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

2. 
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





Commissioning of 3D Water Tank
Ion chamber Dosimetry System Effects







Ion Chambers / Electrometers
Film
Metal Oxide Semiconductor Field Effect Transistor (MOSFET)
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

3.  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

4.  Ion
Chambers
 Electrometers
 MOSFET
 Diodes
 Films
 Water tank (?)

5.  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

6.  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

7.  Linearity
 Sensitivity
or nominal response
 Reproducibility
 SSD/Instantaneous dose rate/pulse rate
dependence
 Temperature dependence
 Field size dependence
Missed out on: Angular dependence

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

9.  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

10.  Accuracy
and precision of detector positioning
 Reproducibility

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

12. CPE
failure
RE*
imperfect
CPE
Perfect CPE
• CPE = concept
permanently engraved
• Perfect CPE = inside
the head dissipation of
concept
• Imperfect CPE =
over the head
transmission of
concept
0
1
2
3
4
5
6
7
8
Weekly interactions
* No chargers produced initially, it is all a steady state bliss

13. Thank you very much!