Performance Evaluation of a miniPET Camera for Brain Scanning

Arif Mahmud¹, Md. Moshiur Rahman²

¹Department of Physics, BGMEA University of Fashion and Technology, Dhaka, Bangladesh.
²Department of Physics, Jahangirnagar University, Dhaka, Bangladesh.

DOI: 10.4236/ijmpcero.2015.41010                

Abstract

A nuclear miniPET camera was constructed with 2 bucket rings, each having 8 BGO detector modules for brain scanning. After calibration of the camera, an experimental investigation of sensitivity was carried out to evaluate the performance of this PET scanner. The characteristics of NECR were examined for comparisons of count rate considering the statistical noise due to scattered and random events. NECR performance was observed using 10 cm diameter phantom filled with 1 L water and 240 MBq of 18F. All data were acquired in 2D acquisition mode but without septa. Randoms were estimated by introducing delay into the coincidence circuit which was an extra 100 ns time delay. Multiples were recorded simultaneously with the prompt and delayed events. The true plus scattered coincidence events were calculated as the difference between prompt and random plus multiple events. After recording all the data, the noise equivalent count rate (NECR) was calculated and graphically presented. It is observed that NEC value is significantly lower than other similar scanners. Comparing the individual components of the count rate, a much higher randoms rate is observed for the camera because of the absence of any side shielding, so that out of field activity contributes significantly to the randoms rate and hence reduces the NECR value.

Keywords

PET, BGO, NECR, Prompt-Events, Detector-Module & Septa

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Das, C., Kumar, R., Balakrishnan, V.B., Chawla, M. and Malhotra, A. (2008) Disseminated Tuberculosis Masquerading as Metastatic Breast Carcinoma on PET-CT. Clinical Nuclear Medicine, 33, 359-361. http://dx.doi.org/10.1097/RLU.0b013e31816a858e
[2]	Parker, D.J. and McNeil, P.A. (1996) Positron Emission Tomography for Process Applications. Measurement Science and Technology, 7, 287-296. http://dx.doi.org/10.1088/0957-0233/7/3/009
[3]	Smith, R.J. and Karp, J.S. (1996) A Practical Method for Randoms Subtractions in Volume Imaging PET from Detector Singles Count Rate Measurements. IEEE Transactions on Nuclear Science, 43, 1981-1987. http://dx.doi.org/10.1109/23.507257
[4]	Humm, J.L., Rosenfeld, A. and Del Guerra, A. (2003) From PET Detectors to PET Scanners. European Journal of Nuclear Medicine and Molecular Imaging, 30, 1574-1597. http://dx.doi.org/10.1007/s00259-003-1266-2
[5]	Jerusalem, G., Hustinx, R., Beguin, Y. and Fillet, G. (2003) PET Scan Imaging in Oncology. European Journal of Cancer, 39, 1525-1534. http://dx.doi.org/10.1016/S0959-8049(03)00374-5
[6]	Bettinardi, V., Danna, M., Savi, A., Lecchi, M., Castiglioni, I., Gilardi, M.C., Bammer, H., Lucignani, G. and Fazio, F. (2004) Performance Evaluation of the New Whole-Body PET/CT Scanner: Discovery ST. European Journal of Nuclear Medicine and Molecular Imaging, 31, 867-881. http://dx.doi.org/10.1007/s00259-003-1444-2
[7]	MacDonald, L.R., Schmitz, R.E., Alessio, A.M., Wollenweber, S.D., Stearns, C.W., Ganin, A., Harrison, R.L., Lewellen, T.K. and Kinahan, P.E. (2008) Measured Count Rate Performance of the Discovery STE PET/CT Scanner in 2D, 3D and Partial Collimation Acquisition Modes. Physics in Medicine and Biology, 53, 3723-3738. http://dx.doi.org/10.1088/0031-9155/53/14/002
[8]	Strother, S.C., Casey, M.E. and Hoffmann, E.J. (1990) Measuring PET Scanner Sensitivity: Relating Count Rates to Image Signal-to-Noise Ratios Using Noise Equivalent Counts. IEEE Transactions on Nuclear Science, 37, 783-788. http://dx.doi.org/10.1109/23.106715
[9]	Schulthess, G.K.V. (2006) Molecular Anatomic Imaging: PET-CT and SPECT-CT Integrating Modality Imaging. 2nd Edition, Lippincott Williams & Wilkins, Philadelphia, Ch. 5, 41.
[10]	Turkington, T.G. (2001) Introduction to PET Instrumentation. Journal of Nuclear Medicine Technology, 29, 4-11.
[11]	Ahasan, M.M. (2009) Design and Initial Performance Absent of a Prototype Large Ring PET Scanner (macroPET). Ph.D. Thesis, The University of Birmingham, Birmingham.
[12]	Ahasan, M.M. (2011) Evaluation of Scatter Fraction (SF) of a 16-Ring Positron Emission Tomography (PET) System. Bangladesh Journal of Medical Physics, 4, 81-86.
[13]	Watanabe, M., Okada, H., Shimizu, K., Ohmura, T., Yoshikawa, E., Kosugi, T., Mori, S. and Yamashita, R. (1996) A High Resolution Animal PET Scanner Using Compact PS-PMT Detectors. International Conference of the IEEE Nuclear Science Symposium, Anaheim, 2-9 November 1996, 1330-1334.