1. Non-imaging devices in Nuclear Medicine Pawitra Masa-at 4937092 SIRS/M March 23, 2007

3. Radionuclide dose calibrators

4. Gas-Filled Detectors I ; Ionization chamber region P ; Proportional region GM ; Geigur-Mueller region

6. Ionization Chamber HV + - Negative ion Positive ion 1234 Electrometer The response is proportional to ionization rate (activity, exposure rate)

9. Dose calibrators SC97 Proportionality between the number of photons emitted and the ionization current Well-shaped ionization chamber filled with a gas of high atomic number (e.g. Xenon) and kept under pressure

11. ACTIVITY MEASUREMENT Setting Measured activity Tc-99m 1.00 Co-57 1.19 In-111 2.35 Tl-201 1.76 Ga-67 1.12 I-123 2.19 I-131 1.43 Measured activity/True activity of Tc.99m if the indicated settings are used

12. Geometric efficiency The quotient: number of photons reaching the detector over the number of photons emitted from the sample Increasing geometric efficiency

13. SAMPLE HOLDER (reproducible geometry)

16. Sealed sources for calibration of activity meters 1.9 5.27 y 1173, 1332 Co-60 7.4 30 y 662 Cs-137 9.3 10.7 y 81, 356 Ba-133 185 271 d 122 Co-57 Activity (MBq) Half-life Photon energy (keV) Radionuclide

17. Measurement of precision and accuracy Source (sealed) : Cs-137 or Co-57 Procedure: Select settings for the radionuclide and adjust background. Insert source in holder and make 10 measurements. Data analysis : To assess precision , calculate for each source (i) the percentage difference between the measured activity A i and their mean A mv . (+/-5%) To assess accuracy , calculate the percentage difference between the mean activity and the certified activity. (+/- 10%).

18. Measurement of reproducibility Measure the activity of a sealed reference source e.g. every morning. Use Tc-99m settings.

20. Measurement of linearity Use a radionuclide with short half-life e.g. Tc-99m Make repeated measurements during several half-lives.

25. Examples of use of sample counters RIA 125 I Kidney clearance 51 Cr Vitamin B12 deficiency 57 Co, 58 Co Ferrokinetic studies 59 Fe Total body water 3 H Blood volume 125 I, 51 Cr, 99m Tc Biomedical research 3 H, 14 C

26. Gamma counter HV Ampl. PHA Timer Scaler Rate- meter Gain Base Window Voltage Detector Sample Lead shield PM-tube

27. Scintillation detector Amplifier PHA Scaler Proportionality between the signal and the energy absor- bed in the detector

28. Pulse height analyzer UL LL Time Pulse height (V) The pulse height analyzer allows only pulses of a certain height (energy) to be counted. counted not counted

29. Pulse-height distribution NaI(Tl)

31. Probe system HV Ampl. PHA Timer Scaler Rate- meter Gain Base Window Voltage Recorder Collimator PM D

33. Window setting Energy window setting depends on the energy resolution of the detector and the photon energies

34. Gamma counter Different design of the detector

36. Liquid scintillation counter

39. Liquid scintillation counter PM PM Coinc Ampl PHA Scaler Timer No window 100% geometric efficiency Sample mixed with scintillation solution

41. Thank you Pawitra Masa-at 4937092 SIRS/M March 23, 2007