Field Of View Gamma Camera Research Articles

Seracam: characterisation of a new small field of view hybrid gamma camera for nuclear medicine

BackgroundPortable gamma cameras are being developed for nuclear medicine procedures such as thyroid scintigraphy. This article introduces Seracam® – a new technology that combines small field of view gamma imaging with optical imaging – and reports its performance and suitability for small organ imaging.MethodsThe count rate capability, uniformity, spatial resolution, and sensitivity for 99mTc are reported for four integrated pinhole collimators of nominal sizes of 1 mm, 2 mm, 3 mm and 5 mm. Characterisation methodology is based on NEMA guidelines, with some adjustments necessitated by camera design. Two diagnostic scenarios – thyroid scintigraphy and gastric emptying – are simulated using clinically relevant activities and geometries to investigate application-specific performance. A qualitative assessment of the potential benefits and disadvantages of Seracam is also provided.ResultsSeracam’s performance across the measured characteristics is appropriate for small field of view applications in nuclear medicine. At an imaging distance of 50 mm, corresponding to a field of view of 77.6 mm × 77.6 mm, spatial resolution ranged from 4.6 mm to 26 mm and sensitivity from 3.6 cps/MBq to 52.2 cps/MBq, depending on the collimator chosen. Results from the clinical simulations were particularly promising despite the challenging scenarios investigated. The optimal collimator choice was strongly application dependent, with gastric emptying relying on the higher sensitivity of the 5 mm pinhole whereas thyroid imaging benefitted from the enhanced spatial resolution of the 1 mm pinhole. Signal to noise ratio in images was improved by pixel binning. Seracam has lower measured sensitivity when compared to a traditional large field of view gamma camera, for the simulated applications this is balanced by advantages such as high spatial resolution, portability, ease of use and real time gamma-optical image fusion and display.ConclusionThe results show that Seracam has appropriate performance for small organ 99mTc imaging. The results also show that the performance of small field of view systems must be considered holistically and in clinically appropriate scenarios.

CHARACTERIZATION OF A SMALL FOV PORTABLE GC: MediPROBE.

In this work, we evaluated the performance of the prototype SFOV MediPROBE developed at the University of Naples Federico II through the protocol proposed by (Bhatia B.S., Bugby S.L., Lees J.E., Perkins A.C. A scheme for assessing the performance characteristics of a small field of-view gamma cameras. Physica. Medica., 31 (1), pp. 98-103. (2015) doi: 10.1016/j.ejmp.2014.08.004). We extensively investigated a new device configuration where the pinhole collimator was placed outside the housing of the probe, in order to increase the system spatial resolution, and the pixel size was doubled, in order to reduce the charge sharing effect. The experimental measurements show that the spatial resolution is enhanced by only about 10%, but the sensitivity decreases strongly. Therefore, the trade-off between these two features does not seem to be advantageous. In addition, our experiments suggest that the charge sharing effect is not completely canceled. Despite these results, the features of this device appear suitable for intraoperative surgical survey. We aim to use this device in the clinical practice for the intraoperative imaging of lymph nodes, breast, thyroid and parathyroid tumors.

Hepato and Cardiotoxicity of Chemotherapeutic Treatment Evaluated by Means of Small Animal Imaging.

Chemotherapy is one of the most common approaches for cancer treatment. Particularly Doxorubicin has been proven to be effective in the treatment of many soft and solid tumors for locally advanced and metastatic cancer. It is not easy to clinically evaluate the chemotoxic or chemoprotective effect of some drugs, even more when there is a subclinical toxicity. To determine the usefulness of the hepatobiliary, colloid and cardiac scintigraphies, employing99mTcdisida, 99mTc-phytate and 99mTc-sestamibi respectively, in the evaluation of the hepato and cardiotoxicity of two chemotherapeutic treatments assessed in rats. Two groups were submitted to doxorubicin (DOX) treatment and one was co-administered with histamine (DOX+HIS). Static 99mTc-phytate and 99mTc-sestamibi scintigraphies as well as a dynamic 99mTc-disida study were performed in a small field of view gamma camera at: 0 weeks (control), 1 week and 2 weeks of treatment. Imagenological parameters were calculated: Liver/Bone Marrow ratio (L/BM), Heart/Background ratio (H/B) and time to the maximum (Tmax) for 99mTc-phytate, 99mTc-sestamibi and 99mTc-disida extraction, respectively. Control (L/BM= 98±3; H/B=2.3±0.4; Tmax=8±3), DOX (L/BM: 85±3, 80±3; H/B, 3.5±0.5, 3.3±0.5 and Tmax 6±1, 4±1) for 1 and 2 weeks respectively and DOX+HIS (L/BM: 99±0.3, 98±1; H/B 2.9±0.5, 2.9±0.5 and Tmax, 8±2, 9±2) for 1 and 2 weeks, respectively. Histological analysis showed cardio and hepatotoxicity induced by doxorubicin. Imagenological parameters showed differences among treated and control groups and between both chemotherapy treatments. Thus, these radiopharmaceutical functional approaches were able to reflect heart and liver toxicity produced by doxorubicin.

Integrated ultrasound and gamma imaging probe for medical diagnosis

In the last few years, integrated multi-modality systems have been developed, aimed at improving the accuracy of medical diagnosis correlating information from different imaging techniques. In this contest, a novel dual modality probe is proposed, based on an ultrasound detector integrated with a small field of view single photon emission gamma camera. The probe, dedicated to visualize small organs or tissues located at short depths, performs dual modality images and permits to correlate morphological and functional information. The small field of view gamma camera consists of a continuous NaI:Tl scintillation crystal coupled with two multi-anode photomultiplier tubes. Both detectors were characterized in terms of position linearity and spatial resolution performances in order to guarantee the spatial correspondence between the ultrasound and the gamma images. Finally, dual-modality images of custom phantoms are obtained highlighting the good co-registration between ultrasound and gamma images, in terms of geometry and image processing, as a consequence of calibration procedures.

Assessment of the performance of small field of view gamma cameras for sentinel node imaging.

To develop a method for the assessment of small field of view (SFOV) gamma cameras using a novel phantom designed to simulate the localization of sentinel nodes in the presence of a high-activity injection site. The phantom consisted of a cube-shaped acrylic glass support frame. Sixteen acrylic glass plates and nine bars were stacked within the frame to allow a variable configuration of the simulated node depth and node-to-injection site separation. Syringes filled with Tc were used to simulate activity at the injection site and node. Scintigraphic imaging was carried out and the images were assessed subjectively and quantitatively through calculation of the contrast-to-noise ratio. The detection performance of an SFOV gamma camera was then compared with that of a large field of view gamma camera. The detectability studies showed that the SFOV gamma camera could detect low activity in nodes by visual examination of images and with contrast-to-noise ratios ranging from 3 to 62. In particular, the phantom showed the limits of node detection using an SFOV gamma camera over activity ratios less than 1 : 100 and at depths below 45 mm with 25 mm of node-to-injection site separation. Visual subjective assessment of images acquired under the same conditions showed that the SFOV gamma camera was superior to a large field of view camera for the detection of nodes at a node-to-injection site separation of 25 mm. A low-cost phantom has been designed and fabricated that provides a versatile method for the assessment of SFOV gamma cameras intended for sentinel node imaging.

Intraoperative Use of a Portable Large Field of View Gamma Camera and Handheld Gamma Detection Probe for Radioguided Localization and Prediction of Complete Surgical Resection of Gastrinoma: Proof of Concept

Surgical management of Zollinger-Ellison syndrome (ZES) relies on localization and resection of all tumor foci. We describe the benefit of combined intraoperative use of a portable large field of view gamma camera (LFOVGC) and a handheld gamma detection probe (HGDP) for indium-111 ((111)In)-pentetreotide radioguided localization and confirmation of gastrinoma resection in ZES. Five patients (6 cases) with (111)In-pentetreotide-avid ZES were evaluated. Patients were injected with (111)In-pentetreotide for diagnostic imaging the day before surgery. Intraoperatively, an HGDP and LFOVGC were used to localize (111)In-pentetreotide-avid lesions, guide resection, assess specimens for (111)In-pentetreotide activity, and to verify lack of abnormal post-resection surgical field activity. Large field of view gamma camera imaging and HGDP-assisted detection were helpful for localization and guided resection of tumor and removal of (111)In-pentetreotide-avid tumor foci in all cases. In 3 of 5 patients (3 of 6 cases), these techniques led to detection and resection of additional tumor foci beyond those detected by standard surgical techniques. The (111)In-pentetreotide-positive or-negative specimens correlated with neuroendocrine tumors or benign pathology, respectively. In one patient with mild residual focal activity on post-resection portable LFOVGC imaging, thought to be artifact, had recurrence of disease in the same area 5 months after surgery. Real-time LFOVGC imaging and HGDP use for surgical management of gastrinoma improve success of localizing and resecting all neuroendocrine tumor-positive tumor foci, providing instantaneous navigational feedback. This approach holds potential for improving long-term patient outcomes in patients with ZES.

Characterization of a small CsI(Na)-WSF-SiPM gamma camera prototypeusing 99mTc

A small field of view gamma camera is being developed, aiming for applications in scintimammography, sentinel lymph node detection or small animal imaging and research. The proposed wavelength-shifting fibre (WSF) gamma camera consists of two perpendicular sets of WSFs covering both sides of a CsI(Na) crystal, such that the fibres positioned at the bottom of the crystal provide the x coordinate and the ones on top the y coordinate of the gamma photon interaction point. The 2D position is given by highly sensitive photodetectors reading out each WSF and the energy information is provided by PMTs that cover the full detector area. This concept has the advantage of using N+N instead of N × N photodetectors to cover an identical imaging area, and is being applied using for the first time SiPMs. Previous studies carried out with 57Co have proved the feasibility of this concept using SiPM readout. In this work, we present experimental results from true 2D image acquisitions with a 10+10 SiPMs prototype, i.e. 10 × 10 mm2, using a parallel-hole collimator and different samples filled with 99mTc solution. The performance of the small prototype in these conditions is evaluated through the characterization of different gamma camera parameters, such as energy and spatial resolution. Ongoing advances towards a larger prototype of 100+100 SiPMs (10 × 10 cm2) are also presented.

Development of correction schemes for a small field of view gamma camera

Purpose The goal of this study is to develop data correction schemes for a small field of view (SFOV) high resolution gamma camera detector for a small organ dedicated system such as breast, thyroid and joints.

Modelling image profiles produced with a small field of view gamma camera with a single pinhole collimator

Gamma cameras making use of parallel-hole collimators have a long history in medical imaging. Pinhole collimators were used in the original gamma camera instruments and have been used more recently in dedicated organ specific systems, intraoperative instruments and for small animal imaging, providing higher resolution over a smaller field of view than the traditional large field of view systems.With the resurgence of interest in the use of pinhole collimators for small field of view (SOV) medical gamma cameras, it is important to be able to accurately determine their response under various conditions. Several analytical approaches to pinhole response have been reported in the literature including models of 3D pinhole imaging systems. Success has also been reported in the use of Monte Carlo simulations; however this approach can require significant time and computing power.This report describes a 2D model that was used to investigate some common problems in pinhole imaging, the variation in resolution over the field of view and the use of `point' sources for quantifying pinhole response.

WE‐A‐213CD‐01: Molecular Imaging of the Breast

Molecular imaging of the breast using either SPECT or PET based radiopharmaceuticals is a relatively new area of focus for nuclear medicine and has grown in importance over the last few years with the development of specialized small field of view gamma cameras and small PET systems designed to provide high resolution functional images of the breast. Molecular Breast Imaging (MBI) / Breast Specific Gamma imaging (BSGI): MBI and BSGI are currently performed with Tc‐99m sestamibi and have shown a high sensitivity for the detection of small breast lesions, with reported sensitivities of ∼90%. Sensitivity is lowest for tumors < 5 mm in size. This talk will review the technology behind both MBI and BSGI and the primary clinical applications. It will also review the potential use of MBI as a screening technique. Recent studies have shown that it may be considerably more sensitive than mammography in women with dense breast tissue. A significant issue with MBI / BSGI is radiation burden and this talk will review efforts to increase the sensitivity of these technologies to allow a reduction in the administered dose of radiopharmaceutical, and thereby achieve a comparable radiation burden to mammography. Positron Emission Mammography (PEM): PEM is currently performed on a dual detector system incorporating 2 scanning arrays of BGO crystals providing limited angle tomographic imaging. Studies using F‐18 FDG have shown PEM to have comparable sensitivity to MRI for the detection of breast cancer. It is a useful tool in the preoperative assessment of disease extent and in evaluating response to neoadjuvant therapy. As with single photon systems, sensitivity is lowest for tumors < 5 mm in size. Current systems employ doses of 10 mCi F‐18 FDG. Recent technical developments have seen the emergence of systems using small ring detectors or rotating planar detectors that provide full tomographic views of the breast. Clinical studies are expected to show improvements in spatial resolution and a reduction in the administered dose of F‐18 required. COI: The author and Mayo Clinic receive royalties from patents licensed to Gamma Medica Ideas, a manufacturer of MBI systems. Learning Objective:1) Understand the different technologies (PEM,MBI, BSGI) and detector configurations now available for molecular imaging of the breast. 2) Understand the potential applications for molecular imaging of the breast in both the diagnostic and screening environments. 3) Compare the strengths and weakness of molecular imaging techniques with other breast imaging modalities. 4) Appreciate the potential future applications of this technology in the understanding of breast disease. 5) Demonstrate understanding of the radiation dose implications of current radiopharmaceuticals and how the dose can be reduced with new technologies and radiopharmaceuticals.

Small prototype gamma camera based on wavelength-shifting fibres

We are studying and developing a small field of view gamma camera based on wavelength-shifting optical fibres coupled to both sides of an inorganic scintillation crystal and using for the light readout highly sensitive photon detectors, namely silicon photomultipliers (SiPMs) and high efficiency multi-anode photomultiplier tubes (MaPMTs). The coupling of the fibres in orthogonal directions allows obtaining 2D position information, while the energy signal is provided by a PMT. A first prototype laboratory system has been developed using a custom-made 50 × 50 × 3 mm3 CsI(Na) crystal with embedded 1 mm diameter fibres and reading out the light from several fibres in each direction, both with individual SiPMs and with a MaPMT. Proof-of-concept studies and results obtained with these systems using 57Co are presented and compared. The application of optical fibres combined with highly sensitive SiPMs or MaPMTs as light sensors in a compact gamma camera has the potential to improve the spatial resolution to the 1-2 mm FWHM level, thus improving the sensitivity of typical scintigraphy techniques and making such camera clinically useful. Results demonstrate the feasibility and imaging capability of the system using both types of photon detectors for imaging. In the case of SiPMs, a temperature cooling system is necessary to improve the SNR and consequently achieve a better imaging performance. The development of larger prototypes with 10 × 10 cm2 and 12 × 12 cm2 is under way, using 1 mm2 SiPMs and 64 anode PMTs, respectively.

Design and use of mini-phantoms for high resolution planar gamma cameras

There is now wide spread interest in the application of small field of view gamma cameras for clinical use in operating theatres, intensive care units and bedside imaging. The development of these imaging systems some of which have improved spatial resolution has necessitated a reappraisal of the suitability of conventional phantoms intended for use with gamma cameras. The testing of imagers having increased system resolution requires phantoms and test objects of smaller dimensions. We have investigated the use of high resolution mini-phantoms for the evaluation of planar imaging devices with spatial resolution of the order of 1 mm. We present images of a number of phantoms that show their suitability for evaluating high resolution planar gamma cameras. It is also apparent that there are a number of practical difficulties that have not been previously reported when using liquid filled phantoms with hole sizes between 1 and 4 mm. In particular problems of filling small diameter holes and liquid surface tension effects can limit the utility of these phantoms. Initial observations when imaging mini-phantoms with a high resolution CCD based gamma camera are presented.

PTH-032 Scintigraphic gastric emptying: clinical impression vs outcome

<h3>Introduction</h3> In patients presenting with upper gastrointestinal (GI) symptoms, clinical impression of rapid or delayed gastric emptying (GE) may be misleading. This study was undertaken to determine the frequency of rapid/delayed GE compared to clinical presentation in patients referred for GE scintigraphy. <h3>Methods</h3> A retrospective review of 642 (234 males, 408 females, mean age 45 years old) consecutive GE studies was performed. Each patient received a standard solid meal containing two large eggs labelled with 12 MBq of 99mTc-tin colloid and a glass of water. Static imaging in upright position (anterior and posterior 60 s) every 15 min was performed for 150 min using a large field of view gamma camera fitted with a low energy collimator and a computer system. GE was classified as normal, rapid and delayed based on half-emptying time and percentage retained at 150 min. <h3>Results</h3> Seventy (11%) patients with suspected rapid and 572 (89%) with suspected delayed GE were studied. Normal, rapid and delayed GE, respectively, were observed in 11 (16%), 54 (77%) and 5 (7%) patients with the clinical suspicion of rapid GE and 178 (31%), 215 (37%) and 178 (31%) patients with suspected delay in GE. One patient with suspected delay had a biphasic GE pattern. Positive Predictive Value (PPV) of clinical suspicion for rapid GE was 77% while PPV of clinical suspicion for delayed GE was 31%. <h3>Conclusion</h3> Our experience demonstrates that clinical impression is often an unreliable predictor of the outcome of GE scintigraphy, especially in patients suspected of having a delayed GE. GE scintigraphy using solid egg meal is a very useful investigation in the management of patients presenting with complex upper GI symptoms.

TU-C-210A-03: Molecular Imaging of the Breast

Recent controversy over the efficacy of screening mammography highlights the need for more effective breast imaging techniques. While the sensitivity of mass breast cancer screening with mammography is in the range 60% – 90%, numerous studies have demonstrated that this sensitivity is reduced to less than 50% in radiographically dense breasts. Hence there is need for an alternative screening technique, particularly in women with radiographically dense breasts. A recent ACRIN trial shows that whole breast ultrasound had comparable performance to mammography. Breast MRI performs very well in this population, but high cost and variable specificity limit its application. Conventional scintimammography has a high overall sensitivity and specificity for the detection of breast cancer. However sensitivity drops to ∼50% for the detection of breast lesions less than 15 mm in diameter, making it unsuitable as a diagnostic or screening tool. Molecular Breast Imaging (MBI) refers to a new technique that employs small field of view gamma cameras specifically designed for breast imaging. These cameras utilize either multi‐crystal arrays of Sodium Iodide (NaI) or more recently, use semiconductor materials such as Cadmium‐Zinc‐Telluride (CZT). Using Tc‐99m sestamibi as the primary radiopharmaceutical, MBI has been shown to have a high sensitivity (∼90%) for the detection of breast lesions < 10 mm in diameter. Hence, MBI may be a valuable screening tool, particularly for women in whom the sensitivity of conventional mammography is reduced by the density of the breast parenchyma. This presentation will review the basic principles of molecular breast imaging, and present current clinical results. It will also present details of prototype systems currently under development and future plans for this technology. Learning Objectives: 1. Understand the limitations of current imaging techniques of the breast, including mammography,ultrasound,MRI and scintimammography. 2. Understand the basic concept of multi‐crystal and semiconductor‐based gamma cameras. 3. Describe the relative advantages and disadvantages of scintimammography and molecular breast imaging. 4. Understand the potential advantages/disadvantages and future applications for this technology in the detection and understanding of breast cancer.

An operative gamma camera for sentinel lymph node procedure in case of breast cancer

Large field of view gamma cameras are widely used to perform lymphoscintigraphy in thesentinel lymph nodes (SLN) procedure in case of breast cancer. However, they are not specified for thisapplication and their sizes do not enable their use in the operative room to control the excision of the allSLN. We present the results obtained with a prototype of a new mini gamma camera developed especiallyfor the operative lymphoscintigraphy of the axillary area in case of breast cancer. This prototype iscomposed of 10 mm thick parallel lead collimator, a 2 mm thick GSO:Ce inorganic scintillating crystalfrom Hitachi and a Hamamatsu H8500 flat panel multianode (64 channels) photomultiplier tube(MAPMT) equipped with a dedicated electronics. Its actual field of view is 50 × 50mm2. The gammainteraction position in the GSO scintillating plate is obtained by calculating the center of gravity of thefired MAPMT channels. The measurements performed with this prototype demonstrate the usefulness ofthis mini gamma camera for the pre, per and post-operative identification of SLN's and how itscomplementary role with an intraoperative handheld gamma probe enables to improve the efficiency ofthis practice. A 100 × 100mm2 field of view camera designated to cover the entire axillary area is underinvestigation.

Monte Carlo simulations of compact gamma cameras based on avalanche photodiodes

Avalanche photodiodes (APDs), and in particular position-sensitive avalanche photodiodes (PSAPDs), are an attractive alternative to photomultiplier tubes (PMTs) for reading out scintillators for PET and SPECT. These solid-state devices offer high gain and quantum efficiency, and can potentially lead to more compact and robust imaging systems with improved spatial and energy resolution. In order to evaluate this performance improvement, we have conducted Monte Carlo simulations of gamma cameras based on avalanche photodiodes. Specifically, we investigated the relative merit of discrete and PSAPDs in a simple continuous crystal gamma camera. The simulated camera was composed of either a 4 × 4 array of four channels 8 × 8 mm2 PSAPDs or an 8 × 8 array of 4 × 4 mm2 discrete APDs. These configurations, requiring 64 channels readout each, were used to read the scintillation light from a 6 mm thick continuous CsI:Tl crystal covering the entire 3.6 × 3.6 cm2 photodiode array. The simulations, conducted with GEANT4, accounted for the optical properties of the materials, the noise characteristics of the photodiodes and the nonlinear charge division in PSAPDs. The performance of the simulated camera was evaluated in terms of spatial resolution, energy resolution and spatial uniformity at 99mTc (140 keV) and 125I (≈30 keV) energies. Intrinsic spatial resolutions of 1.0 and 0.9 mm were obtained for the APD- and PSAPD-based cameras respectively for 99mTc, and corresponding values of 1.2 and 1.3 mm FWHM for 125I. The simulations yielded maximal energy resolutions of 7% and 23% for 99mTc and 125I, respectively. PSAPDs also provided better spatial uniformity than APDs in the simple system studied. These results suggest that APDs constitute an attractive technology especially suitable to build compact, small field of view gamma cameras dedicated, for example, to small animal or organ imaging.

Molecular Breast Imaging: Advantages and Limitations of a Scintimammographic Technique in Patients with Small Breast Tumors

Preliminary studies from our laboratory showed that molecular breast imaging (MBI) can reliably detect tumors <2 cm in diameter. This study extends our work to a larger patient population and examines the technical factors that influence the ability of MBI to detect small breast tumors. Following injection of 740 MBq Tc-99m sestamibi, MBI was performed on 100 patients scheduled for biopsy of a lesion suspicious for malignancy that measured <2 cm on mammography or sonography. Using a small field of view gamma camera, patients were imaged in the standard mammographic views using light pain-free compression. Subjective discomfort, breast thickness, the amount of breast tissue in the detector field of view, and breast counts per unit area were measured and recorded. Follow-up was obtained in 99 patients; 53 patients had 67 malignant tumors confirmed at surgery. Of these, 57 of 67 were detected by MBI (sensitivity 85%). Sensitivity was 29%, 86%, and 97% for tumors <5, 6-10, and > or =11 mm in diameter, respectively. In seven patients, MBI identified eight additional mammographically occult tumors. Of 47 patients with no evidence of cancer at biopsy or surgery, there were 36 true negative and 11 false positive scans on MBI. MBI has potential for the regular detection of malignant breast tumors less than 2 cm in diameter. Work in progress to optimize the imaging parameters and technique may further improve sensitivity and specificity.

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Feasibility study on the retention of superporous hydrogel composite polymer in the intestinal tract of man using scintigraphy

In recent years, many complex oral drug delivery systems have been developed using various polymers in order to achieve better drug targeting and drug absorption in the intestinal tract. Superporous hydrogel (SPH) and SPH composite (SPHC)-based drug delivery systems were also developed for the targeted delivery of peptide drugs into the intestinal tract. In the present study, the retention time of SPHC polymer is studied in man using the scintigraphy technique. To that purpose, SPHC polymers were radiolabelled with Tc-99m and administered orally in an enteric-coated gelatin capsule. The location of the radiolabelled polymer was monitored in five healthy volunteers while the subjects were sitting in front of a large field of view gamma camera. The results showed that enteric-coated gelatin capsules remained in the stomach for 75 to 150 min after oral administration to fasted volunteers and that the SPHC polymers thereafter attached to the upper part of the small intestine for at least 45 to 60 min due to their mechanical fixation properties. No discomfort was observed in any of the volunteers after oral administration of these polymers, which indicates that they are safe to be applied for oral drug delivery systems in man.

CdTe and CdZnTe X-ray and gamma-ray detectors for imaging systems

This review paper presents the current state of the art imaging systems using room-temperature CdTe and CdZnTe X-ray and gamma-ray detectors. Imaging systems composed of both single elements and monolithic segmented CdTe and CdZnTe arrays are used in medical diagnostics, astronomy, research and industry. This paper is divided into three sections: The first section describes different types and configurations of CdTe or CdZnTe detectors used in imaging systems, with the emphasis on single charge carrier collection detectors and front-end read-out electronics in the form of Application Specific Integrated Circuits associated with these detectors. The second section discusses the advantages, disadvantages and limitations with respect to the efficiency and area of the imaging systems using CdTe and CdZnTe detectors compared to other types of X and gamma ray detectors. The third section describes several examples of imaging systems utilizing CdZnTe detectors: 1) A large area imaging telescope for the detection of gamma ray bursts using a coded aperture collimator. 2) A large area medical nuclear camera for cardiology and scintimammography using a parallel hole collimator. 3) A large field of view gamma camera based on a rotating slat collimator and 4) A prototype of an electronically collimated Compton camera.