha Chaswal (07-15-2008 – 09/11/2008)

  The resident should gain an understanding of the accuracy and precision of each radiation measurement system, as well as its appropriate application.

  Commissioning of Dose Measurement Systems   Ion Chambers / Electrometers   Film   Metal Oxide Semiconductor Field Effect Transistor (MOSFET)

  Commissioning of 3D Water Tank   Ion chamber Dosimetry System Effects

  Leakage   Stem Effect   Signal-to-noise for different chamber volumes   Variation with bias level and polarity at different dose rates   Variation with changes in water temperature

  Perform dose profile measurements with each detector and compare results.   Manual Film Densitometry

  H&D curve creation (10x10 field size, 6VM x-rays)   depths of 1.5 cm and 10 cm in solid water,   EDR2 film and XV

 Know dosimetric systems  Have a feel for numbers you see in any

dosimetric calculations routinely in the clinic  Learn to design experiments to understand

concepts  Assign applications to dosimeters – which one

for which

  Ion Chambers  Electrometers  MOSFET  Diodes  Films  Water tank (?)

 Linearity  Stem effect  Polarity effect  Angular dependence  Collection Efficiency  Signal to Noise ratio b/w three ion chambers  nC/cc/cGy of cylindrical ion chambers

 SNR b/w three electrometers  Leakage –   cable current (from IC cable alone and from IC

cable and tri-axial cable together)   with and without connecting assembly to ion

chambers

  Linearity   Sensitivity or nominal response   Reproducibility   SSD/Instantaneous dose rate/pulse rate

dependence   Temperature dependence   Field size dependence

Missed out on: Angular dependence

 Linearity  Sensitivity  Fading effect  Dose uncertainty  Entrance and exit doses vs PPC measured dose  Reproducibility

 H and D curve for the XV film  H and D curve of the EDR film  Depth dependence of film  SNR and variance or response along a film,

tested using XV film

 Accuracy and precision of detector positioning  Reproducibility

 Energy dependence  Dose rate dependence  Comparison of profiles and PDD by each  Photons vs Electrons  EDR films and Water tank

0 1 2 3 4 5 6 7 8

Weekly interactions

RE* •  CPE = concept permanently engraved

•  Perfect CPE = inside the head dissipation of concept

•  Imperfect CPE = over the head transmission of concept

CPE failure

Perfect CPE imperfect CPE

* No chargers produced initially, it is all a steady state bliss

Thank you very much!