Farhad Daghighian - Academia.edu (original) (raw)
Papers by Farhad Daghighian
Journal of Neuro-Oncology, 1994
Journal of Nuclear Medicine, 1994
Iodine-131-iododeoxyuridine (IUdR) uptake and retention was imaged with SPECT at 2 and 24 hr afte... more Iodine-131-iododeoxyuridine (IUdR) uptake and retention was imaged with SPECT at 2 and 24 hr after administering a 10-mCi dose to six patients with primary brain tumors. The SPECT images were directly compared to gadolinium contrast-enhanced MR images as well as to (¹â¸F) fluorodeoxyglucose (FDG) PET scans and ²°¹Tl SPECT scans. Localized uptake and retention of IUdR-derived radioactivity was observed in
Proceedings of 1994 IEEE Nuclear Science Symposium - NSS'94, 1995
Various parameters relevant to the design of a small scale PET scanner were studied both experime... more Various parameters relevant to the design of a small scale PET scanner were studied both experimentally and by computer simulation. LSO (cerium-doped lutetium oxyorthosilicate) was compared with EGO, using a position sensitive PMT (PSPMT). (Compared to EGO, LSO has 8 times faster decay time, 4 times the scintillation light output, but 14% lower attenuation coefficient for 511 keV photons). The experiments with EGO and LSO involved: the crystal identification on the face of a PSPMT, measurement of the coincidence line-spread functions, and measurement of the sensitivity above the electronic noise. The resulting coincidence images clearly resolved each LSO crystal. EGS4 Monte Carlo simulations were used to estimate the efficiency, singles rate and mispositioning due to the depth of interaction for PET scanners with various sizes of LSO and EGO
In this work we develop a relativistic formalism for calculating the radiative transition rates o... more In this work we develop a relativistic formalism for calculating the radiative transition rates of a fermion -antifermion bound state. We calculate the radiative decay rates in charmonium and b-quarkonium systems and find them generally in better agreement with experiment than other previous works, in particular for the case of hindered magnetic transition of psi^' . Our relativistic formalism automatically includes the effect of the recoil of the final bound state or, equivalently, a sum over all multipoles, which is important in mesonic radiative transitions. It also treats both quark and antiquark as four component spinors to give relativistic currents, and includes a natural mixing of L-S terms for a given J and parity. We discover the importance of systematic inclusion of these relativistic effects by comparing our relativistic result with a nonrelativistic calculation. The bound state equation and interactions that were used was based on the formalism that was developed by...
Medical Physics
An intraoperative beta probe was designed, built, and tested for detection of radio-labeled malig... more An intraoperative beta probe was designed, built, and tested for detection of radio-labeled malignant tissues that has the advantage of being selectively sensitive to beta while insensitive to gamma radiation. Since beta radiation (electrons or positrons) has a short range in tissue, this probe is ideal for detecting tracers in tumors at the surface of the surgical field. This probe contains a plastic scintillation detector sensitive to beta rays and to a lesser degree some background gamma rays. A second detector counts spurious gamma rays and allows for their subtraction from the activity measured by the first detector. Sensitivity of the dual probe for I-131 and F-18 was measured to be 108 counts/s/kBq (4000 counts/s/microCi). The dual-detector probe faithfully measured the 10:1 "tumor" to background ratio of radioactivity concentrations in a simulated environment of a tumor in the presence of intense background 511 keV photons. In another phantom experiment, simulating...
Journal of Nuclear Medicine Technology
This is the first article of a four-part series on positron emission tomography (PET). Upon compl... more This is the first article of a four-part series on positron emission tomography (PET). Upon completing the article, the reader should be able to: (1) comprehend the basic principles of PET; (2) explain various technical aspects; and (3) identify radiopharmaceuticals used in PET imaging.
Journal of Nuclear Medicine
The thymidine analog, 5-iodo-2â²-deoxyuridine (IUdR), is incorporated in the DNA of cell sin the ... more The thymidine analog, 5-iodo-2â²-deoxyuridine (IUdR), is incorporated in the DNA of cell sin the S phase. When incorporated in the DNA, short-range Auger electrons emitted by ¹²âµI-labeled IUdR can cause double-strand breaks, delivering a lethal radiation dose to the cell. We conducted therapeutic trial to evaluate [¹²âµI/¹³¹I]IUdR pharmacokinetics in liver metastases from colorectal cancer. Dosimetry, safety, and therapeutic potential were assessed. Four patients were each infused with 5 mCi [¹²âµI]IUdR and 10 mCi [¹³¹I]IUdR through the sideport of a hepatic artery pump. Iodine-131 images were quantitated and used for pharmacokinetic studies. The radioactivity in the DNA of biopsy samples of tumor, normal liver and bone marrow, obtained 24 or 48 hr after injection, was counted. All patients had [¹²âµI]IUdR and [¹³¹I]IUdR uptake in tumor, with a biexponential clearance. Repeat injections in individual patients showed little variation in tumor uptake, especially ...
Journal of Nuclear Medicine
The radiotoxicity of 125I is highly sensitive to the site of decay relative to nuclear DNA. This ... more The radiotoxicity of 125I is highly sensitive to the site of decay relative to nuclear DNA. This paper describes a new approach, based upon pharmacokinetic clearance of radioactivity from the tumor, with which to quantify the fraction of [125I]IUdR incorporated within the DNA of tumor cells. Patients were injected with [125I]IUdR through the hepatic artery. Iodine-131-IUdR was used as a tracer for imaging and quantitation. Both conventional and DNA-level dosimetry were performed. We calculated that if 15% of the tumor cells were in S phase at the time of injection, there would be 250 decays of 125I in the DNA per tumor cell after an infusion of 5 mCi [125I]IUdR. According to in vitro data based on 5 x 10(8) cells per g tumor, 99% of these cells in S phase would be killed. The estimate of cell inactivation is strongly dependent on the number of cells per gram and the fraction of cells in S phase at the time of injection, which indicates that repeat injections would be necessary to ac...
Journal of Nuclear Medicine
The thymidine analog, 5-iodo-2'-deoxyuridine (IUdR), is incorporated in the DNA of cells in t... more The thymidine analog, 5-iodo-2'-deoxyuridine (IUdR), is incorporated in the DNA of cells in the S phase. When incorporated into DNA, short-range Auger electrons emitted by 125I-labeled IUdR can cause double-strand breaks, delivering a lethal radiation dose to the cell. We conducted therapeutic trial to evaluate[125I/131I]IUdR pharmacokinetics in liver metastases from colorectal cancer. Dosimetry, safety, and therapeutic potential were assessed. Four patients were each infused with 5 mCi [125I]IUdR and 10 mCi [131I]IUdR through the sideport of a hepatic artery pump. Iodine-131 images were quantitated and used for pharmacokinetic studies. The radioactivity in the DNA of biopsy samples of tumor, normal liver and bone marrow, obtained 24 or 48 hr after injection, was counted. All patients had [125I]IUdR and [131I]IUdR uptake in tumor, with a biexponential clearance. Repeat injections in individual patients showed little variation in tumor uptake, especially in the slow clearance com...
The hypothesis of this project is that these novel cameras, applied during surgery on prostate ca... more The hypothesis of this project is that these novel cameras, applied during surgery on prostate cancer patients after being injected by radio labeled antibody J591, would detect small pieces of cancerous tissue that would otherwise remain undetected. According to our project, a group of prostate cancer patients who are scheduled for surgery, will be injected with radio labeled J591 mAb. Then our cameras will be used during surgery to locate any involved lymph node, or tissues at the margins of the resected prostate that may be infiltrated by cancer Also, we planned to use our flexible beta camera to locate the best site in transrectal biopsies using Y-90 - labeled mAb. According to our plan, the first year was devoted to development of the novel instrumentation for detection of prostate tumors. This task was successfully completed. The next eighteen months was devoted to testing and characterizing the devices in laboratory and improving them as needed. This task was also successfully...
2006 IEEE Nuclear Science Symposium Conference Record, 2006
We have developed a working prototype of a beta camera based on solid state photomultipliers (SSP... more We have developed a working prototype of a beta camera based on solid state photomultipliers (SSPMs), to demonstrate proof of concept. The SSPM, essentially an array of avalanche photodiodes operating in Geiger mode, produces a gain equal to or better than that of a photomultiplier tube, while operating at low bias voltage. The beta camera consists of a sheet of red-emitting plastic scintillator coupled to a 4 times 4 array of SSPMs. The signals are multiplexed through a 4-channel readout board and digitized by a custom data acquisition program; the image is constructed via simple Anger logic. We have obtained a positron energy spectrum and initial images from the camera, as well as linearity data and spatial resolution measurements.
2008 IEEE Nuclear Science Symposium Conference Record, 2008
ABSTRACT Silicon photomultipliers (SiPMs) have shown great promise as photodetectors in detecting... more ABSTRACT Silicon photomultipliers (SiPMs) have shown great promise as photodetectors in detecting scintillation light from gamma and beta rays, and are currently being investigated for use in imaging. Most studies have been done with single sensors for gamma detection. We have built linear and two dimensional arrays of SiPMs and evaluated them for suitability in beta imaging. Both arrays employ 1 mm × 1 mm Multi Pixel Photon Counters (MPPCs). The first array is a 1 × 4 array with 2.5 mm pixel pitch. The second is a 5 × 5 array with 3 mm pitch. For both arrays we acquired energy spectra for annihilation photons with LYSO scintillators, and for positrons from F-18 and Tl-204 with blue plastic scintillator. We imaged collimated F-18 beta sources, and measured the spatial resolution and sensitivity. For the linear array, the spatial resolution is 2.6 mm at the center of the array, and the sensitivity is 0.27 cps/Bq. For the 5 × 5 array, the spatial resolution is 2.1 mm at the center of the array, and the sensitivity is 0.36 cps/Bq.
2008 IEEE Nuclear Science Symposium Conference Record, 2008
ABSTRACT The aim of this study is to develop and test a prototype miniature gamma spectrometer ba... more ABSTRACT The aim of this study is to develop and test a prototype miniature gamma spectrometer based on silicon photomultipliers (SiPMs). Such a device could potentially be made small and inexpensive enough to be essentially disposable, allowing the deployment of thousands of radiation detection units in remote areas where manned surveillance is unfeasible. In this work we investigate only the spectroscopy performance of silicon photomultipliers at room temperature, and do not consider issues of data transmission, protection from the elements, etc. Two such devices have been built and tested. The first consists of two 2 × 2 arrays of 3 mm × 3 mm SiPMs from Photonique, mounted on opposite faces of a 1 cm × 1 cm × 1 cm CsI(Tl) crystal. Using 8 SiPMs is intended to improve light collection from the scintillator as well as to expand the dynamic range by increasing the number of microcells. The four signals from each side are summed and acquired in coincidence mode - while multiplying the number of SiPMs increases the total electronic noise, we investigate whether using coincidence gating could ultimately reduce noise and allow detection of low energy photons. The second spectrometer consists of two 3 mm × 3 mm SiPMs from Hamamatsu coupled to opposite faces of a 4 mm × 4 mm × 10 mm LYSO crystal. The two signals are also acquired in coincidence. The gated spectra are compared to non-gated, background-subtracted summed spectra to evaluate the usefulness of coincidence for noise reduction. For both setups, we obtain gamma spectra for five different isotopes (Na-22, Cs-137, U-238 (as depleted uranium, or DU), Co-57, Ba-133, and also F-18 and Tc-99m for the Hamamatsu devices). For comparison, spectra for these sources are also acquired using the same scintillators on a PMT. Again, all spectra are acquired at room temperature.
Journal of clinical oncology : official journal of the American Society of Clinical Oncology, 1996
A phase I/II study was designed to determine the maximum-tolerated dose (MTD) of iodine 125-label... more A phase I/II study was designed to determine the maximum-tolerated dose (MTD) of iodine 125-labeled monoclonal antibody A33 (125I-mAb A33), its limiting organ toxicity, and the uptake and retention of radioactivity in tumor lesions. Patients (N = 21) with advanced chemotherapy-resistant colon cancer who had not received prior radiotherapy were treated with a single 125I-mAb A33 dose. 125I doses were escalated from 50 to 350 mCi/m2 in 50-mCi/m2 increments. Radioimmunoscintigrams were performed for up to 6 weeks after 125I-mAb A33 administration. All 20 patients with radiologic evidence of disease showed localization of 125I to sites of disease. Twelve of 14 patients, who underwent imaging studies 4 to 6 weeks after antibody administration, had sufficient isotope retention in tumor lesions to make external imaging possible. No major toxicity was observed, except in one patient with prior exposure to mitomycin who developed transient grade 3 thrombocytopenia. Although the isotope showe...
Clinical cancer research : an official journal of the American Association for Cancer Research, 1999
Rhenium-186 (tin)-labeled hydroxyethylidene diphosphonate (186Re-labeled HEDP) was evaluated in 2... more Rhenium-186 (tin)-labeled hydroxyethylidene diphosphonate (186Re-labeled HEDP) was evaluated in 27 men with progressive androgen-independent prostate cancer and bone metastases. Administered activities ranged from 1251 to 4336 MBq (33.8-117.2 mCi). The primary objectives were to assess tumor targeting, normal organ dosimetry, and safety. Antitumor effects were assessed by posttherapy changes in prostate-specific antigen and, when present, palliation of pain. Whole-body kinetics, blood and kidney clearance, skeletal dose, marrow dose, and urinary excretion of the isotope were assessed. Targeting of skeletal disease was observed over the period of quantification (4-168 h). Radiation doses to whole body, bladder, and kidney were well tolerated. The dose-limiting toxicity was myelosuppression (grade III) at 4107 MBq (111 mCi) and grade II at 296 MBq (80 mCi). Probe clearance (whole body) and urinary excretion measurements were highly correlated. Of the six patients treated at the highes...
Cancer research, 1998
We report a series of studies that assess the feasibility and sensitivity of imaging of herpes vi... more We report a series of studies that assess the feasibility and sensitivity of imaging of herpes virus type one thymidine kinase (HSV1-tk) gene transfer and expression with [124I]-5-iodo-2'-fluoro-1-beta-D-arabinofuranosyluracil ([124I]-FIAU) and positron emission tomography (PET) and the ability of [124I]-FIAU-PET imaging to discriminate different levels of HSV1-tk gene expression. Studies were performed in rats bearing multiple s.c. tumors derived from W256 rat carcinoma and RG2 rat glioma cells. In the first set, we tested the sensitivity of [124I]-FIAU-PET imaging to detect low levels of HSV1-tk gene expression after retroviral-mediated gene transfer. HSV1-tk gene transduction of one of preestablished wild-type W256 tumor in each animal was accomplished by direct intratumoral injection of retroviral vector-producer cells (W256-->W256TK* tumors). Tumors produced from W256 and W256TK+ cells served as the negative and positive control in each animal. Highly specific images of ...
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1996
PET is potentially very useful for the accurate in vivo quantitation of time-varying biological d... more PET is potentially very useful for the accurate in vivo quantitation of time-varying biological distributions of radiolabeled antibodies over several days. The short half-lives of most commonly used positron-emitting nuclides make them unsuitable for this purpose. Iodine-124 is a positron emitter with a half-life of 4.2 days and appropriate chemical properties. It has not been widely used because of a complex decay scheme including several high energy gamma rays. However, measurements made under realistic conditions on several different PET scanners have shown that satisfactory imaging and quantitation can be achieved. Whole-body and head-optimized scanners with different detectors (discrete BGO, block BGO and BaF2 time-of-flight), different septa and different correction schemes were used. Measurements of resolution, quantitative linearity and the ability to quantitatively image spheres of different sizes and activities in different background activities were made using phantoms. C...
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1996
In radioimmunotherapy, the emission characteristics of the radioisotope is critical in determinin... more In radioimmunotherapy, the emission characteristics of the radioisotope is critical in determining the radiation dose to the tumor compared to normal organs. If antibodies internalize and transport low-energy electron emitting isotopes close to the tumor cell nucleus, an improved therapeutic advantage is achieved. Using fluorescent microscopy, we studied the subcellular distribution of an internalizing antibody, A33, which detects a restricted determinant on colon cancer cells. We developed a physical model to assess the dose deposited on the nucleus by electrons emitted from radiolabeled A33 accumulated inside vesicles. This model is based on the energy-range relationship of electrons in water. Similarly, another model was developed to calculate the radiation dose to the nucleus from electrons emitted from extracellular space. The percentage of A33 bound to membrane and internalized was determined in vitro at various time points. Cytotoxicity experiments were performed with 125I- a...
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1994
Iodine-131-iododeoxyuridine (IUdR) uptake and retention was imaged with SPECT at 2 and 24 hr afte... more Iodine-131-iododeoxyuridine (IUdR) uptake and retention was imaged with SPECT at 2 and 24 hr after administering a 10-mCi dose to six patients with primary brain tumors. The SPECT images were directly compared to gadolinium contrast-enhanced MR images as well as to [18F]fluorodeoxyglucose (FDG) PET scans and 201Tl SPECT scans. Localized uptake and retention of IUdR-derived radioactivity was observed in five of six patients. The plasma half-life of [131I]IUdR was short (1.6 min) in comparison to the half-life of total plasma radioactivity (6.4 hr). The pattern of [131I]IUdR-derived radioactivity was markedly different in the 2-hr compared to 24-hr images. Radioactivity was localized along the periphery of the tumor and extended beyond the margin of tumor identified by contrast enhancement on MRI. The estimated levels of tumor radioactivity at 24 hr, based on semiquantitative phantom studies, ranged between < 0.1 and 0.2 microCi/cc (< 0.001% and 0.002% dose/cc); brain levels wer...
Journal of Neuro-Oncology, 1994
Journal of Nuclear Medicine, 1994
Iodine-131-iododeoxyuridine (IUdR) uptake and retention was imaged with SPECT at 2 and 24 hr afte... more Iodine-131-iododeoxyuridine (IUdR) uptake and retention was imaged with SPECT at 2 and 24 hr after administering a 10-mCi dose to six patients with primary brain tumors. The SPECT images were directly compared to gadolinium contrast-enhanced MR images as well as to (¹â¸F) fluorodeoxyglucose (FDG) PET scans and ²°¹Tl SPECT scans. Localized uptake and retention of IUdR-derived radioactivity was observed in
Proceedings of 1994 IEEE Nuclear Science Symposium - NSS'94, 1995
Various parameters relevant to the design of a small scale PET scanner were studied both experime... more Various parameters relevant to the design of a small scale PET scanner were studied both experimentally and by computer simulation. LSO (cerium-doped lutetium oxyorthosilicate) was compared with EGO, using a position sensitive PMT (PSPMT). (Compared to EGO, LSO has 8 times faster decay time, 4 times the scintillation light output, but 14% lower attenuation coefficient for 511 keV photons). The experiments with EGO and LSO involved: the crystal identification on the face of a PSPMT, measurement of the coincidence line-spread functions, and measurement of the sensitivity above the electronic noise. The resulting coincidence images clearly resolved each LSO crystal. EGS4 Monte Carlo simulations were used to estimate the efficiency, singles rate and mispositioning due to the depth of interaction for PET scanners with various sizes of LSO and EGO
In this work we develop a relativistic formalism for calculating the radiative transition rates o... more In this work we develop a relativistic formalism for calculating the radiative transition rates of a fermion -antifermion bound state. We calculate the radiative decay rates in charmonium and b-quarkonium systems and find them generally in better agreement with experiment than other previous works, in particular for the case of hindered magnetic transition of psi^' . Our relativistic formalism automatically includes the effect of the recoil of the final bound state or, equivalently, a sum over all multipoles, which is important in mesonic radiative transitions. It also treats both quark and antiquark as four component spinors to give relativistic currents, and includes a natural mixing of L-S terms for a given J and parity. We discover the importance of systematic inclusion of these relativistic effects by comparing our relativistic result with a nonrelativistic calculation. The bound state equation and interactions that were used was based on the formalism that was developed by...
Medical Physics
An intraoperative beta probe was designed, built, and tested for detection of radio-labeled malig... more An intraoperative beta probe was designed, built, and tested for detection of radio-labeled malignant tissues that has the advantage of being selectively sensitive to beta while insensitive to gamma radiation. Since beta radiation (electrons or positrons) has a short range in tissue, this probe is ideal for detecting tracers in tumors at the surface of the surgical field. This probe contains a plastic scintillation detector sensitive to beta rays and to a lesser degree some background gamma rays. A second detector counts spurious gamma rays and allows for their subtraction from the activity measured by the first detector. Sensitivity of the dual probe for I-131 and F-18 was measured to be 108 counts/s/kBq (4000 counts/s/microCi). The dual-detector probe faithfully measured the 10:1 "tumor" to background ratio of radioactivity concentrations in a simulated environment of a tumor in the presence of intense background 511 keV photons. In another phantom experiment, simulating...
Journal of Nuclear Medicine Technology
This is the first article of a four-part series on positron emission tomography (PET). Upon compl... more This is the first article of a four-part series on positron emission tomography (PET). Upon completing the article, the reader should be able to: (1) comprehend the basic principles of PET; (2) explain various technical aspects; and (3) identify radiopharmaceuticals used in PET imaging.
Journal of Nuclear Medicine
The thymidine analog, 5-iodo-2â²-deoxyuridine (IUdR), is incorporated in the DNA of cell sin the ... more The thymidine analog, 5-iodo-2â²-deoxyuridine (IUdR), is incorporated in the DNA of cell sin the S phase. When incorporated in the DNA, short-range Auger electrons emitted by ¹²âµI-labeled IUdR can cause double-strand breaks, delivering a lethal radiation dose to the cell. We conducted therapeutic trial to evaluate [¹²âµI/¹³¹I]IUdR pharmacokinetics in liver metastases from colorectal cancer. Dosimetry, safety, and therapeutic potential were assessed. Four patients were each infused with 5 mCi [¹²âµI]IUdR and 10 mCi [¹³¹I]IUdR through the sideport of a hepatic artery pump. Iodine-131 images were quantitated and used for pharmacokinetic studies. The radioactivity in the DNA of biopsy samples of tumor, normal liver and bone marrow, obtained 24 or 48 hr after injection, was counted. All patients had [¹²âµI]IUdR and [¹³¹I]IUdR uptake in tumor, with a biexponential clearance. Repeat injections in individual patients showed little variation in tumor uptake, especially ...
Journal of Nuclear Medicine
The radiotoxicity of 125I is highly sensitive to the site of decay relative to nuclear DNA. This ... more The radiotoxicity of 125I is highly sensitive to the site of decay relative to nuclear DNA. This paper describes a new approach, based upon pharmacokinetic clearance of radioactivity from the tumor, with which to quantify the fraction of [125I]IUdR incorporated within the DNA of tumor cells. Patients were injected with [125I]IUdR through the hepatic artery. Iodine-131-IUdR was used as a tracer for imaging and quantitation. Both conventional and DNA-level dosimetry were performed. We calculated that if 15% of the tumor cells were in S phase at the time of injection, there would be 250 decays of 125I in the DNA per tumor cell after an infusion of 5 mCi [125I]IUdR. According to in vitro data based on 5 x 10(8) cells per g tumor, 99% of these cells in S phase would be killed. The estimate of cell inactivation is strongly dependent on the number of cells per gram and the fraction of cells in S phase at the time of injection, which indicates that repeat injections would be necessary to ac...
Journal of Nuclear Medicine
The thymidine analog, 5-iodo-2'-deoxyuridine (IUdR), is incorporated in the DNA of cells in t... more The thymidine analog, 5-iodo-2'-deoxyuridine (IUdR), is incorporated in the DNA of cells in the S phase. When incorporated into DNA, short-range Auger electrons emitted by 125I-labeled IUdR can cause double-strand breaks, delivering a lethal radiation dose to the cell. We conducted therapeutic trial to evaluate[125I/131I]IUdR pharmacokinetics in liver metastases from colorectal cancer. Dosimetry, safety, and therapeutic potential were assessed. Four patients were each infused with 5 mCi [125I]IUdR and 10 mCi [131I]IUdR through the sideport of a hepatic artery pump. Iodine-131 images were quantitated and used for pharmacokinetic studies. The radioactivity in the DNA of biopsy samples of tumor, normal liver and bone marrow, obtained 24 or 48 hr after injection, was counted. All patients had [125I]IUdR and [131I]IUdR uptake in tumor, with a biexponential clearance. Repeat injections in individual patients showed little variation in tumor uptake, especially in the slow clearance com...
The hypothesis of this project is that these novel cameras, applied during surgery on prostate ca... more The hypothesis of this project is that these novel cameras, applied during surgery on prostate cancer patients after being injected by radio labeled antibody J591, would detect small pieces of cancerous tissue that would otherwise remain undetected. According to our project, a group of prostate cancer patients who are scheduled for surgery, will be injected with radio labeled J591 mAb. Then our cameras will be used during surgery to locate any involved lymph node, or tissues at the margins of the resected prostate that may be infiltrated by cancer Also, we planned to use our flexible beta camera to locate the best site in transrectal biopsies using Y-90 - labeled mAb. According to our plan, the first year was devoted to development of the novel instrumentation for detection of prostate tumors. This task was successfully completed. The next eighteen months was devoted to testing and characterizing the devices in laboratory and improving them as needed. This task was also successfully...
2006 IEEE Nuclear Science Symposium Conference Record, 2006
We have developed a working prototype of a beta camera based on solid state photomultipliers (SSP... more We have developed a working prototype of a beta camera based on solid state photomultipliers (SSPMs), to demonstrate proof of concept. The SSPM, essentially an array of avalanche photodiodes operating in Geiger mode, produces a gain equal to or better than that of a photomultiplier tube, while operating at low bias voltage. The beta camera consists of a sheet of red-emitting plastic scintillator coupled to a 4 times 4 array of SSPMs. The signals are multiplexed through a 4-channel readout board and digitized by a custom data acquisition program; the image is constructed via simple Anger logic. We have obtained a positron energy spectrum and initial images from the camera, as well as linearity data and spatial resolution measurements.
2008 IEEE Nuclear Science Symposium Conference Record, 2008
ABSTRACT Silicon photomultipliers (SiPMs) have shown great promise as photodetectors in detecting... more ABSTRACT Silicon photomultipliers (SiPMs) have shown great promise as photodetectors in detecting scintillation light from gamma and beta rays, and are currently being investigated for use in imaging. Most studies have been done with single sensors for gamma detection. We have built linear and two dimensional arrays of SiPMs and evaluated them for suitability in beta imaging. Both arrays employ 1 mm × 1 mm Multi Pixel Photon Counters (MPPCs). The first array is a 1 × 4 array with 2.5 mm pixel pitch. The second is a 5 × 5 array with 3 mm pitch. For both arrays we acquired energy spectra for annihilation photons with LYSO scintillators, and for positrons from F-18 and Tl-204 with blue plastic scintillator. We imaged collimated F-18 beta sources, and measured the spatial resolution and sensitivity. For the linear array, the spatial resolution is 2.6 mm at the center of the array, and the sensitivity is 0.27 cps/Bq. For the 5 × 5 array, the spatial resolution is 2.1 mm at the center of the array, and the sensitivity is 0.36 cps/Bq.
2008 IEEE Nuclear Science Symposium Conference Record, 2008
ABSTRACT The aim of this study is to develop and test a prototype miniature gamma spectrometer ba... more ABSTRACT The aim of this study is to develop and test a prototype miniature gamma spectrometer based on silicon photomultipliers (SiPMs). Such a device could potentially be made small and inexpensive enough to be essentially disposable, allowing the deployment of thousands of radiation detection units in remote areas where manned surveillance is unfeasible. In this work we investigate only the spectroscopy performance of silicon photomultipliers at room temperature, and do not consider issues of data transmission, protection from the elements, etc. Two such devices have been built and tested. The first consists of two 2 × 2 arrays of 3 mm × 3 mm SiPMs from Photonique, mounted on opposite faces of a 1 cm × 1 cm × 1 cm CsI(Tl) crystal. Using 8 SiPMs is intended to improve light collection from the scintillator as well as to expand the dynamic range by increasing the number of microcells. The four signals from each side are summed and acquired in coincidence mode - while multiplying the number of SiPMs increases the total electronic noise, we investigate whether using coincidence gating could ultimately reduce noise and allow detection of low energy photons. The second spectrometer consists of two 3 mm × 3 mm SiPMs from Hamamatsu coupled to opposite faces of a 4 mm × 4 mm × 10 mm LYSO crystal. The two signals are also acquired in coincidence. The gated spectra are compared to non-gated, background-subtracted summed spectra to evaluate the usefulness of coincidence for noise reduction. For both setups, we obtain gamma spectra for five different isotopes (Na-22, Cs-137, U-238 (as depleted uranium, or DU), Co-57, Ba-133, and also F-18 and Tc-99m for the Hamamatsu devices). For comparison, spectra for these sources are also acquired using the same scintillators on a PMT. Again, all spectra are acquired at room temperature.
Journal of clinical oncology : official journal of the American Society of Clinical Oncology, 1996
A phase I/II study was designed to determine the maximum-tolerated dose (MTD) of iodine 125-label... more A phase I/II study was designed to determine the maximum-tolerated dose (MTD) of iodine 125-labeled monoclonal antibody A33 (125I-mAb A33), its limiting organ toxicity, and the uptake and retention of radioactivity in tumor lesions. Patients (N = 21) with advanced chemotherapy-resistant colon cancer who had not received prior radiotherapy were treated with a single 125I-mAb A33 dose. 125I doses were escalated from 50 to 350 mCi/m2 in 50-mCi/m2 increments. Radioimmunoscintigrams were performed for up to 6 weeks after 125I-mAb A33 administration. All 20 patients with radiologic evidence of disease showed localization of 125I to sites of disease. Twelve of 14 patients, who underwent imaging studies 4 to 6 weeks after antibody administration, had sufficient isotope retention in tumor lesions to make external imaging possible. No major toxicity was observed, except in one patient with prior exposure to mitomycin who developed transient grade 3 thrombocytopenia. Although the isotope showe...
Clinical cancer research : an official journal of the American Association for Cancer Research, 1999
Rhenium-186 (tin)-labeled hydroxyethylidene diphosphonate (186Re-labeled HEDP) was evaluated in 2... more Rhenium-186 (tin)-labeled hydroxyethylidene diphosphonate (186Re-labeled HEDP) was evaluated in 27 men with progressive androgen-independent prostate cancer and bone metastases. Administered activities ranged from 1251 to 4336 MBq (33.8-117.2 mCi). The primary objectives were to assess tumor targeting, normal organ dosimetry, and safety. Antitumor effects were assessed by posttherapy changes in prostate-specific antigen and, when present, palliation of pain. Whole-body kinetics, blood and kidney clearance, skeletal dose, marrow dose, and urinary excretion of the isotope were assessed. Targeting of skeletal disease was observed over the period of quantification (4-168 h). Radiation doses to whole body, bladder, and kidney were well tolerated. The dose-limiting toxicity was myelosuppression (grade III) at 4107 MBq (111 mCi) and grade II at 296 MBq (80 mCi). Probe clearance (whole body) and urinary excretion measurements were highly correlated. Of the six patients treated at the highes...
Cancer research, 1998
We report a series of studies that assess the feasibility and sensitivity of imaging of herpes vi... more We report a series of studies that assess the feasibility and sensitivity of imaging of herpes virus type one thymidine kinase (HSV1-tk) gene transfer and expression with [124I]-5-iodo-2'-fluoro-1-beta-D-arabinofuranosyluracil ([124I]-FIAU) and positron emission tomography (PET) and the ability of [124I]-FIAU-PET imaging to discriminate different levels of HSV1-tk gene expression. Studies were performed in rats bearing multiple s.c. tumors derived from W256 rat carcinoma and RG2 rat glioma cells. In the first set, we tested the sensitivity of [124I]-FIAU-PET imaging to detect low levels of HSV1-tk gene expression after retroviral-mediated gene transfer. HSV1-tk gene transduction of one of preestablished wild-type W256 tumor in each animal was accomplished by direct intratumoral injection of retroviral vector-producer cells (W256-->W256TK* tumors). Tumors produced from W256 and W256TK+ cells served as the negative and positive control in each animal. Highly specific images of ...
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1996
PET is potentially very useful for the accurate in vivo quantitation of time-varying biological d... more PET is potentially very useful for the accurate in vivo quantitation of time-varying biological distributions of radiolabeled antibodies over several days. The short half-lives of most commonly used positron-emitting nuclides make them unsuitable for this purpose. Iodine-124 is a positron emitter with a half-life of 4.2 days and appropriate chemical properties. It has not been widely used because of a complex decay scheme including several high energy gamma rays. However, measurements made under realistic conditions on several different PET scanners have shown that satisfactory imaging and quantitation can be achieved. Whole-body and head-optimized scanners with different detectors (discrete BGO, block BGO and BaF2 time-of-flight), different septa and different correction schemes were used. Measurements of resolution, quantitative linearity and the ability to quantitatively image spheres of different sizes and activities in different background activities were made using phantoms. C...
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1996
In radioimmunotherapy, the emission characteristics of the radioisotope is critical in determinin... more In radioimmunotherapy, the emission characteristics of the radioisotope is critical in determining the radiation dose to the tumor compared to normal organs. If antibodies internalize and transport low-energy electron emitting isotopes close to the tumor cell nucleus, an improved therapeutic advantage is achieved. Using fluorescent microscopy, we studied the subcellular distribution of an internalizing antibody, A33, which detects a restricted determinant on colon cancer cells. We developed a physical model to assess the dose deposited on the nucleus by electrons emitted from radiolabeled A33 accumulated inside vesicles. This model is based on the energy-range relationship of electrons in water. Similarly, another model was developed to calculate the radiation dose to the nucleus from electrons emitted from extracellular space. The percentage of A33 bound to membrane and internalized was determined in vitro at various time points. Cytotoxicity experiments were performed with 125I- a...
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1994
Iodine-131-iododeoxyuridine (IUdR) uptake and retention was imaged with SPECT at 2 and 24 hr afte... more Iodine-131-iododeoxyuridine (IUdR) uptake and retention was imaged with SPECT at 2 and 24 hr after administering a 10-mCi dose to six patients with primary brain tumors. The SPECT images were directly compared to gadolinium contrast-enhanced MR images as well as to [18F]fluorodeoxyglucose (FDG) PET scans and 201Tl SPECT scans. Localized uptake and retention of IUdR-derived radioactivity was observed in five of six patients. The plasma half-life of [131I]IUdR was short (1.6 min) in comparison to the half-life of total plasma radioactivity (6.4 hr). The pattern of [131I]IUdR-derived radioactivity was markedly different in the 2-hr compared to 24-hr images. Radioactivity was localized along the periphery of the tumor and extended beyond the margin of tumor identified by contrast enhancement on MRI. The estimated levels of tumor radioactivity at 24 hr, based on semiquantitative phantom studies, ranged between < 0.1 and 0.2 microCi/cc (< 0.001% and 0.002% dose/cc); brain levels wer...