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Annals of Nuclear Medicine Apr 2015In proton therapy, imaging of proton-induced positrons is a useful method to monitor the proton beam distribution after therapy. Usually, a positron emission tomography...
PURPOSE
In proton therapy, imaging of proton-induced positrons is a useful method to monitor the proton beam distribution after therapy. Usually, a positron emission tomography (PET) system installed in or near the proton beam treatment room is used for this purpose. However, a PET system is sometimes too large and expensive for this purpose. We developed a small field-of-view (FOV) gamma camera for high-energy gamma photons and used it for monitoring the proton-induced positron distribution.
METHODS
The gamma camera used 0.85 mm × 0.85 mm × 10 mm Ce:Gd3Al2Ga3O12 (GAGG) pixels arranged in 20 × 20 matrix to form a scintillator block, which was optically coupled to a 1-inch-square position-sensitive photomultiplier tube (PSPMT). The GAGG detector was encased in a 20-mm thick container and a pinhole collimator was mounted on its front. The gamma camera was set 1.2 m from the 35 cm × 35 cm × 5 cm plastic phantom in the proton therapy treatment room, and proton beams were irradiated to the phantom with two proton energies.
RESULTS
The gamma camera had spatial resolution of ~6.7 cm and sensitivity of 3.2 × 10(-7) at 1 m from the collimator surface. For both proton energies, positron distribution in the phantom could be imaged by the gamma camera with 10-min acquisition. The lengths of the range of protons measured from the images were almost identical to the simulation results.
CONCLUSIONS
These results indicate that the developed high-energy gamma camera is useful for imaging positron distributions in proton therapy.
Topics: Electrons; Equipment Design; Gamma Cameras; Humans; Phantoms, Imaging; Proton Therapy; Sodium Radioisotopes
PubMed: 25476773
DOI: 10.1007/s12149-014-0936-4 -
Journal of Nuclear Medicine Technology Mar 2014Combined PET and SPECT scanning can give supplementary information. However, activity from PET radionuclides can cause background counts and increased dead time in γ...
UNLABELLED
Combined PET and SPECT scanning can give supplementary information. However, activity from PET radionuclides can cause background counts and increased dead time in γ camera imaging (SPECT or planar) because the 511-keV photons can penetrate collimators designed for lower energies. This study investigated how to manage this issue, including what levels of PET radionuclides can be tolerated when a γ-camera investigation is performed.
METHODS
Different combinations of (68)Ga (PET radionuclide), (99m)Tc (low-energy radionuclide), and (111)In (medium-energy radionuclide) were scanned by a γ camera. Standard low-, medium-, and high-energy collimators were used with the γ camera. Dead time and counts near and distant from the sources were recorded.
RESULTS
Down scatter from 511 keV can give rise to a considerable number of counts within the (99m)Tc or (111)In energy windows, especially when the PET source is close to the camera head. Over the full camera head, the PET source can result in more counts per megabecquerel than the SPECT source ((99m)Tc or (111)In). Counts from the PET source were distributed over a large region of the camera head. With medium- and high-energy collimators, the sensitivity to the PET radionuclide was found to be about 10% of the sensitivity to (99m)Tc and about 20% of the sensitivity to (111)In, as measured within a 3-cm-radius region of interest.
CONCLUSION
If PET radionuclides of activity 1 MBq or higher are present in the patient at the time of SPECT, a medium-energy collimator should be used. Counts from PET sources will in SPECT usually be seen as a diffuse background rather than as foci. The thick septa of high-energy collimators may result in structure in the image, and a high-energy collimator is recommended only if PET activity is greater than 10 MBq.
Topics: Half-Life; Positron-Emission Tomography; Reference Standards; Tomography, Emission-Computed, Single-Photon
PubMed: 24470597
DOI: 10.2967/jnmt.113.131003 -
Kaku Igaku. the Japanese Journal of... Apr 1998To measure myocardial blood flow, Nitrogen-13 ammonia. Oxygen-15 water, Rubidium-82 and et al. are used. Each has merit and demerit. By measuring myocardial coronary... (Review)
Review
To measure myocardial blood flow, Nitrogen-13 ammonia. Oxygen-15 water, Rubidium-82 and et al. are used. Each has merit and demerit. By measuring myocardial coronary flow reserve, the decrease of flow reserve during dipyridamole in patients with hypercholesterolemia or diabetes mellitus without significant coronary stenosis was observed. The possibility of early detection of atherosclerosis was showed. As to myocardial metabolism, glucose metabolism is measured by Fluorine-18 fluorodexyglucose (FDG), and it is considered as useful for the evaluation of myocardial viability. We are using FDG to evaluate insulin resistance during insulin clamp in patients with diabetes mellitus by measuring glucose utilization rate of myocardium and skeletal muscle. FFA metabolism has been measured by 11C-palmitate, but absolute quantification has not been performed. Recently the method for absolute quantification was reported, and new radiopharmaceutical 18F-FTHA was reported. Oxygen metabolism has been estimated by 11C-acetate. Myocardial viability, cardiac efficiency was evaluated by oxygen metabolism. As to receptor or sympathetic nerve end, cardiac insufficiency or cardiac transplantation was evaluated. Imaging of positron emitting radiopharmaceutical by gamma camera has been performed. Collimator method is clinically useful for cardiac imaging of viability study.
Topics: Coronary Circulation; Diabetes Mellitus, Type 2; Fluorodeoxyglucose F18; Gamma Cameras; Glucose; Heart; Humans; Myocardium; Oxygen Consumption; Tomography, Emission-Computed; Tomography, Emission-Computed, Single-Photon
PubMed: 9642928
DOI: No ID Found -
Seminars in Interventional Radiology Oct 2021Transarterial radioembolization with yttrium-90 ( Y) is a mainstay for the treatment of liver cancer. Imaging the distribution following delivery is a concept that... (Review)
Review
Transarterial radioembolization with yttrium-90 ( Y) is a mainstay for the treatment of liver cancer. Imaging the distribution following delivery is a concept that dates back to the 1960s. As β particles are created during Y decay, bremsstrahlung radiation is created as the particles interact with tissues, allowing for imaging with a gamma camera. Inherent qualities of bremsstrahlung radiation make its imaging difficult. SPECT and SPECT/CT can be used but suffer from limitations related to low signal-to-noise bremsstrahlung radiation. However, with optimized imaging protocols, clinically adequate images can still be obtained. A finite but detectable number of positrons are also emitted during Y decay, and many studies have demonstrated the ability of commercial PET/CT and PET/MR scanners to image these positrons to understand Y distribution and help quantify dose. PET imaging has been proven to be superior to SPECT for quantitative imaging, and therefore will play an important role going forward as we try and better understand dose/response and dose/toxicity relationships to optimize personalized dosimetry. The availability of PET imaging will likely remain the biggest barrier to its use in routine post- Y imaging; thus, SPECT/CT imaging with optimized protocols should be sufficient for most posttherapy subjective imaging.
PubMed: 34629714
DOI: 10.1055/s-0041-1735569 -
Cancer Biotherapy & Radiopharmaceuticals Feb 2001
Topics: Electrons; Fluorine Radioisotopes; Fluorodeoxyglucose F18; Gamma Cameras; Humans; Multicenter Studies as Topic; Neoplasms; Occupational Health; Prospective Studies; Radiometry; Radiopharmaceuticals; Safety; Technology, Radiologic; Tomography, Emission-Computed; United States
PubMed: 11279793
DOI: 10.1089/108497801750095943 -
Radiological Physics and Technology Sep 2022Compton imaging exploits inelastic scattering, known as Compton scattering, using a Compton camera consisting of a scatterer detector in the front layer and an absorber... (Review)
Review
Compton imaging exploits inelastic scattering, known as Compton scattering, using a Compton camera consisting of a scatterer detector in the front layer and an absorber detector in the back layer. This method was developed for astronomy, and in recent years, research and development for environmental and medical applications has been actively conducted. Compton imaging can discriminate gamma rays over a wide energy range from several hundred keV to several MeV. Therefore, it is expected to be applied to the simultaneous imaging of multiple nuclides in nuclear medicine and prompt gamma ray imaging for range verification in particle therapy. In addition, multiple gamma coincidence imaging is expected to be realized, which allows the source position to be determined from a single coincidence event using nuclides that emit multiple gamma rays simultaneously, such as nuclides that emit a single gamma ray simultaneously with positron decay. This review introduces various efforts toward the practical application of Compton imaging in the medical field, including in vivo studies, and discusses its prospects.
Topics: Diagnostic Imaging; Electrons; Gamma Rays; Monte Carlo Method; Radionuclide Imaging
PubMed: 35867197
DOI: 10.1007/s12194-022-00666-2 -
Physics in Medicine and Biology May 2021Nuclear medical imaging devices, such as those enabling photon emission imaging (gamma camera, single photon emission computed tomography, or positron emission imaging),... (Review)
Review
Nuclear medical imaging devices, such as those enabling photon emission imaging (gamma camera, single photon emission computed tomography, or positron emission imaging), that are typically used in today's clinics are optimized for assessing large portions of the human body, and are classified as whole-body imaging systems. These systems have known limitations for organ imaging, therefore application-specific devices have been designed, constructed and evaluated. These devices, given their compact nature and superior technical characteristics, such as their higher detection sensitivity and spatial resolution for organ imaging compared to whole-body imaging systems, have shown promise for niche applications. Several of these devices have further been integrated with complementary anatomical imaging devices. The objectives of this review article are to (1) provide an overview of such application-specific nuclear imaging devices that were developed over the past two decades (in the twenty-first century), with emphasis on brain, cardiac, breast, and prostate imaging; and (2) discuss the rationale, advantages and challenges associated with the translation of these devices for routine clinical imaging. Finally, a perspective on the future prospects for application-specific devices is provided, which is that sustained effort is required both to overcome design limitations which impact their utility (where these exist) and to collect the data required to define their clinical value.
Topics: Gamma Cameras; Humans; Male; Tomography, Emission-Computed, Single-Photon; Whole Body Imaging
PubMed: 33770765
DOI: 10.1088/1361-6560/abf275 -
Journal of Nuclear Medicine : Official... Dec 1985Based on a double-headed rotating uncollimated scintillation camera system, a positron imaging device was developed. After a rotating data acquisition in coincidence...
Based on a double-headed rotating uncollimated scintillation camera system, a positron imaging device was developed. After a rotating data acquisition in coincidence mode, 16 transverse section images are reconstructed by back projection. To obtain a uniform response, a limited angle reconstruction option is incorporated in this process. After correction for the system response by a three-dimensional deconvolution technique, the 16 transverse section images are stored on disk as a standard patient study for further analysis. The system can also be operated in a stationary mode. In this mode longitudinal tomographic images are obtained. Return to single photon scintigraphy is possible by remounting the collimators and by switching off the coincidence electronics.
Topics: Brain; Humans; Models, Structural; Technology, Radiologic; Thyroid Gland; Tomography, Emission-Computed
PubMed: 3877798
DOI: No ID Found -
Nuclear Medicine and Molecular Imaging Jun 2019Targeted alpha therapy (TAT) is an active area of drug development as a highly specific and highly potent therapeutic modality that can be applied to many types of... (Review)
Review
Targeted alpha therapy (TAT) is an active area of drug development as a highly specific and highly potent therapeutic modality that can be applied to many types of late-stage cancers. In order to properly evaluate its safety and efficacy, understanding biokinetics of alpha-emitting radiopharmaceuticals is essential. Quantitative imaging of alpha-emitting radiopharmaceuticals is often possible via imaging of gammas and positrons produced during complex decay chains of these radionuclides. Analysis of the complex decay chains for alpha-emitting radionuclides (Tb-149, At-211, Bi-212 (decayed from Pb-212), Bi-213, Ra-223, Ac-225, and Th-227) with relevance to imageable signals is attempted in this mini-review article. Gamma camera imaging, single-photon emission computed tomography, positron emission tomography, bremsstrahlung radiation imaging, Cerenkov luminescence imaging, and Compton cameras are briefly discussed as modalities for imaging alpha-emitting radiopharmaceuticals.
PubMed: 31231438
DOI: 10.1007/s13139-019-00589-8