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Annals of the Academy of Medicine,... Mar 2004Molecular imaging with positron-emitting radionuclides is playing an increasingly important role in the diagnosis and staging of malignant disease and in monitoring... (Review)
Review
Molecular imaging with positron-emitting radionuclides is playing an increasingly important role in the diagnosis and staging of malignant disease and in monitoring response to therapy. To meet this challenge, significant improvements in the performance of the imaging technology have been achieved in recent years. Such developments are subject to the constraints imposed by the physics of positron emission tomography (PET) and the main objectives in designing or improving PET scanners are to achieve high spatial resolution and sensitivity while maximising the true coincidence count rate relative to contributions from noise processes. Noise contributions in PET include not only statistical effects associated with photon counting but also background processes such as scatter and random coincidences. The recent developments of new, faster scintillators and electronics for PET detectors, as well as statistically-based algorithms that reconstruct fully three-dimensional (3D) PET images in minutes, have dramatically reduced clinical imaging times while improving image quality. A recent advance, the combination of functional imaging and computed tomography (CT) in the PET/CT scanner has further reduced the study duration by eliminating the lengthy PET transmission scan and providing accurate anatomical localisation of functional abnormalities. PET imaging technology has now improved to where a combined anatomical and functional clinical study can be completed in less than 10 minutes--although taking advantage of such high throughput potential will challenge patient management in diagnostic imaging departments. This paper reviews the physical principles underlying PET and summarises the recent developments in PET scanner technology, from the introduction of new PET detectors to the development of the combined PET/CT scanner.
Topics: Algorithms; Equipment Design; Gamma Cameras; Humans; Imaging, Three-Dimensional; Technology, Radiologic; Tomography, Emission-Computed; Tomography, X-Ray Computed
PubMed: 15098626
DOI: No ID Found -
Journal of Nuclear Medicine : Official... Apr 2014Radionuclide renal scintigraphy provides important functional data to assist in the diagnosis and management of patients with a variety of suspected genitourinary tract... (Review)
Review
Radionuclide renal scintigraphy provides important functional data to assist in the diagnosis and management of patients with a variety of suspected genitourinary tract problems, but the procedures are underutilized. Maximizing the utility of the available studies (as well as the perception of utility by referring physicians) requires a clear understanding of the clinical question, attention to quality control, acquisition of the essential elements necessary to produce an informed interpretation, and production of a report that presents a coherent impression that specifically addresses the clinical question and is supported by data contained in the report. To help achieve these goals, part 1 of this review covers information that should be provided to the patient before the scan, describes the advantages and limitations of the available radiopharmaceuticals, discusses quality control elements needed to optimize the study, summarizes approaches to the measurements of renal function, and focuses on recommended quantitative indices and their diagnostic applications. Although the primary focus is the adult patient, aspects of the review also apply to the pediatric population.
Topics: Animals; Extravasation of Diagnostic and Therapeutic Materials; Gamma Cameras; Humans; Isotope Labeling; Kidney; Kidney Function Tests; Patient Positioning; Positron-Emission Tomography; Quality Control; Radioisotopes; Radiopharmaceuticals; Urodynamics; Urology
PubMed: 24549283
DOI: 10.2967/jnumed.113.133447 -
Journal of Applied Clinical Medical... Jul 2021Electron radiation therapy dose distributions are affected by irregular body surface contours. This study investigates the feasibility of three-dimensional (3D) cameras...
PURPOSE
Electron radiation therapy dose distributions are affected by irregular body surface contours. This study investigates the feasibility of three-dimensional (3D) cameras to substitute for the treatment planning computerized tomography (CT) scan by capturing the body surfaces to be treated for accurate electron beam dosimetry.
METHODS
Dosimetry was compared for six electron beam treatments to the nose, toe, eye, and scalp using full CT scan, CT scan with Hounsfield Unit (HU) overridden to water (mimic 3D camera cases), and flat-phantom techniques. Radiation dose was prescribed to a depth on the central axis per physician's order, and the monitor units (MUs) were calculated. The 3D camera spatial accuracy was evaluated by comparing the 3D surface of a head phantom captured by a 3D camera and that generated with the CT scan in the treatment planning system. A clinical case is presented, and MUs were calculated using the 3D camera body contour with HU overridden to water.
RESULTS
Across six cases the average change in MUs between the full CT and the 3Dwater (CT scan with HU overridden to water) calculations was 1.3% with a standard deviation of 1.0%. The corresponding hotspots had a mean difference of 0.4% and a standard deviation of 1.9%. The 3D camera captured surface of a head phantom was found to have a 0.59 mm standard deviation from the surface derived from the CT scan. In-vivo dose measurements (213 ± 8 cGy) agreed with the 3D-camera planned dose of 209 ± 6 cGy, compared to 192 ± 6 cGy for the flat-phantom calculation (same MUs).
CONCLUSIONS
Electron beam dosimetry is affected by irregular body surfaces. 3D cameras can capture irregular body contours which allow accurate dosimetry of electron beam treatment as an alternative to costly CT scans with no extra exposure to radiation. Tools and workflow for clinical implementation are provided.
Topics: Electrons; Humans; Phantoms, Imaging; Radiometry; Radiotherapy Dosage; Radiotherapy Planning, Computer-Assisted; Tomography, X-Ray Computed
PubMed: 34042253
DOI: 10.1002/acm2.13283 -
ACS Central Science Sep 2019Here we apply microcrystal electron diffraction (MicroED) to the structural determination of transition-metal complexes. We find that the simultaneous use of 300 keV...
Here we apply microcrystal electron diffraction (MicroED) to the structural determination of transition-metal complexes. We find that the simultaneous use of 300 keV electrons, very low electron doses, and an ultrasensitive camera allows for the collection of data without cryogenic cooling of the stage. This technique reveals the first crystal structures of the classic zirconocene hydride, colloquially known as "Schwartz's reagent", a novel Pd(II) complex not amenable to solution-state NMR or X-ray crystallography, and five other paramagnetic and diamagnetic transition-metal complexes.
PubMed: 31572777
DOI: 10.1021/acscentsci.9b00403 -
Cancer Imaging : the Official... Apr 2024PSMA PET/CT is the most sensitive molecular imaging modality for prostate cancer (PCa), yet much of the developing world has little or no access to PET/CT. [Tc]Tc-PSMA...
BACKGROUND
PSMA PET/CT is the most sensitive molecular imaging modality for prostate cancer (PCa), yet much of the developing world has little or no access to PET/CT. [Tc]Tc-PSMA scintigraphy (PS) is a cheaper and more accessible gamma camera-based alternative. However, many resource-constrained departments have only a single camera without tomographic or hybrid imaging functionality, and camera time is frequently in high demand. Simplifying imaging protocols by limiting the field of view (FOV) and omitting SPECT/CT or even SPECT may provide a partial solution. The aim was thus to determine the adequacy of PS planar-only and/or SPECT-only imaging protocols with a limited FOV.
METHODS
The scans of 95 patients with histologically proven PCa who underwent PS with full-body planar and multi-FOV SPECT/CT were reviewed. The detection rates for uptake in the prostate gland/bed and in metastases were compared on planar, SPECT, and SPECT/CT. The agreement between modalities was calculated for the detection of metastases and for staging. The impact of imaging a limited FOV was determined.
RESULTS
Pathological prostatic uptake was seen in all cases on SPECT/CT (excluding two post-prostatectomy patients), 90.3% of cases on SPECT, and 15.1% on planar images (p < 0.001). Eleven (11.7%) patients had seminal vesicle involvement on SPECT/CT, which was undetectable/indistinguishable on planar images and SPECT. The agreement between modalities was moderate to good (κ = 0.41 to 0.61) for the detection of nodal metastases, with detection rates that did not differ significantly (SPECT/CT = 11.6%, SPECT = 8.4%, planar = 5.3%). Detection rates for bone metastases were 14.7% (SPECT/CT) and 11.6% (SPECT and planar). Agreement between modalities for the detection of bone metastases was good (κ = 0.73 to 0.77). Three (3.1%) patients had visceral metastases on SPECT/CT, two of which were detected on SPECT and planar. There was good agreement between modalities for the TNM staging of patients (κ = 0.70 to 0.88). No metastatic lesions were missed on the limited FOV images.
CONCLUSION
When PS scintigraphy is performed, SPECT/CT is recommended. However, the lack of SPECT/CT capabilities should not preclude the use of PS in the presence of limited resources, as both planar and SPECT imaging are adequate and will correctly stage most PCa patients. Furthermore, time-based optimisations are achievable by limiting the FOV to exclude the distal lower limbs.
Topics: Male; Humans; Positron Emission Tomography Computed Tomography; Retrospective Studies; Resource-Limited Settings; Tomography, Emission-Computed, Single-Photon; Single Photon Emission Computed Tomography Computed Tomography; Prostatic Neoplasms; Bone Neoplasms
PubMed: 38556864
DOI: 10.1186/s40644-024-00693-9 -
Acta Cardiologica Sinica Mar 2016Radionuclide myocardial perfusion imaging (MPI) with single photon emission computed tomography (SPECT) has been widely used clinically as one of the major functional... (Review)
Review
UNLABELLED
Radionuclide myocardial perfusion imaging (MPI) with single photon emission computed tomography (SPECT) has been widely used clinically as one of the major functional imaging modalities for patients with coronary artery disease (CAD) for decades. Ample evidence has supported the use of MPI as a useful and important tool in the diagnosis, risk stratification and treatment planning for CAD. Although popular in the United States, MPI has become the most frequently used imaging modality among all nuclear medicine tests in Taiwan. However, it should be acknowledged that MPI SPECT does have its limitations. These include false-positive results due to certain artifacts, false-negative due to balanced ischemia, complexity and adverse reaction arising from current pharmacological stressors, time consuming nature of the imaging procedure, no blood flow quantitation and relatively high radiation exposure. The purpose of this article was to review the recent trends in nuclear cardiology, including the utilization of positron emission tomography (PET) for MPI, new stressor, new SPECT camera with higher resolution and higher sensitivity, dynamic SPECT protocol for blood flow quantitation, new software of phase analysis for evaluation of LV dyssynchrony, and measures utilized for reducing radiation exposure of MPI.
KEY WORDS
Coronary artery disease • Myocardial flow reserve • Myocardial perfusion imaging • Phase analysis • PET • SPECT.
PubMed: 27122946
DOI: 10.6515/acs20150803a -
The British Journal of Radiology Jul 2022The Ionising Radiation (Medical Exposure) Regulations require employers to appoint suitable medical physics experts (MPE) for nuclear medicine services, and they also...
The Ionising Radiation (Medical Exposure) Regulations require employers to appoint suitable medical physics experts (MPE) for nuclear medicine services, and they also define the areas where MPEs are required to provide advice and specify matters that they must contribute towards. Applications for employer licences under IR(ME)R require employers to specify the level of MPE support available and if this is provided by onsite MPEs or remotely. Assessment of these applications by the Administration of Radioactive Substances Advisory Committee (ARSAC) has highlighted variability in the levels of MPE support being provided for similar services across the UK. A working party including representatives from IPEM, ARSAC, BIR and BNMS was formed and has produced these recommendations on MPE support. Nuclear medicine services were divided into seven broad categories and MPE support for each category has been considered. However, some services that differ from the scenarios provided in this guidance may require different levels of MPE support. Positron emission tomography (PET)/CT and gamma camera imaging have been considered separately here, although it is recognised that both PET/CT and gamma cameras are often sited within the same department in many centres. The separation has been done for pragmatic purposes, as there are felt to be sufficient differences in the MPE role requirements. This guidance sets out recommendations for MPE support, and broader physics support, to run a safe nuclear medicine service and defines the responsibilities of these staff for a range of clinical nuclear medicine services. The recommendations on MPE support made are advice, but will assist employers in meeting regulatory requirements.
Topics: Humans; Muscle Spasticity; Nuclear Medicine; Physics; Positron Emission Tomography Computed Tomography; Spinocerebellar Ataxias; Tomography, X-Ray Computed
PubMed: 35604659
DOI: 10.1259/bjr.20211393 -
Journal of Nuclear Medicine : Official... Jan 2017Cerenkov luminescence imaging can image radiopharmaceuticals using a high-sensitivity charge-coupled device camera. However, Cerenkov luminescence emitted from the...
UNLABELLED
Cerenkov luminescence imaging can image radiopharmaceuticals using a high-sensitivity charge-coupled device camera. However, Cerenkov luminescence emitted from the radiopharmaceuticals is weak and has low penetration depth in biologic tissues, which severely limits the sensitivity and accuracy of Cerenkov luminescence imaging. This study presents 3-dimensional (3D) radiopharmaceutical-excited fluorescence tomography (REFT) using europium oxide (EO) nanoparticles, which enhances the Cerenkov luminescence signal intensity, improves the penetration depth, and obtains more accurate 3D distribution of radiopharmaceuticals.
METHODS
The enhanced optical signals of various radiopharmaceuticals (including NaI, F-FDG, GaCl, NaTcO) by EO nanoparticles were detected in vitro. The location and 3D distribution of the radiopharmaceuticals of REFT were then reconstructed and compared with those of Cerenkov luminescence tomography through the experiments with the phantom, artificial source-implanted mouse models, and mice bearing hepatocellular carcinomas.
RESULTS
The mixture of GaCl and EO nanoparticles possessed the strongest optical signals compared with the other mixtures. The in vitro phantom and implanted mouse studies showed that REFT revealed more accurate 3D distribution of GaCl REFT can detect more tumors than small-animal PET in hepatocellular carcinoma-bearing mice and achieved more accurate 3D distribution information than Cerenkov luminescence tomography.
CONCLUSION
REFT with EO nanoparticles significantly improves accuracy of localization of radiopharmaceuticals and can precisely localize the tumor in vivo.
Topics: Animals; Carcinoma, Hepatocellular; Cell Line, Tumor; Image Enhancement; Imaging, Three-Dimensional; Male; Metal Nanoparticles; Mice; Mice, Inbred BALB C; Mice, Nude; Microscopy, Fluorescence; Molecular Imaging; Phantoms, Imaging; Positron-Emission Tomography; Radiopharmaceuticals; Reproducibility of Results; Sensitivity and Specificity; Tomography, Optical; Whole Body Imaging
PubMed: 27660137
DOI: 10.2967/jnumed.116.180596 -
Heliyon Oct 2020Accurate, robust and reproducible delineation of tumour in Positron Emission Tomography (PET) is essential for diagnosis, treatment planning and response assessment.... (Review)
Review
Accurate, robust and reproducible delineation of tumour in Positron Emission Tomography (PET) is essential for diagnosis, treatment planning and response assessment. Since standardized uptake value (SUV) - a normalized semiquantitative parameter used in PET is represented by the intensity of the PET images and related to the radiotracer uptake, a SUV based threshold method is a natural choice to delineate the tumour. However, determination of an optimum threshold value is a challenging task due to low spatial resolution, and signal-to-noise ratio (SNR) along with finite image sampling constraint. The aim of the review is to summarize different fixed and adaptive threshold-based PET image segmentation approaches under a common mathematical framework Advantages and disadvantages of different threshold based methods are also highlighted from the perspectives of diagnosis, treatment planning and response assessment. Several fixed threshold values (30%-70% of the maximum SUV of the tumour (SUV)) have been investigated. It has been reported that the fixed threshold-based method is very much dependent on the SNR, tumour to background ratio (TBR) and the size of the tumour. Adaptive threshold-based method, an alternative to fixed threshold, can minimize these dependencies by accounting for tumour to background ratio (TBR) and tumour size. However, the parameters for the adaptive methods need to be calibrated for each PET camera system (e.g., scanner geometry, image acquisition protocol, reconstruction algorithm etc.) and it is not straight forward to implement the same procedure to other PET systems to obtain similar results. It has been reported that the performance of the adaptive methods is also not optimum for smaller volumes with lower TBR and SNR. Statistical analysis carried out on the NEMA thorax phantom images also indicates that regions segmented by the fixed threshold method are significantly different for all cases. On the other hand, the adaptive method provides significantly different segmented regions only for low TBR with different SNR. From this viewpoint, a robust threshold based segmentation method that will be less sensitive to , SNR, TBR and volume needs to be developed. It was really challenging to compare the performance of different threshold-based methods because the performance of each method was tested on dissimilar data set with different data acquisition and reconstruction protocols along with different TBR, SNR and volumes. To avoid such difficulties, it will be desirable to have a common database of clinical PET images acquired with different image acquisition protocols and different PET cameras to compare the performance of automatic segmentation methods. It is also suggested to report the changes in SNR and TBR while reporting the response using threshold based methods.
PubMed: 33163642
DOI: 10.1016/j.heliyon.2020.e05267 -
Journal of Applied Clinical Medical... Jun 2020The novel scintillator-based system described in this study is capable of accurately and remotely measuring surface dose during Total Skin Electron Therapy (TSET); this...
PURPOSE
The novel scintillator-based system described in this study is capable of accurately and remotely measuring surface dose during Total Skin Electron Therapy (TSET); this dosimeter does not require post-exposure processing or annealing and has been shown to be re-usable, resistant to radiation damage, have minimal impact on surface dose, and reduce chances of operator error compared to existing technologies e.g. optically stimulated luminescence detector (OSLD). The purpose of this study was to quantitatively analyze the workflow required to measure surface dose using this new scintillator dosimeter and compare it to that of standard OSLDs.
METHODS
Disc-shaped scintillators were attached to a flat-faced phantom and a patient undergoing TSET. Light emission from these plastic discs was captured using a time-gated, intensified, camera during irradiation and converted to dose using an external calibration factor. Time required to complete each step (daily QA, dosimeter preparation, attachment, removal, registration, and readout) of the scintillator and OSLD surface dosimetry workflows was tracked.
RESULTS
In phantoms, scintillators and OSLDs surface doses agreed within 3% for all data points. During patient imaging it was found that surface dose measured by OSLD and scintillator agreed within 5% and 3% for 35/35 and 32/35 dosimetry sites, respectively. The end-to-end time required to measure surface dose during phantom experiments for a single dosimeter was 78 and 202 sec for scintillator and OSL dosimeters, respectively. During patient treatment, surface dose was assessed at 7 different body locations by scintillator and OSL dosimeters in 386 and 754 sec, respectively.
CONCLUSION
Scintillators have been shown to report dose nearly twice as fast as OSLDs with substantially less manual work and reduced chances of human error. Scintillator dose measurements are automatically saved to an electronic patient file and images contain a permanent record of the dose delivered during treatment.
Topics: Electrons; Humans; Phantoms, Imaging; Radiation Dosimeters; Radiometry; Workflow
PubMed: 32306551
DOI: 10.1002/acm2.12880