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1.  Targeted gold nanoparticles enable molecular CT imaging of head and neck cancer: an in vivo study

Sara Khademi, Saeed Sarkar, Ali Shakeri-Zadeh, Neda Attaran, Sharmin Kharrazi, Mohammad Reza Ay, Hosein Azimian, Hossein Ghadiri
Peer-reviewed Journal Publication
The international journal of biochemistry & cell biology,2018,Vol 114

2.  Sparse-view statistical image reconstruction with improved total variation regularization for X-ray micro-CT imaging

G Mahmoudi, MR Fouladi, MR Ay, A Rahmim, H Ghadiri
Peer-reviewed Journal Publication
Journal of Instrumentation, 2019, Vol 14

3.  NEMA NU‐4 2008 Performance Evaluation of Xtrim‐PET: A prototype Si PM‐based preclinical scanner

Mahsa Amirrashedi, Saeed Sarkar, Pardis Ghafarian, Reza Hashemi Shahraki, Parham Geramifar, Habib Zaidi, Mohammad Reza Ay
Peer-reviewed Journal Publication
Medical physics,2019

4.  A novel approach to automatic position calibration for pixelated crystals in gamma imaging

Salar Sajedi, Navid Zeraatkar, Sanaz Kaviani, Hadi Khanmohammadi, Saeed Sarkar, Hamid Sabet, Mohammad Reza Ay
Peer-reviewed Journal Publication
Iranian Journal of Nuclear Medicine,2019,Vol 27

5.  Dual-energy CT imaging of nasopharyngeal cancer cells using multifunctional gold nanoparticles

Hossein Ghadiri, Sara Khademi, Saeed Sarkar, Ali Shakeri-zadeh, Neda Attaran, Mohammad Reza Ay, Hosein Azimian, Razieh Solgi
Peer-reviewed Journal Publication
IET Nanobiotechnology, 2019

6.  The influence of misregistration between CT and SPECT images on the accuracy of CT-based attenuation correction of cardiac SPECT/CT imaging: Phantom and clinical studies

Leila Saleki, Pardis Ghafarian, Ahmad Bitarafan-Rajabi, Nahid Yaghoobi, Babak Fallahi, Mohammad Reza Ay
Peer-reviewed Journal Publication
Iranian Journal of Nuclear Medicine,2019,Vol 27,pp63-72

7.  Validation and evaluation of a GATE model for MAMMI PET scanner

Azadeh Emami, Pardis Ghafarian, Hossien Ghadiri, Parham Geramifar, Mohammad Reza Ay
Peer-reviewed Journal Publication
Iranian Journal of Nuclear Medicine,2019

8.  A Novel Method for Measuring the MTF of CT Scanners: A Phantom Study

Hamidreza Khodajou-Chokami, Seyed Abolfazl Hosseini, Mohammad Reza Ay, Ali Safarzadehamiri, Pardis Ghafarian, Habib Zaidi
Proceeding and Conference Record
2019 IEEE International Symposium on Medical Measurements and Applications

9.  MCNP-FBSM: Development of MCNP/MCNPX Source Model for Simulation of Multi-Slice Fan-Beam X-Ray CT Scanners

Hamidreza Khodajou-Chokami, Seyed Abolfazl Hosseini, Mohammad Reza Ay, Habib Zaidi
Proceeding and Conference Record
2019 IEEE International Symposium on Medical Measurements and Applications

10.  Direct attenuation correction of brain PET images using only emission data via a deep convolutional encoder-decoder (Deep-DAC)

Isaac Shiri, Pardis Ghafarian, Parham Geramifar, Kevin Ho-Yin Leung, Mostafa Ghelichoghli, Mehrdad Oveisi, Arman Rahmim, Mohammad Reza Ay
Peer-reviewed Journal Publication
European radiology,2019,pp1-3

11.  Development and preliminary results of Xtrim-PET, a modular cost-effective preclinical scanner

Salar Sajedi, Navid Zeraatkar, Mohsen Taheri, Sanaz Kaviani, Hadi Khanmohammadi, Saeed Sarkar, Hamid Sabet, Mohammad Reza Ay
Peer-reviewed Journal Publication
2019, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

12.  Deep-Fill: Deep Learning Based Sinogram Domain Gap Filling in Positron Emission Tomography

Isaac Shiri, Peyman Sheikhzadeh, Mohammad Reza Ay
Peer-reviewed Journal Publication
arXiv preprint arXiv:1906.07168

13.  Design, optimization and performance evaluation of BM-PET: A simulation study

Peyman Sheikhzadeh, Hamid Sabet, Hossein Ghadiri, Parham Geramifar, Pardis Ghafarian, Mohammad Reza Ay
Peer-reviewed Journal Publication
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

14.  PSFNET: ultrafast generation of PSF-modelled-like PET images using deep convolutional neural network

Isaac Shiri, Kevin Leung, Parham Geramifar, Pardis Ghafarian, Mehrdad Oveisi, Mohammad Reza Ay, Arman Rahmim
Peer-reviewed Journal Publication
Journal of Nuclear Medicine,2019,vol 60,pp 1369-1369

15.  HiResPET: high resolution PET image generation using deep convolution encoder decoder network

Isaac Shiri, Kevin Leung, Pardis Ghafarian, Parham Geramifar, Mehrdad Oveisi, Mohammad Reza Ay, Arman Rahmim
Peer-reviewed Journal Publication
Journal of Nuclear Medicine,2019,vol 60,pp 1368-1368

16.  Simultaneous Attenuation Correction and Reconstruction of PET Images Using Deep Convolutional Encoder Decoder Networks from Emission Data

Isaac Shiri, Kevin Leung, Pardis Ghafarian, Parham Geramifar, Mehrdad Oveisi, Mohammad Reza Ay, Arman Rahmim
Peer-reviewed Journal Publication
Journal of Nuclear Medicine,2019,vol 60

17.  Impact of image reconstruction methods on quantitative accuracy and variability of FDG-PET volumetric and textural measures in solid tumors

Ali Ketabi, Pardis Ghafarian, Mohammad Amin Mosleh-Shirazi, Seyed Rabi Mahdavi, Arman Rahmim, Mohammad Reza Ay
Peer-reviewed Journal Publication
European radiology,2019,vol 29,pp 2146-2156

18.  Design and performance evaluation of high resolution small animal PET scanner based on monolithic crystal: a simulation study

A Sanaat, MS Zafarghandi, MR Ay
Peer-reviewed Journal Publication
Journal of Instrumentation,2019, Vol 14

19.  A full quantitative analysis of 18 MV photon beam from 2100 C/D-Varian clinical linear accelerator with and without flattening filter

SR Mahdavi, MR Ay, M Zabihzadeh, M Allahverdi, M Shahriari, M Hoseini-Ghahfarokhi
Peer-reviewed Journal Publication
International Journal of Radiation Research, 2019, Vol 17, P 137-146

20.  Design and performance evaluation of spheroid geometry for brain PET scanner using Monte Carlo modeling

Peyman Sheikhzadeh, Hossein Ghadiri, Parham Geramifar, Pardis Ghafarian, Mohammad Reza Ay
Peer-reviewed Journal Publication
Iranian Journal of Nuclear Medicine, 2019, Vol 27, P 32-37

21.  Monte Carlo-based optimization of a gamma probe system for sentinel lymph node mapping

Azadeh Nikoogoftar, Mojtaba Shamsaie, Navid Zeraatkar, Mohammad Reza Ay
Peer-reviewed Journal Publication
Iranian Journal of Nuclear Medicine,2019, Vol 27, p 8-14

22.  Advantages and disadvantages of removed flattening filter Linac: A Monte Carlo study on full quantitative dosimetric data of 18 MV-Varian Linac

Mansour Zabihzadeh, Seyed Rabee Mahdavi, Mohammad Reza Ay, Mojtaba Hoseini-Ghahfarokhi
Peer-reviewed Journal Publication
Iranian Journal of Medical Physics, 2018, Vol 15, P 446

23.  Conventional Voxel in Tomographic Reconstruction Based upon Plane-Integral Projections–Use It or Lose It?

Hojjat Mahani, Gholamreza Raisali, Alireza Kamali-Asl, Mohammad Reza Ay
Peer-reviewed Journal Publication
Iranian Journal of Medical Physics, 2018, Vol 15, P 269-269

24.  Conventional Voxel in Tomographic Reconstruction Based upon Plane-Integral Projections–Use It or Lose It?

Hojjat Mahani, Gholamreza Raisali, Alireza Kamali-Asl, Mohammad Reza Ay
Proceeding and Conference Record
Iranian Journal of Medical Physics,2018, V ol 15, P 261

25.  Evaluation of effect of gold nanorods and spherical gold nanoparticles of different sizes on X-ray attenuation in computed tomography

Sara Khademi, Hossein Ghadiri, Saeed Sarkar, Sharmin Kharrazi, Seyed Mohammad Amini, Ali Shakeri-Zadeh, Mohammad Reza Ay
Peer-reviewed Journal Publication
Iranian Journal of Medical Physics,2018, Vol 15, P 354

26.  Evaluation of multifunctional targeted gold nanoparticles on X-ray attenuation in nasopharyngeal cancer cells by X-ray imaging

Sara Khademi, Hossein Ghadiri, Saeed Sarkar, Ali Shakerizadeh, Neda Attaran, Sharmin Kharrazi, Mohammad Reza Ay
Peer-reviewed Journal Publication
Iranian Journal of Medical Physics, 2018, Vol 15, P 351

27.  Fast System Matrix Calculation in CT Iterative Reconstruction

Golshan Mahmoudi, Mohammad Reza Ay, Hossein Ghadiri
Peer-reviewed Journal Publication
Iranian Journal of Medical Physics, 2018, Vol 15, P 150-150

28.  Recovery of missing data in partial geometry PET scanners: Compensation in projection space vs image space

Seyedehsamaneh Shojaeilangari, C Ross Schmidtlein, Arman Rahmim, Mohammad Reza Ay
Peer-reviewed Journal Publication
Medical physics, 2018, Vol 45, P5437-5449

29.  Techniques for generating attenuation map using cardiac SPECT emission data only: a systematic review

Getu Ferenji Tadesse, Parham Geramifar, Eyachew Misganew Tegaw, Mohammad Reza Ay
Peer-reviewed Journal Publication
Annals of Nuclear Medicine,2018,p 1-13

30.  Impact of image reconstruction methods on quantitative accuracy and variability of FDG-PET volumetric and textural measures in solid tumors

Ali Ketabi, Pardis Ghafarian, Mohammad Amin Mosleh-Shirazi, Seyed Rabi Mahdavi, Arman Rahmim, Mohammad Reza Ay
Peer-reviewed Journal Publication
European radiology,2018,pp1-11

31.  F-18-PSMA vs. Ga-68-PSMA11; S-value Estimation in XCAT BMIs Using GATE Monte Carlo Code

M Fallahpoor, N Vahidfar, G Divband, F Kalantari, M Ay
Proceeding and Conference Record
EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING,2018, Vol 45,P S737-S737

32.  Monte Carlo simulation of MAMMI PET system and performance evaluation using GATE toolkit

A Emami, H Ghadiri, P Ghafarian, P Geramifar, M Ay
Proceeding and Conference Record
EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING,2018, Vol 45, P S714-S714

33.  Uncertainties in effective dose estimation for CT transmission scan in total body PET-CT imaging with Auto mA3D tube current modulation

Y Salimi, MR Deevband, P Ghafarian, MR Ay
Peer-reviewed Journal Publication
International Journal of Radiation Research, Vol 16, p 465-472

34.  Folic acid-cysteamine modified gold nanoparticle as a nanoprobe for targeted computed tomography imaging of cancer cells

Sara Khademi, Saeed Sarkar, Ali Shakeri-Zadeh, Neda Attaran, Sharmin Kharrazi, Mohammad Reza Ay, Hossein Ghadiri
Peer-reviewed Journal Publication
Materials Science and Engineering: C,2018 ,Vol.89

35.  Reconstruction/segmentation of attenuation map in TOF-PET based on mixture models

Hamidreza Hemmati, Alireza Kamali-Asl, Pardis Ghafarian, Mohammad Reza Ay
Peer-reviewed Journal Publication
Annals of nuclear medicine, 2018, Vol.26, pp 1-11

36.  Capturing Bone Signal in MRI of Pelvis, as a Large FOV Region, Using TWIST Sequence and Generating a 5-Class Attenuation Map for Prostate PET/MRI Imaging

Mehdi Shirin Shandiz, Hamid Saligheh Rad, Pardis Ghafarian, Khadijeh Yaghoubi, Mohammad Reza Ay
Peer-reviewed Journal Publication
Molecular imaging, 2018, Vol 17

37.  Concept design and Monte Carlo performance evaluation of HeadphonePET: a novel brain-dedicated PET system based on partial cylindrical detectors

P Sheikhzadeh, H Sabet, H Ghadiri, P Geramifar, P Ghafarian, MR Ay
Peer-reviewed Journal Publication
Journal of Instrumentation, 2018, Vol 13 ,P07008

38.  An alternative mathematical modeling of the scintillation camera and framework for performance analysis of gamma-ray positioning algorithms

Behnoosh Teimourian Fard, Mojtaba Shamsaei Zafarghandi, Soheil Hosseini, Hamid Sabet, Mohammad Reza Ay
Peer-reviewed Journal Publication
Iranian Journal of Nuclear Medicine, 2018, v.26, P.112-126

39.  The influence of using different reconstruction algorithms on sensitivity of quantitative 18F-FDG-PET volumetric measures to background activity variation

Ali Ketabi, Pardis Ghafarian, Mohammad Amin Mosleh-Shirazi, Seyed Rabi Mahdavi, Mohammad Reza Ay
Peer-reviewed Journal Publication
Iranian Journal of Nuclear Medicine, 2018, Vol.26, pp 87-97

40.  Mixture model based joint-MAP reconstruction of attenuation and activity maps in TOF-PET

H Hemmati, A Kamali-Asl, P Ghafarian, MR Ay
Peer-reviewed Journal Publication
Journal of Instrumentation, 2018, Vol.13

41.  Cardiac contraction motion compensation in gated myocardial perfusion SPECT: A comparative studyRobotic system for SPECT imaging

Narges Salehi, Arman Rahmim, Emad Fatemizadeh, Afshin Akbarzadeh, Mohammad Hossein Farahani, Saeed Farzanefar, Mohammad Reza Ay
Peer-reviewed Journal Publication
Physica Medica, 2018, Vol.49, pp 77-82

42.  Generic high resolution PET detector block using 12× 12 SiPM array

Salar Sajedi, Navid Zeraatkar, Mohsen Taheri, Sanaz Kaviani, Hadi Khanmohammadi, Saeed Sarkar, Hamid Sabet, Mohammad Reza Ay
Peer-reviewed Journal Publication
Biomedical Physics & Engineering Express, 2018, Vol 4

43.  A novel dual energy method for enhanced quantitative computed tomography

A Emami, H Ghadiri, A Rahmim, MR Ay
Peer-reviewed Journal Publication
Journal of Instrumentation, 2018, Vol.13

44.  Evaluation of size, morphology, concentration, and surface effect of gold nanoparticles on X-ray attenuation in computed tomography

Sara Khademi, Saeed Sarkar, Sharmin Kharrazi, Seyed Mohammad Amini, Ali Shakeri-Zadeh, Mohammad Reza Ay, Hossein Ghadiri
Peer-reviewed Journal Publication
Physica Medica, 2018, Vol 45,pp 127-133

45.  Evaluating the Impact of Various Parameters on the Gamma Index Values of 2D Diode Array in IMRT Verification

Keyvan Jabbari, Fakhereh Pashaei, Mohammad R Ay, Alireza Amouheidari, Mohammad B Tavakoli
Peer-reviewed Journal Publication
Journal of medical signals and sensors, Vol 8 , P31-38

46.  Is correction for metallic artefacts mandatory in cardiac SPECT/CT imaging in the presence of pacemaker and implantable cardioverter defibrillator leads?

Zahra Etemadi, Pardis Ghafarian, Ahmad Bitarafan-Rajabi, Hadi Malek, Mohammad Reza Ay
Peer-reviewed Journal Publication
Iranian Journal of Nuclear Medicine, 2018, Vol 26, P 35-46

47.  Resolution Recovery with Pre-Reconstruction Fourier Transforms Filtering for a High Resolution Animal SPECT System

Reza Hashemi Shahraki, Isaac Shiri, Parham Geramifar, Afshin Akbarzadeh, Amir Hossein Sanaat, Mohammad Reza Ay
Peer-reviewed Journal Publication
Frontiers in Biomedical Technologies, 2018, Vol 5,P 74-80

48.  Quantification and Reduction of Respiratory Induced Artifact in Attenuation Correction of PET Data using Respiration Averaged CT: A Simulation and Phantom Study

Fatemeh Sadat Fatemi Nasrollahi, Pardis Ghafarian, Parham Grramifar, Mohammad Reza Ay
Peer-reviewed Journal Publication
Frontiers in Biomedical Technologies, 2017, Vol 3, pp 49-59

49.  Quantification and reduction of respiratory induced artifacts in positron emission tomography/computed tomography using the time-of-flight technique

Roya Sharifpour, Pardis Ghafarian, Arman Rahmim, Mohammad R Ay
Peer-reviewed Journal Publication
Nuclear medicine communications

50.  A Generic, Scalable, and Cost-Effective Detector Front-End Block for PET

Salar Sajedi, Navid Zeraatkar, Mohsen Taheri, Sanaz Kaviani, Hadi Khanmohammadi, Saeed Sarkar, Hamid Sabet, MR Ay
Proceeding and Conference Record
2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), P 1-3

51.  Development of a Preclinical PET System Based on Pixelated LYSO Crystals and SiPM Arrays

Navid Zeraatkar, Salar Sajedi, Sanaz Kaviani, Mohsen Taheri, Hadi Khanmohammadi, Saeed Sarkar, Mohammad Reza Ay
Proceeding and Conference Record
2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), P 1-3

52.  A Comparison Study on Two Novel Statistical Reconstruction Algorithms Developed for Slit-Hole Collimation Data in Small Animal SPECT Imaging

H Mahani, G Raisali, A Kamali-Asl, M Ay
Proceeding and Conference Record
EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING, 2017, Vol 44, P S434-S434

53.  Cardiac contraction motion compensation in gated Myocardial Perfusion SPECT

N Salehi, M Farahani, E Fatemizadeh, S Farzanefar, M Ay
Proceeding and Conference Record
EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING, 2017

54.  Design optimization of partial cylindrical PET scanner based on trapezoid-shaped block detector and monolithic crystals using Monte Carlo simulation

P Sheikhzadeh, H Ghadiri, P Geramifar, P Ghaffarian, M Ay
Proceeding and Conference Record
EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING, 2017

55.  Development of low dose CT protocols with acceptable CT image quality for CTAC of PET data: Phantom Study

Z Mojabi, P Ghafarian, H Ghadiri, M Bakhshayeshkaram, M Ay
Proceeding and Conference Record
EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING, 2017

56.  Evaluation of the Impact of Using TOF Technique on Metal Artifact Reduction in PET/CT Images

R Sharifpour, P Ghafarian, MR Ay
Proceeding and Conference Record
EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING, 2017

57.  Grid block design based on monte carlo simulated dosimetry, the linear quadratic and Hug–Kellerer radiobiological models

Somayeh Gholami, Hassan Ali Nedaie, Francesco Longo, Mohammad Reza Ay, Sharifeh A Dini, Ali S Meigooni
Peer-reviewed Journal Publication
Journal of medical physics, 2017, Vol 42, pp 213

58.  Is the averaged SUV from several hottest voxels an alternative to SUV peak for quantification of large heterogeneous or small lesions in oncological PET imaging?

A Ketabi, P Ghafarian, S Masjoodi, MA Mosleh-Shirazi, MR Ay
Proceeding and Conference Record
EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING, 2017

59.  Monte Carlo Based Performance estimation of breast PET due to reduction of the ring diameter

A Emami, H Ghadiri, P Ghafarian, M Ay
Proceeding and Conference Record
EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING, 2017

60.  Optimal quantitative SUV metrics over wide range of lesion sizes in advanced image reconstruction (TOF and PSF) for PET

I Shiri, P Ghafarian, S Ashrafinia, A Bitarafan-Rajabi, M Ay, A Rahmim
Proceeding and Conference Record
EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING, 2017, Vol 44, P S427-S428

61.  Optimization of the crystal thickness for a monolithic LYSO animal PET detector with anger and CSE positioning method using Monte Carlo simulation

A Sanaat, M Shamsaie, B Teymorian, R Hoshemi, M Ay
Proceeding and Conference Record
EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING, 2017, Vol 44, p 431-432

62.  Quantification and Reduction of respiratory induced errors in attenuation correction of PET data using respiration averaged CT: a simulation study

P Ghaffarian, F Fatemi, P Geramifar, M Ay
Proceeding and Conference Record
EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING, 2017

63.  Simultaneous High-Sensitivity High-Resolution Molecular SPECT Imaging with Spinning Slit-Hole Collimator: A Monte Carlo Simulation Study

M Ay, H Mahani, G Raisali, A Kamali-Asl
Proceeding and Conference Record
EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING, 2017, Vol 44, P S389-S390

64.  Sub-centimeter lesion detectability in Point-spread function (PSF) and Time of flight (TOF) reconstructed PET images

I Shiri, P Ghafarian, A Bitarafan-Rajabi, M Ay
Proceeding and Conference Record
EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING, 2017, Vol 44, P S438-S439

65.  The Influence of Crystal Material and Size on the Sensitivity of Recently Developed SiPM Based Animal PET Scanner: a Monte Carlo Study

P Ghahramani, N Zeraatkar, N Vosoughi, MR Ay
Proceeding and Conference Record
EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING, 2017, Vol 44, PS429-S430

66.  Volume-based assessment of different image reconstruction algorithms and thresholds for FDG-PET/CT based on dose-painting concept

P Ghafarian, A Ketabi, MA Mosleh-Shirazi, MR Ay
Proceeding and Conference Record
EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING, 2017, Vol 44, P S758-S758

67.  Compton scatter tomography in TOF-PET

Hamidreza Hemmati, Alireza Kamali-Asl, Mohammadreza Ay, Pardis Ghafarian
Peer-reviewed Journal Publication
Physics in Medicine & Biology,2017, Vol 62, pp 7641

68.  Development and calibration of a new gamma camera detector using large square Photomultiplier Tubes

N Zeraatkar, S Sajedi, B Teimourian Fard, S Kaviani, A Akbarzadeh, MH Farahani, S Sarkar, MR Ay
Peer-reviewed Journal Publication
Journal of Instrumentation,2017, Vol 12

69.  Development and validation of an accurate GATE model for NeuroPET scanner

Peyman Sheikhzadeh, Hamid Sabet, Hossein Ghadiri, Parham Geramifar, Hojjat Mahani, Pardis Ghafarian, Mohammad Reza Ay
Peer-reviewed Journal Publication
Physica Medica, 2017,Vol.40, pp59-65

70.  Spinning slithole collimation for high-sensitivity small animal SPECT: Design and assessment using GATE simulation

Hojjat Mahani, Gholamreza Raisali, Alireza Kamali-Asl, Mohammad Reza Ay
Peer-reviewed Journal Publication
Physica Medica, 2017, Vol 40, pp 42-50

71.  Implementation of absolute quantification in small‐animal SPECT imaging: Phantom and animal studies

Shabnam Khorasani Gerdekoohi, Naser Vosoughi, Kaveh Tanha, Majid Assadi, Pardis Ghafarian, Arman Rahmim, Mohammad Reza Ay
Peer-reviewed Journal Publication
Journal of applied clinical medical physics, 2017, Vol 18, pp 215-223

72.  How crystal configuration affects the position detection accuracy in pixelated molecular SPECT imaging systems?

Hojjat Mahani, Gholamreza Raisali, Alireza Kamali-Asl, Mohammad Reza Ay
Peer-reviewed Journal Publication
Nuclear Science and Techniques, 2017, Vol 28, pp 47

73.  Implementation of absolute quantification in small-animal SPECT imaging: Phantom and animal studies

Shabnam Khorasani Gerdekoohi, Naser Vosoughi, Kaveh Tanha, Majid Assadi, Pardis Ghafarian, Arman Rahmim, Mohammad Reza Ay
Peer-reviewed Journal Publication
MEDICAL IMAGING, 2017, pp 1-9

74.  Evaluation of radiation exposure to staff and environment dose from [18F]-FDG in PET/CT and cyclotron center using thermoluminescent dosimetry

S Zargan, P Ghafarian, A Shabestani Monfared, AA Sharafi, M Bakhshayeshkaram, MR Ay
Peer-reviewed Journal Publication
Journal of biomedical physics & engineering, 2017,Vol 7

75.  Quantification of the impact of TOF and PSF on PET images using the noise-matching concept: clinical and phantom study

M Shekari, P Ghafarian, S Ahangari, MR Ay
Peer-reviewed Journal Publication
Nuclear Science and Techniques, 2017, Vol 28, pp 167

76.  Collimator-Detector Response Compensation in Molecular SPECT Reconstruction using STIR Framework?

Hojjat Mahani, Gholamreza Raisali, Alireza Kamali-Asl, Mohammad Reza Ay
Peer-reviewed Journal Publication
Iranian Journal of Nuclear Medicine and Molecular Imaging, 2017, Vol 25, pp 26-34

77.  Impact of Time-of-Flight and Point-Spread-Function for Respiratory Artifact Reduction in PET/CT Imaging: Focus on Standardized Uptake Value

Roya Sharifpour, Pardis Ghafarian, Mehrdad Bakhshayesh-Karam, Hamidreza Jamaati, Mohammad Reza Ay
Peer-reviewed Journal Publication
Tanaffos ,2017,Vol 16, pp 127

78.  Monte Carlo optimization of crystal configuration for pixelated molecular SPECT scanners

Hojjat Mahani, Gholamreza Raisali, Alireza Kamali-Asl, Mohammad Reza Ay
Peer-reviewed Journal Publication
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2017, Vol 844, pp 1-6

79.  Single STE-MR Acquisition in MR-Based Attenuation Correction of Brain PET Imaging Employing a Fully Automated and Reproducible Level-Set Segmentation Approach

Anahita Fathi Kazerooni, Mohammad Reza Ay, Saman Arfaie, Parisa Khateri, Hamidreza Saligheh Rad
Peer-reviewed Journal Publication
Molecular Imaging & Biology, 2017, Vol 19, pp 143-152

80.  A hybrid tracking system for image-guided spine surgery using a tracked mobile C-arm: a phantom study

P. Ghobadi, A. Ahmadian, H. saberi, M.R. Ay, M. Addolghafar and K. Amini
Peer-reviewed Journal Publication
Turk J Elec Eng & Comp Sci, 2017, Vol. 25, pp 434-448.

81.  Development and Evaluation of Image Reconstruction Algorithms for a Novel Desktop SPECT System

Navid Zeraatkar, Arman Rahmim, Saeed Sarkar, Mohammad Reza Ay
Peer-reviewed Journal Publication
Asia Oceania Journal of Nuclear Medicine and Biology,2017, Vol 5,pp 120

82.  New approach for calibration of pixelated scintillation detectors of intraoperative gamma cameras

Afshin Akbarzadeh, Valiallah Saba, Mohammad Reza Ay
Peer-reviewed Journal Publication
Iranian Journal of Nuclear Medicine and Molecular Imaging, 2017, Vol. 25, No. 1, pp 34-42.

83.  MR-guided attenuation map for prostate PET-MRI: an intensity and morphologic-based segmentation approach for generating a five-class attenuation map in pelvic region

M. Shandiz, H. Saligeh Rad, P. Ghafarian, M. Bakhshaysh Karam and M.R. Ay
Peer-reviewed Journal Publication
Ann Nucl Med. 2017, Vol 31, pp 29-39

Abstract:

PURPOSE:

Prostate imaging is one of the major application of hybrid PET/MRI systems. Inaccurate attenuation maps (µ-maps) derived by direct segmentation (SEG) in which the cortical bone is ignored and the volume of the air in cavities is underestimated is the main challenge of commercial PET/MRI systems for the quantitative analysis of the pelvic region. The present study considered the cortical bone and air cavity along with soft tissue, fat, and background air in the µ-map of the pelvic region using a method based on SEG. The proposed method uses a dedicated imaging technique that increases the contrast between regions and a hybrid segmentation method to classify MR images based on intensity and morphologic characteristics of tissues, such as symmetry and similarity of bony structures.

PROCEDURES:

Ten healthy volunteers underwent MRI and ultra-low dose CT imaging. The dedicated MR imaging technique uses the short echo time (STE) based on the conventional sequencing implemented on a clinical 1.5T MRI scanner. The generation of a µ-map comprises the following steps: (1) bias field correction; (2) hybrid segmentation (HSEG), including segmenting images into clusters of cortical bone-air, soft tissue, and fat using spatial fuzzy c-means (SFCM), and separation of cortical bone and internal air cavities using morphologic characteristics; (3) the active contour approach for the separation of background air; and (4) the generation of a five-class μ-map for cortical bone, internal air cavity, soft tissue, fat tissue, and background air. Validation was done by comparison with segmented CT images.

RESULTS:

The Dice and sensitivity metrics of cortical bone structures and internal air cavities were 72 ± 11 and 66 ± 13 and 73 ± 10 and 68 ± 20 %, respectively. High correlation was observed between CT and HSEG-based µ-maps (R 2 > 0.99) and the corresponding sinograms (R 2 > 0.98).

CONCLUSIONS:

Currently, pelvis µ-maps provided by the current PET/MRI systems and the ultra-short echo time and atlas-based methods tend to be inaccurate. The proposed method acceptably generated a five-class μ-map using only one image.

KEYWORDS:

MRI-base attenuation correction; Morphologic characteristics-based segmentation; PET/MRI; Prostate imaging; STE pulse sequence

84.  Development and characterization of a compact hand-held gamma probe system, SURGEOGUIDE, based on NEMA NU3-2004 standards

S. Kaviani, N. Zeraatkar,S. Sajedi, N. Gorjizadeh, M.H. Farahani, P. Ghafarian,G. El Fakhri, H. Sabete and M.R. Ay
Peer-reviewed Journal Publication
Journal of Instrumentation, 2016, Vol 11

85.  Effect of TOF and PSF in detection of lymph node metastases in head and neck of PET/CT images

P Ghafarian, A Ketabi, A Doroudinia, M Bakhshayesh Karam, MR Ay
Proceeding and Conference Record
EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING, 2016, Vol 43, pp s507

86.  Design and development of a dedicated portable gamma camera system for intra-operative imaging

S. Kaviani, N. Zeraatkar, S. Sajedi, A. Akbarzadeh, N. Gorjizadeh, M. H. Farahani, B. Teimourian, P. Ghafarian, H. Sabet and M.R. Ay
Peer-reviewed Journal Publication
Phys Med. 2016 Jul;32(7):889-97. doi: 10.1016/j.ejmp.2016.06.004. Epub 2016 Jun 23

Abstract

PURPOSE:

We developed a high performance portable gamma camera platform dedicated to identification of sentinel lymph nodes (SLNs) and radio-guided surgery for cancer patients. In this work, we present the performance characteristics of SURGEOSIGHT-I, the first version of this platform that can intra-operatively provide high-resolution images of the surveyed areas.

METHODS:

At the heart of this camera, there is a 43×43 array of pixelated sodium-activated cesium iodide (CsI(Na)) scintillation crystal with 1×1mm(2) pixel size and 5mm thickness coupled to a Hamamatsu H8500 flat-panel multi-anode (64 channels) photomultiplier tube. The probe is equipped with a hexagonal parallel-hole lead collimator with 1.2mm holes. The detector, collimator, and the associated front-end electronics are encapsulated in a common housing referred to as head.

RESULTS:

Our results show a count rate of ∼41kcps for 20% count loss. The extrinsic energy resolution was measured as 20.6% at 140keV. The spatial resolution and the sensitivity of the system on the collimator surface was measured as 2.2mm and 142cps/MBq, respectively. In addition, the integral and differential uniformity, after uniformity correction, in useful field-of-view (UFOV) were measured 4.5% and 4.6%, respectively.

CONCLUSIONS:

This system can be used for a number of clinical applications including SLN biopsy and radiopharmaceutical-guided surgery.

Keywords:

Sentinel lymph node (SLN), Lymphoscintigraphy, SURGEOSIGHT-I, Breast cancer, Intra-operative gamma camera

87.  Design, optimization and performance evaluation of BM-PET: A simulation study

Peyman Sheikhzadeh, Hamid Sabet, Hossein Ghadiri, Parham Geramifar, Pardis Ghafarian, Mohammad Reza Ay
Peer-reviewed Journal Publication
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

88.  Design and Assessment of a Novel SPECT System for Desktop Open-Gantry Imaging of Small Animals: a Monte Carlo Study

N. Zeraatkar, M. H. Farahani, S. Sarkar, A. Rahmim and M.R. Ay
Peer-reviewed Journal Publication
Med Phys. 2016 May;43(5):2581. doi: 10.1118/1.4947127

Abstract

PURPOSE:

Given increasing efforts in biomedical research utilizing molecular imaging methods, development of dedicated high-performance small-animal SPECT systems has been growing rapidly in the last decade. In the present work, we propose and assess an alternative concept for SPECT imaging enabling desktop open-gantry imaging of small animals.

METHODS:

The system, PERSPECT, consists of an imaging desk, with a set of tilted detector and pinhole collimator placed beneath it. The object to be imaged is simply placed on the desk. Monte Carlo (MC) and analytical simulations were utilized to accurately model and evaluate the proposed concept and design. Furthermore, a dedicated image reconstruction algorithm, finite-aperture-based circular projections (FABCP), was developed and validated for the system, enabling more accurate modeling of the system and higher quality reconstructed images. Image quality was quantified as a function of different tilt angles in the acquisition and number of iterations in the reconstruction algorithm. Furthermore, more complex phantoms including Derenzo, Defrise, and mouse whole body were simulated and studied.

RESULTS:

The sensitivity of the PERSPECT was 207 cps/MBq. It was quantitatively demonstrated that for a tilt angle of 30°, comparable image qualities were obtained in terms of normalized squared error, contrast, uniformity, noise, and spatial resolution measurements, the latter at ∼0.6 mm. Furthermore, quantitative analyses demonstrated that 3 iterations of FABCP image reconstruction (16 subsets/iteration) led to optimally reconstructed images.

CONCLUSIONS:

The PERSPECT, using a novel imaging protocol, can achieve comparable image quality performance in comparison with a conventional pinhole SPECT with the same configuration. The dedicated FABCP algorithm, which was developed for reconstruction of data from the PERSPECT system, can produce high quality images for small-animal imaging via accurate modeling of the system as incorporated in the forward- and back-projection steps. Meanwhile, the developed MC model and the analytical simulator of the system can be applied for further studies on development and evaluation of the system.

89.  Is Grid Therapy Useful for all Tumors and Every Grid Block Design?

S. Gholami, H. Nedaie, F. Longo, M. R. Ay, S. Wright and A. S. Meigooni
Peer-reviewed Journal Publication
J Appl Clin Med Phys. 2016 Mar 8;17(2):6015

Abstract

Grid therapy is a treatment technique that has been introduced for patients with advanced bulky tumors. The purpose of this study is to investigate the effect of the radiation sensitivity of the tumors and the design of the grid blocks on the clinical response of grid therapy. The Monte Carlo simulation technique is used to determine the dose distribution through a grid block that was used for a Varian 2100C linear accelerator. From the simulated dose profiles, the therapeutic ratio (TR) and the equivalent uniform dose (EUD) for different types of tumors with respect to their radiation sensitivities were calculated. These calculations were performed using the linear quadratic (LQ) and the Hug-Kellerer (H-K) models. The results of these calculations have been validated by comparison with the clinical responses of 232 patients from different publications, who were treated with grid therapy. These published results for different tumor types were used to examine the correlation between tumor radiosensitivity and the clinical response of grid therapy. Moreover, the influence of grid design on their clinical responses was investigated by using Monte Carlo simulations of grid blocks with different hole diameters and different center-to-center spacing. The results of the theoretical models and clinical data indicated higher clinical responses for the grid therapy on the patients with more radioresistant tumors. The differences between TR values for radioresistant cells and radiosensitive cells at 20 Gy and 10 Gy doses were up to 50% and 30%, respectively. Interestingly, the differences between the TR values with LQ model and H-K model were less than 4%. Moreover, the results from the Monte Carlo studies showed that grid blocks with a hole diameters of 1.0 cm and 1.25 cm may lead to about 19% higher TR relative to the grids with hole diameters smaller than 1.0 cm or larger than 1.25 cm (with 95% confidence interval). In sum-mary, the results of this study indicate that grid therapy is more effective for tumors with radioresistant characteristics than radiosensitive tumors.

90.  Reduction of Respiratory Induced Artefact in PET/CT Images using TOF Reconstruction

R. Sharif Pour, P. Ghafarian, A. Doroudinia, M. Bakhshayesh Karam and M. R. Ay
Published Abstract
ACNM 2016

Abstract

Objectives:

The aim of this study was to investigate the effect of time-of-flight (TOF) and point-spread function (PSF) for quantitative and qualitative PET/CT image analysis in relation to decrease respiratory artifact in diaphragmatic region.

Methods:

29 patients with uptake time 61±2 min and injection of 327.5 MBq (range 261–350 MBq) 18F-FDG were scanned with Discovery 690 GE PET/CT scanner, equipped with 64-slice CT. All of the lesions were in the diaphragmatic region including: the lung lower lobes, liver and stomach in patients with extended white band artefact. For quantitative measurement NEMA phantom were also utilized. The PET images were retrospectively reconstructed using HD (Fully 3D Iterative Reconstruction)+PSF and TOF+ PSF algorithm with various iterations, subsets and post smoothing filters. A semi-quantitative analysis was performed using SUVmax and SUVmean with 50% threshold. We also considered image quality using coefficient of variance (COV) in the liver in clinical study, the signal-to-noise ratio (SNR) and contrast to background measurements in each lesions. The PET/CT images reviewed by two expert physicians.

Results:

In the phantom study, SUVmean illustrated the more convenient value in related to SUVmax when TOF+PSF algorithm applied with increase of post filter from 4.4 mm to 6.4mm. In clinical study, the COV was decreased 7.4%±1.3% when TOF+PSF were compared with non-TOF image. The SUVmax trend to higher value with relative difference 11.3% (range: 0.5%–25.1%) when TOF and non-TOF images were evaluated. It was interesting that using appropriate TOF reconstruction parameter increased the SNR up 65.6% (Range: 7.0%–194.7%). The combination of TOF and PSF decreased the lesion size on PET images 33.0%, 25.7% and 24.5% in sagital, coronal and axial view respectively when compared with HD+PSF algorithm. According to balance among the SNR, contrast, noise and visual assessment, the optimal images were obtained with TOF+PSF with FWHM between 5.2 to 6.4 mm.

Conclusion:

A little overestimation in SUVmax versus to SUV mean 50% was observed, when PSF with combination of either VPHD or TOF was used. TOF with PSF improved white band artifact in diaphragmatic region remarkably, increased lesion delectability, and altered lesion size in PET images. It is noteworthy that the variation in SUV and lesion size is strongly dependent to the proximity of the lesions to the artefact region and it is highly recommended that to attain optimal image quality, combination of low iteration number and utilizing appropriate Gaussian filter is necessary because noise and false positive findings could be dominant with small-FWHM post filter.

91.  Hybrid Imaging, PET/CT, in HANDBOOK OF SMALL ANIMAL IMAGING, Preclinical Imaging, Therapy, and Applications

M.R. Ay and N. Ghazanfari
Book Chapter
George C. Kagadis et al. , Editors. 2016, Tylor & Francis Books, Inc.
Mohammad Reza Ay and Nafiseh Ghazanfari
Introduction to Combining MRI with PET

92.  Introducing the HeliGuide: Urea Breath Tests System for Detecting Helicobacter Pylori

Aram Radnia, MohammadHossein Farahani, C Hoorvash, MohammadReza Ay
Peer-reviewed Journal Publication
Frontiers in Biomedical Technologies,2015, Vol 2,pp 115-117

93.  How gamma camera’s head-tilts affect image quality of a nuclear scintigram?

Hojjat Mahani, Alireza Kamali-Asl, MohammadReza Ay
Peer-reviewed Journal Publication
Frontiers in Biomedical Technologies, 2015, Vol 1

94.  The influence of PET and CT misalignment due to respiratory motion on the cardiac PET/CT imaging: a simulation study

Pardis Ghafarian, MohammadReza Ay
Peer-reviewed Journal Publication
Frontiers in Biomedical Technologies,2015, Vol 1

95.  Acceptance Test of the first Hospital Cyclotron for Production of PET tracers in Iran

P. Ghafarian, S. M. Khamesi1, M. R. Golrokh Nodehi and M. R. Ay
Published Abstract
World Congress on Medical Physics & Biomedical Engineering, 7-12 June 2015, Toronto, Canada, p 518

96.  An alternate mathematical modeling of image formation, and framework for performance analysis of positioning algorithms in the scintillation camera

S. Hosseini, M. H. Farahani and M. R. Ay
Published Abstract
World Congress on Medical Physics & Biomedical Engineering, 7-12 June 2015, Toronto, Canada, p 103

97.  Can Pacemaker and ICD degrade CT-Based Attenuation Corrected cardiac SPECT images?

Z. Etemadi, A. Bitaran Rajabi, H. Malek, P. Ghafarian, N. Zeraatkar and M.R. Ay
Published Abstract
World Congress on Medical Physics & Biomedical Engineering, 7-12 June 2015, Toronto, Canada, p 132

98.  Correction of Metal Artefacts Induced from Pacemaker and ICD Leads in CT-Based Attenuation Correction of Cardiac SPECT data

M. R. Ay, Z. Etemadi, A. Bitarafan-Rajabi, H. Malek, N. Zeraatkar and P. Ghafarian
Published Abstract
World Congress on Medical Physics & Biomedical Engineering, 7-12 June 2015, Toronto, Canada, p 522

99.  Design, modeling and performance evaluation of a small animal Micro-CT scanner: A Monte Carlo study

S. Nezhaddehghani1, S. Sarkar, and M. R. Ay
Published Abstract
World Congress on Medical Physics & Biomedical Engineering, 7-12 June 2015, Toronto, Canada, p 97

100.  Generating a four-class attenuation map for MR-based attenuation correction of PET data in pelvis region using an automatic segmentation protocol

H. Saligheh Rad, M. Shirin Shandiz, P. Ghafarian, M. H. Arabi, M. Bakhshayeshkaram, N. Shafiei and M. R. Ay
Published Abstract
World Congress on Medical Physics & Biomedical Engineering, 7-12 June 2015, Toronto, Canada, p 201

101.  Generation of 4-Class Attenuation Map for MRI Based Attenuation Correction of PET Data in the Head Area Using a Novel Combination of STE/DIXON-MRI and FCM Clustering

P. Khateri, H. Saligheh Rad, A. Homayoun Jafari, A. Fathi, A. Akbarzadeh, M. Shojae Moghadam, A. Aryan, P. Ghafarian and M.R. Ay
Published Abstract
World Congress on Medical Physics & Biomedical Engineering, 7-12 June 2015, Toronto, Canada, p 371

102.  Impact of Point spread function modeling on tumor quantification in clinical PET/CT imaging

S. Ahangari1, P. Ghafarian, M. Bakhshayeshkaram and M. R. Ay
Published Abstract
World Congress on Medical Physics & Biomedical Engineering, 7-12 June 2015, Toronto, Canada, p 133

103.  Measurement of Photon and Neutron Dose Distribution in Cyclotron Bunker During F18 and N13 Production

P. Ghafarian, S. M. Khamesi, M. R. Golrokh Nodehi and M.R. Ay
Published Abstract
World Congress on Medical Physics & Biomedical Engineering, 7-12 June 2015, Toronto, Canada, p 606

104.  Monte Carlo Simulation of X-ray Spectra in Computed Tomography Scanner using GATE

M. R. Ay, S. Nezhaddehghani1, and S. Sarkar
Published Abstract
World Congress on Medical Physics & Biomedical Engineering, 7-12 June 2015, Toronto, Canada, p 331

105.  Optimal Pixelated Crystal for a Molecular SPECT Scanner: A GATE Monte Carlo Study

M. R. Ay, H. Mahani, G. Raisali, and A. Kamali-Asl
Published Abstract
World Congress on Medical Physics & Biomedical Engineering, 7-12 June 2015, Toronto, Canada, p 200

106.  Spinning Knife-Edge Slit-Hole: a Novel Collimation for High-Sensitivity Molecular SPECT

H. Mahani, G. Raisali, A. Kamali-Asl and M.R. Ay
Published Abstract
World Congress on Medical Physics & Biomedical Engineering, 7-12 June 2015, Toronto, Canada, p 200

107.  The Impact of time of flight algorithm and PSF modeling on standard uptake value in clinical PET/CT imaging

M. Shekari, P. Ghafarian, M. Bakhshayeshkaram and M. R. Ay
Published Abstract
World Congress on Medical Physics & Biomedical Engineering, 7-12 June 2015, Toronto, Canada, p 132

108.  TLD Measurement of Absorbed Dose of Workers in PET/CT Department

P. Ghafarian, S. Zargan, A. Shabestani Monfared, A. Sharafi, M. Bakhshayeshkaram and M.R. Ay
Published Abstract
World Congress on Medical Physics & Biomedical Engineering, 7-12 June 2015, Toronto, Canada, p109

109.  An optimal Grid block design for spatially fractionated radiation therapy

S. Gholami S , H. Nedaie, F. Longo, M. R. Ay, AS. Meigooni
Published Abstract
ESTRO 2015

110.  Generation of a Four-Class Attenuation Map for MRI-Based Attenuation Correction of PET Data in the Head Area Using a Novel Combination of STE/Dixon-MRI and FCM Clustering

P. Khateri, H. Saligheh Rad, A. H. Jafari, A. Fathi Kazerooni, A. Akbarzadeh, M. Shojae Moghadam, A. Aryan, P. Ghafarian, M. R. Ay
Peer-reviewed Journal Publication
Mol Imaging Biol. 2015 Dec;17(6):884-92. doi: 10.1007/s11307-015-0849-1

Abstract

PURPOSE:

The aim of this study is to generate a four-class magnetic resonance imaging (MRI)-based attenuation map (μ-map) for attenuation correction of positron emission tomography (PET) data of the head area using a novel combination of short echo time (STE)/Dixon-MRI and a dedicated image segmentation method.

PROCEDURES:

MR images of the head area were acquired using STE and two-point Dixon sequences. μ-maps were derived from MRI images based on a fuzzy C-means (FCM) clustering method along with morphologic operations. Quantitative assessment was performed to evaluate generated MRI-based μ-maps compared to X-ray computed tomography (CT)-based μ-maps.

RESULTS:

The voxel-by-voxel comparison of MR-based and CT-based segmentation results yielded an average of more than 95 % for accuracy and specificity in the cortical bone, soft tissue, and air region. MRI-based μ-maps show a high correlation with those derived from CT scans (R (2) > 0.95).

CONCLUSIONS:

Results indicate that STE/Dixon-MRI data in combination with FCM-based segmentation yields precise MR-based μ-maps for PET attenuation correction in hybrid PET/MRI systems.

KEYWORDS:

Attenuation correction; Attenuation map; FCM technique; PET/MRI; STE pulse sequence

111.  Impact of the Radiation Sensitivity of Tumor and Geometric Design of the GRID Block On the Clinical Response of Grid Therapy

S. Gholami, AS. Meigooni, H. Nedaie, F. Longo M. R. Ay
Published Abstract
Med. Phys. 42, 3440 (2015); http://dx.doi.org/10.1118/1.4924823

Abstract

Purpose:

The spatially fractionated radiation therapy (Grid therapy) is a novel technique that has been recently introduced for treatments of the patients with advanced bulky tumors. The purpose of this study is to investigate the effect of the radiation sensitivity of tumor and Grid block design on the clinical response of the Grid therapy.

Methods:

The Geant4 toolkit is used to simulate a Varian2100C linear accelerator with the block-based Grid. The dose profile has been utilized to calculate the Therapeutic Ratio (TR) and Equivalent Uniform Dose (EUD) for different types of tumors. These calculations were performed with respect to their radiation sensitivities using Linear Quadratic model (LQ). Clinical responses of few hundred patients from different publications that were treated with Grid therapy, have been used to validate correlation between tumor radiation sensitivity and clinical response of Grid therapy. Moreover, the influence of Grid design on clinical response of this radiation technique was investigated with using Monte Carlo simulation of a Grid block with different hole-diameters of 0.5 cm, 0.75 cm, 1.25 cm, and 1.5 cm. The Geometrical Sparing Factor (GSF) was considered to compare the results from different Grid designs.

Results:

The higher clinical response of Grid therapy for more radio-resistant tumors was confirmed in both theoretical assumptions and clinical outcomes. In addition, the results indicate that the Grid hole diameter have more effect on increasing the TR in comparison with the hole center-to-center distance effect. From this Monte Carlo study, a Grid design with the hole diameter between 1.25 cm and 1.5 cm with GSF value of 0.90 is recommended.

Conclusion:

Grid Therapy is more effective for more radio-resistant tumors.The optimum results of the Grid therapy depend on selection of the appropriate Grid design.This study is a first step toward clarifying some important aspects in a clinical response of spatially fractionated radiation therapy.

112.  Monte Carlo Calculation of Neutron Doses to Organs of a Female Undergoing A Pelvic 18 MV Irradiation

M. Zabihzadeh, S.R. Mahdavi, M.R. Ay and Z. Shakarami
Peer-reviewed Journal Publication
Biomedical & Pharmacology Journal, 2015, Vol. 8, pp 65-71

113.  Monte Carlo-based Assessment of the Trade-off between Spatial Resolution, Field-of-View and Scattered Radiation in the Variable Resolution X-ray CT Scanner

H. Arabi, A.R. Kamali Asl, M. R. Ay and H. Zaidi
Peer-reviewed Journal Publication
Phys Med, 2015, Vol. 31, pp 510-516

114.  Optimizing Image Reconstruction Parameters in Time of Flight PET/CT Imaging: a Phantom Study

M. Shekari, P. Ghafarian, S. Ahangari, H. Ghadiri, M. Bakhshayeshkaram and M.R. Ay
Peer-reviewed Journal Publication
2015, Vol. 2, No. 3, pp 146-154

115.  The Effects of Backscattered Radiation into Beam Monitor Chamber: Study of 6 and 18 MV Conventional and Removed Flattening Filter Clinical Accelerator

M. Zabihzadeh, S.R. Mahdavi, M.R. Ay and Z. Shakarami
Peer-reviewed Journal Publication
BIOSCIENCES BIOTECHNOLOGY RESEARCH ASIA, 2015, Vol. 12, pp 25-36

116.  The Impact of Point Spread Function Modeling on Scan Duration in PET Imaging

S. Ahangari, P. Ghafarian, M. Shekari, H. Ghadiri, M. Bakhshayeshkaram and M.R. Ay
Peer-reviewed Journal Publication
Frontiers in Biomedical Technologies, 2015, Vol. 2, No. 3, pp 137-145

117.  Design and development of small fieldof view portable gamma camera for localization of sentinel lymph nodes

V. Moji, N. Zaratkar, S. Sajedi, A. Akbarzadeh, B. Timourian, M.H. Farahani and M. R. Ay
Published Abstract
18th Iranian Conference of Nuclear Medicine, Tehran, Iran, 12-14 November 2104, pp. 70

118.  Development of a hybrid small animal SPECT/CT scanner:a Monte Carlo study

S. Nerzhaddehghani, S. Sarkar and M.R. Ay
Published Abstract
18th Iranian Conference of Nuclear Medicine, Tehran, Iran, 12-14 November 2104, pp. 71

119.  Experimental measurement of absorbed dose using TLD for radiation workers in PET/CT department

S. Zargan, A. Monfared, P. Ghafarian, A. K. Sharafi, M. Bakhshayesh karam and M.R. Ay
Published Abstract
18th Iranian Conference of Nuclear Medicine, Tehran, Iran, 12-14 November 2104, pp. 157

120.  Monte Carlo-based characterization of HiReSPECT scanner: a dedicatd small animal SPECT imaging system

H. Mahani, G. Raisali, A. Kamali asl and M.R. Ay
Published Abstract
18th Iranian Conference of Nuclear Medicine, Tehran, Iran, 12-14 November 2104, pp. 73

121.  Optimizing the acquisition time in whole body PET/CT imaging

S. Ahanghari, P. Ghafarian, M. Sherkari, M. Bakhshayesh karam and M.R. Ay
Published Abstract
18th Iranian Conference of Nuclear Medicine, Tehran, Iran, 12-14 November 2104, pp. 75

122.  Performance evaluation of surgical gamma probe for sentinel lymph node localization based on NMA NU3-2004 standard

N. Gorjizadeh, S. Farzanehfar, A. Kaviani, N. Zeraatkar, M. H. Farhani, S. Sajesi and M.R. Ay
Published Abstract
18th Iranian Conference of Nuclear Medicine, Tehran, Iran, 12-14 November 2104, pp. 77

123.  Quantification of inter-crystal scatter and penetration in HiReSPCT: a dedicated small animal SPCT imaging systm

H. Mahani, G. Raisali, A. Kamali asl and M.R. Ay
Published Abstract
18th Iranian Conference of Nuclear Medicine, Tehran, Iran, 12-14 November 2104, pp. 78

124.  A Fully Automated and Reproducible Level-set Segmentation Approach for Generation of MR-Based Attenuation Correction Map of PET Images in the Brain Employing Single STE-MR Imaging Modality

Fathi, M. H. Arbabi, M.R. Ay and H. Saligheh Rad
Published Abstract
PSMR 2014 MR-PET Workshop, Kos Island, Greece, 19-21 May 2014, EJNMMI Physics 2014, 1(Suppl 1):A48

125.  A hybrid method for generation of attenuation map for MR-based attenuation correction of PET data in prostate PET/MR imaging

M. Shirin Shandiz, M. H. Arabi, P. Ghafarian, M. Bakhshayesh Karam , H. Saligheh Rad and M.R. Ay
Published Abstract
PSMR 2014 MR-PET Workshop, Kos Island, Greece, 19-21 May 2014, EJNMMI Physics 2014, 1(Suppl 1):A77

126.  MR-Based Attenuation Map Generation in Short-TE MR Images of the Head Employing Spatial Fuzzy C-Means Clustering Approach

M. H. Arabi, A. Fathi, P. Khateri, M.R. Ay and H. Saligheh Rad
Published Abstract
PSMR 2014 MR-PET Workshop, Kos Island, Greece, 19-21 May 2014, EJNMMI Physics 2014, 1(Suppl 1):A49

127.  A Novel Segmentation Approach for Implementation of MRAC in Head PET/MRI Employing Short-TE MRI and 2-Point Dixon Method in a Fuzzy C-Means Framework

P. Khateri, H. Saligeh Rad, A.H. Jafari and M.R. Ay
Peer-reviewed Journal Publication
Nuclear Instrumentation Methods in Physics Research A, 2014, Vol. 734, No. 8, pp 171-174

128.  Classification of bones from MR images in torso PET-MR imaging using a statistical shape model

M. R. Ay, A. Akbarzadeh, A. Ahmadian and H. Zaidi
Peer-reviewed Journal Publication
Nuclear. Instrumentation Methods in Physics Research A, 2014, Vol. 734, pp 196-200

Abstract

There have been exclusive features for hybrid PET/MRI systems in comparison with its PET/CT counterpart in terms of reduction of radiation exposure, improved soft-tissue contrast and truly simultaneous and multi-parametric imaging capabilities. However, quantitative imaging on PET/MR is challenged by attenuation of annihilation photons through their pathway. The correction for photon attenuation requires the availability of patient-specific attenuation map, which accounts for the spatial distribution of attenuation coefficients of biological tissues. However, the lack of information on electron density in the MR signal poses an inherent difficulty to the derivation of the attenuation map from MR images. In other words, the MR signal correlates with proton densities and tissue relaxation properties, rather than with electron density and, as such, it is not directly related to attenuation coefficients. In order to derive the attenuation map from MR images at 511 keV, various strategies have been proposed and implemented on prototype and commercial PET/MR systems. Segmentation-based methods generate an attenuation map by classification of T1-weighted or high resolution Dixon MR sequences followed by assignment of predefined attenuation coefficients to various tissue types. Intensity-based segmentation approaches fail to include bones in the attenuation map since the segmentation of bones from conventional MR sequences is a difficult task. Most MR-guided attenuation correction techniques ignore bones owing to the inherent difficulties associated with bone segmentation unless specialized MR sequences such as ultra-short echo (UTE) sequence are utilized. In this work, we introduce a new technique based on statistical shape modeling to segment bones and generate a four-class attenuation map. Our segmentation approach requires a torso bone shape model based on principle component analysis (PCA). A CT-based training set including clearly segmented bones of the torso region of 20 clinical studies was designed. Using this training set, a bone atlas was trained taking advantage of PCA analysis. Our active shape segmentation technique uses the trained shape model to segment bones from user defined initial seed points. The segmentation algorithm was evaluated using 10 clinical datasets (aligned MR and CT pairs). The resulting attenuation maps were compared to corresponding attenuation maps derived from CT resulting in a mean relative difference less than 7%.

Keywords:

PET/MRI; MR bone segmentation; Attenuation correction; Whole-body imaging

129.  Derivation of attenuation map for attenuation correction of PET data in the presence of nanoparticulate contrast agents using spectral CT imaging

H. Ghadiri, MB Shiran, HR Soltanian-Zadeh, A. Rahmim, H. Zaidi and M.R. Ay
Peer-reviewed Journal Publication
Annals of Nuclear Medicine, 2014, Vol. 28, No. 6, pp 559-570

130.  Design and Development of a High Resolution Animal SPECT Scanner Dedicated for Rat and Mouse Imaging

S. Sajedi , N. Zeraatkar, V. Moji, M. H. Farahani, S. Sarkar, H. Arabi, B. Teymoorian, P. Ghafarian, A. Rahmim and M.R. Ay
Peer-reviewed Journal Publication
Nuclear. Instrumentation Methods in Physics Research A, 2014, Vol. 741, pp 169-176

131.  Experimental Evaluation of the Performance of HiReSPECT Scanner: a High-Resolution SPECT System for Small Animal Imaging

A. M. Pashazadeh, K. Tanha, F. Jafarian Dehkordi, M. Assadi, V. Moji , N. Zeraatkar and M.R. Ay
Peer-reviewed Journal Publication
Frontiers in Biomedical Technologies, 2014, Vol. 1, No. 3, pp 222-227

132.  How Gamma Camera’s Head-Tilts Affect Image Quality of a Nuclear Scintigram?

H. Mahani, A. Kamali-Asl, M.R. Ay
Peer-reviewed Journal Publication
Frontiers in Biomedical Technologies, 2014, Vol. 1, No. 4, pp 265-270

133.  Performance Evaluation of Newly Developed High Resolution Dual Head Animal SPECT System Based on NEMA NU2 2007 Standard

V. Moji, N. Zeraatkar, M.H. Farahani, M. Aghamiri, S. Sajedi, B. Teymorian, P. Ghafarian , S. Sarkar and M.R. Ay
Peer-reviewed Journal Publication
J Appl Clin Med Phys, 2014, Vol. 15, No. 6, pp 267-278

134.  Positron Emission Tomography: Physics, Instrumentation, Scanners and New Horizons

M.R. Ay and P. Geramifar
Book Chapter
2014, Royan Pazhoh, Inc., Tehran, Iran, ISBN-13: 9786007108543

135.  Quantification of PET and CT misalignment errors due to bulk motion in cardiac PET/CT imaging: Phantom and clinical studies

P. Ghafarian, M.R. Ay, A. Fard-Esfahani, A. Rahmim and H. Zaidi
Peer-reviewed Journal Publication
Frontiers in Biomedical Technologies, 2014, Vol. 1, No. 3, pp 159-167

136.  Resolution-Recovery-Embedded Image Reconstruction for a High-Resolution Animal SPECT System

N. Zeraatkar, S. Sajedi, M. H. Farahani, H. Arabi, S. Sarkar, P. Ghafarian, A. Rahmim and M.R. Ay
Peer-reviewed Journal Publication
Phys Med, 2014, Vol. 30, No. 7, pp 774-781

137.  The Influence of PET and CT Misalignment due to Respiratory Motion on the Cardiac PET/CT Imaging: a Simulation Study

P. Ghafarian, M.R. Ay
Peer-reviewed Journal Publication
Frontiers in Biomedical Technologies, 2014, Vol. 1, No. 4, pp 252-257

138.  Optical Flow Based Method for Generation of Virtual Average CT: A Simulation Study Using 4D XCAT Phantom

P. Geramifar, M. Shamsaie Zafarghandi and M.R. Ay
Published Abstract
European Association of Nuclear Medicine Annual Congress, 19-23 October 2013, Lyon, France. Eur J Nucl Med Mol, Vol 20, Issue 2

139.  Performance Evaluation of a Small Field of View Portable Gamma Camera for Localization of Sentinel Lymph Nodes

N. Gorjizadeh, N. Zeraatkar, A. Kaviani, S. Farzaneh far, M. H. Farahani, A. Akbarzadeh, S. Sajedi, B. Teimourian and M.R. Ay
Published Abstract
European Association of Nuclear Medicine Annual Congress, 19-23 October 2013, Lyon, France. Eur J Nucl Med Mol, Vol 20, Issue 2

140.  SURGEOGUIDE: a Gamma Probe for Localization of Sentinel Lymph Nodes

M.R. Ay, N. Zeraatkar, N. Gorjizadeh, S. Sajedi, H. Arabi, M. H. Farahani, B. Teimourian
Published Abstract
European Association of Nuclear Medicine Annual Congress, 19-23 October 2013, Lyon, France. Eur J Nucl Med Mol, Vol 20, Issue 2

141.  The Influence of Misalignment Artifact Due to Global and Respiratory Motion on Interpretation of Cardiac PET/CT Examination: Clinical and Phantom Studies

P. Ghafarian and M.R. Ay
Published Abstract
European Association of Nuclear Medicine Annual Congress, 19-23 October 2013, Lyon, France. Eur J Nucl Med Mol, , Vol 20, Issue 2

142.  Variation in Thoracic Lesions SUVmax as a Function of Respiratory Phase Based on the Optical Flow Motion Estimation: A Simulation Study Using 4D XCAT Phantom

P. Geramifar, M. Shamsaie Zafarghandi and M.R. Ay
Published Abstract
European Association of Nuclear Medicine Annual Congress, 19-23 October 2013, Lyon, France. Eur J Nucl Med Mol, Vol 20, Issue 2

143.  K-edge ratio method for identification of multiple nanoparticulate contrast agents by spectral CT imaging

H Ghadiri, M. R. Ay , M. B. Shiran, H. R. Soltanian-Zadeh and H Zaidi
Peer-reviewed Journal Publication
Br J Radiol. 2013 Sep; 86(1029): 20130308

144.  A fast and hardware mimicking analytic CT simulator

H Ghadiri, M B Shiran, H R Soltanian-Zadeh, A Rahmim and M R Ay
Proceeding and Conference Record
IEEE Nuclear Science Symposium & Medical Imaging Conference, Seoul, South Korea, 2013, pp 1-5

Abstract:

Different algorithms have been utilized for x-ray computed tomography (CT) simulation based on Monte Carlo technique, analytic calculation, or combination of them. Software packages based on Monte Carlo algorithm provide sophisticated calculations but the time consuming nature of them limits its applicability. Analytic calculation for CT simulation has been also evaluated in recent years. Due to ignoring basic physical processes, analytic methods have limited applications. In this study, a hardware mimicking algorithm has been developed to accurately model the CT imaging chain using analytic calculation. The model includes x-ray spectrum generation according to the pre-defined scanning protocol. The detector is designed to acquire the data either in integral or spectral modes. CT geometry can be used as parallel or fan beam with different sizes. Poisson noise model was applied to the acquired projection data. Varieties of projection-based computerized phantoms have been designed and implemented in the simulator. CT number and background noise of the simulated images have been compared with experimental data. On average, the relative difference between simulated and experimental HUs are 8.3%, 7.5%, and 8.0% for bone; 12.1%, 10.3%, and 7.8% for contrast agent; and 16.6%, 3.6%, and 5.2% for the background at 80 kVp/500 mAs, 120 kVp/250 mAs, and 140 kVp/125 mAs, respectively. The relative difference between simulated and experimental noise values vary between 2% to slightly less than 26%. For scanning and image generation with a computer equipped with Intel Core2 Quad CPU and 2.0 GB of RAM, the simulator takes about 32 seconds for generating a 512×512 single slice image when it is adjusted to acquire 900 projection angles with 20 mm slice thickness and 140kVp/200 mAs scanning protocol. The simulation time is independent of photon intensity.

145.  A Novel Segmentation Approach for Implementation of MRAC in Head and Neck PET/MRI Imaging Employing Short-TE MRI and 2-Point Dixon Method in Fuzzy C-Means Framework

P. Khateri, H. Salighe Rad, A.H. Jafari and M.R. Ay
Published Abstract
PSMR 2013 MR-PET Workshop, Jülich, Germany, 6-7 May –2013

146.  Classification of bones from MR images in torso PET-MR imaging using a statistical shape model

M.R. Ay, Akbarzadeh A, Ahmadian and Zaidi H
Published Abstract
PSMR 2013 MR-PET Workshop, Jülich, Germany, 6-7 May –2013

147.  A new energy mapping algorithm based on spectral CT images: application in PET/CT attenuation correction

H. Ghadiri, M.B. Shiran, H.R. Soltanian-Zadeh and M.R. Ay
Published Abstract
Iranian Congress of Nuclear Medicine, Shiraz, Iran, May 1-3, 2013

148.  Performance evaluation of HiReSPECT a dedicated animal SPECT system using modified NEMA standards

V.Moji, M. Aghamiri, H. Farahani, N. Zeratkar, S. Sajedi, B. Teymorian and M.R. Ay
Published Abstract
Iranian Congress of Nuclear Medicine, Shiraz, Iran, May 1-3, 2013

149.  Spatial Resolution and System Sensitivity in a Tilted-Head Planar-SPECT: a Monte Carlo Study

H. Mahani, A. R. Kamali-Asl, V. Moslemi, M.R. Ay
Published Abstract
Iranian Congress of Nuclear Medicine, Shiraz, Iran, May 1-3, 2013

150.  3D Prior Image Constrained Projection Completion for X-ray CT Metal Artifact Reduction

A. Mehranian, M. R. Ay, A. Rahmim and H. Zaidi
Peer-reviewed Journal Publication
IEEE Trans Nuclear Sciences, 2013, Vol. 60, No. 5, pp 3318-3332

151.  A novel non-linear recursive filter design for extracting high rate pulse features in nuclear medicine imaging and spectroscopy

S. Sajedi, A. Kamali Asl, M. R. Ay, M.H. Farahani and A. Rahmim
Peer-reviewed Journal Publication
Medical Engineers & Physics , 2013, Vol. 35, No.6, pp. 754-764

152.  An ordered-subsets proximal preconditioned gradient algorithm for edge-preserving PET image reconstruction

A. Mehranian, A. Rahmim, M. R. Ay, F. Kotasidis and H. Zaidi
Peer-reviewed Journal Publication
Medical Physics 2013, Vol. 40, No. 5, pp 052503-14

153.  EBT GHAFCROMIC film dosimetry in compensator-based intensity modulation radiation therapy

S. Vaezzadeh, M. Allahverdi, H. Nedaei, M. R. Ay, A. Shirazi and M. Yarahmadi
Peer-reviewed Journal Publication
Medical Dosimetry , 2013, Vol. 38, pp. 176-183

154.  Evaluation of whole-body MR to CT deformable image registration

A. Akbarzadeh, D. Gutierrez, A. Baskin, M. R. Ay, A. Ahmadian, N. Riahi Alam, K. Lövblad and H. Zaidi
Peer-reviewed Journal Publication
J Appl Clin Med Phys, 2013, Vol. 14, No. 4, pp 238-253

155.  Experimental assessment of the influence of beam hardening filters on image quality and patient dose in volumetric 64-slice x-ray CT scanners

M. R. Ay, A. Mehranian, A. Maleki, H. Ghadiri,P. Ghafarian and H. Zaidi
Peer-reviewed Journal Publication
Phys Med , 2013, Vol. 29, pp. 249-260

156.  MRI-guided attenuation correction in whole-body PET/MR: Assessment of the effect of bone attenuation

A. Akbarzadeh, M. R. Ay, A. Ahmadian, N. Riahi Alam and H. Zaidi
Peer-reviewed Journal Publication
Annals of Nuclear Medicine, 2013, Vol. 27, pp. 152-162

157.  Respiratory-Induced Errors in Tumor Quantification and Delineation in CT Attenuation Corrected PET Images: Effects of Tumor Size, Tumor Location and Respiratory Trace - A Simulation Study Using the 4D XCAT Phantom

P. Geramifar, M. Shamsaie Zafarghandi, P. Ghafarian, A. Rahmim and M. R. Ay
Peer-reviewed Journal Publication
Molecular Imaging & Biology, 2013, Vol. 15, No. 6, pp 655-665

158.  Smoothly Clipped Absolute Deviation (SCAD) Regularization for Compressed Sensing MRI Using an Augmented Lagrangian Scheme

A. Mehranian, H. Salighe Rad, A. Rahmim, M. R. Ay and H. Zaidi
Peer-reviewed Journal Publication
Magnetic Resonance Imaging, 2013, Vol. 31, No. 8, pp 1399-1411

159.  X-ray CT metal artifact reduction using wavelet domain L0 sparse regularization

A. Mehranian, M. R. Ay, A. Rahmim and H. Zaidi
Peer-reviewed Journal Publication
IEEE Trans Med Imaging, 2013, Vol. 32, No. 9, pp 1707-1722

160.  An Innovative Rotation-Based Iterative Resolution Recovery for HiReSPECT™: a Dedicated Small Animal SPECT System

N. Zeraatkar, M. H. Farahani, H. Arabi, S. Sarkar, S. Sajedi, N. Naderi, P. Ghafarian, A. Rahmim and M.R. Ay
Published Abstract
European Association of Nuclear Medicine Annual Congress, 27-31 October 2012, Milan, Itly. Eur J Nucl Med Mol, S386-S387

161.  Design and Development of a High Resolution Small Animal Imaging System for Mice and Rat

M.R. Ay , H. Arabi, M. H. Farahani, N. Zeraatkar, S. Sarkar, S. Sajed, N. Naderi and P. Ghafaian
Published Abstract
European Association of Nuclear Medicine Annual Congress, 27-31 October 2012, Milan, Itly. Eur J Nucl Med Mol, S441

162.  Determination of Attenuation Map at 511 keV Employing 3D Short Echo-Time MR Imaging in the Head Area: Application in MR-Based AC of PET data

P. Khareti, H. Salighe Rad, and M.R. Ay
Published Abstract
European Association of Nuclear Medicine Annual Congress, 27-31 October 2012, Milan, Itly. Eur J Nucl Med Mol, S369

163.  Digital signal processing unit for nuclear detection system

S. Sajedi, M.R. Ay, M. H. Farahani, N. Zeraatkar, H. Arabi, and N. Naderi
Published Abstract
European Association of Nuclear Medicine Annual Congress, 27-31 October 2012, Milan, Itly. Eur J Nucl Med Mol, S498

164.  Evaluation of the influence of respiratory motion misalignment between PET and CT data on diagnosis of heart defects using 4D XCAT phantom and STIR reconstruction

M. Sedighpoor, P. Ghafarian, A. Emami, M.R. Ay
Published Abstract
European Association of Nuclear Medicine Annual Congress, 27-31 October 2012, Milan, Itly. Eur J Nucl Med Mol, S515

165.  Quantification of the influence of misregistration between CT and SPECT images on the accuracy of CT-based attenuation correction of cardiac images in hybrid SPECT/CT systems

L. Saleki, A. Bitarafan-Rajabi, N. Yaghobi, B. Falahi, and M.R. Ay
Published Abstract
European Association of Nuclear Medicine Annual Congress, 27-31 October 2012, Milan, Itly. Eur J Nucl Med Mol, S518

166.  Standardized Uptake Value-Based Evaluations of Respiratory-Induced Errors in CTAC PET Images: A Simulation Study Using 4D XCAT Phantom

P. Geramifar, M. Shamsaie Zafarghandi, M.R. Ay
Published Abstract
European Association of Nuclear Medicine Annual Congress, 27-31 October 2012, Milan, Itly. Eur J Nucl Med Mol, S403

167.  SURGEOSIGHT-TM: An Intraoprative Hand Held Gamma Camera for Precise Localization of Sentine Lymph Nodes

M.R. Ay , H. Arabi, M. H. Farahani, N. Zeraatkar, S. Sarkar, S. Sajed, N. Naderi and P. Ghafaian
Published Abstract
European Association of Nuclear Medicine Annual Congress, 27-31 October 2012, Milan, Itly. Eur J Nucl Med Mol, S385

168.  The influence of crystal material and size on the performance of partial-rotating dual head small animal PET scanners: Quantitative evaluation using Monte Carlo modeling

N. Ghazanfari, M.R. Ay, S.Sarkar and G.Loudos
Published Abstract
European Association of Nuclear Medicine Annual Congress, 27-31 October 2012, Milan, Itly. Eur J Nucl Med Mol, S442

169.  The influence of resolution recovery during image reconstruction on quantitative brain SPECT imaging

A. Emami-Ardekani, F. Kalantari, H. Rajabi, M.R. Ay, A. Fard, M. Eftekhari
Published Abstract
European Association of Nuclear Medicine Annual Congress, 27-31 October 2012, Milan, Itly. Eur J Nucl Med Mol, S500

170.  Smoothly Clipped Absolute Deviation (SCAD) Regularization for Compressed Sensing MRI Using an Augmented Lagrangian Scheme

Mehranian A, H. Salighe Rad, M.R. Ay , Rahmim A, and Zaidi H
Proceeding and Conference Record
IEEE Nuclear Science Symposium & Medical Imaging Conference, Anaheim, CA, USA, 2012, pp 3646-3653

Abstract:

Compressed sensing (CS) in magnetic resonance imaging (MRI) enables the reconstruction of MR images from highly undersampled k-spaces, and thus substantial reduction of data acquisition time. In this context, edge-preserving and sparsity-promoting regularizers are used to exploit the prior knowledge that MR images are sparse or compressible in a given transform domain and thus to regulate the solution space. In this study, we introduce a new regularization scheme by iterative linearization of the non-convex clipped absolute deviation (SCAD) function in an augmented Lagrangian framework. The performance of the proposed regularization, which turned out to be an iteratively weighted total variation (TV) regularization, was evaluated using 2D phantom simulations and 3D retrospective undersampling of clinical MRI data by different sampling trajectories. It was demonstrated that the proposed regularization technique substantially outperforms conventional TV regularization, especially at reduced sampling rates.

171.  Generation of attenuation map for MR-based attenuation correction of PET data in the head area employing 3D short echo time MR imaging

P. Khareti, H. Salighe Rad, A. Fathi and M.R. Ay
Published Abstract
Proc. PSMR Conference, Isola de Elba, Italy 26-30 May , p. 70, 2012

172.  3D Calculation of Absorbed Dose for 131I Targeted Radiotherapy: A Monte Carlo Study

E. Saeedzadeh, S. Sarkar, A. Abbaspour Tehrani-Fard, M.R. Ay, H.R. Khosravi, G. Loudos
Peer-reviewed Journal Publication
Radiation Protection Dosimetry, 2012, 150, pp. 298-305

173.  3D TV-Based Compressed MR Image Reconstruction Using a Primal Dual Algorithm

A. Mehranian, H. S. Rad, M.R. Ay, and A. Rahmim
Published Abstract
Proc. Intl. Soc. Mag. Reson. Med., vol. 20, pp. 4228, 2012

174.  A novel energy mapping approach for CT-based attenuation correction in PET

B. Teimourian , M. R. Ay, M. Shamsaei-Zafarghandi, P. Ghafarian, H. Ghadiri and H. Zaidi
Peer-reviewed Journal Publication
Med Phys 2012, Vol. 39, No. 4, pp 2078-2089

175.  A proximal splitting algorithm for TV-regularized PET image reconstruction

A. Mehranian, A. Rahmim, and M.R. Ay
Published Abstract
Proc. Asia Oceania Congress of Nucl. Med. & Biology, vol. 20 (suppl. 1), p. 43, 2012

176.  An Ordered-Subsets Proximal Preconditioned Gradient Algorithm for Total Variation Regularized PET Image Reconstruction

Mehranian A, M.R. Ay, Rahmim A, and Zaidi H
Proceeding and Conference Record
IEEE Nuclear Science Symposium & Medical Imaging Conference, Anaheim, CA, USA, 2012, pp 3375-3382

177.  Development of a fully 3D image reconstruction for a pinhole animal SPECT

M. Khamesi, A. Kamali Asl, M. Masoudi, N. Zeraatkar, and M.R. Ay
Published Abstract
Proc. Asia Oceania Congress of Nucl. Med. & Biology, vol. 20 (suppl. 1), p. 122, 2012

178.  Development of image reconstruction code with collimator-detector response function compensation for a preclinical SPECT scanner

N. Zeraatkar, M. H. Farahani, H. Arabi, S. Sarkar, S. Sajedi, A. Rahmim, and M.R. Ay
Published Abstract
Proc. Asia Oceania Congress of Nucl. Med. & Biology, vol. 20 (suppl. 1), p. 36, 2012

179.  Generalized 4D AB-OSEM direct parametric imaging: application to PiB-PET

A. Rahmim, Y. Zhou, J. Price, J. Tang, L. Lu, M.R. Ay, G. Smith, V. Sossi, and D. Wong
Published Abstract
J. Nucl. Med., vol. 53 (suppl. 1): 313, 2012

180.  Generation of attenuation map for MR-based attenuation correction of PET data in the head area employing 3D short echo time MR imaging

P. Khateri, H. Saligeh Rad, A, Fathi and M.R. Ay
Peer-reviewed Journal Publication
Nuclear. Instrumentation Methods in Physics Research A, 2012, Vol. 702, No.21, pp. 133-136

181.  High resolution small animal SPECT: HiReSPECT for preclinical imaging

H. Arabi, M. H. Farahani, N. Zeraatkar, S. Sarkar, S. Sajedi, A. Rahmim, P. Ghafarian and M.R. Ay
Published Abstract
Proc. Asia Oceania Congress of Nucl. Med. & Biology, vol. 20 (suppl. 1), p. 93, 2012

182.  HiReSPECT an in house high resolution SPECT imaging system

M.R. Ay
Published Abstract
Proc. Asia Oceania Congress of Nucl. Med. & Biology, vol. 20 (suppl. 1), p. 10, 2012

183.  Impact of miscentering on patient dose and image noise in x-ray CT imaging: Phantom and clinical studies

M.A. Habibzadeh, M.R. Ay, A.R. Kamali Asl, H. Ghadiri and H. Zaidi H
Peer-reviewed Journal Publication
Phys Med Vol. 28, 2012, pp. 191-199

184.  Implementation of data acquisition board with digital signal processing capability for nuclear imaging and spectrometry devices

S. Sajedi, M. H. Farahani, H. Arabi, N. Zeraatkar, and M.R. Ay
Published Abstract
Proc. Asia Oceania Congress of Nucl. Med. & Biology, vol. 20 (suppl. 1), p. 39, 2012

185.  QCT technique optimization by dual energy CT

A. Emami, H. Ghadiri, P. Ghafarian and M.R. Ay
Published Abstract
Proc. Asia Oceania Congress of Nucl. Med. & Biology, vol. 20 (suppl. 1), p. 125, 2012

186.  Quantification of the influence of respiratory motion induced misalignment between PET and CT data on diagnosis of heart disease in cardiac PET/CT imaging

M. Sedigpoor, M.R. Ay, P. Ghafarian, P. Farnia
Published Abstract
Proc. Asia Oceania Congress of Nucl. Med. & Biology, vol. 20 (suppl. 1), p. 129, 2012

187.  Quantitative assessment of the influence of crystal material and size on the performance of rotating dual head small animal PET scanners: Monte Carlo modeling

N. Ghazanfari, S. Sarkar, G. Loudos, M.R. Ay
Peer-reviewed Journal Publication
Hellenic Journal of Nuclear Medicine, 2012, Vol. 15, No. 1, pp. 33-39

188.  The accuracy of dual energy mapping approach in CTAC in presence of low concentration of contract agent

H. Ghadiri, M.B. Shiran, H. Zaidi, H. Soltanian Zadeh and M.R. Ay
Published Abstract
Proc. Asia Oceania Congress of Nucl. Med. & Biology, vol. 20 (suppl. 1), p. 60, 2012

189.  The influence of opening angels and collimator material on the spatial resolution of pinhole collimator in animal SPECT imaging

M. Masoudi, A. Kamali Asl, M. Khamesi, H. Arabi and M.R. Ay
Published Abstract
Proc. Asia Oceania Congress of Nucl. Med. & Biology, vol. 20 (suppl. 1), p. 122, 2012

190.  The infuence of resolution recovery by using collimator detector response during 3D OSEM image reconstruction on 99mTc-ECD brain SPET images

F. Kalantari, H. Rajabi, M. R. Ay, A. Fard Esfahani, M. Eftekhari, B. Fallahi, A. Emami Ardekani
Peer-reviewed Journal Publication <