| Title |
Performance assessment of a NaI(Tl) gamma counter for PET applications with methods for improved quantitative accuracy and greater standardization
|
|---|---|
| Published in |
EJNMMI Physics, May 2015
|
| DOI | 10.1186/s40658-015-0114-3 |
| Pubmed ID | |
| Authors |
Martin A Lodge, Daniel P Holt, Paul E Kinahan, Dean F Wong, Richard L Wahl |
| Abstract |
Although NaI(Tl) gamma counters play an important role in many quantitative positron emission tomography (PET) protocols, their calibration for positron-emitting samples has not been standardized across imaging sites. In this study, we characterized the operational range of a gamma counter specifically for positron-emitting radionuclides, and we assessed the role of traceable (68)Ge/(68)Ga sources for standardizing system calibration. A NaI(Tl) gamma counter was characterized with respect to count rate performance, adequacy of detector shielding, system stability, and sample volume effects using positron-emitting radionuclides (409- to 613-keV energy window). System efficiency was measured using (18)F and compared with corresponding data obtained using a long-lived (68)Ge/(68)Ga source that was implicitly traceable to a national standard. One percent count loss was measured at 450 × 10(3) counts per minute. Penetration of the detector shielding by 511-keV photons gave rise to a negligible background count rate. System stability tests showed a coefficient of variation of 0.13% over 100 days. For a sample volume of 4 mL, the efficiencies relative to those at 0.1 mL were 0.96, 0.94, 0.91, 0.78, and 0.72 for (11)C, (18)F, (125)I, (99m)Tc, and (51)Cr, respectively. The efficiency of a traceable (68)Ge/(68)Ga source was 30.1% ± 0.07% and was found to be in close agreement with the efficiency for (18)F after consideration of the different positron fractions. Long-lived (68)Ge/(68)Ga reference sources, implicitly traceable to a national metrology institute, can aid standardization of gamma counter calibration for (18)F. A characteristic feature of positron emitters meant that accurate calibration could be maintained over a wide range of sample volumes by using a narrow energy window centered on the 511-keV peak. |
Mendeley readers
The data shown below were compiled from readership statistics for 40 Mendeley readers of this research output. Click here to see the associated Mendeley record.
Geographical breakdown
| Country | Count | As % |
|---|---|---|
| Unknown | 40 | 100% |
Demographic breakdown
| Readers by professional status | Count | As % |
|---|---|---|
| Researcher | 6 | 15% |
| Student > Ph. D. Student | 5 | 13% |
| Student > Bachelor | 4 | 10% |
| Student > Doctoral Student | 4 | 10% |
| Student > Master | 4 | 10% |
| Other | 7 | 18% |
| Unknown | 10 | 25% |
| Readers by discipline | Count | As % |
|---|---|---|
| Medicine and Dentistry | 9 | 23% |
| Physics and Astronomy | 8 | 20% |
| Engineering | 3 | 8% |
| Pharmacology, Toxicology and Pharmaceutical Science | 2 | 5% |
| Earth and Planetary Sciences | 1 | 3% |
| Other | 3 | 8% |
| Unknown | 14 | 35% |