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Sample records for 90y bremsstrahlung spect

  1. MO-G-17A-06: Kernel Based Dosimetry for 90Y Microsphere Liver Therapy Using 90Y Bremsstrahlung SPECT/CT

    SciTech Connect

    Mikell, J; Siman, W; Kappadath, S; Mahvash, A; Mourtada, F

    2014-06-15

    Purpose: 90Y microsphere therapy in liver presents a situation where beta transport is dominant and the tissue is relatively homogenous. We compare voxel-based absorbed doses from a 90Y kernel to Monte Carlo (MC) using quantitative 90Y bremsstrahlung SPECT/CT as source distribution. Methods: Liver, normal liver, and tumors were delineated by an interventional radiologist using contrast-enhanced CT registered with 90Y SPECT/CT scans for 14 therapies. Right lung was segmented via region growing. The kernel was generated with 1.04 g/cc soft tissue for 4.8 mm voxel matching the SPECT. MC simulation materials included air, lung, soft tissue, and bone with varying densities. We report percent difference between kernel and MC (%Δ(K,MC)) for mean absorbed dose, D70, and V20Gy in total liver, normal liver, tumors, and right lung. We also report %Δ(K,MC) for heterogeneity metrics: coefficient of variation (COV) and D10/D90. The impact of spatial resolution (0, 10, 20 mm FWHM) and lung shunt fraction (LSF) (1,5,10,20%) on the accuracy of MC and kernel doses near the liver-lung interface was modeled in 1D. We report the distance from the interface where errors become <10% of unblurred MC as d10(side of interface, dose calculation, FWHM blurring, LSF). Results: The %Δ(K,MC) for mean, D70, and V20Gy in tumor and liver was <7% while right lung differences varied from 60–90%. The %Δ(K,MC) for COV was <4.8% for tumor and liver and <54% for the right lung. The %Δ(K,MC) for D10/D90 was <5% for 22/23 tumors. d10(liver,MC,10,1–20) awere <9mm and d10(liver,MC,20,1–20) awere <15mm; both agreed within 3mm to the kernel. d10(lung,MC,10,20), d10(lung,MC,10,1), d10(lung,MC,20,20), and d10(lung,MC,20,1) awere 6, 25, 15, and 34mm, respectively. Kernel calculations on blurred distributions in lung had errors > 10%. Conclusions: Liver and tumor voxel doses with 90Y kernel and MC agree within 7%. Large differences exist between the two methods in right lung. Research reported in this

  2. Optimization of energy window for {sup 90}Y bremsstrahlung SPECT imaging for detection tasks using the ideal observer with model-mismatch

    SciTech Connect

    Rong Xing; Ghaly, Michael; Frey, Eric C.

    2013-06-15

    Purpose: In yttrium-90 ({sup 90}Y) microsphere brachytherapy (radioembolization) of unresectable liver cancer, posttherapy {sup 90}Y bremsstrahlung single photon emission computed tomography (SPECT) has been used to document the distribution of microspheres in the patient and to help predict potential side effects. The energy window used during projection acquisition can have a significant effect on image quality. Thus, using an optimal energy window is desirable. However, there has been great variability in the choice of energy window due to the continuous and broad energy distribution of {sup 90}Y bremsstrahlung photons. The area under the receiver operating characteristic curve (AUC) for the ideal observer (IO) is a widely used figure of merit (FOM) for optimizing the imaging system for detection tasks. The IO implicitly assumes a perfect model of the image formation process. However, for {sup 90}Y bremsstrahlung SPECT there can be substantial model-mismatch (i.e., difference between the actual image formation process and the model of it assumed in reconstruction), and the amount of the model-mismatch depends on the energy window. It is thus important to account for the degradation of the observer performance due to model-mismatch in the optimization of the energy window. The purpose of this paper is to optimize the energy window for {sup 90}Y bremsstrahlung SPECT for a detection task while taking into account the effects of the model-mismatch. Methods: An observer, termed the ideal observer with model-mismatch (IO-MM), has been proposed previously to account for the effects of the model-mismatch on IO performance. In this work, the AUC for the IO-MM was used as the FOM for the optimization. To provide a clinically realistic object model and imaging simulation, the authors used a background-known-statistically and signal-known-statistically task. The background was modeled as multiple compartments in the liver with activity parameters independently following a

  3. Monte Carlo simulation of PET and SPECT imaging of {sup 90}Y

    SciTech Connect

    Takahashi, Akihiko Sasaki, Masayuki; Himuro, Kazuhiko; Yamashita, Yasuo; Komiya, Isao; Baba, Shingo

    2015-04-15

    Purpose: Yittrium-90 ({sup 90}Y) is traditionally thought of as a pure beta emitter, and is used in targeted radionuclide therapy, with imaging performed using bremsstrahlung single-photon emission computed tomography (SPECT). However, because {sup 90}Y also emits positrons through internal pair production with a very small branching ratio, positron emission tomography (PET) imaging is also available. Because of the insufficient image quality of {sup 90}Y bremsstrahlung SPECT, PET imaging has been suggested as an alternative. In this paper, the authors present the Monte Carlo-based simulation–reconstruction framework for {sup 90}Y to comprehensively analyze the PET and SPECT imaging techniques and to quantitatively consider the disadvantages associated with them. Methods: Our PET and SPECT simulation modules were developed using Monte Carlo simulation of Electrons and Photons (MCEP), developed by Dr. S. Uehara. PET code (MCEP-PET) generates a sinogram, and reconstructs the tomography image using a time-of-flight ordered subset expectation maximization (TOF-OSEM) algorithm with attenuation compensation. To evaluate MCEP-PET, simulated results of {sup 18}F PET imaging were compared with the experimental results. The results confirmed that MCEP-PET can simulate the experimental results very well. The SPECT code (MCEP-SPECT) models the collimator and NaI detector system, and generates the projection images and projection data. To save the computational time, the authors adopt the prerecorded {sup 90}Y bremsstrahlung photon data calculated by MCEP. The projection data are also reconstructed using the OSEM algorithm. The authors simulated PET and SPECT images of a water phantom containing six hot spheres filled with different concentrations of {sup 90}Y without background activity. The amount of activity was 163 MBq, with an acquisition time of 40 min. Results: The simulated {sup 90}Y-PET image accurately simulated the experimental results. PET image is visually

  4. Collimator and energy window optimization for ⁹⁰Y bremsstrahlung SPECT imaging: A SIMIND Monte Carlo study.

    PubMed

    Roshan, Hoda Rezaei; Mahmoudian, Babak; Gharepapagh, Esmaeil; Azarm, Ahmadreza; Islamian, Jalil Pirayesh

    2016-02-01

    Treatment efficacy of radioembolization using Yttrium-90 ((90)Y) microspheres is assessed by the (90)Y bremsstrahlung single photon emission computed tomography (SPECT) imaging following radioembolization. The radioisotopic image has the potential of providing reliable activity map of (90)Y microspheres distribution. One of the main reasons of the poor image quality in (90)Y bremsstrahlung SPECT imaging is the continuous and broad energy spectrum of the related bremsstrahlung photons. Furthermore, collimator geometry plays an impressive role in the spatial resolution, sensitivity and image contrast. Due to the relatively poor quality of the (90)Y bremsstrahlung SPECT images, we intend to optimize the medium-energy (ME) parallel-hole collimator and energy window. The Siemens e.cam gamma camera equipped with a ME collimator and a voxelized phantom was simulated by the SImulating Medical Imaging Nuclear Detectors (SIMIND) program. We used the SIMIND Monte Carlo program to generate the (90)Y bremsstrahlung SPECT projection of the digital Jaszczak phantom. The phantom consist of the six hot spheres ranging from 9.5 to 31.8mm in diameter, which are used to evaluate the image contrast. In order to assess the effect of the energy window on the image contrast, three energy windows ranging from 60 to 160 KeV, 160 to 400 KeV, and 60 to 400 KeV were set on a (90)Y bremsstrahlung spectrum. As well, the effect of the hole diameter of a ME collimator on the image contrast and bremsstrahlung spectrum were investigated. For the fixed collimator and septa thickness values (3.28 cm and 1.14 mm, respectively), a hole diameter range (2.35-3.3mm) was chosen based on the appropriate balance between the spatial resolution and sensitivity. The optimal energy window for (90)Y bremsstrahlung SPECT imaging was extended energy window from 60 to 400 KeV. Besides, The optimal value of the hole diameter of ME collimator was obtained 3.3mm. Geometry of the ME parallel-hole collimator and energy

  5. External bremsstrahlung of 90Sr-90Y, 147Pm and 204Tl in detector compounds

    NASA Astrophysics Data System (ADS)

    Manjunatha, H. C.; Rudraswamy, B.

    2013-04-01

    External Bremsstrahlung spectra produced by the complete absorption of beta particles from 90Sr to 90Y, 147Pm and 204Tl in nuclear radiation detection compounds like Cesium iodide (CsI) and Sodium Iodide (NaI) has been measured using 0.038 m×0.038 m NaI(Tl) crystal and is compared with Tseng-Pratt theory. The Bremsstrahlung yields are calculated using the unfolded spectra. This paper also describes a new procedure for the calculation of effective absorption coefficient of Bremsstrahlung from the Bremsstrahlung spectra. The measured spectra show fairly good agreement at low energy end of spectrum and some deviation at higher energy end of spectrum with the theory. The measured Bremsstrahlung yields may be useful to apply corrections, whenever beta particle passes through CsI and NaI detectors.

  6. Quantitative Comparison of PET and Bremsstrahlung SPECT for Imaging the In Vivo Yttrium-90 Microsphere Distribution after Liver Radioembolization

    PubMed Central

    Elschot, Mattijs; Vermolen, Bart J.; Lam, Marnix G. E. H.; de Keizer, Bart; van den Bosch, Maurice A. A. J.; de Jong, Hugo W. A. M.

    2013-01-01

    Background After yttrium-90 (90Y) microsphere radioembolization (RE), evaluation of extrahepatic activity and liver dosimetry is typically performed on 90Y Bremsstrahlung SPECT images. Since these images demonstrate a low quantitative accuracy, 90Y PET has been suggested as an alternative. The aim of this study is to quantitatively compare SPECT and state-of-the-art PET on the ability to detect small accumulations of 90Y and on the accuracy of liver dosimetry. Methodology/Principal Findings SPECT/CT and PET/CT phantom data were acquired using several acquisition and reconstruction protocols, including resolution recovery and Time-Of-Flight (TOF) PET. Image contrast and noise were compared using a torso-shaped phantom containing six hot spheres of various sizes. The ability to detect extra- and intrahepatic accumulations of activity was tested by quantitative evaluation of the visibility and unique detectability of the phantom hot spheres. Image-based dose estimates of the phantom were compared to the true dose. For clinical illustration, the SPECT and PET-based estimated liver dose distributions of five RE patients were compared. At equal noise level, PET showed higher contrast recovery coefficients than SPECT. The highest contrast recovery coefficients were obtained with TOF PET reconstruction including resolution recovery. All six spheres were consistently visible on SPECT and PET images, but PET was able to uniquely detect smaller spheres than SPECT. TOF PET-based estimates of the dose in the phantom spheres were more accurate than SPECT-based dose estimates, with underestimations ranging from 45% (10-mm sphere) to 11% (37-mm sphere) for PET, and 75% to 58% for SPECT, respectively. The differences between TOF PET and SPECT dose-estimates were supported by the patient data. Conclusions/Significance In this study we quantitatively demonstrated that the image quality of state-of-the-art PET is superior over Bremsstrahlung SPECT for the assessment of the 90Y

  7. Detection of bremsstrahlung radiation of 90Sr-90Y for emergency lung counting.

    PubMed

    Ho, A; Hakmana Witharana, S S; Jonkmans, G; Li, L; Surette, R A; Dubeau, J; Dai, X

    2012-09-01

    This study explores the possibility of developing a field-deployable (90)Sr detector for rapid lung counting in emergency situations. The detection of beta-emitters (90)Sr and its daughter (90)Y inside the human lung via bremsstrahlung radiation was performed using a 3″ × 3″ NaI(Tl) crystal detector and a polyethylene-encapsulated source to emulate human lung tissue. The simulation results show that this method is a viable technique for detecting (90)Sr with a minimum detectable activity (MDA) of 1.07 × 10(4) Bq, using a realistic dual-shielded detector system in a 0.25-µGy h(-1) background field for a 100-s scan. The MDA is sufficiently sensitive to meet the requirement for emergency lung counting of Type S (90)Sr intake. The experimental data were verified using Monte Carlo calculations, including an estimate for internal bremsstrahlung, and an optimisation of the detector geometry was performed. Optimisations in background reduction techniques and in the electronic acquisition systems are suggested.

  8. PET/CT and Bremsstrahlung Imaging After 90Y DOTANOC Therapy for Rectal Net With Liver Metastases.

    PubMed

    Abdülrezzak, Ümmühan; Kula, Mustafa; Tutuş, Ahmet; Buyukkaya, Fikret; Karaca, Halit

    2015-10-01

    Peptide receptor radionuclide therapy with Lu or Y is promising with successful results in somatostatin receptor-positive tumors. In all radiation therapies, knowledge of the radiation dose received by the target, and other organs in the body is essential to evaluate the risks and benefits of any procedure. We report a case of liver metastases from a rectal neuroendocrine tumor, which was treated with Y DOTANOC. Posttreatment whole-body planar images were acquired through Bremsstrahlung radiations of Y on a γ-camera, and thoracolumbar PET/CT images were acquired on PET.

  9. Partition Model-Based 99mTc-MAA SPECT/CT Predictive Dosimetry Compared with 90Y TOF PET/CT Posttreatment Dosimetry in Radioembolization of Hepatocellular Carcinoma: A Quantitative Agreement Comparison.

    PubMed

    Gnesin, Silvano; Canetti, Laurent; Adib, Salim; Cherbuin, Nicolas; Silva Monteiro, Marina; Bize, Pierre; Denys, Alban; Prior, John O; Baechler, Sebastien; Boubaker, Ariane

    2016-11-01

    (90)Y-microsphere selective internal radiation therapy (SIRT) is a valuable treatment in unresectable hepatocellular carcinoma (HCC). Partition-model predictive dosimetry relies on differential tumor-to-nontumor perfusion evaluated on pretreatment (99m)Tc-macroaggregated albumin (MAA) SPECT/CT. The aim of this study was to evaluate agreement between the predictive dosimetry of (99m)Tc-MAA SPECT/CT and posttreatment dosimetry based on (90)Y time-of-flight (TOF) PET/CT.

  10. Clinical impact of (99m)Tc-MAA SPECT/CT-based dosimetry in the radioembolization of liver malignancies with (90)Y-loaded microspheres.

    PubMed

    Garin, Etienne; Rolland, Yan; Laffont, Sophie; Edeline, Julien

    2016-03-01

    Radioembolization with (90)Y-loaded microspheres is increasingly used in the treatment of primary and secondary liver cancer. Technetium-99 m macroaggregated albumin (MAA) scintigraphy is used as a surrogate of microsphere distribution to assess lung or digestive shunting prior to therapy, based on tumoral targeting and dosimetry. To date, this has been the sole pre-therapeutic tool available for such evaluation. Several dosimetric approaches have been described using both glass and resin microspheres in hepatocellular carcinoma (HCC) and liver metastasis. Given that each product offers different specific activities and numbers of spheres injected, their radiobiological properties are believed to lightly differ. This paper summarizes and discusses the available studies focused on MAA-based dosimetry, particularly concentrating on potential confounding factors like clinical context, tumor size, cirrhosis, previous or concomitant therapy, and product used. In terms of the impact of tumoral dose in HCC, the results were concordant and a response relationship and tumoral threshold dose was clearly identified, especially in studies using glass microspheres. Tumoral dose has also been found to influence survival. The concept of treatment intensification has recently been introduced, yet despite several studies publishing interesting findings on the tumor dose-metastasis relationship, no consensus has been reached, and further clarification is thus required. Nor has the maximal tolerated dose to the liver been well documented, requiring more accurate evaluation. Lung dose was well described, despite recently identified factors influencing its evaluation, requiring further assessment. Conclusion: MAA SPECT/CT dosimetry is accurate in HCC and can now be used in order to achieve a fully customized approach, including treatment intensification. Yet further studies are warranted for the metastasis setting and evaluating the maximal tolerated liver dose.

  11. Three-Dimensional Dosimetric Analysis and Quantitative Bremsstrahlung Spect Imaging for Treatment of Non-Resectable Pancreatic Cancer Using Colloidal PHOSPHORUS-32.

    NASA Astrophysics Data System (ADS)

    Parsai, E. Ishmael

    1995-01-01

    Current methods of calculating absorbed dose in tissue from beta emitting radiopharmaceuticals yield only estimates of the average dose and cannot be used for dose mapping of bremsstrahlung SPECT images. The present work describes a clinically applicable methodology that can be used to determine the 3-D absorbed dose distribution from bremsstrahlung SPECT images for patients undergoing infusional brachytherapy. The radiopharmaceutical used in this study was colloidal P-32; however, other beta emitters can be used with this method. Calibration curves were generated from phantom studies to determine the activity per voxel from the attenuation corrected measured counts per voxel. The cumulative activity at each voxel position was converted to dose (Gy) using a Monte Carlo based P -32 point dose kernel calculation in water. Two-dimensional isodose distributions then were generated and projected on the reconstructed SPECT slices. This technique was further extended to calculate the quantitative dose for the entire volume and iso-surface dose distributions were generated in 3-D from bremsstrahlung SPECT data. In addition, to calculate the dose rate or accumulated dose at any depth from a given activity, a computer program based on the modified Loevinger point function was developed. This program calculates the dose in two ways: (1) through a closed solution for the spherical geometry by integration of the function over small spherical volumes, or (2) by applying the revised parameters of the modified Loevinger function. A practical and clinically feasible technique was developed for 3-D image co-registration between CT and SPECT for direct anatomic confirmation of the correlation between the region of the P-32 activity distribution and the anatomic site of injection. The method provides the correlation of the body contours obtained from bremsstrahlung SPECT data with corresponding contours from CT. A 3-D surface was first generated by mapping the iso-counts in the SPECT

  12. Dosimetry of yttrium-labelled radiopharmaceuticals for internal therapy: 86Y or 90Y imaging?

    PubMed

    Walrand, Stephan; Flux, Glenn D; Konijnenberg, Mark W; Valkema, Roelf; Krenning, Eric P; Lhommel, Renaud; Pauwels, Stanislas; Jamar, Francois

    2011-05-01

    This paper reviews issues concerning (86)Y positron emission tomography (PET), (90)Y PET and (90)Y bremsstrahlung imaging. Specific methods and corrections developed for quantitative imaging, for application in preclinical and clinical studies, and to assess (90)Y dosimetry are discussed. The potential imaging capabilities with the radioisotopes (87)Y and (88)Y are also considered. Additional studies required to assess specific unaddressed issues are also identified.

  13. Beta Bremsstrahlung dose in concrete shielding

    NASA Astrophysics Data System (ADS)

    Manjunatha, H. C.; Chandrika, B. M.; Rudraswamy, B.; Sankarshan, B. M.

    2012-05-01

    In a nuclear reactor, beta nuclides are released during nuclear reactions. These betas interact with shielding concrete and produces external Bremsstrahlung (EB) radiation. To estimate Bremsstrahlung dose and shield efficiency in concrete, it is essential to know Bremsstrahlung distribution or spectra. The present work formulated a new method to evaluate the EB spectrum and hence Bremsstrahlung dose of beta nuclides (32P, 89Sr, 90Sr-90Y, 90Y, 91Y, 208Tl, 210Bi, 234Pa and 40K) in concrete. The Bremsstrahlung yield of these beta nuclides in concrete is also estimated. The Bremsstrahlung yield in concrete due to 90Sr-90Y is higher than those of other given nuclides. This estimated spectrum is accurate because it is based on more accurate modified atomic number (Zmod) and Seltzer's data, where an electron-electron interaction is also included. Presented data in concrete provide a quick and convenient reference for radiation protection. The present methodology can be used to calculate the Bremsstrahlung dose in nuclear shielding materials. It can be quickly employed to give a first pass dose estimate prior to a more detailed experimental study.

  14. [Studies of biologic activation associated with molecular receptor increase and tumor response in ChL6/L6 protocol patients; Studies in phantoms; Quantitative SPECT; Preclinical studies; and Clinical studies]. DOE annual report, 1994--95

    SciTech Connect

    DeNardo, S.J.

    1995-12-31

    The authors describe results which have not yet been published from their associated studies listed in the title. For the first, they discuss Lym-1 single chain genetically engineered molecules, analysis of molecular genetic coded messages to enhance tumor response, and human dosimetry and therapeutic human use radiopharmaceuticals. Studies in phantoms includes a discussion of planar image quantitation, counts coincidence correction, organ studies, tumor studies, and {sup 90}Y quantitation with Bremsstrahlung imaging. The study on SPECT discusses attenuation correction and scatter correction. Preclinical studies investigated uptake of {sup 90}Y-BrE-3 in mice using autoradiography. Clinical studies discuss image quantitation verses counts from biopsy samples, S factors for radiation dose calculation, {sup 67}Cu imaging studies for lymphoma cancer, and {sup 111}In MoAb imaging studies for breast cancer to predict {sup 90}Y MoAb therapy.

  15. 3D dosimetry estimation for selective internal radiation therapy (SIRT) using SPECT/CT images: a phantom study

    NASA Astrophysics Data System (ADS)

    Debebe, Senait A.; Franquiz, Juan; McGoron, Anthony J.

    2015-03-01

    Selective Internal Radiation Therapy (SIRT) is a common way to treat liver cancer that cannot be treated surgically. SIRT involves administration of Yttrium - 90 (90Y) microspheres via the hepatic artery after a diagnostic procedure using 99mTechnetium (Tc)-macroaggregated albumin (MAA) to detect extrahepatic shunting to the lung or the gastrointestinal tract. Accurate quantification of radionuclide administered to patients and radiation dose absorbed by different organs is of importance in SIRT. Accurate dosimetry for SIRT allows optimization of dose delivery to the target tumor and may allow for the ability to assess the efficacy of the treatment. In this study, we proposed a method that can efficiently estimate radiation absorbed dose from 90Y bremsstrahlung SPECT/CT images of liver and the surrounding organs. Bremsstrahlung radiation from 90Y was simulated using the Compton window of 99mTc (78keV at 57%). 99mTc images acquired at the photopeak energy window were used as a standard to examine the accuracy of dosimetry prediction by the simulated bremsstrahlung images. A Liqui-Phil abdominal phantom with liver, stomach and two tumor inserts was imaged using a Philips SPECT/CT scanner. The Dose Point Kernel convolution method was used to find the radiation absorbed dose at a voxel level for a three dimensional dose distribution. This method will allow for a complete estimate of the distribution of radiation absorbed dose by tumors, liver, stomach and other surrounding organs at the voxel level. The method provides a quantitative predictive method for SIRT treatment outcome and administered dose response for patients who undergo the treatment.

  16. Posttherapy radiation safety considerations in radiomicrosphere treatment with 90Y-microspheres.

    PubMed

    Gulec, Seza A; Siegel, Jeffry A

    2007-12-01

    Radiomicrosphere treatment involves the intrahepatic arterial administration of (90)Y-resin or (90)Y-glass microspheres. The microspheres are biocompatible, but not biodegradable, and little to no (90)Y leaches from the microspheres. Without any bioelimination, the beta-dose delivery is generally confined to the liver. Although U.S. Nuclear Regulatory Commission requirements permit patients treated with these microspheres to be released without the need for dose determination or patient instructions, there are important radiation safety issues that need scientific clarification. We carefully evaluated the radiation exposure mechanisms, including the bremsstrahlung radiation doses to others, for a variety of lifestyle behaviors. Dose estimates were also made for several practical and theoretic situations involving the patient's gonads, an embryo or fetus, and a nursing infant. For the infant, we evaluated the potential beta-dose that might be introduced via breast milk ingestion. The bremsstrahlung component of the decay scheme of the pure beta-emitter (90)Y has traditionally been ignored in internal and external dose calculations. Because the production of in vivo bremsstrahlung with the high-energy pure beta-particle-emitting radionuclides used for therapeutic purposes is sufficient to permit external detection and imaging, we believe that the contribution of such radiation should be considered with regard to patient release; we therefore chose to evaluate this potential external radiation hazard. In all cases, the estimated doses were very small, indicating that no patient restrictions are required for radiation safety purposes after the release of a patient who has been treated with (90)Y-microspheres.

  17. (90)Y Radioembolization: Multimodality Imaging Pattern Approach with Angiographic Correlation for Optimized Target Therapy Delivery.

    PubMed

    Camacho, Juan C; Moncayo, Valeria; Kokabi, Nima; Reavey, Hamilton E; Galt, James R; Yamada, Kei; Kies, Darren D; Williams, Roger S; Kim, Hyun S; Schuster, David M

    2015-01-01

    Primary and metastatic liver cancers are responsible for considerable morbidity and mortality, and many patients are not curable at presentation. Therefore, new therapies such as radioembolization with yttrium 90 ((90)Y)-labeled microspheres are an alternative method to treat patients with unresectable primary or secondary liver tumors. Patient selection, treatment technique, and early recognition of potential complications are the keys for successful patient outcomes. The activity of administered (90)Y microspheres depends on multiple variables, including the tumor burden, the volume of the liver lobe to be treated, the type of (90)Y microspheres, and the hepatopulmonary shunt fraction. Preprocedural planning relies on the results of cross-sectional imaging to determine the extent of disease, tumoral and nontumoral liver volumes, patency of the portal vein, and the degree of extrahepatic disease. A multidisciplinary approach that combines expertise in cross-sectional imaging, nuclear medicine, and flow dynamics is critical to adequately target malignant tissue. Preprocedural multimodality imaging, particularly combined single photon emission computed tomography (SPECT) and computed tomography (CT) imaging (SPECT/CT), may be used to identify nontarget imaging patterns that, if recognized, can potentially be corrected with either branch vessel embolization or catheter repositioning. Postprocedural multimodality imaging is also useful to confirm the appropriate delivery of (90)Y microspheres, enabling early identification of potential complications and the adequacy of microsphere distribution, thereby optimizing planning for subsequent therapies.

  18. Patient dosimetry for 90Y selective internal radiation treatment based on 90Y PET imaging.

    PubMed

    Ng, Sherry C; Lee, Victor H; Law, Martin W; Liu, Rico K; Ma, Vivian W; Tso, Wai Kuen; Leung, To Wai

    2013-09-06

    Until recently, the radiation dose to patients undergoing the 90Y selective internal radiation treatment (SIRT) procedure is determined by applying the partition model to 99mTc MAA pretreatment scan. There can be great uncertainty in radiation dose calculated from this approach and we presented a method to compute the 3D dose distributions resulting from 90Y SIRT based on 90Y positron emission tomography (PET) imaging. Five 90Y SIRT treatments were retrospectively analyzed. After 90Y SIRT, patients had 90Y PET/CT imaging within 6 hours of the procedure. To obtain the 3D dose distribution of the patients, their respective 90Y PET images were convolved with a Monte Carlo generated voxel dose kernel. The sensitivity of the PET/CT scanner for 90Y was determined through phantom studies. The 3D dose distributions were then presented in DICOM RT dose format. By applying the linear quadratic model to the dose data, we derived the biologically effective dose and dose equivalent to 2 Gy/fraction delivery, taking into account the spatial and temporal dose rate variations specific for SIRT. Based on this data, we intend to infer tumor control probability and risk of radiation induced liver injury from SIRT by comparison with established dose limits. For the five cases, the mean dose to target ranged from 51.7 ± 28.6 Gy to 163 ± 53.7 Gy. Due to the inhomogeneous nature of the dose distribution, the GTVs were not covered adequately, leading to very low values of tumor control probability. The mean dose to the normal liver ranged from 21.4 ± 30.7 to 36.7 ± 25.9 Gy. According to QUANTEC recommendation, a patient with primary liver cancer and a patient with metastatic liver cancer has more than 5% risk of radiotherapy-induced liver disease (RILD).

  19. Administration guidelines for radioimmunotherapy of non-Hodgkin's lymphoma with (90)Y-labeled anti-CD20 monoclonal antibody.

    PubMed

    Wagner, Henry N; Wiseman, Gregory A; Marcus, Carol S; Nabi, Hani A; Nagle, Conrad E; Fink-Bennett, Darlene M; Lamonica, Dominick M; Conti, Peter S

    2002-02-01

    90Y-ibritumomab tiuxetan is a novel radioimmunotherapeutic agent recently approved for the treatment of relapsed or refractory low-grade, follicular, or CD20+ transformed non-Hodgkin's lymphoma (NHL). (90)Y-ibritumomab tiuxetan consists of a murine monoclonal antibody covalently attached to a metal chelator, which stably chelates (111)In for imaging and (90)Y for therapy. Both health care workers and patients receiving this therapy need to become familiar with how it differs from conventional chemotherapy and what, if any, safety precautions are necessary. Because (90)Y is a pure beta-emitter, the requisite safety precautions are not overly burdensome for health care workers or for patients and their families. (90)Y-ibritumomab tiuxetan is dosed on the basis of the patient's body weight and baseline platelet count; dosimetry is not required for determining the therapeutic dose in patients meeting eligibility criteria similar to those used in clinical trials, such as <25% lymphomatous involvement of the bone marrow. (111)In- and (90)Y-ibritumomab tiuxetan are labeled at commercial radiopharmacies and delivered for on-site dose preparation and administration. Plastic and acrylic materials are appropriate for shielding during dose preparation and administration; primary lead shielding should be avoided because of the potential exposure risk from bremsstrahlung. Because there are no penetrating gamma-emissions associated with the therapy, (90)Y-ibritumomab tiuxetan is routinely administered on an outpatient basis. Furthermore, the risk of radiation exposure to patients' family members has been shown to be in the range of background radiation, even without restrictions on contact. There is therefore no need to determine activity limits or dose rate limits before patients who have been treated with (90)Y radioimmunotherapy are released, as is necessary with patients who have been treated with radiopharmaceuticals that contain (131)I. Standard universal precautions for

  20. D-brane bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Bachlechner, Thomas C.; McAllister, Liam

    2013-10-01

    We study the dynamics of ultrarelativistic D-branes. The dominant phenomenon is bremsstrahlung: mild acceleration induced by closed string interactions triggers extremely rapid energy loss through radiation of massless closed strings. After characterizing bremsstrahlung from a general k-dimensional extended object in a D-dimensional spacetime, we incorporate effects specific to D-branes, including velocity-dependent forces and open string pair creation. We then show that dissipation due to bremsstrahlung can substantially alter the dynamics in DBI inflation.

  1. PET optimization for improved assessment and accurate quantification of {sup 90}Y-microsphere biodistribution after radioembolization

    SciTech Connect

    Martí-Climent, Josep M. Prieto, Elena; Elosúa, César; Rodríguez-Fraile, Macarena; Domínguez-Prado, Inés; Vigil, Carmen; García-Velloso, María J.; Arbizu, Javier; Peñuelas, Iván; Richter, José A.

    2014-09-15

    Purpose: {sup 90}Y-microspheres are widely used for the radioembolization of metastatic liver cancer or hepatocellular carcinoma and there is a growing interest for imaging {sup 90}Y-microspheres with PET. The aim of this study is to evaluate the performance of a current generation PET/CT scanner for {sup 90}Y imaging and to optimize the PET protocol to improve the assessment and the quantification of {sup 90}Y-microsphere biodistribution after radioembolization. Methods: Data were acquired on a Biograph mCT-TrueV scanner with time of flight (TOF) and point spread function (PSF) modeling. Spatial resolution was measured with a{sup 90}Y point source. Sensitivity was evaluated using the NEMA 70 cm line source filled with {sup 90}Y. To evaluate the count rate performance, {sup 90}Y vials with activity ranging from 3.64 to 0.035 GBq were measured in the center of the field of view (CFOV). The energy spectrum was evaluated. Image quality with different reconstructions was studied using the Jaszczak phantom containing six hollow spheres (diameters: 31.3, 28.1, 21.8, 16.1, 13.3, and 10.5 mm), filled with a 207 kBq/ml {sup 90}Y concentration and a 5:1 sphere-to-background ratio. Acquisition time was adjusted to simulate the quality of a realistic clinical PET acquisition of a patient treated with SIR-Spheres{sup ®}. The developed methodology was applied to ten patients after SIR-Spheres{sup ®} treatment acquiring a 10 min per bed PET. Results: The energy spectrum showed the{sup 90}Y bremsstrahlung radiation. The {sup 90}Y transverse resolution, with filtered backprojection reconstruction, was 4.5 mm in the CFOV and degraded to 5.0 mm at 10 cm off-axis. {sup 90}Y absolute sensitivity was 0.40 kcps/MBq in the center of the field of view. Tendency of true and random rates as a function of the {sup 90}Y activity could be accurately described using linear and quadratic models, respectively. Phantom studies demonstrated that, due to low count statistics in {sup 90}Y PET

  2. Inflammation-induced synergetic enhancement of nanoparticle treatments with DOXIL® and 90Y-Lactosome for orthotopic mammary tumor

    NASA Astrophysics Data System (ADS)

    Kurihara, Kensuke; Ueda, Motoki; Hara, Isao; Hara, Eri; Sano, Kohei; Makino, Akira; Ozeki, Eiichi; Yamamoto, Fumihiko; Saji, Hideo; Togashi, Kaori; Kimura, Shunsaku

    2016-05-01

    Polymeric micelles (Lactosome) in the size of 20-30 nm were labeled with radionuclides of 111In (111In-DOTA-Lactosome) for SPECT imaging and 90Y (90Y-DOTA-Lactosome) for β-ray irradiation for mammary tumor in mice. The tumor site at the femoral right leg grafted with 4T1 cells was clearly imaged at 24 h after the intravenous injection. Biodistribution revealed that the half-life time of 111In-DOTA-Lactosome was 11 h, which enabled the nanoparticle selectively accumulated in tumor site due to the enhanced permeability and retention (EPR) effect. The anti-tumor therapeutic effect of 90Y-DOTA-Lactosome was observed depending on the dose frequency and amount. Under the condition of the percutaneous ethanol injection treatment, the therapeutic effect of 90Y-DOTA-Lactosome was enhanced due to the super EPR effect. Owing to the super EPR effect, co-administration of 90Y-DOTA-Lactosome and DOXIL® inhibited the tumor growth during 15 days with their administrations.

  3. Electron - Atom Bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Kim, Longhuan

    In this work we study the features of bremsstrahlung radiation from neutral atoms and atoms in hot dense plasmas. Predictions for the distributions of electron-atom bremsstrahlung radiation for both the point Coulomb potential and screened potentials are obtained using a classical numerical method. The results agree with exact quantum mechanical partial wave results for low incident electron energies in both the point Coulomb and screened potentials. In the screened potential the asymmetry parameter of a spectrum is reduced from the Coulomb values. The difference increases with decreasing energy and begins to oscillate at very low energies. We also studied the scaling properties of bremsstrahlung spectra and energy losses. It is found that the ratio of the radiative energy loss for positrons to that for electrons obeys a simple scaling law, being expressible fairly accurately as a function only of the quantity T(,1)/Z('2). This scaling is exact in the case of the point Coulomb potential, both for classical bremsstrahlung and for the nonrelativistic dipole Sommerfeld formula. We also studied bremsstrahlung from atoms in hot dense plasmas, describing the atomic potentials by the temperature-and-density dependent Thomas - Fermi model. Gaunt factors are obtained with the relativistic partial wave method for atoms in plasmas of various densities and temperatures. Features of the bremsstrahlung from atoms in such environments are discussed. The dependence of predicted bremsstrahlung spectra on the choice of potential from various average atom potential models for strongly coupled plasmas are also studied. For the energy range and plasma densities were considered, the choice of potential model among the elaborate atomic potentials is less important than the choice of the method of calculation. The use of a detailed configuration accounting method for bremsstrahlung processes in dense plasmas is less important than for some other atomic processes. We justify the usefulness

  4. 90 Y-ibritumomab tiuxetan: a nearly forgotten opportunity

    PubMed Central

    Mondello, Patrizia; Cuzzocrea, Salvatore; Navarra, Michele; Mian, Michael

    2016-01-01

    Y-ibritumomab tiuxetan (90Y-IT) combines the benefits of a monoclonal antibody with the efficacy of radiation in the treatment of B-cell non-Hodgkin lymphoma (NHL), a remarkably radiosensitive hematologic malignancy. 90Y-IT activity has been well established in the indolent setting, being approved in front-line treatment of follicular lymphoma (FL) patients as well as salvage therapy. However, no advantage in OS was observed with respect to standard treatment. Promising data are available also for aggressive B-cell lymphoma. In particular, the addition of RIT to short-course first line chemotherapy enables reduction of chemotherapy while maintaining cure rates in elderly, untreated diffuse large B-cell lymphoma (DLBCL) patients. Furthermore, 90Y-IT improves response rate and outcomes of relapsed/refractory DLBCL patients, eligible and ineligible for autologous stem cell transplantation (ASCT). Clinical results have shown a role of 90Y-IT even in mantle cell lymphoma (MCL). RIT might improve responses and treat minimal residual disease when used as consolidation after first-line chemotherapy in MCL. Moreover, 90Y-IT has demonstrated its efficacy in combination with high-dose chemotherapies as conditioning regimen for ASCT, with evidence suggesting the ability to overcome chemotherapy resistance. Herein, we review the available evidence for this approved drug and examine the recently published and ongoing trials for potential novel indication in aggressive B-cell NHL. PMID:26657116

  5. Purification and uses of /sup 90/Y for medical research

    SciTech Connect

    Wike, J.S.; Haff, K.W.; Phillips, B.P.

    1985-11-01

    Medical researchers are utilizing two new products recently developed for a new attack on some forms of human cancer. One development in the early 1980s was the monoclonal antibody. A second product for liver cancer therapy is being developed. A radioactive isotope must meet rigid criteria to be used for labeling of these products. It must have a short half-life (days), be free of other long-lived radionuclides, and emit rays with energy that have a short path length in flesh. One isotope that meets these criteria is /sup 90/Y, which is the decay daughter of /sup 90/Sr. It has a 63.4-h half-life, a 2.25-MeV beta energy with no gamma energy, and decays to stable /sup 90/Zr. When /sup 90/Y is to be used with human patients, it is necessary to remove the /sup 90/Sr precursor to the lowest possible levels. A 50-Ci strontium cow was prepared at the Oak Ridge National Laboratory (ORNL) for the production of ultra-pure /sup 90/Y chloride. This cow was placed in a remote cell with master/slave manipulators for processing the /sup 90/Y. No other radionuclides are processed in this cell, thus eliminating the possibility of contamination of the finished product with alpha- and gamma-emitting nuclides. The 50-Ci source of /sup 90/Sr was selected for the production of /sup 90/Y in multicurie quantities. Large quantities of /sup 90/Y will be needed if research programs demonstrate that it is effective in the treatment of cancer.

  6. Monte Carlo dosimetry of a new 90Y brachytherapy source

    PubMed Central

    Junxiang, Wu; Shihu, You; Jing, Huang; Fengxiang, Long; Chengkai, Wang; Zhangwen, Wu; Qing, Hou

    2015-01-01

    Purpose In this study, we attempted to obtain full dosimetric data for a new 90Y brachytherapy source developed by the College of Chemistry (Sichuan University) for use in high-dose-rate after-loading systems. Material and methods The dosimetric data for this new source were used as required by the dose calculation formalisms proposed by the AAPM Task Group 60 and Task Group 149. The active core length of the new 90Y source was increased to 4.7 mm compared to the value of 2.5 mm for the old 90Sr/90Y source. The Monte Carlo simulation toolkit Geant4 was used to calculate these parameters. The source was located in a 30-cm-radius theoretical sphere water phantom. Results The dosimetric data included the reference absorbed dose rate, the radial dose function in the range of 1.0 to 8.0 mm in the longitudinal axis, and the anisotropy function with a θ in the range of 0° to 90° at 5° intervals and an r in the range of 1.0 to 8.0 mm in 0.2-mm intervals. The reference absorbed dose rate for the new 90Y source was determined to be equal to 1.6608 ± 0.0008 cGy s–1 mCi–1, compared to the values of 0.9063 ± 0.0005 cGy s–1 mCi–1 that were calculated for the old 90Sr/90Y source. A polynomial function was also obtained for the radial dose function by curve fitting. Conclusions Dosimetric data are provided for the new 90Y brachytherapy source. These data are meant to be used commercially in after-loading system. PMID:26622247

  7. Beta spectra of /sup 90/Sr and /sup 90/Y

    SciTech Connect

    Devaney, J.J.

    1985-08-01

    Using as a base the beta energy spectra provided by T.R. England, the number spectra of /sup 90/Sr and /sup 90/Y were corrected for the Coulomb effects on the first forbidden shape factor using the tables of M.E. Rose, and for higher order effects using the experimentally determined corrections of H. Daniel et al. We, therefore, present a fully corrected beta number spectrum of /sup 90/Sr and its daughter /sup 90/Y. The half-lives and end-point energies are also listed.

  8. Runaway electrons and Bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Helander, Per

    2016-09-01

    If an electric field is applied to a plasma, it causes ‘runaway’ acceleration of some electrons—a phenomenon that has been known for almost a century. A paper by Embréus et al (2016 New J. Phys. 18 093023) calculates how the emission of Bremsstrahlung affects the upper end of the energy spectrum of these electrons, and finds that it is important to carefully account for finite energy of the emitted photons.

  9. A computational tool for patient specific dosimetry and radiobiological modeling of selective internal radiation therapy with (90)Y microspheres.

    PubMed

    Kalantzis, Georgios; Leventouri, Theodora; Apte, Aditiya; Shang, Charles

    2015-11-01

    In recent years we have witnessed tremendous progress in selective internal radiation therapy. In clinical practice, quite often, radionuclide therapy is planned using simple models based on standard activity values or activity administered per unit body weight or surface area in spite of the admission that radiation-dose methods provide more accurate dosimetric results. To address that issue, the authors developed a Matlab-based computational software, named Patient Specific Yttrium-90 Dosimetry Toolkit (PSYDT). PSYDT was designed for patient specific voxel-based dosimetric calculations and radiobiological modeling of selective internal radiation therapy with (90)Y microspheres. The developed toolkit is composed of three dimensional dose calculations for both bremsstrahlung and beta emissions. Subsequently, radiobiological modeling is performed on a per-voxel basis and cumulative dose volume histograms (DVHs) are generated. In this report we describe the functionality and visualization features of PSYDT.

  10. Bremsstrahlung from cylindrical beta sources.

    NASA Technical Reports Server (NTRS)

    Harris, D. W.; Silverman, J.

    1972-01-01

    Refined experimental measurements of the bremsstrahlung number and energy fluxes from thick cylindrical sources of several nuclides are presented, dose rates calculated from experimental energy fluxes are compared with theoretical results based on Wyard's thick-target approximation, and experiments are correlated with both thick- and thin-target bremsstrahlung theory to obtain accurate values of bremsstrahlung yields. The data presented should prove useful for the design of radioisotope power supplies, particularly those used in spacecraft and in biological applications.

  11. 90Y-Edotreotide for Metastatic Carcinoid Refractory to Octreotide

    PubMed Central

    Bushnell, David L.; O'Dorisio, Thomas M.; O'Dorisio, M. Sue; Menda, Yusuf; Hicks, Rodney J.; Van Cutsem, Eric; Baulieu, Jean-Louis; Borson-Chazot, Francoise; Anthony, Lowell; Benson, Al B.; Oberg, Kjell; Grossman, Ashley B.; Connolly, Mary; Bouterfa, Hakim; Li, Yong; Kacena, Katherine A.; LaFrance, Norman; Pauwels, Stanislas A.

    2010-01-01

    Purpose Metastatic carcinoid is an incurable malignancy whose symptoms, such as diarrhea and flushing, can be debilitating and occasionally life-threatening. Although symptom relief is available with octreotide, the disease eventually becomes refractory to octreotide, leaving no proven treatment options. The goal of this study was to evaluate the clinical effect of using 90Y-edotreotide to treat symptomatic patients with carcinoid tumors. Patients and Methods Patients enrolled had metastatic carcinoid, at least one sign/symptom refractory to octreotide, and at least one measurable lesion. Study treatment consisted of three cycles of 4.4 GBq (120 mCi) 90Y-edotreotide each, once every 6 weeks. Results Ninety patients were enrolled in the study. Using Southwest Oncology Group tumor response criteria, 67 (74.%) of 90 patients (95% CI, 65.4% to 83.4%) were objectively stable or responded. A statistically significant linear trend toward improvement was demonstrated across all 12 symptoms assessed. Median progression-free survival was significantly greater (P = .03) for the 38 patients who had durable diarrhea improvement than the 18 patients who did not (18.2 v 7.9 months, respectively). Adverse events (AEs) were reported in 96.7% (87 of 90) of patients. These AEs consisted primarily of reversible GI events (76 of 90), which could be caused in part by concomitant administration of amino acid solution given to reduce radiation exposure to the kidneys. There was one case each of grade 3 oliguria and grade 4 renal failure, each lasting 6 days. Conclusion 90Y-edotreotide treatment improved symptoms associated with malignant carcinoid among subjects with no treatment alternatives. Treatment was well-tolerated and had an acceptable expected AE profile. PMID:20194865

  12. Adaptive SPECT

    PubMed Central

    Barrett, Harrison H.; Furenlid, Lars R.; Freed, Melanie; Hesterman, Jacob Y.; Kupinski, Matthew A.; Clarkson, Eric; Whitaker, Meredith K.

    2008-01-01

    Adaptive imaging systems alter their data-acquisition configuration or protocol in response to the image information received. An adaptive pinhole single-photon emission computed tomography (SPECT) system might acquire an initial scout image to obtain preliminary information about the radiotracer distribution and then adjust the configuration or sizes of the pinholes, the magnifications, or the projection angles in order to improve performance. This paper briefly describes two small-animal SPECT systems that allow this flexibility and then presents a framework for evaluating adaptive systems in general, and adaptive SPECT systems in particular. The evaluation is in terms of the performance of linear observers on detection or estimation tasks. Expressions are derived for the ideal linear (Hotelling) observer and the ideal linear (Wiener) estimator with adaptive imaging. Detailed expressions for the performance figures of merit are given, and possible adaptation rules are discussed. PMID:18541485

  13. Three dosimetry models of lipoma arborescens treated by {sup 90}Y synovectomy

    SciTech Connect

    O’Doherty, Jim; Clauss, Ralf; Scuffham, James; Khan, Aman; Petitguillaume, Alice; Desbrée, Aurélie

    2014-05-15

    Purpose: Lipoma arborescens (LA) is a benign intra-articular lipomatous proliferation of the synovial membrane. This extremely rare condition has previously been treated by intra-articular{sup 90}Y radiosynoviorthesis but dosimetry literature on this form of radionuclide therapy is nonexistent. The authors detail methodology for successful treatment of LA and provide for the first time estimates of radiation dosimetry. The authors also analyze the biodistribution of the radiopharmaceutical over the course of the patient's treatment through sequential imaging. Methods: A patient with bilateral LA underwent intracavity injection of{sup 90}Y citrate colloid to the right and left knee joint spaces (181 and 198 MBq, respectively). SPECT/CT datasets were acquired over 9 days to quantify the biodistribution and kinetics of the radiopharmaceutical. Radiation dosimetry was performed using the MIRD schema (through OLINDA software), a custom voxel-based method, and a direct Monte Carlo calculation (OEDIPE). Results: Follow-up MRI showed marked reduction in LA size in both knees. Mean absorbed doses to the LA were 21.2 ± 0.8 and 42.9 ± 2.3 Gy using OLINDA, 8.1 ± 0.3 and 16.7 ± 0.5 Gy using voxel based methodology, and 8.2 ± 0.3 and 15.7 ± 0.5 Gy for OEDIPE in the right and left LA, respectively. Distribution of the radiopharmaceutical within the joint space alters over the imaging period, with less than 1% of the remaining activity having moved posteriorly in the knee cavity. No uptake was detected outside of the joint space after assessment with whole-body scintigraphy. Conclusions: An activity of approximately 185 MBq successfully relieved clinical symptoms of LA. There was good correlation between direct Monte Carlo and voxel based techniques, but OLINDA was shown to overestimate the absorbed dose to the tumor. Accurate dosimetry may help select an activity more tailored to the specific size and location of the LA.

  14. Determination of 90Sr traces in medical 90Y after separation on DGA column.

    PubMed

    Pawlak, Dariusz W; Parus, Jozef L; Dziel, Tomasz; Muklanowicz, Anna; Mikolajczak, Renata

    2013-09-30

    A new analytical procedure for (90)Sr determination in freshly milked (90)Y from a (90)Sr/(90)Y generator is described. To a solution containing 125 mg of Sr a 200 to 400 MBq sample of (90)Y is added and strontium is separated from (90)Y using DGA column of 1 mL volume. (90)Sr is recovered in a yield close to 100% and counted in a liquid scintillation spectrometer (LSC). The separated strontium is slightly contaminated with (90)Y in the range from 7 to 19% of (90)Sr activity. The separation and counting can be completed within 30 min. The detection limit in 900 s counting time is equal to about 0.2 Bq. This corresponds to (90)Sr/(90)Y activity ratio of 10(-8) level.

  15. Hanford isotope project strategic business analysis yttrium-90 (Y-90)

    SciTech Connect

    1995-10-01

    The purpose of this analysis is to address the short-term direction for the Hanford yttrium-90 (Y-90) project. Hanford is the sole DOE producer of Y-90, and is the largest repository for its source in this country. The production of Y-90 is part of the DOE Isotope Production and Distribution (IP and D) mission. The Y-90 is ``milked`` from strontium-90 (Sr-90), a byproduct of the previous Hanford missions. The use of Sr-90 to produce Y-90 could help reduce the amount of waste material processed and the related costs incurred by the clean-up mission, while providing medical and economic benefits. The cost of producing Y-90 is being subsidized by DOE-IP and D due to its use for research, and resultant low production level. It is possible that the sales of Y-90 could produce full cost recovery within two to three years, at two curies per week. Preliminary projections place the demand at between 20,000 and 50,000 curies per year within the next ten years, assuming FDA approval of one or more of the current therapies now in clinical trials. This level of production would incentivize private firms to commercialize the operation, and allow the government to recover some of its sunk costs. There are a number of potential barriers to the success of the Y-90 project, outside the control of the Hanford Site. The key issues include: efficacy, Food and Drug Administration (FDA) approval and medical community acceptance. There are at least three other sources for Y-90 available to the US users, but they appear to have limited resources to produce the isotope. Several companies have communicated interest in entering into agreements with Hanford for the processing and distribution of Y-90, including some of the major pharmaceutical firms in this country.

  16. Recurrent villonodular synovitis of the knee. Successful treatment with /sup 90/Y

    SciTech Connect

    Wiss, D.A.

    1982-09-01

    A 40-year-old woman with recurrent pigmented villonodular synovitis of the knee was treated with /sup 90/Y radiocolloid. The advantages of /sup 90/Y include effectiveness, low cost, simplicity, and low morbidity. The radiophysical properties of /sup 90/Y that make it a useful therapeutic agent are short half-life, pure beta emission and good penetration of the soft tissues. Side effects are few, predictable, and for the most part, avoidable. Radionecrosis of soft tissue, needle tract pigmentation, injection site tenderness, pyrexia, and lymphocyte chromosomal abnormalities have been reported. The indications for intra-articular radiocolloid therapy are the same as for surgical synovectomy, except that it is reserved for patients older than 35 years of age. The pathologic events following /sup 90/Y therapy in experimental animals show coagulation necrosis of the synovium, followed by an intense inflammatory reaction, leading ultimately to fibrosis. /sup 90/Y is a useful adjuvant in the treatment of recurrent pigmented villonodular synovitis.

  17. Inverse Bremsstrahlung in Shocked Astrophysical Plasmas

    NASA Technical Reports Server (NTRS)

    Baring, Matthew G.; Jones, Frank C.; Ellison, Donald C.

    2000-01-01

    There has recently been interest in the role of inverse bremsstrahlung, the emission of photons by fast suprathermal ions in collisions with ambient electrons possessing relatively low velocities, in tenuous plasmas in various astrophysical contexts. This follows a long hiatus in the application of suprathermal ion bremsstrahlung to astrophysical models since the early 1970s. The potential importance of inverse bremsstrahlung relative to normal bremsstrahlung, i.e. where ions are at rest, hinges upon the underlying velocity distributions of the interacting species. In this paper, we identify the conditions under which the inverse bremsstrahlung emissivity is significant relative to that for normal bremsstrahlung in shocked astrophysical plasmas. We determine that, since both observational and theoretical evidence favors electron temperatures almost comparable to, and certainly not very deficient relative to proton temperatures in shocked plasmas, these environments generally render inverse bremsstrahlung at best a minor contributor to the overall emission. Hence inverse bremsstrahlung can be safely neglected in most models invoking shock acceleration in discrete sources such as supernova remnants. However, on scales approximately > 100 pc distant from these sources, Coulomb collisional losses can deplete the cosmic ray electrons, rendering inverse bremsstrahlung, and perhaps bremsstrahlung from knock-on electrons, possibly detectable.

  18. Attenuation of external Bremsstrahlung in metallic absorbers

    SciTech Connect

    Dhaliwal, A.S.; Powar, M.S.; Singh, M. )

    1990-12-01

    In this paper attenuation of bremsstrahlung from {sup 147}Pm and {sup 170}Tm beta emitters has been studied in aluminum, copper, tin, and lead metallic absorbers. Bremsstrahlung spectra and mass attenuation coefficients for monoenergetic gamma rays are used to calculate theoretical attenuation curves. Magnetic deflection and beta stopping techniques are used to measure the integral bremsstrahlung intensities above 30 keV in different target thicknesses. Comparison of measured and calculated attenuation curves shows a good agreement for various absorbers, thus providing a test of this technique, which may be useful in understanding bremsstrahlung intensity buildup and in the design of optimum shielding for bremsstrahlung sources. It is found that the absorption of bremsstrahlung in metallic absorbers does not obey an exponential law and that absorbers act as energy filters.

  19. 90Y. B72. 3 against pancreatic cancer: Dosimetric and biological analysis

    SciTech Connect

    Mehta, M.P.; Kubsad, S.S.; Fowler, J.F.; Verma, A.K.; Hsieh, J.T.; Kinsella, T.J. )

    1990-09-01

    Nude mice xenografted with a human pancreatic carcinoma cell line were injected with yttrium-90 (90Y) conjugated to diethylene triaminepenta acetic acid (DTPA) alone, and DTPA covalently linked to a monoclonal antibody, B72.3. The animals were sacrificed in temporal sequence to evaluate isotope distribution. Dosimetry was carried out using the principles outlined in MIRD and ICRU Report 32. Results are expressed as percent uptake per unit mass in organs and tumor and as relative absorbed dose normalized to 90Y uptake in liver at 7 hr. When conjugated to B72.3, an 8-fold increase in isotope localization in the tumor was noted by 24 hr. When the relative absorbed dose is calculated for 90Y and 90Y.B72.3, a 26-fold increase in tumor dose is noted for the 90Y conjugate. Normal tissues show no to modest (less than 5x) enhanced dose with 90Y.B72.3. B72.3, therefore, deserves further investigation as a potential monoclonal antibody for targeting therapeutic radioisotopes and possibly diagnostic radioisotopes to pancreatic cancer. Radiobiological aspects of the low dose rates from radioimmunotherapy are discussed.

  20. Bremsstrahlung in {alpha} Decay Reexamined

    SciTech Connect

    Boie, H.; Scheit, H.; Jentschura, U. D.; Koeck, F.; Lauer, M.; Schwalm, D.; Milstein, A. I.; Terekhov, I. S.

    2007-07-13

    A high-statistics measurement of bremsstrahlung emitted in the {alpha} decay of {sup 210}Po has been performed, which allows us to follow the photon spectra up to energies of {approx}500 keV. The measured differential emission probability is in good agreement with our theoretical results obtained within the quasiclassical approximation as well as with the exact quantum mechanical calculation. It is shown that, due to the small effective electric dipole charge of the radiating system, a significant interference between the electric dipole and quadrupole contributions occurs, which is altering substantially the angular correlation between the {alpha} particle and the emitted photon.

  1. Preliminary evaluation of indigenous 90Y-labelled microspheres for therapy of hepatocellular carcinoma

    PubMed Central

    Subramanian, Suresh; Pandey, Usha; Chaudhari, Pradip; Tyagi, Monica; Gupta, Sanjay; Singh, Geetanjali; Dash, Ashutosh; Samuel, Grace; Venkatesh, Meera

    2016-01-01

    Background & objectives: Yttrium-90 (90Y)-based radioembolization has been employed to treat hepatocellular carcinoma (HCC) as commercial radioactive glass and polymeric resin microspheres. However, in India and other Asian countries, these preparations must be imported and are expensive, validating the need for development of indigenous alternatives. This work was aimed to develop an economically and logistically favourable indigenous alternative to imported radioembolizing agents for HCC therapy. Methods: The preparation of 90Y-labelled Biorex 70 microspheres was optimized and in vitro stability was assessed. Hepatic tumour model was generated in Sprague-Dawley rats by orthotopic implantation of N1S1 rat HCC cell line. In vivo localization and retention of the 90Y-labelled Biorex 70 microspheres was assessed for seven days, and impact on N1S1 tumour growth was studied by histological examination and biochemical assays. Results: Under optimal conditions, >95% 90Y-labelling yield of Biorex70 resin microspheres was obtained, and these showed excellent in vitro stability of labelling (>95%) at seven days. In animal studies, 90Y-labelled Biorex 70 microspheres were retained (87.72±1.56% retained in liver at 7 days). Rats administered with 90Y-labelled Biorex 70 microspheres exhibited lower tumour to liver weight ratio, reduced serum alpha-foetoprotein level and greater damage to tumour tissue as compared to controls. Interpretation & conclusions: 90Y-labelled Biorex 70 microspheres showed stable retention in the liver and therapeutic effect on tumour tissue, indicating the potential for further study towards clinical use. PMID:27748281

  2. Administered activity and outcomes of glass versus resin 90Y microsphere radioembolization in patients with colorectal liver metastases

    PubMed Central

    Nasr, Elie C.; Kunam, Vamsi K.; Bullen, Jennifer A.; Purysko, Andrei S.

    2016-01-01

    Background Given the differences in size, specific activity, and dosing methods for glass yttrium-90 microspheres (90Y-glass) and resin 90Y microspheres (90Y-resin), these therapies may expose the liver to different amounts of radiation, thereby affecting their efficacy and tolerability. We aimed to compare the prescribed activity of 90Y-glass and 90Y-resin for real-world patients undergoing selective internal radiation therapy (SIRT) for liver-dominant metastatic colorectal cancer (mCRC) and to assess efficacy and safety outcomes in these patients. Methods We examined the records of 28 consecutive patients with unresectable colorectal liver metastases treated with SIRT between June 2008 and May 2011 at our institution. Using baseline CT and MR images, we calculated a projected activity as if we had used the other product and compared it to the actual prescribed activity of 90Y-glass and 90Y-resin for each SIRT treatment per manufacturer guidelines. Progression and adverse events were evaluated at follow up visits. Survival was analyzed by the Kaplan-Meier method. Results For 90Y-glass treatments with a mean prescribed 90Y activity of 1.77 GBq, the mean projected 90Y-resin activity was 0.84 GBq. For 90Y-resin treatments with a mean prescribed 90Y activity of 1.05 GBq, the mean projected 90Y-glass activity was 2.48 GBq. The median survival was 9.3 months versus 18.2 months for 90Y-glass and 90Y-resin, respectively (P=0.292). During the second year after SIRT, the hazard ratio of death for patients treated with 90Y-glass versus 90Y-resin was 4.0 (95% CI: 1.3, 12.3; P=0.017). No significant difference in progression, adverse events or liver toxicity was observed. Conclusions Using manufacturer recommended guidelines, 90Y-resin delivers significantly less activity than 90Y-glass to patients with liver-dominant mCRC undergoing SIRT with no significant difference in adverse events and a trend toward improved survival. PMID:27563442

  3. Determination of 90Sr-90Y activity in urine samples by using Cherenkov counting.

    PubMed

    Tsroya, S; German, U; Pelled, O; Katorza, E; Alfassi, Z B

    2013-03-01

    Cherenkov counting of the (90)Sr-(90)Y pure beta emitters in aqueous samples is an attractive method; but color quenching correction is needed, this being especially significant for urine which is characterized by a strong coloration. A quench correction method based on the external source of some liquid scintillation systems (named ESAR-External Source Area Ratio) was proposed for aqueous solutions. In the present work, the application of the ESAR method for determination of (90)Sr-(90)Y in human urine samples is described.

  4. 90Y radioembolization versus chemoembolization in the treatment of hepatocellular carcinoma: an analysis of comparative effectiveness.

    PubMed

    Xing, Minzhi; Kokabi, Nima; Camacho, Juan C; Kooby, David A; El-Rayes, Bassel F; Kim, Hyun S

    2013-07-01

    Locoregional catheter-based therapies for unresectable hepatocellular carcinoma (HCC) include conventional transarterial chemoembolization (cTACE), drug-eluting bead chemoembolization and yttrium-90 ((90)Y) radioembolization. Although current guidelines recommend cTACE for inoperable HCC, comparative effectiveness of drug-eluting bead chemoembolization and (90)Y radioembolization in the management of HCC remains undefined due to the lack of data evaluating safety and effectiveness among these therapies. A comprehensive search of the literature was carried out for studies examining comparative effectiveness of cTACE and (90)Y based on objective tumor response and overall patient survival. Further data on efficacy, safety, toxicity and cost-effectiveness was also examined. The National Cancer Institute Levels of Evidence for Cancer Treatment Studies provided a useful framework for the critical understanding and stratification of current evidence on locoregional therapy for unresectable HCC. Based on current retrospective cohort studies, evidence for similar efficacy and safety between cTACE and (90)Y radioembolization was demonstrated. Further prospective, randomized studies are required to validate these observations and to analyze cost-effectiveness of these interventions in unresectable HCC patients for definitive recommendations to be made.

  5. Neuroreceptor imaging with SPECT.

    PubMed

    Innis, R B

    1992-11-01

    Single photon emission computed tomography (SPECT) imaging can provide useful measurements of brain receptors and endogenous neurotransmitters and may have significant experimental and clinical applications. This presentation reviews the use of SPECT for neuroreceptor imaging. Studies of receptors for benzodiazepines, dopamine D2 agents, and dopamine reuptake sites will be used to exemplify the capabilities of SPECT. Tracers labeled with the radioisotope 125I have high affinity, high brain uptake, and high ratios of specific to nonspecific binding. Imaging studies of human and nonhuman primate brain will be presented, and the potential clinical applicability of these agents will be discussed.

  6. Radiopharmaceutical development based on human blood albumin microspheres and 90Y

    NASA Astrophysics Data System (ADS)

    Petriev, V. M.; Vlasova, O. P.; Postnov, A. A.; Epstein, N. B.

    2017-01-01

    New radiopharmaceutial (RP) based on human serum albumin microspheres (MSA) and 90Y was developed for treatment of liver cancer. The optimized synthesis using chelation resulted in approximately 80% yield with high specific activity. The RP developed was tested in mice with inoculated sarcoma-37. In two weeks the tumor size reduced by 43% after the treatment with the dose of 500 μCi injected into the tumor site.

  7. Internal bremsstrahlung of strongly interacting charged particles

    NASA Astrophysics Data System (ADS)

    Kurgalin, S. D.; Tchuvil'sky, Yu. M.; Churakova, T. A.

    2016-11-01

    A universal theoretical model intended for calculating internal-bremsstrahlung spectra is proposed. In this model, which can be applied to describing nuclear decays of various type (such as alpha decay, cluster decay, and proton emission), use is made of realistic nucleus-nucleus potentials. Theoretical internal-bremsstrahlung spectra were obtained for the alpha decay of the 214Po nucleus, as well as for the decay of the 222Ra nucleus via the emission of a 14C cluster and for the decay of the 113Cs nucleus via proton emission, and the properties of these spectra were studied. The contributions of various regions (internal, subbarrier, and external) to the internal-bremsstrahlung amplitude were analyzed in detail. It is shown that the contribution of the internal region to the amplitude for internal bremsstrahlung generated in nuclear decay via proton emission is quite large, but that this is not so for alpha decay and decay via cluster emission. Thus, a process in which strong interaction of nuclear particles affects the internal-bremsstrahlung spectrum if found.

  8. SU-E-T-02: 90Y Microspheres Dosimetry Calculation with Voxel-S-Value Method: A Simple Use in the Clinic

    SciTech Connect

    Maneru, F; Gracia, M; Gallardo, N; Olasolo, J; Fuentemilla, N; Bragado, L; Martin-Albina, M; Lozares, S; Pellejero, S; Miquelez, S; Rubio, A; Otal, A

    2015-06-15

    Purpose: To present a simple and feasible method of voxel-S-value (VSV) dosimetry calculation for daily clinical use in radioembolization (RE) with {sup 90}Y microspheres. Dose distributions are obtained and visualized over CT images. Methods: Spatial dose distributions and dose in liver and tumor are calculated for RE patients treated with Sirtex Medical miscrospheres at our center. Data obtained from the previous simulation of treatment were the basis for calculations: Tc-99m maggregated albumin SPECT-CT study in a gammacamera (Infinia, General Electric Healthcare.). Attenuation correction and ordered-subsets expectation maximization (OSEM) algorithm were applied.For VSV calculations, both SPECT and CT were exported from the gammacamera workstation and registered with the radiotherapy treatment planning system (Eclipse, Varian Medical systems). Convolution of activity matrix and local dose deposition kernel (S values) was implemented with an in-house developed software based on Python code. The kernel was downloaded from www.medphys.it. Final dose distribution was evaluated with the free software Dicompyler. Results: Liver mean dose is consistent with Partition method calculations (accepted as a good standard). Tumor dose has not been evaluated due to the high dependence on its contouring. Small lesion size, hot spots in health tissue and blurred limits can affect a lot the dose distribution in tumors. Extra work includes: export and import of images and other dicom files, create and calculate a dummy plan of external radiotherapy, convolution calculation and evaluation of the dose distribution with dicompyler. Total time spent is less than 2 hours. Conclusion: VSV calculations do not require any extra appointment or any uncomfortable process for patient. The total process is short enough to carry it out the same day of simulation and to contribute to prescription decisions prior to treatment. Three-dimensional dose knowledge provides much more information than

  9. Abdominal SPECT imaging

    SciTech Connect

    Van Heertum, R.L.; Brunetti, J.C.; Yudd, A.P.

    1987-07-01

    Over the past several years, abdominal single photon emission computed tomography (SPECT) imaging has evolved from a research tool to an important clinical imaging modality that is helpful in the diagnostic assessment of a wide variety of disorders involving the abdominal viscera. Although liver-spleen imaging is the most popular of the abdominal SPECT procedures, blood pool imaging is becoming much more widely utilized for the evaluation of cavernous hemangiomas of the liver as well as other vascular abnormalities in the abdomen. Adjunctive indium leukocyte and gallium SPECT studies are also proving to be of value in the assessment of a variety of infectious and neoplastic diseases. As more experience is acquired in this area, SPECT should become the primary imaging modality for both gallium and indium white blood cells in many institutions. Renal SPECT, on the other hand, has only recently been used as a clinical imaging modality for the assessment of such parameters as renal depth and volume. The exact role of renal SPECT as a clinical tool is, therefore, yet to be determined. 79 references.

  10. Bremsstrahlung from relativistic heavy ions in matter

    SciTech Connect

    Soerensen, Allan H.

    2010-02-15

    The emission of electromagnetic radiation by relativistic bare heavy ions penetrating ordinary matter is investigated. Our main aim is to determine the bremsstrahlung which we define as the radiation emitted when the projectile does not break up. It pertains to collisions without nuclear contact ('ultraperipheral collisions'). Requirement of coherent action of the nucleons in order to keep the penetrating projectile intact limits bremsstrahlung to relatively soft photons. The spectrum shows a resonance structure with peak position near 2{gamma} times the position of the giant dipole resonance, that is, near 25{gamma} MeV for a lead ion ({gamma}{identical_to}E/Mc{sup 2} is the Lorentz factor of the projectile of energy E and mass M). The maximum exceeds the bremsstrahlung from a hypothetical structureless, pointlike particle of the same charge and mass as the incoming nucleus, but rapid depletion follows on the high-energy side of the peak. As a result of its relative softness, bremsstrahlung never dominates the energy-loss process for heavy ions. As to the emission of electromagnetic radiation in collisions with nuclear break-up, it appears modest when pertaining to incoherent action of the projectile nucleons in noncontact collisions. In collisions with nuclear contact, though, substantial radiation is emitted. It overshoots the bremsstrahlung. However, despite the violence of contact events, the associated photon emission only exceeds the radiation from a hypothetical structureless pointlike nucleus [emitted energy per unit photon-energy interval essentially constant up to ({gamma}-1)Mc{sup 2}] at relatively low photon energies (for lead roughly below 0.2{gamma} GeV, a limit which is about an order of magnitude above the position of the bremsstrahlung peak). Results are presented for bare lead ions penetrating a solid lead target at energies of 158 GeV/n ({gamma}=170) and beyond.

  11. Reducing renal uptake of 90Y- and 177Lu-labeled alpha-melanocyte stimulating hormone peptide analogues

    SciTech Connect

    Miao, Yubin; Fisher, Darrell R.; Quinn, Thomas P.

    2006-06-15

    The purpose of this study was to improve the tumor-to-kidney uptake ratios of 90Y- and 177Lu-[1,2,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid-Re-Cys,D-Phe,Arg]alpha-melanocyte stimulating hormone (DOTA-RE(Arg)CCMSH), through coupling a negatively charged glutamic acid (Glu) to the peptide sequence. A new peptide of DOTA-Re(Glu,Arg)CCMSH was designed, synthesized and labeled with 90Y and 177Lu. Pharmacokinetics of 90Y- and 177Lu-DOTA-RE(Glu,Arg)CCNSH were determined in B16/F1 murine melanoma-bearing C57 mice. Both exhibited significantly less renal uptake than 90Y- and 177Lu-DOTA-Re(Arg)CCMSH at 30 min and at 2, 3, and 24 h after dose administration. The renal uptake values of 90Y- and 177Lu-DOTA-Re(Glu,Arg)CCMSH were 28.16% and 28.81% of those of 90Y- and 177Lu-DOTA-RE(Arg)CCMSH, respectively, at 4 hr post-injection. We also showed higher tumor-to-kidney uptake ratios 2.28 and 1.69 times that of 90Y- and 177Lu-DOTA-Re(Arg)CCMSH, respectively, at 4 h post-injection. The90Y- and 177Lu-DOTA-Re(Glu,Arg)CCMSH activity accumulation was low in normal organs except for kidneys. Coupling a negatively charged amino acid (Glu) to the CCMSH peptide sequence dramatically reduced the renal uptake values and increased the tumor-to-kidney uptake ratios of 90Y- and 177Lu-DOTA-Re(Glu,Arg)CCMSH, facilitating their potential applications as radiopharmaceuticals for targeted radionuclide therapy of melanoma.

  12. Standardisation of (90)Y and determination of calibration factors for (90)Y microspheres (resin) for the NPL secondary ionisation chamber and a Capintec CRC-25R.

    PubMed

    Ferreira, Kelley M; Fenwick, Andrew J; Arinc, Arzu; Johansson, Lena C

    2016-03-01

    The use of (90)Y resin microspheres (SIR-Spheres® microspheres) in Nuclear Medicine has dramatically increased in recent years due to its favourable outcome in the treatment of liver cancer and liver metastases (Rajekar et al., 2011). The measurement of administered activity before and residual activity after treatment in radionuclide calibrators is required to determine total activity delivered to the patient. In comparison with External Beam Radiotherapy (EBRT) where administered doses are often know to within ±5%, the actual administered activity in nuclear medicine procedures may only be known to within ±20% and subsequent dose calculations can result in even larger uncertainties (Fenwick et al., 2009). It is a well-recognised issue that ion chambers are instruments that are sensitive to the measurement geometry and matrix of a source, in particular for pure beta or low energy (<100keV) x-ray emitters (Gadd et al., 2006). This paper presents new calibration factors for NPL secondary standard ionisation chamber system (Vinten 671) and a Capintec CRC-25R radionuclide calibrator along with a discussion of the measurement problems associated with this radionuclide and matrix. Calibration of the NPL secondary standard system for this measurement matrix will enable NPL to provide standards for the Nuclear Medicine community and consequently increase the measurement capability.

  13. Quantitative myocardial perfusion SPECT.

    PubMed

    Tsui, B M; Frey, E C; LaCroix, K J; Lalush, D S; McCartney, W H; King, M A; Gullberg, G T

    1998-01-01

    In recent years, there has been much interest in the clinical application of attenuation compensation to myocardial perfusion single photon emission computed tomography (SPECT) with the promise that accurate quantitative images can be obtained to improve clinical diagnoses. The different attenuation compensation methods that are available create confusion and some misconceptions. Also, attenuation-compensated images reveal other image-degrading effects including collimator-detector blurring and scatter that are not apparent in uncompensated images. This article presents basic concepts of the major factors that degrade the quality and quantitative accuracy of myocardial perfusion SPECT images, and includes a discussion of the various image reconstruction and compensation methods and misconceptions and pitfalls in implementation. The differences between the various compensation methods and their performance are demonstrated. Particular emphasis is directed to an approach that promises to provide quantitative myocardial perfusion SPECT images by accurately compensating for the 3-dimensional (3-D) attenuation, collimator-detector response, and scatter effects. With advances in the computer hardware and optimized implementation techniques, quantitatively accurate and high-quality myocardial perfusion SPECT images can be obtained in clinically acceptable processing time. Examples from simulation, phantom, and patient studies are used to demonstrate the various aspects of the investigation. We conclude that quantitative myocardial perfusion SPECT, which holds great promise to improve clinical diagnosis, is an achievable goal in the near future.

  14. A Sr-90/Y-90 field calibrator for performance testing of beta-gamma survey instruments

    SciTech Connect

    Olsher, R.H.; Haynie, J.S.

    1988-01-01

    ANSI and regulatory agency guidelines prescribe periodic performance tests for radiation protection instrumentation. Reference readings should be obtained for one point on each scale or decade normally used. A small and lightweight calibrator has been developed that facilitates field testing of beta-gamma survey instruments. The calibrator uses a 45 microcurie Sr-90/Y-90 beta source with a filter wheel to generate variable dose rates in the range from 4 to 400 mrad/hr. Thus, several ranges may be checked by dialing in appropriate filters. The design, use, and typical applications of the calibrator are described.

  15. Gastrectomy for the treatment of refractory gastric ulceration after radioembolization with 90Y microspheres

    PubMed Central

    Yim, Sun Young; Jung, Jin Yong; Kim, Chang Ha; Seo, Yeon Seok; Yim, Hyung Joon; Um, Soon Ho; Ryu, Ho Sang; Kim, Yun Hwan; Kim, Chong Suk; Shin, Eun

    2014-01-01

    Transcatheter arterial radioembolization (TARE) with Yttrium-90 (90Y)-labeled microspheres has an emerging role in treatment of patients with unresectable hepatocellular carcinoma. Although complication of TARE can be minimized by aggressive pre-evaluation angiography and preventive coiling of aberrant vessels, radioembolization-induced gastroduodenal ulcer can be irreversible and can be life-threatening. Treatment of radioembolization-induced gastric ulcer is challenging because there is a few reported cases and no consensus for management. We report a case of severe gastric ulceration with bleeding that eventually required surgery due to aberrant deposition of microspheres after TARE. PMID:25320734

  16. Treatment of cystic craniopharyngioma with 90Y-Colloid. Four clinical cases.

    PubMed

    Sabaté-Llobera, A; Rojas-Camacho, J G; Mora Salvadó, J; Acebes Martín, J J; Rodríguez-Gasén, A; Ramal Leiva, D; Martín-Comín, J

    2013-01-01

    Craniopharyngioma is a histologically benign and frequently cystic intracranial tumor. It may present aggressive behavior due to compression from nearby structures. Its therapeutic management is complicated because although surgery is the usual treatment of choice, it is not exempt of high morbidity and mortality and frequent tumor recurrence. In craniopharyngiomas with a significant cystic component,internal irradiation with radioactive isotopes is a therapeutic alternative to conventional treatments. We present the cases of four patients with cystic craniopharyngiomas who were treated with intracystic administration of 90Y-colloid, and their evolution after the treatment.

  17. Bremsstrahlung gamma rays from light dark matter

    SciTech Connect

    Cirelli, Marco; Zaharijas, Gabrijela E-mail: serpico@lapth.cnrs.fr

    2013-11-01

    We discuss the often-neglected role of bremsstrahlung processes on the interstellar gas in computing indirect signatures of Dark Matter (DM) annihilation in the Galaxy, particularly for light DM candidates in the phenomenologically interesting O(10) GeV mass range. Especially from directions close to the Galactic Plane, the γ-ray spectrum is altered via two effects: directly, by the photons emitted in the bremsstrahlung process by energetic electrons which are among the DM annihilation byproducts; indirectly, by the modification of the same electron spectrum, due to the additional energy loss process in the diffusion-loss equation (e.g. the resulting inverse Compton emission is altered). We quantify the importance of the bremsstrahlung emission in the GeV energy range, showing that it is sometimes the dominant component of the γ-ray spectrum. We also find that, in regions in which bremsstrahlung dominates energy losses, the related γ-ray emission is only moderately sensitive to possible large variations in the gas density. Still, we stress that, for computing precise spectra in the (sub-)GeV range, it is important to obtain a reliable description of the Galaxy gas distribution as well as to compute self-consistently the γ-ray emission and the solution to the diffusion-loss equation. For example, these are crucial issues to quantify and interpret meaningfully γ-ray map 'residuals' in the inner Galaxy.

  18. History and status of coherent bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Überall, Herbert

    2005-08-01

    Coherent bremsstrahlung research originated with the 1955 papers by Dyson and Uberall, Ter-Mikaelian, and Ferretti. Its intermediate status thirty years later has been documented by Saenz and Uberall in the book Coherent Radiation Sources (A. W. Sáenz and H. Überall, editors), Springer, Berlin 1985. The first precision experiments were carried out by Diambrini-Palazzi et al. (1 960) in Frascati shortly after the theory had been developed; see also Timm (1 969). After experimentation by dozens of electron accelerator laboratories all over the world, there are presently measurements being made by Arends et al. at the University of Mainz (MAMI, 855 MeV), Klein et al. at the University of Bonn (ELSA, 3 GeV), at CERN (20-170 GeV) by Avakian of the Yerevan Physics Institute and others, and with electron energies of 6 GeV at the Jefferson Laboratory, Newport News, VA (F. J. Klein, Catholic University, spokesperson). At Jefferson Lab, linearly polarized quasi-monochromatic coherent-bremsstrahlung photons [peaked at 1.8GeV, with polarization (after collimation) of 84%] are being used for the production (off protons) of ρ and ω mesons among others. Recent theoretical research deals with coherent bremsstrahlung in quasicrystals (Fusina, Langworthy, and Saenz, 2001), and with planar and axial coherent bremsstrahlung in a diamond crystal (Chouffani, Endo, and Uberall 2001-2), both at low energies. In the latter study, in which the concept of axial coherent bremsstrahlung is now stressed (while in the related processes of planar and axial channeling radiation this distinction is well known), photon emission occurs here not necessarily in the forward direction.

  19. Time optimization of (90)Sr measurements: Sequential measurement of multiple samples during ingrowth of (90)Y.

    PubMed

    Holmgren, Stina; Tovedal, Annika; Björnham, Oscar; Ramebäck, Henrik

    2016-04-01

    The aim of this paper is to contribute to a more rapid determination of a series of samples containing (90)Sr by making the Cherenkov measurement of the daughter nuclide (90)Y more time efficient. There are many instances when an optimization of the measurement method might be favorable, such as; situations requiring rapid results in order to make urgent decisions or, on the other hand, to maximize the throughput of samples in a limited available time span. In order to minimize the total analysis time, a mathematical model was developed which calculates the time of ingrowth as well as individual measurement times for n samples in a series. This work is focused on the measurement of (90)Y during ingrowth, after an initial chemical separation of strontium, in which it is assumed that no other radioactive strontium isotopes are present. By using a fixed minimum detectable activity (MDA) and iterating the measurement time for each consecutive sample the total analysis time will be less, compared to using the same measurement time for all samples. It was found that by optimization, the total analysis time for 10 samples can be decreased greatly, from 21h to 6.5h, when assuming a MDA of 1Bq/L and at a background count rate of approximately 0.8cpm.

  20. Dynamic Metabolic Changes during the First 3 Months after 90Y-Ibritumomab Tiuxetan Radioimmunotherapy

    PubMed Central

    Koyama, Keitaro; Kurokawa, Mineo; Ohtomo, Kuni

    2014-01-01

    Objective. To elucidate the time course of tumor metabolism during the first 3 months after 90Y-ibritumomab tiuxetan radioimmunotherapy (RIT) in patients with refractory malignant lymphoma. Materials and Methods. Seven patients with recurrent follicular lymphoma underwent FDG-PET imaging before and after 1-, 4-, and 12-week RIT with 90Y-ibritumomab tiuxetan. Tumor metabolic activity on FDG-PET scans was assessed as the maximum standard uptake value (SUVmax). Results. Decrease in metabolism was detected 1 week after RIT. In the most decreased lesion, SUVmax decreased to 20% of the baseline value during the first week. Most lesions continued to decrease for up to 4 weeks. Some lesions showed increased metabolism from 4 to 12 weeks, while the level of FDG accumulations at 12 weeks was still lower than the baseline. Conclusions. Tumor response to RIT could be observed as early as 1 week after the administration of RIT. After tumor activity decreases, the metabolism may increase at least between 4 and 12 weeks. It suggests that the metabolic changes should be carefully evaluated during this period. PMID:25050390

  1. Bremsstrahlung: an experimentalist's personal perspective on the postmodern era

    NASA Astrophysics Data System (ADS)

    Quarles, C. A.

    2000-08-01

    In this brief review I will discuss the recent experimental work on the doubly differential cross section, i.e. the photon energy and angular distribution, for electron bremsstrahlung from thin solid film and gas targets. Since the beginning of the modern era in the study of bremsstrahlung with the publication of the 1971 paper by Tseng and Pratt, Professor Pratt has been the dominant influence in bremsstrahlung research. Most, if not all, experimental research during the modern era has been motivated by the interest in comparing data with the theory of Pratt and his coworkers. As bremsstrahlung research has moved into its postmodern era, new experiments with increasing precision are concentrating on determining under what conditions ordinary bremsstrahlung theory needs to be supplemented by a contribution from polarization bremsstrahlung. Efforts to improve the comparison of thin-target experiment with theory have also led to new experimental and modeling work on bremsstrahlung from thick solid targets. Thick-target bremsstrahlung is interesting in its own right, but we also want to understand it better since it is the ever-present background in the thin-target experiments and the limiting factor in the effort to distinguish the polarization contribution to the total bremsstrahlung spectrum. Professor Pratt ushered in the modern era in bremsstrahlung research and has recently guided the transition into the postmodern era. It can be expected that he will continue to have a formative influence on the developments of bremsstrahlung research into the foreseeable future.

  2. Gluon Bremsstrahlung in Weakly-Coupled Plasmas

    NASA Astrophysics Data System (ADS)

    Arnold, Peter

    2009-11-01

    I report on some theoretical progress concerning the calculation of gluon bremsstrahlung for very high energy particles crossing a weakly-coupled quark-gluon plasma. (i) I advertise that two of the several formalisms used to study this problem, the BDMPS-Zakharov formalism and the AMY formalism (the latter used only for infinite, uniform media), can be made equivalent when appropriately formulated. (ii) A standard technique to simplify calculations is to expand in inverse powers of logarithms ln(E/T). I give an example where such expansions are found to work well for ω/T≳10 where ω is the bremsstrahlung gluon energy. (iii) Finally, I report on perturbative calculations of q̂.

  3. Synthesis and Comparative Biological Evalution of Bifunctional Ligands for Radiotherapy Applications of 90Y and 177Lu

    PubMed Central

    Chong, Hyun-Soon; Sun, Xiang; Chen, Yunwei; Sin, Inseok; Kang, Chi Soo; Lewis, Michael R.; Liu, Dijie; Ruthengael, Varyanna C.; Zhong, Yongliang; Wu, Ningjie; Song, Hyun A

    2015-01-01

    Zevalin® is an antibody-drug conjugate radiolabeled with a cytotoxic radioisotope (90Y) that was approved for radioimmunotherapy (RIT) of B-cell non-Hodgkin’s lymphoma. A bifunctional ligand that displays favorable complexation kinetics and in vivo stability is required for effective RIT. New bifunctional ligands 3p-C-DE4TA and 3p-C-NE3TA for potential use in RIT were efficiently prepared by the synthetic route based on regiospecific ring opening of aziridinium ions with prealkylated triaza- or tetraaza-backboned macrocycles. The new bifunctional ligands 3p-C-DE4TA and 3p-C-NE3TA along with the known bimodal ligands 3p-C-NETA and 3p-C-DEPA were comparatively evaluated for potential use in targeted radiotherapy using β-emitting radionuclides 90Y and 177Lu. The bifunctional ligands were evaluated for radiolabeling kinetics with 90Y and 177Lu, and the corresponding 90Y or 177Lu-radiolabeled complexes were studied for in vitro stability in human serum and in vivo biodistribution in mice. The results of the comparative complexation kinetic and stability studies indicate that size of macrocyclic cavity, ligand denticity, and bimodality of donor groups have a substantial impact on complexation of the bifunctional ligands with the radiolanthanides. The new promising bifunctional chelates in the DE4TA and NE3TA series were rapid in binding 90Y and 177Lu, and the corresponding 90Y- and 177Lu-radiolabeled complexes remained inert in human serum or in mice. The in vitro and in vivo data show that 3p-C-DE4TA and 3p-C-NE3TA are promising bifunctional ligands for targeted radiotherapy applications of 90Y and 177Lu. PMID:25648683

  4. Intra-arterial {sup 90}Y brachytherapy: Preliminary dosimetric study using a specially modified angioplasty balloon

    SciTech Connect

    Popowski, Y.; Nouet, P.; Rouzaud, M.

    1995-10-15

    Irradiation has been shown to be effective in preventing restenosis after dilatation in human peripheral arteries. We have developed a dedicated system for coronary intraarterial irradiation using a {sup 90}Y pure beta-emitting source inside a specially modified angioplasty balloon. This paper presents a preliminary dosimetric evaluation of this system. Thermoluminescent dosimetric measurements using the standard balloons filled with contrast medium were plotted semilogarithmically as a function of distance from the balloon surface. The logarithms of the measured doses fit a straight line as a function of depth. The doses at 1 mm and 3 mm are approximately 50 and 10% of the surface dose, respectively. Due to the poor centering of the source in the conventional balloons, the dispersion and standard deviations (SDs) of the measured surface doses increased proportionally to the balloon diameter (SDs are 1.89, 5.52, 5.79, and 6.46 Gy for 2.5, 3, 3.5, and 4 mm balloon diameters, respectively). For the 3.5 mm centering and conventional balloons the respective mean, minimum, and maximum surface doses were 8.41 Gy (min.7.26; max. 9.46) and 7.89 Gy (min. 2.18; max. 16.06) and their standard deviations were 0.66 and 5.79 Gy, respectively. Conventional angioplasty balloons cannot ensure a homogeneous dose delivery to an arterial wall with an intralumenal {sup 90}Y beta source. Preliminary dosimetric results using a modified centering balloon show that it permits improved surface dose distribution (axial and circumferential homogeneity), making it suitable for clinical applications. 9 refs., 5 figs.

  5. Comparative Efficacy of 177Lu and 90Y for Anti-CD20 Pretargeted Radioimmunotherapy in Murine Lymphoma Xenograft Models

    PubMed Central

    Frost, Sofia H. L.; Frayo, Shani L.; Miller, Brian W.; Orozco, Johnnie J.; Booth, Garrett C.; Hylarides, Mark D.; Lin, Yukang; Green, Damian J.; Gopal, Ajay K.; Pagel, John M.; Bäck, Tom A.; Fisher, Darrell R.; Press, Oliver W.

    2015-01-01

    Purpose Pretargeted radioimmunotherapy (PRIT) is a multi-step method of selectively delivering high doses of radiotherapy to tumor cells while minimizing exposure to surrounding tissues. Yttrium-90 (90Y) and lutetium-177 (177Lu) are two of the most promising beta-particle emitting radionuclides used for radioimmunotherapy, which despite having similar chemistries differ distinctly in terms of radiophysical features. These differences may have important consequences for the absorbed dose to tumors and normal organs. Whereas 90Y has been successfully applied in a number of preclinical and clinical radioimmunotherapy settings, there have been few published pretargeting studies with 177Lu. We therefore compared the therapeutic potential of targeting either 90Y or 177Lu to human B-cell lymphoma xenografts in mice. Methods Parallel experiments evaluating the biodistribution, imaging, dosimetry, therapeutic efficacy, and toxicity were performed in female athymic nude mice bearing either Ramos (Burkitt lymphoma) or Granta (mantle cell lymphoma) xenografts, utilizing an anti-CD20 antibody-streptavidin conjugate (1F5-SA) and an 90Y- or 177Lu-labeled 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-biotin second step reagent. Results The two radionuclides displayed comparable biodistributions in tumors and normal organs; however, the absorbed radiation dose delivered to tumor was more than twice as high for 90Y (1.3 Gy/MBq) as for 177Lu (0.6 Gy/MBq). More importantly, therapy with 90Y-DOTA-biotin was dramatically more effective than with 177Lu-DOTA-biotin, with 100% of Ramos xenograft-bearing mice cured with 37 MBq 90Y, whereas 0% were cured using identical amounts of 177Lu-DOTA-biotin. Similar results were observed in mice bearing Granta xenografts, with 80% of the mice cured with 90Y-PRIT and 0% cured with 177Lu-PRIT. Toxicities were comparable with both isotopes. Conclusion 90Y was therapeutically superior to 177Lu for streptavidin-biotin PRIT approaches in

  6. External Beam Radiotherapy Followed by {sup 90}Y Ibritumomab Tiuxetan in Relapsed or Refractory Bulky Follicular Lymphoma

    SciTech Connect

    Burdick, Michael J.; Neumann, Donald; Pohlman, Brad; Reddy, Chandana A.; Tendulkar, Rahul D.; Macklis, Roger

    2011-03-15

    Purpose: We combined external beam radiotherapy (EBRT) with yttrium-90 ibritumomab tiuxetan ({sup 90}Y-IT) in an attempt to improve therapeutic response in patients with relapsed or refractory bulky follicular lymphoma (RRBFL). Methods and Materials: Between February 2006 and September 2007, 11 patients with RRBFL were treated with EBRT followed by {sup 90}Y-IT. Bulky disease (BD) was defined as >5 cm. EBRT was delivered to BD as 2,400 cGy in eight fractions using computed tomography (CT)-based planning. BD was contoured as the gross tumor volume. A planning margin of 1 to 2 cm was added depending on anatomical location. After recovery of complete blood counts (CBC), {sup 90}Y-IT was administered at a dose of 0.3 or 0.4 mCi/kg depending on platelet counts. Hematologic toxicity was monitored through weekly CBC. Response was measured by positron emission tomography/CT or CT 3-4 months after {sup 90}Y-IT. Results: Only 2 patients required prolonged breaks between EBRT and {sup 90}Y-IT. The median time after {sup 90}Y-IT for platelets to recover to >100,000/ml was 55 days (range, 41-128 days). Platelet counts for 1 patient, who had received 4 previous chemotherapy regimens, never reached 100,000/ml. The complete and overall responses to combined therapy as measured 3-4 months after {sup 90}Y-IT were 64%. No patients relapsed within the EBRT field. With a median follow-up of 36.1 months, 6 patients have relapsed, 2 of whom have died. Median progression-free survival was 17.5 months. Conclusions: In contrast to prior failure analysis data for RRBFL patients treated with {sup 90}Y-IT alone, a brief course of EBRT prevented relapse in sites of BD. EBRT used to pretreat bulky sites may improve clinical outcomes and potentially extend survival when combined with {sup 90}Y-IT.

  7. Comparative efficacy of 177Lu and 90Y for Anti-CD20 Pretargeted Radioimmunotherapy in Murine Lymphoma Xenograft Models

    DOE PAGES

    Frost, Sofia H. L.; Frayo, Shani L.; Miller, Brian W.; ...

    2015-03-18

    Purpose Pretargeted radioimmunotherapy (PRIT) is a multi-step method of selectively delivering high doses of radiotherapy to tumor cells while minimizing exposure to surrounding tissues. Yttrium-90 (90Y) and lutetium-177 (177Lu) are two of the most promising beta-particle emitting radionuclides used for radioimmunotherapy, which despite having similar chemistries differ distinctly in terms of radiophysical features. These differences may have important consequences for the absorbed dose to tumors and normal organs. Whereas 90Y has been successfully applied in a number of preclinical and clinical radioimmunotherapy settings, there have been few published pretargeting studies with 177Lu. We therefore compared the therapeutic potential of targetingmore » either 90Y or 177Lu to human B-cell lymphoma xenografts in mice. Methods Parallel experiments evaluating the biodistribution, imaging, dosimetry, therapeutic efficacy, and toxicity were performed in female athymic nude mice bearing either Ramos (Burkitt lymphoma) or Granta (mantle cell lymphoma) xenografts, utilizing an anti-CD20 antibodystreptavidin conjugate (1F5-SA) and an 90Y- or 177Lu-labeled 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-biotin second step reagent. Results The two radionuclides displayed comparable biodistributions in tumors and normal organs; however, the absorbed radiation dose delivered to tumor was more than twice as high for 90Y (1.3 Gy/MBq) as for 177Lu (0.6 Gy/MBq). More importantly, therapy with 90Y-DOTAbiotin was dramatically more effective than with 177Lu-DOTA-biotin, with 100% of Ramos xenograft-bearing mice cured with 37 MBq 90Y, whereas 0% were cured using identical amounts of 177Lu-DOTA-biotin. Similar results were observed in mice bearing Granta xenografts, with 80% of the mice cured with 90Y-PRIT and 0% cured with 177Lu-PRIT. Toxicities were comparable with both isotopes. Conclusion 90Y was therapeutically superior to 177Lu for streptavidin-biotin PRIT

  8. Comparative Efficacy of 177Lu and 90Y for Anti-CD20 Pretargeted Radioimmunotherapy in Murine Lymphoma Xenograft Models

    SciTech Connect

    Frost, Sophia; Frayo, Shani; Miller, Brian W.; Orozco, Johnnie J.; Booth, Garrett C.; Hylarides, Mark; Lin, Yukang; Green, Damian J.; Gopal, Ajay K.; Pagel, John M.; Back, Tom; Fisher, Darrell R.; Press, Oliver W.

    2015-03-01

    Pretargeted radioimmunotherapy (PRIT) is a multi-step method of selectively delivering high doses of radiotherapy to tumor cells while minimizing exposure to surrounding tissues. Yttrium-90 (90Y) and lutetium-177 (177Lu) are two of the most promising beta-particle emitting radionuclides used for radioimmunotherapy, which despite having similar chemistries differ distinctly in terms of radiophysical features. These differences may have important consequences for the absorbed dose to tumors and normal organs. Whereas 90Y has been successfully applied in a number of preclinical and clinical radioimmunotherapy settings, there have been few published pretargeting studies with 177Lu. We therefore compared the therapeutic potential of targeting either 90Y or 177Lu to human B-cell lymphoma xenografts in mice.

  9. Radioimmunotherapy ((90) Y-Ibritumomab Tiuxetan) for Posttransplant Lymphoproliferative Disorders After Prior Exposure to Rituximab.

    PubMed

    Rossignol, J; Terriou, L; Robu, D; Willekens, C; Hivert, B; Pascal, L; Guieze, R; Trappe, R; Baillet, C; Huglo, D; Morschhauser, F

    2015-07-01

    Posttransplantation lymphoproliferative disorders (PTLDs) are life-threatening complications after solid organ and hematopoietic stem cell transplantation. Only half of CD20-positive PTLDs respond to rituximab monotherapy, and outcomes remain poor for patients with relapsed/refractory disease, especially those who do not qualify for an anthracycline containing regimen due to frailty or comorbidities. Radioimmunotherapy (RIT) might be an option in this particular setting. We report a panel of eight patients with rituximab refractory/relapsed CD20-positive PTLDs including three ineligible for subsequent CHOP-like chemotherapy who received (90) Y-Ibritumomab tiuxetan as a single agent (n = 7) or combined to chemotherapy (n = 1). Five out of eight patients were kidney transplant recipients, while 2/8 had a liver transplant and 1/8 had a heart transplant. Patients received a median of two previous therapies. Overall response rate was 62.5%. Importantly, all responders achieved complete response. At a median follow-up of 37 months [5; 84], complete response was ongoing in four patients. Toxicity was predominantly hematological and easily manageable. No graft rejection was noticed concomitantly or following RIT administration despite immunosuppression reduction after diagnosis of PTLDs. This report emphasizes the potential efficiency of salvage RIT for early rituximab refractory PTLDs without any unexpected toxicity.

  10. Verification and uniformity control of doses for 90Sr/90Y intravascular brachytherapy sources using radiochromic film dosimetry

    PubMed Central

    Demir, Bayram; Ahmed, Asm Sabbir; Babalik, Erhan; Demir, Mustafa; Gürmen, Tevfik

    2008-01-01

    Intravascular brachytherapy (IVBT) is a useful treatment modality for the recurrence of in-stent restenosis following drug-eluting stents (DES) or IVBT failure. The objective of this study was to measure the dose rate of 90Sr/90Y IVBT sources for comparison with that given by the manufacturer and to control the dose uniformities of these sources along the source axis. The dose rates of 90Sr/90Y beta sources were measured with a radiochromic film in a custom-made phantom. The films for calibration were irradiated using 60Co photon beams. The results for the three sources were 4.5%, 2.3%, and 3.5% higher than the corresponding certificate values. Maximum and minimum of the dose rates varied within ±10% of those at source center; and maximum dose discrepancy for the first 90Sr/90Y source train was 8.2%; for the second source train, 7.1%; and for the third source train, 5.1%. Our study showed that the dose rates given by the manufacturer for the three 90Sr/90Y IVBT sources were reliable and dose uniformities were within ±10% along two thirds of the treatment length. PMID:19893691

  11. (90)Y microspheres prepared by sol-gel method, promising medical material for radioembolization of liver malignancies.

    PubMed

    Łada, Wiesława; Iller, Edward; Wawszczak, Danuta; Konior, Marcin; Dziel, Tomasz

    2016-10-01

    A new technology for the production of radiopharmaceutical (90)Y microspheres in the form of spherical yttrium oxide grains obtained by sol-gel method has been described. The authors present and discuss the results of investigations performed in the development of new production technology of yttrium microspheres and determination of their physic-chemical properties. The final product has the structure of spherical yttrium oxide grains with a diameter 25-100μm, is stable and free from contaminants. Irradiation of 20mg samples of grains with diameter of 20-50μm in the thermal neutron flux of 1.7×10(14)cm(-2)s(-1) at the core of MARIA research nuclear reactor allowed to obtain microspheres labelled with the (90)Y isotope on the way of the nuclear reaction (89)Y(n, ɤ)(90)Y. Specific activity of irradiated microspheres has been determined by application of absolute triple to double coincidence ratio method (TDCR) and has been evaluated at 190MBq/mg Y. (90)Y microspheres prepared by the proposed technique can be regarded as a promising medical material for radioembolization of liver malignancies.

  12. Simulation of a 32P Sourcewire and a 90Sr/90Y Sourcetrain Using MCNP4b and EGS4

    NASA Astrophysics Data System (ADS)

    Todorovic, M.; Cremers, F.; Albers, D.; Schmidt, R.

    The two simulated sources, the 32P sourcewire and the 90Sr/90Y sourcetrain, are parts of catheter-based systems developed for vascular brachytherapy. Percutaneous transluminal coronary angioplasty (PTCA) is a widely accepted therapy for symptomatic coronary disease, but within the first 6 months often restenosis occur. The intracoronary brachytherapy is a new method to help avoiding restenosis [1].

  13. Dosimetric comparison of {sup 90}Y, {sup 32}P, and {sup 186}Re radiocolloids in craniopharyngioma treatments

    SciTech Connect

    Sadeghi, Mahdi; Karimi, Elham; Hosseini, S. Hamed

    2009-11-15

    Purpose: In the radionuclide treatment of some forms of brain tumors such as craniopharyngiomas, the selection of the appropriate radionuclide for therapy is a key element in treatment planning. The aim was to study the influence by considering the beta-emitter radionuclide dose rate in an intracranial cyst. Methods: Dosimetry was performed using the MCNP4C radiation transport code. Analytical dosimetry was additionally performed using the Loevinger and the Berger formulas in the MATLAB software. Each result was compared under identical conditions. The advantages and disadvantages of using {sup 90}Y versus {sup 32}P and {sup 186}Re were investigated. Results: The dose rate at the inner surface of the cyst wall was estimated to be 400 mGy/h for a 1 MBq/ml concentration of {sup 90}Y. Under identical conditions of treatment, the corresponding dose rates were 300 mGy/h for {sup 32}P and 160 mGy/h for {sup 186}Re. For a well-defined cyst radius and identical wall thickness, higher dose rates resulted for {sup 90}Y. Conclusions: To achieve the same radiological burden, the required amount of physical activity of injectable solution is lower for {sup 32}P. This is found to be a consequence of both the radionuclide physical half-life and the pattern of energy deposition from the emitted radiation. According to the half-life and dose-rate results, {sup 90}Y would be a good substitute for {sup 32}P.

  14. Performance of thin CaSO4:Dy pellets for calibration of a Sr90+Y90 source

    NASA Astrophysics Data System (ADS)

    Oliveira, M. L.; Caldas, L. V. E.

    2007-09-01

    Because of the radionuclide long half-life, Sr90+Y90, plane or concave sources, utilized in brachytherapy, have to be calibrated initially by the manufacturer and then routinely while they are utilized. Plane applicators can be calibrated against a conventional extrapolation chamber, but concave sources, because of their geometry, should be calibrated using relative dosimeters, as thermoluminescent (TL) materials. Thin CaSO4:Dy pellets are produced at IPEN specially for beta radiation detection. Previous works showed the feasibility of this material in the dosimetry of Sr90+Y90 sources in a wide range of absorbed dose in air. The aim of this work was to study the usefulness of these pellets for the calibration of a Sr90+Y90 concave applicator. To reach this objective, a special phantom was designed and manufactured in PTFE with semi spherical geometry. Because of the dependence of the TL response on the mass of the pellet, the response of each pellet was normalized by its mass in order to reduce the dispersion on TL response. Important characteristics of this material were obtained in reference of a standard Sr90+Y90 source, and the pellets were calibrated against a plane applicator; then they were utilized to calibrate the concave applicator.

  15. Synthesis and Evaluation of a New Bifunctional NETA Chelate for Molecular Targeted Radiotherapy Using 90Y or 177Lu

    PubMed Central

    Kang, Chi Soo; Chen, Yunwei; Lee, Hyunbeom; Liu, Dijie; Sun, Xiang; Kweon, Junghun; Lewis, Michael R.; Chong, Hyun-Soon

    2015-01-01

    Introduction Therapeutic potential of β-emitting cytotoxic radionuclides 90Y and 177Lu have been demonstrated in numerous preclinical and clinical trials. A bifunctional chelate that can effectively complex with the radioisotopes is a critical component for molecular targeted radiotherapy 90Y and 177Lu. A new bifunctional chelate 5p-C-NETA with a relatively long alkyl spacer between the chelating backbone and the functional unit for conjugation to a tumor targeting moiety was synthesized. 5p-C-NETA was conjugated to a model targeting moiety, a cyclic Arg-Gly-Asp-D-Tyr-Lys (RGDyK) peptide binding integrin αvβ3 protein overexpressed on various cancers. 5p-C-NETA was conjugated to c(RGDyK) peptide and evaluated for potential use in molecular targeted radiotherapy of 90Y and 177Lu. Methods 5p-C-NETA conjugated with c(RGDyK) was evaluated in vitro for radiolabeling, serum stability, binding affinity, and the result of the in vitro studies of 5p-C-NETA-c(RGDyK) was compared to that of 3p-CNETA-c(RGDyK). 177Lu-5p-C-NETA-c(RGDyK) was further evaluated for in vivo biodistribution using gliobastoma bearing mice. Result The new chelate rapidly and tightly bound to a cytotoxic radioisotope for cancer therapy, 90Y or 177Lu with excellent radiolabeling efficiency and maximum specific activity under mild condition (>99%, RT, <1 min). 90Y- and 177Lu-radiolabeled complexes of the new chelator remained stable in human serum without any loss of the radiolanthanide for 14 days. Introduction of the tumor targeting RGD moiety to the new chelator made little impact on complexation kinetics and stability with 90Y or 177Lu. 177Lu-radiolabeled 5p-C-NETA-c(RGDyK) conjugate was shown to target tumors in mice and produced a favorable in vivo stability profile. Conclusion The results of in vitro and in vivo evaluation suggest that 5p-C-NETA is an effective bifunctional chelate of 90Y and 177Lu that can be applied for generation of versatile molecular targeted radiopharmaceuticals. PMID

  16. Activity measurements of 18F and 90Y with commercial radionuclide calibrators for nuclear medicine in Switzerland.

    PubMed

    Caffari, Yvan; Spring, Philippe; Bailat, Claude; Nedjadi, Youcef; Bochud, François

    2010-01-01

    The activity of radiopharmaceuticals in nuclear medicine is measured before patient injection with radionuclide calibrators. In Switzerland, the general requirements for quality controls are defined in a federal ordinance and a directive of the Federal Office of Metrology (METAS) which require each instrument to be verified. A set of three gamma sources (Co-57, Cs-137 and Co-60) is used to verify the response of radionuclide calibrators in the gamma energy range of their use. A beta source, a mixture of (90)Sr and (90)Y in secular equilibrium, is used as well. Manufacturers are responsible for the calibration factors. The main goal of the study was to monitor the validity of the calibration factors by using two sources: a (90)Sr/(90)Y source and a (18)F source. The three types of commercial radionuclide calibrators tested do not have a calibration factor for the mixture but only for (90)Y. Activity measurements of a (90)Sr/(90)Y source with the (90)Y calibration factor are performed in order to correct for the extra-contribution of (90)Sr. The value of the correction factor was found to be 1.113 whereas Monte Carlo simulations of the radionuclide calibrators estimate the correction factor to be 1.117. Measurements with (18)F sources in a specific geometry are also performed. Since this radionuclide is widely used in Swiss hospitals equipped with PET and PET-CT, the metrology of the (18)F is very important. The (18)F response normalized to the (137)Cs response shows that the difference with a reference value does not exceed 3% for the three types of radionuclide calibrators.

  17. 90Y-Labeled Anti-ROBO1 Monoclonal Antibody Exhibits Antitumor Activity against Small Cell Lung Cancer Xenografts

    PubMed Central

    Fujiwara, Kentaro; Koyama, Keitaro; Suga, Kosuke; Ikemura, Masako; Saito, Yasutaka; Hino, Akihiro; Iwanari, Hiroko; Kusano-Arai, Osamu; Mitsui, Kenichi; Kasahara, Hiroyuki; Fukayama, Masashi; Kodama, Tatsuhiko; Hamakubo, Takao; Momose, Toshimitsu

    2015-01-01

    Introduction ROBO1 is a membrane protein that contributes to tumor metastasis and angiogenesis. We previously reported that 90Y-labeled anti-ROBO1 monoclonal antibody (90Y-anti-ROBO1 IgG) showed an antitumor effect against ROBO1-positive tumors. In this study, we performed a biodistribution study and radioimmunotherapy (RIT) against ROBO1-positive small cell lung cancer (SCLC) models. Methods For the biodistribution study, 111In-labeled anti-ROBO1 monoclonal antibody (111In-anti-ROBO1 IgG) was injected into ROBO1-positive SCLC xenograft mice via the tail vein. To evaluate antitumor effects, an RIT study was performed, and SCLC xenograft mice were treated with 90Y-anti-ROBO1 IgG. Tumor volume and body weight were periodically measured throughout the experiments. The tumors and organs of mice were then collected, and a pathological analysis was carried out. Results As a result of the biodistribution study, we observed tumor uptake of 111In-anti-ROBO1 IgG. The liver, kidney, spleen, and lung showed comparably high accumulation of 111In-labeled anti-ROBO1. In the RIT study, 90Y-anti-ROBO1 IgG significantly reduced tumor volume compared with baseline. Pathological analyses of tumors revealed coagulation necrosis and fatal degeneration of tumor cells, significant reduction in the number of Ki-67-positive cells, and an increase in the number of apoptotic cells. A transient reduction of hematopoietic cells was observed in the spleen, sternum, and femur. Conclusions These results suggest that RIT with 90Y-anti-ROBO1 IgG is a promising treatment for ROBO1-positive SCLC. PMID:26017283

  18. Bremsstrahlung dosimetric parameters of beta-emitting therapeutic radionuclides

    NASA Astrophysics Data System (ADS)

    Manjunatha, H. C.

    2016-03-01

    Dosimetric parameters such as efficiency of bremsstrahlung, probability of energy loss of beta during bremsstrahlung production, intensity and dose rate of high, medium and low-energy beta-emitting therapeutic radionuclides in different tissues of human organs are computed. These parameters are lower in adipose tissue than all other studied tissues. The efficiency, intensity and dose rate of bremsstrahlung increases with maximum energy of the beta nuclide (Emax) and modified atomic number (Zmod) of the target tissue. The estimated bremsstrahlung efficiency, intensity and dose rate are useful in the calculations of photon track-length distributions. These parameters are useful to determine the quality and quantity of the bremsstrahlung radiation (known as the source term). Precise estimation of this source term is very important in planning for radiotherapy and diagnosis.

  19. Bremsstrahlung spectra from atoms and ions at low relativistic energies

    NASA Astrophysics Data System (ADS)

    Avdonina, N. B.; Pratt, R. H.

    1999-09-01

    Analytic expressions for bremsstrahlung spectra from neutral atoms and ions, including the polarizational bremsstrahlung contribution in a stripped atom approximation, are developed for electron scattering at energies of 10-2000 keV. A modified Elwert factor and a simple higher Born correction are used for the Coulomb spectrum, with ordinary bremsstrahlung screening effects in ions and atoms adequately characterized in the non-relativistic Born approximation. In parallel with the development of this analytic description, new numerical results are obtained for ordinary bremsstrahlung from ions and from bare nuclei, appreciably extending the available data set which can be used to study dependences on element, ionicity, energy and the fraction of incident energy radiated. The accuracy of predictions with the analytic expressions is then determined by comparison with the full numerical relativistic partial-wave results for ordinary bremsstrahlung and with non-relativistic numerical results in the Born approximation or in partial waves for the polarizational amplitude.

  20. Vector dark matter annihilation with internal bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Bambhaniya, Gulab; Kumar, Jason; Marfatia, Danny; Nayak, Alekha C.; Tomar, Gaurav

    2017-03-01

    We consider scenarios in which the annihilation of self-conjugate spin-1 dark matter to a Standard Model fermion-antifermion final state is chirality suppressed, but where this suppression can be lifted by the emission of an additional photon via internal bremsstrahlung. We find that this scenario can only arise if the initial dark matter state is polarized, which can occur in the context of self-interacting dark matter. In particular, this is possible if the dark matter pair forms a bound state that decays to its ground state before the constituents annihilate. We show that the shape of the resulting photon spectrum is the same as for self-conjugate spin-0 and spin-1/2 dark matter, but the normalization is less heavily suppressed in the limit of heavy mediators.

  1. Diagnostics at the ELBE Bremsstrahlung Facility

    NASA Astrophysics Data System (ADS)

    Evthushenko, P.; Lehnert, U.; Michel, P.; Schilling, K. D.; Schurig, R.; Teichert, J.

    2004-11-01

    The ELBE (Electron Linear accelerator with high Brilliance and low Emittance) machine is currently under transition from commissioning to regular user operation. The linac produces electron beams up to 40 MeV and 1 mA (CW), which are used to generate various kinds of secondary radiation. While the IR-FEL and X-ray facilities are still under construction, comprehensive nuclear physics experiments have been conducted at the Bremsstrahlung facility. Both, to meet the experimenter's demands on beam quality, stability and reproducibility and to ensure a safe operation of the machine, several diagnostic elements were developed. These devices, including backward OTR viewers, radiator temperature diagnostics, stripline detectors to monitor the beam incidence angle on the radiator, and a four-quadrant loss monitor, were developed, installed, and tested. These devices are described and results are presented in this paper.

  2. Bremsstrahlung target optimization for reflex triodes

    SciTech Connect

    Swanekamp, S. B.; Weber, B. V.; Stephanakis, S. J.; Mosher, D.; Commisso, R. J.

    2008-08-15

    The anode (tantalum) foil thickness in a reflex triode was varied from 2.5 to 250 {mu}m to maximize the dose from bremsstrahlung produced by a 1 MV, 1 MA, 100 ns electron beam. Experiments and computer simulations show that the dose is maximized for a foil thickness of about 25 {mu}m, 1/18th of the electron range computed from the continuous slowing down approximation. For foils thicker than optimum, self-absorption in the foil attenuates 10-100 keV photons, reducing the dose. For foils thinner than optimum, the dose decreases as a result of electron migration to large radius. A simple formula that predicts the optimum thickness as a function of the beam current and voltage is derived that should be applicable to a large range of experimental parameters.

  3. Safety of {sup 90}Y Radioembolization in Patients Who Have Undergone Previous External Beam Radiation Therapy

    SciTech Connect

    Lam, Marnix G.E.H.; Abdelmaksoud, Mohamed H.K.; Chang, Daniel T.; Eclov, Neville C.; Chung, Melody P.; Koong, Albert C.; Louie, John D.; Sze, Daniel Y.

    2013-10-01

    Purpose: Previous external beam radiation therapy (EBRT) is theoretically contraindicated for yttrium-90 ({sup 90}Y) radioembolization (RE) because the liver has a lifetime tolerance to radiation before becoming vulnerable to radiation-induced liver disease. We analyzed the safety of RE as salvage treatment in patients who had previously undergone EBRT. Methods and Materials: Between June 2004 and December 2010, a total of 31 patients who had previously undergone EBRT were treated with RE. Three-dimensional treatment planning with dose–volume histogram (DVH) analysis of the liver was used to calculate the EBRT liver dose. Liver-related toxicities including RE-induced liver disease (REILD) were reviewed and classified according to Common Terminology Criteria for Adverse Events version 4.02. Results: The mean EBRT and RE liver doses were 4.40 Gy (range, 0-23.13 Gy) and 57.9 Gy (range, 27.0-125.9 Gy), respectively. Patients who experienced hepatotoxicity (≥grade2; n=12) had higher EBRT mean liver doses (7.96 ± 8.55 Gy vs 1.62 ± 3.39 Gy; P=.037), the only independent predictor in multivariate analysis. DVH analysis showed that the fraction of liver exposed to ≥30 Gy (V30) was the strongest predictor of hepatotoxicity (10.14% ± 12.75% vs 0.84% ± 3.24%; P=.006). All patients with V30 >13% experienced hepatotoxicity. Fatal REILD (n=2) occurred at the 2 highest EBRT mean liver doses (20.9 Gy and 23.1 Gy) but also at the highest cumulative liver doses (91.8 Gy and 149 Gy). Conclusions: Prior exposure of the liver to EBRT may lead to increased liver toxicity after RE treatment, depending on fractional liver exposure and dose level. The V30 was the strongest predictor of toxicity. RE appears to be safe for the treatment of hepatic malignancies only in patients who have had limited hepatic exposure to prior EBRT.

  4. A review of 3D image-based dosimetry, technical considerations and emerging perspectives in 90Y microsphere therapy

    PubMed Central

    O’ Doherty, Jim

    2016-01-01

    Yttrium-90 radioembolization (90Y-RE) is a well-established therapy for the treatment of hepatocellular carcinoma (HCC) and also of metastatic liver deposits from other malignancies. Nuclear Medicine and Cath Lab diagnostic imaging takes a pivotal role in the success of the treatment, and in order to fully exploit the efficacy of the technique and provide reliable quantitative dosimetry that are related to clinical endpoints in the era of personalized medicine, technical challenges in imaging need to be overcome. In this paper, the extensive literature of current 90Y-RE techniques and challenges facing it in terms of quantification and dosimetry are reviewed, with a focus on the current generation of 3D dosimetry techniques. Finally, new emerging techniques are reviewed which seek to overcome these challenges, such as high-resolution imaging, novel surgical procedures and the use of other radiopharmaceuticals for therapy and pre-therapeutic planning. PMID:27182449

  5. Pathologic response and microdosimetry of {sup 90}Y microspheres in man: Review of four explanted whole livers

    SciTech Connect

    Kennedy, Andrew S. . E-mail: akennedy@wakerad.com; Nutting, Charles; Coldwell, Douglas; Gaiser, James; Drachenberg, Cinthia

    2004-12-01

    Introduction: Radioactive microsphere {sup 90}Y therapy is increasingly used for primary and metastatic solid tumors in the liver. We present an analysis of 4 explanted livers previously treated with {sup 90}Y microsphere agents (glass or resin). One tumor nodule was analyzed with submillimeter three-dimensional microdosimetry. Methods and materials: Four patients received hepatic artery delivery of {sup 90}Y microspheres for unresectable hepatocellular and colon cancers. Whole livers were explanted as part of lifesaving cadaveric transplant in 2 patients with hepatoma. These patients had received glass microspheres as a procedural bridge to transplant. Autopsy was performed on 2 patients with colon cancer who died of progressive metastatic disease and who had been treated with resin microspheres. Complete pathologic review was performed on each whole liver, including estimation of the response of the tumor to therapy, distribution of microspheres in the tumor and normal liver tissues, and normal-tissue radiation response. A biopsy taken from the edge of a tumor nodule was sectioned serially for three-dimensional radiation dosimetry analyses. Three-dimensional microsphere coordinates within the biopsy specimen were used to calculate dosage using a three-dimensional dose kernel. Isodose coverage of tumor and normal liver areas and total dose delivered were determined. Results: Preferential and heterogeneous deposition of microspheres was noted at the edge of tumor nodules compared with the center portion of the tumor or normal liver parenchyma. Both glass and resin microspheres delivered high cumulative doses to the tumor, which varied from 100 Gy to more than 3000 Gy. No veno-occlusive disease or widespread radiation hepatitis was seen. Conclusion: Microsphere ({sup 90}Y) therapy delivers high numbers of spheres with resulting high total doses of radiation, preferentially in the periphery of tumors. Normal liver parenchyma showed little radiation effect away from

  6. Magnetically directed poly(lactic acid) [sup 90]Y-microspheres: Novel agents for targeted intracavitary radiotherapy

    SciTech Connect

    Haefeli, U.O.; Sweeney, S.M.; Beresford, B.A.; Sim, E.H.; Macklis, R.M. . Joint Center for Radiation Therapy)

    1994-08-01

    High energy [beta]-emitting radioisotopes like Yttrium-90 have a radiotoxic range of about one centimeter. For cancer treatment they must be brought near the tumor cells and kept there for as long as they are radioactive. The authors developed as carriers for the ionic form of [sup 90]Y a matrix-type polymeric drug delivery system, poly(lactic acid) (PLA) microspheres. This radiopharmaceutical could be selectively delivered to the target site after incorporating 10% Fe[sub 3]O[sub 4] which made the magnetic microspheres (MMS) responsive to an external magnetic field. Furthermore, MMS are biodegradable and slowly hydrolyze into physiologic lactic acid after the radioactivity is completely decayed. Previously prepared 10--40 [mu]m MMS were radiochemically loaded to high specific activity with [sup 90]Y at a pH of 5.7. Stability studies showed that approximately 95% of added [sup 90]Y is retained within the PLA matrix after 28 days (> 10 half-lives) at 37 C in serum, and electron microscopy showed that the microspheres retained their characteristic morphologic appearance for the same time period. Cytotoxicity studies with SK-N-SH neuroblastoma cells growing in monolayer showed that the radiocytotoxicity of the microspheres could be directed magnetically to either kill or spare specific cell populations, thus making them of great interest for targeted intracavitary tumor therapy. The authors are currently optimizing this system for use in the treatment of neoplastic meningitis.

  7. Fractionated Radioimmunotherapy With 90Y-Clivatuzumab Tetraxetan and Low-Dose Gemcitabine Is Active in Advanced Pancreatic Cancer

    PubMed Central

    Ocean, Allyson J.; Pennington, Kenneth L.; Guarino, Michael J.; Sheikh, Arif; Bekaii-Saab, Tanios; Serafini, Aldo N.; Lee, Daniel; Sung, Max W.; Gulec, Seza A.; Goldsmith, Stanley J.; Manzone, Timothy; Holt, Michael; O’Neil, Bert H.; Hall, Nathan; Montero, Alberto J.; Kauh, John; Gold, David V.; Horne, Heather; Wegener, William A.; Goldenberg, David M.

    2014-01-01

    BACKGROUND It has been demonstrated that the humanized clivatuzumab tetraxetan (hPAM4) antibody targets pancreatic ductal carcinoma selectively. After a trial of radioimmunotherapy that determined the maximum tolerated dose of single-dose yttrium-90-labeled hPAM4 (90Y-hPAM4) and produced objective responses in patients with advanced pancreatic ductal carcinoma, the authors studied fractionated radioimmunotherapy combined with low-dose gemcitabine in this disease. METHODS Thirty-eight previously untreated patients (33 patients with stage IV disease and 5 patients with stage III disease) received gemcitabine 200 mg/m2 weekly for 4 weeks with 90Y-hPAM4 given weekly in Weeks 2, 3, and 4 (cycle 1), and the same cycle was repeated in 13 patients (cycles 2–4). In the first part of the study, 19 patients received escalating weekly 90Y doses of 6.5 mCi/m2, 9.0 mCi/m2, 12.0 mCi/m2, and 15.0 mCi/m2. In the second portion, 19 additional patients received weekly doses of 9.0 mCi/m2 or 12.0 mCi/m2. RESULTS Grade 3/4 thrombocytopenia or neutropenia (according to version 3.0 of the National Cancer Institute’s Common Terminology Criteria for Adverse Events) developed in 28 of 38 patients after cycle 1 and in all retreated patients; no grade >3 nonhematologic toxicities occurred. Fractionated dosing of cycle 1 allowed almost twice the radiation dose compared with single-dose radioimmunotherapy. The maximum tolerated dose of 90Y-hPAM4 was 12.0 mCi/m2 weekly for 3 weeks for cycle 1, with ≤9.0 mCi/m2 weekly for 3 weeks for subsequent cycles, and that dose will be used in future trials. Six patients (16%) had partial responses according to computed tomography-based Response Evaluation Criteria in Solid Tumors, and 16 patients (42%) had stabilization as their best response (58% disease control). The median overall survival was 7.7 months for all 38 patients, including 11.8 months for those who received repeated cycles (46% [6 of 13 patients] ≥1 year), with improved efficacy at

  8. Bremsstrahlung background in inelastic electron–nucleus collisions

    NASA Astrophysics Data System (ADS)

    Jakubassa-Amundsen, D. H.; Krugmann, A.

    2017-04-01

    Bremsstrahlung emission by relativistic electrons in collisions with medium heavy spin-zero nuclei is calculated within the plane-wave Born approximation. Coulomb distortion is estimated by a comparison with the Dirac partial-wave theory at energies up to 20 MeV. When integrated over the photon emission angle, the bremsstrahlung spectra help to explain the background of the nuclear excitation spectra in 150Nd (e,e\\prime ) reactions which were recently measured on an absolute scale.

  9. Inversion of bremsstrahlung spectra emitted by solar plasma

    NASA Astrophysics Data System (ADS)

    Piana, M.

    1994-08-01

    Bremsstrahlung radiation coming from the solar atmosphere is linked to the distribution function of electrons in the solar plasma through a Volterra equation of the first kind. We have assumed the Bethe-Heitler approximation for the bremsstrahlung cross section and we have applied the SVD method to the integral equation with discrete data. Using Tikhonov's regularisation technique, reconstructions of the electronic distribution functions have been obtained, both for simulated and real data.

  10. Analytic approximate radiation effects due to Bremsstrahlung

    SciTech Connect

    Ben-Zvi I.

    2012-02-01

    The purpose of this note is to provide analytic approximate expressions that can provide quick estimates of the various effects of the Bremsstrahlung radiation produced relatively low energy electrons, such as the dumping of the beam into the beam stop at the ERL or field emission in superconducting cavities. The purpose of this work is not to replace a dependable calculation or, better yet, a measurement under real conditions, but to provide a quick but approximate estimate for guidance purposes only. These effects include dose to personnel, ozone generation in the air volume exposed to the radiation, hydrogen generation in the beam dump water cooling system and radiation damage to near-by magnets. These expressions can be used for other purposes, but one should note that the electron beam energy range is limited. In these calculations the good range is from about 0.5 MeV to 10 MeV. To help in the application of this note, calculations are presented as a worked out example for the beam dump of the R&D Energy Recovery Linac.

  11. Hepatic Toxicity After Radioembolization of the Liver Using {sup 90}Y-Microspheres: Sequential Lobar Versus Whole Liver Approach

    SciTech Connect

    Seidensticker, Ricarda; Seidensticker, Max; Damm, Robert; Mohnike, Konrad; Schuette, Kerstin; Malfertheiner, Peter; Buskirk, Mark Van; Pech, Maciej; Amthauer, Holger; Ricke, Jens

    2012-10-15

    Purpose: {sup 90}Y-radioembolization (RE) is a promising technique for delivering high doses of radiation to liver tumors but may result in compromise of liver function. To gain further perspective, we evaluated the toxicity rates of sequential lobar versus 'whole liver' {sup 90}Y-radioembolization. Methods: Thirty-four patients with liver malignancy in noncirrhotic livers were included; {sup 90}Y-radioembolization was performed as either whole liver or sequential lobar treatment in 17 patients each. Standard clinical and liver specific laboratory parameters as well as MR imaging before treatment and at follow-up (6 and 12 weeks) after radioembolization were evaluated for toxicity using the Common Terminology Criteria for Adverse Events (CTCAE). Volumetry of the liver, tumor, and spleen and measurement of portal vein diameter also were performed. Results: Three months after whole liver RE, 14 liver-related grade 3/4 events were recorded versus 2 events after sequential lobar treatment (P < 0.05). Three patients treated with whole liver RE suffered from radioembolization-induced liver disease (REILD). Pathological increases in bilirubin at 3 months were observed for the whole liver group only (52.3 vs. 18.7 {mu}mol/l, P = 0.012). Total liver volume did not change significantly in either group, but shrinkage of the initially treated hepatic lobe with compensatory hypertrophy of the subsequently treated lobe was observed in the sequential lobar group (P < 0.05). Portal vein diameter increased significantly in whole liver-treated patients only (+17% vs. +6.6%, P = 0.043). Conclusions: Noncirrhotic patients undergoing sequential lobar radioembolization had less hepatic toxicity compared to whole liver embolization. The sequential approach should be the preferred strategy.

  12. WE-AB-204-01: Performance Characterization of Regularized-Reconstruction Algorithm for 90Y PET/CT Images

    SciTech Connect

    Siman, W; Kappadath, S; Mawlawi, O

    2015-06-15

    Purpose: {sup 90}Y PET/CT imaging and quantification have recently been suggested as an approach of treatment verification. However, due to low positron yield (32ppm), the {sup 90}Y-PET/CT images are very noisy. Iterative reconstruction techniques that employ regularization, e.g. block sequential regularized expectation maximization (BSREM) algorithm (recently implemented on GE scanners – QClear™), has the potential to increase quantitative accuracy with lower noise penalty compared to OSEM. Our aim is to investigate the performance of RR algorithms in {sup 90}Y PET/CT studies. Methods: A NEMA IEC phantom filled with 3GBq {sup 90}YCl{sub 2} (to simulate patient treatment) was imaged on GE-D690 for 1800s/bed. The sphere-to-background ratio of 7. The data were reconstructed using OSEM and BSREM with PSF modeling and TOF correction while varying the iterations (IT) from 1–6 with fixed 24subsets. For BSREM, the edge-preservation parameter (γ ) was 2 and the penalty-parameters (β) was varied 350–950. In all cases a post-reconstruction filter of 5.2mm (2pixel) transaxial and standard z-axis were used. Sphere average activity concentration (AC) and background standard deviation (SD) were then calculated from VOIs drawn in the spheres and background. Results: Increasing IT from 1to6, the %SD in OSEM increased from 30% to 80%, whereas %SD in BSREM images increased by <5% for all βs. BSREM with β=350 didn’t offer any improvement over OSEM (convergence of mean achieved at 2 IT, in this study). Increasing β from 350 to 950 reduced the AC accuracy of small spheres (<20mm) by 10% and noise from 40% to 20%, which resulted in CNR increase from 11 to 17. Conclusion: In count-limited studies such as {sup 90}Y PET/CT, BSREM can be used to suppress image noise and increase CNR at the expense of a relatively small decrease of quantitative accuracy. The BSREM parameters need to be optimized for each study depending on the radionuclides and count densities. Research

  13. Inhibiting the effect of 90Sr-90Y ophthalmic applicators on rat corneal neovascularization induced by sutures

    PubMed Central

    Zhou, Hong-Yan; Wang, Shuang; Zhang, Hong; Wang, Ling; Zhang, Wen-Song

    2016-01-01

    AIM To investigate a practical technique used to inhibit corneal angiogenesis with a 90Sr-90Y ophthalmic applicator. METHODS A 90Sr-90Y ophthalmic applicator was detected with a radioactive nuclide application treatment healthy protection standard. The applicator used was produced through medical dosimetry research; it had a concave applicator add measured the applicator temperature, serviceable humidity range, applicator appearance status, applicator radiation homogeneity, radioautography, and radiological safety of the original applicator surface. A vessel model was established using newborn rats, with sutures around the corneal limbus. Corneal neovascularization (CNV) were observed with a slit lamp. The new vessel length and response area were measured. RESULTS Low-dose radiation can inhibit CNV after corneal sutures. The absorbed dose of the applicator (0.046 Gy/s) was safe for the treatment of it. The lengths of new vessels and the areas of new vessels were lower than the new born vessel rat group (P<0.01). CONCLUSION The optimal radiation dose emitting from the applicator can be safe and potentially used in humans. PMID:27672586

  14. The effect of heat treatment on amorphous Fe74Zr19Ta7 and Fe90Y10 alloys

    NASA Astrophysics Data System (ADS)

    Prater, J. T.; Merz, M. D.

    1981-03-01

    Magnetic measurements are reported for two iron-based amorphous alloys: Fe90Y10 and Fe74Zr19Ta7. Each is prepared by sputter deposition. X-tay diffraction is used to established the amorphous structure and X-ray fluorescence analysis to confirm the composition. Fe74Zr19Ta7 has a Curie temperature of 195 K and a crystallization temperature of 733 K (460 °C). Annealing studies on Fe74Zr19Ta7 indicate that this alloy does not show the dramatic increases in Curie temperature that are commonly observed in amorphous alloys that contain metalloid elements. Rather, this alloy exhibits small irreversible decreases in the Curie temperature following heat treatments up to 733 K (460 °C), the crystallization temperature. The amorphous Fe90Y10 alloy shows only short range order and has a large anisotropy field that prevents the saturation of the magnetic moment in a 10 kOe field at 78 K. The anisotropy decreases upon crystallization to a bcc iron structure, but ferromagnetism is observed only after annealing the alloy at elevated temperatures.

  15. Dosimetry of a (90)Y-hydroxide liquid brachytherapy treatment approach to canine osteosarcoma using PET/CT.

    PubMed

    Zhou, Jien Jie; Gonzalez, Arnulfo; Lenox, Mark W; Fossum, Theresa W; Frank, R Keith; Simon, Jaime; Stearns, Stan; Ruoff, Catherine M; Wendt, Richard E; Akabani, Gamal

    2015-03-01

    A new treatment strategy based on direct injections of (90)Y-hydroxide into the tumor bed in dogs with osteosarcoma was studied. Direct injections of the radiopharmaceutical into the tumor bed were made according to a pretreatment plan established using (18)F-FDG images. Using a special drill, cannulas were inserted going through tissue, tumor and bone. Using these cannulas, direct injections of the radiopharmaceutical were made. The in vivo biodistribution of (90)Y-hydroxide and the anatomical tumor bed were imaged using a time-of-flight (TOF) PET/CT scanner. The material properties of the tissues were estimated from corresponding CT numbers using an electron-density calibration. Radiation absorbed dose estimates were calculated using Monte Carlo methods where the biodistribution of the pharmaceutical from PET images was sampled using a collapsing 3-D rejection technique. Dose distributions in the tumor bed and surrounding tissues were calculated, showing significant heterogeneity with multiple hot spots at injection sites. Dose volume histograms showed that approximately 33.9% of bone and tumor and 70.2% of bone marrow and trabecular bone received an absorbed dose over 200Gy; approximately 3.2% of bone and tumor and 31.0% of bone marrow and trabecular bone received a total dose of over 1000Gy.

  16. Organ doses from hepatic radioembolization with 90Y, 153Sm, 166Ho and 177Lu: A Monte Carlo simulation study using Geant4

    NASA Astrophysics Data System (ADS)

    Hashikin, N. A. A.; Yeong, C. H.; Guatelli, S.; Abdullah, B. J. J.; Ng, K. H.; Malaroda, A.; Rosenfeld, A. B.; Perkins, A. C.

    2016-03-01

    90Y-radioembolization is a palliative treatment for liver cancer. 90Y decays via beta emission, making imaging difficult due to absence of gamma radiation. Since post-procedure imaging is crucial, several theranostic radionuclides have been explored as alternatives. However, exposures to gamma radiation throughout the treatment caused concern for the organs near the liver. Geant4 Monte Carlo simulation using MIRD Pamphlet 5 reference phantom was carried out. A spherical tumour with 4.3cm radius was modelled within the liver. 1.82GBq of 90Y sources were isotropically distributed within the tumour, with no extrahepatic shunting. The simulation was repeated with 153Sm, 166Ho and 177Lu. The estimated tumour doses for all radionuclides were 262.9Gy. Tumour dose equivalent to 1.82GBq 90Y can be achieved with 8.32, 5.83, and 4.44GBq for 153Sm, 166Ho and 177Lu, respectively. Normal liver doses by the other radionuclides were lower than 90Y, hence beneficial for normal tissue sparing. The organ doses from 153Sm and 177Lu were relatively higher due to higher gamma energy, but were still well below 1Gy. 166Ho, 177Lu and 153Sm offer useful gamma emission for post-procedure imaging. They show potential as 90Y substitutes, delivering comparable tumour doses, lower normal liver doses and other organs doses far below the tolerance limit.

  17. The Stonehenge technique. A method for aligning coherent bremsstrahlung radiators

    NASA Astrophysics Data System (ADS)

    Livingston, Ken

    2009-05-01

    This paper describes a technique for the alignment of crystal radiators used to produce high energy, linearly polarized photons via coherent bremsstrahlung scattering at electron beam facilities. In these experiments the crystal is mounted on a goniometer which is used to adjust its orientation relative to the electron beam. The angles and equations which relate the crystal lattice, goniometer and electron beam direction are presented here, and the method of alignment is illustrated with data taken at MAMI (the Mainz microtron). A practical guide to setting up a coherent bremsstrahlung facility and installing new crystals using this technique is also included.

  18. Jovian bremsstrahlung X-rays - A Ulysses prediction

    NASA Technical Reports Server (NTRS)

    Waite, J. H., Jr.; Boice, D. C.; Hurley, K. C.; Stern, S. A.; Sommer, M.

    1992-01-01

    Modeling results reported here show that precipitating auroral electrons with sufficient energy to be consistent with the Voyager UVS observations produce bremsstrahlung X-rays with sufficient energy and intensity to be detected by the Solar Flare X-ray and Cosmic-Ray-Burst Instrument on board the Ulysses spacecraft. The detection of such bremsstrahlung X-rays at Jupiter would provide strong evidence for the electron-precipitation mechanism, although it does not rule out the possibility of some heavy ion involvement, and thus makes a significant contribution toward solving the mystery of the Jovian aurora.

  19. Efficacy of 90Y ibritumomab-tiuxetan treatment in a case of resistant gastric MALT non-Hodgkin’s lymphoma

    PubMed Central

    Ferrucci, PF; Vanazzi, A; Crosta, C; Pruneri, G; Grana, C; Bartolomei, M; Paganelli, G; Martinelli, G

    2008-01-01

    Treatment modalities for resistant/relapsing gastric mucosa associated lymphoid tissue (MALT) non-Hodgkin’s lymphoma (NHL) are not yet well standardized. In the past, most patients were treated surgically with a gastrectomy, while, more recently, radiotherapy and systemic approaches (chemotherapy and immunotherapy) have been used with improving results. Here, we report the case of a patient affected by MALT NHL resistant to antibiotics, chemotherapy and immunotherapy, who achieved a durable complete remission after radio-immunotherapy treatment with Zevalin (90Y ibritumomab-tiuxetan), administered in a single-standard dose. This observation must be confirmed on a larger series but suggests that radio-immunotherapy may be a valid approach in treating relapsing MALT NHL patients, or those resistant to conventional therapies, so avoiding more aggressive and toxic approaches. PMID:22275968

  20. Radioimmunotherapy of breast cancer metastases with alpha-particle emitter 225Ac: comparing efficacy with 213Bi and 90Y.

    PubMed

    Song, Hong; Hobbs, Robert F; Vajravelu, Ravy; Huso, David L; Esaias, Caroline; Apostolidis, Christos; Morgenstern, Alfred; Sgouros, George

    2009-12-01

    alpha-Particles are suitable to treat cancer micrometastases because of their short range and very high linear energy transfer. alpha-Particle emitter (213)Bi-based radioimmunotherapy has shown efficacy in a variety of metastatic animal cancer models, such as breast, ovarian, and prostate cancers. Its clinical implementation, however, is challenging due to the limited supply of (225)Ac, high technical requirement to prepare radioimmunoconjugate with very short half-life (T(1/2) = 45.6 min) on site, and prohibitive cost. In this study, we investigated the efficacy of the alpha-particle emitter (225)Ac, parent of (213)Bi, in a mouse model of breast cancer metastases. A single administration of (225)Ac (400 nCi)-labeled anti-rat HER-2/neu monoclonal antibody (7.16.4) completely eradicated breast cancer lung micrometastases in approximately 67% of HER-2/neu transgenic mice and led to long-term survival of these mice for up to 1 year. Treatment with (225)Ac-7.16.4 is significantly more effective than (213)Bi-7.16.4 (120 microCi; median survival, 61 days; P = 0.001) and (90)Y-7.16.4 (120 microCi; median survival, 50 days; P < 0.001) as well as untreated control (median survival, 41 days; P < 0.0001). Dosimetric analysis showed that (225)Ac-treated metastases received a total dose of 9.6 Gy, significantly higher than 2.0 Gy from (213)Bi and 2.4 Gy from (90)Y. Biodistribution studies revealed that (225)Ac daughters, (221)Fr and (213)Bi, accumulated in kidneys and probably contributed to the long-term renal toxicity observed in surviving mice. These data suggest (225)Ac-labeled anti-HER-2/neu monoclonal antibody could significantly prolong survival in HER-2/neu-positive metastatic breast cancer patients.

  1. Hepatic falciform ligament Tc-99m-macroaggregated albumin activity on SPECT/CT prior to Yttrium-90 microsphere radioembolization: prophylactic measures to prevent non-target microsphere localization via patent hepatic falciform arteries.

    PubMed

    Kao, Yung Hsiang; Tan, Andrew E H; Khoo, Li Ser; Lo, Richard H G; Chow, Pierce K H; Goh, Anthony S W

    2011-06-01

    Yttrium-90 (Y-90) selective internal radiation therapy (SIRT) is increasingly used to treat inoperable hepatocellular carcinoma. We describe two patients where hepatic falciform ligament Technetium-99m-macroaggregated albumin (Tc-99m-MAA) activity was identified on single photon emission computed tomography with integrated low-dose CT (SPECT/CT) scan during pre-therapy planning, and the steps taken to prevent radiation dermatitis. The first patient underwent prophylactic coil embolization of the patent hepatic falciform artery; the second patient underwent super-selective infusion of Y-90 resin microspheres to avoid the patent hepatic falciform artery. The incidence of falciform ligament Tc-99m-MAA activity detected on SPECT/CT at our institution is 10%. Tc-99m-MAA SPECT/CT scan provides valuable diagnostic information for treatment planning prior to Y-90 SIRT.

  2. Observation of the muon inner bremsstrahlung at LEP1

    NASA Astrophysics Data System (ADS)

    Abdallah, J.; Abreu, P.; Adam, W.; Adzic, P.; Albrecht, T.; Alemany-Fernandez, R.; Allmendinger, T.; Allport, P. P.; Amaldi, U.; Amapane, N.; Amato, S.; Anashkin, E.; Andreazza, A.; Andringa, S.; Anjos, N.; Antilogus, P.; Apel, W.-D.; Arnoud, Y.; Ask, S.; Asman, B.; Augustin, J. E.; Augustinus, A.; Baillon, P.; Ballestrero, A.; Bambade, P.; Barbier, R.; Bardin, D.; Barker, G. J.; Baroncelli, A.; Battaglia, M.; Baubillier, M.; Becks, K.-H.; Begalli, M.; Behrmann, A.; Ben-Haim, E.; Benekos, N.; Benvenuti, A.; Berat, C.; Berggren, M.; Bertrand, D.; Besancon, M.; Besson, N.; Bloch, D.; Blom, M.; Bluj, M.; Bonesini, M.; Boonekamp, M.; Booth, P. S. L.; Borisov, G.; Botner, O.; Bouquet, B.; Bowcock, T. J. V.; Boyko, I.; Bracko, M.; Brenner, R.; Brodet, E.; Bruckman, P.; Brunet, J. M.; Buschbeck, B.; Buschmann, P.; Calvi, M.; Camporesi, T.; Canale, V.; Carena, F.; Castro, N.; Cavallo, F.; Chapkin, M.; Charpentier, Ph.; Checchia, P.; Chierici, R.; Chliapnikov, P.; Chudoba, J.; Chung, S. U.; Cieslik, K.; Collins, P.; Contri, R.; Cosme, G.; Cossutti, F.; Costa, M. J.; Crennell, D.; Cuevas, J.; D'Hondt, J.; da Silva, T.; da Silva, W.; Della Ricca, G.; de Angelis, A.; de Boer, W.; de Clercq, C.; de Lotto, B.; de Maria, N.; de Min, A.; de Paula, L.; di Ciaccio, L.; di Simone, A.; Doroba, K.; Drees, J.; Eigen, G.; Ekelof, T.; Ellert, M.; Elsing, M.; Espirito Santo, M. C.; Fanourakis, G.; Fassouliotis, D.; Feindt, M.; Fernandez, J.; Ferrer, A.; Ferro, F.; Flagmeyer, U.; Foeth, H.; Fokitis, E.; Fulda-Quenzer, F.; Fuster, J.; Gandelman, M.; Garcia, C.; Gavillet, Ph.; Gazis, E.; Gokieli, R.; Golob, B.; Gomez-Ceballos, G.; Goncalves, P.; Graziani, E.; Grosdidier, G.; Grzelak, K.; Guy, J.; Haag, C.; Hallgren, A.; Hamacher, K.; Hamilton, K.; Haug, S.; Hauler, F.; Hedberg, V.; Hennecke, M.; Herr, H.; Hoffman, J.; Holmgren, S.-O.; Holt, P. J.; Houlden, M. A.; Jackson, J. N.; Jarlskog, G.; Jarry, P.; Jeans, D.; Johansson, E. K.; Jonsson, P.; Joram, C.; Jungermann, L.; Kapusta, F.; Katsanevas, S.; Katsoufis, E.; Kernel, G.; Kersevan, B. P.; Kerzel, U.; King, B. T.; Kjaer, N. J.; Kluit, P.; Kokkinias, P.; Kourkoumelis, C.; Kouznetsov, O.; Krumstein, Z.; Kucharczyk, M.; Lamsa, J.; Leder, G.; Ledroit, F.; Leinonen, L.; Leitner, R.; Lemonne, J.; Lepeltier, V.; Lesiak, T.; Liebig, W.; Liko, D.; Lipniacka, A.; Lopes, J. H.; Lopez, J. M.; Loukas, D.; Lutz, P.; Lyons, L.; MacNaughton, J.; Malek, A.; Maltezos, S.; Mandl, F.; Marco, J.; Marco, R.; Marechal, B.; Margoni, M.; Marin, J.-C.; Mariotti, C.; Markou, A.; Martinez-Rivero, C.; Masik, J.; Mastroyiannopoulos, N.; Matorras, F.; Matteuzzi, C.; Mazzucato, F.; Mazzucato, M.; Mc Nulty, R.; Meroni, C.; Migliore, E.; Mitaroff, W.; Mjoernmark, U.; Moa, T.; Moch, M.; Moenig, K.; Monge, R.; Montenegro, J.; Moraes, D.; Moreno, S.; Morettini, P.; Mueller, U.; Muenich, K.; Mulders, M.; Mundim, L.; Murray, W.; Muryn, B.; Myatt, G.; Myklebust, T.; Nassiakou, M.; Navarria, F.; Nawrocki, K.; Nicolaidou, R.; Nikolenko, M.; Oblakowska-Mucha, A.; Obraztsov, V.; Olshevski, A.; Onofre, A.; Orava, R.; Osterberg, K.; Ouraou, A.; Oyanguren, A.; Paganoni, M.; Paiano, S.; Palacios, J. P.; Palka, H.; Papadopoulou, Th. D.; Pape, L.; Parkes, C.; Parodi, F.; Parzefall, U.; Passeri, A.; Passon, O.; Peralta, L.; Perepelitsa, V.; Perrotta, A.; Petrolini, A.; Piedra, J.; Pieri, L.; Pierre, F.; Pimenta, M.; Piotto, E.; Podobnik, T.; Poireau, V.; Pol, M. E.; Polok, G.; Pozdniakov, V.; Pukhaeva, N.; Pullia, A.; Rames, J.; Read, A.; Rebecchi, P.; Rehn, J.; Reid, D.; Reinhardt, R.; Renton, P.; Richard, F.; Ridky, J.; Rivero, M.; Rodriguez, D.; Romero, A.; Ronchese, P.; Roudeau, P.; Rovelli, T.; Ruhlmann-Kleider, V.; Ryabtchikov, D.; Sadovsky, A.; Salmi, L.; Salt, J.; Sander, C.; Savoy-Navarro, A.; Schwickerath, U.; Sekulin, R.; Siebel, M.; Sisakian, A.; Smadja, G.; Smirnova, O.; Sokolov, A.; Sopczak, A.; Sosnowski, R.; Spassov, T.; Stanitzki, M.; Stocchi, A.; Strauss, J.; Stugu, B.; Szczekowski, M.; Szeptycka, M.; Szumlak, T.; Tabarelli, T.; Tegenfeldt, F.; Timmermans, J.; Tkatchev, L.; Tobin, M.; Todorovova, S.; Tome, B.; Tonazzo, A.; Tortosa, P.; Travnicek, P.; Treille, D.; Tristram, G.; Trochimczuk, M.; Troncon, C.; Turluer, M.-L.; Tyapkin, I. A.; Tyapkin, P.; Tzamarias, S.; Uvarov, V.; Valenti, G.; van Dam, P.; van Eldik, J.; van Remortel, N.; van Vulpen, I.; Vegni, G.; Veloso, F.; Venus, W.; Verdier, P.; Verzi, V.; Vilanova, D.; Vitale, L.; Vrba, V.; Wahlen, H.; Washbrook, A. J.; Weiser, C.; Wicke, D.; Wickens, J.; Wilkinson, G.; Winter, M.; Witek, M.; Yushchenko, O.; Zalewska, A.; Zalewski, P.; Zavrtanik, D.; Zhuravlov, V.; Zimin, N. I.; Zintchenko, A.; Zupan, M.

    2008-10-01

    Muon bremsstrahlung photons converted in front of the DELPHI main tracker (TPC) in dimuon events at LEP1 were studied in two photon kinematic ranges: 0.2< E γ ≤1 GeV and transverse momentum with respect to the parent muon p T <40 MeV/ c, and 1< E γ ≤10 GeV and p T <80 MeV/ c. A good agreement of the observed photon rate with predictions from QED for the muon inner bremsstrahlung was found, contrary to the anomalous soft photon excess that has been observed recently in hadronic Z 0 decays. The obtained ratios of the observed signal to the predicted level of the muon bremsstrahlung are 1.06±0.12±0.07 in the photon energy range 0.2< E γ ≤1 GeV and 1.04±0.09±0.12 in the photon energy range 1< E γ ≤10 GeV. The bremsstrahlung dead cone is observed for the first time in the direct photon production at LEP.

  3. Organ volume estimation using SPECT

    SciTech Connect

    Zaidi, H.

    1996-06-01

    Knowledge of in vivo thyroid volume has both diagnostic and therapeutic importance and could lead to a more precise quantification of absolute activity contained in the thyroid gland. In order to improve single-photon emission computed tomography (SPECT) quantitation, attenuation correction was performed according to Chang`s algorithm. The dual window method was used for scatter subtraction. The author used a Monte Carlo simulation of the SPECT system to accurately determine the scatter multiplier factor k. Volume estimation using SPECT was performed by summing up the volume elements (voxels) lying within the contour of the object, determined by a fixed threshold and the gray level histogram (GLH) method. Thyroid phantom and patient studies were performed and the influence of (1) fixed thresholding, (2) automatic thresholding, (3) attenuation, (4) scatter, and (5) reconstruction filter were investigated. This study shows that accurate volume estimation of the thyroid gland is feasible when accurate corrections are performed. The relative error is within 7% for the GLH method combined with attenuation and scatter corrections.

  4. Lymphoma: evaluation with Ga-67 SPECT

    SciTech Connect

    Tumeh, S.S.; Rosenthal, D.S.; Kaplan, W.D.; English, R.J.; Holman, B.L.

    1987-07-01

    To determine the value of gallium-67 single photon emission computed tomography (SPECT) in imaging patients with lymphoma, the authors compared Ga-67 planar images and SPECT images in 40 consecutive patients, using radiologic examinations and/or medical records to confirm the presence or absence of disease. Thirty-three patients had Hodgkin disease, and seven had non-Hodgkin lymphoma. Fifty-four examinations were performed. Of 57 sites of lymphoma in the chest, planar imaging depicted 38, while SPECT depicted 55, resulting in sensitivities of 0.66 and 0.96 for planar and SPECT imaging, respectively. In eight sites, both modalities were truly negative, but SPECT was negative in four additional sites that were equivocal on planar imaging, resulting in specificities of 0.66 and 1.00 for planar and SPECT imaging, respectively. In the abdomen, the sensitivities of planar and SPECT imaging were 0.69 and 0.85, and the specificities 0.87 and 1.00, respectively. SPECT was more accurate in depicting foci of gallium-avid lymphoma in the chest and abdomen and in excluding disease when planar imaging was equivocal.

  5. C-SPECT - a Clinical Cardiac SPECT/Tct Platform: Design Concepts and Performance Potential

    PubMed Central

    Chang, Wei; Ordonez, Caesar E.; Liang, Haoning; Li, Yusheng; Liu, Jingai

    2013-01-01

    Because of scarcity of photons emitted from the heart, clinical cardiac SPECT imaging is mainly limited by photon statistics. The sub-optimal detection efficiency of current SPECT systems not only limits the quality of clinical cardiac SPECT imaging but also makes more advanced potential applications difficult to be realized. We propose a high-performance system platform - C-SPECT, which has its sampling geometry optimized for detection of emitted photons in quality and quantity. The C-SPECT has a stationary C-shaped gantry that surrounds the left-front side of a patient’s thorax. The stationary C-shaped collimator and detector systems in the gantry provide effective and efficient detection and sampling of photon emission. For cardiac imaging, the C-SPECT platform could achieve 2 to 4 times the system geometric efficiency of conventional SPECT systems at the same sampling resolution. This platform also includes an integrated transmission CT for attenuation correction. The ability of C-SPECT systems to perform sequential high-quality emission and transmission imaging could bring cost-effective high-performance to clinical imaging. In addition, a C-SPECT system could provide high detection efficiency to accommodate fast acquisition rate for gated and dynamic cardiac imaging. This paper describes the design concepts and performance potential of C-SPECT, and illustrates how these concepts can be implemented in a basic system. PMID:23885129

  6. Online measurement of dose and dose distribution at bremsstrahlung facilities

    NASA Astrophysics Data System (ADS)

    Auslender, V. L.; Bryazgin, A. A.; Bukin, A. D.; Voronin, L. A.; Lukin, A. N.; Sidorov, A. V.

    2004-09-01

    A real-time measurement system of the spatial dose distribution is developed and realized for monitoring the bremsstrahlung flow generated on X-ray target by 5 MeV 50 kW electron accelerator. The sensors of the system consist of semiconductor diodes. The beam target and electron accelerator (ILU-10) are briefly described. The practice of using the system in the experimental and start-up procedure is included.

  7. Scintillating fiber array for tagging post-bremsstrahlung electrons

    NASA Astrophysics Data System (ADS)

    Cole, Philip; Alef, Stefan; Reitz, Björn-Eric; Schmieden, Hartmut; Hannappel, Jürgen; Jude, Thomas; Sandri, Paolo Levi; BGO-OD Collaboration

    2016-03-01

    We seek to extract the kinematic fingerprints of baryon resonances by making use of a high-quality beam of linearly polarized photons at the BGO-OD experiment at ELSA (Bonn, German). We constructed a unique device for precisely determining the degree of polarization in the coherent bremsstrahlung peak. Deflection of post-bremsstrahlung electrons in the magnetic field of the photon tagger provides precise information on the energy and polarization of the bremsstrahlung photons. And thereby will constrain the overall kinematics of the final-state particles in all decay channels of the photoproduced baryon resonances. We designed, prototyped, built, calibrated, and have been operating a three-layered, multi-stranded, scintillating-fiber detector for ensuring the quality of the linearly polarization of the photon beam. The overlapping 2.00-mm scintillating fibers form an array giving ARGUS over 500 channels. The very befitting name harkens to the mythological all-seeing creature Argus Panoptes, the multi-eyed giant. Our work was supported through a Fulbright Scholarship Award and by the Deutsche Forschungsgemeinschaft through the Collaborative Research Center (Sonderforschungsbereich SFB/TR-16) of the universities in Bonn, Giessen and Bochum, Germany. NSF-PHY-1307340.

  8. Density effects on bremsstrahlung radiation in quantum plasmas

    NASA Astrophysics Data System (ADS)

    Akbari-Moghanjoughi, M.; Jung, Young-Dae

    2014-01-01

    In this paper, we investigate the effects of plasma number-density and quantum shielding of ions by degenerate electrons on the free-free and electron-atom bremsstrahlung radiation spectra in dense quantum plasmas for a wide range of plasma number-density and atomic-number of the constituent ions. We use previously reported results from the extended Shukla-Eliasson quantum-dressed ionic potential, which takes into account the relativistic degeneracy effect, the quantum statistical pressure, the electron-exchange correlations, the Wigner-Seitz cell interaction feature, as well as the important collective quantum diffraction of electrons. It is observed that the electron number-density has fundamental effect on the free-free and bound-bound bremsstrahlung radiation spectra over the whole frequency range of radiation. By comparing the radiation spectra for the quantum plasmas with ions of bare Coulomb, Thomas-Fermi, and extended quantum potentials, many important features of the bremsstrahlung radiation is highlighted. Current investigation can provide important information on plasma diagnostics for atomic processes in dense plasmas, such as the inertial-confinement fusion, warm dense matter, and the planetary cores. The results can also help in better understanding of the cooling processes in completely degenerate hot compact stellar objects such as white dwarfs.

  9. Standardization of Procedures for the Preparation of (177)Lu- and (90)Y-labeled DOTA-Rituximab Based on the Freeze-dried Kit Formulation.

    PubMed

    Wojdowska, Wioletta; Karczmarczyk, Urszula; Maurin, Michal; Garnuszek, Piotr; Mikołajczak, Renata

    2015-01-01

    Rituximab when radiolabelled with (177)Lu or (90)Y has been investigated for the treatment of patients with Non-Hodgkin's Lymphoma. In this study, we optimized the preparation of antibody conjugates with chelating agent in the freeze-dried kit. It shortens procedures needed for the successful radiolabeling with lutetium-177 and yttrium-90 and assures reproducible labelling yields. Various molar ratios of Rituximab:DOTA (from 1:5 to 1:100) were used at the conjugation step and different purification method to remove unbound DOTA were investigated (size-exclusion chromatography, dialysis, ultrafiltration). The final monoclonal antibody concentration was quantified by Bradford method, and the number of DOTA molecules was determined by radiolabeling assay using (64)Cu. The specific activity of (177)Lu-DOTA-Rituximab and (90)Y-DOTA-Rituximab were optimized using various amounts of radiometal. Quality control (SE-HPLC, ITLC) and stability study were performed. An average of 4.2 ± 0.8 p-SCN-Bz-DOTA molecules could be randomly conjugated to a single molecule of Rituximab. The ultrafiltration system was the most efficient for purification and resulted in the highest recovery efficiency (77.2%). At optimized conditions the (177)Lu-DOTARituximab and (90)Y-DOTA-Rituximab were obtained with radiochemical purity >99% and specific activity ca. 600 MBq/mg. The radioimmunoconjugates were stable in human serum and 0.9% NaCl. After 72 h of incubation the radiochemical purity of (177)Lu-DOTA-Rituximab decreased to 94% but it was still more than 88% for (90)Y-DOTA-Rituximab. The radioimmunoconjugate showed stability after six months storage at 2 - 8(0)C, as a lyophilized formulation. Our study shows that Rituximab-DOTA can be efficiently radiolabeled with (177)Lu and (90)Y via p-SCN-Bn-DOTA using a freezedried kit.

  10. The AdaptiSPECT Imaging Aperture

    PubMed Central

    Chaix, Cécile; Moore, Jared W.; Van Holen, Roel; Barrett, Harrison H.; Furenlid, Lars R.

    2015-01-01

    In this paper, we present the imaging aperture of an adaptive SPECT imaging system being developed at the Center for Gamma Ray Imaging (AdaptiSPECT). AdaptiSPECT is designed to automatically change its configuration in response to preliminary data, in order to improve image quality for a particular task. In a traditional pinhole SPECT imaging system, the characteristics (magnification, resolution, field of view) are set by the geometry of the system, and any modification can be accomplished only by manually changing the collimator and the distance of the detector to the center of the field of view. Optimization of the imaging system for a specific task on a specific individual is therefore difficult. In an adaptive SPECT imaging system, on the other hand, the configuration can be conveniently changed under computer control. A key component of an adaptive SPECT system is its aperture. In this paper, we present the design, specifications, and fabrication of the adaptive pinhole aperture that will be used for AdaptiSPECT, as well as the controls that enable autonomous adaptation. PMID:27019577

  11. SPECT in the diagnosis of hepatic hemangioma

    SciTech Connect

    Brunetti, J.C.; Van Heertum, R.L.; Yudd, A.P.

    1985-05-01

    Tc99m labeled red blood cell blood flow and delayed static blood pool imaging is widely accepted as a reliable, accurate method for the diagnosis of hepatic hemangiomata. The purpose of this study is to assess the relative value of SPECT blood pool imaging in the evaluation of hepatic hemangionata. A total of 68 patients, including 21 patients with proven hepatic cavernous hemangiomas, were studied using both planar and SPECT imaging techniques. All patients underwent multi-phase evaluation which included a hepatic flow study, immediate planar images of the liver, followed by a 360/sup 0/ tomographic (SPECT) study and subsequent 60 minute delayed static planar hepatic blood pool images. All 21 patients with proven hepatic hemangiomas had a positive SPECT exam and 17 of the 21 (81%) patients had a positive planar exam. In the 21 patients, there were a total of 36 hemangiomas ranging in size from .7 cm to 13 cm. The SPECT imaging technique correctly identified all 36 lesions (100%) where as planar imaging detected 25 of the 36 lesions (69.4%). In all the remaining patients (10-normal, 17-metastatic disease, 12-hepatocellular disease, 6-hepatoma, 2-liver cysts), both the planar and SPECT imaging techniques were interpreted as showing no evidence of focal sequestration of red blood cells. SPECT hepatic blood pool imaging represents an improvement in the evaluation of hepatic hemangioma as a result of a reduction in imaging time (less than thirty minutes), improved spatial resolution and greater overall accuracy.

  12. Integration of AdaptiSPECT, a small-animal adaptive SPECT imaging system

    PubMed Central

    Chaix, Cécile; Kovalsky, Stephen; Kosmider, Matthew; Barrett, Harrison H.; Furenlid, Lars R.

    2015-01-01

    AdaptiSPECT is a pre-clinical adaptive SPECT imaging system under final development at the Center for Gamma-ray Imaging. The system incorporates multiple adaptive features: an adaptive aperture, 16 detectors mounted on translational stages, and the ability to switch between a non-multiplexed and a multiplexed imaging configuration. In this paper, we review the design of AdaptiSPECT and its adaptive features. We then describe the on-going integration of the imaging system. PMID:26347197

  13. SPECT Imaging: Basics and New Trends

    NASA Astrophysics Data System (ADS)

    Hutton, Brian F.

    Single Photon Emission Computed Tomography (SPECT) is widely used as a means of imaging the distribution of administered radiotracers that have single-photon emission. The most widely used SPECT systems are based on the Anger gamma camera, usually involving dual detectors that rotate around the patient. Several factors affect the quality of SPECT images (e.g., resolution and noise) and the ability to perform absolute quantification (e.g., attenuation, scatter, motion, and resolution). There is a trend to introduce dual-modality systems and organ-specific systems, both developments that enhance diagnostic capability.

  14. Awake animal SPECT: Overview and initial results

    SciTech Connect

    Weisenberger, A G; Majewski, S; McKisson, J; Popov, V; Proffitt, J; Stolin, A; Baba, J S; Goddard, J S; Lee, S J; Smith, M F; Tsui, B; Pomper, M

    2009-02-01

    A SPECT / X-ray CT system configured at Johns Hopkins University to image the biodistribution of radiopharmaceuticals in unrestrained, un-anesthetized mice has been constructed and tested on awake mice. The system was built by Thomas Jefferson National Accelerator Facility and Oak Ridge National Laboratory. SPECT imaging is accomplished using two gamma cameras, 10 cm × 20 cm in size based on a 2 × 4 array of Hamamatsu H8500 flat panel position sensitive photomultiplier tubes. A real-time optical tracking system utilizing three infrared cameras provides time stamped pose data of an awake mouse head during a SPECT scan. The six degrees of freedom (three translational and three rotational) pose data are used for motion correction during 3-D tomographic list-mode iterative image reconstruction. SPECT reconstruction of awake, unrestrained mice with motion compensation for head movement has been accomplished.

  15. ADAPTIVE SMALL-ANIMAL SPECT/CT

    PubMed Central

    Furenlid, L.R.; Moore, J.W.; Freed, M.; Kupinski, M.A.; Clarkson, E.; Liu, Z.; Wilson, D.W.; Woolfenden, J.M.; Barrett, H.H.

    2015-01-01

    We are exploring the concept of adaptive multimodality imaging, a form of non-linear optimization where the imaging configuration is automatically adjusted in response to the object. Preliminary studies suggest that substantial improvement in objective, task-based measures of image quality can result. We describe here our work to add motorized adjustment capabilities and a matching CT to our existing FastSPECT II system to form an adaptive small-animal SPECT/CT. PMID:26617457

  16. Cerebral SPECT imaging: Impact on clinical management

    SciTech Connect

    Bloom, M.; Jacobs, S.; Pozniakof, T.

    1994-05-01

    Although cerebral SPECT has been reported to be of value in a variety of neurologic disorders, there is limited data available on the value of SPECT relative to clinical management decisions. The purpose of this study was to determine the effect of cerebral SPECT imaging on patient management. A total of 94 consecutive patients referred for clinical evaluation with brain SPECT were included in this study. Patients were assigned to one of nine groups depending on the clinical indication for the study. These groups included transient ischemia (16), stroke (20), dementia (18), seizures (5), hemorrhage (13), head trauma (6), arteriovenous malformations (6), encephalopathy (6) and a miscellaneous (4) group. All patients were injected with 99mTc HMPAO in doses ranging from 15 mCi to 22 mCi (555 MBq to 814 MBq) and scanned on a triple headed SPECT gamma camera. Two weeks after completion of the study, a standardized interview was conducted between the nuclear and referring physicians to determine if the SPECT findings contributed to an alteration in patient management. Overall, patient management was significantly altered in 47% of the cases referred. The greatest impact on patient management occurred in the group evaluated for transient ischemia, where a total of 13/16 (81%) of patients had their clinical management altered as a result of the cerebral SPECT findings. Clinical management was altered in 61% of patients referred for evaluation of dementia, 67% of patients evaluated for arteriovenous malformations, and 50% of patients with head trauma. In the remainder of the patients, alteration in clinical management ranged from 17% to 50% of patients. This study demonstrates the clinical utility of cerebral SPECT imaging since in a significant number of cases clinical management was altered as a result of the examination. Long term follow up will be necessary to determine patient outcome.

  17. Internal bremsstrahlung signatures in light of direct dark matter searches

    SciTech Connect

    Garny, Mathias; Ibarra, Alejandro; Pato, Miguel; Vogl, Stefan E-mail: ibarra@tum.de E-mail: stefan.vogl@tum.de

    2013-12-01

    Although proposed long ago, the search for internal bremsstrahlung signatures has only recently been made possible by the excellent energy resolution of ground-based and satellite-borne gamma-ray instruments. Here, we investigate thoroughly the current status of internal bremsstrahlung searches in light of the results of direct dark matter searches and in the framework of a minimal mass-degenerate scenario consisting of a Majorana dark matter particle that couples to a fermion and a scalar via a Yukawa coupling. The upper limits on the annihilation cross section set by Fermi-LAT and H.E.S.S. extend uninterrupted from tens of GeV up to tens of TeV and are rather insensitive to the mass degeneracy in the particle physics model. In contrast, direct searches are best in the moderate to low mass splitting regime, where XENON100 limits overshadow Fermi-LAT and H.E.S.S. up to TeV masses if dark matter couples to one of the light quarks. In our minimal scenario we examine carefully the prospects for GAMMA-400, CTA and XENON1T, all planned to come online in the near future, and find that: (a) CTA and XENON1T are fully complementary, with CTA most sensitive to multi-TeV masses and mass splittings around 10%, and XENON1T probing best small mass splittings up to TeV masses; and (b) current constraints from XENON100 already preclude the observation of any spectral feature with GAMMA-400 in spite of its impressive energy resolution, unless dark matter does not couple predominantly to light quarks. Finally, we point out that, unlike for direct searches, the possibility of detecting thermal relics in upcoming internal bremsstrahlung searches requires, depending on the concrete scenario, boost factors larger than 5–10.

  18. Internal bremsstrahlung signatures in light of direct dark matter searches

    NASA Astrophysics Data System (ADS)

    Garny, Mathias; Ibarra, Alejandro; Pato, Miguel; Vogl, Stefan

    2013-12-01

    Although proposed long ago, the search for internal bremsstrahlung signatures has only recently been made possible by the excellent energy resolution of ground-based and satellite-borne gamma-ray instruments. Here, we investigate thoroughly the current status of internal bremsstrahlung searches in light of the results of direct dark matter searches and in the framework of a minimal mass-degenerate scenario consisting of a Majorana dark matter particle that couples to a fermion and a scalar via a Yukawa coupling. The upper limits on the annihilation cross section set by Fermi-LAT and H.E.S.S. extend uninterrupted from tens of GeV up to tens of TeV and are rather insensitive to the mass degeneracy in the particle physics model. In contrast, direct searches are best in the moderate to low mass splitting regime, where XENON100 limits overshadow Fermi-LAT and H.E.S.S. up to TeV masses if dark matter couples to one of the light quarks. In our minimal scenario we examine carefully the prospects for GAMMA-400, CTA and XENON1T, all planned to come online in the near future, and find that: (a) CTA and XENON1T are fully complementary, with CTA most sensitive to multi-TeV masses and mass splittings around 10%, and XENON1T probing best small mass splittings up to TeV masses; and (b) current constraints from XENON100 already preclude the observation of any spectral feature with GAMMA-400 in spite of its impressive energy resolution, unless dark matter does not couple predominantly to light quarks. Finally, we point out that, unlike for direct searches, the possibility of detecting thermal relics in upcoming internal bremsstrahlung searches requires, depending on the concrete scenario, boost factors larger than 5-10.

  19. Secondary-electron-bremsstrahlung imaging for proton therapy

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Mitsutaka; Nagao, Yuto; Ando, Koki; Yamamoto, Seiichi; Toshito, Toshiyuki; Kataoka, Jun; Kawachi, Naoki

    2016-10-01

    A feasibility study on an imaging technique of a therapeutic proton-beam trajectory using a gamma camera by measuring secondary electron bremsstrahlung (SEB) was performed by means of Monte Carlo simulations and a beam-irradiation experiment. From the simulation and experimental results, it was found that a significant amount of SEB yield exists between the beam-injection surface and the range position along the beam axis and the beam trajectory is clearly imaged by the SEB yield. It is concluded that the SEB imaging is a promising technique for monitoring of therapeutic proton-beam trajectories.

  20. Transplanckian Gravitational Bremsstrahlung in Post-Linear Formalism

    NASA Astrophysics Data System (ADS)

    Gal'tsov, Dmitry; Spirin, Pavel

    2015-01-01

    We report on calculation of classical ultrarelativistic gravitational bremsstrahlung in particle collisions in the ADD model with d toroidal extra dimensions using post-linear approximation. The radiation efficiency γ ≡ Erad/Einitial obtained can be expressed in terms of the Schwarzschild radius rS corresponding to the collision energy √ s, the impact parameter b and the center-of-mass Lorentz factor γcm as follows: ɛ = C_d ( {r_S /b} )^{3d + 3} × γ _{cm}^ν with some d-dependent power ν. This is larger than previously known estimates and is interpreted as indication on string radiative damping of transplanckian collisions.

  1. Brain SPECT quantitation in clinical diagnosis

    SciTech Connect

    Hellman, R.S.

    1991-12-31

    Methods to quantitate SPECT data for clinical diagnosis should be chosen so that they take advantage of the lessons learned from PET data. This is particularly important because current SPECT high-resolution brain imaging systems now produce images that are similar in resolution to those generated by the last generation PET equipment (9 mm FWHM). These high-resolution SPECT systems make quantitation of SPECT more problematic than earlier. Methodology validated on low-resolution SPECT systems may no longer be valid for data obtained with the newer SPECT systems. For example, in patients with dementia, the ratio of parietal to cerebellar activity often was studied. However, with new instruments, the cerebellum appears very different: discrete regions are more apparent. The large cerebellar regions usually used with older instrumentation are of an inappropriate size for the new equipment. The normal range for any method of quantitation determined using older equipment probably changes for data obtained with new equipment. It is not surprising that Kim et al. in their simulations demonstrated that because of the finite resolution of imaging systems, the ability to measure pure function is limited, with {open_quotes}anatomy{close_quotes} and {open_quotes}function{close_quotes} coupled in a {open_quotes}complex nonlinear way{close_quotes}. 11 refs.

  2. Absorbed dose assessment of cardiac and other tissues around the cardiovascular system in brachytherapy with 90Sr/90Y source by Monte Carlo simulation.

    PubMed

    Saghamanesh, S; Karimian, A; Abdi, M

    2011-09-01

    Cardiac disease is one of the most important causes of death in the world. Coronary artery stenosis is a very common cardiac disease. Intravascular brachytherapy (IVBT) is one of the radiotherapy methods which have been used recently in coronary artery radiation therapy for the treatment of restenosis. (90)Sr/(90)Y, a beta-emitting source, is a proper option for cardiovascular brachytherapy. In this research, a Monte Carlo simulation was done to calculate dosimetry parameters and effective equivalent doses to the heart and its surrounding tissues during IVBT. The results of this study were compared with the published experimental data and other simulations performed by different programs but with the same source of radiation. A very good agreement was found between results of this work and the published data. An assessment of the risk for cardiac and other sensitive soft tissues surrounding the treated vessel during (90)Sr/(90)Y IVBT was also performed in the study.

  3. Genotoxic and cytotoxic effects of 60Co gamma-rays and 90Sr/90Y beta-rays on Chinese hamster ovary cells (CHO-K1).

    PubMed

    Murakami, Daniella; Suzuki, Miriam Fussae; da Silva Dias, Mauro; Okazaki, Kayo

    2004-07-01

    Among various types of ionizing radiation, the beta emitter radionuclides are involved in many sectors of human activity, such as nuclear medicine, nuclear industries and biomedicine, with a consequently increased risk of accidental, occupational or therapeutic exposure. Despite their recognized importance, there is little information about the effect of beta particles at the cellular level when compared to other types of ionizing radiation. Thus, the objective of the present study was to evaluate the genotoxic and cytotoxic effects of (90)Sr/(90)Y-a pure, highly energetic beta source-on Chinese hamster ovary (CHO) cells and to compare them with data obtained with (60)Co. CHO cells irradiated with different doses of (60)Co (0.34 Gy min(-1)) and (90)Sr/(90)Y (0.23 Gy min(-1)) were processed for analysis of clonogenic death, induction of micronuclei (MN) and interphase death. The survival curves obtained for both types of radiation were fitted by the exponential quadratic model and were found to be similar. Also, the cytogenetic results showed similar frequencies of radio-induced MN between gamma and beta radiations and the MN distribution pattern among cells did not follow the expected Poisson probability pattern. The relative variance values were significantly higher in cells irradiated with (90)Sr/(90)Y than with (60)Co in all exposure doses. The irradiated cells showed more necrotic cells 72 h and 96 h after exposure to beta than to gamma radiation. In general, the (90)Sr/(90)Y beta-radiation was more damaging than (60)Co gamma-rays. The data obtained also demonstrated the need to use several parameters for a better estimate of cellular sensitivity to the action of genotoxic agents, which would be important in terms of radiobiology, oncology and therapeutics.

  4. Molecular bremsstrahlung radiation at GHz frequencies in air

    NASA Astrophysics Data System (ADS)

    Al Samarai, Imen; Bérat, Corinne; Deligny, Olivier; Letessier-Selvon, Antoine; Montanet, François; Settimo, Mariangela; Stassi, Patrick

    2016-03-01

    A detection technique for ultra-high-energy cosmic rays, complementary to the fluorescence technique, would be the use of the molecular bremsstrahlung radiation emitted by low-energy ionization electrons left after the passage of the showers in the atmosphere. In this article, a detailed estimate of the spectral intensity of photons at ground level originating from this radiation is presented. The spectral intensity expected from the passage of the high-energy electrons of the cascade is also estimated. The absorption of the photons in the plasma of electrons and neutral molecules is shown to be negligible. The obtained spectral intensity is shown to be 2 ×1 0-21 W cm-2 GHz-1 at 10 km from the shower core for a vertical shower induced by a proton of 1 017.5 eV . In addition, a recent measurement of bremsstrahlung radiation in air at gigahertz frequencies from a beam of electrons produced at 95 keV by an electron gun is also discussed and reasonably reproduced by the model.

  5. Scalar dark matter models with significant internal bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Giacchino, Federica; Lopez-Honorez, Laura; Tytgat, Michel H. G.

    2013-10-01

    There has been interest recently on particle physics models that may give rise to sharp gamma ray spectral features from dark matter annihilation. Because dark matter is supposed to be electrically neutral, it is challenging to build weakly interacting massive particle models that may accommodate both a large cross section into gamma rays at, say, the Galactic center, and the right dark matter abundance. In this work, we consider the gamma ray signatures of a class of scalar dark matter models that interact with Standard Model dominantly through heavy vector-like fermions (the vector-like portal). We focus on a real scalar singlet S annihilating into lepton-antilepton pairs. Because this two-body final-state annihilation channel is d-wave suppressed in the chiral limit, σfbar fvproptov4, we show that virtual internal bremsstrahlung emission of a gamma ray gives a large correction, both today and at the time of freeze-out. For the sake of comparison, we confront this scenario to the familiar case of a Majorana singlet annihilating into light lepton-antilepton pairs, and show that the virtual internal bremsstrahlung signal may be enhanced by a factor of (up to) two orders of magnitude. We discuss the scope and possible generalizations of the model.

  6. Experimental Time Resolved Electron Beam Temperature Measurements Using Bremsstrahlung Diagnostics

    SciTech Connect

    Menge, P.R.; Maenchen, J.E.; Mazarakis, M.G.; Rosenthal, S.E.

    1999-06-25

    Electron beam temperature, {beta}{perpendicular} (= v{perpendicular}/v), is important to control for the development of high dose flash radiographic bremsstrahlung sources. At high voltage (> 5 MV) increasing electron beam temperature has a serious deleterious effect on dose production. The average and time resolved behavior of beam temperature was measured during radiographic experiments on the HERMES III accelerator (10 MV, 50 kA, 70 ns). A linear array of thermoluminescent dosimeters (TLDs) were used to estimate the time integrated average of beam temperature. On and off-axis photoconducting diamond (PCD) detectors were used to measure the time resolved bremsstrahlung dose rate, which is dependent on beam energy and temperature. The beam temperature can be determined by correlating PCD response with accelerator voltage and current and also by analyzing the ratio of PCD amplitudes on and off axis. This ratio is insensitive to voltage and current and thus, is more reliable than utilizing absolute dose rate. The data is unfolded using comparisons with Monte Carlo simulations to obtain absolute beam temperatures. The data taken on HERMES III show abrupt increases in {beta}{perpendicular} midway through the pulse indicating rapid onset of beam instability.

  7. An Investigation of Bremsstrahlung Reflection in a Dense Plasma Focus (DPF) Propulsion Device

    DTIC Science & Technology

    2006-01-01

    performed on laser -driven fusion radiation cavities, multilayer reflectors, and their application to Bremsstrahlung radiation reflection is presented...search has been performed on laser -driven fusion radiation cavities, multilayer reflectors, and their application to Bremsstrahlung radiation...reemission of the photons. Both cases will be presented here, beginning with an estimation of the flux, temperature, and ablation at the wall using classical

  8. Quasiclassical description of bremsstrahlung accompanying {alpha} decay including quadrupole radiation

    SciTech Connect

    Jentschura, U. D.; Milstein, A. I.; Terekhov, I. S.; Boie, H.; Scheit, H.; Schwalm, D.

    2008-01-15

    We present a quasiclassical theory of {alpha} decay accompanied by bremsstrahlung with a special emphasis on the case of {sup 210}Po, with the aim of finding a unified description that incorporates both the radiation during the tunneling through the Coulomb wall and the finite energy E{sub {gamma}} of the radiated photon up to E{sub {gamma}}{approx}Q{sub {alpha}}/{radical}({eta}), where Q{sub {alpha}} is the {alpha}-decay Q-value and {eta} is the Sommerfeld parameter. The corrections with respect to previous quasiclassical investigations are found to be substantial, and excellent agreement with a full quantum mechanical treatment is achieved. Furthermore, we find that a dipole-quadrupole interference significantly changes the {alpha}-{gamma} angular correlation. We obtain good agreement between our theoretical predictions and experimental results.

  9. Spectra and rates of bremsstrahlung neutrino emission in stars

    NASA Astrophysics Data System (ADS)

    Guo, Gang; Qian, Yong-Zhong

    2016-08-01

    We calculate the energy-differential rate for neutrino emission from electron-nucleus bremsstrahlung in stellar interiors taking into account the effects of electron screening and ionic correlations. We compare the energy-differential and the net rates, as well as the average ν¯e and ν¯x(x =μ ,τ ) energies, for this process with those for e± pair annihilation, plasmon decay, and photoneutrino emission over a wide range of temperature and density. We also compare our updated energy loss rates for the above thermal neutrino emission processes with the fitting formulas widely used in stellar evolution models and determine the temperature and density domain in which each process dominates. We discuss the implications of our results for detection of ν¯e from massive stars during their presupernova evolution and find that pair annihilation makes the predominant contribution to the signal from the thermal emission processes.

  10. Internal bremsstrahlung of β decay of atomic S3516

    NASA Astrophysics Data System (ADS)

    Ivanov, A. N.; Höllwieser, R.; Wellenzohn, M.; Troitskaya, N. I.; Berdnikov, Ya. A.

    2014-12-01

    We calculate the energy spectra and the branching ratio of the internal bremsstrahlung (IB) of the β- decay of atomic S3516 . We show that the theoretical spectrum of the IB, calculated within the standard model and QED, fits well the experimental spectra, measured by M. S. Powar and M. Singh [J. Phys. G: Nucl. Part. Phys. 2, 43 (1976), 10.1088/0305-4616/2/1/006] and by A. Singh and A. S. Dhaliwal [Appl. Radiat. Isot. 94, 44 (2014), 10.1016/j.apradiso.2014.07.003] for the photon energy regions 0.025 ≤ω ≤0.150 MeV and 0.001 ≤ω ≤0.100 MeV , respectively.

  11. Neutrino-pair bremsstrahlung from nucleon-nucleon scattering

    DOE PAGES

    Li, Yi; Liou, M. K.; Schreiber, W. M.; ...

    2015-07-22

    Background: Neutrino-pair bremsstrahlung processes from nucleon-nucleon scattering ΝΝνν¯ (nnvv¯, ppvv¯, and npvv¯) have recently attracted attention in studies of neutrino emission in neutron stars, because of the implications for the neutron star cooling. The calculated ΝΝνν¯ emissivities within the neutron star environment are relatively insensitive to the two-nucleon dynamical model used in the calculations, but differ significantly from those obtained using an OPE model. Purpose: To investigate the free ΝΝνν¯ cross sections using a realistic nucleon-nucleon scattering amplitude, comparing the relative sizes of the cross sections for the three processes nnvv¯, ppvv¯, and npvv¯.

  12. Laser radiography forming bremsstrahlung radiation to image an object

    DOEpatents

    Perry, Michael D.; Sefcik, Joseph A.

    2004-01-13

    A method of imaging an object by generating laser pulses with a short-pulse, high-power laser. When the laser pulse strikes a conductive target, bremsstrahlung radiation is generated such that hard ballistic high-energy electrons are formed to penetrate an object. A detector on the opposite side of the object detects these electrons. Since laser pulses are used to form the hard x-rays, multiple pulses can be used to image an object in motion, such as an exploding or compressing object, by using time gated detectors. Furthermore, the laser pulses can be directed down different tubes using mirrors and filters so that each laser pulse will image a different portion of the object.

  13. Neutrino-pair bremsstrahlung from nucleon-nucleon scattering

    NASA Astrophysics Data System (ADS)

    Li, Yi; Liou, M. K.; Schreiber, W. M.; Gibson, B. F.

    2015-07-01

    Background: Neutrino-pair bremsstrahlung processes from nucleon-nucleon scattering N N ν ν ¯ (n n ν ν ¯ ,p p ν ν ¯ , and n p ν ν ¯ ) have recently attracted attention in studies of neutrino emission in neutron stars, because of the implications for the neutron star cooling. The calculated N N ν ν ¯ emissivities within the neutron star environment are relatively insensitive to the two-nucleon dynamical model used in the calculations, but differ significantly from those obtained using an one-pion-exchange (OPE) model. Purpose: We investigate the free N N ν ν ¯ cross sections using a realistic nucleon-nucleon scattering amplitude, comparing the relative sizes of the cross sections for the three processes n n ν ν ¯ ,p p ν ν ¯ , and n p ν ν ¯ . Method: We employ a realistic one-boson-exchange (ROBE) model for N N scattering and combine those strong scattering amplitudes with the well-known nucleon weak interaction vertices to construct weak bremsstrahlung amplitudes. Using the resulting N N ν ν ¯ amplitudes we investigate the relative importance of the vector (ΓVμ) , axial vector (ΓAμ) , and tensor (ΓTμ) terms. The ROBE model bremsstrahlung amplitudes are also used as a two-nucleon dynamical model with which we calculate the cross sections d/σ d ω for n n ν ν ¯ ,p p ν ν ¯ , and n p ν ν ¯ . Results: The three free N N ν ν ¯ cross sections d/σ d ω are of similar order of magnitude. Each increases with increasing neutrino-pair energy ω . For the neutrino-pair energy of ω =1 MeV our n n ν ν ¯ results are in quantitative agreement with those previously reported by Timmermans et al. [Phys. Rev. C 65, 064007 (2002), 10.1103/PhysRevC.65.064007], who used the leading-order term of the soft-neutrino-pair bremsstrahlung amplitude to calculate the cross sections. Differences between the n n ν ν ¯ and p p ν ν ¯ cross section are not discernible over the nucleon-nucleon incident energy region considered, due to the

  14. Inverse bremsstrahlung heating rate for dense plasmas in laser fields

    NASA Astrophysics Data System (ADS)

    Dey, R.; Roy, A. C.

    2013-07-01

    We report a theoretical analysis of inverse bremsstrahlung heating rate in the eikonal approximation. The present analysis is performed for a dense plasma using the screened electron-ion interaction potential for the ion charge state Zi = 1 and for both the weak and strong plasma screening cases. We have also compared the eikonal results with the first Born approximation (FBA) [M. Moll et al., New J. Phys. 14, 065010 (2012)] calculation. We find that the magnitudes of inverse bremsstrahlung heating rate within the eikonal approximation (EA) are larger than the FBA values in the weak screening case (κ = 0.03 a.u.) in a wide range of field strength for three different initial electron momenta (2, 3, and 4 a.u.). But for strong screening case (κ = 0.3 a.u.), the heating rates predicted by the two approximations do not differ much after reaching their maximum values. Furthermore, the individual contribution of photoemission and photoabsorption processes to heating rate is analysed for both the weak and strong screening cases. We find that the single photoemission and photoabsorption rates are the same throughout the field strength while the multiphoton absorption process dominates over the multiphoton emission process beyond the field strength ≈ 4×108 V/cm. The present study of the dependence of heating rate on the screening parameter ranging from 0.01 to 20 shows that whereas the heating rate predicted by the EA is greater than the FBA up to the screening parameter κ = 0.3 a.u., the two approximation methods yield results which are nearly identical beyond the above value.

  15. Inverse bremsstrahlung heating rate for dense plasmas in laser fields

    SciTech Connect

    Dey, R.; Roy, A. C.

    2013-07-15

    We report a theoretical analysis of inverse bremsstrahlung heating rate in the eikonal approximation. The present analysis is performed for a dense plasma using the screened electron-ion interaction potential for the ion charge state Z{sub i} = 1 and for both the weak and strong plasma screening cases. We have also compared the eikonal results with the first Born approximation (FBA) [M. Moll et al., New J. Phys. 14, 065010 (2012)] calculation. We find that the magnitudes of inverse bremsstrahlung heating rate within the eikonal approximation (EA) are larger than the FBA values in the weak screening case (κ = 0.03 a.u.) in a wide range of field strength for three different initial electron momenta (2, 3, and 4 a.u.). But for strong screening case (κ = 0.3 a.u.), the heating rates predicted by the two approximations do not differ much after reaching their maximum values. Furthermore, the individual contribution of photoemission and photoabsorption processes to heating rate is analysed for both the weak and strong screening cases. We find that the single photoemission and photoabsorption rates are the same throughout the field strength while the multiphoton absorption process dominates over the multiphoton emission process beyond the field strength ≈ 4×10{sup 8} V/cm. The present study of the dependence of heating rate on the screening parameter ranging from 0.01 to 20 shows that whereas the heating rate predicted by the EA is greater than the FBA up to the screening parameter κ = 0.3 a.u., the two approximation methods yield results which are nearly identical beyond the above value.

  16. Neutrino-antineutrino pair production by hadronic bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Bacca, Sonia

    2016-09-01

    I will report on recent calculations of neutrino-antineutrino pair production from bremsstrahlung processes in hadronic collisions and consider temperature conditions relevant for core collapse supernovae. Earlier studies on bremsstrahlung from neutron-neutron collisions showed that the approximation used in typical supernova simulation to model this process differs by about a factor of 2 from predictions based on chiral effective field theory, where the chiral expansion of two-body forces is considered up to the next-to-next-to-next-to-leading order. When the density of neutrons is large enough this process may compete with other non-hadronic reactions in the production of neutrinos, in particular in the case of μ and τ neutrinos, which are not generated by charged-current reactions. A natural question to ask is then: what is the effect of neutrino pair production from collisions of neutrons with finite nuclei? To tackle this question, we recently have addressed the case of neutron- α collisions, given that in the P-wave channels the neutron- α scattering features a resonance near 1 MeV. We find that the resonance leads to an enhanced contribution in the neutron spin structure function at temperatures in the range of 0 . 1 - 4 MeV. For significant density fractions of α in this temperature range, this process is competitive with contributions from neutron-neutron scattering. TRIUMF receives federal funding via a contribution agreement with the National Research Council of Canada. This work was supported in parts by the Natural Sciences and Engineering Research Council (Grant Number SAPIN-2015-0003).

  17. Evaluation of beta-absorbed fractions in a mouse model for 90Y, 188Re, 166Ho, 149Pm, 64Cu, and 177Lu radionuclides.

    PubMed

    Miller, William H; Hartmann-Siantar, Christine; Fisher, Darrell; Descalle, Marie-Anne; Daly, Tom; Lehmann, Joerg; Lewis, Michael R; Hoffman, Timothy; Smith, Jeff; Situ, Peter D; Volkert, Wynn A

    2005-08-01

    Several short-lived, high-energy beta emitters are being proposed as the radionuclide components for molecular- targeted potential cancer therapeutic agents. The laboratory mice used to determine the efficacy of these new agents have organs that are relatively small compared to the ranges of these high-energy particles. The dosimetry model developed by Hui et al. was extended to provide realistic beta-dose estimates for organs in mice that received therapeutic radiopharmaceuticals containing (90)Y, (188)Re, (166)Ho, (149)Pm, (64)Cu, and (177)Lu. Major organs in this model included the liver, spleen, kidneys, lungs, heart, stomach, small and large bowel, thyroid, pancreas, bone, marrow, carcass, and a 0.025-g tumor. The study as reported in this paper verifies their results for (90)Y and extends them by using their organ geometry factors combined with newly calculated organ self-absorbed fractions from PEREGRINE and MCNP. PEREGRINE and MCNP agree to within 8% for the worst-case organ with average differences (averaged over all organs) decreasing from 5% for (90)Y to 1% for (177)Lu. When used with typical biodistribution data, the three different models predict doses that are in agreement to within 5% for the worst-case organ. The beta-absorbed fractions and cross-organ-deposited energy provided in this paper can be used by researchers to predict mouse-organ doses and should contribute to an improved understanding of the relationship between dose and radiation toxicity in mouse models where use of these isotopes is favorable.

  18. Evaluation of Beta-Absorbed Fractions in a Mouse Model for 90Y, 188Re, 166Ho, 149Pm, 64Cu, and 177Lu Radionuclides

    SciTech Connect

    Miller, William H.; Hartmann-Siantar, Christine; Fisher, Darrell R.; Descalle, Marie-Anne; Daly, Tom; Lehmann, Joerg; Lewis, Michael R.; Hoffman, Timothy J.; Smith, Jeff; Situ, Peter D.; Volkert, Wynn A.

    2005-08-01

    Several short-lived, high-energy beta emitters are being proposed as the radionuclide components for molecular-targeted potential cancer therapeutic agents. The laboratory mice used to determine the efficacy of these new agents have organs that are relatively small compared to the ranges of these high-energy particles. The dosimetry model developed by Hui et al. was extended to provide realistic beta-dose estimates for organs in mice that received therapeutic radiopharmaceuticals containing 90Y, 188Re, 166Ho, 149Pm, 64Cu, and 177 Lu. Major organs in this model included the liver, spleen, kidneys, lungs, heart, stomach, small and large bowel, thyroid, pancreas, bone, marrow, carcass, and a 0.025-g tumor. The study as reported in this paper verifies their results for 90Y and extends them by using their organ geometry factors combined with newly calculated organ self-absorbed fractions from PEREGRINE and MCNP. PEREGRINE and MCNP agree to within 8% for the worst-case organ with average differences (averaged over all organs) decreasing from 5% for 90Y to 1% for 177Lu. When used with typical biodistribution data, the three different models predict doses that are in agreement to within 5% for the worst-case organ. The beta-absorbed fractions and cross-organ-deposited energy provided in this paper can be used by researchers to predict mouse-organ doses and should contribute to an improved understanding of the relationship between dose and radiation toxicity in mouse models where use of these isotopes is favorable.

  19. Growth hormone-secreting macroadenoma of the pituitary gland successfully treated with the radiolabeled somatostatin analog (90)Y-DOTATATE: case report.

    PubMed

    Waligórska-Stachura, Joanna; Gut, Paweł; Sawicka-Gutaj, Nadia; Liebert, Włodzimierz; Gryczyńska, Maria; Baszko-Błaszyk, Daria; Blanco-Gangoo, Al Ricardo; Ruchała, Marek

    2016-08-01

    Pituitary tumors causing acromegaly are usually macroadenomas at the time of diagnosis, and they can grow aggressively, infiltrating surrounding tissues. Difficulty in achieving complete tumor removal at surgery can lead toward a strong tendency for recurrence, making it necessary to consider a means of treatment other than those currently used such as somatostatin analogs (SSAs), growth hormone (GH) receptor antagonist, surgical removal, and radiotherapy. The purpose of this paper is to describe a patient diagnosed with an aggressive, giant GH-secreting tumor refractory to medical therapy but ultimately treated with the radiolabeled somatostatin analog (90)Y-DOTATATE. A 26-year-old male with an invasive macroadenoma of the pituitary gland (5.6 × 2.5 × 3.6 cm) and biochemically confirmed acromegaly underwent 2 partial tumor resections: the first used the transsphenoidal approach and the second used the transcranial method. The patient received SSAs pre- and postoperatively. Because of the progression in pituitary tumor size, he underwent classic irradiation of the tumor (50 Gy). One and a half years later, the patient presented with clinically and biochemically active disease, and the tumor size was still 52 mm in diameter (height). Two neurosurgeons disqualified him from further surgical procedures. After confirming the presence of somatostatin receptors in the pituitary tumor by using (68)Ga-DOTATATE PET/CT, we treated the patient 4 times with an SSA bound with (90)Y-DOTATATE. After this treatment, the patient attained partial biochemical remission and a reduction in the tumor mass for the first time. Treatment with an SSA bound with (90)Y-DOTATATE may be a promising option for some aggressive GH-secreting pituitary adenomas when other methods have failed.

  20. Radioembolization with 90Y glass microspheres for the treatment of unresectable metastatic liver disease from chemotherapy-refractory gastrointestinal cancers: final report of a prospective pilot study

    PubMed Central

    Kerlan, Robert K.; Hawkins, Randall A.; Pampaloni, Miguel; Taylor, Andrew G.; Kohi, Maureen P.; Kolli, K. Pallav; Atreya, Chloe E.; Bergsland, Emily K.; Kelley, R. Kate; Ko, Andrew H.; Korn, W. Michael; Van Loon, Katherine; McWhirter, Ryan M.; Luan, Jennifer; Johanson, Curt; Venook, Alan P.

    2016-01-01

    Background This prospective pilot single-institution study was undertaken to document the feasibility, safety, and efficacy of radioembolization of liver-dominant metastatic gastrointestinal cancer using 90Y glass microspheres. Methods Between June 2010 and October 2013, 42 adult patients (26 men, 16 women; median age 60 years) with metastatic chemotherapy-refractory unresectable colorectal (n=21), neuroendocrine (n=11), intrahepatic bile duct (n=7), pancreas (n=2), and esophageal (n=1) carcinomas underwent 60 lobar or segmental administrations of 90Y glass microspheres. Data regarding clinical and laboratory adverse events (AE) were collected prospectively for up to 5.5 years after radioembolization. Radiographic responses were evaluated using Response Evaluation Criteria in Solid Tumors (RECIST), version 1.1. Time to maximum response, response duration, progression-free survival (PFS) (hepatic and extrahepatic), and overall survival (OS) were measured. Results Median target dose and activity were 109.4 Gy and 2.6 GBq per treatment session, respectively. Majority of clinical AE were grade 1 or 2 in severity. Patients with colorectal cancer had hepatic objective response rate (ORR) of 25% and a hepatic disease control rate (DCR) of 80%. Median PFS and OS were 1.0 and 4.4 months, respectively. Patients with neuroendocrine tumors (NET) had hepatic ORR and DCR of 73% and 100%, respectively. Median PFS was 8.9 months for this cohort. DCR and median PFS and OS for patients with cholangiocarcinoma were 86%, 1.1 months, and 6.7 months, respectively. Conclusions 90Y glass microspheres device has a favorable safety profile, and achieved prolonged disease control of hepatic tumor burden in a subset of patients, including all patients enrolled in the neuroendocrine cohort. PMID:28078110

  1. A 90Y-labelled anti-ROBO1 monoclonal antibody exhibits antitumour activity against hepatocellular carcinoma xenografts during ROBO1-targeted radioimmunotherapy

    PubMed Central

    2014-01-01

    Background ROBO1 is a membrane protein that functions in axon guidance. ROBO1 contributes to tumour metastasis and angiogenesis and may have potential as a target protein of immunotherapy because ROBO1 is specifically expressed at high levels in hepatocellular carcinoma. In this study, we examined biodistribution and radioimmunotherapy (RIT) using a radioisotope-labelled anti-ROBO1 monoclonal antibody (MAb) against hepatocellular carcinoma models. Methods ROBO1-positive HepG2 human hepatocellular carcinoma xenograft nude mice were used in this study. We conjugated anti-ROBO1 MAb with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), and the conjugates were labelled with 111In and 90Y. To study biodistribution, the 111In-DOTA-anti-ROBO1 MAb was injected into HepG2 xenograft mice via the tail vein. To evaluate any antitumour effect, a RIT study was performed, and the 90Y-DOTA-anti-ROBO1 MAb was injected via the tail vein. Tumour volume, mouse weight, and blood cell count were periodically measured throughout the experiments. The tumours and organs of mice were collected, and a histopathological analysis was carried out. Results The tumour uptake of 111In-anti-ROBO1 MAb in HepG2 xenograft mice was 15.0% ± 0.69% injected dose per gram at 48 h after injection. Immunotherapy with cold-anti-ROBO1 MAb (70 μg) did not cause a significant antitumour effect. RIT with 6.7 MBq of 90Y-anti-ROBO1 MAb caused significant tumour growth suppression. Transient body weight loss and bone-marrow suppression were observed. Histopathological analyses of tumours revealed the fatal degeneration of tumour cells, significant reduction of the Ki-67 index, and an increase of the apoptosis index. Normal organs showed no significant injury, but a transient reduction of hematopoietic cells was observed in the spleen and in the sternal bone marrow. Conclusions These results suggest that RIT with 90Y-anti-ROBO1 MAb is a promising treatment for ROBO1-positive hepatocellular

  2. A Bremsstrahlung spectrometer using k-edge and differential filters with image plate dosimeters

    SciTech Connect

    Chen, C. D.; Porkolab, M.; King, J. A.; Beg, F. N.; Key, M. H.; Chen, H.; Mackinnon, A. J.; MacPhee, A. G.; Patel, P. K.; Akli, K. U.; Stephens, R. B.; Freeman, R. R.; Link, A.; Van Woerkom, L. D.

    2008-10-15

    A Bremsstrahlung spectrometer using k-edge and differential filtering has been used with image plate dosimeters to measure the x-ray fluence from short-pulse laser/target interactions. An electron spectrometer in front of the Bremsstrahlung spectrometer deflects electrons from the x-ray line of sight and simultaneously measures the electron spectrum. The response functions were modeled with the Monte Carlo code INTEGRATED TIGER SERIES 3.0 and the dosimeters calibrated with radioactive sources. An electron distribution with a slope temperature of 1.3 MeV is inferred from the Bremsstrahlung spectra.

  3. A Bremsstrahlung Spectrometer using k-edge and Differential Filters with Image plate dosimeters

    SciTech Connect

    Chen, C; Mackinnon, A; Beg, F; Chen, H; Key, M; King, J A; Link, A; MacPhee, A; Patel, P; Porkolab, M; Stephens, R; VanWoerkom, L; Akli, K; Freeman, R

    2008-05-02

    A Bremsstrahlung spectrometer using k-edge and differential filtering has been used with Image Plate dosimeters to measure the x-ray fluence from short-pulse laser/target interactions. An electron spectrometer in front of the Bremsstrahlung spectrometer deflects electrons from the x-ray line of sight and simultaneously measures the electron spectrum. The response functions were modeled with the Monte Carlo code Integrated Tiger Series 3.0 and the dosimeters calibrated with radioactive sources. Electron distributions with slope temperatures in the MeV range are inferred from the Bremsstrahlung spectra.

  4. Performance evaluation of D-SPECT: a novel SPECT system for nuclear cardiology

    NASA Astrophysics Data System (ADS)

    Erlandsson, Kjell; Kacperski, Krzysztof; van Gramberg, Dean; Hutton, Brian F.

    2009-05-01

    D-SPECT (Spectrum Dynamics, Israel) is a novel SPECT system for cardiac perfusion studies. Based on CZT detectors, region-centric scanning, high-sensitivity collimators and resolution recovery, it offers potential advantages over conventional systems. A series of measurements were made on a β-version D-SPECT system in order to evaluate its performance in terms of energy resolution, scatter fraction, sensitivity, count rate capability and resolution. Corresponding measurements were also done on a conventional SPECT system (CS) for comparison. The energy resolution of the D-SPECT system at 140 keV was 5.5% (CS: 9.25%), the scatter fraction 30% (CS: 34%), the planar sensitivity 398 s-1 MBq-1 per head (99mTc, 10 cm) (CS: 72 s-1 MBq-1), and the tomographic sensitivity in the heart region was in the range 647-1107 s-1 MBq-1 (CS: 141 s-1 MBq-1). The count rate increased linearly with increasing activity up to 1.44 M s-1. The intrinsic resolution was equal to the pixel size, 2.46 mm (CS: 3.8 mm). The average reconstructed resolution using the standard clinical filter was 12.5 mm (CS: 13.7 mm). The D-SPECT has superior sensitivity to that of a conventional system with similar spatial resolution. It also has excellent energy resolution and count rate characteristics, which should prove useful in dynamic and dual radionuclide studies.

  5. (Depth-dose curves of the beta reference fields (147)Pm, (85)Kr and (90)Sr/(90)Y produced by the beta secondary standard BSS2.

    PubMed

    Brunzendorf, Jens

    2012-08-01

    The most common reference fields in beta dosimetry are the ISO 6980 series 1 radiation fields produced by the beta secondary standard BSS2 and its predecessor BSS. These reference fields require sealed beta radiation sources ((147)Pm, (85)Kr or (90)Sr/(90)Y) in combination with a source-specific beam-flattening filter, and are defined only at a given distance from the source. Every radiation sources shipped with the BSS2 is sold with a calibration certificate of the Physikalisch-Technische Bundesanstalt. The calibration workflow also comprises regular depth-dose measurements. This work publishes complete depth-dose curves of the series 1 sources (147)Pm, (85)Kr and (90)Sr/(90)Y in ICRU tissue up to a depth of 11 mm,when all electrons are stopped. For this purpose, the individual depth-dose curves of all BSS2 sources calibrated so far have been determined, i.e. the complete datasets of all BSS2 beta sources have been re-evaluated. It includes 191 depth-dose curves of 116 different sources comprising more than 2200 data points in total. Appropriate analytical representations of the nuclide-specific depth-dose curves are provided for the first time.

  6. Treatment Parameters and Outcome in 680 Treatments of Internal Radiation With Resin {sup 90}Y-Microspheres for Unresectable Hepatic Tumors

    SciTech Connect

    Kennedy, Andrew S. McNeillie, Patrick M.S.; Dezarn, William A.; Nutting, Charles; Sangro, Bruno; Wertman, Dan; Garafalo, Michael; Liu, David; Coldwell, Douglas; Savin, Michael; Jakobs, Tobias; Rose, Steven; Warner, Richard; Carter, Dennis; Sapareto, Stephen; Nag, Subir; Gulec, Seza; Calkins, Allison; Gates, Vanessa L.; Salem, Riad

    2009-08-01

    Purpose: Radioembolization (RE) using {sup 90}Y-microspheres is an effective and safe treatment for patients with unresectable liver malignancies. Radiation-induced liver disease (RILD) is rare after RE; however, greater understanding of radiation-related factors leading to serious liver toxicity is needed. Methods and Materials: Retrospective review of radiation parameters was performed. All data pertaining to demographics, tumor, radiation, and outcomes were analyzed for significance and dependencies to develop a predictive model for RILD. Toxicity was scored using the National Cancer Institute Common Toxicity Criteria Adverse Events Version 3.0 scale. Results: A total of 515 patients (287 men; 228 women) from 14 US and 2 EU centers underwent 680 separate RE treatments with resin {sup 90}Y-microspheres in 2003-2006. Multifactorial analyses identified factors related to toxicity, including activity (GBq) Selective Internal Radiation Therapy delivered (p < 0.0001), prescribed (GBq) activity (p < 0.0001), percentage of empiric activity (GBq) delivered (p < 0.0001), number of prior liver treatments (p < 0.0008), and medical center (p < 0.0001). The RILD was diagnosed in 28 of 680 treatments (4%), with 21 of 28 cases (75%) from one center, which used the empiric method. Conclusions: There was an association between the empiric method, percentage of calculated activity delivered to the patient, and the most severe toxicity, RILD. A predictive model for RILD is not yet possible given the large variance in these data.

  7. SPECT gallium imaging in abdominal lymphoma

    SciTech Connect

    Adcock, K.A.; Friefeld, G.D.; Waldron, J.A. Jr.

    1986-05-01

    A case of non-Hodgkin's lymphoma of the abdomen studied by gallium SPECT imaging is reported. The tomographic slices accurately demonstrated the location of residual disease after chemotherapy in the region of the transverse mesocolon. Previous transmission CT had shown considerable persistent retroperitoneal lymphadenopathy, but was not helpful in determining the presence of viable lymphoma.

  8. PET and SPECT imaging in veterinary medicine.

    PubMed

    LeBlanc, Amy K; Peremans, Kathelijne

    2014-01-01

    Veterinarians have gained increasing access to positron emission tomography (PET and PET/CT) imaging facilities, allowing them to use this powerful molecular imaging technique for clinical and research applications. SPECT is currently being used more in Europe than in the United States and has been shown to be useful in veterinary oncology and in the evaluation of orthopedic diseases. SPECT brain perfusion and receptor imaging is used to investigate behavioral disorders in animals that have interesting similarities to human psychiatric disorders. This article provides an overview of the potential applications of PET and SPECT. The use of commercially available and investigational PET radiopharmaceuticals in the management of veterinary disease has been discussed. To date, most of the work in this field has utilized the commercially available PET tracer, (18)F-fluorodeoxyglucose for oncologic imaging. Normal biodistribution studies in several companion animal species (cats, dogs, and birds) have been published to assist in lesion detection and interpretation for veterinary radiologists and clinicians. Studies evaluating other (18)F-labeled tracers for research applications are underway at several institutions and companion animal models of human diseases are being increasingly recognized for their value in biomarker and therapy development. Although PET and SPECT technologies are in their infancy for clinical veterinary medicine, increasing access to and interest in these applications and other molecular imaging techniques has led to a greater knowledge and collective body of expertise for veterinarians worldwide. Initiation and fostering of physician-veterinarian collaborations are key components to the forward movement of this field.

  9. Applicability study on existing dosimetry systems to high-power Bremsstrahlung irradiation

    NASA Astrophysics Data System (ADS)

    Mehta, Kishor; Kojima, Takuji; Sunaga, Hiromi

    2003-12-01

    Applicability of the existing dosimetry systems to high-power Bremsstrahlung irradiation was investigated through a dose intercomparison study, where several dosimeters were irradiated in the dose range 4-12 kGy in identical polyethylene phantoms in a Bremsstrahlung beam obtained from a 5-MeV electron accelerator. Included in the study were alanine dosimeters molded by three different binders, three types of liquid dosimeters—ceric-cerous, dichromate and ethanol-chlorobenzen (ECB), and glutamine powder. The dosimeter responses for Bremsstrahlung radiation were analyzed at the issuing laboratories, and the dose values determined using calibration based on cobalt-60 gamma-ray irradiation. Dose values for all the three dose levels for all dosimetry systems were in good agreement—better than 3%. The results of the study demonstrate that these existing dosimetry systems have a potential for application to high-power Bremsstrahlung irradiation.

  10. Electron Bremsstrahlung Cross Sections at 25 and 50 keV from Xe and Kr

    NASA Astrophysics Data System (ADS)

    Portillo, Salvador; Quarles, C. A.

    2002-05-01

    Absolute doubly differential bremsstrahlung cross sections for radiation at 90 from 25 and 50 keV electron bombardment of Kr and Xe of will be presented. The electrons were accelerated by a Cockcroft - Walton accelerator into an Al chamber through a .06" Al collimator. Thick target bremsstrahlung background was minimized by having Al nipples and fixtures and by the addition of a carbon lined nipple placed at 180 to the SiLi detector. A comparison of the doubly differential cross sections will be made with current bremsstrahlung theories. The ratio of the Kr and Xe cross sections will also be compared with the theoretical cross section ratios. The ratio provides a more sensitive test of the contribution, if any, of polarization bremsstrahlung.

  11. Experimental verification of bremsstrahlung production and dosimetry predictions for 15. 5 MeV electrons

    SciTech Connect

    Sanford, T.W.L.; Beutler, D.E.; Halbleib, J.A. ); Knott, D.P. )

    1991-11-01

    The radiation produced by a 15.5-Mev mono-energetic electron beam incident on optimized and non-optimized bremsstrahlung targets is characterized using the ITS Monte Carlo code and measurements with equilibrated and non-equilibrated TLD dosimetry. Comparisons between calculations and measurements verify the calculations and demonstrate that the code can be used to predict both bremsstrahlung production and TLD response for radiation fields that are characteristic of those produced by pulsed simulators of gamma rays. At optimum bremsstrahlung production, the predicted total forward radiation fluence detected in equilibrated TLD dosimetry agrees with that measured within the {plus minus}6% uncertainty of the measurement. The absolute comparisons made here provide independent confirmation of the validity of the TLD calibration for photon fields characteristic of gamma-ray simulators. The empirical Martin equation, which is often used to calculate radiation dose from optimized bremsstrahlung targets, is examined, and its range of validity is established from the data presented.

  12. Experimental verification of bremsstrahlung production and dosimetry predictions for 15.5 MeV electrons

    SciTech Connect

    Sanford, T.W.L.; Beutler, D.E.; Halbleib, J.A.; Knott, D.P.

    1991-11-01

    The radiation produced by a 15.5-Mev mono-energetic electron beam incident on optimized and non-optimized bremsstrahlung targets is characterized using the ITS Monte Carlo code and measurements with equilibrated and non-equilibrated TLD dosimetry. Comparisons between calculations and measurements verify the calculations and demonstrate that the code can be used to predict both bremsstrahlung production and TLD response for radiation fields that are characteristic of those produced by pulsed simulators of gamma rays. At optimum bremsstrahlung production, the predicted total forward radiation fluence detected in equilibrated TLD dosimetry agrees with that measured within the {plus_minus}6% uncertainty of the measurement. The absolute comparisons made here provide independent confirmation of the validity of the TLD calibration for photon fields characteristic of gamma-ray simulators. The empirical Martin equation, which is often used to calculate radiation dose from optimized bremsstrahlung targets, is examined, and its range of validity is established from the data presented.

  13. Non-Target Activity Detection by Post-Radioembolization Yttrium-90 PET/CT: Image Assessment Technique and Case Examples

    PubMed Central

    Kao, Yung Hsiang; Tan, Andrew E. H.; Lo, Richard H. G.; Tay, Kiang Hiong; Tan, Bien Soo; Chow, Pierce K. H.; Ng, David C. E.; Goh, Anthony S. W.

    2013-01-01

    High resolution yttrium-90 (90Y) imaging of post-radioembolization microsphere biodistribution may be achieved by conventional positron emission tomography with integrated computed tomography (PET/CT) scanners that have time-of-flight capability. However, reconstructed 90Y PET/CT images have high background noise, making non-target activity detection technically challenging. This educational article describes our image assessment technique for non-target activity detection by 90Y PET/CT, which qualitatively overcomes the problem of background noise. We present selected case examples of non-target activity in untargeted liver, stomach, gallbladder, chest wall, and kidney, supported by angiography and 90Y bremsstrahlung single-photon emission computed tomography with integrated computed tomography (SPECT/CT) or technetium-99m macroaggregated albumin SPECT/CT. PMID:24551594

  14. Monte Carlo scatter correction for SPECT

    NASA Astrophysics Data System (ADS)

    Liu, Zemei

    The goal of this dissertation is to present a quantitatively accurate and computationally fast scatter correction method that is robust and easily accessible for routine applications in SPECT imaging. A Monte Carlo based scatter estimation method is investigated and developed further. The Monte Carlo simulation program SIMIND (Simulating Medical Imaging Nuclear Detectors), was specifically developed to simulate clinical SPECT systems. The SIMIND scatter estimation (SSE) method was developed further using a multithreading technique to distribute the scatter estimation task across multiple threads running concurrently on multi-core CPU's to accelerate the scatter estimation process. An analytical collimator that ensures less noise was used during SSE. The research includes the addition to SIMIND of charge transport modeling in cadmium zinc telluride (CZT) detectors. Phenomena associated with radiation-induced charge transport including charge trapping, charge diffusion, charge sharing between neighboring detector pixels, as well as uncertainties in the detection process are addressed. Experimental measurements and simulation studies were designed for scintillation crystal based SPECT and CZT based SPECT systems to verify and evaluate the expanded SSE method. Jaszczak Deluxe and Anthropomorphic Torso Phantoms (Data Spectrum Corporation, Hillsborough, NC, USA) were used for experimental measurements and digital versions of the same phantoms employed during simulations to mimic experimental acquisitions. This study design enabled easy comparison of experimental and simulated data. The results have consistently shown that the SSE method performed similarly or better than the triple energy window (TEW) and effective scatter source estimation (ESSE) methods for experiments on all the clinical SPECT systems. The SSE method is proven to be a viable method for scatter estimation for routine clinical use.

  15. Gas bremsstrahlung shielding calculation for first optic enclosure of ILSF medical beamline

    NASA Astrophysics Data System (ADS)

    Beigzadeh Jalali, H.; Salimi, E.; Rahighi, J.

    2016-10-01

    Gas bremsstrahlung is generated in high energy electron storage ring accompanies the synchrotron radiation into the beamlines and strike the various components of the beamline. In this paper, radiation shielding calculation for secondary gas bremsstrahlung is performed for the first optics enclosure (FOE) of medical beamline of the Iranian Light Source Facility (ILSF). Dose equivalent rate (DER) calculation is accomplished using FLUKA Monte Carlo code. A comprehensive study of DER distribution at the back wall, sides and roof is given.

  16. Screening Effects on Nonrelativistic Bremsstrahlung in the Scattering of Electrons by Neutral Atoms

    NASA Technical Reports Server (NTRS)

    Jung, Young-Dae; Lee, Kun-Sang

    1995-01-01

    Atomic screening effects on nonrelativistic electron-atom bremsstrahlung radiation are investigated using a simple analytic solution of the Thomas-Fermi model for many-electron atoms. The Born approximation is assumed for the initial and final states of the projectile electron. The results show that the screening effect is important in the soft radiation region and is decreasing with increasing radiation. These results help provide correct information about the behavior of bound electrons in the target atom in bremsstrahlung processes.

  17. Optimizing the beam-beam alignment in an electron lens using bremsstrahlung

    SciTech Connect

    Montag, C.; Fischer, W.; Gassner, D.; Thieberger, P.; Haug, E.

    2010-05-23

    Installation of electron lenses for the purpose of head-on beam-beam compensation is foreseen at RHIC. To optimize the relative alignment of the electron lens beam with the circulating proton (or ion) beam, photon detectors will be installed to measure the bremsstrahlung generated by momentum transfer from protons to electrons. We present the detector layout and simulations of the bremsstrahlung signal as function of beam offset and crossing angle.

  18. Proof of Principle for Active Detection of Fissionable Material Using Intense, Pulsed-Bremsstrahlung-Induced Photofission

    DTIC Science & Technology

    2014-10-07

    Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6770--14-9554 Proof of Principle for Active Detection of Fissionable Material Using...of Fissionable Material Using Intense, Pulsed-Bremsstrahlung-Induced Photofission R.J. Commisso, J.W. Schumer, R.J. Allen, D.D. Hinshelwood, S.L...induce photofission in fissile material . We are investigating the applicability of this mechanism, using photons from bremsstrahlung, for long-range

  19. Role of Bremsstrahlung Radiation in Limiting the Energy of Runaway Electrons in Tokamaks

    SciTech Connect

    Bakhtiari, M.; Takechi, M.; Tamai, H.; Miura, Y.; Kusama, Y.; Kamada, Y.; Kramer, G.J.

    2005-06-03

    Bremsstrahlung radiation of runaway electrons is found to be an energy limit for runaway electrons in tokamaks. The minimum and maximum energy of runaway electron beams is shown to be limited by collisions and bremsstrahlung radiation, respectively. It is also found that a massive injection of a high-Z gas such as xenon can terminate a disruption-generated runaway current before the runaway electrons hit the walls.

  20. Nuclear effects on neutrino emissivities from nucleon-nucleon bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Stoica, S.; Paun, V. P.; Negoita, A. G.

    2004-06-01

    The rates of neutrino pair emission by nucleon-nucleon (NN) bremsstrahlung are calculated with the inclusion of the full contribution from a nuclear one pion exchange potential (OPEP). We compute the contributions from the neutron-neutron (nn), proton-proton (pp), and neutron-proton (np) processes for physical conditions encountered in supernovae and neutron stars, both in the degenerate (D) and nondegenerate (ND) limits. We find a significant reduction of these rates, especially for the nn and pp processes, in comparison with the case when the whole nuclear contribution was replaced by constants, representing the high-momentum limits of the expressions of the nuclear potential. Furthermore, we also perform the calculations by including contributions due to the ρ meson exchange between nucleons, in the OPEP. This may be relevant for processes produced in the inner core of neutron stars, where the density may exceed several times the standard nuclear density, and the short-range part of the NN interaction should be taken into account. These corrections lead to an additional suppression of the neutrino emission rates between (8 and 36)%, depending on the process [nn (pp) or np] and physical conditions (temperature and degeneracy of the nucleons).

  1. Bremsstrahlung from an equilibrating quark-gluon plasma

    NASA Astrophysics Data System (ADS)

    Mustafa, Munshi G.; Thoma, Markus H.

    2000-07-01

    The photon production rate from a chemically equilibrating quark-gluon plasma likely to be produced at RHIC (BNL) and LHC (CERN) energies is estimated taking into account bremsstrahlung. The plasma is assumed to be in local thermal equilibrium, but with a phase space distribution that deviates from the Fermi or Bose distribution by space-time dependent factors (fugacities). The photon spectrum is obtained by integrating the photon rate over the space-time history of the plasma, adopting a boost invariant cylindrically symmetric transverse expansion of the system with different nuclear profile functions. Initial conditions obtained from a self-screened parton cascade calculation and, for comparison, from the HIJING model are used. Compared to an equilibrated plasma at the same initial energy density, taken from the self-screened parton cascade, a moderate suppression of the photon yield by a factor of 1 to 5 depending on the collision energy and the photon momentum is observed. The individual contributions to the photon production, however, are completely different in the both scenarios.

  2. Polarization of thermal bremsstrahlung emission due to electron pressure anisotropy

    NASA Astrophysics Data System (ADS)

    Komarov, S. V.; Khabibullin, I. I.; Churazov, E. M.; Schekochihin, A. A.

    2016-09-01

    Astrophysical plasmas are typically magnetized, with the Larmor radii of the charged particles many orders of magnitude smaller than their collisional mean free paths. The fundamental properties of such plasmas, e.g. conduction and viscosity, may depend on the instabilities driven by the anisotropy of the particle distribution functions and operating at scales comparable to the Larmor scales. We discuss a possibility that the pressure anisotropy of thermal electrons could produce polarization of thermal bremsstrahlung emission. In particular, we consider coherent large-scale motions in galaxy clusters to estimate the level of anisotropy driven by stretching of the magnetic-field lines by plasma flow and by heat fluxes associated with thermal gradients. Our estimate of the degree of polarization is ˜0.1 per cent at energies ≳kT. While this value is too low for the forthcoming generation of X-ray polarimeters, it is potentially an important proxy for the processes taking place at extremely small scales, which are impossible to resolve spatially. The absence of the effect at the predicted level may set a lower limit on the electron collisionality in the ICM. At the same time, the small value of the effect implies that it does not preclude the use of clusters as (unpolarized) calibration sources for X-ray polarimeters at this level of accuracy.

  3. SPECT (single photon emission computed tomography) in pediatrics.

    PubMed

    Chiron, Catherine

    2013-01-01

    Surgery of focal epilepsies in childhood has largely benefited from the recent advances of the noninvasive functional imaging techniques, particularly SPECT which presurgically contributes to the localization of the seizure onset zone, in order to select the patients, decide the optimal placement of intracranial electrodes, and plan the resection. Peri-ictal SPECT (ictal and postictal) proved especially useful when video-EEG is not contributory, when MRI looks normal or shows multiple abnormalities, or in cases of discrepant findings within the presurgery workup. Because of a poor temporal resolution, peri-ictal SPECT must be coupled with video-EEG. Multimodal imaging so-called SISCOM (peri-ictal - interictal SPECT subtraction image superimposed on MRI) increases the sensitivity of peri-ictal SPECT by about 70% and makes it a good predictor of seizure-free outcome after surgery. In addition, interictal SPECT occasionally provides some interesting results regarding functional cortical maturation and learning disorders in childhood.

  4. Influence of the electron-exchange and quantum shielding on the bremsstrahlung spectrum in degenerate quantum plasmas

    NASA Astrophysics Data System (ADS)

    Jung, Young-Dae

    2013-10-01

    The influence of the electron-exchange and quantum shielding on the bremsstrahlung spectrum is investigated in degenerate quantum plasmas. The impact-parameter analysis with the Shukla-Eliasson potential is applied to obtain the electron-ion bremsstrahlung radiation cross section as a function of the impact parameter, photon energy, projectile energy, electron-exchange parameter, Fermi energy, and plasmon energy. The result shows that the electron-exchange effect strongly enhances the bremsstrahlung radiation spectrum in degenerate quantum plasmas. It is also shown that the influence of the electron-exchange broadens the photon emission range in the electron-ion bremsstrahlung process. It is found that the electron-exchange effect focuses the bremsstrahlung photon energy in the soft photon domain. In addition, it is found that the bremsstrahlung radiation cross section increases with an increase of the Fermi energy and, however, decreases with increasing plasmon energy.

  5. Local injection of the 90Y-labelled peptidic vector DOTATOC to control gliomas of WHO grades II and III: an extended pilot study.

    PubMed

    Schumacher, T; Hofer, S; Eichhorn, K; Wasner, M; Zimmerer, S; Freitag, P; Probst, A; Gratzl, O; Reubi, J-C; Maecke, R; Mueller-Brand, J; Merlo, A

    2002-04-01

    We have previously presented preliminary observations on targeting somatostatin receptor-positive malignant gliomas of all grades by local injection of the radiolabelled peptidic vector 90Y-DOTATOC. We now report on our more thorough clinical experience with this novel compound, focussing on low-grade and anaplastic gliomas. Small peptidic vectors have the potential to target invisible infiltrative disease within normal surrounding brain tissue, thereby opening a window of opportunity for early intervention. Five progressive gliomas of WHO grades II and III and five extensively debulked low-grade gliomas were treated with varying fractions of 90Y-DOTATOC. The vectors were locally injected into the resection cavity or into solid tumour. The activity per single injection ranged from 555 to 1,875 MBq, and the cumulative activity from 555 to 7,030 MBq, according to tumour volumes and eloquence of the affected brain area, yielding dose estimates from 76+/-15 to 312+/-62 Gy. Response was assessed by the clinical status, by steroid dependence and, every 4-6 months, by magnetic resonance imaging and fluorine-18 fluorodeoxyglucose positron emission tomography. In the five progressive gliomas, lasting responses were obtained for at least 13-45 months without the need for steroids. Radiopeptide brachytherapy had been the only modality applied to counter tumour progression. Interestingly, we observed the slow transformation of a solid, primarily inoperable anaplastic astrocytoma into a resectable multi-cystic lesion 2 years after radiopeptide brachytherapy. Based on these observations, we also assessed the feasibility of local radiotherapy following extensive debulking, which was well tolerated. Targeted beta-particle irradiation based on diffusible small peptidic vectors appears to be a promising modality for the treatment of malignant gliomas.

  6. Functional neuroimaging in epilepsy: FDG PET and ictal SPECT.

    PubMed Central

    Lee, D. S.; Lee, S. K.; Lee, M. C.

    2001-01-01

    Epileptogenic zones can be localized by F-18 fluorodeoxyglucose positron emission tomography (FDG PET) and ictal single-photon emission computed tomography(SPECT). In medial temporal lobe epilepsy, the diagnostic sensitivity of FDG PET or ictal SPECT is excellent, however, the sensitivity of MRI is so high that the incremental sensitivity by FDG PET or ictal SPECT has yet to be proven. When MRI findings are ambiguous or normal, or discordant with those of ictal EEG, FDG PET and ictal SPECT are helpful for localization without the need for invasive ictal EEG. In neocortical epilepsy, the sensitivities of FDG PET or ictal SPECT are fair. However, because almost a half of the patients are normal on MRI, FDG PET and ictal SPECT are helpful for localization or at least for lateralization in these non-lesional epilepsies in order to guide the subdural insertion of electrodes. Interpretation of FDG PET has been recently advanced by voxel-based analysis and automatic volume of interest analysis based on a population template. Both analytical methods confirmed the performance of previous visual interpretation results. Ictal SPECT was analyzed using subtraction methods(coregistered to MRI) and voxel-based analysis. Rapidity of injection of tracers, HMPAO versus ECD, and repeated ictal SPECT, which remain the technical issues of ictal SPECT, are detailed. PMID:11748346

  7. Silicon Detectors for PET and SPECT

    NASA Astrophysics Data System (ADS)

    Cochran, Eric R.

    Silicon detectors use state-of-the-art electronics to take advantage of the semiconductor properties of silicon to produce very high resolution radiation detectors. These detectors have been a fundamental part of high energy, nuclear, and astroparticle physics experiments for decades, and they hold great potential for significant gains in both PET and SPECT applications. Two separate prototype nuclear medicine imaging systems have been developed to explore this potential. Both devices take advantage of the unique properties of high resolution pixelated silicon detectors, designed and developed as part of the CIMA collaboration and built at The Ohio State University. The first prototype is a Compton SPECT imaging system. Compton SPECT, also referred to as electronic collimation, is a fundamentally different approach to single photon imaging from standard gamma cameras. It removes the inherent coupling of spatial resolution and sensitivity in mechanically collimated systems and provides improved performance at higher energies. As a result, Compton SPECT creates opportunities for the development of new radiopharmaceuticals based on higher energy isotopes as well as opportunities to expand the use of current isotopes such as 131I due to the increased resolution and sensitivity. The Compton SPECT prototype consists of a single high resolution silicon detector, configured in a 2D geometry, in coincidence with a standard NaI scintillator detector. Images of point sources have been taken for 99mTc (140 keV), 131I (364keV), and 22Na (511 keV), demonstrating the performance of high resolution silicon detectors in a Compton SPECT system. Filtered back projection image resolutions of 10 mm, 7.5 mm, and 6.7 mm were achieved for the three different sources respectively. The results compare well with typical SPECT resolutions of 5-15 mm and validate the claims of improved performance in Compton SPECT imaging devices at higher source energies. They also support the potential of

  8. Accelerated GPU based SPECT Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Garcia, Marie-Paule; Bert, Julien; Benoit, Didier; Bardiès, Manuel; Visvikis, Dimitris

    2016-06-01

    Monte Carlo (MC) modelling is widely used in the field of single photon emission computed tomography (SPECT) as it is a reliable technique to simulate very high quality scans. This technique provides very accurate modelling of the radiation transport and particle interactions in a heterogeneous medium. Various MC codes exist for nuclear medicine imaging simulations. Recently, new strategies exploiting the computing capabilities of graphical processing units (GPU) have been proposed. This work aims at evaluating the accuracy of such GPU implementation strategies in comparison to standard MC codes in the context of SPECT imaging. GATE was considered the reference MC toolkit and used to evaluate the performance of newly developed GPU Geant4-based Monte Carlo simulation (GGEMS) modules for SPECT imaging. Radioisotopes with different photon energies were used with these various CPU and GPU Geant4-based MC codes in order to assess the best strategy for each configuration. Three different isotopes were considered: 99m Tc, 111In and 131I, using a low energy high resolution (LEHR) collimator, a medium energy general purpose (MEGP) collimator and a high energy general purpose (HEGP) collimator respectively. Point source, uniform source, cylindrical phantom and anthropomorphic phantom acquisitions were simulated using a model of the GE infinia II 3/8" gamma camera. Both simulation platforms yielded a similar system sensitivity and image statistical quality for the various combinations. The overall acceleration factor between GATE and GGEMS platform derived from the same cylindrical phantom acquisition was between 18 and 27 for the different radioisotopes. Besides, a full MC simulation using an anthropomorphic phantom showed the full potential of the GGEMS platform, with a resulting acceleration factor up to 71. The good agreement with reference codes and the acceleration factors obtained support the use of GPU implementation strategies for improving computational efficiency

  9. Accelerated GPU based SPECT Monte Carlo simulations.

    PubMed

    Garcia, Marie-Paule; Bert, Julien; Benoit, Didier; Bardiès, Manuel; Visvikis, Dimitris

    2016-06-07

    Monte Carlo (MC) modelling is widely used in the field of single photon emission computed tomography (SPECT) as it is a reliable technique to simulate very high quality scans. This technique provides very accurate modelling of the radiation transport and particle interactions in a heterogeneous medium. Various MC codes exist for nuclear medicine imaging simulations. Recently, new strategies exploiting the computing capabilities of graphical processing units (GPU) have been proposed. This work aims at evaluating the accuracy of such GPU implementation strategies in comparison to standard MC codes in the context of SPECT imaging. GATE was considered the reference MC toolkit and used to evaluate the performance of newly developed GPU Geant4-based Monte Carlo simulation (GGEMS) modules for SPECT imaging. Radioisotopes with different photon energies were used with these various CPU and GPU Geant4-based MC codes in order to assess the best strategy for each configuration. Three different isotopes were considered: (99m) Tc, (111)In and (131)I, using a low energy high resolution (LEHR) collimator, a medium energy general purpose (MEGP) collimator and a high energy general purpose (HEGP) collimator respectively. Point source, uniform source, cylindrical phantom and anthropomorphic phantom acquisitions were simulated using a model of the GE infinia II 3/8" gamma camera. Both simulation platforms yielded a similar system sensitivity and image statistical quality for the various combinations. The overall acceleration factor between GATE and GGEMS platform derived from the same cylindrical phantom acquisition was between 18 and 27 for the different radioisotopes. Besides, a full MC simulation using an anthropomorphic phantom showed the full potential of the GGEMS platform, with a resulting acceleration factor up to 71. The good agreement with reference codes and the acceleration factors obtained support the use of GPU implementation strategies for improving computational

  10. New Approaches in SPECT Breast Imaging

    DTIC Science & Technology

    2005-07-01

    the use of their breast and torso phantoms. The software package, "SPECTER", developed by Tim Turkington, was used to analyze and display the phantom...breast images. The software package, "SPECT-MAP", developed by James Bowsher, was used for reconstructions. VI. REFERENCES [1] Tornai MP, Bowsher JE...based software . and standard errors of the mean. No attenuation or scatter corrections were taken into account in For a given statistical ensemble of

  11. Measurements and analysis of bremsstrahlung x-ray spectrum obtained in NANOGAN electron cyclotron resonance ion source

    SciTech Connect

    Baskaran, R.; Selvakumaran, T. S.; Rodrigues, G.; Kanjilal, D.; Roy, A.

    2008-02-15

    From the ECR plasma, hot electrons leak across the magnetic lines of force and by striking the plasma chamber produce bremsstrahlung x-rays. The wall bremsstrahlung gives information on the confinement status of hot electron. In our studies, experimental measurements are carried out in NANOGAN electron cyclotron resonance (ECR) ion source for the wall bremsstrahlung x-rays and the results are presented. While optimizing a particular charge state in ECR ion source, experimental parameters are adjusted to get a maximum current. The wall bremsstrahlung components are studied in these cases for understanding the hot electron confinement conditions.

  12. SPECT and PET in ischemic heart failure.

    PubMed

    Angelidis, George; Giamouzis, Gregory; Karagiannis, Georgios; Butler, Javed; Tsougos, Ioannis; Valotassiou, Varvara; Giannakoulas, George; Dimakopoulos, Nikolaos; Xanthopoulos, Andrew; Skoularigis, John; Triposkiadis, Filippos; Georgoulias, Panagiotis

    2017-02-02

    Heart failure is a common clinical syndrome associated with significant morbidity and mortality worldwide. Ischemic heart disease is the leading cause of heart failure, at least in the industrialized countries. Proper diagnosis of the syndrome and management of patients with heart failure require anatomical and functional information obtained through various imaging modalities. Nuclear cardiology techniques play a main role in the evaluation of heart failure. Myocardial single photon emission computed tomography (SPECT) with thallium-201 or technetium-99 m labelled tracers offer valuable data regarding ventricular function, myocardial perfusion, viability, and intraventricular synchronism. Moreover, positron emission tomography (PET) permits accurate evaluation of myocardial perfusion, metabolism, and viability, providing high-quality images and the ability of quantitative analysis. As these imaging techniques assess different parameters of cardiac structure and function, variations of sensitivity and specificity have been reported among them. In addition, the role of SPECT and PET guided therapy remains controversial. In this comprehensive review, we address these controversies and report the advances in patient's investigation with SPECT and PET in ischemic heart failure. Furthermore, we present the innovations in technology that are expected to strengthen the role of nuclear cardiology modalities in the investigation of heart failure.

  13. SPECT and PET Imaging of Meningiomas

    PubMed Central

    Valotassiou, Varvara; Leondi, Anastasia; Angelidis, George; Psimadas, Dimitrios; Georgoulias, Panagiotis

    2012-01-01

    Meningiomas arise from the meningothelial cells of the arachnoid membranes. They are the most common primary intracranial neoplasms and represent about 20% of all intracranial tumors. They are usually diagnosed after the third decade of life and they are more frequent in women than in men. According to the World Health Organization (WHO) criteria, meningiomas can be classified into grade I meningiomas, which are benign, grade II (atypical) and grade III (anaplastic) meningiomas, which have a much more aggressive clinical behaviour. Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) are routinely used in the diagnostic workup of patients with meningiomas. Molecular Nuclear Medicine Imaging with Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) could provide complementary information to CT and MRI. Various SPECT and PET tracers may provide information about cellular processes and biological characteristics of meningiomas. Therefore, SPECT and PET imaging could be used for the preoperative noninvasive diagnosis and differential diagnosis of meningiomas, prediction of tumor grade and tumor recurrence, response to treatment, target volume delineation for radiation therapy planning, and distinction between residual or recurrent tumour from scar tissue. PMID:22623896

  14. SPECT and PET imaging of meningiomas.

    PubMed

    Valotassiou, Varvara; Leondi, Anastasia; Angelidis, George; Psimadas, Dimitrios; Georgoulias, Panagiotis

    2012-01-01

    Meningiomas arise from the meningothelial cells of the arachnoid membranes. They are the most common primary intracranial neoplasms and represent about 20% of all intracranial tumors. They are usually diagnosed after the third decade of life and they are more frequent in women than in men. According to the World Health Organization (WHO) criteria, meningiomas can be classified into grade I meningiomas, which are benign, grade II (atypical) and grade III (anaplastic) meningiomas, which have a much more aggressive clinical behaviour. Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) are routinely used in the diagnostic workup of patients with meningiomas. Molecular Nuclear Medicine Imaging with Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) could provide complementary information to CT and MRI. Various SPECT and PET tracers may provide information about cellular processes and biological characteristics of meningiomas. Therefore, SPECT and PET imaging could be used for the preoperative noninvasive diagnosis and differential diagnosis of meningiomas, prediction of tumor grade and tumor recurrence, response to treatment, target volume delineation for radiation therapy planning, and distinction between residual or recurrent tumour from scar tissue.

  15. Reconstruction of dynamic gated cardiac SPECT

    SciTech Connect

    Jin Mingwu; Yang Yongyi; King, Michael A.

    2006-11-15

    In this paper we propose an image reconstruction procedure which aims to unify gated single photon emission computed tomography (SPECT) and dynamic SPECT into a single method. We divide the cardiac cycle into a number of gate intervals as in gated SPECT, but treat the tracer distribution for each gate as a time-varying signal. By using both dynamic and motion-compensated temporal regularization, our reconstruction procedure will produce an image sequence that shows both cardiac motion and time-varying tracer distribution simultaneously. To demonstrate the proposed reconstruction method, we simulated gated cardiac perfusion imaging using the gated mathematical cardiac-torso (gMCAT) phantom with Tc99m-Teboroxime as the imaging agent. Our results show that the proposed method can produce more accurate reconstruction of gated dynamic images than independent reconstruction of individual gate frames with spatial smoothness alone. In particular, our results show that the former could improve the contrast to noise ratio of a simulated perfusion defect by as much as 100% when compared to the latter.

  16. SPECT detectors: the Anger Camera and beyond

    PubMed Central

    Peterson, Todd E.; Furenlid, Lars R.

    2011-01-01

    The development of radiation detectors capable of delivering spatial information about gamma-ray interactions was one of the key enabling technologies for nuclear medicine imaging and, eventually, single-photon emission computed tomography (SPECT). The continuous NaI(Tl) scintillator crystal coupled to an array of photomultiplier tubes, almost universally referred to as the Anger Camera after its inventor, has long been the dominant SPECT detector system. Nevertheless, many alternative materials and configurations have been investigated over the years. Technological advances as well as the emerging importance of specialized applications, such as cardiac and preclinical imaging, have spurred innovation such that alternatives to the Anger Camera are now part of commercial imaging systems. Increased computing power has made it practical to apply advanced signal processing and estimation schemes to make better use of the information contained in the detector signals. In this review we discuss the key performance properties of SPECT detectors and survey developments in both scintillator and semiconductor detectors and their readouts with an eye toward some of the practical issues at least in part responsible for the continuing prevalence of the Anger Camera in the clinic. PMID:21828904

  17. SPECT detectors: the Anger Camera and beyond

    NASA Astrophysics Data System (ADS)

    Peterson, Todd E.; Furenlid, Lars R.

    2011-09-01

    The development of radiation detectors capable of delivering spatial information about gamma-ray interactions was one of the key enabling technologies for nuclear medicine imaging and, eventually, single-photon emission computed tomography (SPECT). The continuous sodium iodide scintillator crystal coupled to an array of photomultiplier tubes, almost universally referred to as the Anger Camera after its inventor, has long been the dominant SPECT detector system. Nevertheless, many alternative materials and configurations have been investigated over the years. Technological advances as well as the emerging importance of specialized applications, such as cardiac and preclinical imaging, have spurred innovation such that alternatives to the Anger Camera are now part of commercial imaging systems. Increased computing power has made it practical to apply advanced signal processing and estimation schemes to make better use of the information contained in the detector signals. In this review we discuss the key performance properties of SPECT detectors and survey developments in both scintillator and semiconductor detectors and their readouts with an eye toward some of the practical issues at least in part responsible for the continuing prevalence of the Anger Camera in the clinic.

  18. Gas bremsstrahlung studies for medium energy electron storage rings using FLUKA Monte Carlo code

    NASA Astrophysics Data System (ADS)

    Sahani, Prasanta Kumar; Haridas, G.; Sinha, Anil K.; Hannurkar, P. R.

    2016-02-01

    Gas bremsstrahlung is generated due to the interaction of the stored electron beam with residual gas molecules of the vacuum chamber in a storage ring. As the opening angle of the bremsstrahlung is very small, the scoring area used in Monte Carlo simulation plays a dominant role in evaluating the absorbed dose. In the present work gas bremsstrahlung angular distribution and absorbed dose for the energies ranging from 1 to 5 GeV electron storage rings are studied using the Monte Carlo code, FLUKA. From the study, an empirical formula for gas bremsstrahlung dose estimation was deduced. The results were compared with the data obtained from reported experimental values. The results obtained from simulations are found to be in very good agreement with the reported experimental data. The results obtained are applied in estimating the gas bremsstrahlung dose for 2.5 GeV synchrotron radiation source, Indus-2 at Raja Ramanna Centre for Advanced Technology, India. The paper discusses the details of the simulation and the results obtained.

  19. Z-dependence of thick-target bremsstrahlung produced by monoenergetic low-energy electrons

    NASA Astrophysics Data System (ADS)

    Czarnecki, S.; Short, A.; Williams, S.

    2016-07-01

    The dependence of thick-target bremsstrahlung emitted by low-energy beams of monoenergetic electrons on the atomic number of the target material has been investigated experimentally for incident electron energies of 4.25 keV and 5.00 keV using thick aluminum, copper, silver, tungsten, and gold targets. Experimental data suggest that the intensity of the thick-target bremsstrahlung emitted is more strongly dependent on the atomic number of the target material for photons with energies that are approximately equal to the energy of the incident electrons than at lower energies, and also that the dependence of thick-target bremsstrahlung on the atomic number of the target material is stronger for incident electrons of higher energies than for incident electrons of lower energies. The results of the experiments are compared to the results of simulations performed using the PENELOPE program (which is commonly used in medical physics) and to thin-target bremsstrahlung theory, as well. Comparisons suggest that the experimental dependence of thick-target bremsstrahlung on the atomic number of the target material may be slightly stronger than the results of the PENELOPE code suggest.

  20. The influence of bremsstrahlung on electric discharge streamers in N2, O2 gas mixtures

    NASA Astrophysics Data System (ADS)

    Köhn, C.; Chanrion, O.; Neubert, T.

    2017-01-01

    Streamers are ionization filaments of electric gas discharges. Negative polarity streamers propagate primarily through electron impact ionization, whereas positive streamers in air develop through ionization of oxygen by UV photons emitted by excited nitrogen; however, experiments show that positive streamers may develop even for low oxygen concentrations. Here we explore if bremsstrahlung ionization facilitates positive streamer propagation. To discriminate between effects of UV and bremsstrahlung ionization, we simulate the formation of a double headed streamer at three different oxygen concentrations: no oxygen, 1 ppm O2 and 20% O2, as in air. At these oxygen levels, UV-relative to bremsstrahlung ionization is zero, small, and large. The simulations are conducted with a particle-in-cell code in a cylindrically symmetric configuration at ambient electric field magnitudes three times the conventional breakdown field. We find that bremsstrahlung induced ionization in air, contrary to expectations, reduces the propagation velocity of both positive and negative streamers by about 15%. At low oxygen levels, positive streamers stall; however, bremsstrahlung creates branching sub-streamers emerging from the streamer front that allow propagation of the streamer. Negative streamers propagate more readily forming branching sub-streamers. These results are in agreement with experiments. At both polarities, ionization patches are created ahead of the streamer front. Electrons with the highest energies are in the sub-streamer tips and the patches.

  1. Inverse Bremsstrahlung Heating in Laser-Matter Interactions: the effects of other particles

    NASA Astrophysics Data System (ADS)

    Pandit, Rishi; Sentoku, Yasuhiko; Ackad, Edward

    2016-10-01

    The laser-matter interaction of inverse bremsstrahlung heating is studied via a particle in cell code, PICLS and via molecular dynamics code, MD. Inverse bremsstrahlung heating, an important process in the laser-matter interaction, involves three different kinds of interactions, i)the interaction of the electrons with the external laser field, ii) the electron-ion interaction and iii) the electron-electron interaction. In the interaction of atomic clusters with femtosecond laser pulses, nanoplasmas with high density are created. A new scaling for the rate of energy absorption in inverse bremsstrahlung heating has been derived which depends on the external laser field as well as electric field due to the other particles. Electric fields due to the particles depend on a parameter, the potential depth. Thus, inverse bremsstrahlung heating also depends on potential depth. We will discuss the particle in cell code results and molecular dynamics code results by varying laser intensities and potential depths to understand the effect of potential depth as well as the particle's field's dependence of inverse bremsstrahlung heating in laser-matter interaction. This work was supported by Air Force Office of Scientific Research under AFOSR Award No. FA9550-14-1-0247.

  2. Contribution of 210Pb bremsstrahlung to the background of lead shielded gamma spectrometers

    NASA Astrophysics Data System (ADS)

    Mrđa, D.; Bikit, I.; Vesković, M.; Forkapić, S.

    2007-03-01

    Lead, which is often used as a shielding material, contains 210Pb ( T1/2=22.3 y). The 46.54 keV γ-intensity of 210Pb can be easily reduced by an inner lining, but the bremsstrahlung caused by the β-decay of its daughter, 210Bi, with a maximal electron energy of 1.16 MeV, will contribute to the gamma detector background. The spectrum of this bremsstrahlung is calculated by numerically fitting the β-spectrum and integrating the Koch-Motz formula. The absorption of the bremsstrahlung in the lead and detection efficiencies for the HPGe detector are calculated by the effective solid angle algorithm, using corrections for the photopeak/Compton ratio of cross-sections in Ge. By comparison with the measured background spectrum, it is shown that, for the lead with 25 Bq/kg of 210Pb up to 500 keV of gamma spectrum, the bremsstrahlung contribution to the background is about 20% for our surface-based detector system. Also, we compared our calculations with a Monte Carlo simulation of another detector system with a shield containing 1 Bq/kg of 210Pb and found that our analytical method gives a value of roughly two times higher than the Monte Carlo one for the total bremsstrahlung contribution. The quality of the analytical semi-empirical method is proved by the reasonable agreement with the experimental results published.

  3. Design and assessment of cardiac SPECT systems

    NASA Astrophysics Data System (ADS)

    Lee, Chih-Jie

    Single-photon emission computed tomography (SPECT) is a modality widely used to detect myocardial ischemia and myocardial infarction. Objectively assessing and comparing different SPECT systems is important so that the best detectability of cardiac defects can be achieved. Whitaker, Clarkson, and Barrett's study on the scanning linear observer (SLO) shows that the SLO can be used to estimate the location and size of signals. One major advantage of the SLO is that it can be used with projection data rather than reconstruction data. Thus, this observer model assesses overall hardware performance independent by any reconstruction algorithm. In addition, we will show that the run time of image-quality studies is significantly reduced. Several systems derived from the GE CZT-based dedicated cardiac SPECT camera Discovery 530c design, which is officially named the Alcyone Technology: Discovery NM 530c, were assessed using the performance of the SLO for the task of detecting cardiac defects and estimating the properties of the defects. Clinically, hearts can be virtually segmented into three coronary artery territories: left anterior descending artery (LAD), left circumflex artery (LCX), and right coronary artery (RCA). One of the most important functions of a cardiac SPECT system is to produce images from which a radiologist can correctly predict in which territory the defect exists. A good estimation of the defect extent from the images is also very helpful for determining the seriousness of the myocardial ischemia. In this dissertation, both locations and extent of defects were estimated by the SLO, and system performance was assessed using localization receiver operating characteristic (LROC) / estimation receiver operating characteristic (EROC) curves. Area under LROC curve (AULC) / area under EROC curve (AUEC) and true positive fraction (TPF) at specific false positive fraction (FPF) can be treated as the gures of merit (FOMs). As the results will show, a

  4. Quantitative Monte Carlo-based holmium-166 SPECT reconstruction

    SciTech Connect

    Elschot, Mattijs; Smits, Maarten L. J.; Nijsen, Johannes F. W.; Lam, Marnix G. E. H.; Zonnenberg, Bernard A.; Bosch, Maurice A. A. J. van den; Jong, Hugo W. A. M. de; Viergever, Max A.

    2013-11-15

    Purpose: Quantitative imaging of the radionuclide distribution is of increasing interest for microsphere radioembolization (RE) of liver malignancies, to aid treatment planning and dosimetry. For this purpose, holmium-166 ({sup 166}Ho) microspheres have been developed, which can be visualized with a gamma camera. The objective of this work is to develop and evaluate a new reconstruction method for quantitative {sup 166}Ho SPECT, including Monte Carlo-based modeling of photon contributions from the full energy spectrum.Methods: A fast Monte Carlo (MC) simulator was developed for simulation of {sup 166}Ho projection images and incorporated in a statistical reconstruction algorithm (SPECT-fMC). Photon scatter and attenuation for all photons sampled from the full {sup 166}Ho energy spectrum were modeled during reconstruction by Monte Carlo simulations. The energy- and distance-dependent collimator-detector response was modeled using precalculated convolution kernels. Phantom experiments were performed to quantitatively evaluate image contrast, image noise, count errors, and activity recovery coefficients (ARCs) of SPECT-fMC in comparison with those of an energy window-based method for correction of down-scattered high-energy photons (SPECT-DSW) and a previously presented hybrid method that combines MC simulation of photopeak scatter with energy window-based estimation of down-scattered high-energy contributions (SPECT-ppMC+DSW). Additionally, the impact of SPECT-fMC on whole-body recovered activities (A{sup est}) and estimated radiation absorbed doses was evaluated using clinical SPECT data of six {sup 166}Ho RE patients.Results: At the same noise level, SPECT-fMC images showed substantially higher contrast than SPECT-DSW and SPECT-ppMC+DSW in spheres ≥17 mm in diameter. The count error was reduced from 29% (SPECT-DSW) and 25% (SPECT-ppMC+DSW) to 12% (SPECT-fMC). ARCs in five spherical volumes of 1.96–106.21 ml were improved from 32%–63% (SPECT-DSW) and 50%–80

  5. A small-animal imaging system capable of multipinhole circular/helical SPECT and parallel-hole SPECT

    PubMed Central

    Qian, Jianguo; Bradley, Eric L.; Majewski, Stan; Popov, Vladimir; Saha, Margaret S.; Smith, Mark F.; Weisenberger, Andrew G.; Welsh, Robert E.

    2008-01-01

    We have designed and built a small animal single photon emission computed tomography (SPECT) imaging system equipped with parallel-hole and multipinhole collimators and capable of circular or helical SPECT. Copper-beryllium parallel-hole collimators suitable for imaging the ~35 keV photons from the decay of 125I have been built and installed to achieve useful spatial resolution over a range of object-detector distances and to reduce imaging time on our dual-detector array. To address the resolution limitations in the parallel-hole SPECT and the sensitivity and limited field of view of single-pinhole SPECT, we have incorporated multipinhole circular and helical SPECT in addition to expanding the parallel-hole SPECT capabilities. The pinhole SPECT system is based on a 110 mm diameter circular detector equipped with a pixellated NaI(Tl) scintillator array (1×1×5 mm3/pixel). The helical trajectory is accomplished by two stepping motors controlling the rotation of the detector-support gantry and displacement of the animal bed along the axis of rotation of the gantry. Results obtained in SPECT studies of various phantoms show an enlarged field of view, very good resolution and improved sensitivity using multipinhole circular or helical SPECT. Collimators with one, three and five 1 mm diameter pinholes have been implemented and compared in these tests. Our objective is to develop a system on which one may readily select a suitable mode of either parallel-hole SPECT or pinhole circular or helical SPECT for a variety of small animal imaging applications. PMID:19701447

  6. Vector bremsstrahlung by ultrarelativistic collisions in higher dimensions

    NASA Astrophysics Data System (ADS)

    Constantinou, Yiannis; Spirin, Pavel

    2014-01-01

    A classical computation of vector bremsstrahlung in ultrarelativistic gravitational-force collisions of massive point particles is presented in an arbitrary number d of extra dimensions. Our method adapts the post-linear formalism of General Relativity to the multidimensional case. The total emitted energy, as well as its angular and frequency distribution and characteristic values, are discussed in detail. For an electromagnetic mediation propagated in the bulk, the emitted energy E em of scattering with impact parameter b has magnitude E em ~ e 4 e '2γ d+2 /( m 2 b 3 d+3), with dominant frequency ω em ~ γ2 /b. For the gravitational force the charge emits via vector field, propagated in the bulk, energy E rad ~ [ G D m ' e]2γ d+2 /b 3 d+3 for d ≥ 2, with dominant frequency ω ~ γ2 /b; and energy E rad ~ [ G 5 m ' e 5]2 γ3 ln γ /b 6 for d = 1, with most of the energy coming from a wide frequency region ω ∈ [(γ /b) , (γ2 /b)]. For the UED model with extra space volume V = (2 πR) d the emitted energy is E UED ~ ( b d /V)2 E rad. Finally, for the ADD model, including four dimensions, the electromagnetic field living on 3-brane, loses on emission the energy E ADD ~ [ G D m ' e]2 γ3 /( V b 2 d+3), with characteristic frequency ω ADD ~ γ /b. The contribution of the low frequency part of the radiation (soft photons) to the total radiated energy is shown to be negligible for all values of d. The domain of validity of the classical result is discussed. The result is analyzed from the viewpoint of the de Witt-Brehme-Hobbs equation (and corresponding equations in higher dimensions). The different frequency domains and their competition mentioned above, may be explained as coming from different terms in this equation. Thus the whole emission process may be naturally split in two sub-processes with drastically different spectral and temporal characteristics.

  7. An experimental test of the LPM effect: Bremsstrahlung suppression at high energies

    SciTech Connect

    Klein, S.; Cavalli-Sforza, M.; Kelley, L.; Anthony, P.; Dietrich, F.; Vanbibber, K.; Becker-Szendy, R.; Gearhart, R.; Niemi, G.; Perl, M.; Rochester, L.; Bosted, P.; Cowan, R.

    1992-11-01

    We are preparing an experiment at SLAC to test the LPM (Landau-Pomeranchuk-Migda) effect. In bremsstrahlung from high energy electrons, the longitudinal momentum transferred from the nucleus is very small. Then, by the uncertainty principle, the interaction must occur over a distance much larger than the atomic scale. In the LPM effect, multiple scattering changes the electron trajectory within the interaction distance, and so suppresses the bremsstrahlung. This effect, predicted in the 1950`s, has never been quantitatively studied. For dense, high Z, targets in a 25 GeV electron beam, suppression is significant for photons below a few hundred MeV. By comparing bremsstrahlung from targets of different (Pb, U, W and C), it is possible to measure the suppression accurately. We will also study the longitudinal density effect, where very low energy photon emission is suppressed due to the dielectric effect of the medium.

  8. An experimental test of the LPM effect: Bremsstrahlung suppression at high energies

    SciTech Connect

    Klein, S.; Cavalli-Sforza, M.; Kelley, L. . Inst. for Particle Physics); Anthony, P.; Dietrich, F.; Vanbibber, K. ); Becker-Szendy, R.; Gearhart, R.; Niemi, G.; Perl, M.; Rochester, L. ); Bosted, P. (American Univ., Washington, DC (United

    1992-11-01

    We are preparing an experiment at SLAC to test the LPM (Landau-Pomeranchuk-Migda) effect. In bremsstrahlung from high energy electrons, the longitudinal momentum transferred from the nucleus is very small. Then, by the uncertainty principle, the interaction must occur over a distance much larger than the atomic scale. In the LPM effect, multiple scattering changes the electron trajectory within the interaction distance, and so suppresses the bremsstrahlung. This effect, predicted in the 1950's, has never been quantitatively studied. For dense, high Z, targets in a 25 GeV electron beam, suppression is significant for photons below a few hundred MeV. By comparing bremsstrahlung from targets of different (Pb, U, W and C), it is possible to measure the suppression accurately. We will also study the longitudinal density effect, where very low energy photon emission is suppressed due to the dielectric effect of the medium.

  9. Lectures from the workshop on nucleon-nucleon bremsstrahlung, January 25--26, 1990

    SciTech Connect

    Gibson, B.F.; Schillaci, M.E.; Wender, S.A.

    1990-07-01

    The Nucleon-Nucleon Bremsstrahlung Workshop was convened at LAMPF on 25--26 January 1990 in order to review the theoretical and experimental aspects of that reaction with focus on a possible new initiative to measure neutron-proton bremsstrahlung using the intermediate-energy, white-spectrum neutron source at the LAMPF/WNR facility. Over the course of this intense day-and-a-half workshop, experts in the field established the historical perspective for both theory and experiment, presented result of recent calculations, and examined new approaches to the difficult neutron-proton bremsstrahlung experiment. Theoretical and experimental working groups generated recommendations for action and actually converged upon a plan for an experimental program, not just a single measurement.

  10. LPM Interference and Cherenkov-like Gluon Bremsstrahlung in DenseMatter

    SciTech Connect

    Majumder, Abhijit; Wang, Xin-Nian

    2005-07-26

    Gluon bremsstrahlung induced by multiple parton scattering in a finite dense medium has a unique angular distribution with respect to the initial parton direction. A dead-cone structure with an opening angle; theta2{sub 0}; approx 2(1-z)/(zLE) for gluons with fractional energy z arises from the Landau-Pomeran chuck-Migdal (LPM) interference. In a medium where the gluon's dielectric constant is; epsilon>1, the LPM interference pattern is shown to become Cherenkov-like with an increased opening angle determined by the dielectric constant$/cos2/theta{sub c}=z+(1-z)//epsilon$. For a large dielectric constant/epsilon; gg 1+2/z2LE, the corresponding total radiative parton energy loss is about twice that from normal gluon bremsstrahlung. Implications of this Cherenkov-like gluon bremsstrahlung to the jet correlation pattern in high-energy heavy-ion collisions is discussed.

  11. Impact of nucleon-nucleon bremsstrahlung rates beyond one-pion exchange

    NASA Astrophysics Data System (ADS)

    Bartl, A.; Bollig, R.; Janka, H.-T.; Schwenk, A.

    2016-10-01

    Neutrino-pair production and annihilation through nucleon-nucleon bremsstrahlung is included in current supernova simulations by rates that are based on the one-pion-exchange approximation. Here we explore the consequences of bremsstrahlung rates based on modern nuclear interactions for proto-neutron star cooling and the corresponding neutrino emission. We find that despite a reduction of the bremsstrahlung emission by a factor of 2-5 in the neutrinospheric region, models with the improved treatment exhibit only ≲5 % changes of the neutrino luminosities and an increase of ≲0.7 MeV of the average energies of the radiated neutrino spectra, with the largest effects for the antineutrinos of all flavors and at late times. Overall, the proto-neutron star cooling evolution is slowed down modestly by ≲0.5 - 1 s .

  12. 3D inpatient dose reconstruction from the PET-CT imaging of {sup 90}Y microspheres for metastatic cancer to the liver: Feasibility study

    SciTech Connect

    Fourkal, E.; Veltchev, I.; Lin, M.; Meyer, J.; Koren, S.; Doss, M.; Yu, J. Q.

    2013-08-15

    Purpose: The introduction of radioembolization with microspheres represents a significant step forward in the treatment of patients with metastatic disease to the liver. This technique uses semiempirical formulae based on body surface area or liver and target volumes to calculate the required total activity for a given patient. However, this treatment modality lacks extremely important information, which is the three-dimensional (3D) dose delivered by microspheres to different organs after their administration. The absence of this information dramatically limits the clinical efficacy of this modality, specifically the predictive power of the treatment. Therefore, the aim of this study is to develop a 3D dose calculation technique that is based on the PET imaging of the infused microspheres.Methods: The Fluka Monte Carlo code was used to calculate the voxel dose kernel for {sup 90}Y source with voxel size equal to that of the PET scan. The measured PET activity distribution was converted to total activity distribution for the subsequent convolution with the voxel dose kernel to obtain the 3D dose distribution. In addition, dose-volume histograms were generated to analyze the dose to the tumor and critical structures.Results: The 3D inpatient dose distribution can be reconstructed from the PET data of a patient scanned after the infusion of microspheres. A total of seven patients have been analyzed so far using the proposed reconstruction method. Four patients underwent treatment with SIR-Spheres for liver metastases from colorectal cancer and three patients were treated with Therasphere for hepatocellular cancer. A total of 14 target tumors were contoured on post-treatment PET-CT scans for dosimetric evaluation. Mean prescription activity was 1.7 GBq (range: 0.58–3.8 GBq). The resulting mean maximum measured dose to targets was 167 Gy (range: 71–311 Gy). Mean minimum dose to 70% of target (D70) was 68 Gy (range: 25–155 Gy). Mean minimum dose to 90% of target

  13. Patient doses from hybrid SPECT-CT procedures.

    PubMed

    Avramova-Cholakova, S; Dimcheva, M; Petrova, E; Garcheva, M; Dimitrova, M; Palashev, Y; Vassileva, J

    2015-07-01

    The aim of this work is to estimate patient doses from hybrid single-photon emission computed tomography (SPECT) and computed tomography (CT) procedures. The study involved all four SPECT-CT systems in Bulgaria. Effective dose was estimated for about 100 patients per system. Ten types of examinations were considered, representing all diagnostic procedures performed in the SPECT-CT systems. Effective doses from the SPECT component were calculated applying the ICRP 53 and ICRP 80 conversion coefficients. Computed tomography dose index and dose length product were retrospectively obtained from the archives of the systems, and effective doses from the CT component were calculated with CT-Expo software. Parallel estimation of CT component contribution with the National Radiological Protection Board (NRPB) conversion coefficients was performed where applicable. Large variations were found in the current practice of SPECT-CT imaging. Optimisation actions and diagnostic reference levels were proposed.

  14. Single photon emission computed tomography (SPECT) in epilepsy

    SciTech Connect

    Leroy, R.F.

    1991-12-31

    Epilepsy is a common neurologic disorder which has just begun to be studied with single photon emission computerized tomography (SPECT). Epilepsy usually is studied with electroencephalographic (EEG) techniques that demonstrate the physiologic changes that occur during seizures, and with neuroimaging techniques that show the brain structures where seizures originate. Neither method alone has been adequate to describe the pathophysiology of the patient with epilepsy. EEG techniques lack anatomic sensitivity, and there are no structural abnormalities shown by neuroimaging which are specific for epilepsy. Functional imaging (FI) has developed as a physiologic tool with anatomic sensitivity, and SPECT has been promoted as a FI technique because of its potentially wide availability. However, SPECT is early in its development and its clinical utility for epilepsy still has to be demonstrated. To understand this role of SPECT, consideration must be given to the pathophysiology of epilepsy, brain physiology, types of seizure, epileptic syndromes, and the SPECT technique itself. 44 refs., 2 tabs.

  15. Evaluation of bremsstrahlung contribution to photon transport in coupled photon-electron problems

    NASA Astrophysics Data System (ADS)

    Fernández, Jorge E.; Scot, Viviana; Di Giulio, Eugenio; Salvat, Francesc

    2015-11-01

    The most accurate description of the radiation field in x-ray spectrometry requires the modeling of coupled photon-electron transport. Compton scattering and the photoelectric effect actually produce electrons as secondary particles which contribute to the photon field through conversion mechanisms like bremsstrahlung (which produces a continuous photon energy spectrum) and inner-shell impact ionization (ISII) (which gives characteristic lines). The solution of the coupled problem is time consuming because the electrons interact continuously and therefore, the number of electron collisions to be considered is always very high. This complex problem is frequently simplified by neglecting the contributions of the secondary electrons. Recent works (Fernández et al., 2013; Fernández et al., 2014) have shown the possibility to include a separately computed coupled photon-electron contribution like ISII in a photon calculation for improving such a crude approximation while preserving the speed of the pure photon transport model. By means of a similar approach and the Monte Carlo code PENELOPE (coupled photon-electron Monte Carlo), the bremsstrahlung contribution is characterized in this work. The angular distribution of the photons due to bremsstrahlung can be safely considered as isotropic, with the point of emission located at the same place of the photon collision. A new photon kernel describing the bremsstrahlung contribution is introduced: it can be included in photon transport codes (deterministic or Monte Carlo) with a minimal effort. A data library to describe the energy dependence of the bremsstrahlung emission has been generated for all elements Z=1-92 in the energy range 1-150 keV. The bremsstrahlung energy distribution for an arbitrary energy is obtained by interpolating in the database. A comparison between a PENELOPE direct simulation and the interpolated distribution using the data base shows an almost perfect agreement. The use of the data base increases

  16. Measurement of gas bremsstrahlung from the insertion device beamlines of the advanced photon source

    SciTech Connect

    Pisharody, M.; Job, P.K.; Magill, S.

    1997-03-01

    High energy electron storage rings generate energetic bremsstrahlung photons through radiative interaction of the electrons (or positrons) with the residual gas molecules inside the storage ring. The resulting radiation exits at an average emittance angle of (m{sub 0}c{sub 2}/E) radian with respect to the electron beam path, where m{sub 0}c{sup 2} is the rest mass of E the electron and E its kinetic energy. Thus, at straight sections of the storage rings, moving electrons will produce a narrow and intense monodirectional photon beam. At synchrotron radiation facilities, where beamlines are channeled out of the storage ring, a continuous gas bremsstrahlung spectrum, with a maximum energy of the electron beam, will be present. There are a number of compelling reasons that a measurement of the bremsstrahlung characteristics be conducted at the Advanced Photon Source (APS) storage ring. Although the number of residual gas molecules present in the storage ring at typical nTorr vacuum is low, because of the long straight paths of the electrons in the storage ring at APS, significant production of bremsstrahlung will be produced. This may pose a radiation hazard. It is then imperative that personnel be shielded from dose rates due to this radiation. There are not many measurements available for gas bremsstrahlung, especially for higher electron beam energies. The quantitative estimates of gas bremsstrahlung from storage rings as evaluated by Monte Carlo codes also have several uncertainties. They are in general calculated for air at atmospheric pressure, the results of which are then extrapolated to typical storage ring vacuum values (of the order of 10{sup -9} Torr). Realistically, the actual pressure profile can vary inside the narrow vacuum chamber. Also, the actual chemical composition of the residual gas inside the storage ring is generally different from that of air.

  17. Bremsstrahlung radiation from slow electrons in a Coulomb field: Classical limit and quantum correction

    SciTech Connect

    Manakov, N. L. Krylovetsky, A. A.; Marmo, S. I.

    2015-11-15

    Compact analytic expressions have been derived by a direct expansion in ħ → 0 for the nonrelativistic amplitude of Coulomb bremsstrahlung radiation (BR), the differential (in frequency and angles of the scattered electron) BR cross section, and the triply differential BR cross section that takes into account the bremsstrahlung photon direction and polarization and the scattered electron direction. They contain the classical limit and a quantum correction of the order of ħ at an arbitrary BR frequency ω. An explicit expression has been found for the quantum correction of the order of ħ to the classical BR spectrum.

  18. Estimation of photoneutron yield from beryllium target irradiated by variable energy microtron-based bremsstrahlung radiation

    NASA Astrophysics Data System (ADS)

    Eshwarappa, K. M.; Ganesh; Siddappa, K.; Kashyap, Yogesh; Sinha, Amar; Sarkar, P. S.; Godwal, B. K.

    2005-03-01

    The possibility of setting up microtron-based photoneutron source by utilizing bremsstrahlung radiation interaction with beryllium targets is critically examined. The bremsstrahlung yield for tantalum (Ta) target is obtained by EGS4 simulation. The neutron yield is estimated theoretically by MCNP simulation. The yield was measured experimentally by neutron irradiation of calibrated SSNTD CR-39 films. The total neutron yield is found to be of the order 10 10 n/s for 250 Hz PRR and 10 9 n/s for 50 Hz PRR. A detailed comparison shows good agreement between theoretical and experimentally measured yields.

  19. Neutrino-pair bremsstrahlung from nucleon-α versus nucleon-nucleon scattering

    NASA Astrophysics Data System (ADS)

    Sharma, Rishi; Bacca, Sonia; Schwenk, A.

    2015-04-01

    We study the impact of the nucleon-α P -wave resonances on neutrino-pair bremsstrahlung. Because of the noncentral spin-orbit interaction, these resonances lead to an enhanced contribution to the nucleon spin structure factor for temperatures T ≲4 MeV. If the α -particle fraction is significant and the temperature is in this range, this contribution is competitive with neutron-neutron bremsstrahlung. This may be relevant for neutrino production in core-collapse supernovae or other dense astrophysical environments. Similar enhancements are expected for resonant noncentral nucleon-nucleus interactions.

  20. Myocardial Perfusion SPECT 2015 in Germany

    PubMed Central

    Burchert, Wolfgang; Schäfer, Wolfgang; Hacker, Marcus

    2016-01-01

    Summary Aim The working group Cardiovascular Nuclear Medicine of the German Society of Nuclear Medicine presents the results of the 7th survey of myocardial perfusion SPECT (MPS) of the reporting year 2015. Method 268 questionnaires (173 practices [PR], 67 hospitals [HO], 28 university hospitals [UH]) were evaluated. Results of the last survey from 2012 are set in squared brackets. Results MPS of 121 939 [105 941] patients were reported. 98 % [95 %] of all MPS were performed with Tc-99m radiopharmaceuticals and 2 % [5 %] with Tl-201. 78 % [79 %] of all patients were studied in PR, 14 % [15 %] in HO, and 8 % [6 %] in UH. A pharmacological stress test was performed in 43 % [39 %] (22 % [24 %] adenosine, 20 % [9 %] regadenoson, 1% [6 %] dipyridamole or dobutamine). Attenuation correction was applied in 25 % [2009: 10 %] of MPS. Gated SPECT was performed in 78 % [70 %] of all rest MPS, in 80 % [73 %] of all stress and in 76 % [67 %] of all stress and rest MPS. 53 % [33 %] of all nuclear medicine departments performed MPS scoring by default, whereas 24 % [41 %] did not apply any quantification. 31 % [26 %] of all departments noticed an increase in their counted MPS and 29 % [29 %] no changes. Data from 89 departments which participated in all surveys showed an increase in MPS count of 11.1 % (PR: 12.2 %, HO: 4.8 %, UH: 18.4 %). 70 % [60 %] of the MPS were requested by ambulatory care cardiologists. Conclusion The 2015 MPS survey reveals a high-grade adherence of routine MPS practice to current guidelines. The positive trend in MPS performance and number of MPS already observed in 2012 continues. Educational training remains necessary in the field of SPECT scoring. PMID:27909712

  1. Bayesian learning for cardiac SPECT image interpretation.

    PubMed

    Sacha, Jarosław P; Goodenday, Lucy S; Cios, Krzysztof J

    2002-01-01

    In this paper, we describe a system for automating the diagnosis of myocardial perfusion from single-photon emission computerized tomography (SPECT) images of male and female hearts. Initially we had several thousand of SPECT images, other clinical data and physician-interpreter's descriptions of the images. The images were divided into segments based on the Yale system. Each segment was described by the physician as showing one of the following conditions: normal perfusion, reversible perfusion defect, partially reversible perfusion defect, fixed perfusion defect, defect showing reverse redistribution, equivocal defect or artifact. The physician's diagnosis of overall left ventricular (LV) perfusion, based on the above descriptions, categorizes a study as showing one or more of eight possible conditions: normal, ischemia, infarct and ischemia, infarct, reverse redistribution, equivocal, artifact or LV dysfunction. Because of the complexity of the task, we decided to use the knowledge discovery approach, consisting of these steps: problem understanding, data understanding, data preparation, data mining, evaluating the discovered knowledge and its implementation. After going through the data preparation step, in which we constructed normal gender-specific models of the LV and image registration, we ended up with 728 patients for whom we had both SPECT images and corresponding diagnoses. Another major contribution of the paper is the data mining step, in which we used several new Bayesian learning classification methods. The approach we have taken, namely the six-step knowledge discovery process has proven to be very successful in this complex data mining task and as such the process can be extended to other medical data mining projects.

  2. Quantum diffraction and shielding effects on the low-energy electron-ion bremsstrahlung in two-component semiclassical plasmas

    SciTech Connect

    Lee, Myoung-Jae; Jung, Young-Dae

    2015-10-15

    The quantum diffraction and shielding effects on the low-energy bremsstrahlung process are investigated in two-component semiclassical plasmas. The impact-parameter analysis with the micropotential taking into account the quantum diffraction and shielding effects is employed to obtain the electron-ion bremsstrahlung radiation cross section as a function of the de Broglie wavelength, density parameter, impact parameter, photon energy, and projectile energy. The result shows that the influence of quantum diffraction and shielding strongly suppresses the bremsstrahlung radiation spectrum in semiclassical plasmas. It is found that the quantum diffraction and shielding effects have broaden the photon emission domain. It is also found that the photon emission domain is almost independent of the radiation photon energy. In addition, it is found that the influence of quantum diffraction and shielding on the bremsstrahlung spectrum decreases with an increase of the projectile energy. The density effect on the electron-ion bremsstrahlung cross section is also discussed.

  3. Monte Carlo Calculation of Radioimmunotherapy with 90Y-, 177Lu-, 131I-, 124I-, and 188Re-Nanoobjects: Choice of the Best Radionuclide for Solid Tumour Treatment by Using TCP and NTCP Concepts

    PubMed Central

    Lucas, S.; Feron, O.; Gallez, B.; Masereel, B.; Michiels, C.; Vander Borght, T.

    2015-01-01

    Radioimmunotherapy has shown that the use of monoclonal antibodies combined with a radioisotope like 131I or 90Y still remains ineffective for solid and radioresistant tumour treatment. Previous simulations have revealed that an increase in the number of 90Y labelled to each antibody or nanoobject could be a solution to improve treatment output. It now seems important to assess the treatment output and toxicity when radionuclides such as 90Y, 177Lu, 131I, 124I, and 188Re are used. Tumour control probability (TCP) and normal tissue complication probability (NTCP) curves versus the number of radionuclides per nanoobject were computed with MCNPX to evaluate treatment efficacy for solid tumours and to predict the incidence of surrounding side effects. Analyses were carried out for two solid tumour sizes of 0.5 and 1.0 cm radius and for nanoobject (i.e., a radiolabelled antibody) distributed uniformly or nonuniformly throughout a solid tumour (e.g., Non-small-cell-lung cancer (NSCLC)). 90Y and 188Re are the best candidates for solid tumour treatment when only one radionuclide is coupled to one carrier. Furthermore, regardless of the radionuclide properties, high values of TCP can be reached without toxicity if the number of radionuclides per nanoobject increases. PMID:26136812

  4. Monte Carlo Calculation of Radioimmunotherapy with (90)Y-, (177)Lu-, (131)I-, (124)I-, and (188)Re-Nanoobjects: Choice of the Best Radionuclide for Solid Tumour Treatment by Using TCP and NTCP Concepts.

    PubMed

    Lucas, S; Feron, O; Gallez, B; Masereel, B; Michiels, C; Vander Borght, T

    2015-01-01

    Radioimmunotherapy has shown that the use of monoclonal antibodies combined with a radioisotope like (131)I or (90)Y still remains ineffective for solid and radioresistant tumour treatment. Previous simulations have revealed that an increase in the number of (90)Y labelled to each antibody or nanoobject could be a solution to improve treatment output. It now seems important to assess the treatment output and toxicity when radionuclides such as (90)Y, (177)Lu, (131)I, (124)I, and (188)Re are used. Tumour control probability (TCP) and normal tissue complication probability (NTCP) curves versus the number of radionuclides per nanoobject were computed with MCNPX to evaluate treatment efficacy for solid tumours and to predict the incidence of surrounding side effects. Analyses were carried out for two solid tumour sizes of 0.5 and 1.0 cm radius and for nanoobject (i.e., a radiolabelled antibody) distributed uniformly or nonuniformly throughout a solid tumour (e.g., Non-small-cell-lung cancer (NSCLC)). (90)Y and (188)Re are the best candidates for solid tumour treatment when only one radionuclide is coupled to one carrier. Furthermore, regardless of the radionuclide properties, high values of TCP can be reached without toxicity if the number of radionuclides per nanoobject increases.

  5. Yttrium-90 (90Y) in the principal radionuclide therapies: an efficacy correlation between peptide receptor radionuclide therapy, radioimmunotherapy and transarterial radioembolization therapy. Ten years of experience (1999-2009).

    PubMed

    Goffredo, Veronica; Paradiso, Angelo; Ranieri, Girolamo; Gadaleta, Cosmo Damiano

    2011-12-01

    The clinical application of the pure beta emitter (90)Y constitutes a fundamental advancement in non-invasive medicine. Nowadays, mainly three oncological therapies exploit the intrinsic emissive characteristic of (90)Y. Radionuclide therapies include peptide receptor radionuclide therapy (PRRT) in neuroendocrine tumour (NET) treatment, radioimmunotherapy (RIT) in non-Hodgkin's lymphoma (NHL) treatment and transarterial radioembolization therapy (TARET) in unresectable hepatocellular carcinoma (HCC) and liver metastatic colorectal cancer (mCRC) treatment. The last ten years of clinical experience from E-PubMed research have been reviewed and an efficacy correlation between (90)Y-therapies has shown a better objective response rate for RIT (ORR 80±15%; range 53-100) compared to PRRT (ORR 23.5±14%; range 9-50), and TARET (ORR for mCRC, 40±25%; range 19-91, and ORR for HCC, 42±20%; range 20-82). This review reports on the state of the art of the efficacy of (90)Y-therapies from the last decade and discusses new perspectives of therapeutic development.

  6. Proceedings of clinical SPECT (single photon emission computed tomography) symposium

    SciTech Connect

    Not Available

    1986-09-01

    It has been five years since the last in-depth American College of Nuclear Physicians/Society of Nuclear Medicine Symposium on the subject of single photon emission computed tomography (SPECT) was held. Because this subject was nominated as the single most desired topic we have selected SPECT imaging as the basis for this year's program. The objectives of this symposium are to survey the progress of SPECT clinical applications that have taken place over the last five years and to provide practical and timely guidelines to users of SPECT so that this exciting imaging modality can be fully integrated into the evaluation of pathologic processes. The first half was devoted to a consideration of technical factors important in SPECT acquisition and the second half was devoted to those organ systems about which sufficient clinical SPECT imaging data are available. With respect to the technical aspect of the program we have selected the key areas which demand awareness and attention in order to make SPECT operational in clinical practice. These include selection of equipment, details of uniformity correction, utilization of phantoms for equipment acceptance and quality assurance, the major aspect of algorithms, an understanding of filtered back projection and appropriate choice of filters and an awareness of the most commonly generated artifacts and how to recognize them. With respect to the acquisition and interpretation of organ images, the faculty will present information on the major aspects of hepatic, brain, cardiac, skeletal, and immunologic imaging techniques. Individual papers are processed separately for the data base. (TEM)

  7. PET and SPECT studies in Parkinson's disease.

    PubMed

    Brooks, D J

    1997-04-01

    Positron emission tomography (PET) and single photon emission tomography (SPECT) provide sensitive means for quantifying the loss of nigrostriatal dopaminergic fibres in Parkinson's disease and for detecting the presence of dopaminergic dysfunction in asymptomatic at-risk relatives and patients with isolated tremor. Functional imaging can also be used to follow the rate of disease progression objectively, determine the efficacy of putative neuroprotective agents, and monitor the viability of transplants of fetal tissue. Additionally, in vivo pharmacological changes associated with development of treatment complications (fluctuations, dyskinesias) can be studied. Loss of dopaminergic projections produces profound changes in resting and activated brain metabolism. PET and SPECT activation studies have suggested that the akinesia of Parkinson's disease is associated with failure to activate the supplementary motor and dorsal pre-frontal areas. Activation of these cortical areas is restored towards normal by the use of dopaminergic medication, striatal transplantation with fetal mesencephalic tissue, and pallidotomy. The aim of this chapter is to review the insight which functional imaging has given us into the pathophysiology of parkinsonism.

  8. Quantitative SPECT of uptake of monoclonal antibodies

    SciTech Connect

    DeNardo, G.L.; Macey, D.J.; DeNardo, S.J.; Zhang, C.G.; Custer, T.R.

    1989-01-01

    Absolute quantitation of the distribution of radiolabeled antibodies is important to the efficient conduct of research with these agents and their ultimate use for imaging and treatment, but is formidable because of the unrestricted nature of their distribution within the patient. Planar imaging methods have been developed and provide an adequate approximation of the distribution of radionuclide for many purposes, particularly when there is considerable specificity of targeting. This is not currently the case for antibodies and is unlikely in the future. Single photon emission computed tomography (SPECT) provides potential for greater accuracy because it reduces problems caused by superimposition of tissues and non-target contributions to target counts. SPECT measurement of radionuclide content requires: (1) accurate determination of camera sensitivity; (2) accurate determination of the number of counts in a defined region of interest; (3) correction for attenuation; (4) correction for scatter and septal penetration; (5) accurate measurement of the administered dose; (6) adequate statistics; and (7) accurate definition of tissue mass or volume. The major impediment to each of these requirements is scatter of many types. The magnitude of this problem can be diminished by improvements in tomographic camera design, computer algorithms, and methodological approaches. 34 references.

  9. Experimental verification of bremsstrahlung production and dosimetry predictions for 15. 5 MeV electrons

    SciTech Connect

    Sanford, T.W.L.; Beutler, D.E.; Halbleib, J.A.; Knott, D.P.

    1991-01-01

    The radiation produced by a 15.5-MeV monoenergetic electron beam incident on optimized and nonoptimized bremsstrahlung targets is characterized using the ITS Monte Carlo code and measurements with equilibrated and non-equilibrated TLD dosimetry. Comparisons between calculations and measurements verify the calculations and demonstrate that the code can be used to predict both bremsstrahlung production and TLD response for radiation fields that are characteristic of those produced by pulsed simulators of gamma rays. At optimum bremsstrahlung production, the predicted total forward radiation fluence detected in equilibrated TLD dosimetry agrees with that measured within the {plus minus}6% uncertainty of the measurement. The absolute comparisons made here provide independent confirmation of the validity of the TLD calibration for photon fields characteristic of gamma-ray simulators. The empirical Martin equation, which is often used to calculate radiation dose from optimized bremsstrahlung targets, is examined, and its range of validity is established from the data presented. 23 refs., 11 figs., 2 tabs.

  10. Experimental verification of bremsstrahlung production and dosimetry predictions for 15. 5 MeV electrons

    SciTech Connect

    Sanford, T.W.L.; Beutler, D.E.; Halbleib, J.A. ); Knott, D.P. )

    1991-12-01

    In this paper the radiation produced by a 15.5-MeV mono-energetic electron beam incident on optimized and non-optimized bremsstrahlung targets is characterized using the ITS Monte Carlo code and measurements with equilibrated and non-equilibrated TLD dosimetry. Comparisons between calculations and measurements verify the calculations and demonstrate that the code can be used to predict both bremsstrahlung production and TLD response for radiation fields that are characteristic of those produced by pulsed simulators of gamma rays. At optimum bremsstrahlung production, the predicted total forward radiation fluence detected in equilibrated TLD dosimetry agrees with that measured with the {plus minus} 6% uncertainty of the measurement. The absolute comparisons made here provide independent confirmation of the validity of the TLD calibration for photon fields characteristic of gamma-ray simulators. The empirical Martin equation, which is often used to calculate radiation dose from optimized bremsstrahlung targets, is examined, and its range of validity is established from the data presented.

  11. Experimental verification of bremsstrahlung production and dosimetry predictions as a function of energy and angle

    SciTech Connect

    Beutler, D.E.; Halbleib, J.A.; Sanford, T.W.L. ); Knott, D.P. )

    1994-12-01

    The integrated TIGER series (ITS) of coupled electron/photon Monte Carlo transport codes is widely used to predict the radiation output from flash x-ray sources and for the design of bremsstrahlung converters. The codes are also used to predict the response of radiation diagnostics (e.g., thermoluminescent dosimeters (TLD's)) and the response of electronic components and subsystems. Hence, the demonstration of the validity of the ITS codes for these applications is important. Here, measurements of energy deposition from bremsstrahlung production as a function of angle and beam energy (5-25 MeV) are shown to be in excellent agreement with Monte Carlo predictions. Dosimetry measurements are made and predicted in both equilibrated and under equilibrated radiation environments. In the latter case the quality of the agreement requires an accurate prediction of both the photon and electron spectra produced by the primary electron beam. An improved empirical equation for predicting bremsstrahlung production is also presented. This empirical relation can be used to estimate doses without resorting to expensive calculational efforts. It also gives an analytical relationship for dose as a function of energy and angle for a converter optimized for bremsstrahlung production using 15.5 MeV electrons.

  12. Beta radiation shielding with lead and plastic: effect on bremsstrahlung radiation when switching the shielding order.

    PubMed

    Van Pelt, Wesley R; Drzyzga, Michael

    2007-02-01

    Lead and plastic are commonly used to shield beta radiation. Radiation protection literature is ubiquitous in advising the placement of plastic first to absorb all the beta particles before any lead shielding is used. This advice is based on the well established theory that radiative losses (bremsstrahlung production) are more prevalent in higher atomic number (Z) materials than in low Z materials. Using 32P beta radiation, we measured bremsstrahlung photons transmitted through lead and plastic (Lucite) shielding in different test configurations to determine the relative efficacy of lead alone, plastic alone, and the positional order of lead and plastic. With the source (32P) and detector held at a constant separation distance, we inserted lead and/or plastic absorbers and measured the reduction in bremsstrahlung radiation level measured by the detector. With these test conditions, analysis of measured bremsstrahlung radiation in various thicknesses and configurations of lead and plastic shielding shows the following: placing plastic first vs. lead first reduces the transmitted radiation level only marginally (10% to 40%); 2 mm of additional lead is sufficient to correct the "mistake" of placing the lead first; and for equal thicknesses or weights of lead and plastic, lead is a more efficient radiation shield than plastic.

  13. Nonlocality of radiative transfer in continuous spectra and Bremsstrahlung radiation transport in hot dense plasmas

    SciTech Connect

    Ivanov, V. V.; Kukushkin, A. B.

    1997-05-05

    The importance of nonlocal effects in radiative transfer in continuous spectra is shown in numerical modelling of space profiles of plasma temperature and Bremsstrahlung total power losses in a layer of adiabatically compressed hot dense plasma, via comparing the results of the exact, integral equation formalism and widely used approach of radiation temperature diffusion with Rosseland mean diffusion coefficient.

  14. SPECT-US image fusion and clinical applications

    NASA Astrophysics Data System (ADS)

    Hummel, Johann; Kaar, Marcus; Hoffmann, Rainer; Birkfellner, Wolfgang; Beyer, Thomas; Staudenherz, Anton; Figl, Michael

    2014-03-01

    Because scintigraphic images lack anatomical information, single photon emission tomography (SPECT) and positron emission tomography systems (PET) are combined physically with CTs to compensate for this drawback. In our work, we present a method where the CT is replaced by a 3D ultrasound device. Because in this case a mechanical linkage is not possible, we use an additional optical tracking system (OTS) for spatial correlation of the SPECT or PET information and the US. To enable image fusion between the functional SPECT and the anatomical US we first calibrate the SPECT by means of the optical tracking system. This is done by imaging a phantom with SPECT and scanning the surface of the phantom using a calibrated stylus of the OTS. Applying an iterative closest point (ICP) algorithm results in the transformation between the optical coordinate system and the SPECT coordinate system. When a patient undergoes a SPECT scan, a 3D US image is taken immediately after the scan. Since the scan head of the US is also tracked by the OTS, the transformation between OTS and SPECT can be calculated straight forward. For clinical intervention, the patient is again imaged with the US and a 3D/3D registration between the two US volumes allows to transform the functional information of the SPECT to the current US image in real time. We found a mean distance between the point cloud of the optical stylus and the segmented surface of the phantom of 2.3 mm while the maximum distance was found to be 6.9 mm. The 3D3D registration between the two US images was accomplished with an error of 2.1 mm.

  15. Fabrication of the pinhole aperture for AdaptiSPECT

    PubMed Central

    Kovalsky, Stephen; Kupinski, Matthew A.; Barrett, Harrison H.; Furenlid, Lars R.

    2015-01-01

    AdaptiSPECT is a pre-clinical pinhole SPECT imaging system under final construction at the Center for Gamma-Ray Imaging. The system is designed to be able to autonomously change its imaging configuration. The system comprises 16 detectors mounted on translational stages to move radially away and towards the center of the field-of-view. The system also possesses an adaptive pinhole aperture with multiple collimator diameters and pinhole sizes, as well as the possibility to switch between multiplexed and non-multiplexed imaging configurations. In this paper, we describe the fabrication of the AdaptiSPECT pinhole aperture and its controllers. PMID:26146443

  16. The use of gel dosimetry to measure the 3D dose distribution of a 90Sr/90Y intravascular brachytherapy seed.

    PubMed

    Massillon-Jl, G; Minniti, R; Mitch, M G; Maryanski, M J; Soares, C G

    2009-03-21

    Absorbed dose distributions in 3D imparted by a single (90)Sr/(90)Y beta particle seed source of the type used for intravascular brachytherapy were investigated. A polymer gel dosimetry medium was used as a dosemeter and phantom, while a special high-resolution laser CT scanner with a spatial resolution of 100 microm in all dimensions was used to quantify the data. We have measured the radial dose function, g(L)(r), observing that g(L)(r) increases to a maximum value and then decreases as the distance from the seed increases. This is in good agreement with previous data obtained with radiochromic film and thermoluminescent dosemeters (TLDs), even if the TLDs underestimate the dose at distances very close to the seed. Contrary to the measurements, g(L)(r) calculated through Monte Carlo simulations and reported previously steadily decreases without a local maximum as a function of the distance from the seed. At distances less than 1.5 mm, differences of more than 20% are observed between the measurements and the Monte Carlo calculations. This difference could be due to a possible underestimation of the energy absorbed into the seed core and encapsulation in the Monte Carlo simulation, as a consequence of the unknown precise chemical composition of the core and its respective density for this seed. The results suggest that g(L)(r) can be measured very close to the seed with a relative uncertainty of about 1% to 2%. The dose distribution is isotropic only at distances greater than or equal to 2 mm from the seed and is almost symmetric, independent of the depth. This study indicates that polymer gel coupled with the special small format laser CT scanner are valid and accurate methods for measuring the dose distribution at distances close to an intravascular brachytherapy seed.

  17. Influence of cations on the complexation yield of DOTATATE with yttrium and lutetium: a perspective study for enhancing the 90Y and 177Lu labeling conditions.

    PubMed

    Asti, Mattia; Tegoni, Matteo; Farioli, Daniela; Iori, Michele; Guidotti, Claudio; Cutler, Cathy S; Mayer, Pat; Versari, Annibale; Salvo, Diana

    2012-05-01

    The DOTA macrocyclic ligand can form stable complexes with many cations besides yttrium and lutetium. For this reason, the presence of competing cationic metals in yttrium-90 and lutetium-177 chloride solutions can dramatically influence the radiolabeling yield. The aim of this study was to evaluate the coordination yield of yttrium- and lutetium-DOTATATE complexes when the reaction is performed in the presence of varying amounts of competing cationic impurities. In the first set of experiments, the preparation of the samples was performed by using natural yttrium and lutetium (20.4 nmol). The molar ratio between DOTATATE and these metals was 1 to 1. Metal competitors (Pb(2+), Zn(2+), Cu(2+), Fe(3+), Al(3+), Ni(2+), Co(2+), Cr(3+)) were added separately to obtain samples with varying molar ratio with respect to yttrium or lutetium (0.1, 0.5, 1, 2 and 10). The final solutions were analyzed through ultra high-performance liquid chromatography with an UV detector. In the second set of experiments, an amount of (90)Y or (177)Lu chloride (6 MBq corresponding to 3.3 and 45 pmol, respectively) was added to the samples, and a radio-thin layer chromatography analysis was carried out. The coordination of Y(3+) and Lu(3+) was dramatically influenced by low levels of Zn(2+), Cu(2+) and Co(2+). Pb(2+) and Ni(2+) were also shown to be strong competitors at higher concentrations. Fe(3+) was expected to be a strong competitor, but the effect on the incorporation was only partly dependent on its concentration. Al(3+) and Cr(3+) did not compete with Y(3+) and Lu(3+) in the formation of DOTATATE complexes.

  18. Late and very late catch-up after 90Sr/90Y beta-irradiation for the treatment of coronary in-stent restenosis.

    PubMed

    Schiele, Thomas M; Herbst, Jan; Pöllinger, Barbara; Rieber, Johannes; König, Andreas; Sohn, Hae-Young; Krötz, Florian; Leibig, Marcus; Belka, Claus; Klauss, Volker

    2011-03-01

    Since late vessel failure has been speculated as a significant limitation of vascular brachytherapy (VBT), we conducted a prospective clinical evaluation at 6, 12, 24, 36 and 60 months follow-up after irradiation with (90)Sr/(90)Y for in-stent restenosis (ISR) regardless of the patient's symptomatic status. Complete five-year follow-up is reported for 104 consecutive patients. The cumulative rate of death was 13.5% (6 months: 0.96%; 12 months: 2.88%; 24 months: 4.81%; 36 months: 7.69%), of acute myocardial infarction 4.81% (2.88%; 4.81%; 4.81%; 4.81%), of late thrombotic occlusion 4.81% (3.85%; 4.81%; 4.81%; 4.81%), of target lesion revascularization (TLR) 27.9% (8.65%; 12.5%; 17.3%; 21.2%), of target vessel revascularization (TVR) 43.3% (12.5%; 19.2%; 22.1%; 29.8%), and of all major adverse cardiovascular events (MACE) 61.5% (16.3%; 26.9%; 31.7%; 42.3%), respectively. Considered that the annual incidence of TVR after the first year following drug-eluting stenting for in-stent restenosis has been reported as approximately 3% per year, an incidence of 5.8% per year following VBT of our study population clearly indicates a more pronounced, delayed and, even in the fifth year after the index procedure, ongoing restenotic process following beta-irradiation of in-stent restenotic lesions associated with clinically relevant adverse cardiovascular events.

  19. High-power, photofission-inducing bremsstrahlung source for intense pulsed active detection of fissile material

    NASA Astrophysics Data System (ADS)

    Zier, J. C.; Mosher, D.; Allen, R. J.; Commisso, R. J.; Cooperstein, G.; Hinshelwood, D. D.; Jackson, S. L.; Murphy, D. P.; Ottinger, P. F.; Richardson, A. S.; Schumer, J. W.; Swanekamp, S. B.; Weber, B. V.

    2014-06-01

    Intense pulsed active detection (IPAD) is a promising technique for detecting fissile material to prevent the proliferation of special nuclear materials. With IPAD, fissions are induced in a brief, intense radiation burst and the resulting gamma ray or neutron signals are acquired during a short period of elevated signal-to-noise ratio. The 8 MV, 200 kA Mercury pulsed-power generator at the Naval Research Laboratory coupled to a high-power vacuum diode produces an intense 30 ns bremsstrahlung beam to study this approach. The work presented here reports on Mercury experiments designed to maximize the photofission yield in a depleted-uranium (DU) object in the bremsstrahlung far field by varying the anode-cathode (AK) diode gap spacing and by adding an inner-diameter-reducing insert in the outer conductor wall. An extensive suite of diagnostics was fielded to measure the bremsstrahlung beam and DU fission yield as functions of diode geometry. Delayed fission neutrons from the DU proved to be a valuable diagnostic for measuring bremsstrahlung photons above 5 MeV. The measurements are in broad agreement with particle-in-cell and Monte Carlo simulations of electron dynamics and radiation transport. These show that with increasing AK gap, electron losses to the insert and outer conductor wall increase and that the electron angles impacting the bremsstrahlung converter approach normal incidence. The diode conditions for maximum fission yield occur when the gap is large enough to produce electron angles close to normal, yet small enough to limit electron losses.

  20. Design and development of MR-compatible SPECT systems for simultaneous SPECT-MR imaging of small animals

    NASA Astrophysics Data System (ADS)

    Tsui, Benjamin M. W.; Hugg, James W.; Xu, Jingyan; Chen, Si; Meier, Dirk; Edelstein, William; El-Sharkawy, Abdel; Wagenaar, Douglas J.; Patt, Bradley E.

    2011-03-01

    We describe a continuing design and development of MR-compatible SPECT systems for simultaneous SPECT-MR imaging of small animals. A first generation prototype SPECT system was designed and constructed to fit inside a MRI system with a gradient bore inner diameter of 12 cm. It consists of 3 angularly offset rings of 8 detectors (1"x1", 16x16 pixels MR-compatible solid-state CZT). A matching 24-pinhole collimator sleeve, made of a tungsten-compound, provides projections from a common FOV of ~25 mm. A birdcage RF coil for MRI data acquisition surrounds the collimator. The SPECT system was tested inside a clinical 3T MRI system. Minimal interference was observed on the simultaneously acquired SPECT and MR images. We developed a sparse-view image reconstruction method based on accurate modeling of the point response function (PRF) of each of the 24 pinholes to provide artifact-free SPECT images. The stationary SPECT system provides relatively low resolution of 3-5 mm but high geometric efficiency of 0.5- 1.2% for fast dynamic acquisition, demonstrated in a SPECT renal kinetics study using Tc-99m DTPA. Based on these results, a second generation prototype MR-compatible SPECT system with an outer diameter of 20 cm that fits inside a mid-sized preclinical MRI system is being developed. It consists of 5 rings of 19 CZT detectors. The larger ring diameter allows the use of optimized multi-pinhole collimator designs, such as high system resolution up to ~1 mm, high geometric efficiency, or lower system resolution without collimator rotation. The anticipated performance of the new system is supported by simulation data.

  1. Performance evaluation of advanced industrial SPECT system with diverging collimator.

    PubMed

    Park, Jang Guen; Jung, Sung-Hee; Kim, Jong Bum; Moon, Jinho; Yeom, Yeon Soo; Kim, Chan Hyeong

    2014-12-01

    An advanced industrial SPECT system with 12-fold-array diverging collimator was developed for flow visualization in industrial reactors and was discussed in the previous study. The present paper describes performance evaluation of the SPECT system under both static- and dynamic- flow conditions. Under static conditions, the movement of radiotracer inside the test reactor was compared with that of color tracer (blue ink) captured with a high-speed camera. The comparison of the reconstructed images obtained with the radiotracer and the SPECT system showed fairly good agreement with video-frames of the color tracer obtained with the camera. Based on the results of the performance evaluation, it is concluded that the SPECT system is suitable for investigation and visualization of flows in industrial flow reactors.

  2. [The development and application in clinical programme of SPECT].

    PubMed

    Sun, Li-ming; Liu, Chen-bin

    2002-11-01

    On the base of original computer software of Elscint Apex 609 RG SPECT, two clinical application programmes are successfully designed for clinical engineers to explore and practise by using the CLIP (The Clinical Interpreter Programming) language.

  3. Initial Investigation of Preclinical Integrated SPECT and MR Imaging

    PubMed Central

    Hamamura, Mark J.; Ha, Seunghoon; Roeck, Werner W.; Wagenaar, Douglas J.; Meier, Dirk; Patt, Bradley E.; Nalcioglu, Orhan

    2014-01-01

    Single-photon emission computed tomography (SPECT) can provide specific functional information while magnetic resonance imaging (MRI) can provide high-spatial resolution anatomical information as well as complementary functional information. In this study, we utilized a dual modality SPECT/MRI (MRSPECT) system to investigate the integration of SPECT and MRI for improved image accuracy. The MRSPECT system consisted of a cadmium-zinc-telluride (CZT) nuclear radiation detector interfaced with a specialized radiofrequency (RF) coil that was placed within a whole-body 4 T MRI system. The importance of proper corrections for non-uniform detector sensitivity and Lorentz force effects was demonstrated. MRI data were utilized for attenuation correction (AC) of the nuclear projection data and optimized Wiener filtering of the SPECT reconstruction for improved image accuracy. Finally, simultaneous dual-imaging of a nude mouse was performed to demonstrated the utility of co-registration for accurate localization of a radioactive source. PMID:20082527

  4. Cervical SPECT Camera for Parathyroid Imaging

    SciTech Connect

    None, None

    2012-08-31

    Primary hyperparathyroidism characterized by one or more enlarged parathyroid glands has become one of the most common endocrine diseases in the world affecting about 1 per 1000 in the United States. Standard treatment is highly invasive exploratory neck surgery called Parathyroidectomy. The surgery has a notable mortality rate because of the close proximity to vital structures. The move to minimally invasive parathyroidectomy is hampered by the lack of high resolution pre-surgical imaging techniques that can accurately localize the parathyroid with respect to surrounding structures. We propose to develop a dedicated ultra-high resolution (~ 1 mm) and high sensitivity (10x conventional camera) cervical scintigraphic imaging device. It will be based on a multiple pinhole-camera SPECT system comprising a novel solid state CZT detector that offers the required performance. The overall system will be configured to fit around the neck and comfortably image a patient.

  5. ACR testing of a dedicated head SPECT unit.

    PubMed

    Sensakovic, William F; Hough, Matthew C; Kimbley, Elizabeth A

    2014-07-08

    Physics testing necessary for program accreditation is rigorously defined by the ACR. This testing is easily applied to most conventional SPECT systems based on gamma camera technology. The inSPira HD is a dedicated head SPECT system based on a rotating dual clamshell design that acquires data in a dual-spiral geometry. The unique geometry and configuration force alterations of the standard ACR physics testing protocol. Various tests, such as intrinsic planar uniformity and/or resolution, do not apply. The Data Spectrum Deluxe Phantom used for conventional SPECT testing cannot fit in the inSPira HD scanner bore, making (currently) unapproved use of the Small Deluxe SPECT Phantom necessary. Matrix size, collimator type, scanning time, reconstruction method, and attenuation correction were all varied from the typically prescribed ACR instructions. Visible spheres, sphere contrast, visible rod groups, uniformity, and root mean square (RMS) noise were measured. The acquired SPECT images surpassed the minimum ACR requirements for both spatial resolution (9.5 mm spheres resolved) and contrast (6.4 mm rod groups resolved). Sphere contrast was generally high. Integral uniformity was 4% and RMS noise was 1.7%. Noise appeared more correlated than in images from a conventional SPECT scanner. Attenuation-corrected images produced from direct CT scanning of the phantom and a manufacturer supplied model of the phantom demonstrated negligible differences.

  6. Review and current status of SPECT scatter correction

    NASA Astrophysics Data System (ADS)

    Hutton, Brian F.; Buvat, Irène; Beekman, Freek J.

    2011-07-01

    Detection of scattered gamma quanta degrades image contrast and quantitative accuracy of single-photon emission computed tomography (SPECT) imaging. This paper reviews methods to characterize and model scatter in SPECT and correct for its image degrading effects, both for clinical and small animal SPECT. Traditionally scatter correction methods were limited in accuracy, noise properties and/or generality and were not very widely applied. For small animal SPECT, these approximate methods of correction are often sufficient since the fraction of detected scattered photons is small. This contrasts with patient imaging where better accuracy can lead to significant improvement of image quality. As a result, over the last two decades, several new and improved scatter correction methods have been developed, although often at the cost of increased complexity and computation time. In concert with (i) the increasing number of energy windows on modern SPECT systems and (ii) excellent attenuation maps provided in SPECT/CT, some of these methods give new opportunities to remove degrading effects of scatter in both standard and complex situations and therefore are a gateway to highly quantitative single- and multi-tracer molecular imaging with improved noise properties. Widespread implementation of such scatter correction methods, however, still requires significant effort.

  7. Laser-intensity requirements for generating enhanced kilovolt bremsstrahlung emission in intense laser-cluster interactions

    NASA Astrophysics Data System (ADS)

    Whitney, K. G.; Davis, J.; Petrova, Tz. B.; Petrov, G. M.

    2012-06-01

    The effects of ultrahigh-intensity laser radiation on dynamical processes such as electron scattering, bremsstrahlung emission, and pair production, have received growing theoretical interest as laser intensities in the laboratory continue to increase. Recently, for example, a calculation was published that predicted resonant increases of more than four orders of magnitude in bremsstrahlung emission in the presence of intense optical laser radiation [A. A. Lebed and S. P. Roshchupkin, Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.81.033413 81, 033413 (2010)]. The analysis in that paper was limited to laser intensities of ≤1017 W/cm2, and it was applied only to bremsstrahlung emissions at the laser frequency. In the present paper, we extend this Lebed and Roshchupkin analysis in order to assess the possibility of achieving some enhancement in bremsstrahlung emissions at significantly higher harmonics of the optical laser photon energies (˜6 keV) and thereby to appraise whether or not enhanced bremsstrahlung emissions may have played a hidden role in producing the population inversions and kilovolt x-ray amplifications that have been seen experimentally [A. B. Borisov , J. Phys. B 40, F307 (2007)]. In those experiments, light from a KrF laser was focused onto a gas of xenon clusters to intensities ≳1019 W/cm2. A model of the expansion and ionization dynamics of a xenon cluster when heated by such laser intensities has been constructed [Tz. B. Petrova , High Energy Density Phys.1574-181810.1016/j.hedp.2012.03.007 8, 209 (2012)]. It is capable of replicating the x-ray gains seen experimentally, but only under the assumption that sufficiently high inner-shell photoionization rates are generated in the experiments. We apply this model to show that such photoionization rates are achievable, but only if there are enhancements of the Bethe-Heitler bremsstrahlung emission rate of three to four orders of magnitude. Our extended analysis of the Lebed and Roshchupkin work

  8. Complementary approaches for the evaluation of biocompatibility of 90Y-labeled superparamagnetic citric acid (Fe,Er)3O4 coated nanoparticles

    DOE PAGES

    Antic, Bratislav; Boskovic, Marko; Nikodinovic-Runic, Jasmina; ...

    2017-02-10

    Magnetic nanoparticles (MNPs) are of immense interest for diagnostic and therapeutic applications in medicine. Design and development of new iron oxide-based MNPs for such applications is of rather limited breadth without reliable and sensitive methods to determine their levels in body tissues. Commonly used methods, such as ICP, are quite problematic, due to the inability to decipher the origin of the detected iron, i.e. whether it originates from the MNPs or endogenous from tissues and bodily fluids. One of the approaches to overcome this problem and to increase reliability of tracing MNPs is to partially substitute iron ions in themore » MNPs with Er. Here, we report on the development of citric acid coated (Fe,Er)3O4 nanoparticles and characterization of their physico-chemical and biological properties by utilization of various complementary approaches. The synthesized MNPs had a narrow (6–7 nm) size distribution, as consistently seen in atomic pair distribution function, transmission electron microscopy, and DC magnetization measurements. The particles were found to be superparamagnetic, with a pronounced maximum in measured zero-field cooled magnetization at around 90 K. Reduction in saturation magnetization due to incorporation of 1.7% Er3+ into the Fe3O4 matrix was clearly observed. From the biological standpoint, citric acid coated (Fe,Er)3O4 NPs were found to induce low toxicity both in human cell fibroblasts and in zebrafish (Danio rerio) embryos. Biodistribution pattern of the MNPs after intravenous administration in healthy Wistar rats was followed by the radiotracer method, revealing that 90Y-labeled MNPs were predominantly found in liver (75.33% ID), followed by lungs (16.70% ID) and spleen (2.83% ID). Quantitative agreement with these observations was obtained by ICP-MS elemental analysis using Er as the detected tracer. Based on the favorable physical, chemical and biological characteristics, citric acid coated (Fe,Er)3O4 MNPs could be further

  9. Investigation of a {sup 90}Sr/{sup 90}Y source for intra-ocular treatment of wet age-related macular degeneration

    SciTech Connect

    Holmes, Shannon M.; Micka, John A.; DeWerd, Larry A.

    2009-10-15

    Purpose: The purpose of this study is to perform an extensive investigation of an approximately 2.5 mm long {sup 90}Sr/{sup 90}Y source designed for treating wet age-related macular degeneration. Methods: As part of this investigation, a NIST-traceable absorbed dose to water calibration technique was established, and a source deployment verification test was developed. The influence of treatment cannula construction tolerance on the measurements as well as the dose delivered to the patient was investigated using the Monte Carlo code MCNP5. Variation between production cannulae was quantified experimentally using a well-type ionization chamber, and additional measurements along with Monte Carlo calculations of the collimating insert used for source deployment verification were performed to validate the model. Results: Maximum variation in the integrated target dose was seen when the source was shifted laterally within the treatment cannula. For the well chamber measurements, the observed standard deviation in ionization current for a single source placed in different reference cannulae was {+-}0.3%, with a maximum observed range of less than {+-}0.5%. Clinical cannulae in the collimating insert showed an average of 17.8%{+-}0.4% of the reference signal when sources were fully deployed compared to 18.5% predicted by Monte Carlo calculations. This discrepancy has been attributed primarily to construction of the collimator since the collimation gap was observed to be approximately 0.025-0.075 mm smaller than specified. Construction tolerance of the well chamber insert as well as position tolerance of the cannula tip were both investigated, and their influence on the predicted signal was quantified. Additional measurements along with Monte Carlo based calculations of the collimating insert with polyethylene spacers added to the setup were performed to validate the Monte Carlo model. The shimmed Monte Carlo and measured data agree to within 1%, which is a magnitude

  10. Electron-atom bremsstrahlung: Double-differential cross section and polarization correlations

    NASA Astrophysics Data System (ADS)

    Yerokhin, Vladimir A.; Surzhykov, Andrey

    2010-12-01

    The leading-order electron-atom bremsstrahlung is investigated within the rigorous relativistic approach based on the partial-wave representation of the Dirac wave functions in the external atomic field. Approximating the atomic target by an effective local potential, we calculate the double-differential cross section and the polarization correlations in a wide range of the impact energies. Connection between the bremsstrahlung at the hard-photon end point of the spectrum and the continuum-threshold limit of the radiative recombination is studied. A detailed analysis of the screening effect and the energy dependence of the polarization correlations is presented, with the main focus on the high-impact-energy region.

  11. Determination of the temperature of bremsstrahlung photon generated by ultraintense laser using various thickness attenuators

    SciTech Connect

    Hasegawa, Shuichi; Takashima, Ryuta; Todoriki, Masaru; Kikkawa, Satoshi; Soda, Keita; Takano, Kei; Oishi, Yuji; Nayuki, Takuya; Fujii, Takashi; Nemoto, Koshichi

    2011-03-15

    We evaluate the simplified method using the Lambert-Beer law to measure the temperature of bremsstrahlung photon generated by an ultraintense laser. Analytical values are compared to the results of the Monte Carlo calculation of GEANT4 and they agreed very well on the condition of the appropriate distance between the attenuator and the detector. We performed the experiment to measure the temperature of bremsstrahlung x-ray emitted from a metal target irradiated by a Ti:sapphire laser with 76 mJ, 72 fs, 2.2 x 10{sup 18} W/cm{sup 2}. For a Cu target of 30 {mu}m thick, the photon temperature was reasonably determined to be 0.18 MeV, which is in good agreement with previous studies.

  12. Experimental verification of dosimetry predictions of bremsstrahlung attenuation as a function of material and electron energy

    SciTech Connect

    Sanford, T.W.L.; Halbleib, J.A.; Beutler, D.E. ); Knott, D.P. )

    1993-12-01

    Dose attenuation with depth in an absorber of on-axis bremsstrahlung generated from an electron target is measured and shown to agree within [+-]9% with Monte Carlo predictions as a function of absorber material (Al,Fe,Pb) and incident electron beam energy (5.5-25.1 MeV). For this on-axis bremsstrahlung, 1 to 5 g/cm[sup 2] of upstream and 0.2 to 1 g/cm[sup 2] of downstream Al buffer is sufficient to provide electron equilibration for CaF[sub 2]:Mn thermoluminescent dosimeters (TI-Ds) over the measured energy range of 5.5 to 25.1 MeV, respectively. Once effective'' equilibration has been established, an expression of the form DA/Q = C[sub 1]V[sup C[sub 2

  13. Experimental verification of dosimetry predictions of bremsstrahlung attenuation as a function of material and electron energy

    SciTech Connect

    Sanford, T.W.L.; Halbleib, J.A.; Beutler, D.E. ); Knott, D.P. )

    1993-01-01

    Dose attenuation with depth in an absorber of on-axis bremsstrahlung generated from an electron target is measured and shown to agree within [plus minus]9% with Monte Carlo predictions as a function of absorber material (Al, Fe, Pb) and incident electron-beam energy (5.5--25.1 MeV). For this on-axis bremsstrahlung, 1 to 5 g/cm[sup 2] of upstream and 0.2 to 1 g/cm[sup 2] of downs Al buffer is sufficient to provide electron equilibration for CaF[sub 2]:Mn thermoluminescent dosimeter (TLDs) over the measured energy range of 5.5 to 25.1 MeV, respectively. Once effective'' equilibration has been established, an expression of the form DA/Q = C[sub 1]V[sup c[sub 2

  14. Electron accelerator-based production of molybdenum-99: Bremsstrahlung and photoneutron generation from molybdenum vs. tungsten

    NASA Astrophysics Data System (ADS)

    Tsechanski, A.; Bielajew, A. F.; Archambault, J. P.; Mainegra-Hing, E.

    2016-01-01

    A new "one-stage" approach for production of 99Mo and other radioisotopes by means of an electron linear accelerator is described. It is based on using a molybdenum target both as a bremsstrahlung converter and as a radioisotope producing target for the production of 99Mo via the photoneutron reaction 100Mo(γ,n)99Mo. Bremsstrahlung characteristics, such as bremsstrahlung efficiency, angular distribution, and energy deposition for molybdenum targets were obtained by means of the EGSnrc Monte Carlo simulation code system. As a result of our simulations, it is concluded that a 60 MeV electron beam incident on a thick Mo target will have greater bremsstrahlung efficiency than the same thickness (in units of r0) W target, for target thickness z > 1.84r0, where r0 is the electron range. A 50 MeV electron beam incident on a Mo target will result in greater bremsstrahlung efficiency than the same thickness W target (in units of r0) for target thickness case: z ⩾ 2.0r0. It is shown for the one-stage approach with thicknesses of (1.84-2.0)r0, that the 99Mo-production bremsstrahlung efficiency of a molybdenum target is greater by ∼100% at 30 MeV and by ∼70% at 60 MeV compared to the values for tungsten of the same thickness (in units of the appropriate r0) in the traditional two-stage approach (W converter and separate 99Mo producing target). This advantage of the one-stage approach arises from the fact that the bremsstrahlung produced is attenuated only once from attenuation in the molybdenum converter/target. In the traditional, two-stage approach, the bremsstrahlung generated in the W-converter/target is attenuated both in the converter in the 99Mo-producing molybdenum target. The photoneutron production yield of molybdenum and tantalum (as a substitute for tungsten) target was calculated by means of the MCNP5 transport code. On the basis of these data, the specific activity for the one-stage approach of three enriched 100Mo-targets of a 2 cm diameter and

  15. Analytic limits on the forms of spectra possible from optically thin collisional bremsstrahlung source models

    NASA Technical Reports Server (NTRS)

    Brown, John C.; Emslie, A. Gordon

    1988-01-01

    The constraints on hard X-ray bremsstrahlung spectral forms required in order for them to correspond to physically acceptable (nonnegative) electron distributions in thin-target, thick-target, and thermal source models are discussed. The extent to which various spectra can be attributed to the different models is examined, showing that many possible spectra cannot be described by all, or in some cases, any of the models. It is shown that for any bremsstrahlung cross section, the thick-target and thermal models require that successively higher derivatives of the thin-target constraint have the appropriate sign. It is found that thermal models are the most restrictive, and that thin-target models are the least restrictive. Explicit analytic constraint expressions are derived for all three cases for the Kramers cross section and examples of acceptable and unacceptable spectra are given. Application of these criteria to the testing and exclusion of models is discussed.

  16. An Investigation of Bremsstrahlung Reflection in a Dense Plasma Focus (DPF) Propulsion Device

    SciTech Connect

    Thomas, Robert; Miley, G. H.; Mead, Franklin

    2006-01-20

    The dense plasma focus device is one of the few fusion systems that is capable of burning advanced fuels such as D - 3He and p - 11B. An study has been performed and shown that three main requirements must be satisfied to reach breakeven for DPF fusion: a high Ti/Te ration ({approx} 20), an order of magnitude higher pinch lifetime, and the reflection and absorption if at least 50% Bremsstrahlung radiation. The latter issue is the focus of this report, and a literature search has been performed on laser-driven fusion radiation cavities, multilayer reflectors, and their application to Bremsstrahlung radiation reflection is presented. Additionally, the results found are compared to those assumed in the earlier DPF study bring p-11B.

  17. Diagnostic role of (99)Tc(m)-MDP SPECT/CT combined SPECT/MRI Multi modality imaging for early and atypical bone metastases.

    PubMed

    Chen, Xiao-Liang; Li, Qian; Cao, Lin; Jiang, Shi-Xi

    2014-01-01

    The bone metastasis appeared early before the bone imaging for most of the above patients. (99)Tc(m)-MDP ((99)Tc(m) marked methylene diphosphonate) bone imaging could diagnosis the bone metastasis with highly sensitivity, but with lower specificity. The aim of this study is to explore the diagnostic value of (99)Tc(m)-MDP SPECT/CT combined SPECT/MRI Multi modality imaging for the early period atypical bone metastases. 15 to 30 mCi (99)Tc(m)-MDP was intravenously injected to the 34 malignant patients diagnosed as doubtful early bone metastases. SPECT, CT and SPECT/CT images were captured and analyzed consequently. For the patients diagnosed as early period atypical bone metastases by SPECT/CT, combining the SPECT/CT and MRI together as the SPECT/MRI integrated image. The obtained SPECT/MRI image was analyzed and compared with the pathogenic results of patients. The results indicated that 34 early period doubtful metastatic focus, including 34 SPECT positive focus, 17 focus without special changes by using CT method, 11 bone metastases focus by using SPECT/CT method, 23 doubtful bone metastases focus, 8 doubtful bone metastases focus, 14 doubtful bone metastases focus and 2 focus without clear image. Totally, SPECT/CT combined with SPECT/MRI method diagnosed 30 bone metastatic focus and 4 doubtfully metastatic focus. In conclusion, (99)Tc(m)-MDP SPECT/CT combined SPECT/MRI Multi modality imaging shows a higher diagnostic value for the early period bone metastases, which also enhances the diagnostic accuracy rate.

  18. Nuclear effects on axions emission rates from nucleon-nucleon bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Pastrav, B.; Scafes, A. C.

    2010-11-01

    The rates of axion emissions by nucleon-nucleon bremsstrahlung from neutron stars obtained with the inclusion of the full angular momentum contribution from a nuclear one-pion-exchange potential (OPEP), are studied in different conditions of temperature and degeneracy in both, non degenerate (ND) and degenerate (D) regimes. The comparison with the previous results obtained in literature, where only the high momentum limit of the OPEP expressions are used, is done and the differences discussed.

  19. Radial scanning diagnostics of bremsstrahlung and line emission in T-10 plasma

    NASA Astrophysics Data System (ADS)

    Nemets, A. R.; Krupin, V. A.; Klyuchnikov, L. A.; Korobov, K. V.; Nurgaliev, M. R.

    2016-12-01

    The paper describes the scanning spectroscopic diagnostics designed for measurement of line integrated plasma radiation in two visible spectral ranges. This diagnostic system is aimed at measuring the bremsstrahlung absolute values and profile with high spatial resolution. The bremsstrahlung absolute values are used to determine the value and radial distribution of effective plasma ion charge Z eff( r) in T-10 discharges. The importance of Z eff measurement is due to its strong influence on plasma heating, confinement, and stability. The spatial distribution of emission for one of the chosen spectral lines is measured simultaneously with bremsstrahlung. The spatial resolution of measurements is 1 cm, and the temporal resolution is up to 10 ms. The spectral equipment and methods for its calibration are described. Examples of line integrated brightness distribution in a "continuum window" of 5236 ± 6 Å and brightness of the lines C5+ (5291 Å), He1+ (4686 Å), and Dβ (4861 Å) are given. Flattening of the bremsstrahlung brightness profile in the central region of the plasma column in some discharges with sawtooth oscillations in the T-10 is observed. The measured effective ion charge profiles in ohmic discharges with high plasma density and low discharge currents demonstrate accumulation of light impurities at the column axis; as a consequence, quenching of sawtooth oscillations in some discharges is observed. The developed diagnostics provides necessary data for investigation of heat, particle, and current transport in the plasma of the T-10. Successful application of the obtained data on Z eff( r) for investigation of geodesic acoustic modes of plasma oscillations in the T-10 should be specially noted.

  20. Non-Abelian bremsstrahlung and azimuthal asymmetries in high energy p+A reactions

    NASA Astrophysics Data System (ADS)

    Gyulassy, M.; Levai, P.; Vitev, I.; Biró, T. S.

    2014-09-01

    We apply the GLV reaction operator solution to the Vitev-Gunion-Bertsch (VGB) boundary conditions to compute to all orders in nuclear opacity the non-Abelian gluon bremsstrahlung of event-by-event fluctuating beam jets in nuclear collisions. We evaluate analytically azimuthal Fourier moments of single gluon, vnM{1}, and even numbered 2ℓ gluon distribution, vnM{2ℓ}, inclusive distributions in high-energy p +A reactions as a function of harmonic n, target recoil cluster number, M, and gluon number, 2ℓ, at the RHIC and LHC. Multiple resolved clusters of recoiling target beam jets together with the projectile beam jet form color scintillation antenna (CSA) arrays that lead to characteristic boost-noninvariant trapezoidal rapidity distributions in asymmetric B+A nuclear collisions. The scaling of the intrinsically azimuthally anisotropic and long range in η nature of the non-Abelian bremsstrahlung leads to vn moments that are similar to results from hydrodynamic models, but due entirely to non-Abelian wave interference phenomena sourced by the fluctuating CSA. Our analytic nonflow solutions are similar to recent numerical saturation model predictions but differ by predicting a simple power-law hierarchy of both even and odd vn without invoking kT factorization. A test of the CSA mechanism is the predicted nearly linear η rapidity dependence of the vn(kT,η). Non-Abelian beam jet bremsstrahlung may, thus, provide a simple analytic solution to the beam energy scan puzzle of the near √s independence of vn(pT) moments observed down to 10 AGeV, where large-x valence-quark beam jets dominate inelastic dynamics. Recoil bremsstrahlung from multiple independent CSA clusters could also provide a partial explanation for the unexpected similarity of vn in p(D)+A and noncentral A+A at the same dN/dη multiplicity as observed at the RHIC and LHC.

  1. Measurements of bremsstrahlung production and x-ray cryostat heating in VENUS

    SciTech Connect

    Lyneis, C.; Leitner, D.; Todd, D.; Virostek, S.; Loew, T.; Heinen, A.; Tarvainen, O.

    2006-03-15

    The VENUS superconducting electron cyclotron resonance (ECR) ion source is designed to operate at 28 GHz with up to 10 kW of rf power. Most of this power is absorbed by the plasma electrons and then dumped onto the plasma chamber wall. The distribution of heating and bremsstrahlung production is highly nonuniform and reflects the geometry of the magnetic confinement fields. The nonuniform distribution of electron losses to the wall results in localized heating on the aluminum chamber walls, which can lead to burnout. In addition, part of the bremsstrahlung produced by the collision of the hot-electrons with the walls is absorbed by the cold mass of the superconducting magnet leading to an additional heat load in the cryostat in the order of several watts. Therefore a new plasma chamber has been installed that incorporates a high-Z tantalum shield to reduce the cryostat heating and enhance water cooling to minimize the chance of burnout. In order to better understand the heat load, the spectrum of the bremsstrahlung has been carefully measured as a function of rf power, magnetic confinement, and rf frequency. In addition, the distribution of electron heating in VENUS magnetic field has been simulated with a three-dimensional computer code [H. Heinen and H. J. Andra, Proceedings of the 14th International Workshop on ECR Sources (CERN, Geneva, 1999), 224; H. J. Andra and A. Heinen, Proceedings of the 15th International Workshop on ECR lon Sources, ECRIS'02 (Jyvaeskylae, Finland 2002), 85.] to better understand the heat load distribution on the plasma chamber wall. The new plasma chamber design, results of the bremsstrahlung measurements, and the effectiveness of the high-Z shielding are described.

  2. Development of a 12 parabola observation system to detect Molecular Bremsstrahlung Radiation from air-showers

    NASA Astrophysics Data System (ADS)

    Yamamoto, T.; Ogio, S.; Akimune, H.; Fujii, T.; Sakurai, N.; Fukushima, M.; Sagawa, H.

    2013-05-01

    Two experiments for the detections of Molecular Bremsstrahlung Radiation (MBR) from air-shower are under development in West Japan. One of these systems consists of 12 parabola antennas. And the other one uses a 45 cm Broadcasting Satellite (BS) antenna in a scintillator array. Both experiments measure 12 GHz radio emission from air-showers. The setup and the status of these experiments will be reported.

  3. An instrument for the investigation of actinides with spin resolved photoelectron spectroscopy and bremsstrahlung isochromat spectroscopy

    SciTech Connect

    Yu, S.-W.; Tobin, J. G.; Chung, B. W.

    2011-01-01

    A new system for spin resolved photoelectron spectroscopy and bremsstrahlung isochromat spectroscopy has been built and commissioned at Lawrence Livermore National Laboratory for the investigation of the electronic structure of the actinides.Actinide materials are very toxic and radioactive and therefore cannot be brought to most general user facilities for spectroscopic studies. The technical details of the new system and preliminary data obtained therein will be presented and discussed.

  4. Optimal Design of Anger Camera for Bremsstrahlung Imaging: Monte Carlo Evaluation

    PubMed Central

    Walrand, Stephan; Hesse, Michel; Wojcik, Randy; Lhommel, Renaud; Jamar, François

    2014-01-01

    A conventional Anger camera is not adapted to bremsstrahlung imaging and, as a result, even using a reduced energy acquisition window, geometric x-rays represent <15% of the recorded events. This increases noise, limits the contrast, and reduces the quantification accuracy. Monte Carlo (MC) simulations of energy spectra showed that a camera based on a 30-mm-thick BGO crystal and equipped with a high energy pinhole collimator is well-adapted to bremsstrahlung imaging. The total scatter contamination is reduced by a factor 10 versus a conventional NaI camera equipped with a high energy parallel hole collimator enabling acquisition using an extended energy window ranging from 50 to 350 keV. By using the recorded event energy in the reconstruction method, shorter acquisition time and reduced orbit range will be usable allowing the design of a simplified mobile gantry. This is more convenient for use in a busy catheterization room. After injecting a safe activity, a fast single photon emission computed tomography could be performed without moving the catheter tip in order to assess the liver dosimetry and estimate the additional safe activity that could still be injected. Further long running time MC simulations of realistic acquisitions will allow assessing the quantification capability of such system. Simultaneously, a dedicated bremsstrahlung prototype camera reusing PMT–BGO blocks coming from a retired PET system is currently under design for further evaluation. PMID:24982849

  5. Bremsstrahlung enhancement in electron probe microanalysis for homogeneous samples using Monte Carlo simulation.

    PubMed

    Petaccia, M; Segui, S; Castellano, G

    2016-11-01

    Fluorescence enhancement in samples irradiated in a scanning electron microscope or an electron microprobe should be appropriately assessed in order not to distort quantitative analyses. Several models have been proposed to take into account this effect and current quantification routines are based on them, many of which have been developed under the assumption that bremsstrahlung fluorescence correction is negligible when compared to characteristic enhancement; however, no concluding arguments have been provided in order to support this assumption. As detectors are unable to discriminate primary from secondary characteristic X-rays, Monte Carlo simulation of radiation transport becomes a determinant tool in the study of this fluorescence enhancement. In this work, bremsstrahlung fluorescence enhancement in electron probe microanalysis has been studied by using the interaction forcing routine offered by penelope 2008 as a variance reduction alternative. The developed software allowed us to show that bremsstrahlung and characteristic fluorescence corrections are in fact comparable in the studied cases. As an extra result, the interaction forcing approach appears as a most efficient method, not only in the computation of the continuum enhancement but also for the assessment of the characteristic fluorescence correction.

  6. Dosimetric and bremsstrahlung performance of a single convergent beam for teletherapy device.

    PubMed

    Figueroa, R G; Santibáñez, M; Valente, M

    2016-12-01

    The present work investigates preliminary feasibility and characteristics of a new type of radiation therapy modality based on a single convergent beam of photons. The proposal consists of the design of a device capable of generating convergent X-ray beams useful for radiotherapy. The main goal is to achieve high concentrated dose delivery. The first step is an analytical approach in order to characterize the dosimetric performance of the hypothetical convergent photon beam. Then, the validated FLUKA Monte Carlo main code is used to perform complete radiation transport to account also for scattering effects. The proposed method for producing convergent X-rays is mainly based on the bremsstrahlung effect. Hence the operating principle of the proposed device is described in terms of bremsstrahlung production. The work is mainly devoted characterizing the effect on the bremsstrahlung yield due to accessories present in the device, like anode material and geometry, filtration and collimation systems among others. The results obtained for in-depth dose distributions, by means of analytical and stochastic approaches, confirm the presence of a high dose concentration around the irradiated target, as expected. Moreover, it is shown how this spot of high dose concentration depends upon the relevant physical properties of the produced convergent photon beam. In summary, the proposed design for producing single convergent X-rays attained satisfactory performance for achieving high dose concentration around small targets depending on beam spot size that may be used for some applications in radiotherapy, like radiosurgery.

  7. A model for low energy thick-target bremsstrahlung produced in an SEM

    NASA Astrophysics Data System (ADS)

    Quarles, C. A.; Semaan, Mars E.

    1999-10-01

    A model for thick-target bremsstrahlung has been developed based on the approach used by Storm ( E. Storm, Phys. Rev. A.5, 2328 (1972).)and Ambrose et al. ( R. Ambrose, D. L. Kahler, H. E. Lehtihet and C. A. Quarles, Nucl. Inst. Meth. Phys. Res. B 56/57, 327 (1991).). The model integrates the thin-target cross sections ( Kissel, C. A. Quarles and R. H. Pratt, Atom. Data Nucl. Data Tables 28, 381 (1983).) over the target taking into account electron energy loss, electron back scattering and photon attenuation. The model is compared with measurements in reflection mode for atomic numbers from 4 to 79 and for electron energies between 5 and 25 keV. A JEOL JSM 6100 Scanning Electron Microscope is used for the electron beam, and a Link Si(Li) detector for the bremsstrahlung spectrum. Very good agreement is found between the model and the experimental results. Sensitivity of the model to various assumptions about electron back scattering and photon attenuation will be discussed. The model is also found to do as well as a recent empirical model ( Trincavelli, G. Castellano and J. A. Riveros, X-Ray Spectr. 27, 81 (1998).) in describing the photon energy dependence of the bremsstrahlung spectrum.

  8. Equivalence of a tip bremsstrahlung quantum and an elastically scattered electron at ultrahigh energies

    NASA Astrophysics Data System (ADS)

    Jakubassa-Amundsen, D. H.

    2012-04-01

    In the scattering of relativistic spin-polarized electrons from point nuclei, two types of polarization correlations are compared: those of a left- or right-circular bremsstrahlung photon at the short-wavelength limit (when the outgoing electron is not observed) and those of an elastically scattered, left- or right-handed electron. Bremsstrahlung is calculated from the Dirac-Sommerfeld-Maue model, and elastic electron scattering is obtained from a partial-wave analysis. By considering a gold target and electron energies Ei up to 20 MeV, a striking similarity of the respective polarization correlations is found to develop when the collision energy is increased beyond 5 MeV. From analytical Born results for light targets it is shown that only for a longitudinally spin-polarized electron do the respective polarization correlations agree in the limit Ei→∞. In the general case, a very high nuclear charge is needed in addition, leading to a sum rule for bremsstrahlung well known from elastic electron scattering.

  9. High level tritiated water monitoring by Bremsstrahlung counting using a silicon drift detector

    SciTech Connect

    Niemes, S.; Sturm, M.; Michling, R.; Bornschein, B.

    2015-03-15

    The β-ray induced X-ray spectrometry (BIXS) is a promising technique to monitor the tritium concentration in a fuel cycle of a fusion reactor. For in-situ measurements of high level tritiated water by Bremsstrahlung counting, the characteristics of a low-noise silicon drift detector (SDD) have been examined at the Tritium Laboratory Karlsruhe (TLK). In static measurements with constant sample volume and tritium concentration, the Bremsstrahlung spectra of tritiated water samples in a concentration range of 0.02 to 15 MBq/ml have been obtained. The volume has been kept constant at 5 cm{sup 3}. The observed spectra are well above the noise threshold. In addition to X-rays induced by β-rays, the spectra feature X-ray fluorescence peaks of the surrounding materials. No indications of memory effects have been observed. A linear relation between the X-ray intensity and the tritium concentration was obtained and the lower detection limit of the setup has been determined to 1 MBq ml{sup -1}, assessed by the Curie criterion. In addition, the spectra obtained experimentally could be reproduced with high agreement by Monte-Carlo simulations using the GEANT4-tool-kit. It was found that the present detection system is applicable to non-invasive measurements of high-level tritiated water and the SDD is a convenient tool to detect the low energy Bremsstrahlung X-rays. (authors)

  10. Bremsstrahlung measurements for characterization of intense short-pulse, laser produced fast electrons with OMEGA EP

    NASA Astrophysics Data System (ADS)

    Daykin, Tyler; Sawada, Hiroshi; Sentoku, Yasuhiko; Pandit, Rishi; Chen, Cliff; Beg, Farhat; Chen, Hui; McLean, Harry; Patel, Pravesh; Tommasini, Riccardo

    2016-10-01

    Understanding relativistic fast electron generation and transport inside solids is important for applications such as generation of high energy x-ray sources and fast ignition. An experiment was carried out to study the scaling of the fast electron spectrum and bremsstrahlung generation in multi-pico second laser interactions using 1 ps and 10 ps OMEGA EP short-pulse beam to generate fast electrons at a similar peak intensity of 5x1018 W/cm2. The bremsstrahlung produced by collisions of the fast electrons with background ions was recorded using differential filter stacked spectrometers. A preliminary analysis with a Monte Carlo Code ITS shows that the electrons injection having an electron slope 1.8 MeV matched well with the high energy component of the 1 ps and 10 ps bremsstrahlung measurements. Details of the data analysis and modeling with Monte Carlo and a hybrid particle-in-cell codes will be presented at the conference. Work supported by the UNR Office of the Provost and by DOE/OFES under Contract No. DE-SC0008827. This collaborative work was partially supported under the auspices of the US DOE by LLNL under Contracts No. DE-AC52-07NA27344 and No. DE-FG-02-05ER54834.

  11. Bremsstrahlung Temperature Scaling in Ultra-Intense Laser-Plasma Interactions

    NASA Astrophysics Data System (ADS)

    Zulick, C.; Hou, B.; Nees, J.; Thomas, A. G. R.; Krushelnick, K.

    2011-10-01

    The absorption of laser energy during ultra-intense (I > 1018 W/cm2) laser-plasma interactions results in the production of a hot electron current, which can subsequently generate energetic protons, ions, and photons. The energetic photons are of particular interest in isomer excitation, positron production, and homeland security applications. Experiments were performed on the high repetition rate (500 Hz) Lambda Cubed laser (I ~ 5 .1018 , duration 30 fs) allowing high resolution (λ/ Δλ = 300) spectroscopy of X-ray and γ-ray bremsstrahlung photons in the 20 keV to 3 MeV energy range. The effective bremsstrahlung temperature was measured over a range of laser energies, target materials, and detection angles. Additionally, simulations (MCNPX and GEANT4) were used to correlate experimental bremsstrahlung temperatures with hot electron temperatures, which were compared to existing electron temperature scaling laws. This work was supported by the National Science Foundation (NSF) through the FOCUS Physics Frontier Center PHY-0114336, and by the Department of Homeland Security and NSF through grant EECS-0833499.

  12. Bremsstrahlung emission of high energy accompanying spontaneous fission of {sup 252}Cf

    SciTech Connect

    Maydanyuk, S. P.; Olkhovsky, V. S.; Mandaglio, G.; Manganaro, M.; Fazio, G.; Giardina, G.

    2010-07-15

    The study of the bremsstrahlung photon emission accompanying fragments produced in the spontaneous fission of heavy nuclei by a fully quantum approach is presented for the first time. This kind of problem requires the knowledge of wave functions of the fissioning system leading to a wide distribution of couples of fragments that are the products of fission. With the aim of obtaining these wave functions, the interaction potential between the emitted fragment and residual nucleus is calculated by a standard approach. A new procedure was performed that allows an increase in the accuracy of calculations of radial integrals in the far asymptotic region and the achievement of the convenient convergence in calculations of the spectra. The total probability of the emitted photons in the spontaneous fission of {sup 252}Cf was calculated in such a way. We obtained good agreement between theory and experimental data up to 38 MeV for the bremsstrahlung spectrum of photons while the calculation of the total probability of photon emission accompanying fragments was performed up to an energy of 60 MeV. The analysis of contributions in the bremsstrahlung spectrum accompanying the emission of light, medium, and heavy fragments in the fission of {sup 252}Cf is presented.

  13. On a discrete symmetry of the Bremsstrahlung function in {N} = 4 SYM

    NASA Astrophysics Data System (ADS)

    Beccaria, Matteo; Macorini, Guido

    2013-07-01

    We consider the quark anti-quark potential on the three sphere in planar {N} = 4 SYM and the associated vacuum potential in the near BPS limit with L units of R-charge. The associated Bremsstrahlung function B L has been recently computed analytically by means of the Thermodynamical Bethe Ansatz. We discuss it at strong coupling by computing it at large but finite L. We provide strong support to a special symmetry of the Bremsstrahlung function under the formal discrete {{{Z}}_2} symmetry L → -1 - L. In this context, it is the counterpart of the reciprocity invariance discovered in the past in the spectrum of various gauge invariant composite operators. The {{{Z}}_2} symmetry has remarkable consequences in the scaling limit where L is taken to be large with fixed ratio to the 't Hooft coupling. This limit organizes in inverse powers of the coupling and resembles the semiclassical expansion of the dual string theory which is indeed known to capture the leading classical term. We show that the various higher-order contributions to the Bremsstrahlung function obey several constraints and, in particular, the next-to-leading term, formally associated with the string one-loop correction, is completely determined by the classical contribution. The large L limit at strong coupling is also discussed.

  14. Ultra-Violet Light Emission from HPV-G Cells Irradiated with Low Let Radiation From (90)Y; Consequences for Radiation Induced Bystander Effects.

    PubMed

    Ahmad, Syed Bilal; McNeill, Fiona E; Byun, Soo Hyun; Prestwich, William V; Mothersill, Carmel; Seymour, Colin; Armstrong, Andrea; Fernandez, Cristian

    2013-01-01

    In this study, we aimed to establish the emission of UV photons when HPV-G cells and associated materials (such as the cell substrate and cell growth media) are exposed to low LET radiation. The potential role of UV photons in the secondary triggering of biological processes led us to hypothesize that the emission and absorption of photons at this wavelength explain some radiation induced "bystander effects" that have previously been thought to be chemically mediated. Cells were plated in Petri-dishes of two different sizes, having different thicknesses of polystyrene (PS) substrate, and were exposed to β-radiation from (90)Y produced by the McMaster Nuclear Reactor. UV measurements were performed using a single photon counting system employing an interference-type filter for selection of a narrow wavelength range, 340±5 nm, of photons. Exposure of the cell substrates (which were made of polystyrene) determined that UV photons were being emitted as a consequence of β particle irradiation of the Petri-dishes. For a tightly collimated β-particle beam exposure, we observed 167 photons in the detector per unit μCi in the shielded source for a 1.76 mm thick substrate and 158 photons/μCi for a 0.878 mm thick substrate. A unit μCi source activity was equivalent to an exposure to the substrate of 18 β-particles/cm(2) in this case. The presence of cells and medium in a Petri-dish was found to significantly increase (up to a maximum of 250%) the measured number of photons in a narrow band of wavelengths of 340±5 nm (i.e. UVA) as compared to the signal from an empty control Petri-dish. When coloured growth medium was added to the cells, it reduced the measured count rate, while the addition of transparent medium in equal volume increased the count rate, compared to cells alone. We attribute this to the fact that emission, scattering and absorption of light by cells and media are all variables in the experiment. Under collimated irradiation conditions, it was observed

  15. Ultra-Violet Light Emission from HPV-G Cells Irradiated with Low Let Radiation From 90Y; Consequences for Radiation Induced Bystander Effects

    PubMed Central

    Ahmad, Syed Bilal; McNeill, Fiona E.; Byun, Soo Hyun; Prestwich, William V.; Mothersill, Carmel; Seymour, Colin; Armstrong, Andrea; Fernandez, Cristian

    2013-01-01

    In this study, we aimed to establish the emission of UV photons when HPV-G cells and associated materials (such as the cell substrate and cell growth media) are exposed to low LET radiation. The potential role of UV photons in the secondary triggering of biological processes led us to hypothesize that the emission and absorption of photons at this wavelength explain some radiation induced “bystander effects” that have previously been thought to be chemically mediated. Cells were plated in Petri-dishes of two different sizes, having different thicknesses of polystyrene (PS) substrate, and were exposed to β-radiation from 90Y produced by the McMaster Nuclear Reactor. UV measurements were performed using a single photon counting system employing an interference-type filter for selection of a narrow wavelength range, 340±5 nm, of photons. Exposure of the cell substrates (which were made of polystyrene) determined that UV photons were being emitted as a consequence of β particle irradiation of the Petri-dishes. For a tightly collimated β-particle beam exposure, we observed 167 photons in the detector per unit μCi in the shielded source for a 1.76 mm thick substrate and 158 photons/μCi for a 0.878 mm thick substrate. A unit μCi source activity was equivalent to an exposure to the substrate of 18 β-particles/cm2 in this case. The presence of cells and medium in a Petri-dish was found to significantly increase (up to a maximum of 250%) the measured number of photons in a narrow band of wavelengths of 340±5 nm (i.e. UVA) as compared to the signal from an empty control Petri-dish. When coloured growth medium was added to the cells, it reduced the measured count rate, while the addition of transparent medium in equal volume increased the count rate, compared to cells alone. We attribute this to the fact that emission, scattering and absorption of light by cells and media are all variables in the experiment. Under collimated irradiation conditions, it was observed

  16. PET/CT-Based Dosimetry in 90Y-Microsphere Selective Internal Radiation Therapy: Single Cohort Comparison With Pretreatment Planning on (99m)Tc-MAA Imaging and Correlation With Treatment Efficacy.

    PubMed

    Song, Yoo Sung; Paeng, Jin Chul; Kim, Hyo-Cheol; Chung, Jin Wook; Cheon, Gi Jeong; Chung, June-Key; Lee, Dong Soo; Kang, Keon Wook

    2015-06-01

    ⁹⁰Y PET/CT can be acquired after ⁹⁰Y-microsphere selective radiation internal therapy (SIRT) to describe radioactivity distribution. We performed dosimetry using ⁹⁰Y-microsphere PET/CT data to evaluate treatment efficacy and appropriateness of activity planning from (99m)Tc-MAA scan and SPECT/CT. Twenty-three patients with liver malignancy were included in the study. (99m)Tc-MAA was injected during planning angiography and whole body (99m)Tc-MAA scan and liver SPECT/CT were acquired. After SIRT using ⁹⁰Y-resin microsphere, ⁹⁰Y-microsphere PET/CT was acquired. A partition model (PM) using 4 compartments (tumor, intarget normal liver, out-target normal liver, and lung) was adopted, and absorbed dose to each compartment was calculated based on measurements from (99m)Tc-MAA SPECT/CT and ⁹⁰Y-microsphere PET/CT, respectively, to be compared with each other. Progression-free survival (PFS) was evaluated in terms of tumor absorbed doses calculated by (99m)Tc-MAA SPECT/CT and ⁹⁰Y-microsphere PET/CT results. Lung shunt fraction was overestimated on (99m)Tc-MAA scan compared with ⁹⁰Y-microsphere PET/CT (0.060 ± 0.037 vs. 0.018 ± 0.026, P < 0.01). Tumor absorbed dose exhibited a close correlation between the results from (99m)Tc-MAA SPECT/CT and ⁹⁰Y-microsphere PET/CT (r = 0.64, P < 0.01), although the result from (99m)Tc-MAA SPECT/CT was significantly lower than that from ⁹⁰Y-microsphere PET/CT (135.4 ± 64.2 Gy vs. 185.0 ± 87.8 Gy, P < 0.01). Absorbed dose to in-target normal liver was overestimated on (99m)Tc-MAA SPECT/CT compared with PET/CT (62.6 ± 38.2 Gy vs. 45.2 ± 32.0 Gy, P = 0.02). Absorbed dose to out-target normal liver did not differ between (99m)Tc-MAA SPECT/CT and ⁹⁰Y-microsphere PET/CT (P = 0.49). Patients with tumor absorbed dose >200 Gy on ⁹⁰Y-microsphere PET/CT had longer PFS than those with tumor absorbed dose ≤200 Gy (286 ± 56 days vs. 92 ± 20

  17. Multimodality tomographic scintimammography with PET, PECI, and SPECT: initial evaluation

    NASA Astrophysics Data System (ADS)

    Krol, Andrzej; Feiglin, David H.; Thomas, Frank D.; Hellwig, Bradford J.; Gagne, George M.

    2002-04-01

    We compared tomographic scintimammography performed using single photon emission computed tomography (SPECT), positron emission coincidence imaging (PECI) and positron emission tomography (PET). A female thorax phantom was used. Activities of the myocardium, thorax and breasts were adjusted to emulate the count rate observed with patients. Hollow plastic spheres, imitating hot lesions (1.5-20ml), filled with radioactive saline were inserted in the center of each breast. Specific activities of internal organs were adjusted to emulate the count rate observed with patients. SPECT data were acquired with Tc-99m using gamma cameras with NaI(Tl) detectors. A modified FBP (CODE) reconstruction algorithm was used to render SPECT tomographic images. PECI (Siemens E.CAM with NaI(Tl)) and PET (GE Advance with BGO) data were acquired using F-18 FDG. Vendor supplied reconstruction algorithms were used. The reconstructed hot lesions contrast and resolution were investigated. Image quality obtained can be ranked as follows: (1) PET(BGO), (2) PECI(NaI), (3) SPECT(NaI) In conclusion, assuming comparable uptake values of Tc-99m-sestamibi and F-18 FDG, PET seems to be a superior methodology in visualization of breast lesion as compared to SPECT and PECI. All these tomographic methods appear to be promising adjunct to x-ray mammography in difficult to interpret cases.

  18. Recent developments and future prospects of SPECT myocardial perfusion imaging.

    PubMed

    Zaman, Maseeh Uz; Hashmi, Ibrahim; Fatima, Nosheen

    2010-10-01

    Myocardial perfusion SPECT imaging is the most commonly performed functional imaging for assessment of coronary artery disease. High diagnostic accuracy and incremental prognostic value are the major benefits while suboptimal spatial resolution and significant radiation exposure are the main limitations. Its ability to detect hemodynamic significance of lesions seen on multidetector CT angiogram (MDCTA) has paved the path for a successful marriage between anatomical and functional imaging modalities in the form of hybrid SPECT/MDCTA system. In recent years, there have been enormous efforts by industry and academia to develop new SPECT imaging systems with better sensitivity, resolution, compact design and new reconstruction algorithms with ability to improve image quality and resolution. Furthermore, expected arrival of Tc-99m-labeled deoxyglucose in next few years would further strengthen the role of SPECT in imaging hibernating myocardium. In view of these developments, it seems that SPECT would enjoy its pivotal role in spite of major threat to be replaced by fluorine-18-labeled positron emission tomography perfusion and glucose metabolism imaging agents.

  19. Enhancing the utility of prostascint SPECT scans for patient management.

    PubMed

    Noz, Marilyn E; Chung, Grace; Lee, Benjamin Y; Maguire, Gerald Q; DeWyngaert, J Keith; Doshi, Jay V; Kramer, Elissa L; Murphy-Walcott, Antoinette D; Zeleznik, Michael P; Kwak, Noeun G

    2006-04-01

    This project investigated reducing the artifact content of In-ill ProstaScint SPECT scans for use in treatment planning and management. Forty-one patients who had undergone CT or MRI scans and simultaneous Tc-99m RBC/In-111 ProstaScint SPECT scans were included. SPECT volume sets, reconstructed using Ordered Set-Expectation Maximum (OS-EM) were compared against those reconstructed with standard Filtered Back projection (FBP). Bladder activity in Tc-99m scans was suppressed within an ellipsoidal volume. Tc-99m voxel values were subtracted from the corresponding In-111 after scaling based on peak activity within the descending aorta. The SPECT volume data sets were merged with the CT or MRI scans before and after processing. Volume merging, based both on visual assessment and statistical evaluation, was not affected. Thus iterative reconstruction together with bladder suppression and blood pool subtraction may improve the interpretation and utility of ProstaScint SPECT scans for patient management.

  20. A SPECT imager with synthetic collimation

    NASA Astrophysics Data System (ADS)

    Havelin, Ronan J.; Miller, Brian W.; Barrett, Harrison H.; Furenlid, Lars R.; Murphy, J. M.; Foley, Mark J.

    2013-09-01

    This work outlines the development of a multi-pinhole SPECT system designed to produce a synthetic-collimator image of a small field of view. The focused multi-pinhole collimator was constructed using rapid-prototyping and casting techniques. The collimator projects the field of view through forty-six pinholes when the detector is adjacent to the collimator. The detector is then moved further from the collimator to increase the magnification of the system. The amount of pinhole-projection overlap increases with the system magnification. There is no rotation in the system; a single tomographic angle is used in each system configuration. The maximum-likelihood expectation-maximization (MLEM) algorithm is implemented on graphics processing units to reconstruct the object in the field of view. Iterative reconstruction algorithms, such as MLEM, require an accurate model of the system response. For each system magnification, a sparsely-sampled system response is measured by translating a point source through a grid encompassing the field of view. The pinhole projections are individually identified and associated with their respective apertures. A 2D elliptical Gaussian model is applied to the pinhole projections on the detector. These coefficients are associated with the object-space location of the point source, and a finely-sampled system matrix is interpolated. Simulations with a hot-rod phantom demonstrate the efficacy of combining low-resolution non-multiplexed data with high-resolution multiplexed data to produce high-resolution reconstructions.

  1. Dose assessment of bremsstrahlung induced by beta-emitting radioisotopes of uranium-238 series and lead in human tissues.

    PubMed

    Manjunatha, H C

    2014-01-01

    In the natural uranium-238 decay series, pure beta isotopes such as (234)Th, (234)Pa, (214)Pb, (214)Bi, (210)Pb and (210)Bi are released. The few lead isotopes such as (211)Pb, (212)Pb, (213)Pb and (215)Pb are good beta emitters. In certain nuclear reactions of reactor these isotopes are released. These beta isotopes have maximum beta energies, which induce the bremsstrahlung radiation. The bremsstrahlung component of these beta isotopes has been traditionally ignored in dosimetry calculations. The shapes of bremsstrahlung spectra are a basic ingredient in the understanding and quantification of beta-ray dosimetry. The bremsstrahlung spectra produced by these high-energy isotopes such as (234)Th, (234)Pa, (214)Pb, (214)Bi, (210)Pb, (210)Bi, (211)Pb, (212)Pb, (213)Pb and (215)Pb in bone, muscle and teeth are studied, and the computed spectral distributions are presented. The spectral shapes are primarily responsible for variations in the shapes of depth-dose distributions. They are intended to provide a quick and convenient reference for spectral shapes and to give an indication of the wide variation in these shapes. The evaluated beta bremsstrahlung dose as a function distance for the studied nuclides is also presented. The efficiency, intensity and dose rate of bremsstrahlung induced by beta isotopes of natural uranium-238 decay series and beta-emitting lead isotopes in human tissues such as brain, breast, heart, kidney, liver, muscle, pancreas and bone have also been studied in the present investigation. The values of bremsstrahlung dosimetric parameters are low for pancreas, but they are high for bone. For all studied tissues these parameters are high for (234)Pa, but low for (210)Pb.

  2. MULTIMODALITY IMAGING: BEYOND PET/CT AND SPECT/CT

    PubMed Central

    Cherry, Simon R.

    2009-01-01

    Multimodality imaging with PET/CT and SPECT/CT has become commonplace in clinical practice and in preclinical and basic medical research. Do other combinations of imaging modalities have a similar potential to impact medical science and clinical medicine? The combination of PET or SPECT with MRI is an area of active research at the present time, while other, perhaps less obvious combinations, including CT/MR and PET/optical also are being studied. In addition to the integration of the instrumentation, there are parallel developments in synthesizing imaging agents that can be viewed by multiple imaging modalities. Is the fusion of PET and SPECT with CT the ultimate answer in multimodality imaging, or is it just the first example of a more general trend towards harnessing the complementary nature of the different modalities on integrated imaging platforms? PMID:19646559

  3. 3D quantitative analysis of brain SPECT images

    NASA Astrophysics Data System (ADS)

    Loncaric, Sven; Ceskovic, Ivan; Petrovic, Ratimir; Loncaric, Srecko

    2001-07-01

    The main purpose of this work is to develop a computer-based technique for quantitative analysis of 3-D brain images obtained by single photon emission computed tomography (SPECT). In particular, the volume and location of ischemic lesion and penumbra is important for early diagnosis and treatment of infracted regions of the brain. SPECT imaging is typically used as diagnostic tool to assess the size and location of the ischemic lesion. The segmentation method presented in this paper utilizes a 3-D deformable model in order to determine size and location of the regions of interest. The evolution of the model is computed using a level-set implementation of the algorithm. In addition to 3-D deformable model the method utilizes edge detection and region growing for realization of a pre-processing. Initial experimental results have shown that the method is useful for SPECT image analysis.

  4. Determination of left ventricular mass through SPECT imaging

    NASA Astrophysics Data System (ADS)

    Zárate-Morales, A.; Rodríguez-Villafuerte, M.; Martínez-Rodríguez, F.; Arévila-Ceballos, N.

    1998-08-01

    An edge detection algorithm has been applied to estimate left ventricular (LV) mass from single photon emission computed tomography (SPECT) thallium-201 images. The algorithm was validated using SPECT images of a phantom. The algorithm was applied to 20 patient studies from the Hospital de Cardiologia, Centro Médico Nacional Siglo XXI. Left ventricular masses derived from the stress and redistribution studies were highly correlated (r=0.96). The average LV masses obtained were 162±37 g and 169±34 g in the redistribution and stress studies, respectively.

  5. Determination of left ventricular mass through SPECT imaging

    SciTech Connect

    Zarate-Morales, A.; Rodriguez-Villafuerte, M.; Martinez-Rodriguez, F.; Arevila-Ceballos, N.

    1998-08-28

    An edge detection algorithm has been applied to estimate left ventricular (LV) mass from single photon emission computed tomography (SPECT) thallium-201 images. The algorithm was validated using SPECT images of a phantom. The algorithm was applied to 20 patient studies from the Hospital de Cardiologia, Centro Medico Nacional Siglo XXI. Left ventricular masses derived from the stress and redistribution studies were highly correlated (r=0.96). The average LV masses obtained were 162{+-}37 g and 169{+-}34 g in the redistribution and stress studies, respectively.

  6. Time evolution of endpoint energy of Bremsstrahlung spectra and ion production from an electron cyclotron resonance ion source

    SciTech Connect

    Tarvainen, Ollie; Ropponen, Tommi; Jones, Peter; Kalvas, Taneli

    2008-01-01

    Electron cyclotron resonance ion sources (ECRIS) are used to produce high charge state heavy ion beams for the use of nuclear and materials science, for instance. The most powerful ECR ion sources today are superconducting. One of the problems with superconducting ECR ion sources is the use of high radio frequency (RF) power which results in bremsstrahlung radiation adding an extra heat load to the cryostat. In order to understand the electron heating process and timescales in the ECR plasma, time evolution measurement of ECR bremsstrahlung was carried out. In the measurements JYFL 14 GHz ECRIS was operated in a pulsed mode and bremsstrahlung data from several hundred RF pulses was recorded. Time evolution of ion production was also studied and compared to one of the electron heating theories. To analyze the measurement data at C++ program was developed. Endpoint energies of the bremsstrahlung spectra as a function of axial magnetic field strength, pressure and RF power are presented and ion production timescales obtained from the measurements are compared to bremsstrahlung emission timescales and one of the stochastic heating theories.

  7. The stonehenge technique: a new method of crystal alignment for coherent bremsstrahlung experiments

    NASA Astrophysics Data System (ADS)

    Livingston, Kenneth

    2005-08-01

    In the coherent bremsstrahlung technique a thin diamond crystal oriented correctly in an electron beam can produce photons with a high degree of linear polarization.1 The crystal is mounted on a goniometer to control its orientation and it is necessary to measure the angular offsets a) between the crystal axes and the goniometer axes and b) between the goniometer and the electron beam axis. A method for measuring these offsets and aligning the crystal was developed by Lohman et al, and has been used successfully in Mainz.2 However, recent attempts to investigate new crystals have shown that this approach has limitations which become more serious at higher beam energies where more accurate setting of the crystal angles, which scale with l/Ebeam, is required. (Eg. the recent installation of coherent bremsstrahlung facility at Jlab, with Ebeam = 6 GeV ) This paper describes a new, more general alignment technique, which overcomes these limitations. The technique is based on scans where the horizontal and vertical rotation axes of the goniometer are adjusted in a series of steps to make the normal to the crystal describe a cone of a given angle. For each step in the scan, the photon energy spectrum is measured using a tagging spectrometer, and the offsets between the electron beam and the crystal lattice are inferred from the resulting 2D plot. Using this method, it is possible to align the crystal with the beam quickly, and hence to set any desired orientation of the crystal relative to the beam. This is essential for any experiment requiring linearly polarized photons produced via coherent bremsstrahlung, and is also required for a systematic study of the channeling radiation produced by the electron beam incident on the crystal.

  8. Secondary bremsstrahlung and the energy-conservation aspects of kerma in photon-irradiated media.

    PubMed

    Kumar, Sudhir; Nahum, Alan E

    2016-02-07

    Kerma, collision kerma and absorbed dose in media irradiated by megavoltage photons are analysed with respect to energy conservation. The user-code DOSRZnrc was employed to compute absorbed dose D, kerma K and a special form of kerma, K ncpt, obtained by setting the charged-particle transport energy cut-off very high, thereby preventing the generation of 'secondary bremsstrahlung' along the charged-particle paths. The user-code FLURZnrc was employed to compute photon fluence, differential in energy, from which collision kerma, K col and K were derived. The ratios K/D, K ncpt/D and K col/D have thereby been determined over a very large volumes of water, aluminium and copper irradiated by broad, parallel beams of 0.1 to 25 MeV monoenergetic photons, and 6, 10 and 15 MV 'clinical' radiotherapy qualities. Concerning depth-dependence, the 'area under the kerma, K, curve' exceeded that under the dose curve, demonstrating that kerma does not conserve energy when computed over a large volume. This is due to the 'double counting' of the energy of the secondary bremsstrahlung photons, this energy being (implicitly) included in the kerma 'liberated' in the irradiated medium, at the same time as this secondary bremsstrahlung is included in the photon fluence which gives rise to kerma elsewhere in the medium. For 25 MeV photons this 'violation' amounts to 8.6%, 14.2% and 25.5% in large volumes of water, aluminium and copper respectively but only 0.6% for a 'clinical' 6 MV beam in water. By contrast, K col/D and K ncpt/D, also computed over very large phantoms of the same three media, for the same beam qualities, are equal to unity within (very low) statistical uncertainties, demonstrating that collision kerma and the special type of kerma, K ncpt, do conserve energy over a large volume. A comparison of photon fluence spectra for the 25 MeV beam at a depth of  ≈51 g cm−2 for both very high and very low charged-particle transport cut-offs reveals the considerable

  9. Non-Abelian Bremsstrahlung and Azimuthal Asymmetries in High Energy p+A Reactions

    DOE PAGES

    Gyulassy, Miklos; Vitev, Ivan Mateev; Levai, Peter; ...

    2014-09-25

    Here we apply the GLV reaction operator solution to the Vitev-Gunion-Bertsch (VGB) boundary conditions to compute the all-order in nuclear opacity non-abelian gluon bremsstrahlung of event- by-event uctuating beam jets in nuclear collisions. We evaluate analytically azimuthal Fourier moments of single gluon, vmore » $$M\\atop{n}$$ {1}, and even number 2ℓ gluon, v$$M\\atop{n}$$ {2ℓ} inclusive distributions in high energy p+A reactions as a function of harmonic $n$, target recoil cluster number, $M$, and gluon number, 2ℓ, at RHIC and LHC. Multiple resolved clusters of recoiling target beam jets together with the projectile beam jet form Color Scintillation Antenna (CSA) arrays that lead to character- istic boost non-invariant trapezoidal rapidity distributions in asymmetric B+A nuclear collisions. The scaling of intrinsically azimuthally anisotropic and long range in η nature of the non-Abelian bremsstrahlung leads to vn moments that are similar to results from hydrodynamic models, but due entirely to non-Abelian wave interference phenomena sourced by the fluctuating CSA. Our analytic non-flow solutions are similar to recent numerical saturation model predictions but differ by predicting a simple power-law hierarchy of both even and odd vn without invoking kT factorization. A test of CSA mechanism is the predicted nearly linear η rapidity dependence of the vn(kTη). Non- Abelian beam jet bremsstrahlung may thus provide a simple analytic solution to Beam Energy Scan (BES) puzzle of the near $$\\sqrt{s}$$ independence of vn(pT) moments observed down to 10 AGeV where large-x valence quark beam jets dominate inelastic dynamics. Recoil bremsstrahlung from multiple independent CSA clusters could also provide a partial explanation for the unexpected similarity of vn in p(D) + A and non-central A + A at same dN=dη multiplicity as observed at RHIC and LHC.« less

  10. A technique for interpretation of auroral bremsstrahlung X-ray spectra

    NASA Technical Reports Server (NTRS)

    Robinson, Robert M.; Davidson, Gerald T.; Vondrak, Richard R.; Francis, William E.; Walt, Martin

    1989-01-01

    A procedure is described for determining the average energy and the energy flux of precipitating electrons from the resulting bremsstrahlung X-rays based on the assumption that the precipitating electrons have an exponential electron distribution. It is shown that, for nonexponential electron distributions, this method yields an exponential electron distribution that produces an altitude profile of ionization very similar to that expected from the actual spectrum. The Hall and Pedersen electrical conductances calculated from the inferred ionization profile were also found to be close to the true values.

  11. Effect of electron collisions on transport coefficients induced by the inverse bremsstrahlung absorption in plasmas

    SciTech Connect

    Bendib, A.; Tahraoui, A.; Bendib, K.; Mohammed El Hadj, K.; Hueller, S.

    2005-03-01

    The transport coefficients of fully ionized plasmas under the influence of a high-frequency electric field are derived solving numerically the electron Fokker-Planck equation using a perturbation method, parametrized as a function of the electron mean-free-path {lambda}{sub ei} compared to the spatial scales L. The isotropic and anisotropic contributions of the inverse bremsstrahlung heating are considered. Electron-electron collision terms are kept in the analysis, which allows us to consider with sufficient accuracy to describe plasmas with arbitrary atomic number Z. Practical numerical fits of the transport coefficients are proposed as functions of Z and the collisionality parameter {lambda}{sub ei}/L.

  12. Emerging Hawking-Like Radiation from Gravitational Bremsstrahlung Beyond the Planck Scale.

    PubMed

    Ciafaloni, Marcello; Colferai, Dimitri; Veneziano, Gabriele

    2015-10-23

    We argue that, as a consequence of the graviton's spin-2, its bremsstrahlung in trans-Planckian-energy (E≫M(P)) gravitational scattering at small deflection angle can be nicely expressed in terms of helicity-transformation phases and their transfer within the scattering process. The resulting spectrum exhibits deeply sub-Planckian characteristic energies of order M(P)(2)/E≪M(P) (reminiscent of Hawking radiation), a suppressed fragmentation region, and a reduced rapidity plateau, in broad agreement with recent classical estimates.

  13. Monte Carlo analysis of energy dependent anisotropy of bremsstrahlung x-ray spectra

    SciTech Connect

    Kakonyi, Robert; Erdelyi, Miklos; Szabo, Gabor

    2009-09-15

    The energy resolved emission angle dependence of x-ray spectra was analyzed by MCNPX (Monte Carlo N particle Monte Carlo) simulator. It was shown that the spectral photon flux had a maximum at a well-defined emission angle due to the anisotropy of the bremsstrahlung process. The higher the relative photon energy, the smaller the emission angle belonging to the maximum was. The trends predicted by the Monte Carlo simulations were experimentally verified. The Monte Carlo results were compared to both the Institute of Physics and Engineering in Medicine spectra table and the SPEKCALCV1.0 code.

  14. Non-Abelian Bremsstrahlung and Azimuthal Asymmetries in High Energy p+A Reactions

    SciTech Connect

    Gyulassy, Miklos; Vitev, Ivan Mateev; Levai, Peter; Biro, Tamas S.

    2014-09-25

    Here we apply the GLV reaction operator solution to the Vitev-Gunion-Bertsch (VGB) boundary conditions to compute the all-order in nuclear opacity non-abelian gluon bremsstrahlung of event- by-event uctuating beam jets in nuclear collisions. We evaluate analytically azimuthal Fourier moments of single gluon, v$M\\atop{n}$ {1}, and even number 2ℓ gluon, v$M\\atop{n}$ {2ℓ} inclusive distributions in high energy p+A reactions as a function of harmonic $n$, target recoil cluster number, $M$, and gluon number, 2ℓ, at RHIC and LHC. Multiple resolved clusters of recoiling target beam jets together with the projectile beam jet form Color Scintillation Antenna (CSA) arrays that lead to character- istic boost non-invariant trapezoidal rapidity distributions in asymmetric B+A nuclear collisions. The scaling of intrinsically azimuthally anisotropic and long range in η nature of the non-Abelian bremsstrahlung leads to vn moments that are similar to results from hydrodynamic models, but due entirely to non-Abelian wave interference phenomena sourced by the fluctuating CSA. Our analytic non-flow solutions are similar to recent numerical saturation model predictions but differ by predicting a simple power-law hierarchy of both even and odd vn without invoking kT factorization. A test of CSA mechanism is the predicted nearly linear η rapidity dependence of the vn(kTη). Non- Abelian beam jet bremsstrahlung may thus provide a simple analytic solution to Beam Energy Scan (BES) puzzle of the near $\\sqrt{s}$ independence of vn(pT) moments observed down to 10 AGeV where large-x valence quark beam jets dominate inelastic dynamics. Recoil bremsstrahlung from multiple independent CSA clusters could also provide a partial explanation for the unexpected similarity of vn in p(D) + A and non-central A + A at same dN=dη multiplicity as observed at RHIC and LHC.

  15. Coincidence measurement of the fully differential cross section for atomic-field bremsstrahlung

    NASA Technical Reports Server (NTRS)

    Faulk, J. D.; Quarles, C. A.

    1974-01-01

    A coincidence measurement was made of the absolute cross section for electron-atomic-field bremsstrahlung, differential in photon energy, photon-emission angle, and electron scattering angle. The incident electron energy was 140 keV and the scattering materials were thin films of aluminum and gold. The data are compared to the theoretical calculations of Elwert and Haug and of Bethe and Heitler. Both theories give generally satisfactory agreement for aluminum. The Elwert-Haug theory is somewhat more accurate for gold.

  16. Role of SPECT and SPECT/CT in the Surgical Treatment of Primary Hyperparathyroidism

    PubMed Central

    Taubman, Michele L.; Goldfarb, Melanie; Lew, John I.

    2011-01-01

    Primary hyperparathyroidism is the most common cause of hypercalcemia in the outpatient population. This condition is usually the result of a single hyperfunctioning parathyroid gland. Targeted parathyroidectomy guided by intraoperative parathyroid hormone monitoring (IPM) through a small cervical incision has replaced traditional bilateral neck exploration (BNE) as the initial approach in the surgical treatment of primary hyperparathyroidism at many medical centers worldwide. Preoperative sestamibi-technetium 99m scintigraphy serves as an important prerequisite for successful targeted parathyroidectomy. Single-photon emission computed tomography (SPECT) and CT fusion, however, is a recent imaging technique that provides a three-dimensional functional image with advanced contrast resolution to greatly improve preoperative localization of parathyroid tumors. PMID:21776381

  17. Molecular Imaging of Conscious, Unrestrained Mice with AwakeSPECT

    SciTech Connect

    Baba, Justin S; Endres, Christopher; Foss, Catherine; Nimmagadda, Sridhar; Jung, Hyeyun; Goddard Jr, James Samuel; Lee, Seung Joon; McKisson, John; Smith, Mark F.; Stolin, Alexander; Weisenberger, Andrew G.; Pomper, Martin

    2013-01-01

    We have developed a SPECT imaging system, AwakeSPECT, to enable molecular brain imaging of untrained mice that are conscious, unanesthetized, and unrestrained. We accomplished this with head tracking and motion correction techniques. Methods: The capability of the system for motion-corrected imaging was demonstrated with a 99mTc-pertechnetate phantom, 99mTcmethylene diphosphonate bone imaging, and measurement of the binding potential of the dopamine transporter radioligand 123I-ioflupane in mouse brain in the awake and anesthetized (isoflurane) states. Stress induced by imaging in the awake state was assessed through measurement of plasma corticosterone levels. Results: AwakeSPECT provided high-resolution bone images reminiscent of those obtained from CT. The binding potential of 123I-ioflupane in the awake state was on the order of 50% of that obtained with the animal under anesthesia, consistent with previous studies in nonhuman primates. Levels of stress induced were on the order of those seen in other behavioral tasks and imaging studies of awake animals. Conclusion: These results demonstrate the feasibility of SPECT molecular brain imaging of mice in the conscious, unrestrained state and demonstrate the effects of isoflurane anesthesia on radiotracer uptake.

  18. Molecular Imaging of Conscious, Unrestrained Mice with AwakeSPECT

    SciTech Connect

    Baba, Justin S.; Endres, Christopher J.; Foss, Catherine A.; Nimmagadda, Sridhar; Jung, Hyeyun; Goddard, James S.; Lee, Seung Joon; McKisson, John; Smith, Mark F.; Stolin, Alexander V.; Weisenberger, Andrew G.; Pomper, Martin G.

    2013-06-01

    We have developed a SPECT imaging system, AwakeSPECT, to enable molecular brain imaging of untrained mice that are conscious, unanesthetized, and unrestrained. We accomplished this with head tracking and motion correction techniques. Methods: The capability of the system for motion-corrected imaging was demonstrated with a ^99mTc-pertechnetate phantom, ^99mTc-methylene diphosphonate bone imaging, and measurement of the binding potential of the dopamine transporter radioligand ^123I-ioflupane in mouse brain in the awake and anesthetized (isoflurane) states. Stress induced by imaging in the awake state was assessed through measurement of plasma corticosterone levels. Results: AwakeSPECT provided high-resolution bone images reminiscent of those obtained from CT. The binding potential of ^123I-ioflupane in the awake state was on the order of 50% of that obtained with the animal under anesthesia, consistent with previous studies in nonhuman primates. Levels of stress induced were on the order of those seen in other behavioral tasks and imaging studies of awake animals. Conclusion: These results demonstrate the feasibility of SPECT molecular brain imaging of mice in the conscious, unrestrained state and demonstrate the effects of isoflurane anesthesia on radiotracer uptake.

  19. Small hepatocellular carcinomas in chronic liver disease: Detection with SPECT

    SciTech Connect

    Kudo, M.; Hirasa, M.; Takakuwa, H.; Ibuki, Y.; Fujimi, K.; Miyamura, M.; Tomita, S.; Komori, H.; Todo, A.; Kitaura, Y.

    1986-06-01

    Single-photon emission computed tomography (SPECT) performed using a rotating gamma camera was compared with ..cap alpha../sub 1/-fetoprotein (AFP) assay, conventional liver scintigraphy, ultrasound (US) imaging, computed tomography (CT), and selective celiac angiography in 40 patients with a total of 50 small hepatocellular carcinomas (HCCs;<5 cm). The detection rates of US and CT were determined on an initial screening study and on a second, more precisely focused study. The detection rate of small HCCs by the various modalities was as follows: AFP, 13%; liver scintigraphy, 36%; SPECT, 72%; initial screening US, 80%; second, more precise US studies, 94%; initial screening CT, 64%; second, more precise CT study, 82%; angiography, 88%. Although SPECT was inferior to the initial screening US examination in detecting HCCs less than 2 cm in size, its sensitivity was identical to that of the initial screening US study for detecting HCCs of 2-5 cm. The combination of SPECT and US was an excellent method for the early detection of HCCs, yielding a detection rate of 94%.

  20. A COMPUTER MODEL OF LUNG MORPHOLOGY TO ANALYZE SPECT IMAGES

    EPA Science Inventory

    Measurement of the three-dimensional (3-D) spatial distribution of aerosol deposition can be performed using Single Photon Emission Computed Tomography (SPECT). The advantage of using 3-D techniques over planar gamma imaging is that deposition patterns can be related to real lun...

  1. Nonlinear Dual Reconstruction of SPECT Activity and Attenuation Images

    PubMed Central

    Liu, Huafeng; Guo, Min; Hu, Zhenghui; Shi, Pengcheng; Hu, Hongjie

    2014-01-01

    In single photon emission computed tomography (SPECT), accurate attenuation maps are needed to perform essential attenuation compensation for high quality radioactivity estimation. Formulating the SPECT activity and attenuation reconstruction tasks as coupled signal estimation and system parameter identification problems, where the activity distribution and the attenuation parameter are treated as random variables with known prior statistics, we present a nonlinear dual reconstruction scheme based on the unscented Kalman filtering (UKF) principles. In this effort, the dynamic changes of the organ radioactivity distribution are described through state space evolution equations, while the photon-counting SPECT projection data are measured through the observation equations. Activity distribution is then estimated with sub-optimal fixed attenuation parameters, followed by attenuation map reconstruction given these activity estimates. Such coupled estimation processes are iteratively repeated as necessary until convergence. The results obtained from Monte Carlo simulated data, physical phantom, and real SPECT scans demonstrate the improved performance of the proposed method both from visual inspection of the images and a quantitative evaluation, compared to the widely used EM-ML algorithms. The dual estimation framework has the potential to be useful for estimating the attenuation map from emission data only and thus benefit the radioactivity reconstruction. PMID:25225796

  2. Geometric Characterization of Multi-Axis Multi-Pinhole SPECT

    PubMed Central

    DiFilippo, Frank P.

    2008-01-01

    A geometric model and calibration process are developed for SPECT imaging with multiple pinholes and multiple mechanical axes. Unlike the typical situation where pinhole collimators are mounted directly to rotating gamma ray detectors, this geometric model allows for independent rotation of the detectors and pinholes, for the case where the pinhole collimator is physically detached from the detectors. This geometric model is applied to a prototype small animal SPECT device with a total of 22 pinholes and which uses dual clinical SPECT detectors. All free parameters in the model are estimated from a calibration scan of point sources and without the need for a precision point source phantom. For a full calibration of this device, a scan of four point sources with 360° rotation is suitable for estimating all 95 free parameters of the geometric model. After a full calibration, a rapid calibration scan of two point sources with 180° rotation is suitable for estimating the subset of 22 parameters associated with repositioning the collimation device relative to the detectors. The high accuracy of the calibration process is validated experimentally. Residual differences between predicted and measured coordinates are normally distributed with 0.8 mm full width at half maximum and are estimated to contribute 0.12 mm root mean square to the reconstructed spatial resolution. Since this error is small compared to other contributions arising from the pinhole diameter and the detector, the accuracy of the calibration is sufficient for high resolution small animal SPECT imaging. PMID:18293574

  3. Nonlinear dual reconstruction of SPECT activity and attenuation images.

    PubMed

    Liu, Huafeng; Guo, Min; Hu, Zhenghui; Shi, Pengcheng; Hu, Hongjie

    2014-01-01

    In single photon emission computed tomography (SPECT), accurate attenuation maps are needed to perform essential attenuation compensation for high quality radioactivity estimation. Formulating the SPECT activity and attenuation reconstruction tasks as coupled signal estimation and system parameter identification problems, where the activity distribution and the attenuation parameter are treated as random variables with known prior statistics, we present a nonlinear dual reconstruction scheme based on the unscented Kalman filtering (UKF) principles. In this effort, the dynamic changes of the organ radioactivity distribution are described through state space evolution equations, while the photon-counting SPECT projection data are measured through the observation equations. Activity distribution is then estimated with sub-optimal fixed attenuation parameters, followed by attenuation map reconstruction given these activity estimates. Such coupled estimation processes are iteratively repeated as necessary until convergence. The results obtained from Monte Carlo simulated data, physical phantom, and real SPECT scans demonstrate the improved performance of the proposed method both from visual inspection of the images and a quantitative evaluation, compared to the widely used EM-ML algorithms. The dual estimation framework has the potential to be useful for estimating the attenuation map from emission data only and thus benefit the radioactivity reconstruction.

  4. Thallium-201 accumulation in cerebral candidiasis: Unexpected finding on SPECT

    SciTech Connect

    Tonami, N.; Matsuda, H.; Ooba, H.; Yokoyama, K.; Hisada, K.; Ikeda, K.; Yamashita, J. )

    1990-06-01

    The authors present an unexpected finding of Tl-201 uptake in the intracerebral lesions due to candidiasis. SPECT demonstrated the extent of the lesions and a high target-to-background ratio. The regions where abnormal Tl-201 accumulation was seen were nearly consistent with CT scans of those enhanced by a contrast agent. After treatment, most of the abnormal Tl-201 accumulation disappeared.

  5. Hemimegalencephaly: Clinical, EEG, neuroimaging, and IMP-SPECT correlation

    SciTech Connect

    Konkol, R.J.; Maister, B.H.; Wells, R.G.; Sty, J.R. )

    1990-11-01

    Iofetamine-single photon emission computed tomography (IMP-SPECT) was performed on 2 girls (5 1/2 and 6 years of age) with histories of intractable seizures, developmental delay, and unilateral hemiparesis secondary to hemimegalencephaly. Electroencephalography (EEG) revealed frequent focal discharges in 1 patient, while a nearly continuous burst suppression pattern over the malformed hemisphere was recorded in the other. IMP-SPECT demonstrated a good correlation with neuroimaging studies. In spite of the different EEG patterns, which had been proposed to predict contrasting clinical outcomes, both IMP-SPECT scans disclosed a similar decrease in tracer uptake in the malformed hemisphere. These results are consistent with the pattern of decreased tracer uptake found in other interictal studies of focal seizures without cerebral malformations. In view of recent recommendations for hemispherectomy in these patients, we suggest that the IMP-SPECT scan be used to compliment EEG as a method to define the extent of abnormality which may be more relevant to long-term prognosis than EEG alone.

  6. The aSPECT experiment - an overview and latest results

    NASA Astrophysics Data System (ADS)

    Schmidt, Christian; Aspect Collaboration

    2016-09-01

    The aSPECT retardation spectrometer measures the β- ν angular correlation coefficient a in free neutron β-decay. This measurement can be used to determine the ratio gA/gV of the weak coupling constants, as well as to search for physics beyond the Standard Model. In 2013 aSPECT had a successful beam time at the Institut Laue-Langevin. The goal of this beam time is to improve the current uncertainty of a from Δa / a 5 % to about 1%. The data analysis is in its final stage and nearly finished. In order to achieve an uncertainty of 1%, the systematics of aSPECT have to be understood accordingly. This is achieved by systematic tests and measurements of a with different parameter settings for the spectrometer during the beam time. Additionally, offline measurements have been performed to determine the effect on the systematics, e.g. work-function fluctuations of the electrodes. These measurements are used as input for on-going simulations of the spectrometer to understand and reduce the systematic uncertainties further. In this talk aSPECT will be introduced and the current status of the data analysis will be reported, including a preliminary error budget of the systematic uncertainties.

  7. Collimator design for a multipinhole brain SPECT insert for MRI

    SciTech Connect

    Van Audenhaege, Karen; Van Holen, Roel; Vanhove, Christian; Vandenberghe, Stefaan

    2015-11-15

    Purpose: Brain single photon emission computed tomography (SPECT) imaging is an important clinical tool, with unique tracers for studying neurological diseases. Nowadays, most commercial SPECT systems are combined with x-ray computed tomography (CT) in so-called SPECT/CT systems to obtain an anatomical background for the functional information. However, while CT images have a high spatial resolution, they have a low soft-tissue contrast, which is an important disadvantage for brain imaging. Magnetic resonance imaging (MRI), on the other hand, has a very high soft-tissue contrast and does not involve extra ionizing radiation. Therefore, the authors designed a brain SPECT insert that can operate inside a clinical MRI. Methods: The authors designed and simulated a compact stationary multipinhole SPECT insert based on digital silicon photomultiplier detector modules, which have shown to be MR-compatible and have an excellent intrinsic resolution (0.5 mm) when combined with a monolithic 2 mm thick LYSO crystal. First, the authors optimized the different parameters of the SPECT system to maximize sensitivity for a given target resolution of 7.2 mm in the center of the field-of-view, given the spatial constraints of the MR system. Second, the authors performed noiseless simulations of two multipinhole configurations to evaluate sampling and reconstructed resolution. Finally, the authors performed Monte Carlo simulations and compared the SPECT insert with a clinical system with ultrahigh-resolution (UHR) fan beam collimators, based on contrast-to-noise ratio and a visual comparison of a Hoffman phantom with a 9 mm cold lesion. Results: The optimization resulted in a stationary multipinhole system with a collimator radius of 150.2 mm and a detector radius of 172.67 mm, which corresponds to four rings of 34 diSPM detector modules. This allows the authors to include eight rings of 24 pinholes, which results in a system volume sensitivity of 395 cps/MBq. Noiseless simulations

  8. Characterization of the hot electron population with bremsstrahlung and backscatter measurements at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Albert, Felicie; Hohenberger, Matthias; Michel, Pierre; Divol, Laurent; Doeppner, Tilo; Dewald, Edward; Bachmann, Benjamin; Ralph, Joseph; Turnbull, David; Goyon, Clement; Thomas, Cliff; Landen, Otto; Moody, John

    2016-10-01

    In indirect-drive ignition experiments, the hot electron population, produced by laser-plasma interactions, can be inferred from the bremsstrahlung generated by the interaction of the hot electrons with the target. At the National Ignition Facility (NIF), the upgraded filter-fluorescer x-ray diagnostic (FFLEX), a 10-channel, time-resolved hard x-ray spectrometer operating in the 20- to 500-keV range, provides measurements of the bremsstrahlung spectrum. It typically shows a two-temperature distribution of the hot electron population inside the hohlraum. In SRS, where the laser is coupled to an electron plasma wave, the backscattered spectrum, measured with the NIF full-aperture backscatter system (FABS), is used to infer the plasma wave phase velocity. We will present FFLEX time-integrated and time-resolved measurements of the hot electron population low-temperature component. We will correlate them with electron plasma wave phase velocities inferred from FABS spectra for a range of recent shots performed at the National Ignition Facility. This work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  9. Formation region effects in transition radiation, bremsstrahlung, and ionization loss of ultrarelativistic electrons

    NASA Astrophysics Data System (ADS)

    Trofymenko, S. V.; Shul'ga, N. F.

    2016-11-01

    The processes of transition radiation and bremsstrahlung by an ultrarelativistic electron as well as the effect of transition radiation influence upon the electron ionization loss in thin layer of substance are theoretically investigated in the case when radiation formation region has macroscopically large size. Special attention is drawn to transition radiation (TR) generated during the traversal of thin metallic plate by the electron previously deflected from its initial direction of motion. In this case TR characteristics are calculated for realistic (circular) shape of the electron deflection trajectory. The difference of such characteristics under certain conditions from the ones obtained previously with the use of approximation of anglelike shape of the electron trajectory (instant deflection) is shown. The problem of measurement of bremsstrahlung characteristics in the prewave zone is investigated. The expressions defining the measured radiation distribution for arbitrary values of the size and the position of the detector used for radiation registration are derived. The problem of TR influence upon the electron ionization loss in thin plate and in a system of two plates is discussed. The proposal for experimental investigation of such effect is formulated.

  10. Initial studies of Bremsstrahlung energy deposition in small-bore superconducting undulator structures in linac environments

    SciTech Connect

    Cremer, T.; Tatchyn, R.

    1995-12-31

    One of the more promising technologies for developing minimal-length insertion devices for linac-driven, single-pass Free Electron Lasers (FELs) operating in the x-ray range is based on the use of superconducting (SC) materials. In recent FEL simulations, for example, a bifilar helical SC device with a 2 cm period and 1.8 T field was found to require a 30 m saturation length for operation at 1.5{Angstrom} on a 15 GeV linac, more than 40% shorter than an alternative hybrid/permanent magnet (hybrid/PM) undulator. AT the same time, however, SC technology is known to present characteristic difficulties for insertion device design, both in engineering detail and in operation. Perhaps the most critical problem, as observed, e.g., by Madey and co-workers in their initial FEL experiments, was the frequent quenching induced by scattered electrons upstream of their (bifilar) device. Postulating that this quenching was precipitated by directly-scattered or bremsstrahlung-induced particle energy deposited into the SC material or into material contiguous with it, the importance of numerical and experimental characterizations of this phenomenon for linac-based, user-facility SC undulator design becomes evident. In this paper we discuss selected prior experimental results and report on initial EGS4 code studies of scattered and bremsstrahlung induced particle energy deposition into SC structures with geometries comparable to a small-bore bifilar helical undulator.

  11. Experimental verification of dosimetry predictions of bremsstrahlung attenuation as a function of material and electron energy

    SciTech Connect

    Sanford, T.W.L.; Halbleib, J.A.; Beutler, D.E.; Knott, D.P.

    1993-05-01

    Dose attenuation with depth in an absorber of on-axis bremsstrahlung generated from an electron target is measured and shown to agree within {plus_minus}9% with Monte Carlo predictions as a function of absorber material (Al, Fe, Pb) and incident electron-beam energy (5.5--25.1 MeV). For this on-axis bremsstrahlung, 1 to 5 g/cm{sup 2} of upstream and 0.2 to 1 g/cm{sup 2} of downs Al buffer is sufficient to provide electron equilibration for CaF{sub 2}:Mn thermoluminescent dosimeter (TLDs) over the measured energy range of 5.5 to 25.1 MeV, respectively. Once ``effective`` equilibration has been established, an expression of the form DA/Q = C{sub 1}V{sup c{sub 2}}e{sup {minus}C}{sub 3}V{sup c}{sub 4}{ell}, can be used to predict the dose-area (DA) product per absorbed beam charge (Q) at a given incident beam energy (V) in TLDs as a function of depth ({ell}) in absorbers, within a fixed solid angle centered about the beam axis. This expression is quantified for the measurements presented here.

  12. Monochromatization of high-current nanosecond pulse source of x-ray bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Adischev, Y. N.; Afanasiev, K. V.; Vukolov, A. V.; Potylitsyn, Alexander P.

    2007-05-01

    The bremsstrahlung spectrum of the nanosecond electron accelerator on the basis of the vacuum diode supplied by the high-voltage nanosecond generator SINUS - 150 with the coaxial forming line combined with the transformer has been monochromatized by the tungsten crystal under the Bragg - geometry (θ B = 45 0). The dose field map has been taken by the dosimeter on the basis of the diamond detector in the median acceleration plane. The bremsstrahlung radiation beam divergence has left 62°. It has been shown that the maximum dose is 16 cGrey/s at the distance of 10 cm from the collector, then it falls down proportionally to the square of distance to the level less than 0.1 cGrey/s at the distance of 1 m. The X-Ray spectrum has been measured by the silicon semi-conductor X-ray spectrometer with energy resolution 280 eV for 5.9 keV. It has been shown that the two maximum at the spectrum corresponds the second and third orders of diffraction on (111) planes of a tungsten crystal.

  13. Analyzing power in pion-proton bremsstrahlung, and the. Delta. sup ++ (1232) magnetic moment

    SciTech Connect

    Bosshard, A.; Amsler, C.; Doebeli, M.; Doser, M.; Schaad, M.; Riedlberger, J.; Truoel, P. ); Bistirlich, J.A.; Crowe, K.M.; Ljungfelt, S.; Meyer, C.A. ); van den Brandt, B.; Konter, J.A.; Mango, S.; Renker, D. ); Loude, J.F.; Perroud, J.P. ); Haddock, R.P. ); Sober, D.I. )

    1991-10-01

    We report on a first measurement of the polarized-target asymmetry of the pion-proton bremsstrahlung cross section ({pi}{sup +}{ital p}{r arrow}{pi}{sup {minus}}{ital p}{gamma}). As in previous cross section measurements the pion energy (298 MeV) and the detector geometry for this experiment was chosen to optimize the sensitivity to the radiation from the magnetic dipole moment of the {Delta}{sup ++}(1232) resonance {mu}{sub {Delta}}. Comparison to a recent isobar model for pion-nucleon bremsstrahlung yields {mu}{sub {Delta}}=(1.62{plus minus}0.18){mu}{sub {ital p}}, where {mu}{sub {ital p}} is the proton magnetic moment. Since the asymmetry depends less than the cross section on the choice of the other input parameters for the model, their uncertainties affect this analysis by less than the experimental error. However the theory fails to represent both the cross section and the asymmetry data at the highest photon energies. Hence further improvements in the calculations are needed before the model dependence of the magnetic moment analysis can be fully assessed. The present result agrees with bag-model corrections to the SU(6) prediction {mu}{sub {Delta}}=2{mu}{sub {ital p}}. As a by-product, the analyzing power for elastic {pi}{sup +}{ital p} scattering at 415 MeV/{ital c} was also measured. This second result is in good agreement with phase shift calculations.

  14. Characterization of intense laser-produced fast electrons using hard x-rays via bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Sawada, H.; Sentoku, Y.; Bass, A.; Griffin, B.; Pandit, R.; Beg, F.; Chen, H.; McLean, H.; Link, A. J.; Patel, P. K.; Ping, Y.

    2015-11-01

    Energy distribution of high-power, short-pulse laser produced fast electrons was experimentally and numerically studied using high-energy bremsstrahlung x-rays. The hard x-ray photons and escaping electrons from various metal foils, irradiated by the 50 TW Leopard laser at Nevada Terawatt Facility, were recorded with a differential filter stack spectrometer that is sensitive to photons produced by mainly 0.5-2 MeV electrons and an electron spectrometer measuring >2 MeV electrons. The experimental bremsstrahlung and the slope of the measured escaped electrons were compared with an analytic calculation using an input electron spectrum estimated with the ponderomotive scaling. The result shows that the electron spectrum entering a Cu foil could be continuous single slope with the slope temperature of ˜1.5 MeV in the detector range. The experiment and analytic calculation were then compared with a 2D particle-in-cell code, PICLS, including a newly developed radiation transport module. The simulation shows that a two-temperature electron distribution is generated at the laser interaction region, but only the hot component of the fast electrons flow into the target during the interaction because the low energy electron component is trapped by self-generated magnetic field in the preformed plasma. A significant amount of the photons less than 100 keV observed in the experiment could be attributed to the low energy electrons entering the foil a few picoseconds later after the gating field disappears.

  15. Analysis of Fast Electron Energy Distribution by Measuring Hard X-ray Bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Daykin, Tyler; Sawada, Hiroshi; Sentoku, Yasuhiko; Bass, Anthony; Griffin, Brandon; Pandit, Rishi; Beg, Farhat; Chen, Hui; McLean, Harry; Link, Anthony; Patel, Prav; Ping, Yuan

    2015-11-01

    Characterization of intense, short-pulse laser-produced fast electrons is important for fundamental understanding and applications. We carried out an experiment to characterize the fast electron energy distribution by measuring angular-dependent high-energy bremsstrahlung x-rays. A 100 μm thick metal foil (Al, Cu, and Ag) mounted on a plastic backing was irradiated by the 0.35 ps, 15 J Leopard Laser at the Nevada Terawatt Facility. The bremsstrahlung x-rays and the escaping electrons from the target were recorded using differential filter stack spectrometers at 22° and 45° off laser axis and a magnet-based electron spectrometer along the laser axis. The electron spectrum inferred from two different diagnostics had single slope temperature of ~ 1.5 MeV for the Cu foil. The results were compared to an analytic calculation and a 2-D Particle-in-cell code, PICLS. The analysis of the electron energy distribution and angular distribution will be presented. This work was supported by the UNR Office of the Provost and by DOE/OFES under Contract No. DE-SC0008827. This collaborative work was partially supported under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Con.

  16. Dealing with Cerenkov radiation generated in organic scintillator dosimeters by bremsstrahlung beams

    NASA Astrophysics Data System (ADS)

    Clift, M. A.; Sutton, R. A.; Webb, D. V.

    2000-05-01

    An organic scintillator detector system has been developed for radiotherapy bremsstrahlung dosimetry. The scintillators are connected to photodiodes by light pipes as the photodiodes must be removed and shielded from the incident radiation. The photodiodes see visible and near-visible light emissions from the scintillator as well as Cerenkov and fluorescence radiation that has been generated and trapped in the scintillator and light pipe. The Cerenkov and fluorescence radiation limits the accuracy of the dosimeter. This work examines a range of methods for diminishing the signal contribution of Cerenkov and fluorescence radiation while optimizing the scintillator signal. Three methods of achieving these goals have been used. They are: reflective coatings on the scintillator, long-wavelength-emitting scintillators used in conjunction with the photodiode, and absorptive filters placed between the light guide and photodiode. The contribution of the Cerenkov radiation to the light seen by the photodiode has been modelled and the model predictions have been tested using bremsstrahlung beams of peak energy between 13 and 20 MV, showing agreement with measurement.

  17. Effect of degenerate particles on internal bremsstrahlung of Majorana dark matter

    NASA Astrophysics Data System (ADS)

    Okada, Hiroshi; Toma, Takashi

    2015-11-01

    Gamma-rays induced by annihilation or decay of dark matter can be its smoking gun signature. In particular, gamma-rays generated by internal bremsstrahlung of Majorana and real scalar dark matter is promising since it can be a leading emission of sharp gamma-rays. However in the case of Majorana dark matter, its cross section for internal bremsstrahlung cannot be large enough to be observed by future gamma-ray experiments if the observed relic density is assumed to be thermally produced. In this paper, we introduce some degenerate particles with Majorana dark matter, and show they lead enhancement of the cross section. As a result, increase of about one order of magnitude for the cross section is possible without conflict with the observed relic density, and it would be tested by the future gamma-ray experiments such as GAMMA-400 and Cherenkov Telescope Array (CTA). In addition, the constraints of perturbativity, positron observation by the AMS experiment and direct search for dark matter are discussed.

  18. Advanced reconstruction of attenuation maps using SPECT emission data only

    NASA Astrophysics Data System (ADS)

    Salomon, André; Goedicke, Andreas; Aach, Til

    2009-02-01

    Today, attenuation corrected SPECT, typically performed using CT or Gadolinium line source based transmission scans, is more and more becoming standard in many medical applications. Moreover, the information about the material density distribution provided by these scans is key for other artifact compensation approaches in advanced SPECT reconstruction. Major drawbacks of these approaches are the additional patient radiation and hardware/maintenance costs as well as the additional workflow effort, e.g. if the CT scans are not performed on a hybrid scanner. It has been investigated in the past, whether it is possible to recover this structural information solely from the SPECT scan data. However, the investigated methods often result in noticeable image artifacts due to cross-dependences between attenuation and activity distribution estimation. With the simultaneous reconstruction method presented in this paper, we aim to effectively prevent these typical cross-talk artifacts using a-priori known atlas information of a human body. At first, an initial 3D shape model is coarsely registered to the SPECT data using anatomical landmarks and each organ structure within the model is identified with its typical attenuation coefficient. During the iterative reconstruction based on a modified ML-EM scheme, the algorithm simultaneously adapts both, the local activity estimation and the 3D shape model in order to improve the overall consistency between measured and estimated sinogram data. By explicitly avoiding topology modifications resulting in a non-anatomical state, we ensure that the estimated attenuation map remains realistic. Several tests with simulated as well as real patient SPECT data were performed to test the proposed algorithm, which demonstrated reliable convergence behaviour in both cases. Comparing the achieved results with available reference data, an overall good agreement for both cold as well as hot activity regions could be observed (mean deviation: -5.98%).

  19. Comparison of planar and SPECT thallium imaging in men and women

    SciTech Connect

    Links, J.M.; Fintel, D.F.; Becker, L.C.; Wagner, H.N. Jr.

    1985-05-01

    The authors studied the overall accuracy of planar and SPECT Tl imaging in the diagnosis of coronary artery disease (CAD) in 85 subjects (65 males, 20 females; 52 with angiographic CAD, 33 without CAD), and then separately analyzed men and women to see if factors such as breast attenuation significantly alter the accuracy. All subjects were exercised to symptom-limit or peak heart rate achievement, and injected with 2 mCi Tl-201. Planar and SPECT stress studies were acquired in a random order, with delayed studies acquired 3 hours after injection. The studies were viewed in a blinded, random order, and interpreted on a 5 point scale by consensus of 3 observers (1: definitely normal, 2: probably normal, 3: equivocal, 4: probably abnormal, 5: definitely abnormal). Receiver operating characteristic (ROC) curves were constructed for overall planar and SPECT, and then separately for male planar, male SPECT, female planar, female SPECT. The overall SPECT curve was above the overall planar curve. The overall SPECT curve was above the overall planar curve. At a specificity of 90%, SPECT sensitivity was 93%, planar was 80%. For both males and females, the SPECT curves were above the planar curves. However, both planar and SPECT male curves were above both female curves. At a specificity of 90%, sensitivities were male planar, 83%; male SPECT, 97%; female planar, 50%; female SPECT, 80%. This difference in accuracy between males and females was not due to adequacy of exercise (peak exercise heart rate in CAD pts: males, 145 +- 28 bpm; females, 151 +- 28; p=NS; in normals: 178 bpm for both males and females). SPECT is more accurate than planar imaging in the diagnosis of CAD. However, differences in accuracy exist between men and women, which may be due to breast attenuation.

  20. Discrepancies in brain perfusion SPECT findings between Tc-99m HMPAO and Tc-99m ECD: evaluation using dynamic SPECT in patients with hyperemia.

    PubMed

    Miyazawa, N; Koizumi, K; Mitsuka, S; Nukui, H

    1998-10-01

    Discrepancies have been reported between the findings of Tc-99m HMPAO and Tc-99m ECD brain perfusion SPECT imaging. This study investigated the discrepancies in the accumulation of these tracers using dynamic SPECT to detect the super early phase of distribution. Thirteen patients with luxury perfusion or high flow states were studied with both dynamic and standard SPECT using Tc-99m HMPAO and Tc-99m ECD within 1-3 days. Standard SPECT showed discrepancies in 6 of 13 patients. Patients with meningioma and cerebral thrombosis had increased accumulation of Tc-99m HMPAO and decreased uptake of Tc-99m ECD. Patients with arteriovenous malformation, subarachnoid hemorrhage, and cavernous angioma had decreased accumulation of both tracers, but to different degrees. Dynamic SPECT showed increased or normal accumulation (i.e., essentially no discrepancy) in the first few minutes. However, Tc-99m HMPAO had a longer retention time than Tc-99m ECD in the ensuing 5-10 minutes. Dynamic SPECT revealed a similar accumulation pattern but different washout rates for the two tracers. Tc-99m HMPAO might be a more suitable tracer to detect high flow states or luxury perfusion because the findings on standard SPECT were more in agreement with those of dynamic SPECT using this tracer.

  1. Activity concentration measurements using a conjugate gradient (Siemens xSPECT) reconstruction algorithm in SPECT/CT.

    PubMed

    Armstrong, Ian S; Hoffmann, Sandra A

    2016-11-01

    The interest in quantitative single photon emission computer tomography (SPECT) shows potential in a number of clinical applications and now several vendors are providing software and hardware solutions to allow 'SUV-SPECT' to mirror metrics used in PET imaging. This brief technical report assesses the accuracy of activity concentration measurements using a new algorithm 'xSPECT' from Siemens Healthcare. SPECT/CT data were acquired from a uniform cylinder with 5, 10, 15 and 20 s/projection and NEMA image quality phantom with 25 s/projection. The NEMA phantom had hot spheres filled with an 8 : 1 activity concentration relative to the background compartment. Reconstructions were performed using parameters defined by manufacturer presets available with the algorithm. The accuracy of activity concentration measurements was assessed. A dose calibrator-camera cross-calibration factor (CCF) was derived from the uniform phantom data. In uniform phantom images, a positive bias was observed, ranging from ∼6% in the lower count images to ∼4% in the higher-count images. On the basis of the higher-count data, a CCF of 0.96 was derived. As expected, considerable negative bias was measured in the NEMA spheres using region mean values whereas positive bias was measured in the four largest NEMA spheres. Nonmonotonically increasing recovery curves for the hot spheres suggested the presence of Gibbs edge enhancement from resolution modelling. Sufficiently accurate activity concentration measurements can easily be measured on images reconstructed with the xSPECT algorithm without a CCF. However, the use of a CCF is likely to improve accuracy further. A manual conversion of voxel values into SUV should be possible, provided that the patient weight, injected activity and time between injection and imaging are all known accurately.

  2. A methodology for generating normal and pathological brain perfusion SPECT images for evaluation of MRI/SPECT fusion methods: application in epilepsy

    NASA Astrophysics Data System (ADS)

    Grova, C.; Jannin, P.; Biraben, A.; Buvat, I.; Benali, H.; Bernard, A. M.; Scarabin, J. M.; Gibaud, B.

    2003-12-01

    Quantitative evaluation of brain MRI/SPECT fusion methods for normal and in particular pathological datasets is difficult, due to the frequent lack of relevant ground truth. We propose a methodology to generate MRI and SPECT datasets dedicated to the evaluation of MRI/SPECT fusion methods and illustrate the method when dealing with ictal SPECT. The method consists in generating normal or pathological SPECT data perfectly aligned with a high-resolution 3D T1-weighted MRI using realistic Monte Carlo simulations that closely reproduce the response of a SPECT imaging system. Anatomical input data for the SPECT simulations are obtained from this 3D T1-weighted MRI, while functional input data result from an inter-individual analysis of anatomically standardized SPECT data. The method makes it possible to control the 'brain perfusion' function by proposing a theoretical model of brain perfusion from measurements performed on real SPECT images. Our method provides an absolute gold standard for assessing MRI/SPECT registration method accuracy since, by construction, the SPECT data are perfectly registered with the MRI data. The proposed methodology has been applied to create a theoretical model of normal brain perfusion and ictal brain perfusion characteristic of mesial temporal lobe epilepsy. To approach realistic and unbiased perfusion models, real SPECT data were corrected for uniform attenuation, scatter and partial volume effect. An anatomic standardization was used to account for anatomic variability between subjects. Realistic simulations of normal and ictal SPECT deduced from these perfusion models are presented. The comparison of real and simulated SPECT images showed relative differences in regional activity concentration of less than 20% in most anatomical structures, for both normal and ictal data, suggesting realistic models of perfusion distributions for evaluation purposes. Inter-hemispheric asymmetry coefficients measured on simulated data were found within

  3. A methodology for generating normal and pathological brain perfusion SPECT images for evaluation of MRI/SPECT fusion methods: application in epilepsy.

    PubMed

    Grova, C; Jannin, P; Biraben, A; Buvat, I; Benali, H; Bernard, A M; Scarabin, J M; Gibaud, B

    2003-12-21

    Quantitative evaluation of brain MRI/SPECT fusion methods for normal and in particular pathological datasets is difficult, due to the frequent lack of relevant ground truth. We propose a methodology to generate MRI and SPECT datasets dedicated to the evaluation of MRI/SPECT fusion methods and illustrate the method when dealing with ictal SPECT. The method consists in generating normal or pathological SPECT data perfectly aligned with a high-resolution 3D T1-weighted MRI using realistic Monte Carlo simulations that closely reproduce the response of a SPECT imaging system. Anatomical input data for the SPECT simulations are obtained from this 3D T1-weighted MRI, while functional input data result from an inter-individual analysis of anatomically standardized SPECT data. The method makes it possible to control the 'brain perfusion' function by proposing a theoretical model of brain perfusion from measurements performed on real SPECT images. Our method provides an absolute gold standard for assessing MRI/SPECT registration method accuracy since, by construction, the SPECT data are perfectly registered with the MRI data. The proposed methodology has been applied to create a theoretical model of normal brain perfusion and ictal brain perfusion characteristic of mesial temporal lobe epilepsy. To approach realistic and unbiased perfusion models, real SPECT data were corrected for uniform attenuation, scatter and partial volume effect. An anatomic standardization was used to account for anatomic variability between subjects. Realistic simulations of normal and ictal SPECT deduced from these perfusion models are presented. The comparison of real and simulated SPECT images showed relative differences in regional activity concentration of less than 20% in most anatomical structures, for both normal and ictal data, suggesting realistic models of perfusion distributions for evaluation purposes. Inter-hemispheric asymmetry coefficients measured on simulated data were found within

  4. Secondary bremsstrahlung and the energy-conservation aspects of kerma in photon-irradiated media

    NASA Astrophysics Data System (ADS)

    Kumar, Sudhir; Nahum, Alan E.

    2016-02-01

    Kerma, collision kerma and absorbed dose in media irradiated by megavoltage photons are analysed with respect to energy conservation. The user-code DOSRZnrc was employed to compute absorbed dose D, kerma K and a special form of kerma, K ncpt, obtained by setting the charged-particle transport energy cut-off very high, thereby preventing the generation of ‘secondary bremsstrahlung’ along the charged-particle paths. The user-code FLURZnrc was employed to compute photon fluence, differential in energy, from which collision kerma, K col and K were derived. The ratios K/D, K ncpt/D and K col/D have thereby been determined over a very large volumes of water, aluminium and copper irradiated by broad, parallel beams of 0.1 to 25 MeV monoenergetic photons, and 6, 10 and 15 MV ‘clinical’ radiotherapy qualities. Concerning depth-dependence, the ‘area under the kerma, K, curve’ exceeded that under the dose curve, demonstrating that kerma does not conserve energy when computed over a large volume. This is due to the ‘double counting’ of the energy of the secondary bremsstrahlung photons, this energy being (implicitly) included in the kerma ‘liberated’ in the irradiated medium, at the same time as this secondary bremsstrahlung is included in the photon fluence which gives rise to kerma elsewhere in the medium. For 25 MeV photons this ‘violation’ amounts to 8.6%, 14.2% and 25.5% in large volumes of water, aluminium and copper respectively but only 0.6% for a ‘clinical’ 6 MV beam in water. By contrast, K col/D and K ncpt/D, also computed over very large phantoms of the same three media, for the same beam qualities, are equal to unity within (very low) statistical uncertainties, demonstrating that collision kerma and the special type of kerma, K ncpt, do conserve energy over a large volume. A comparison of photon fluence spectra for the 25 MeV beam at a depth of  ≈51 g cm-2 for both very high and very low charged-particle transport cut

  5. EANM procedural guidelines for radionuclide myocardial perfusion imaging with SPECT and SPECT/CT: 2015 revision.

    PubMed

    Verberne, Hein J; Acampa, Wanda; Anagnostopoulos, Constantinos; Ballinger, Jim; Bengel, Frank; De Bondt, Pieter; Buechel, Ronny R; Cuocolo, Alberto; van Eck-Smit, Berthe L F; Flotats, Albert; Hacker, Marcus; Hindorf, Cecilia; Kaufmann, Philip A; Lindner, Oliver; Ljungberg, Michael; Lonsdale, Markus; Manrique, Alain; Minarik, David; Scholte, Arthur J H A; Slart, Riemer H J A; Trägårdh, Elin; de Wit, Tim C; Hesse, Birger

    2015-11-01

    Since the publication of the European Association of Nuclear Medicine (EANM) procedural guidelines for radionuclide myocardial perfusion imaging (MPI) in 2005, many small and some larger steps of progress have been made, improving MPI procedures. In this paper, the major changes from the updated 2015 procedural guidelines are highlighted, focusing on the important changes related to new instrumentation with improved image information and the possibility to reduce radiation exposure, which is further discussed in relation to the recent developments of new International Commission on Radiological Protection (ICRP) models. Introduction of the selective coronary vasodilator regadenoson and the use of coronary CT-contrast agents for hybrid imaging with SPECT/CT angiography are other important areas for nuclear cardiology that were not included in the previous guidelines. A large number of minor changes have been described in more detail in the fully revised version available at the EANM home page: http://eanm.org/publications/guidelines/2015_07_EANM_FINAL_myocardial_perfusion_guideline.pdf .

  6. Design and simulation of a high-resolution stationary SPECT system for small animals

    NASA Astrophysics Data System (ADS)

    Beekman, Freek J.; Vastenhouw, Brendan

    2004-10-01

    Exciting new SPECT systems can be created by combining pinhole imaging with compact high-resolution gamma cameras. These new systems are able to solve the problem of the limited sensitivity-resolution trade-off that hampers contemporary small animal SPECT. The design presented here (U-SPECT-III) uses a set of detectors placed in a polygonal configuration and a cylindrical collimator that contains 135 pinholes arranged in nine rings. Each ring contains 15 gold pinhole apertures that focus on the centre of the cylinder. A non-overlapping projection is acquired via each pinhole. Consequently, when a mouse brain is placed in the central field-of-view, each voxel in the cerebrum can be observed via 130 to 135 different pinholes simultaneously. A method for high-resolution scintillation detection is described that eliminates the depth-of-interaction problem encountered with pinhole cameras, and is expected to provide intrinsic detector resolutions better than 150 µm. By means of simulations U-SPECT-III is compared to a simulated dual pinhole SPECT (DP-SPECT) system with a pixelated array consisting of 2.0 × 2.0 mm NaI crystals. Analytic calculations indicate that the proposed U-SPECT-III system yields an almost four times higher linear and about sixty times higher volumetric system resolution than DP-SPECT, when the systems are compared at matching system sensitivity. In addition, it should be possible to achieve a 15 up to 30 times higher sensitivity with U-SPECT-III when the systems are compared at equal resolution. Simulated images of a digital mouse-brain phantom show much more detail with U-SPECT-III than with DP-SPECT. In a resolution phantom, 0.3 mm diameter cold rods are clearly visible with U-SPECT-III, whereas with DP-SPECT the smallest visible rods are about 0.6-0.8 mm. Furthermore, with U-SPECT-III, the image deformations outside the central plane of reconstruction that hamper conventional pinhole SPECT are strongly suppressed. Simulation results indicate

  7. Potential value of serial cerebral SPECT scanning in the evaluation of psychiatric illness

    SciTech Connect

    Notardonato, H.; Gonzalez-Avilez, A.; Van Heertum, R.L.; O'Connell, R.A.; Yudd, A.P.

    1989-05-01

    Cerebral SPECT imaging has the potential to make an important contribution to clinical psychiatry. Cerebral SPECT scanning, stimulated by the work with PET, is readily available and much less expensive than PET. This paper reports a case demonstrating the potential value of cerebral SPECT scanning with I-123 IMP, specifically in the serial evaluation of a schizophrenic patient with auditory hallucinations. The initial scan revealed focal areas of increased uptake in the caudate nuclei of the basal ganglia, and in the right temporal lobe. After pharmacological treatment with clinical improvement, the follow-up SPECT scan demonstrated significant improvement in the distribution of the radiopharmaceutical.

  8. Double Higgs-boson bremsstrahlung from W and Z bosons at supercolliders

    NASA Astrophysics Data System (ADS)

    Barger, V.; Han, T.; Phillips, R. J. N.

    1988-11-01

    We calculate the production of two standard-model neutral Higgs bosons via bremsstrahlung from a single W or Z boson in pp or e+e- collisions at supercollider energies. Observation of these processes would test the predicted HHH, HVV, and HHVV couplings (V=W or Z). For e+e--->ZHH we extend previous cross-section calculations to a more comprehensive range of energies and Higgs-boson masses, that may be accessible to future machines; we also give final-particle distributions. In the pp case we present the first calculations of the processes pp-->HHVX the cross sections are comparable to other double Higgs-boson production processes for a range of energies and masses. The presence of W or Z accompanying the Higgs-boson pair has distinct practical advantages for triggering and for separating the final state from backgrounds.

  9. Double Higgs-boson bremsstrahlung from W and Z bosons at supercolliders

    SciTech Connect

    Barger, V.; Han, T.; Phillips, R.J.N.

    1988-11-01

    We calculate the production of two standard-model neutral Higgs bosons via bremsstrahlung from a single W or Z boson in pp or e/sup +/e/sup -/ collisions at supercollider energies. Observation of these processes would test the predicted HHH, HVV, and HHVV couplings (V = W or Z). For e/sup +/e/sup -/..-->..ZHH we extend previous cross-section calculations to a more comprehensive range of energies and Higgs-boson masses, that may be accessible to future machines; we also give final-particle distributions. In the pp case we present the first calculations of the processes pp..-->..HHVX; the cross sections are comparable to other double Higgs-boson production processes for a range of energies and masses. The presence of W or Z accompanying the Higgs-boson pair has distinct practical advantages for triggering and for separating the final state from backgrounds.

  10. Thick-target bremsstrahlung interpretation of short time-scale solar hard X-ray features

    NASA Technical Reports Server (NTRS)

    Emslie, A. G.

    1983-01-01

    Steady-state analyses of bremsstrahlung hard X-ray production in solar flares are appropriate only if the lifetime of the high energy electrons in the X-ray source is much shorter than the duration of the observed X-ray burst. For a thick-target nonthermal model, this implies that a full time-dependent analysis is required when the duration of the burst is comparable to the collisional lifetime of the injected electrons, in turn set by the lengths and densities of the flaring region. In this paper we present the results of such a time-dependent analysis, and we point out that the intrinsic temporal signature of the thick-target production mechanism, caused by the finite travel time of the electrons through the target, may indeed rule out such a mechanism for extremely short duration hard X-ray events.

  11. Efficient far-infrared thermal bremsstrahlung radiation from a heterojunction bipolar transistor

    SciTech Connect

    Chung, Pei-Kang; Yen, Shun-Tung

    2015-08-28

    We investigate the far-infrared thermal radiation properties of a heterojunction bipolar transistor. The device conveniently provides a high electric field for electrons to heat the lattice and the electron gas in a background with ions embedded. Because of very high effective temperature of the electron gas in the collector, the electron-ion bremsstrahlung makes efficient the thermal radiation in the far-infrared region. The transistor can yield a radiation power of 0.1 mW with the spectral region between 2 and 75 THz and a power conversion efficiency of 6 × 10{sup −4}. Such output contains a power of 20 μW in the low-frequency part (2–20 THz) of the spectrum.

  12. Potential enhancement of warm X-ray dose from a reflexing bremsstrahlung diode

    SciTech Connect

    Sanford, T.W.L.; Halbleib, J.A.; Cooperstein, G.

    1995-08-01

    The potential for generating intense bursts of warm x rays (20 to 60 keV) using electron reflexing diodes on pulsed-power accelerators is evaluated with the TIGER Monte Carlo code, showing that hundreds of kilojoules of warm x rays can be generated under idealized conditions, for a Jupiter (60-MA, 5-MV, 100-ns) class accelerator. The calculations are compared with data from Gamble-II experiments and applied to two suggested Jupiter diode configurations. If the simultaneous irradiation from the high-energy tail of the bremsstrahlung, which accompanies the warm x rays, is a concern then the reflexing technique is shown to be limited to the irradiation of targets thinner than {approximately}400 {mu}m for low-Z targets like aluminum and thinner than {approximately}5 {mu}m for high-Z targets like gold.

  13. Potential enhancement of warm x-ray dose from a reflexing bremsstrahlung diode

    SciTech Connect

    Sanford, T.W.L.; Halbleib, J.A.; Cooperstein, G.; Weber, B.V.

    1995-07-01

    The potential for generating intense bursts of war x rays (20 to 60 keV) using electron reflexing diodes on pulsed-power accelerators is evaluated with the TIGER Monte Carlo code, showing that hundreds of kilojoules of warm x rays can be generated under idealized conditions. The calculation are compared with data from Gamble-II experiments and applied to two suggest Jupiter (60-MA, 5-MV, 100-ns) diode configurations. If the simultaneous irradiation from the high-energy tail of the bremsstrahlung which accompanies the warm x rays is a concern, then the reflexing technique is shown to be limited to the irradiation of targets thinner than {approximately} 400 {mu}m for low-Z targets like aluminum and thinner than {approximately} 5 {mu}m for high-Z targets like gold.

  14. Threshold and spin factors in the yield of bremsstrahlung-induced reactions

    SciTech Connect

    Karamian, S. A.

    2013-12-15

    Relative yields of photon-induced reactions are systematized in a function of the threshold parameter for moderately heavy targets at the bremsstrahlung end-point energy lower than 30 MeV. Regular dependence is established for the group of (γ, n), (γ, p), and (γ, d) reactions, while the yields of (γ, 2n) and (γ,α) reactions deviate from the regularity. Physical conclusions are discussed and possible application of this systematic for data processing is proposed. In particular, the constituent threshold and spin factors in the isomer-to-ground-state ratio could be isolated separately. For spin dependence of the yields, a new regularization parameter is introduced and previously hidden peculiarities are concluded.

  15. The effect of the {Delta} excitation on proton-proton bremsstrahlung

    SciTech Connect

    Lee, T.S.H.; Jong, F. de; Nakayama, K.

    1995-08-01

    The proton-proton bremsstrahlung is investigated with a coupled-channel model with {pi} and {Delta} degrees of freedom. The model is consistent with the NN scattering up to 1 GeV and the {gamma}N{Delta} vertex determined in the study of pion photoproduction on the nucleon. We find that the {Delta} excitation can significantly improve the agreement with the pp {yields} pp{gamma} data at E{sub L} = 280 MeV. The N{Delta} rescattering plays an important role in determining the angular distribution and analyzing powers. Predictions at E{sub L} = 550 and 800 MeV were made for the forthcoming experimental tests at COSY of Juelich. A paper describing our results was submitted for publication.

  16. Simulation of medical electron linac bremsstrahlung beam transport in typical shielding materials.

    PubMed

    Avila-Rodriguez, Miguel A; DeLuca, Paul M; Bohm, Tim D

    2005-01-01

    The Monte Carlo N-particle code MCNP version 4C3 was used to investigate the backscattering and transmission of high-energy photons in concrete, iron and lead at deep penetration. A typical bremsstrahlung beam from a 24 MV linac was used, and the transmission up to 15 mean-free paths was studied. Broad beam slab geometry was used. Estimates of the transmission in terms of absorbed dose to tissue ratio and air kerma ratio were performed for the primary and secondary components of the transmitted beam in the three materials. The tissue dose and air kerma buildup factors were calculated and fitted to Berger's equation. Finally, the differential dose albedo values for common reflected angles were determined.

  17. Search for a 17 keV neutrino in the internal bremsstrahlung spectrum of 125I

    NASA Astrophysics Data System (ADS)

    Hindi, M. M.; Kozub, R. L.; Robinson, S. J.

    1994-06-01

    We have searched for evidence of the emission of a 17 keV neutrino in the internal bremsstrahlung (IB) spectrum accompanying the electron capture decay of 125I. The IB spectrum, recorded in a planar Ge detector, has 1.2×106 counts per keV at 17 keV below the 2p end point. We set an upper limit of 0.4% for the admixture of a 17 keV neutrino, at the 90% confidence level, and exclude a 0.8% admixture at the 99.6% confidence level. The QEC value is found to be 185.77+/-0.06 keV. We also find that the recent calculations of Surić et al., which employ relativistic self-consistent-field atomic wave functions, reproduce the shape and relative intensity of IB partial spectra within a few percent.

  18. Application of visible bremsstrahlung to Z{sub eff} measurement on the Experimental Advanced Superconducting Tokamak

    SciTech Connect

    Chen, Yingjie; Wu, Zhenwei; Gao, Wei; Ti, Ang; Zhang, Ling; Jie, Yinxian; Zhang, Jizong; Huang, Juan; Xu, Zong; Zhao, Junyu

    2015-02-15

    The multi-channel visible bremsstrahlung measurement system has been developed on Experimental Advanced Superconducting Tokamak (EAST). In addition to providing effective ion charge Z{sub eff} as a routine diagnostic, this diagnostic can also be used to estimate other parameters. With the assumption that Z{sub eff} can be seen as constant across the radius and does not change significantly during steady state discharges, central electron temperature, averaged electron density, electron density profile, and plasma current density profile have been obtained based on the scaling of Z{sub eff} with electron density and the relations between Z{sub eff} and these parameters. The estimated results are in good coincidence with measured values, providing an effective and convenient method to estimate other plasma parameters.

  19. Modeling Relativistic Electron Precipitation Bremsstrahlung X-Ray Intensities at 10-100 km Manned Vehicle Altitudes

    NASA Technical Reports Server (NTRS)

    Krause, L. Habsh; Gilchrist, B. E.; Nishikawa, Ken-Ichi

    2013-01-01

    Relativisitic electron precipitation (REP) events occur when beams or bunches of relativistic electrons of magnetospheric origin enter the Earth's atmosphere, typically at auroral latitudes. REP events are associated with a variety of space weather effects, including production of transitional and bremsstrahlung radiation, catalytic depletion of stratospheric ozone, and scintillation of transionospheric radio waves. This study examines the intensities of x-rays produced at airliner, manned balloon, and space reuseable launch vehicles (sRLVs). The monoenergetic beam is modeled in cylindrical symetry using the paraxial ray equation. Bremsstrahlung photon production is calculated using the traditional Sauter-Elwert cross-section, providing x-ray emission spectra differential in energy and angle. Attenuation is computed for a plane-stratified standard atmosphere, and the loss processes include photoionization, Rayleigh and Compton scattering, electron-positron pair production, and photonuclear interaction. Peak altitudes of electron energy deposition and bremsstrahlung x-ray production were calculated for beams of energies from 1 MeV through 100 MeV. The altitude peak of bremsstrahlung deposition was consistently and significantly lower that that of the electron deposition due to the longer mean free paths of x-rays compared to electrons within the atmosphere. For example, for a nadir-directed monoenergetic 5 MeV beam, the peak deposition altitude was calculated to be 42 km, but the resulting bremsstrahlung deposition peaked at 25 km. This has implications for crew and passenger safety, especially with the growth of the space tourism industry. A survey of results covering the 1-100 MeV spectrum for the three altitude ranges of interest will be presented.

  20. SPECT study of regional cerebral blood flow in Alzheimer disease

    SciTech Connect

    Bonte, F.J.; Ross, E.D.; Chehabi, H.H.; Devous, M.D. Sr.

    1986-07-01

    A common cause of dementia in late midlife and old age is Alzheimer disease (AD), which affects more than one in 20 individuals over the age of 65. Past studies of regional cerebral blood flow (rCBF) in patients with AD here suggested blood flow abnormalities, but findings have differed. We have studied 37 patients diagnosed as having AD with inhalation and washout of /sup 133/Xe and single-photon emission computed tomography (SPECT), obtaining evidence of abnormal rCBF patterns in 19. Flow reductions were most common in the temporoparietal regions and were occasionally found in the frontal areas. Investigators using positron-emission tomography (PET) have identified similar findings with respect to rCBF and regional oxygen, glucose, and protein metabolism. The SPECT determination of rCBF, which gives information similar to that provided by PET, may assume importance in the diagnosis of AD and in the differential diagnosis of the dementias.

  1. Delayed redistribution in thallium 201 SPECT myocardial perfusion studies

    SciTech Connect

    Ziessman, H.A.; Keyes, J.W. Jr.; Fox, L.M.; Green, C.E.; Fox, S.M. )

    1989-11-01

    Stress {sup 201}Tl myocardial perfusion studies are useful in differentiating viable, reversibly ischemic from infarcted myocardium. A perfusion defect that shows redistribution 2 to 4 h after {sup 201}Tl injection is diagnostic of ischemia, while a fixed defect suggests infarction. However, occasional patients with a fixed defect at 4 h have redistribution at 24 h. This study evaluates the frequency and significance of this delayed redistribution with SPECT {sup 201}Tl. Patients with either no or incomplete redistribution at 4 h had repeat imaging 18 to 48 h later. Delayed redistribution was seen in 8/26 (31 percent). Four had incomplete and four had no redistribution at 4 h. Delayed redistribution with SPECT {sup 201}Tl is more common than generally appreciated, and we recommend delayed images in patients with fixed perfusion defects or incomplete redistribution at 4-h imaging, particularly in patients with previous infarctions for whom a revascularization procedure is being considered.

  2. Accuracy of quantitative reconstructions in SPECT/CT imaging

    NASA Astrophysics Data System (ADS)

    Shcherbinin, S.; Celler, A.; Belhocine, T.; van der Werf, R.; Driedger, A.

    2008-09-01

    The goal of this study was to determine the quantitative accuracy of our OSEM-APDI reconstruction method based on SPECT/CT imaging for Tc-99m, In-111, I-123, and I-131 isotopes. Phantom studies were performed on a SPECT/low-dose multislice CT system (Infinia-Hawkeye-4 slice, GE Healthcare) using clinical acquisition protocols. Two radioactive sources were centrally and peripherally placed inside an anthropometric Thorax phantom filled with non-radioactive water. Corrections for attenuation, scatter, collimator blurring and collimator septal penetration were applied and their contribution to the overall accuracy of the reconstruction was evaluated. Reconstruction with the most comprehensive set of corrections resulted in activity estimation with error levels of 3-5% for all the isotopes.

  3. Infective endocarditis detection through SPECT/CT images digital processing

    NASA Astrophysics Data System (ADS)

    Moreno, Albino; Valdés, Raquel; Jiménez, Luis; Vallejo, Enrique; Hernández, Salvador; Soto, Gabriel

    2014-03-01

    Infective endocarditis (IE) is a difficult-to-diagnose pathology, since its manifestation in patients is highly variable. In this work, it was proposed a semiautomatic algorithm based on SPECT images digital processing for the detection of IE using a CT images volume as a spatial reference. The heart/lung rate was calculated using the SPECT images information. There were no statistically significant differences between the heart/lung rates values of a group of patients diagnosed with IE (2.62+/-0.47) and a group of healthy or control subjects (2.84+/-0.68). However, it is necessary to increase the study sample of both the individuals diagnosed with IE and the control group subjects, as well as to improve the images quality.

  4. Dual-headed SPECT for awake animal brain imaging

    SciTech Connect

    Lee, Seung Joon; Weisenberger, A G; McKisson, J; Goddard Jr, James Samuel; Baba, Justin S; Smith, M F

    2011-01-01

    Abstract- Motion-corrected awake animal imaging is needed for normal-state investigations of models of neurological disease and brain activity. The awake animal brain SPECT/CT system, AwakeSPECT at Johns Hopkins University has in the past used a single gamma camera for imaging. Enhancements have been made by adding a pinhole collimator to the second gamma camera at the opposite side which has been previously equipped parallel hole collimator. Geometry calibration was performed using a custom built quality control phantom containing three Co-57 point sources and applied to the tomographic reconstruction code. Hot-rod phantom scans with Tc-99m were performed to test sensitivity and resolution improvements. The reconstruction results show significant resolution and sensitivity improvements.

  5. Dual-headed SPECT for awake animal brain imaging

    SciTech Connect

    S. Lee, B. Kross, D. Weisenberger, J. McKisson, J.S. Goddard, J.S. Baba, M.S. Smith

    2012-02-01

    Motion-corrected awake animal imaging is needed for normal-state investigations of models of neurological disease and brain activity. The awake animal brain SPECT/CT system, AwakeSPECT at Johns Hopkins University has in the past used a single gamma camera for imaging. Enhancements have been made by adding a pinhole collimator to the second gamma camera at the opposite side which has been previously equipped parallel hole collimator. Geometry calibration was performed using a custom built quality control phantom containing three Co-57 point sources and applied to the tomographic reconstruction code. Hot-rod phantom scans with Tc-99m were performed to test sensitivity and resolution improvements. The reconstruction results show significant resolution and sensitivity improvements.

  6. A novel SPECT camera for molecular imaging of the prostate

    NASA Astrophysics Data System (ADS)

    Cebula, Alan; Gilland, David; Su, Li-Ming; Wagenaar, Douglas; Bahadori, Amir

    2011-10-01

    The objective of this work is to develop an improved SPECT camera for dedicated prostate imaging. Complementing the recent advancements in agents for molecular prostate imaging, this device has the potential to assist in distinguishing benign from aggressive cancers, to improve site-specific localization of cancer, to improve accuracy of needle-guided prostate biopsy of cancer sites, and to aid in focal therapy procedures such as cryotherapy and radiation. Theoretical calculations show that the spatial resolution/detection sensitivity of the proposed SPECT camera can rival or exceed 3D PET and further signal-to-noise advantage is attained with the better energy resolution of the CZT modules. Based on photon transport simulation studies, the system has a reconstructed spatial resolution of 4.8 mm with a sensitivity of 0.0001. Reconstruction of a simulated prostate distribution demonstrates the focal imaging capability of the system.

  7. In Vivo Dosimetry Of Patients Submitted To Brain Spect Studies

    NASA Astrophysics Data System (ADS)

    Cruz-Cortés, D.; Azorín, J.; Saucedo, V. M.

    2004-09-01

    Single photon emission computed tomography (SPECT) is a diagnosis technique which allows to visualize a three dimensional distribution of a radioactive material in the brain. This technique is used for evaluating the blood flux and the metabolic function of the diverse brain regions and is very useful to diagnostic several pathologies such as Alzheimer disease, tumors, epilepsy brain hemorrhages, etc. The radioactive tracer used is 99mTc-labeled hexamethylpropyleneamineoxime (99mTc-HMPAO). We present the results obtained from measurements performed in the chest, back and skull of patients submitted to brain SPECT studies during two hours using home-made LiF:Mg,Cu,P+PTFE thermoluminescent dosimeters. Results obtained showed that the dose received by the patients during two hours are lower than 0.3 mGy.

  8. High-order total variation minimization for interior SPECT

    NASA Astrophysics Data System (ADS)

    Yang, Jiansheng; Yu, Hengyong; Jiang, Ming; Wang, Ge

    2012-01-01

    Recently, we developed an approach for solving the computed tomography (CT) interior problem based on the high-order TV (HOT) minimization, assuming that a region-of-interest (ROI) is piecewise polynomial. In this paper, we generalize this finding from the CT field to the single-photon emission computed tomography (SPECT) field, and prove that if an ROI is piecewise polynomial, then the ROI can be uniquely reconstructed from the SPECT projection data associated with the ROI through the HOT minimization. Also, we propose a new formulation of HOT, which has an explicit formula for any n-order piecewise polynomial function, while the original formulation has no explicit formula for n ⩾ 2. Finally, we verify our theoretical results in numerical simulation, and discuss relevant issues.

  9. Validation of the GEANT4 simulation of bremsstrahlung from thick targets below 3 MeV

    NASA Astrophysics Data System (ADS)

    Pandola, L.; Andenna, C.; Caccia, B.

    2015-05-01

    The bremsstrahlung spectra produced by electrons impinging on thick targets are simulated using the GEANT4 Monte Carlo toolkit. Simulations are validated against experimental data available in literature for a range of energy between 0.5 and 2.8 MeV for Al and Fe targets and for a value of energy of 70 keV for Al, Ag, W and Pb targets. The energy spectra for the different configurations of emission angles, energies and targets are considered. Simulations are performed by using the three alternative sets of electromagnetic models that are available in GEANT4 to describe bremsstrahlung. At higher energies (0.5-2.8 MeV) of the impinging electrons on Al and Fe targets, GEANT4 is able to reproduce the spectral shapes and the integral photon emission in the forward direction. The agreement is within 10-30%, depending on energy, emission angle and target material. The physics model based on the Penelope Monte Carlo code is in slightly better agreement with the measured data than the other two. However, all models over-estimate the photon emission in the backward hemisphere. For the lower energy study (70 keV), which includes higher-Z targets, all models systematically under-estimate the total photon yield, providing agreement between 10% and 50%. The results of this work are of potential interest for medical physics applications, where knowledge of the energy spectra and angular distributions of photons is needed for accurate dose calculations with Monte Carlo and other fluence-based methods.

  10. Bremsstrahlung production at 50 MeV in different target materials and configurations.

    PubMed

    Sätherberg, A; Andreo, P; Karlsson, M

    1996-04-01

    A combination of Monte Carlo, convolution, and experimental techniques have been used to investigate bremsstrahlung production at 50 MeV in full-range targets to produce narrow elementary photon beams for scanning. Calculations using the ITS 3.0 Monte Carlo system for various target designs, including particle transport through the treatment head of an MM5O racetrack microtron and a water phantom, have been compared to experimental dose profiles from narrow photon beams at 10-cm depth in water. A reduction in the ITS 3.0 default substep size has been found necessary even for incomplete agreement, in consistency with the findings of Faddegon and Rogers [Nucl. Instrum. Meth. A 327, 556-565 (1993)] for a different experimental setup and energy using the previous version of ITS. Results show that the calculated shape of the tail of dose distributions from narrow photon beams agrees well with measurements, but CYLTRAN/ITS 3.0 fails to reproduce the central part of the distribution. The discrepancy at small angles, reported previously for EGS4 and ITS 2.1 simulations, possess a limitation to Monte Carlo simulations of narrow photon beams used in scanned systems of clinical accelerators. Radial dose profiles have been calculated by convolution of the energy fluence at the exit of the target with one polyenergetic Monte Carlo calculated dose kernel and also a database consisting of ten different dose kernels corresponding to different monoenergetic photon pencil beams for comparison. The agreement with the much slower fully detailed Monte Carlo calculations was better when using the database kernels than the polyenergetic kernel. Results for the mean energy, mean polar angle, and energy fluence at different depths within various targets have been obtained. These are discussed in the context of the design characteristics of bremsstrahlung targets with emphasis on their utilization for scanning photon beam techniques.

  11. Fermi LAT search for internal bremsstrahlung signatures from dark matter annihilation

    NASA Astrophysics Data System (ADS)

    Bringmann, Torsten; Huang, Xiaoyuan; Ibarra, Alejandro; Vogl, Stefan; Weniger, Christoph

    2012-07-01

    A commonly encountered obstacle in indirect searches for galactic dark matter is how to disentangle possible signals from astrophysical backgrounds. Given that such signals are most likely subdominant, the search for pronounced spectral features plays a key role for indirect detection experiments; monochromatic gamma-ray lines or similar features related to internal bremsstrahlung, in particular, provide smoking gun signatures. We perform a dedicated search for the latter in the data taken by the Fermi gamma-ray space telescope during its first 43 months. To this end, we use a new adaptive procedure to select optimal target regions that takes into account both standard and contracted dark matter profiles. The behaviour of our statistical method is tested by a subsampling analysis of the full sky data and found to reproduce the theoretical expectations very well. The limits on the dark matter annihilation cross-section that we derive are stronger than what can be obtained from the observation of dwarf galaxies and, at least for the model considered here, collider searches. While these limits are still not quite strong enough to probe annihilation rates expected for thermally produced dark matter, future prospects to do so are very good. In fact, we already find a weak indication, with a significance of 3.1σ (4.3σ) when (not) taking into account the look-elsewhere effect, for an internal bremsstrahlung-like signal that would correspond to a dark matter mass of ~150 GeV; the same signal is also well fitted by a gamma-ray line at around 130 GeV. Although this would be a fascinating possibility, we caution that a much more dedicated analysis and additional data will be necessary to rule out or confirm this option.

  12. Bremsstrahlung in Mo and Pt targets produced by {sup 90}Sr beta particles in the photon energy region of 1-100 keV

    SciTech Connect

    Singh, Amrit; Dhaliwal, A. S.

    2015-08-28

    Bremsstrahlung spectra in thick targets of Mo and Pt, produced by beta emitter {sup 90}Sr (end point energy = 546 keV) have been studied in the photon energy range of 1-100 keV. The experimentally measured bremsstrahlung spectra measured with Si(Li) detector were compared with the theoretical spectral distributions calculated from Elwert corrected (non relativistic) Bethe-Heitler [EBH] theory, modified Elwert factor (relativistic) Bethe-Heitler (F{sub mod}BH) theory for ordinary bremsstrahlung (OB) and the modified Elwert factor (relativistic) Bethe-Heitler (F{sub mod}BH+PB) theory, which includes the polarization bremsstrahlung (PB) into total bremsstrahlung (BS). The present results indicate the correctness of F{sub mod}BH+PB theory in the low energy region, where the contributions of PB into BS are dominant, which is described in terms of stripped atom (SA) approximation. But at the middle and higher energy region of the bremsstrahlung spectrum, where the contribution of PB is negligible, the F{sub mod}BH theory is more close to the experimental results. Hence, it is clear that the production of PB in the low energy region, due to the dynamic response of the target atom suppresses the production of bremsstrahlung at higher energy ends.

  13. SVD-based evaluation of multiplexing in multipinhole SPECT systems.

    PubMed

    Jorgensen, Aaron K; Zeng, Gengsheng L

    2008-01-01

    Multipinhole SPECT system design is largely a trial-and-error process. General principles can give system designers a general idea of how a system with certain characteristics will perform. However, the specific performance of any particular system is unknown before the system is tested. The development of an objective evaluation method that is not based on experimentation would facilitate the optimization of multipinhole systems. We derive a figure of merit for prediction of SPECT system performance based on the entire singular value spectrum of the system. This figure of merit contains significantly more information than the condition number of the system, and is therefore more revealing of system performance. This figure is then compared with simulated results of several SPECT systems and is shown to correlate well to the results of the simulations. The proposed figure of merit is useful for predicting system performance, but additional steps could be taken to improve its accuracy and applicability. The limits of the proposed method are discussed, and possible improvements to it are proposed.

  14. Physiological imaging with PET and SPECT in Dementia

    SciTech Connect

    Jagust, W.J. . Dept. of Neurology Lawrence Berkeley Lab., CA )

    1989-10-01

    Dementia is a medical problem of increasingly obvious importance. The most common cause of dementia, Alzheimer's disease (AD) accounts for at least 50% of all cases of dementia, with multi-infarct dementia the next most common cause of the syndrome. While the accuracy of diagnosis of AD may range from 80 to 90%, there is currently no laboratory test to confirm the diagnosis. Functional imaging techniques such as positron emission tomography (PET) and single photon emission computed tomography (SPECT) offer diagnostic advantages since brain function is unequivocally disturbed in all dementing illnesses. Both PET and SPECT have been utilized in the study of dementia. While both techniques rely on principles of emission tomography to produce three dimensional maps of injected radiotracers, the differences between positron and single photon emission have important consequences for the practical applications of the two procedures. This briefly reviews the technical differences between PET and SPECT, and discusses how both techniques have been used in our laboratory to elucidate the pathophysiology of dementia. 32 refs., 2 figs.

  15. Anatomy guided automated SPECT renal seed point estimation

    NASA Astrophysics Data System (ADS)

    Dwivedi, Shekhar; Kumar, Sailendra

    2010-04-01

    Quantification of SPECT(Single Photon Emission Computed Tomography) images can be more accurate if correct segmentation of region of interest (ROI) is achieved. Segmenting ROI from SPECT images is challenging due to poor image resolution. SPECT is utilized to study the kidney function, though the challenge involved is to accurately locate the kidneys and bladder for analysis. This paper presents an automated method for generating seed point location of both kidneys using anatomical location of kidneys and bladder. The motivation for this work is based on the premise that the anatomical location of the bladder relative to the kidneys will not differ much. A model is generated based on manual segmentation of the bladder and both the kidneys on 10 patient datasets (including sum and max images). Centroid is estimated for manually segmented bladder and kidneys. Relatively easier bladder segmentation is followed by feeding bladder centroid coordinates into the model to generate seed point for kidneys. Percentage error observed in centroid coordinates of organs from ground truth to estimated values from our approach are acceptable. Percentage error of approximately 1%, 6% and 2% is observed in X coordinates and approximately 2%, 5% and 8% is observed in Y coordinates of bladder, left kidney and right kidney respectively. Using a regression model and the location of the bladder, the ROI generation for kidneys is facilitated. The model based seed point estimation will enhance the robustness of kidney ROI estimation for noisy cases.

  16. Comparison of heterogeneity quantification algorithms for brain SPECT perfusion images

    PubMed Central

    2012-01-01

    Background Several algorithms from the literature were compared with the original random walk (RW) algorithm for brain perfusion heterogeneity quantification purposes. Algorithms are compared on a set of 210 brain single photon emission computed tomography (SPECT) simulations and 40 patient exams. Methods Five algorithms were tested on numerical phantoms. The numerical anthropomorphic Zubal head phantom was used to generate 42 (6 × 7) different brain SPECT simulations. Seven diffuse cortical heterogeneity levels were simulated with an adjustable Gaussian noise function and six focal perfusion defect levels with temporoparietal (TP) defects. The phantoms were successively projected and smoothed with Gaussian kernel with full width at half maximum (FWHM = 5 mm), and Poisson noise was added to the 64 projections. For each simulation, 5 Poisson noise realizations were performed yielding a total of 210 datasets. The SPECT images were reconstructed using filtered black projection (Hamming filter: α = 0.5). The five algorithms or measures tested were the following: the coefficient of variation, the entropy and local entropy, fractal dimension (FD) (box counting and Fourier power spectrum methods), the gray-level co-occurrence matrix (GLCM), and the new RW. The heterogeneity discrimination power was obtained with a linear regression for each algorithm. This regression line is a mean function of the measure of heterogeneity compared to the different diffuse heterogeneity and focal defect levels generated in the phantoms. A greater slope denotes a larger separation between the levels of diffuse heterogeneity. The five algorithms were computed using 40 99mTc-ethyl-cysteinate-dimer (ECD) SPECT images of patients referred for memory impairment. Scans were blindly ranked by two physicians according to the level of heterogeneity, and a consensus was obtained. The rankings obtained by the algorithms were compared with the physicians' consensus ranking. Results The GLCM method

  17. A parallel Monte Carlo code for planar and SPECT imaging: implementation, verification and applications in (131)I SPECT.

    PubMed

    Dewaraja, Yuni K; Ljungberg, Michael; Majumdar, Amitava; Bose, Abhijit; Koral, Kenneth F

    2002-02-01

    This paper reports the implementation of the SIMIND Monte Carlo code on an IBM SP2 distributed memory parallel computer. Basic aspects of running Monte Carlo particle transport calculations on parallel architectures are described. Our parallelization is based on equally partitioning photons among the processors and uses the Message Passing Interface (MPI) library for interprocessor communication and the Scalable Parallel Random Number Generator (SPRNG) to generate uncorrelated random number streams. These parallelization techniques are also applicable to other distributed memory architectures. A linear increase in computing speed with the number of processors is demonstrated for up to 32 processors. This speed-up is especially significant in Single Photon Emission Computed Tomography (SPECT) simulations involving higher energy photon emitters, where explicit modeling of the phantom and collimator is required. For (131)I, the accuracy of the parallel code is demonstrated by comparing simulated and experimental SPECT images from a heart/thorax phantom. Clinically realistic SPECT simulations using the voxel-man phantom are carried out to assess scatter and attenuation correction.

  18. NOTE: Implementation of angular response function modeling in SPECT simulations with GATE

    NASA Astrophysics Data System (ADS)

    Descourt, P.; Carlier, T.; Du, Y.; Song, X.; Buvat, I.; Frey, E. C.; Bardies, M.; Tsui, B. M. W.; Visvikis, D.

    2010-05-01

    Among Monte Carlo simulation codes in medical imaging, the GATE simulation platform is widely used today given its flexibility and accuracy, despite long run times, which in SPECT simulations are mostly spent in tracking photons through the collimators. In this work, a tabulated model of the collimator/detector response was implemented within the GATE framework to significantly reduce the simulation times in SPECT. This implementation uses the angular response function (ARF) model. The performance of the implemented ARF approach has been compared to standard SPECT GATE simulations in terms of the ARF tables' accuracy, overall SPECT system performance and run times. Considering the simulation of the Siemens Symbia T SPECT system using high-energy collimators, differences of less than 1% were measured between the ARF-based and the standard GATE-based simulations, while considering the same noise level in the projections, acceleration factors of up to 180 were obtained when simulating a planar 364 keV source seen with the same SPECT system. The ARF-based and the standard GATE simulation results also agreed very well when considering a four-head SPECT simulation of a realistic Jaszczak phantom filled with iodine-131, with a resulting acceleration factor of 100. In conclusion, the implementation of an ARF-based model of collimator/detector response for SPECT simulations within GATE significantly reduces the simulation run times without compromising accuracy.

  19. GATE simulation of a new design of pinhole SPECT system for small animal brain imaging

    NASA Astrophysics Data System (ADS)

    Uzun Ozsahin, D.; Bläckberg, L.; El Fakhri, G.; Sabet, H.

    2017-01-01

    Small animal SPECT imaging has gained an increased interest over the past decade since it is an excellent tool for developing new drugs and tracers. Therefore, there is a huge effort on the development of cost-effective SPECT detectors with high capabilities. The aim of this study is to simulate the performance characteristics of new designs for a cost effective, stationary SPECT system dedicated to small animal imaging with a focus on mice brain. The conceptual design of this SPECT system platform, Stationary Small Animal SSA-SPECT, is to use many pixelated CsI:TI detector modules with 0.4 mm × 0.4 mm pixels in order to achieve excellent intrinsic detector resolution where each module is backed by a single pinhole collimator with 0.3 mm hole diameter. In this work, we present the simulation results of four variations of the SSA-SPECT platform where the number of detector modules and FOV size is varied while keeping the detector size and collimator hole size constant. Using the NEMA NU-4 protocol, we performed spatial resolution, sensitivity, image quality simulations followed by a Derenzo-like phantom evaluation. The results suggest that all four SSA-SPECT systems can provide better than 0.063% system sensitivity and < 1.5 mm FWHM spatial resolution without resolution recovery or other correction techniques. Specifically, SSA-SPECT-1 showed a system sensitivity of 0.09% in combination with 1.1 mm FWHM spatial resolution.

  20. A comparison of MR-based attenuation correction in PET versus SPECT

    NASA Astrophysics Data System (ADS)

    Marshall, H. R.; Stodilka, R. Z.; Theberge, J.; Sabondjian, E.; Legros, A.; Deans, L.; Sykes, J. M.; Thompson, R. T.; Prato, F. S.

    2011-07-01

    Attenuation correction (AC) is a critical step in the reconstruction of quantitatively accurate positron emission tomography (PET) and single photon emission computed tomography (SPECT) images. Several groups have proposed magnetic resonance (MR)-based AC algorithms for application in hybrid PET/MR systems. However, none of these approaches have been tested on SPECT data. Since SPECT/MR systems are under active development, it is important to ascertain whether MR-based AC algorithms validated for PET can be applied to SPECT. To investigate this issue, two imaging experiments were performed: one with an anthropomorphic chest phantom and one with two groups of canines. Both groups of canines were imaged from neck to abdomen, one with PET/CT and MR (n = 4) and the other with SPECT/CT and MR (n = 4), while the phantom was imaged with all modalities. The quality of the nuclear medicine reconstructions using MR-based attenuation maps was compared between PET and SPECT on global and local scales. In addition, the sensitivity of these reconstructions to variations in the attenuation map was ascertained. On both scales, it was found that the SPECT reconstructions were of higher fidelity than the PET reconstructions. Further, they were less sensitive to changes to the MR-based attenuation map. Thus, MR-based AC algorithms that have been designed for PET/MR can be expected to demonstrate improved performance when used for SPECT/MR.

  1. Implementation of Angular Response Function modeling in SPECT simulations with GATE

    PubMed Central

    Descourt, P; Carlier, T; Du, Y; Song, X; Buvat, I; Frey, E C; Bardies, M; Tsui, B M W; Visvikis, D

    2010-01-01

    Among Monte Carlo simulation codes in medical imaging, the GATE simulation platform is widely used today given its flexibility and accuracy, despite long run times, which in SPECT simulations, is mostly spent in tracking photons through the collimators. In this work, a tabulated model of the collimator/detector response was implemented within the GATE framework to significantly reduce the simulation times in SPECT. This implementation uses the Angular Response Function (ARF) model. The performance of the implemented ARF approach has been compared to standard SPECT GATE simulations in terms of the ARF tables' accuracy, overall SPECT system performance and run times. Considering the simulation of the Siemens Symbia T SPECT system using high-energy collimators, differences of less than 1% were measured between the ARF based and the standard GATE based simulations, while considering the same noise level in the projections, acceleration factors of up to 180 were obtained when simulating a planar 364keV source seen with the same SPECT system. The ARF-based and the standard GATE simulation results also agreed very well when considering a 4-head SPECT simulation of a realistic Jaszczak phantom filled with iodine-131, with a resulting acceleration factor of 100. In conclusion, the implementation of an ARF-based model of collimator/detector response for SPECT simulations within GATE significantly reduces the simulation run times without compromising accuracy. PMID:20393239

  2. Implementation of angular response function modeling in SPECT simulations with GATE.

    PubMed

    Descourt, P; Carlier, T; Du, Y; Song, X; Buvat, I; Frey, E C; Bardies, M; Tsui, B M W; Visvikis, D

    2010-05-07

    Among Monte Carlo simulation codes in medical imaging, the GATE simulation platform is widely used today given its flexibility and accuracy, despite long run times, which in SPECT simulations are mostly spent in tracking photons through the collimators. In this work, a tabulated model of the collimator/detector response was implemented within the GATE framework to significantly reduce the simulation times in SPECT. This implementation uses the angular response function (ARF) model. The performance of the implemented ARF approach has been compared to standard SPECT GATE simulations in terms of the ARF tables' accuracy, overall SPECT system performance and run times. Considering the simulation of the Siemens Symbia T SPECT system using high-energy collimators, differences of less than 1% were measured between the ARF-based and the standard GATE-based simulations, while considering the same noise level in the projections, acceleration factors of up to 180 were obtained when simulating a planar 364 keV source seen with the same SPECT system. The ARF-based and the standard GATE simulation results also agreed very well when considering a four-head SPECT simulation of a realistic Jaszczak phantom filled with iodine-131, with a resulting acceleration factor of 100. In conclusion, the implementation of an ARF-based model of collimator/detector response for SPECT simulations within GATE significantly reduces the simulation run times without compromising accuracy.

  3. SPECT assay of radiolabeled monoclonal antibodies. Final performance report, March 1992--November 1995

    SciTech Connect

    Jaszczak, R.J.

    1995-12-01

    Research is described in the following areas: development and evaluation quantitatively of reconstruction algorithms with improved compensations for attenuation, scatter, and geometric collimator response; evaluation of single photon emission computed tomography (SPECT) quantification of iodine 123 and astatine 211; and the development and evaluation of SPECT pinhole imaging for low and medium energy photons.

  4. Constrictive pericarditis causing a positive TI-201 SPECT stress test for myocardial ischemia

    SciTech Connect

    Matthews, R.J.; Lightfoote, J.; Grusd, R.S. )

    1990-08-01

    A case of constritive pericarditis was demonstrated by a positive thallium SPECT stress test for myocardial ischemia. After pericardiectomy, the repeat thallium stress test was normal. The disappearance of the criteria for a positive test suggests that constrictive pericarditis can cause myocardial ischemia, which can be demonstrated by thallium SPECT stress testing.

  5. Distinction between hemangioma of the liver and hepatocellular carcinoma: value of labeled RBC-SPECT scanning

    SciTech Connect

    Kudo, M.; Ikekubo, K.; Yamamoto, K.; Ibuki, Y.; Hino, M.; Tomita, S.; Komori, H.; Orino, A.; Todo, A.

    1989-05-01

    The role of adding single-photon emission CT (SPECT) to /sup 99m/Tc-labeled RBC imaging of the liver was evaluated by specifically focusing on the differentiation between hepatic hemangioma and hepatocellular carcinoma. Planar RBC imaging followed by blood-pool SPECT scanning was performed in 77 patients with a total of 108 hemangiomas and in 29 patients with a total of 46 hepatocellular carcinomas. All lesions were smaller than 5 cm in diameter. Thirty-six (33%) of 108 hemangiomas were detected by planar delayed RBC imaging, whereas 63 (58%) were detected by the delayed RBC-SPECT scan. The smallest hemangioma shown by delayed RBC-SPECT scanning was 1.4 cm in diameter, compared with 1.7 cm by planar RBC scanning. When confined to nodules larger than 1.4 cm in diameter, 42% of hemangiomas (36/85) were detected by planar delayed RBC imaging, whereas 74% (63/85) were detected by delayed RBC-SPECT. Increase in sensitivity was noted in nodules 2.1-4.0 cm in diameter. No hepatocellular carcinomas were shown by delayed RBC planar or SPECT scans. We concluded that with the addition of SPECT, the sensitivity of delayed RBC scans in the detection of small hemangiomas is considerably improved. Delayed RBC-SPECT scanning can be used to distinguish hemangioma from hepatocellular carcinoma.

  6. SPECT-OPT multimodal imaging enables accurate evaluation of radiotracers for β-cell mass assessments

    PubMed Central

    Eter, Wael A.; Parween, Saba; Joosten, Lieke; Frielink, Cathelijne; Eriksson, Maria; Brom, Maarten; Ahlgren, Ulf; Gotthardt, Martin

    2016-01-01

    Single Photon Emission Computed Tomography (SPECT) has become a promising experimental approach to monitor changes in β-cell mass (BCM) during diabetes progression. SPECT imaging of pancreatic islets is most commonly cross-validated by stereological analysis of histological pancreatic sections after insulin staining. Typically, stereological methods do not accurately determine the total β-cell volume, which is inconvenient when correlating total pancreatic tracer uptake with BCM. Alternative methods are therefore warranted to cross-validate β-cell imaging using radiotracers. In this study, we introduce multimodal SPECT - optical projection tomography (OPT) imaging as an accurate approach to cross-validate radionuclide-based imaging of β-cells. Uptake of a promising radiotracer for β-cell imaging by SPECT, 111In-exendin-3, was measured by ex vivo-SPECT and cross evaluated by 3D quantitative OPT imaging as well as with histology within healthy and alloxan-treated Brown Norway rat pancreata. SPECT signal was in excellent linear correlation with OPT data as compared to histology. While histological determination of islet spatial distribution was challenging, SPECT and OPT revealed similar distribution patterns of 111In-exendin-3 and insulin positive β-cell volumes between different pancreatic lobes, both visually and quantitatively. We propose ex vivo SPECT-OPT multimodal imaging as a highly accurate strategy for validating the performance of β-cell radiotracers. PMID:27080529

  7. SPECT-OPT multimodal imaging enables accurate evaluation of radiotracers for β-cell mass assessments.

    PubMed

    Eter, Wael A; Parween, Saba; Joosten, Lieke; Frielink, Cathelijne; Eriksson, Maria; Brom, Maarten; Ahlgren, Ulf; Gotthardt, Martin

    2016-04-15

    Single Photon Emission Computed Tomography (SPECT) has become a promising experimental approach to monitor changes in β-cell mass (BCM) during diabetes progression. SPECT imaging of pancreatic islets is most commonly cross-validated by stereological analysis of histological pancreatic sections after insulin staining. Typically, stereological methods do not accurately determine the total β-cell volume, which is inconvenient when correlating total pancreatic tracer uptake with BCM. Alternative methods are therefore warranted to cross-validate β-cell imaging using radiotracers. In this study, we introduce multimodal SPECT - optical projection tomography (OPT) imaging as an accurate approach to cross-validate radionuclide-based imaging of β-cells. Uptake of a promising radiotracer for β-cell imaging by SPECT, (111)In-exendin-3, was measured by ex vivo-SPECT and cross evaluated by 3D quantitative OPT imaging as well as with histology within healthy and alloxan-treated Brown Norway rat pancreata. SPECT signal was in excellent linear correlation with OPT data as compared to histology. While histological determination of islet spatial distribution was challenging, SPECT and OPT revealed similar distribution patterns of (111)In-exendin-3 and insulin positive β-cell volumes between different pancreatic lobes, both visually and quantitatively. We propose ex vivo SPECT-OPT multimodal imaging as a highly accurate strategy for validating the performance of β-cell radiotracers.

  8. Differences in 3D dose distributions due to calculation method of voxel S-values and the influence of image blurring in SPECT

    NASA Astrophysics Data System (ADS)

    Pacilio, Massimiliano; Amato, Ernesto; Lanconelli, Nico; Basile, Chiara; Torres, Leonel Alberto; Botta, Francesca; Ferrari, Mahila; Cornejo Diaz, Nestor; Coca Perez, Marco; Fernández, María; Lassmann, Michael; Vergara Gil, Alex; Cremonesi, Marta

    2015-03-01

    This study compares 3D dose distributions obtained with voxel S values (VSVs) for soft tissue, calculated by several methods at their current state-of-the-art, varying the degree of image blurring. The methods were: 1) convolution of Dose Point Kernel (DPK) for water, using a scaling factor method; 2) an analytical model (AM), fitting the deposited energy as a function of the source-target distance; 3) a rescaling method (RSM) based on a set of high-resolution VSVs for each isotope; 4) local energy deposition (LED). VSVs calculated by direct Monte Carlo simulations were assumed as reference. Dose distributions were calculated considering spheroidal clusters with various sizes (251, 1237 and 4139 voxels of 3 mm size), uniformly filled with 131I, 177Lu, 188Re or 90Y. The activity distributions were blurred with Gaussian filters of various widths (6, 8 and 12 mm). Moreover, 3D-dosimetry was performed for 10 treatments with 90Y derivatives. Cumulative Dose Volume Histograms (cDVHs) were compared, studying the differences in D95%, D50% or Dmax (ΔD95%, ΔD50% and ΔDmax) and dose profiles. For unblurred spheroidal clusters, ΔD95%, ΔD50% and ΔDmax were mostly within some percents, slightly higher for 177Lu with DPK (8%) and RSM (12%) and considerably higher for LED (ΔD95% up to 59%). Increasing the blurring, differences decreased and also LED yielded very similar results, but D95% and D50% underestimations between 30-60% and 15-50%, respectively (with respect to 3D-dosimetry with unblurred distributions), were evidenced. Also for clinical images (affected by blurring as well), cDVHs differences for most methods were within few percents, except for slightly higher differences with LED, and almost systematic for dose profiles with DPK (-1.2%), AM (-3.0%) and RSM (4.5%), whereas showed an oscillating trend with LED. The major concern for 3D-dosimetry on clinical SPECT images is more strongly represented by image blurring than by differences among the VSVs

  9. Differences in 3D dose distributions due to calculation method of voxel S-values and the influence of image blurring in SPECT.

    PubMed

    Pacilio, Massimiliano; Amato, Ernesto; Lanconelli, Nico; Basile, Chiara; Torres, Leonel Alberto; Botta, Francesca; Ferrari, Mahila; Diaz, Nestor Cornejo; Perez, Marco Coca; Fernández, María; Lassmann, Michael; Gil, Alex Vergara; Cremonesi, Marta

    2015-03-07

    This study compares 3D dose distributions obtained with voxel S values (VSVs) for soft tissue, calculated by several methods at their current state-of-the-art, varying the degree of image blurring. The methods were: 1) convolution of Dose Point Kernel (DPK) for water, using a scaling factor method; 2) an analytical model (AM), fitting the deposited energy as a function of the source-target distance; 3) a rescaling method (RSM) based on a set of high-resolution VSVs for each isotope; 4) local energy deposition (LED). VSVs calculated by direct Monte Carlo simulations were assumed as reference. Dose distributions were calculated considering spheroidal clusters with various sizes (251, 1237 and 4139 voxels of 3 mm size), uniformly filled with (131)I, (177)Lu, (188)Re or (90)Y. The activity distributions were blurred with Gaussian filters of various widths (6, 8 and 12 mm). Moreover, 3D-dosimetry was performed for 10 treatments with (90)Y derivatives. Cumulative Dose Volume Histograms (cDVHs) were compared, studying the differences in D95%, D50% or Dmax (ΔD95%, ΔD50% and ΔDmax) and dose profiles.For unblurred spheroidal clusters, ΔD95%, ΔD50% and ΔDmax were mostly within some percents, slightly higher for (177)Lu with DPK (8%) and RSM (12%) and considerably higher for LED (ΔD95% up to 59%). Increasing the blurring, differences decreased and also LED yielded very similar results, but D95% and D50% underestimations between 30-60% and 15-50%, respectively (with respect to 3D-dosimetry with unblurred distributions), were evidenced. Also for clinical images (affected by blurring as well), cDVHs differences for most methods were within few percents, except for slightly higher differences with LED, and almost systematic for dose profiles with DPK (-1.2%), AM (-3.0%) and RSM (4.5%), whereas showed an oscillating trend with LED.The major concern for 3D-dosimetry on clinical SPECT images is more strongly represented by image blurring than by differences among the VSVs

  10. Evaluation of quantitative accuracy in CZT-based pre-clinical SPECT for various isotopes

    NASA Astrophysics Data System (ADS)

    Park, S.-J.; Yu, A. R.; Kim, Y.-s.; Kang, W.-S.; Jin, S. S.; Kim, J.-S.; Son, T. J.; Kim, H.-J.

    2015-05-01

    In vivo pre-clinical single-photon emission computed tomography (SPECT) is a valuable tool for functional small animal imaging, but several physical factors, such as scatter radiation, limit the quantitative accuracy of conventional scintillation crystal-based SPECT. Semiconductor detectors such as CZT overcome these deficiencies through superior energy resolution. To our knowledge, little scientific information exists regarding the accuracy of quantitative analysis in CZT-based pre-clinical SPECT systems for different isotopes. The aim of this study was to assess the quantitative accuracy of CZT-based pre-clinical SPECT for four isotopes: 201Tl, 99mTc, 123I, and 111In. The quantitative accuracy of the CZT-based Triumph X-SPECT (Gamma-Medica Ideas, Northridge, CA, U.S.A.) was compared with that of a conventional SPECT using GATE simulation. Quantitative errors due to the attenuation and scatter effects were evaluated for all four isotopes with energy windows of 5%, 10%, and 20%. A spherical source containing the isotope was placed at the center of the air-or-water-filled mouse-sized cylinder phantom. The CZT-based pre-clinical SPECT was more accurate than the conventional SPECT. For example, in the conventional SPECT with an energy window of 10%, scatter effects degraded quantitative accuracy by up to 11.52%, 5.10%, 2.88%, and 1.84% for 201Tl, 99mTc, 123I, and 111In, respectively. However, with the CZT-based pre-clinical SPECT, the degradations were only 9.67%, 5.45%, 2.36%, and 1.24% for 201Tl, 99mTc, 123I, and 111In, respectively. As the energy window was increased, the quantitative errors increased in both SPECT systems. Additionally, the isotopes with lower energy of photon emissions had greater quantitative error. Our results demonstrated that the CZT-based pre-clinical SPECT had lower overall quantitative errors due to reduced scatter and high detection efficiency. Furthermore, the results of this systematic assessment quantifying the accuracy of these SPECT

  11. A Vector Uniform Cramer-Rao Bound for SPECT System Design

    PubMed Central

    Meng, Ling-Jian; Li, Nan

    2016-01-01

    In this paper, we present the use of modified uniform Cramer-Rao type bounds (MUCRB) for the design of single photon emission tomography (SPECT) systems. The MUCRB is the lowest attainable total variance using any estimator of an unknown vector parameter, whose mean gradient matrix satisfies a given constraint. Since the mean gradient is closely related to local impulse function, the MUCRB approach can be used to evaluate the fundamental tradeoffs between spatial resolution and variance that are achievable with a given SPECT system design. As a possible application, this approach allows one to compare different SPECT system designs based on the optimum average resolution-variance tradeoffs that can be achieved across multiple control-points inside a region-of-interest. The formulation of the MUCRB allows detailed modelling of physical aspects of practical SPECT systems and requests only a modest computation load. It can be used as an analytical performance index for comparing different SPECT system or aperture designs.

  12. Benchmarking of Monte Carlo simulation of bremsstrahlung from thick targets at radiotherapy energies

    PubMed Central

    Faddegon, Bruce A.; Asai, Makoto; Perl, Joseph; Ross, Carl; Sempau, Josep; Tinslay, Jane; Salvat, Francesc

    2008-01-01

    Several Monte Carlo systems were benchmarked against published measurements of bremsstrahlung yield from thick targets for 10–30 MV beams. The quantity measured was photon fluence at 1 m per unit energy per incident electron (spectra), and total photon fluence, integrated over energy, per incident electron (photon yield). Results were reported at 10–30 MV on the beam axis for Al and Pb targets and at 15 MV at angles out to 90° for Be, Al, and Pb targets. Beam energy was revised with improved accuracy of 0.5% using an improved energy calibration of the accelerator. Recently released versions of the Monte Carlo systems EGSNRC, GEANT4, and PENELOPE were benchmarked against the published measurements using the revised beam energies. Monte Carlo simulation was capable of calculation of photon yield in the experimental geometry to 5% out to 30°, 10% at wider angles, and photon spectra to 10% at intermediate photon energies, 15% at lower energies. Accuracy of measured photon yield from 0 to 30° was 5%, 1 s.d., increasing to 7% for the larger angles. EGSNRC and PENELOPE results were within 2 s.d. of the measured photon yield at all beam energies and angles, GEANT4 within 3 s.d. Photon yield at nonzero angles for angles covering conventional field sizes used in radiotherapy (out to 10°), measured with an accuracy of 3%, was calculated within 1 s.d. of measurement for EGSNRC, 2 s.d. for PENELOPE and GEANT4. Calculated spectra closely matched measurement at photon energies over 5 MeV. Photon spectra near 5 MeV were underestimated by as much as 10% by all three codes. The photon spectra below 2–3 MeV for the Be and Al targets and small angles were overestimated by up to 15% when using EGSNRC and PENELOPE, 20% with GEANT4. EGSNRC results with the NIST option for the bremsstrahlung cross section were preferred over the alternative cross section available in EGSNRC and over EGS4. GEANT4 results calculated with the “low energy” physics list were more accurate than

  13. Benchmarking of Monte Carlo simulation of bremsstrahlung from thick targets at radiotherapy energies

    SciTech Connect

    Faddegon, Bruce A.; Asai, Makoto; Perl, Joseph; Ross, Carl; Sempau, Josep; Tinslay, Jane; Salvat, Francesc

    2008-10-15

    Several Monte Carlo systems were benchmarked against published measurements of bremsstrahlung yield from thick targets for 10-30 MV beams. The quantity measured was photon fluence at 1 m per unit energy per incident electron (spectra), and total photon fluence, integrated over energy, per incident electron (photon yield). Results were reported at 10-30 MV on the beam axis for Al and Pb targets and at 15 MV at angles out to 90 degree sign for Be, Al, and Pb targets. Beam energy was revised with improved accuracy of 0.5% using an improved energy calibration of the accelerator. Recently released versions of the Monte Carlo systems EGSNRC, GEANT4, and PENELOPE were benchmarked against the published measurements using the revised beam energies. Monte Carlo simulation was capable of calculation of photon yield in the experimental geometry to 5% out to 30 degree sign , 10% at wider angles, and photon spectra to 10% at intermediate photon energies, 15% at lower energies. Accuracy of measured photon yield from 0 to 30 degree sign was 5%, 1 s.d., increasing to 7% for the larger angles. EGSNRC and PENELOPE results were within 2 s.d. of the measured photon yield at all beam energies and angles, GEANT4 within 3 s.d. Photon yield at nonzero angles for angles covering conventional field sizes used in radiotherapy (out to 10 degree sign ), measured with an accuracy of 3%, was calculated within 1 s.d. of measurement for EGSNRC, 2 s.d. for PENELOPE and GEANT4. Calculated spectra closely matched measurement at photon energies over 5 MeV. Photon spectra near 5 MeV were underestimated by as much as 10% by all three codes. The photon spectra below 2-3 MeV for the Be and Al targets and small angles were overestimated by up to 15% when using EGSNRC and PENELOPE, 20% with GEANT4. EGSNRC results with the NIST option for the bremsstrahlung cross section were preferred over the alternative cross section available in EGSNRC and over EGS4. GEANT4 results calculated with the ''low energy

  14. Qualitative comparison of bremsstrahlung X-rays and 800 MeV protons for tomography of urania fuel pellets

    SciTech Connect

    Morris, Christopher L.; Bourke, Mark A.; Byler, Darrin D.; Chen, Ching-Fong; Hogan, Gary E.; Hunter, James F.; Kwiatkowski, Kris K.; Mariam, Fesseha G.; McClellan, Kenneth J.; Merrill, Frank E.; Morley, Deborah J.; Saunders, Alexander

    2013-02-11

    We present an assessment of x-rays and proton tomography as tools for studying the time dependence of the development of damage in fuel rods. Also, we show data taken with existing facilities at Los Alamos National Laboratory that support this assessment. Data on surrogate fuel rods has been taken using the 800 MeV proton radiography (pRad) facility at the Los Alamos Neutron Science Center (LANSCE), and with a 450 keV bremsstrahlung X-ray tomography facility. The proton radiography pRad facility at LANSCE can provide good position resolution (<70 μm has been demonstrate, 20 μm seems feasible with minor changes) for tomography on activated fuel rods. Bremsstrahlung x-rays may be able to provide better than 100 μm resolution but further development of sources, collimation and detectors is necessary for x-rays to deal with the background radiation for tomography of activated fuel rods.

  15. Comparative evaluation of MRS and SPECT in prognostication of patients with mild to moderate head injury.

    PubMed

    Dhandapani, Sivashanmugam; Sharma, Anurag; Sharma, Karamchand; Das, Lakshman

    2014-05-01

    Magnetic resonance spectroscopy (MRS) and single-photon emission computed tomography (SPECT) have only been individually studied in patients with head injury. This study aimed to comparatively assess both in patients with mild to moderate head injury. Patients with a Glasgow Coma Scale (GCS) score of 9-14 who underwent MRS and/or SPECT were evaluated in relation to various clinical factors and neurological outcome at 3months. There were 56 SPECT (Tc99m-ethylcysteinate dimer [ECD]) studies and 41 single voxel proton MRS performed in 53 patients, with 41 patients having both. Of the 41 who underwent MRS, 13 had a lower N-acetyl-aspartate/creatine (NAA/Cr) ratio, 14 had a higher choline (Cho)/Cr ratio, 19 were normal, and nine had bilateral MRS abnormalities. Of the 56 who underwent SPECT, 22 and 19 had severe and moderate hypoperfusion, respectively. Among those in Traumatic Coma Data Bank CT scan category 1 and 2, 50% had MRS abnormalities, whereas 64% had SPECT hypoperfusion, suggesting greater incremental validity of SPECT over MRS. In univariate analyses, GCS, moderate/severe hypoperfusion and bilateral SPECT changes were found to have significant association with unfavorable outcome (odds ratio 13.2, 15.9, and 4.4, and p values <0.01, 0.01, and 0.05, respectively). Patients with lower NAA/Cr ratio in MRS had more unfavorable outcomes, however this was not significant. In multivariate analysis employing binary logistic regression, GCS and severe hypoperfusion on SPECT were noted to have significant association with unfavorable outcome, independent of age, CT scan category, and MRS abnormalities (p values=0.02 and 0.04, respectively). To conclude, ECD-SPECT seems to have greater sensitivity, incremental validity and prognostic value than single voxel proton MRS in select patients with head injury, with only severe hypoperfusion in SPECT significantly associated with unfavorable outcome independent of other confounding factors.

  16. Modeling Relativistic Electron Precipitation Bremsstrahlung X-Ray Intensities at 10-100 km Manned Vehicle Altitudes

    NASA Astrophysics Data System (ADS)

    Habash Krause, L.; Gilchrist, B. E.; Nishikawa, K.; Williams, A.

    2013-12-01

    Relativistic electron precipitation (REP) events occur when beams or bunches of relativistic electrons of magnetospheric origin enter the Earth's atmosphere, typically at auroral latitudes. REP events are associated with a variety of space weather effects, including production of transitional and bremsstrahlung radiation, catalytic depletion of stratospheric ozone, and scintillation of transionospheric radio waves. This study examines the intensities of x-rays produced at airliner, manned balloon, and suborbital Reusable Launch Vehicle (sRLV) altitudes. The monoenergetic beam is modeled in cylindrical symmetry using the paraxial ray equation. Bremsstrahlung photon production is calculated using the traditional Sauter-Elwert cross-section, providing x-ray emission spectra differential in energy and angle. Attenuation is computed for a plane-stratified standard atmosphere, and the loss processes include photoionization, Rayleigh and Compton scattering, electron-positron pair production, and photonuclear interaction. Peak altitudes of electron energy deposition and bremsstrahlung x-ray production were calculated for beams of energies from 1 MeV through 100 MeV. The altitude peak of bremsstrahlung deposition was consistently and significantly lower that that of the electron deposition due to the longer mean free paths of x-rays compared to electrons within the atmosphere. For example, for a nadir-directed monoenergetic 5 MeV beam, the peak deposition altitude was calculated to be 42 km, but the resulting bremmstrahlung deposition peaked at 25 km. This has implications for crew and passenger safety, especially with the growth of the space tourism industry that relies on sRLVs with a nominal apogee of 100 km. A survey of results covering the 1-100 MeV spectrum for the three altitude ranges of interest will be presented.

  17. SU-E-E-08: Applications of the Quantization of Coupled Circuits in Radiation Physics (design of Klystron, Bremsstrahlung, Synchrotron)

    SciTech Connect

    Ulmer, W

    2015-06-15

    Purpose: During the past decade the quantization of coupled/forced electromagnetic circuits with or without Ohm’s resistance has gained the subject of some fundamental studies, since even problems of quantum electrodynamics can be solved in an elegant manner, e.g. the creation of quantized electromagnetic fields. In this communication, we shall use these principles to describe optimization procedures in the design of klystrons, synchrotron irradiation and high energy bremsstrahlung. Methods: The base is the Hamiltonian of an electromagnetic circuit and the extension to coupled circuits, which allow the study of symmetries and perturbed symmetries in a very apparent way (SU2, SU3, SU4). The introduction resistance and forced oscillators for the emission and absorption in such coupled systems provides characteristic resonance conditions, and atomic orbitals can be described by that. The extension to virtual orbitals leads to creation of bremsstrahlung, if the incident electron (velocity v nearly c) is described by a current, which is associated with its inductivitance and the virtual orbital to the charge distribution (capacitance). Coupled systems with forced oscillators can be used to amplify drastically the resonance frequencies to describe klystrons and synchrotron radiation. Results: The cross-section formula for bremsstrahlung given by the propagator method of Feynman can readily be derived. The design of klystrons and synchrotrons inclusive the radiation outcome can be described and optimized by the determination of the mutual magnetic couplings between the oscillators induced by the currents. Conclusions: The presented methods of quantization of circuits inclusive resistance provide rather a straightforward way to understand complex technical processes such as creation of bremsstrahlung or creation of radiation by klystrons and synchrotrons. They can either be used for optimization procedures and, last but not least, for pedagogical purposes with regard to

  18. Comparisons of Exact Results for the Virtual Correction to Bremsstrahlung in Electron-Positron Annihilation at High Energies

    NASA Astrophysics Data System (ADS)

    Yost, S. A.; Glosser, C.; Jadach, S.; Ward, B. F. L.

    2004-10-01

    We have compared the virtual corrections to single hard bremsstrahlung as calculated by S. Jadach, M. Melles, B.F.L. Ward and S.A. Yost to several other expressions. The most recent of these comparisons is to the leptonic tensor calculated by J.H. Kuhn and G. Rodrigo for radiative return. Agreement is found to within 10-5 or better as a fraction of the Born cross section for most of the range of photon energies.

  19. Navigation of a robot-integrated fluorescence laparoscope in preoperative SPECT/CT and intraoperative freehand SPECT imaging data: a phantom study

    NASA Astrophysics Data System (ADS)

    van Oosterom, Matthias Nathanaël; Engelen, Myrthe Adriana; van den Berg, Nynke Sjoerdtje; KleinJan, Gijs Hendrik; van der Poel, Henk Gerrit; Wendler, Thomas; van de Velde, Cornelis Jan Hadde; Navab, Nassir; van Leeuwen, Fijs Willem Bernhard

    2016-08-01

    Robot-assisted laparoscopic surgery is becoming an established technique for prostatectomy and is increasingly being explored for other types of cancer. Linking intraoperative imaging techniques, such as fluorescence guidance, with the three-dimensional insights provided by preoperative imaging remains a challenge. Navigation technologies may provide a solution, especially when directly linked to both the robotic setup and the fluorescence laparoscope. We evaluated the feasibility of such a setup. Preoperative single-photon emission computed tomography/X-ray computed tomography (SPECT/CT) or intraoperative freehand SPECT (fhSPECT) scans were used to navigate an optically tracked robot-integrated fluorescence laparoscope via an augmented reality overlay in the laparoscopic video feed. The navigation accuracy was evaluated in soft tissue phantoms, followed by studies in a human-like torso phantom. Navigation accuracies found for SPECT/CT-based navigation were 2.25 mm (coronal) and 2.08 mm (sagittal). For fhSPECT-based navigation, these were 1.92 mm (coronal) and 2.83 mm (sagittal). All errors remained below the <1-cm detection limit for fluorescence imaging, allowing refinement of the navigation process using fluorescence findings. The phantom experiments performed suggest that SPECT-based navigation of the robot-integrated fluorescence laparoscope is feasible and may aid fluorescence-guided surgery procedures.

  20. Design and performance of a multi-pinhole collimation device for small animal imaging with clinical SPECT and SPECT-CT scanners

    PubMed Central

    DiFilippo, Frank P.

    2008-01-01

    A multi-pinhole collimation device is developed that uses the gamma camera detectors of a clinical SPECT or SPECT-CT scanner to produce high resolution SPECT images. The device consists of a rotating cylindrical collimator having 22 tungsten pinholes with 0.9 mm diameter apertures and an animal bed inside the collimator that moves linearly to provide helical or ordered-subsets axial sampling. CT images also may be acquired on a SPECT-CT scanner for purposes of image co-registration and SPECT attenuation correction. The device is placed on the patient table of the scanner without attaching to the detectors or scanner gantry. The system geometry is calibrated in-place from point source data and is then used during image reconstruction. The SPECT imaging performance of the device is evaluated with test phantom scans. Spatial resolution from reconstructed point source images is measured to be 0.6 mm full width at half maximum or better. Micro-Derenzo phantom images demonstrate the ability to resolve 0.7 mm diameter rod patterns. The axial slabs of a Micro-Defrise phantom are visualized well. Collimator efficiency exceeds 0.05% at the center of the field of view, and images of a uniform phantom show acceptable uniformity and minimal artifact. The overall simplicity and relatively good imaging performance of the device make it an interesting low-cost alternative to dedicated small animal scanners. PMID:18635899

  1. Design and performance of a multi-pinhole collimation device for small animal imaging with clinical SPECT and SPECT CT scanners

    NASA Astrophysics Data System (ADS)

    Di Filippo, Frank P.

    2008-08-01

    A multi-pinhole collimation device is developed that uses the gamma camera detectors of a clinical SPECT or SPECT-CT scanner to produce high-resolution SPECT images. The device consists of a rotating cylindrical collimator having 22 tungsten pinholes with 0.9 mm diameter apertures and an animal bed inside the collimator that moves linearly to provide helical or ordered-subsets axial sampling. CT images also may be acquired on a SPECT-CT scanner for purposes of image co-registration and SPECT attenuation correction. The device is placed on the patient table of the scanner without attaching to the detectors or scanner gantry. The system geometry is calibrated in-place from point source data and is then used during image reconstruction. The SPECT imaging performance of the device is evaluated with test phantom scans. Spatial resolution from reconstructed point source images is measured to be 0.6 mm full width at half maximum or better. Micro-Derenzo phantom images demonstrate the ability to resolve 0.7 mm diameter rod patterns. The axial slabs of a Micro-Defrise phantom are visualized well. Collimator efficiency exceeds 0.05% at the center of the field of view, and images of a uniform phantom show acceptable uniformity and minimal artifact. The overall simplicity and relatively good imaging performance of the device make it an interesting low-cost alternative to dedicated small animal scanners.

  2. The small contribution of molecular Bremsstrahlung radiation to the air-fluorescence yield of cosmic ray shower particles

    NASA Astrophysics Data System (ADS)

    Al Samarai, Imen; Deligny, Olivier; Rosado, Jaime

    2016-10-01

    A small contribution of molecular Bremsstrahlung radiation to the air-fluorescence yield in the UV range is estimated based on an approach previously developed in the framework of the radio-detection of showers in the gigahertz frequency range. First, this approach is shown to provide an estimate of the main contribution of the fluorescence yield due to the de-excitation of the C 3Πu electronic level of nitrogen molecules to the B 3Πg one amounting to Y[ 337 ] =(6.05 ± 1.50) MeV-1 at 800 hPa pressure and 293 K temperature conditions, which compares well to previous dedicated works and to experimental results. Then, under the same pressure and temperature conditions, the fluorescence yield induced by molecular Bremsstrahlung radiation is found to be Y[330-400]MBR = 0.10 MeV-1 in the wavelength range of interest for the air-fluorescence detectors used to detect extensive air showers induced in the atmosphere by ultra-high energy cosmic rays. This means that out of ≃175 photons with wavelength between 330 and 400 nm detected by fluorescence detectors, one of them has been produced by molecular Bremsstrahlung radiation. Although small, this contribution is not negligible in regards to the total budget of systematic uncertainties when considering the absolute energy scale of fluorescence detectors.

  3. Determination of the parametric region in which runaway electron energy losses are dominated by bremsstrahlung radiation in tokamaks

    SciTech Connect

    Fernandez-Gomez, I.; Martin-Solis, J. R.; Sanchez, R.

    2007-07-15

    It has been recently argued that, at sufficiently large parallel electric fields, bremsstrahlung radiation can greatly reduce the maximum energy that runaway electrons can gain in tokamaks [M. Bakhtiari et al., Phys. Plasmas 12, 102503 (2005)]. In this contribution, the work of these authors is extended to show that the region where bremsstrahlung radiation dominate runaway energy losses is however more restricted than reported by them. Expressions will be provided for the limits of this region within the parameter space spanned by the background density and parallel electric field, as a function of the rest of the plasma parameters. It will be shown that the background density has to be above a certain critical value and that the parallel electric field must lie within a range of values, below and above which synchrotron radiation dominate the runaway energy losses. Finally, it will be demonstrated that typical disruption parameters lie within this region and, as a result, bremsstrahlung losses still play an important role in controlling the runaway energy.

  4. Impact of subcortical white matter lesions on dopamine transporter SPECT.

    PubMed

    Funke, Elisabeth; Kupsch, Andreas; Buchert, Ralph; Brenner, Winfried; Plotkin, Michail

    2013-07-01

    Subcortical arteriosclerotic encephalopathy (SAE) can affect the nigrostriatal system and presumably cause vascular parkinsonism (VP). However, in patients with SAE, the differentiation of VP from idiopathic Parkinson's disease (IPS) is challenging. The aim of the present study was to examine the striatal dopamine transporter (DAT) density in patients with parkinsonism and SAE. Fifteen consecutive patients with parkinsonian symptoms displayed SAE, as detected by magnetic resonance imaging (MRI). Fifteen retrospectively chosen, matched patients with diagnosis of IPS without any abnormalities in MRI served as a reference group. DAT SPECT was performed using the tracer ¹²³I-FP-CIT. Scans were acquired on a triple-head SPECT system (Multispect 3, Siemens) and analysed using the investigator-independent BRASS™ software (HERMES). In the SAE group, a DAT deficit was observed in 9/15 patients. In contrast, all patients from the IPS group showed a reduced DAT binding (p = 0.008). The specific binding ratios (BR) of putamen contralateral to the side of the more affected limb versus occipital lobe were in trend higher in patients with SAE versus patients in the IPS-group (p = 0.053). Indices for putaminal asymmetry (p = 0.036) and asymmetry caudate-to-putamen (p = 0.026) as well as the ratio caudate-to-putamen (p = 0.048) were significantly higher in IPS patients having no SAE. DAT deficit was less pronounced in patients with SAE and parkinsonism than in patients with IPS without any abnormalities in the MRI. A potential role of DAT SPECT in the differential diagnosis of VP and IPS requires more assessments within prospective studies.

  5. Impact of reconstruction parameters on quantitative I-131 SPECT

    NASA Astrophysics Data System (ADS)

    van Gils, C. A. J.; Beijst, C.; van Rooij, R.; de Jong, H. W. A. M.

    2016-07-01

    Radioiodine therapy using I-131 is widely used for treatment of thyroid disease or neuroendocrine tumors. Monitoring treatment by accurate dosimetry requires quantitative imaging. The high energy photons however render quantitative SPECT reconstruction challenging, potentially requiring accurate correction for scatter and collimator effects. The goal of this work is to assess the effectiveness of various correction methods on these effects using phantom studies. A SPECT/CT acquisition of the NEMA IEC body phantom was performed. Images were reconstructed using the following parameters: (1) without scatter correction, (2) with triple energy window (TEW) scatter correction and (3) with Monte Carlo-based scatter correction. For modelling the collimator-detector response (CDR), both (a) geometric Gaussian CDRs as well as (b) Monte Carlo simulated CDRs were compared. Quantitative accuracy, contrast to noise ratios and recovery coefficients were calculated, as well as the background variability and the residual count error in the lung insert. The Monte Carlo scatter corrected reconstruction method was shown to be intrinsically quantitative, requiring no experimentally acquired calibration factor. It resulted in a more accurate quantification of the background compartment activity density compared with TEW or no scatter correction. The quantification error relative to a dose calibrator derived measurement was found to be  <1%,-26% and 33%, respectively. The adverse effects of partial volume were significantly smaller with the Monte Carlo simulated CDR correction compared with geometric Gaussian or no CDR modelling. Scatter correction showed a small effect on quantification of small volumes. When using a weighting factor, TEW correction was comparable to Monte Carlo reconstruction in all measured parameters, although this approach is clinically impractical since this factor may be patient dependent. Monte Carlo based scatter correction including accurately simulated CDR

  6. Multipinhole collimator with 20 apertures for a brain SPECT application

    SciTech Connect

    Lee, Tzu-Cheng; Ellin, Justin R.; Shrestha, Uttam; Seo, Youngho; Huang, Qiu; Gullberg, Grant T.

    2014-11-01

    Purpose: Several new technologies for single photon emission computed tomography (SPECT) instrumentation with parallel-hole collimation have been proposed to improve detector sensitivity and signal collection efficiency. Benefits from improved signal efficiency include shorter acquisition times and lower dose requirements. In this paper, the authors show a possibility of over an order of magnitude enhancement in photon detection efficiency (from 7.6 × 10{sup −5} to 1.6 × 10{sup −3}) for dopamine transporter (DaT) imaging of the striatum over the conventional SPECT parallel-hole collimators by use of custom-designed 20 multipinhole (20-MPH) collimators with apertures of 0.75 cm diameter. Methods: Quantifying specific binding ratio (SBR) of {sup 123}I-ioflupane or {sup 123}I-iometopane’s signal at the striatal region is a common brain imaging method to confirm the diagnosis of the Parkinson’s disease. The authors performed imaging of a striatal phantom filled with aqueous solution of I-123 and compared camera recovery ratios of SBR acquired between low-energy high-resolution (LEHR) parallel-hole collimators and 20-MPH collimators. Results: With only two-thirds of total acquisition time (20 min against 30 min), a comparable camera recovery ratio of SBR was achieved using 20-MPH collimators in comparison to that from the LEHR collimator study. Conclusions: Their systematic analyses showed that the 20-MPH collimator could be a promising alternative for the DaT SPECT imaging for brain over the traditional LEHR collimator, which could give both shorter scan time and improved diagnostic accuracy.

  7. High Sensitivity SPECT for Small Animals and Plants

    SciTech Connect

    Mitchell, Gregory S.

    2015-02-28

    Imaging systems using single gamma-ray emitting radioisotopes typically implement collimators in order to form the images. However, a tradeoff in sensitivity is inherent in the use of collimators, and modern preclinical single-photon emission computed tomography (SPECT) systems detect a very small fraction of emitted gamma-rays (<0.3%). We have built a collimator-less system, which can reach sensitivity of 40% for 99mTc imaging, while still producing images of sufficient spatial resolution for certain applications in thin objects such as mice, small plants, and well plates used for in vitro experiments.

  8. Bremsstrahlung-Based Imaging and Assays of Radioactive, Mixed and Hazardous Waste

    NASA Astrophysics Data System (ADS)

    Kwofie, J.; Wells, D. P.; Selim, F. A.; Harmon, F.; Duttagupta, S. P.; Jones, J. L.; White, T.; Roney, T.

    2003-08-01

    A new nondestructive accelerator based x-ray fluorescence (AXRF) approach has been developed to identify heavy metals in large-volume samples. Such samples are an important part of the process and waste streams of U.S Department of Energy sites, as well as other industries such as mining and milling. Distributions of heavy metal impurities in these process and waste samples can range from homogeneous to highly inhomogeneous, and non-destructive assays and imaging that can address both are urgently needed. Our approach is based on using high-energy, pulsed bremsstrahlung beams (3-6.5 MeV) from small electron accelerators to produce K-shell atomic fluorescence x-rays. In addition we exploit pair-production, Compton scattering and x-ray transmission measurements from these beams to probe locations of high density and high atomic number. The excellent penetrability of these beams allows assays and images for soil-like samples at least 15 g/cm2 thick, with elemental impurities of atomic number greater than approximately 50. Fluorescence yield of a variety of targets was measured as a function of impurity atomic number, impurity homogeneity, and sample thickness. We report on actual and potential detection limits of heavy metal impurities in a soil matrix for a variety of samples, and on the potential for imaging, using AXRF and these related probes.

  9. The bremsstrahlung tagged photon beam in Hall B at the Jefferson Laboratory

    SciTech Connect

    Daniel I. Sober; Hall Crannell; Alberto Longhi; Scott Matthews; James T. O'Brien; Barry L. Berman; William Briscoe; Philip L. Cole; James Connelly; W.R. Dodge; Luc Y. Murphy; S.A. Phillips; Michael Dugger; David Lawrence; Barry G. Ritchie; Elton Smith; J.M. Lambert; Eric P.M. Anciant; Gerad Audit; Thierry Auger; Claude Marchand; Michael Klusman; James Napolitano; M.A. Khandaker; Carlos Salgado; Adam Sarty

    2000-02-01

    We describe the design and commissioning of the photon tagging beamline installed in experimental Hall B at the Thomas Jefferson National Accelerator Facility (Jlab). This system can tag photon energies over a range from 20% to 95% of the incident electron energy, and is capable of operation with beam energies up to 6.1 GeV. A single dipole magnet is combined with a hodoscope containing two planar arrays of plastic scintillators to detect energy-degraded electrons from a thin bremsstrahlung radiator. The first layer of 384 partially overlapping small scintillators provides photon energy resolution, while the second layer of 61 larger scintillators provides the timing resolution necessary to form a coincidence with the corresponding nuclear interaction triggered by the tagged photon. The definitions of overlap channels in the first counter plane and of geometric correlation between the two planes are determined using digitized time information from the individual counters. Auxiliary beamline devices are briefly described, and performance results to date under real operating conditions are presented. The entire photon-tagging system has met or exceeded its design goals.

  10. Bremsstrahlung and gamma ray lines in 3 scenarios of dark matter annihilation

    SciTech Connect

    Giacchino, Federica; Tytgat, Michel H.G.; Lopez-Honorez, Laura E-mail: llopezho@vub.ac.be

    2014-08-01

    Gamma ray spectral features are of interest for indirect searches of dark matter (DM). Following Barger et al. we consider 3 simple scenarios of DM that annihilates into Standard Model (SM) fermion pairs. Scenario 1 is a Majorana DM candidate coupled to a charged scalar, scenario 2 is a Majorana DM coupled to a charged gauge boson and scenario 3 is a real scalar DM coupled a charged vector-like fermion. As shown by Barger et al., these 3 scenarios share precisely the same internal Bremsstrahlung spectral signature into gamma rays. Their phenomenology is however distinct. In particular for annihilation into light SM fermions, in the chiral limit, the 2-body annihilation cross section is p-wave suppressed for the Majorana candidates while it is d-wave suppressed for the real scalar. In the present work we study the annihilation into 2 gammas, showing that these three scenarios have distinct, and so potentially distinguishable, spectral signatures into gamma rays. In the case of the real scalar candidate we provide a new calculation of the amplitude for annihilation into 2 gammas.

  11. Inverse bremsstrahlung heating beyond the first Born approximation for dense plasmas in laser fields

    NASA Astrophysics Data System (ADS)

    Moll, M.; Schlanges, M.; Bornath, Th; Krainov, V. P.

    2012-06-01

    Inverse bremsstrahlung (IB) heating, an important process in the laser-matter interaction, involves two different kinds of interaction—the interaction of the electrons with the external laser field and the electron-ion interaction. This makes analytical approaches very difficult. In a quantum perturbative approach to the IB heating rate in strong laser fields, usually the first Born approximation with respect to the electron-ion potential is considered, whereas the influence of the electric field is taken exactly in the Volkov wave functions. In this paper, a perturbative treatment is presented adopting a screened electron-ion interaction potential. As a new result, we derive the momentum-dependent, angle-averaged heating rate in the first Born approximation. Numerical results are discussed for a broad range of field strengths, and the conditions for the applicability of a linear approximation for the heating rate are analyzed in detail. Going a step further in the perturbation series, we consider the transition amplitude in the second Born approximation, which enables us to calculate the heating rate up to the third order of the interaction strength.

  12. Hydramite II screening tests of potential bremsstrahlung converter debris shield materials

    SciTech Connect

    Reedy, E.D. Jr.; Hedemann, M.A.; Stark, M.A.

    1986-03-01

    Results of a brief test series aimed at screening a number of potential bremsstrahlung converter debris shield materials are reported. These tests were run on Sandia National Laboratories' Hydramite II accelerator using a diode configuration which produces a pinched electron beam. The materials tested include: (1) laminated Kevlar 49/polyester and E-glass/polyester composites, (2) a low density laminated Kevlar 49 composite, and (3) two types of through-the-thickness reinforced Kevlar 49 composites. As expected, tests using laminated Kevlar 49/polyester shields showed that shield permanent set (i.e., permanent deflection) increased with increasing tantalum conversion foil thickness and decreased with increasing shield thickness. The through-the-thickness reinforced composites developed localized, but severe, back surface damage. The laminated composites displayed little back surface damage, although extensive internal matrix cracking and ply delaminations were generated. Roughly the same degree of permanent set was produced in shields made from the low density Kevlar 49 composite and the Kevlar 49/polyester. The E-glass reinforced shields exhibited relatively low levels of permanent set.

  13. Comparison of two different types of LiF:Mg,Cu,P thermoluminescent dosimeters for detection of beta rays (beta-TLDs) from 90Sr/90Y, 85Kr and 147Pm sources.

    PubMed

    Grassi, Elisa; Sghedoni, Roberto; Piccagli, Vando; Fioroni, Federica; Borasi, Giovanni; Iori, Mauro

    2011-05-01

    Targeted radionuclide therapies in nuclear medicine departments increasingly depend on using unsealed beta radiation sources in the labeling of peptides and antibodies. Monitoring doses received by the fingers and hands during these procedures is best accomplished with TLD dosimeters that can be located at the fingertips. The present study examines the response of two TLD dosimeters (MCP-Ns and GR200A) to 90Sr/90Y, 85Kr, and 147Pm. The dosimeters were supplied by two different services, and all irradiations were performed at the PTB Institute in Germany. Each dosimetry service evaluated the dosimeters without knowledge that they had been purposefully irradiated. The accuracy and precision of the dosimeters were evaluated as a function of delivered dose, energy of beta particles and angular incidence. The results are compared to performance measures recommended by the IEC. Both dosimeter types displayed significant energy dependence. Angular dependence was moderate. Accuracy and precision as a function of dose (linearity) differed between the two systems, with the MCP-Ns being noticeably better than the GR200A. The superior precision makes the MCP-Ns much more useful for extremity dose measurements. The differences between these two dosimeter systems reinforce the need to evaluate a dosimeter carefully before using it in the daily work routine.

  14. Short-course R-CHOP followed by 90Y-Ibritumomab tiuxetan in previously untreated high-risk elderly diffuse large B-cell lymphoma patients: 7-year long-term results

    PubMed Central

    Stefoni, V; Casadei, B; Bottelli, C; Gaidano, G; Ciochetto, C; Cabras, M G; Ansuinelli, M; Argnani, L; Broccoli, A; Gandolfi, L; Pellegrini, C; Zinzani, P L

    2016-01-01

    An update at 7 years was conceived for our multicenter phase II study in which 55 elderly high-risk untreated diffuse large B-cell lymphoma patients were treated with 90Y-ibritumomab tiuxetan after a short course of rituximab, cyclophosphamide, doxorubicin, vincristine and prednisolone (R-CHOP) as long-term follow-up analyses of this combined therapeutic modality are lacking. The overall response rate to the entire regimen was 80%, including 73% (40/55) of complete response (CR) rate and 7% (4/55) of partial response rate. At the time of writing, 24/55 (43.6%) patients experienced a progression disease and 20 of 40 (50%) patients who obtained a CR are still alive in continuous CR. With a median follow-up of 7 years, the disease-free survival was 43.3% and the progression-free survival was 36.1%. The overall survival at 7.9 years was 38.9% (27 deaths mainly because of lymphoma). Two patients developed secondary hematological malignancies, an acute myeloid leukemia and a myelodysplastic syndrome, at 4 and 3 years from radioimmunotherapy, respectively. Our data confirm the feasibility, efficacy and safety of four cycles of R-CHOP followed by radioimmunotherapy consolidation even in the long term: this combination allows dispensing less chemotherapy in a frail group of patients without invalidating response quality and duration. PMID:27176801

  15. Intrinsic Feature Pose Measurement for Awake Animal SPECT Imaging

    SciTech Connect

    Goddard Jr, James Samuel; Baba, Justin S; Lee, Seung Joon; Weisenberger, A G; Stolin, A; McKisson, J; Smith, M F

    2009-01-01

    New developments have been made in optical motion tracking for awake animal imaging that measures 3D position and orientation (pose) for a single photon emission computed tomography (SPECT) imaging system. Ongoing SPECT imaging research has been directed towards head motion measurement for brain studies in awake, unrestrained mice. In contrast to previous results using external markers, this work extracts and tracks intrinsic features from multiple camera images and computes relative pose from the tracked features over time. Motion tracking thus far has been limited to measuring extrinsic features such as retro-reflective markers applied to the mouse s head. While this approach has been proven to be accurate, the additional animal handling required to attach the markers is undesirable. A significant improvement in the procedure is achieved by measuring the pose of the head without extrinsic markers using only the external surface appearance. This approach is currently being developed with initial results presented here. The intrinsic features measurement extracts discrete, sparse natural features from 2D images such as eyes, nose, mouth and other visible structures. Stereo correspondence between features for a camera pair is determined for calculation of 3D positions. These features are also tracked over time to provide continuity for surface model fitting. Experimental results from live images are presented.

  16. Optimizing multi-pinhole SPECT geometries using an analytical model

    NASA Astrophysics Data System (ADS)

    Rentmeester, M. C. M.; van der Have, F.; Beekman, F. J.

    2007-05-01

    State-of-the-art multi-pinhole SPECT devices allow for sub-mm resolution imaging of radio-molecule distributions in small laboratory animals. The optimization of multi-pinhole and detector geometries using simulations based on ray-tracing or Monte Carlo algorithms is time-consuming, particularly because many system parameters need to be varied. As an efficient alternative we develop a continuous analytical model of a pinhole SPECT system with a stationary detector set-up, which we apply to focused imaging of a mouse. The model assumes that the multi-pinhole collimator and the detector both have the shape of a spherical layer, and uses analytical expressions for effective pinhole diameters, sensitivity and spatial resolution. For fixed fields-of-view, a pinhole-diameter adapting feedback loop allows for the comparison of the system resolution of different systems at equal system sensitivity, and vice versa. The model predicts that (i) for optimal resolution or sensitivity the collimator layer with pinholes should be placed as closely as possible around the animal given a fixed detector layer, (ii) with high-resolution detectors a resolution improvement up to 31% can be achieved compared to optimized systems, (iii) high-resolution detectors can be placed close to the collimator without significant resolution losses, (iv) interestingly, systems with a physical pinhole diameter of 0 mm can have an excellent resolution when high-resolution detectors are used.

  17. SPECT in Alzheimer`s disease and the dementias

    SciTech Connect

    Bonte, F.J.

    1991-12-31

    Among 90 patients with a clinical diagnosis of Alzheimer`s disease (AD), two subgroups were identified for special study, including 42 patients who had a history of dementia in one or more first-degree relatives, and 14 who had a diagnosis of early AD. Of the 42 patients with a family history of dementia, 34 out of the 35 patients whose final clinical diagnosis was possible or probable AD had positive SPECT rCBF studies. Studies in the 14 patients thought to have very early AD were positive in 11 cases. This finding suggests that altered cortical physiology, and hence, rCBF, occurs quite early in the course of AD, perhaps before the onset of symptoms. It is possible that Xenon 133 rCBF studies might be used to detect the presence of subclinical AD in a population of individuals at risk to this disorder. Despite the drawbacks of a radionuclide with poor photon energy, Xenon 133, with its low cost and round-the-clock availability, deserves further study. Although the physical characteristics of Xenon 127 might make it preferable as a SPECT tracer, it is still not regularly available, and some instrument systems are not designed to handle its higher photon energies.

  18. Development of PET and SPECT Probes for Glutamate Receptors

    PubMed Central

    Nakayama, Morio

    2015-01-01

    l-Glutamate and its receptors (GluRs) play a key role in excitatory neurotransmission within the mammalian central nervous system (CNS). Impaired regulation of GluRs has also been implicated in various neurological disorders. GluRs are classified into two major groups: ionotropic GluRs (iGluRs), which are ligand-gated ion channels, and metabotropic GluRs (mGluRs), which are coupled to heterotrimeric guanosine nucleotide binding proteins (G-proteins). Positron emission tomography (PET) and single photon emission computed tomography (SPECT) imaging of GluRs could provide a novel view of CNS function and of a range of brain disorders, potentially leading to the development of new drug therapies. Although no satisfactory imaging agents have yet been developed for iGluRs, several PET ligands for mGluRs have been successfully employed in clinical studies. This paper reviews current progress towards the development of PET and SPECT probes for GluRs. PMID:25874256

  19. Brain SPECT findings of anosognosia in Alzheimer's disease.

    PubMed

    Sedaghat, Fereshteh; Dedousi, Eleni; Baloyannis, Ioannis; Tegos, Thomas; Costa, Vasiliki; Dimitriadis, Athanasios S; Baloyannis, Stavros J

    2010-01-01

    Anosognosia is a common symptom of dementia. The aim of this study was to evaluate the contribution of different regions of the brain to anosognosia in Alzheimer's disease (AD) brains using single photon emission computed tomography (SPECT). Forty-two patients with AD were included in this study. After clinical interviews with the patients and their relatives, the patients were divided into two groups: Anosognosia and No-anosognosia. The patients were studied regarding the severity of dementia. They underwent SPECT with HMPAO and regional cerebral blood flow (rCBF) was measured. Regional CBF significantly differed between Anosognosia and No-anosognosia groups in right prefrontal (P < or = 0.02), right inferior parietal (P < or = 0.00), and right (P < or = 0.01) and left (P < or = 0.01) medial temporal cortex. There was a significant correlation between the severity of dementia and rCBF in medial temporal regions. When comparisons were made between mild and moderate stages separately, the 'right inferior parietal region' was the common region which showed hypoperfusion in both anosognosia subgroups. We conclude that anosognosia may be a reflection of functional impairment in right prefrontal, right frontal and especially right inferior parietal regions in AD.

  20. Adaptive SPECT imaging with crossed-slit apertures

    PubMed Central

    Durko, Heather L.; Furenlid, Lars R.

    2015-01-01

    Preclinical single-photon emission computed tomography (SPECT) is an essential tool for studying the progression, response to treatment, and physiological changes in small animal models of human disease. The wide range of imaging applications is often limited by the static design of many preclinical SPECT systems. We have developed a prototype imaging system that replaces the standard static pinhole aperture with two sets of movable, keel-edged copper-tungsten blades configured as crossed (skewed) slits. These apertures can be positioned independently between the object and detector, producing a continuum of imaging configurations in which the axial and transaxial magnifications are not constrained to be equal. We incorporated a megapixel silicon double-sided strip detector to permit ultrahigh-resolution imaging. We describe the configuration of the adjustable slit aperture imaging system and discuss its application toward adaptive imaging, and reconstruction techniques using an accurate imaging forward model, a novel geometric calibration technique, and a GPU-based ultra-high-resolution reconstruction code. PMID:26190884

  1. New SPECT and PET Radiopharmaceuticals for Imaging Cardiovascular Disease

    PubMed Central

    Sogbein, Oyebola O.; Pelletier-Galarneau, Matthieu; Schindler, Thomas H.; Wei, Lihui; Wells, R. Glenn; Ruddy, Terrence D.

    2014-01-01

    Nuclear cardiology has experienced exponential growth within the past four decades with converging capacity to diagnose and influence management of a variety of cardiovascular diseases. Single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) with technetium-99m radiotracers or thallium-201 has dominated the field; however new hardware and software designs that optimize image quality with reduced radiation exposure are fuelling a resurgence of interest at the preclinical and clinical levels to expand beyond MPI. Other imaging modalities including positron emission tomography (PET) and magnetic resonance imaging (MRI) continue to emerge as powerful players with an expanded capacity to diagnose a variety of cardiac conditions. At the forefront of this resurgence is the development of novel target vectors based on an enhanced understanding of the underlying pathophysiological process in the subcellular domain. Molecular imaging with novel radiopharmaceuticals engineered to target a specific subcellular process has the capacity to improve diagnostic accuracy and deliver enhanced prognostic information to alter management. This paper, while not comprehensive, will review the recent advancements in radiotracer development for SPECT and PET MPI, autonomic dysfunction, apoptosis, atherosclerotic plaques, metabolism, and viability. The relevant radiochemistry and preclinical and clinical development in addition to molecular imaging with emerging modalities such as cardiac MRI and PET-MR will be discussed. PMID:24901002

  2. SPECT, MRI and cognitive functions in multiple sclerosis.

    PubMed Central

    Pozzilli, C; Passafiume, D; Bernardi, S; Pantano, P; Incoccia, C; Bastianello, S; Bozzao, L; Lenzi, G L; Fieschi, C

    1991-01-01

    Seventeen patients with relapsing remitting multiple sclerosis (MS) and mild physical disability had neuropsychological testing, magnetic resonance imaging (MRI) and single photon emission computerised tomography (SPECT) using technetium 99m (99mTc) hexamethyl-propyleneamine oxime (HMPAO). Performance in verbal fluency, naming and memory testing appeared to be impaired in MS patients compared with 17 age-sex and education matched normal controls. Weighted periventricular and confluent lesion scores and the width of the third ventricle, proved to be the most sensitive MRI measures in differentiating more cognitively impaired patients from those who were relatively unimpaired. Ratios of regional to whole brain activity, measured by SPECT, showed significant reduction in the frontal lobes and in the left temporal lobe of MS patients. A relationship was found between left temporal abnormality in 99mTc-HMPAO uptake and deficit in verbal fluency and verbal memory. Finally, asymmetrical lobar activity indicated a predominant left rather than right temporo-parietal involvement. PMID:2019835

  3. Radiotracers for PET and SPECT studies of neurotransmitter systems

    SciTech Connect

    Fowler, J.S.

    1991-01-01

    The study of neurotransmitter systems is one of the major thrusts in emission tomography today. The current generation of Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT) radiotracers examines neurotransmitter properties from a number of different perspectives including their pre and post synaptic sites and the activity of the enzymes which regulate their concentration. Although the dopamine system has been the most extensively investigated, other neurotransmitter systems including the acetylcholine muscarine, serotonin, benzodiazepine, opiate, NMDA and others are also under intensive development. Enzymes involved in the synthesis and regulation of neurotransmitter concentration, for example monoamine oxidase and amino acid decarboxylase has also been probed in vivo. Medical applications range from the study of normal function and the characterization of neurotransmitter activity in neurological and psychiatric diseases and in heart disease and cancer to the study of the binding of therapeutic drugs and substances of abuse. This chapter will provide an overview of the current generation of radiotracers for PET and SPECT studies of neurotransmitter systems including radiotracer design, synthesis localization mechanisms and applications in emission tomography. 60 refs., 1 tab.

  4. Simultaneous reconstruction and segmentation for dynamic SPECT imaging

    NASA Astrophysics Data System (ADS)

    Burger, Martin; Rossmanith, Carolin; Zhang, Xiaoqun

    2016-10-01

    This work deals with the reconstruction of dynamic images that incorporate characteristic dynamics in certain subregions, as arising for the kinetics of many tracers in emission tomography (SPECT, PET). We make use of a basis function approach for the unknown tracer concentration by assuming that the region of interest can be divided into subregions with spatially constant concentration curves. Applying a regularised variational framework reminiscent of the Chan-Vese model for image segmentation we simultaneously reconstruct both the labelling functions of the subregions as well as the subconcentrations within each region. Our particular focus is on applications in SPECT with the Poisson noise model, resulting in a Kullback-Leibler data fidelity in the variational approach. We present a detailed analysis of the proposed variational model and prove existence of minimisers as well as error estimates. The latter apply to a more general class of problems and generalise existing results in literature since we deal with a nonlinear forward operator and a nonquadratic data fidelity. A computational algorithm based on alternating minimisation and splitting techniques is developed for the solution of the problem and tested on appropriately designed synthetic data sets. For those we compare the results to those of standard EM reconstructions and investigate the effects of Poisson noise in the data.

  5. Simultaneous CT and SPECT tomography using CZT detectors

    DOEpatents

    Paulus, Michael J.; Sari-Sarraf, Hamed; Simpson, Michael L.; Britton, Jr., Charles L.

    2002-01-01

    A method for simultaneous transmission x-ray computed tomography (CT) and single photon emission tomography (SPECT) comprises the steps of: injecting a subject with a tracer compound tagged with a .gamma.-ray emitting nuclide; directing an x-ray source toward the subject; rotating the x-ray source around the subject; emitting x-rays during the rotating step; rotating a cadmium zinc telluride (CZT) two-sided detector on an opposite side of the subject from the source; simultaneously detecting the position and energy of each pulsed x-ray and each emitted .gamma.-ray captured by the CZT detector; recording data for each position and each energy of each the captured x-ray and .gamma.-ray; and, creating CT and SPECT images from the recorded data. The transmitted energy levels of the x-rays lower are biased lower than energy levels of the .gamma.-rays. The x-ray source is operated in a continuous mode. The method can be implemented at ambient temperatures.

  6. Adaptive SPECT imaging with crossed-slit apertures

    NASA Astrophysics Data System (ADS)

    Durko, Heather L.; Furenlid, Lars R.

    2014-09-01

    Preclinical single-photon emission computed tomography (SPECT) is an essential tool for studying the pro-gression, response to treatment, and physiological changes in small animal models of human disease. The wide range of imaging applications is often limited by the static design of many preclinical SPECT systems. We have developed a prototype imaging system that replaces the standard static pinhole aperture with two sets of movable, keel-edged copper-tungsten blades configured as crossed (skewed) slits. These apertures can be positioned independently between the object and detector, producing a continuum of imaging configurations in which the axial and transaxial magnifications are not constrained to be equal. We incorporated a megapixel silicon double-sided strip detector to permit ultrahigh-resolution imaging. We describe the configuration of the adjustable slit aperture imaging system and discuss its application toward adaptive imaging, and reconstruction techniques using an accurate imaging forward model, a novel geometric calibration technique, and a GPU-based ultra-high-resolution reconstruction code.

  7. Myocardial Perfusion SPECT Imaging in Patients after Percutaneous Coronary Intervention.

    PubMed

    Georgoulias, Panagiotis; Valotassiou, Varvara; Tsougos, Ioannis; Demakopoulos, Nikolaos

    2010-05-01

    Coronary artery disease (CAD) is the most prevalent form of cardiovascular disease affecting about 13 million Americans, while more than one million percutaneous transluminal intervention (PCI) procedures are performed annually in the USA. The relative high occurrence of restenosis, despite stent implementation, seems to be the primary limitation of PCI. Over the last decades, single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI), has proven an invaluable tool for the diagnosis of CAD and patients' risk stratification, providing useful information regarding the decision about revascularization and is well suited to assess patients after intervention. Information gained from post-intervention MPI is crucial to differentiate patients with angina from those with exo-cardiac chest pain syndromes, to assess peri-intervention myocardial damage, to predict-detect restenosis after PCI, to detect CAD progression in non-revascularized vessels, to evaluate the effects of intervention if required for occupational reasons and to evaluate patients' long-term prognosis. On the other hand, chest pain and exercise electrocardiography are largely unhelpful in identifying patients at risk after PCI.Although there are enough published data demonstrating the value of myocardial perfusion SPECT imaging in patients after PCI, there is still debate on whether or not these tests should be performed routinely.

  8. Onboard functional and molecular imaging: A design investigation for robotic multipinhole SPECT

    SciTech Connect

    Bowsher, James Giles, William; Yin, Fang-Fang; Yan, Susu; Roper, Justin

    2014-01-15

    Purpose: Onboard imaging—currently performed primarily by x-ray transmission modalities—is essential in modern radiation therapy. As radiation therapy moves toward personalized medicine, molecular imaging, which views individual gene expression, may also be important onboard. Nuclear medicine methods, such as single photon emission computed tomography (SPECT), are premier modalities for molecular imaging. The purpose of this study is to investigate a robotic multipinhole approach to onboard SPECT. Methods: Computer-aided design (CAD) studies were performed to assess the feasibility of maneuvering a robotic SPECT system about a patient in position for radiation therapy. In order to obtain fast, high-quality SPECT images, a 49-pinhole SPECT camera was designed which provides high sensitivity to photons emitted from an imaging region of interest. This multipinhole system was investigated by computer-simulation studies. Seventeen hot spots 10 and 7 mm in diameter were placed in the breast region of a supine female phantom. Hot spot activity concentration was six times that of background. For the 49-pinhole camera and a reference, more conventional, broad field-of-view (FOV) SPECT system, projection data were computer simulated for 4-min scans and SPECT images were reconstructed. Hot-spot localization was evaluated using a nonprewhitening forced-choice numerical observer. Results: The CAD simulation studies found that robots could maneuver SPECT cameras about patients in position for radiation therapy. In the imaging studies, most hot spots were apparent in the 49-pinhole images. Average localization errors for 10-mm- and 7-mm-diameter hot spots were 0.4 and 1.7 mm, respectively, for the 49-pinhole system, and 3.1 and 5.7 mm, respectively, for the reference broad-FOV system. Conclusions: A robot could maneuver a multipinhole SPECT system about a patient in position for radiation therapy. The system could provide onboard functional and molecular imaging with 4-min

  9. The AAPM/RSNA physics tutorial for residents. Physics of SPECT.

    PubMed

    Tsui, B M

    1996-01-01

    Single-photon emission computed tomography (SPECT) provides three-dimensional (3D) image information about the distribution of a radiopharmaceutical injected into the patient for diagnostic purposes. By combining conventional scintigraphic and computed tomographic methods, SPECT images present 3D functional information about the patient in more detail and higher contrast than found in planar scintigrams. A typical SPECT system consists of one or more scintillation cameras that acquire multiple two-dimensional planar projection images around the patient. The projection data are reconstructed into 3D images. The collimator of the scintillation camera has substantial effects on the spatial resolution and detection efficiency of the SPECT system. Physical factors such as photon attenuation and scatter affect the quantitative accuracy and quality of SPECT images, and various methods have been developed to compensate for these image-degrading effects. In myocardial SPECT, an important application of SPECT, recent use of attenuation compensation methods has provided images with reduced artifacts and distortions caused by the non-uniform attenuation in the chest region and by the diaphragmatic and breast attenuation. Attenuation-compensated myocardial SPECT images have the potential to improve clinical diagnosis by reducing the false-positive and false-negative detection of myocardial defects. In the future, further improvement in SPECT images will be realized from the continuous development of new radio-pharmaceuticals for new clinical applications, instrumentation with high spatial resolution and detection efficiency, and image reconstruction algorithms and compensation methods that reduce the image-degrading effects of the collimator-detector, attenuation, and scatter.

  10. Inverse bremsstrahlung heating rate in xenon clusters in the eikonal approximation

    SciTech Connect

    Dey, R.; Roy, A. C.

    2013-03-15

    We report inverse bremsstrahlung (IB) heating rates in the eikonal approximation (EA). The present analysis is performed using the plasma-screened Rogers and Debye potentials for Xe clusters with two different charge states (6 and 10). We compare the eikonal results with the first Born approximation (FBA) and classical-simulation (CL-sim) (Moll et al., Phys. Plasmas 19, 033303 (2012)) calculations for clusters in infrared light. Calculations have been performed for the field strength of 2.6 Multiplication-Sign 10{sup 8} V/cm. We find that compared to the FBA and CL-sim methods, the IB heating rate in the EA is less sensitive to the choice of the two potentials considered here. The present EA calculation shows that the influence of the inner structure of atomic ion on the heating rate is more prominent for the smaller ion charge (Xe{sup 6+}). In the case of low laser field approximation based on the elastic transport cross sections, it is seen that in contrast to the FBA and classical methods, the heating rate predicted by the EA does not deviate much all over the range of mean kinetic energy of electrons (20-500 eV) considered here for both the charge states of xenon (Xe{sup 6+} and Xe{sup 10+}). Furthermore, for the Rogers potential, EA is found to be in closer agreement with the classical method than the FBA. We also compare the results of the IB heating rate using the present and low-field approximation approaches to the above three methods and observe that the magnitudes of the IB heating rate calculated in the low field approximation are, in general, higher than the corresponding values predicted by the present approach for both the electron-ion potentials.

  11. Virtual and bremsstrahlung corrections to b→dl+l- in the standard model

    NASA Astrophysics Data System (ADS)

    Asatrian, H. M.; Bieri, K.; Greub, C.; Walker, M.

    2004-04-01

    We present the calculation of the virtual and bremsstrahlung corrections of O(αs) to the matrix elements . This is the missing piece in the full next-to-next-to-leading logarithmic (NNLL) results for various observables associated with the process B→Xdl+l-, such as the branching ratio, the CP-rate asymmetry, and the forward-backward asymmetry. This paper is an extension of analogous calculations done by some of us for the process B→Xsl+l-. As the contributions of the diagrams induced by the four-quark operators Ou1 and Ou2 with a u quark running in the quark loop are strongly Cabibbo-Kobayashi-Maskawa suppressed, they were omitted in the analysis of B→Xsl+l-. This is no longer possible for B→Xdl+l-, as the corresponding contributions are not suppressed. The main new work therefore consists of calculating the O(αs) corrections to . In this paper we restrict ourselves to the range 0.05⩽s/m2b⩽0.25 (s is the invariant mass of the lepton pair), which lies above the ρ and ω resonances and below the J/ψ resonance. We present the analytic results for the mentioned observables related to the process B→Xdl+l- as expansions in the small parameters ŝ=s/m2b, z=m2c/m2b, and s/(4m2c). In the phenomenological analysis at the end of the paper we discuss the impact of the NNLL corrections on the observables mentioned above.

  12. Black-hole bremsstrahlung and the efficiency of mass-energy radiative transfer

    SciTech Connect

    Oliveira, H. P. de; Soares, I. Damiao; Tonini, E. V.

    2008-08-15

    We present results from numerical evolution of a boosted black hole, perturbed nonlinearly by an axisymmetric distribution of matter in the realm of Robinson-Trautman spacetimes. Characteristic initial data for the system were constructed and the Robinson-Trautmann equation was integrated for these data using a numerical code based on the Galerkin-collocation method. The emission of gravitational waves by the system is typical of bremsstrahlung at early times, a consequence of the deceleration of the black hole as it interacts with the perturbation; part of the perturbation is radiated away and another part is absorbed into the hole. The angular pattern evolves to the quadrupole form for later times. The final configuration is a black hole in motion with larger (Bondi) rest mass and smaller boost parameter. The efficiency {delta} of mass-energy extraction by gravitational wave emission was also computed. The relation of {delta} to the mass of the remnant black hole satisfies a nonextensive thermostatistics distribution with entropic index q{approx_equal}1/2. The result extends analytical evaluations based on the linearized theory of gravitational wave emission. For each initial boost parameter, there always exists a (large) value of the perturbation parameter A{sub 0} for which the momentum of the remnant black hole has opposite sign to that of the unperturbed black hole, due to the strong deceleration during the process of gravitational wave emission. The temporal wave form is that of an initial burst and we evaluate that for a large range of A{sub 0} the process corresponds to a high power output in the initial dominant pulse.

  13. Determination of Endpoint Energy and Bremsstrahlung Spectra for High-Energy Radiation-Therapy Beams

    NASA Astrophysics Data System (ADS)

    Landry, Danny Joe

    Few attempts have been made to experimentally determine thick-target bremsstrahlung spectra of megavoltage therapy beams. For spectral studies using the Compton scattering technique, sodium iodine (NaI) detectors with relatively poor energy resolution have been used. Other experimental techniques for determining spectra are generally not suited for a clinical environment with the inherent time and space constraints. To gather more spectral information than previously obtained in the region near the endpoint energy, the use of a high-resolution intrinsic-germanium (Ge) detector was proposed. A response function matrix was determined from experimentally obtained pulse height distributions on the multichannel analyzer. The distributions were for nine various monoenergetic sources between 280 adn 1525 keV. The response function was used to convert the measured pulse height distributions to photon flux spectra using an iterative approximation technique with a computer. Photon flux spectra from the Sagittaire Linear Accelerator were obtained at average-electron endpoint energies of 15, 20, and 25 MeV. Two spectra were measured at the 25 MeV setting; one spectrum was measured along the central axis and one spectrum at 4(DEGREES) off axis. Photon spectra were also obtained for a Van de Graaff generator at the nominal endpoint energies of 2.2, 2.35, and 2.5 MeV. The results for both the linac and the Van de Graaff generator were compared with theoretical spectra and previously measured spectra where available. Also, photon spectra from a Theratron-80 (('60)Co) unit were determined for three field sizes and for a 10 x 10 cm. field with a lucite tray or a 45(DEGREES) wedge in the beam. The resulting spectra were compared to previously measured ('60)Co spectra.

  14. Evaluation of S-values and dose distributions for {sup 90}Y, {sup 131}I, {sup 166}Ho, and {sup 188}Re in seven lobes of the rat liver

    SciTech Connect

    Xie Tianwu; Liu Qian; Zaidi, Habib

    2012-03-15

    Purpose: Rats have been widely used in radionuclide therapy research for the treatment of hepatocellular carcinoma (HCC). This has created the need to assess rat liver absorbed radiation dose. In most dose estimation studies, the rat liver is considered as a homogeneous integrated target organ with a tissue composition assumed to be similar to that of human liver tissue. However, the rat liver is composed of several lobes having different anatomical and chemical characteristics. To assess the overall impact on rat liver dose calculation, the authors use a new voxel-based rat model with identified suborgan regions of the liver. Methods: The liver in the original cryosectional color images was manually segmented into seven individual lobes and subsequently integrated into a voxel-based computational rat model. Photon and electron particle transport was simulated using the MCNPX Monte Carlo code to calculate absorbed fractions and S-values for {sup 90}Y, {sup 131}I, {sup 166}Ho, and {sup 188}Re for the seven liver lobes. The effect of chemical composition on organ-specific absorbed dose was investigated by changing the chemical composition of the voxel filling liver material. Radionuclide-specific absorbed doses at the voxel level were further assessed for a small spherical hepatic tumor. Results: The self-absorbed dose for different liver lobes varied depending on their respective masses. A maximum difference of 3.5% was observed for the liver self-absorbed fraction between rat and human tissues for photon energies below 100 keV. {sup 166}Ho and {sup 188}Re produce a uniformly distributed high dose in the tumor and relatively low absorbed dose for surrounding tissues. Conclusions: The authors evaluated rat liver radiation doses from various radionuclides used in HCC treatments using a realistic computational rat model. This work contributes to a better understanding of all aspects influencing radiation transport in organ-specific radiation dose evaluation for

  15. Study of influence of plastic scintillators thicknesses to detect Beta particles and Gamma radiation by means of spectral analysis of {sup 90}Sr, {sup 90}Y and {sup 137}Cs sources

    SciTech Connect

    Cardenas, Jose Patricio Nahuel; Filho, Tufic Madi; Pereira, Maria da Conceicao Costa; Santos, Brianna B. dos; Correa, Eduardo de L.; Santos, Lucas Rodrigues dos; Lopes, Anderson Figueredo; Silva, Alexandre F.P. da; Santos, Diogo F. dos; Camilo, Douglas de S.; Purgato, Rafael T.; Aredes, Vitor O.G.

    2015-07-01

    The Nuclear and Energy Research Institute - IPEN, offers post-graduate programs, namely: Nuclear Technology - Applications (TNA), Nuclear Technology - Materials (TNM), Nuclear Technology - Reactors (TNR). The Institute programs mission is to form expert technicians, physicists and engineers with a strong knowledge in their discipline to work in the nuclear area. The course: 'Theoretical Fundamentals and Practices of the Instrumentation used in Nuclear Data Acquisition' covers the use of laboratory nuclear instrumentation and the accomplishment of experiments to obtain nuclear parameters. One of these experimental exercises is object of this work: 'Study of influence of plastic scintillators to detect Beta particles and Gamma radiation by means of spectral analysis of {sup 90}Sr, {sup 90}Y and {sup 137}Cs sources'. The use of scintillators plastic for the detection has the advantage of low cost, high mechanical strength, is not hygroscopic and can be manufactured in large volumes. This work aims to present the analysis of relative efficiency of detection of plastic scintillators of various thicknesses for beta particles and gamma radiation by the spectrum of {sup 137}Cs and {sup 90}Sr. Due to lack of resolution of the detectors plastic scintillators we worked with relative efficiency. The evaluation was done by reading deposited energy, using the software MAESTRO, for each detector thickness. For beta particles was observed an ideal thickness around 3 mm and the better photon efficiency was observed with increasing the thickness of the detector. The present experiment does not intend to establish a new technique for this subject: it solely aims student's practical exercises in nuclear properties of elements and detectors being part of the nuclear experimental course. (authors)

  16. Relative Biologic Effects of Low-Dose-Rate {alpha}-Emitting {sup 227}Th-Rituximab and {beta}-Emitting {sup 90}Y-Tiuexetan-Ibritumomab Versus External Beam X-Radiation

    SciTech Connect

    Dahle, Jostein Bruland, Oyvind S.; Larsen, Roy H.

    2008-09-01

    Purpose: To determine the relative biologic effects (RBE) of {alpha}-particle radiation from {sup 227}Th-rituximab and of {beta}-radiation from {sup 90}Y-tiuexetan-ibritumomab (Zevalin) compared with external beam X-radiation in the Raji lymphoma xenograft model. Methods and Materials: Radioimmunoconjugates were administered intravenously in nude mice with Raji lymphoma xenografts at different levels of activity. Absorbed dose to tumor was estimated by separate biodistribution experiments for {sup 227}Th-rituximab and Zevalin. Tumor growth was measured two to three times per week after injection or X-radiation. Treatment-induced increase in growth delay to reach tumor volumes of 500 and 1,000 mm{sup 3}, respectively, was used as an end point. Results: The absorbed radiation dose-rate in tumor was slightly more than 0.1 Gy/d for the first week following injection of {sup 227}Th-rituximab, and thereafter gradually decreased to 0.03 Gy/d at 21 days after injection. For treatment with Zevalin the maximum dose-rate in tumor was achieved already 6 h after injection (0.2 Gy/d), and thereafter decreased to 0.01 Gy/d after 7 days. The relative biologic effect was between 2.5 and 7.2 for {sup 227}Th-rituximab and between 1 and 1.3 for Zevalin. Conclusions: Both at low doses and low-dose-rates, the {sup 227}Th-rituximab treatment was more effective per absorbed radiation dose unit than the two other treatments. The considerable effect at low doses suggests that the best way to administer low-dose-rates, {alpha}-emitting radioimmunoconjugates is via multiple injections.

  17. A high-sensitivity small animal SPECT system

    NASA Astrophysics Data System (ADS)

    Mitchell, Gregory S.; Cherry, Simon R.

    2009-03-01

    Medical imaging using single gamma-ray-emitting radionuclides typically makes use of parallel hole collimators or pinholes in order to achieve good spatial resolution. However, a tradeoff in sensitivity is inherent in the use of a collimator, and modern preclinical single photon emission computed tomography (SPECT) systems detect a very small fraction of emitted gamma rays, often less than 0.1%. A system for small animal SPECT imaging which uses no collimators could potentially achieve very high sensitivity—several tens of percent—with reasonably sized detectors. This would allow two significant improvements in preclinical studies: images could be obtained more rapidly, allowing higher throughput for screening applications, or for dynamic processes to be observed with very good time resolution; and images could be obtained with less radioactive tracer, making possible the in vivo imaging of low-capacity receptor systems, aiding research into new tracer compounds, and reducing the cost and easing the regulatory burden of an experiment. Of course, a system with no collimator will not be able to approach the submillimeter spatial resolutions produced by the most advanced pinhole and collimated systems, but a high-sensitivity system with resolution of order 1 cm could nonetheless find significant and new use in the many molecular imaging applications which do not require good spatial resolution—for example, screening applications for drug development or new imaging agents. Rather than as an alternative to high-resolution SPECT systems, the high-sensitivity system is proposed as a radiotracer alternative to optical imaging for small animals. We have developed a prototype system for mouse imaging applications. The scanner consists of two large, thin, closely spaced scintillation detectors. Simulation studies indicate that a FWHM spatial resolution of 7 mm is possible. In an in vivo mouse imaging study using the 99mTc labeled tracer MAG-3, the sensitivity of the

  18. Evaluation of Hospitalized Intractable Epileptic Children with SPECT Scan in Ahvaz, South West of Iran

    PubMed Central

    Ahmadi, Faramarz; Malekian, Arash; Davoodzadeh, Hannaneh; Kabirinia, Hossein

    2016-01-01

    Introduction Seizures are the most frequent neurologic disorder seen in childhood. Epilepsy is a group of disorders that includes an abnormally increased susceptibility to seizures. Aim To examine the effectiveness of SPECT (Single Photon Emission Computerized Tomography) in detecting seizure foci in 21 Iranian children who had medically refractory epilepsy. Materials and Methods Children between 2 to 15 years of age with uncontrolled seizures were investigated using SPECT scan as a standardized protocol. Results In 16 cases (76.2%), likely seizure foci were evident, as were seen in the form of decreased regional blood flow, while in 5 cases (23.8%), SPECT scan results were normal. Left temporal lobe was the most common area which had decreased regional blood flow. Conclusion SPECT scan can potentially be used to investigate children with uncontrolled seizures. PMID:27891419

  19. A SPECT study in internal carotid artery occlusion: Discrepancies between flow image and neurologic deficits

    SciTech Connect

    Moriwaki, H.; Hougaku, H.; Matsuda, I.; Kusunoki, M.; Shirai, J. )

    1989-08-01

    A SPECT (single photon emission computed tomography) study in internal carotid artery (ICA) occlusion was performed in 6 patients. The validity of iodoamphetamine (IMP) SPECT study in the evaluation of cerebral blood flow (CBF) or neurologic function is still controversial. In this study, the authors showed several cases in whom SPECT images of brain were not compatible with their neurologic deficits. In 2 typical cases, a large low-density area was observed in the non-dominant hemisphere in computed tomography (CT) scan, but no apparent motor-sensory deficits in left limbs were present. In these patients, SPECT study also revealed flow reduction in the affected side of the brain. So there was a possibility that an IMP brain image could not always reflect CBF, which maintains neurologic function of the brain.

  20. Clinical application of SPECT in adrenal imaging with iodine-131 6 beta-iodomethyl-19-norcholesterol

    SciTech Connect

    Ishimura, J.; Kawanaka, M.; Fukuchi, M.

    1989-04-01

    Forty-one patients with or without adrenocortical disorders were studied to evaluate the clinical usefulness of SPECT in adrenal imaging with I-131 Adosterol. In the SPECT images from this study, all glands with either normally functioning or hyperfunctioning adrenal cortices could be detected, while those glands with hypofunctioning adrenal cortices could not be detected. Particularly in transaxial and sagittal slices, the adrenal gland was identified posteriorly and was clearly distinguished from the gallbladder. In preliminary results using SPECT by a standard method, uptake in 68 detectable glands ranged from 1.7% to 4.9% in four glands with Cushing's syndrome, from 1.1% to 1.3% in seven glands with primary aldosteronism, and were distributed below 1.0% in the remaining glands with normally functioning adrenal cortices. These data show that it is possible to evaluate the adrenocortical functioning status simply by analyzing the SPECT images of the adrenal.

  1. NMF-Based Analysis of SPECT Brain Images for the Diagnosis of Alzheimer's Disease

    NASA Astrophysics Data System (ADS)

    Padilla, Pablo; Górriz, Juan-Manuel; Ramírez, Javier; Lang, Elmar; Chaves, Rosa; Segovia, Fermin; Álvarez, Ignacio; Salas-González, Diego; López, Miriam

    This paper offers a computer-aided diagnosis (CAD) technique for early diagnosis of Alzheimer's disease (AD) by means of single photon emission computed tomography (SPECT) image classification. The SPECT database for different patients is analyzed by applying the Fisher discriminant ratio (FDR) and non-negative matrix factorization (NMF) for the selection and extraction of the most significative features of each patient SPECT data, in order to reduce the large dimensionality of the input data and the problem of the curse of dimensionality, extracting score features. The NMF-transformed set of data, with reduced number of features, is classified by means of support vector machines (SVM) classification. The proposed NMF+SVM method yields up to 94% classification accuracy, thus becoming an accurate method for SPECT image classification. For the sake of completeness, comparison between conventional PCA+SVM method and the proposed method is also provided.

  2. Combined SPECT/CT and PET/CT for breast imaging

    NASA Astrophysics Data System (ADS)

    Russo, Paolo; Larobina, Michele; Di Lillo, Francesca; Del Vecchio, Silvana; Mettivier, Giovanni

    2016-02-01

    In the field of nuclear medicine imaging, breast imaging for cancer diagnosis is still mainly based on 2D imaging techniques. Three-dimensional tomographic imaging with whole-body PET or SPECT scanners, when used for imaging the breast, has performance limits in terms of spatial resolution and sensitivity, which can be overcome only with a dedicated instrumentation. However, only few hybrid imaging systems for PET/CT or SPECT/CT dedicated to the breast have been developed in the last decade, providing complementary functional and anatomical information on normal breast tissue and lesions. These systems are still under development and clinical trials on just few patients have been reported; no commercial dedicated breast PET/CT or SPECT/CT is available. This paper reviews combined dedicated breast PET/CT and SPECT/CT scanners described in the recent literature, with focus on their technological aspects.

  3. 99mTc-HMPAO perfusion SPECT/CT in the diagnosis of brain death.

    PubMed

    Derlin, Thorsten; Weiberg, Desiree

    2016-01-01

    This report describes a case of brain death (BD) evaluated by 99mTc-hexamethylpropylene amine oxime (HMPAO) single photon emission tomography/computed tomography (SPECT/CT). A 16-year-old boy with a history of rapid unexpected brain herniation due to pilocytic astrocytoma underwent 99mTc-HMPAO SPECT/CT for evaluation of brain death in the context of organ donation. Flow images demonstrated lack of blood flow to the brain, and delayed images showed absence of demonstrable radionuclide activity within the brain. SPECT/CT confirmed absence of tracer accumulation, and was deemed helpful for evaluation of the brain stem. 99mTc-HMPAO SPECT/CT is a valuable tool enabling imaging-based confirmation of BD.

  4. Modeling of the Sensitivity of Fan-Beam Collimation in Spect Imaging

    DTIC Science & Technology

    2007-11-02

    dB by the manufacturer and by projection measurements of a uniform flood source. 2 THEORY 2.1 Ideal collimation Consider a schematic representation of...MODELING OF THE SENSITIVITY OF FAN-BEAM COLLIMATION IN SPECT IMAGING Michel Koolex, Yves D’Asselerx, Stefaan Vandenberghex, Rik Van de Wallex, Koen...Nuclear Medicine Division, University Hospital of Ghent, De Pintelaan 185 B-9000 Ghent, Belgium Abstract An essential feature of SPECT imaging is

  5. Radiation risk and protection of patients in clinical SPECT/CT.

    PubMed

    Brix, Gunnar; Nekolla, Elke A; Borowski, Markus; Noßke, Dietmar

    2014-05-01

    Clinical studies have demonstrated that hybrid single photon emission computed tomography (SPECT)/CT for various diagnostic issues has an added value as compared to SPECT alone. However, the combined acquisition of functional and anatomical images can substantially increase radiation exposure to patients, in particular when using a hybrid system with diagnostic CT capabilities. It is, therefore, essential to carefully balance the diagnostic needs and radiation protection requirements. To this end, the evidence on health effects induced by ionizing radiation is outlined. In addition, the essential concepts for estimating radiation doses and lifetime attributable cancer risks associated with SPECT/CT examinations are presented taking into account both the new recommendations of the International Commission on Radiological Protection (ICRP) as well as the most recent radiation risk models. Representative values of effective dose and lifetime attributable risk are reported for ten frequently used SPECT radiopharmaceuticals and five fully diagnostic partial-body CT examinations. A diagnostic CT scan acquired as part of a combined SPECT/CT examination contributes considerably to, and for some applications even dominates, the total patient exposure. For the common SPECT and CT examinations considered in this study, the lifetime attributable risk of developing a radiation-related cancer is less than 0.27 %/0.37 % for men/women older than 16 years, respectively, and decreases markedly with increasing age at exposure. Since there is no clinical indication for a SPECT/CT examination unless an emission scan has been indicated, the issue on justification comes down to the question of whether it is necessary to additionally acquire a low-dose CT for attenuation correction and anatomical localization of tracer uptake or even a fully diagnostic CT. In any case, SPECT/CT studies have to be optimized, e.g. by adapting dose reduction measures from state-of-the-art CT practice, and

  6. Hotspot quantification of myocardial focal tracer uptake from molecular targeted SPECT/CT images: experimental validation

    NASA Astrophysics Data System (ADS)

    Liu, Yi-Hwa; Sahul, Zakir; Weyman, Christopher A.; Ryder, William J.; Dione, Donald P.; Dobrucki, Lawrence W.; Mekkaoui, Choukri; Brennan, Matthew P.; Hu, Xiaoyue; Hawley, Christi; Sinusas, Albert J.

    2008-03-01

    We have developed a new single photon emission computerized tomography (SPECT) hotspot quantification method incorporating extra cardiac activity correction and hotspot normal limit estimation. The method was validated for estimation accuracy of myocardial tracer focal uptake in a chronic canine model of myocardial infarction (MI). Dogs (n = 4) at 2 weeks post MI were injected with Tl-201 and a Tc-99m-labeled hotspot tracer targeted at matrix metalloproteinases (MMPs). An external point source filled with Tc-99m was used for a reference of absolute radioactivity. Dual-isotope (Tc-99m/Tl-201) SPECT images were acquired simultaneously followed by an X-ray CT acquisition. Dogs were sacrificed after imaging for myocardial gamma well counting. Images were reconstructed with CT-based attenuation correction (AC) and without AC (NAC) and were quantified using our quantification method. Normal limits for myocardial hotspot uptake were estimated based on 3 different schemes: maximum entropy, meansquared-error minimization (MSEM) and global minimization. Absolute myocardial hotspot uptake was quantified from SPECT images using the normal limits and compared with well-counted radioactivity on a segment-by-segment basis (n = 12 segments/dog). Radioactivity was expressed as % injected dose (%ID). There was an excellent correlation (r = 0.78-0.92) between the estimated activity (%ID) derived using the SPECT quantitative approach and well-counting, independent of AC. However, SPECT quantification without AC resulted in the significant underestimation of radioactivity. Quantification using SPECT with AC and the MSEM normal limit yielded the best results compared with well-counting. In conclusion, focal myocardial "hotspot" uptake of a targeted radiotracer can be accurately quantified in vivo using a method that incorporates SPECT imaging with AC, an external reference, background scatter compensation, and a suitable normal limit. This hybrid SPECT/CT approach allows for the serial

  7. Investigation of Metastatic Breast Tumor Heterogeneity and Progression Using Dual Optical/SPECT Imaging

    DTIC Science & Technology

    2007-05-01

    parallel-hole collimator or coded aperture are better suited for small animal imaging. Front end computer – 64 bit Athlon FX Gigabit ethernet switch D...our capability to detect millimeter or sub-millimeter metastases in mice by light emission. To this end we have used Light Emission Tomography (LET...Tomography (SPECT), and to this end we have developed a new form of micro-SPECT based on cooled, electron-multiplied Charge-Coupled Devices (EMCCDs) with

  8. U-SPECT-BioFluo: an integrated radionuclide, bioluminescence, and fluorescence imaging platform

    PubMed Central

    2014-01-01

    Background In vivo bioluminescence, fluorescence, and single-photon emission computed tomography (SPECT) imaging provide complementary information about biological processes. However, to date these signatures are evaluated separately on individual preclinical systems. In this paper, we introduce a fully integrated bioluminescence-fluorescence-SPECT platform. Next to an optimization in logistics and image fusion, this integration can help improve understanding of the optical imaging (OI) results. Methods An OI module was developed for a preclinical SPECT system (U-SPECT, MILabs, Utrecht, the Netherlands). The applicability of the module for bioluminescence and fluorescence imaging was evaluated in both a phantom and in an in vivo setting using mice implanted with a 4 T1-luc + tumor. A combination of a fluorescent dye and radioactive moiety was used to directly relate the optical images of the module to the SPECT findings. Bioluminescence imaging (BLI) was compared to the localization of the fluorescence signal in the tumors. Results Both the phantom and in vivo mouse studies showed that superficial fluorescence signals could be imaged accurately. The SPECT and bioluminescence images could be used to place the fluorescence findings in perspective, e.g. by showing tracer accumulation in non-target organs such as the liver and kidneys (SPECT) and giving a semi-quantitative read-out for tumor spread (bioluminescence). Conclusions We developed a fully integrated multimodal platform that provides complementary registered imaging of bioluminescent, fluorescent, and SPECT signatures in a single scanning session with a single dose of anesthesia. In our view, integration of these modalities helps to improve data interpretation of optical findings in relation to radionuclide images. PMID:25386389

  9. SPECT myocardial perfusion imaging for the assessment of left ventricular mechanical dyssynchrony

    PubMed Central

    Chen, Ji; Garcia, Ernest V.; Bax, Jeroen J.; Iskandrian, Ami E.; Borges-Neto, Salvador; Soman, Prem

    2012-01-01

    Phase analysis of gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is an evolving technique for measuring LV mechanical dyssynchrony. Since its inception in 2005, it has undergone considerable technical development and clinical evaluation. This article reviews the background, the technical and clinical characteristics, and evolving clinical applications of phase analysis of gated SPECT MPI in patients requiring cardiac resynchronization therapy or implantable cardioverter defibrillator therapy and in assessing LV diastolic dyssynchrony. PMID:21567281

  10. Comparison of measured and theoretical inverse bremsstrahlung and photoionization absorption of infrared radiation in a H-He plasma.

    NASA Technical Reports Server (NTRS)

    Billman, K. W.; Stallcop, J. R.; Rowley, P. D.; Presley, L. L.

    1972-01-01

    The absorption coefficients of 1.15- and 3.39-micrometer radiation for a homogeneous H-He plasma have been measured in a temperature and electron density range where the major absorption mechanisms are electron-ion inverse bremsstrahlung and neutral-atom photoionization. Measurements were made behind both the incident and reflected shock waves in a driven tube by recording the laser intensity transmitted along the tube diameter as a function of time. The measured values compare well with those obtained from theoretical calculations for a gas in thermodynamic equilibrium.

  11. The Virtual Correction to Bremsstrahlung in Results High-Energy e+e- Annihilation:. Comparison of Exact Results

    NASA Astrophysics Data System (ADS)

    Yost, S. A.; Glosser, C.; Jadach, S.; Ward, B. F. L.

    2005-04-01

    We have compared the virtual corrections to single hard bremsstrahlung as calculated by S. Jadach, M. Melles, B.F.L. Ward and S.A. Yost to several other expressions. The most recent of these comparisons is to the leptonic tensor calculated by J.H. Kühn and G. Rodrigo for radiative return. Agreement is found to within 10-5 or better, as a fraction of the Born cross section, for most of the range of photon energies. The massless limits have been shown to agree analytically to NLL order.

  12. A Modified Post Processing Correction Matrix For SPECT

    NASA Astrophysics Data System (ADS)

    Macey, D. J.; DeNardo, G. L.; DeNardo, S. J.; Seibert, J. A.

    1986-01-01

    A post reconstruction method of attenuation compensation for Single Photon Emission Computed Tomography (SPECT) has been investigated that offers a new approach to the problem of quantitation. A modified correction matrix is generated for attenuation compensation in which the Linear Attenuation Coefficient (LAC) for each pixel is assigned a value depending on the radial distance of the pixel from the true section boundary. Attenuation compensation of transverse section images of small and large volume sources of Tc-99m in phantoms using this modified matrix indicated that a known quantity of radionuclide could be determined to better than 10%. The scatter fraction was estimated as the difference in the corrected section images using a multiplicative matrix generated with a constant LAC for each pixel and the modified matrix proposed in this report.

  13. High resolution SPECT, small deep infarcts and diaschisis.

    PubMed Central

    Bowler, J V; Costa, D C; Jones, B E; Steiner, T J; Wade, J P

    1992-01-01

    Eighteen cases of lacunar infarction are presented. Six of these cases had a purely motor clinical deficit. All the cases were studied by serial high resolution SPECT (single photon emission computerized tomography) using 99Tcm HMPAO. The degree and extent of the changes in cerebral perfusion consistent with diaschisis were noted and these compared with the severity of the clinical deficit at presentation and over time. No significant correlation between diaschisis and the clinical state was found at any stage. The nature, aetiology and importance of diaschisis are discussed and it is suggested that caution should be exercised in attributing clinical features to diaschisis simply because it may be present. Images Figure 1. Figure 2. PMID:1556715

  14. PET/SPECT imaging agents for neurodegenerative diseases

    PubMed Central

    Zhu, Lin; Ploessl, Karl; Kung, Hank F.

    2014-01-01

    Single photon emission computed tomography (SPECT) or positron emission computed tomography (PET) imaging agents for neurodegenerative disease have a significant impact on clinical diagnosis and patient care. The examples of Parkinson’s Disease (PD) and Alzheimer’s Disease (AD) imaging agents described in this paper provide a general view on how imaging agents, ie radioactive drugs, are selected, chemically prepared and applied in humans. Imaging the living human brain can provide unique information on the pathology and progression of neurodegenerative diseases, such as AD and PD. The imaging method will also facilitate preclinical and clinical trials of new drugs offering specific information related to drug binding sites in the brain. In the future, chemists will continue to play important roles in identifying specific targets, synthesizing target-specific probes for screening and ultimately testing them by in vitro and in vivo assays. PMID:24676152

  15. [Usefulness of SPECT images in helping radiologists understand brain diseases].

    PubMed

    Hayashida, K

    2001-04-01

    Nuclear brain imaging is able to show functional abnormalities of lesions that are not detectable by CT and MR images. The diagnostic keys of nuclear-imaging in terms of clinical usefulness are its early detection of lesions and determination of the efficacy of drug and surgical therapies. In dementic patients, F-18 FDG brain images can be diagnosed as Alzheimer's disease 12 months earlier than is possible on CT and MRI images, and can provide information for effective drug therapy. O-15 water CBF images can predict the effect of Nicholin by assessing transient increases in cerebral blood flow (CBF), thereby facilitating improvement in higher brain functions such as orientation. In stroke patients, brain SPECT images with Tc-99m HMPAO can predict fatal cerebral hemorrhage caused by anti-thrombic therapy by showing the decrease in count ratio (count ratio of infarcted to contralateral area of < 0.34) in the acute phase and identifying disruption of the blood brain barrier by showing hyperfixation in the subacute phase. Brain SPECT with I-123 IMP can also identify "misery" perfused areas resulting from reduced CBF and decreased vasoreactivity in the chronic phase. This criterion is utilized for patient selection for extracranial/intracranial bypass surgery, because patients with areas of poor perfusion might be indicated for such surgery. Since nuclear medicine images can accurately select candidates for drug or surgical therapies, they will be beneficial in reducing Medicare costs as well as in enhancing patients' quality of life as a result of the successful treatment. With the advancement of technology, nuclear medicine units that can simultaneously obtain CT images and can combine functional with anatomical images will provide more useful information for the diagnosis of brain disease.

  16. GATE: a simulation toolkit for PET and SPECT.

    PubMed

    Jan, S; Santin, G; Strul, D; Staelens, S; Assié, K; Autret, D; Avner, S; Barbier, R; Bardiès, M; Bloomfield, P M; Brasse, D; Breton, V; Bruyndonckx, P; Buvat, I; Chatziioannou, A F; Choi, Y; Chung, Y H; Comtat, C; Donnarieix, D; Ferrer, L; Glick, S J; Groiselle, C J; Guez, D; Honore, P F; Kerhoas-Cavata, S; Kirov, A S; Kohli, V; Koole, M; Krieguer, M; van der Laan, D J; Lamare, F; Largeron, G; Lartizien, C; Lazaro, D; Maas, M C; Maigne, L; Mayet, F; Melot, F; Merheb, C; Pennacchio, E; Perez, J; Pietrzyk, U; Rannou, F R; Rey, M; Schaart, D R; Schmidtlein, C R; Simon, L; Song, T Y; Vieira, J M; Visvikis, D; Van de Walle, R; Wieërs, E; Morel, C

    2004-10-07

    Monte Carlo simulation is an essential tool in emission tomography that can assist in the design of new medical imaging devices, the optimization of acquisition protocols and the development or assessment of image reconstruction algorithms and correction techniques. GATE, the Geant4 Application for Tomographic Emission, encapsulates the Geant4 libraries to achieve a modular, versatile, scripted simulation toolkit adapted to the field of nuclear medicine. In particular, GATE allows the description of time-dependent phenomena such as source or detector movement, and source decay kinetics. This feature makes it possible to simulate time curves under realistic acquisition conditions and to test dynamic reconstruction algorithms. This paper gives a detailed description of the design and development of GATE by the OpenGATE collaboration, whose continuing objective is to improve, document and validate GATE by simulating commercially available imaging systems for PET and SPECT. Large effort is also invested in the ability and the flexibility to model novel detection systems or systems still under design. A public release of GATE licensed under the GNU Lesser General Public License can be downloaded at http:/www-lphe.epfl.ch/GATE/. Two benchmarks developed for PET and SPECT to test the installation of GATE and to serve as a tutorial for the users are presented. Extensive validation of the GATE simulation platform has been started, comparing simulations and measurements on commercially available acquisition systems. References to those results are listed. The future prospects towards the gridification of GATE and its extension to other domains such as dosimetry are also discussed.

  17. Multipinhole SPECT helical scan parameters and imaging volume

    SciTech Connect

    Yao, Rutao Deng, Xiao; Wei, Qingyang; Dai, Tiantian; Ma, Tianyu; Lecomte, Roger

    2015-11-15

    Purpose: The authors developed SPECT imaging capability on an animal PET scanner using a multiple-pinhole collimator and step-and-shoot helical data acquisition protocols. The objective of this work was to determine the preferred helical scan parameters, i.e., the angular and axial step sizes, and the imaging volume, that provide optimal imaging performance. Methods: The authors studied nine helical scan protocols formed by permuting three rotational and three axial step sizes. These step sizes were chosen around the reference values analytically calculated from the estimated spatial resolution of the SPECT system and the Nyquist sampling theorem. The nine helical protocols were evaluated by two figures-of-merit: the sampling completeness percentage (SCP) and the root-mean-square (RMS) resolution. SCP was an analytically calculated numerical index based on projection sampling. RMS resolution was derived from the reconstructed images of a sphere-grid phantom. Results: The RMS resolution results show that (1) the start and end pinhole planes of the helical scheme determine the axial extent of the effective field of view (EFOV), and (2) the diameter of the transverse EFOV is adequately calculated from the geometry of the pinhole opening, since the peripheral region beyond EFOV would introduce projection multiplexing and consequent effects. The RMS resolution results of the nine helical scan schemes show optimal resolution is achieved when the axial step size is the half, and the angular step size is about twice the corresponding values derived from the Nyquist theorem. The SCP results agree in general with that of RMS resolution but are less critical in assessing the effects of helical parameters and EFOV. Conclusions: The authors quantitatively validated the effective FOV of multiple pinhole helical scan protocols and proposed a simple method to calculate optimal helical scan parameters.

  18. Pharmacokinetics of SPECT radiopharmaceuticals for imaging hypoxic tissues.

    PubMed

    Wiebe, L I; Stypinski, D

    1996-09-01

    Although hypoxia has been known for decades to play an important role in the outcome of radiotherapy in oncology, and inspite of the contribution of hypoxia to a myriad of pathologies that involve vascular disease, the selective imaging of hypoxic tissue has attained prominence only within the past decade. Contemporary research in the hypoxia imaging field is based largely on radiosensitizer research of the 1960's and 1970's. Early sensitizer research identified a family of nitro-organic compounds, the N-1 substituted 2-nitroimidazoles as candidate drugs. The early champion, and still the reference standard for therapeutic radiosensitization of hypoxic tumor cells is misonidazole (MISO). Its peripheral neurotoxicity led to failure in clinical studies, but its biological, biophysical and biochemical properties have been investigated in detail and serve as a basis for further design, not only of sensitizers, but of diagnostic radiopharmaceuticals for imaging tissue hypoxia. Pharmacokinetic characterization of radiopharmaceuticals, specifically radiopharmaceuticals for imaging tissue hypoxia, has not been a central theme in their development. The advent of PET, through which quantitative determinations first became possible, opened the field for both descriptive and analytical radiopharmacokinetic studies. In SPECT, however, this approach is still undergoing refinement. This paper addresses some of the underlying issues in radiopharmaceutical pharmacokinetics. There is a paucity of published radiopharmacokinetic data for SPECT hypoxia imaging agents. Consequently, the pharmacokinetic issues for MISO are presented as a basis for development of pharmacokinetics for the chemically-related imaging agents. Properties of an hypoxia marker are described from a pharmacokinetic viewpoint, a theoretical model for descriptive pharmacokinetics is introduced and finally, recent pharmacokinetic studies from our laboratory are described.

  19. Attenuation correction effects on SPECT/CT procedures: phantoms studies.

    PubMed

    Oliveira, M L; Seren, M E G; Rocha, F C; Brunetto, S Q; Ramos, C D; Button, V L S N

    2013-01-01

    Attenuation correction is widely used in SPECT/CT (Single Photon Emission Computed Tomography) procedures, especially for imaging of the thorax region. Different compensation methods have been developed and introduced into clinical practice. Most of them use attenuation maps obtained using transmission scanning systems. However, this gives extra dose of radiation to the patient. The purpose of this study was to identify when attenuation correction is really important during SPECT/CT procedures.For this purpose, we used Jaszczak phantom and phantom with three line sources, filled with technetium ((99m)-Tc), with scattering materials, like air, water and acrylic, in different detectors configurations. In all images acquired were applied analytic and iterative reconstruction algorithms; the last one with or without attenuation correction. We analyzed parameters such as eccentricity, contrast and spatial resolution in the images.The best reconstruction algorithm on average was iterative, for images with 128 × 128 and 64 × 64 matrixes. The analytical algorithm was effective only to improve eccentricity in 64 × 64 matrix and matrix in contrast 128 × 128 with low statistics. Turning to the clinical routine examinations, on average, for 128 × 128 matrix and low statistics counting, the best algorithm was the iterative, without attenuation correction,improving in 150% the three parameters analyzed and, for the same matrix size, but with high statistical counting, iterative algorithm with attenuation correction was 25% better than that without correction. We can conclude that using the iterative algorithm with attenuation correction in the water, and its extra dose given, is not justified for the procedures of low statistic counting, being relevant only if the intention is to prioritize contrast in acquisitions with high statistic counting.

  20. Automated coregistration and statistical analyses of SPECT brain images

    SciTech Connect

    Gong, W.; Devous, M.D.

    1994-05-01

    Statistical analyses of SPECT image data often require highly accurate image coregistration. Several image coregistration algorithms have been developed. The Pellizari algorithm (PA) uses the Powell technique to estimate transformation parameters between the {open_quotes}head{close_quotes} (model) and {open_quotes}hat{close_quotes} (images to be registered). Image normalization and good initial transformation parameters heavily affect the accuracy and speed of convergence of the PA. We have explored various normalization methods and found a simple technique that avoids most artificial edge effects and minimizes blurring of useful edges. We have tested the effects on accuracy and convergence speed of the PA caused by different initial transformation parameters. From these data, a modified PA was integrated into an automated coregistration system for SPECT brain images on the PRISM 3000S under X Windows. The system yields an accuracy of approximately 2 mm between model and registered images, and employs minimal user intervention through a simple graphic user interface. Data are automatically resliced, normalized and coregistered, with the user choosing only the slice range for inclusion and two initial transformation parameters (under computer-aided guidance). Coregistration is accomplished (converges) in approximately 8 min for a 128 x 128 x 128 set of 2 mm{sup 3} voxels. The complete process (editing, reslicing, normalization, coregistration) takes about 20 min. We have also developed automated 3-dimensional parametric images ({open_quotes}t{close_quotes}, {open_quotes}z{close_quotes}, and subtraction images) from coregistered data sets for statistical analyses. Data are compared against a coregistered normal control group (N = 50) distributed in age and gender for matching against subject samples.

  1. Filters in 2D and 3D Cardiac SPECT Image Processing

    PubMed Central

    Ploussi, Agapi; Synefia, Stella

    2014-01-01

    Nuclear cardiac imaging is a noninvasive, sensitive method providing information on cardiac structure and physiology. Single photon emission tomography (SPECT) evaluates myocardial perfusion, viability, and function and is widely used in clinical routine. The quality of the tomographic image is a key for accurate diagnosis. Image filtering, a mathematical processing, compensates for loss of detail in an image while reducing image noise, and it can improve the image resolution and limit the degradation of the image. SPECT images are then reconstructed, either by filter back projection (FBP) analytical technique or iteratively, by algebraic methods. The aim of this study is to review filters in cardiac 2D, 3D, and 4D SPECT applications and how these affect the image quality mirroring the diagnostic accuracy of SPECT images. Several filters, including the Hanning, Butterworth, and Parzen filters, were evaluated in combination with the two reconstruction methods as well as with a specified MatLab program. Results showed that for both 3D and 4D cardiac SPECT the Butterworth filter, for different critical frequencies and orders, produced the best results. Between the two reconstruction methods, the iterative one might be more appropriate for cardiac SPECT, since it improves lesion detectability due to the significant improvement of image contrast. PMID:24804144

  2. Filters in 2D and 3D Cardiac SPECT Image Processing.

    PubMed

    Lyra, Maria; Ploussi, Agapi; Rouchota, Maritina; Synefia, Stella

    2014-01-01

    Nuclear cardiac imaging is a noninvasive, sensitive method providing information on cardiac structure and physiology. Single photon emission tomography (SPECT) evaluates myocardial perfusion, viability, and function and is widely used in clinical routine. The quality of the tomographic image is a key for accurate diagnosis. Image filtering, a mathematical processing, compensates for loss of detail in an image while reducing image noise, and it can improve the image resolution and limit the degradation of the image. SPECT images are then reconstructed, either by filter back projection (FBP) analytical technique or iteratively, by algebraic methods. The aim of this study is to review filters in cardiac 2D, 3D, and 4D SPECT applications and how these affect the image quality mirroring the diagnostic accuracy of SPECT images. Several filters, including the Hanning, Butterworth, and Parzen filters, were evaluated in combination with the two reconstruction methods as well as with a specified MatLab program. Results showed that for both 3D and 4D cardiac SPECT the Butterworth filter, for different critical frequencies and orders, produced the best results. Between the two reconstruction methods, the iterative one might be more appropriate for cardiac SPECT, since it improves lesion detectability due to the significant improvement of image contrast.

  3. Development of an MR-compatible SPECT system (MRSPECT) for simultaneous data acquisition.

    PubMed

    Hamamura, Mark J; Ha, Seunghoon; Roeck, Werner W; Muftuler, L Tugan; Wagenaar, Douglas J; Meier, Dirk; Patt, Bradley E; Nalcioglu, Orhan

    2010-03-21

    In medical imaging, single-photon emission computed tomography (SPECT) can provide specific functional information while magnetic resonance imaging (MRI) can provide high spatial resolution anatomical information as well as complementary functional information. In this study, we developed a miniaturized dual-modality SPECT/MRI (MRSPECT) system and demonstrated the feasibility of simultaneous SPECT and MRI data acquisition, with the possibility of whole-body MRSPECT systems through suitable scaling of components. For our MRSPECT system, a cadmium-zinc-telluride (CZT) nuclear radiation detector was interfaced with a specialized radiofrequency (RF) coil and placed within a whole-body 4 T MRI system. Various phantom experiments characterized the interaction between the SPECT and MRI hardware components. The metallic components of the SPECT hardware altered the B(0) field and generated a non-uniform reduction in the signal-to-noise ratio (SNR) of the MR images. The presence of a magnetic field generated a position shift and resolution loss in the nuclear projection data. Various techniques were proposed to compensate for these adverse effects. Overall, our results demonstrate that accurate, simultaneous SPECT and MRI data acquisition is feasible, justifying the further development of MRSPECT for either small-animal imaging or whole-body human systems by using appropriate components.

  4. SPECT attenuation correction: an essential tool to realize nuclear cardiology's manifest destiny.

    PubMed

    Garcia, Ernest V

    2007-01-01

    Single photon emission computed tomography (SPECT) myocardial perfusion imaging has attained widespread clinical acceptance as a standard of care for cardiac patients. Yet, physical phenomena degrade the accuracy of how our cardiac images are visually interpreted or quantitatively analyzed. This degradation results in cardiac images in which brightness or counts are not necessarily linear with tracer uptake or myocardial perfusion. Attenuation correction (AC) is a methodology that has evolved over the last 30 years to compensate for this degradation. Numerous AC clinical trials over the last 10 years have shown increased diagnostic accuracy over non-AC SPECT for detecting and localizing coronary artery disease, particularly for significantly increasing specificity and normalcy rate. This overwhelming evidence has prompted our professional societies to issue a joint position statement in 2004 recommending the use of AC to maximize SPECT diagnostic accuracy and clinical usefulness. Phantom and animal studies have convincingly shown how SPECT AC recovers the true regional myocardial activity concentration, while non-AC SPECT does not. Thus, AC is also an essential tool for extracting quantitative parameters from all types of cardiac radionuclide distributions, and plays an important role in establishing cardiac SPECT for flow, metabolic, innervation, and molecular imaging, our manifest destiny.

  5. Final Report: A CdZnTe detector for MRI-compatible SPECT Systems

    SciTech Connect

    Meng, Ling-Jian

    2012-12-27

    The key objective of this project is to develop the enabling technology for future MRI-compatible nuclear (e.g. SPECT) imaging system, and to demonstrate the feasibility of performing simultaneous MR and SPECT imaging studies of the same object. During the past three years, we have developed (a) a MRI-compatible ultrahigh resolution gamma ray detector and associated readout electronics, (b) a theoretical approach for modeling the effect of strong magnetic field on SPECT image quality, and (c) a maximum-likelihood (ML) based reconstruction routine with correction for the MR-induced distortion. With this support, we have also constructed a four-head MR-compatible SPECT system and tested the system inside a 3-T clinical MR-scanner located on UI campus. The experimental results obtained with this system have clearly demonstrated that sub-500um spatial resolution can be achieved with a SPECT system operated inside a 3-T MRI scanner. During the past three years, we have accomplished most of the major objectives outlined in the original proposal. These research efforts have laid out a solid foundation the development of future MR-compatible SPECT systems for both pre-clinical and clinical imaging applications.

  6. Proceedings of the cardiac PET summit meeting 12 may 2014: Cardiac PET and SPECT instrumentation.

    PubMed

    Garcia, Ernest V

    2015-06-01

    Advances in PET and SPECT and imaging hardware and software are vastly improving the noninvasive evaluation of myocardial perfusion and function. PET perfusion imaging has benefitted from the introduction of novel detectors that now allow true 3D imaging, and precise attenuation correction (AC). These developments have also resulted in perfusion images with higher spatial and contrast resolution that may be acquired in shorter protocols and/or with less patient radiation exposure than traditional PET or SPECT studies. Hybrid PET/CT cameras utilize transmission computed tomographic (CT) scans for AC, and offer the additional clinical advantages of evaluating coronary calcium and myocardial anatomy but at a higher cost than PET scanners that use (68)Ge radioactive line sources. As cardiac PET systems continue to improve, dedicated cardiac SPECT systems are also undergoing a profound change in their design. The scintillation camera general purpose design is being replaced with systems with multiple detectors focused on the heart yielding 5 to 10 times the sensitivity of conventional SPECT. As a result, shorter acquisition times and/or lower tracer doses produce higher quality SPECT images than were possible before. This article reviews these concepts and compares the attributes of PET and SPECT instrumentation.

  7. Hybrid SPECT/CT Imaging in the Evaluation of Coronary Stenosis: Role in Diabetic Patients

    PubMed Central

    Romagnoli, Andrea; Schillaci, Orazio; Arganini, Chiara; Gaspari, Eleonora; Ricci, Aurora; Morosetti, Daniele; Coco, Irene; Crusco, Sonia; Calabria, Ferdinando; Sperandio, Massimiliano; Simonetti, Giovanni

    2013-01-01

    Purpose. Our purpose was to combine the results of the MDCT (multidetector computed tomography) morphological data and the SPECT (single-photon emission computed tomography) data using hybrid imaging to overcome the limits of the MDCT in the evaluation of coronary stenosis in diabetic patients with large amount of calcium in the coronary arteries. Method and Materials. 120 diabetic patients underwent MDCT examination and SPECT examination. We evaluated 324 coronary arteries. After the examinations, we merged CT and SPECT images. Results. CT evaluation: 52 (32.8%) coronaries with stenosis ≥ 50%, 228 (70.4%) with stenosis < 50%, and 44 (13.6%) with a doubtful evaluation. SPECT evaluation: 80 (24.7%) areas with hypoperfusion, 232 (71.6%) with normal perfusion, and 12 (3.7%) with a doubtful evaluation. Of 324 coronary arteries and corresponding areas, the hybrid SPECT/CT evaluation showed 92 (28.4%) areas with hypoperfusion, and 232 (71.6%) with normal perfusion. Conclusion. Hybrid CT/SPECT imaging could be useful in the detection of significant coronary stenosis in patients with large amount of coronary calcifications. PMID:24959556

  8. Early rocket observations of auroral bremsstrahlung and its absorption in the mesosphere

    NASA Astrophysics Data System (ADS)

    Van Allen, James A.

    1995-08-01

    In the summer and autumn of 1957 the author and his colleagues at the University of Iowa conducted 10 successful balloon-launched rocket (rockoon) flights of Geiger-Mueller tubes during two shipboard expeditions, one to the arctic and the other to the antarctic. Summit altitudes ranged from 77 to 130 km. One flight was conducted in the equatorial zone, six in the northern auroral zone, and three in the southern auroral zone. Detailed results of each flight are presented. Auroral bremsstrahlung was detected on eight of the nine high-latitude flights. By virtue of physical shielding, the detectors were insensitive to photons of energy E<8 keV. Hence our derived absolute spectra refer to the high-energy tail of the auroral electron spectrum and the resulting bremmstrahlung. For the energy range E>8 keV, we find a typical e-folding energy E* of about 10 keV for a differential photon number spectrum of the form dn/dE=Aexp(-E/E*) with A in units of photons (cm2 s keV)-1. Essentially, the same value of E* is obtained by two complementary methods: (1) The dependence of counting rate on atmospheric depth Q and (2) the inverse ratio of counting rates of an ``unshielded'' tube and one with an added shield. A detailed discussion of the bases for interpretation of the flight data is given in an extended appendix. For a representative set of data (flight 64) we find an omnidirectional flux of downward moving photons of 2.4×104(cm2s)-1 at Q=0, the integral of the above spectrum from E=0 to E=∞ with the explicit understanding that this result does not include the presumably much greater flux of photons having E<8 keV and a much steeper spectrum. The corresponding electron number flux striking the top of the atmosphere is 9.3×107 electrons (cm2s)-1 with an e-folding energy T*=30 keV. The corresponding energy flux is 4.5 erg (cm2s)-1. Both of the two latter fluxes represent the integral from electron energy T=0 to T=∞ of the high-energy tail of the electron spectrum, again

  9. Constraints on Cosmological Parameters From The Sunyaev-Zel'dovich Effect and Thermal Bremsstrahlung

    NASA Technical Reports Server (NTRS)

    Molnar, S. M.; Mushotzky, R. F.; White, Nicholas E. (Technical Monitor)

    2000-01-01

    We discuss the possibility of constraining cosmological parameters using the Sunyaev-Zel'dovich (SZ) effect and thermal bremsstrahlung caused by intra-cluster gas in clusters of galaxies. The new generation of X-ray satellites and ground based interferometers dedicated to SZ observations will enable one to reduce uncertainties in these measurements, and thus make this method potentially quite promising in the near future. The importance of this method is that, unlike most other methods, it is based on physical principles, no 'standard candles' or 'rulers' needed. We estimate the accuracy achievable in the determination of the matter density, OMEGA(sub m), the cosmological constant, OMEGA(sub LAMBDA), and the Hubble constant, h, using the redshift dependence of the angular diameter distance derived from observations in the near future. We demonstrate that constraints from the angular diameter distance are orthogonal to those from Cosmic Microwave Background (CMB) fluctuations in the parameter space defined by OMEGA(sub m), OMEGA(sub LAMBDA), and h. Assuming a statistical error of five percent in the angular diameter distance for each cluster in a sample of five hundred clusters, we show that the redshift dependence of the angular diameter distance combined with constraints from CMB fluctuations can put stringent constraints on OMEGA(sub m) (+/- 0.03), OMEGA(sub LAMBDA) (+/- 0.03) and h (+/- 0.03, 3(sigma) errors). We also show that, with as few as 50 clusters between redshifts 0.01 and 1.5 with an assumed 10% statistical error in the angular diameter distance determination, one can distinguish between models with zero cosmological constant and spatially flat models with a cosmological constant with high confidence level (independently from the supernova results) and put meaningful constraints on OMEGA(sub m) (+/- 0.01), OMEGA(sub LAMBDA) (+/- 0.01) and h (+/- 0.01, 3(sigma) errors). With the expected advances in observational technology, we will be limited by

  10. Effect of reconstruction algorithms on the accuracy of 99mTc sestamibi SPECT/CT parathyroid imaging

    PubMed Central

    Nichols, Kenneth J; Tronco, Gene G; Palestro, Christopher J

    2015-01-01

    The superiority of SPECT/CT over SPECT for 99mTc-sestamibi parathyroid imaging often is assumed to be due to improved lesion localization provided by the anatomic component (computed tomography) of the examination. It also is possible that this superiority may be related to the algorithms used for SPECT data reconstruction. The objective of this investigation was to determine the effect of SPECT reconstruction algorithms on the accuracy of MIBI SPECT/CT parathyroid imaging. We retrospectively analyzed preoperative MIBI SPECT/CT parathyroid imaging studies performed on 106 patients. SPECT data were reconstructed by filtered back projection (FBP) and by iterative reconstruction with corrections for collimator resolution recovery and attenuation (IRC). Two experienced readers independently graded lesion detection certainty on a 5-point scale without knowledge of each other’s readings, reconstruction methods, other test results or final diagnoses. All patients had surgical confirmation of the final diagnosis, including disease limited to the neck, and location and weight of excised lesion(s). There were 135 parathyroid lesions among the 106 patients. For FBP SPECT/CT and IRC SPECT/CT sensitivity was 76% and 90% (p = 0.003), specificity was 87% and 87% (p = 0.90), and accuracy was 83% and 88% (p = 0.04), respectively. Inter-rater agreement was significantly higher for IRC than for FBP (kappa = 0.76, “good agreement”, versus kappa = 0.58, “moderate agreement”, p < 0.0001). We conclude that the improved accuracy of MIBI SPECT/CT compared to MIBI SPECT for preoperative parathyroid lesion localization is due in part to the use of IRC for SPECT data reconstruction. PMID:25973340

  11. Study of silver K{alpha} and bremsstrahlung radiation from short-pulse laser-matter interactions with applications for x-ray radiography

    SciTech Connect

    Westover, B.; Beg, F. N.; MacPhee, A.; Chen, C.; Hey, D.; Maddox, B.; Park, H.-S.; Remington, B.; Ma, T.

    2010-08-15

    Measurements of K{alpha} radiation yield and x-ray bremsstrahlung emission from thin-foil silver targets are presented. The targets were irradiated by a short pulse laser with intensities from 5x10{sup 16} to 10{sup 18} W/cm{sup 2} at 40 ps. Single hit charge-coupled device detectors, differential filter-stack detectors, and a crystal spectrometer were used to investigate the angular distribution of the K{alpha} and bremsstrahlung x-rays. This study is the first to use a broadband detector to estimate the absolute numbers of K{alpha} photons and to determine K{alpha} to bremsstrahlung ratios. The relevance of this work in the context of x-ray diffraction and x-ray radiography is discussed.

  12. Studies on the effect of the axial magnetic field on the x-ray bremsstrahlung in a 2.45 GHz permanent magnet microwave ion source

    SciTech Connect

    Kumar, Narender; Rodrigues, G. Lakshmy, P. S.; Mathur, Y.; Ahuja, R.; Kanjilal, D.; Baskaran, R.

    2014-02-15

    A compact microwave ion source has been designed and developed for operation at a frequency of 2.45 GHz. The axial magnetic field is based on two permanent magnet rings, operating in the “off-resonance” mode and is tunable by moving the permanent magnets. In order to understand the electron energy distribution function, x-ray bremsstrahlung has been measured in the axial direction. Simulation studies on the x-ray bremsstrahlung have been carried out to compare with the experimental results. The effect of the axial magnetic field with respect to the microwave launching position and the position of the extraction electrode on the x-ray bremsstrahlung have been studied.

  13. Evaluation using m.c.n.p. code of the bremsstrahlung energy spectrum produced by interactions between structural materials and accelerated electrons

    NASA Astrophysics Data System (ADS)

    Calderaro, Elio

    2004-09-01

    In order to design the biological shield of industrial accelerator plants, it is needed to have a good knowledge of the bremsstrahlung energy spectrum and the intensity of the bremsstrahlung produced by electron interactions with both products (usually water equivalent) and structural materials such as concrete, iron, aluminium. Using the MCNP code, a normalized bremsstrahlung energy spectrum was obtained for materials with average atomic number lower than or equal to 13 and irradiated with 5 and 10 Mev electrons, respectively; multiplying the spectrum by suitable coefficients, it was possible to obtain the real spectrum for materials such as water, concrete, aluminium and iron. The MCNP results have been obtained with relative error less than 2%.

  14. Multi-pinhole collimator design for small-object imaging with SiliSPECT: a high-resolution SPECT

    PubMed Central

    Shokouhi, S; Metzler, S D; Wilson, D W; Peterson, T E

    2010-01-01

    We have designed a multi-pinhole collimator for a dual-headed, stationary SPECT system that incorporates high-resolution silicon double-sided strip detectors. The compact camera design of our system enables imaging at source–collimator distances between 20 and 30 mm. Our analytical calculations show that using knife-edge pinholes with small-opening angles or cylindrically shaped pinholes in a focused, multi-pinhole configuration in combination with this camera geometry can generate narrow sensitivity profiles across the field of view that can be useful for imaging small objects at high sensitivity and resolution. The current prototype system uses two collimators each containing 127 cylindrically shaped pinholes that are focused toward a target volume. Our goal is imaging objects such as a mouse brain, which could find potential applications in molecular imaging. PMID:19088387

  15. Initial experience with SPECT imaging of the brain using I-123 p-iodoamphetamine in focal epilepsy

    SciTech Connect

    LaManna, M.M.; Sussman, N.M.; Harner, R.N.; Kaplan, L.R.; Hershey, B.L.; Bernstein, D.R.; Goldstein, P.; Parker, J.A.; Wolodzko, J.G.; Popky, G.L.

    1989-06-01

    Nineteen patients with complex partial seizures refractory to medical treatment were examined with routine electroencephalography (EEG), video EEG monitoring, computed tomography or magnetic resonance imaging, neuropsychological tests and interictal single photon emission computed tomography (SPECT) with I-123 iodoamphetamine (INT). In 18 patients, SPECT identified areas of focal reduction in tracer uptake that correlated with the epileptogenic focus identified on the EEG. In addition, SPECT disclosed other areas of neurologic dysfunction as elicited on neuropsychological tests. Thus, IMP SPECT is a useful tool for localizing epileptogenic foci and their associated dynamic deficits.

  16. Dose calculations using MARS for Bremsstrahlung beam stops and collimators in APS beamline stations.

    SciTech Connect

    Dooling, J.; Accelerator Systems Division

    2010-11-01

    The Monte Carlo radiation transport code MARS is used to model the generation of gas bremsstrahlung (GB) radiation from 7-GeV electrons which scatter from residual gas atoms in undulator straight sections within the Advanced Photon Source (APS) storage ring. Additionally, MARS is employed to model the interactions of the GB radiation with components along the x-ray beamlines and then determine the expected radiation dose-rates that result. In this manner, MARS can be used to assess the adequacy of existing shielding or the specifications for new shielding when required. The GB radiation generated in the 'thin-target' of an ID straight section will consist only of photons in a 1/E-distribution up to the full energy of the stored electron beam. Using this analytical model, the predicted GB power for a typical APS 15.38-m insertion device (ID) straight section is 4.59 x 10{sup -7} W/nTorr/mA, assuming a background gas composed of air (Z{sub eff} = 7.31) at room temperature (293K). The total GB power provides a useful benchmark for comparisons between analytical and numerical approaches. We find good agreement between MARS and analytical estimates for total GB power. The extended straight section 'target' creates a radial profile of GB, which is highly peaked centered on the electron beam. The GB distribution reflects the size of the electron beam that creates the radiation. Optimizing the performance of MARS in terms of CPU time per incident trajectory requires the use of a relatively short, high-density gas target (air); in this report, the target density is {rho}L = 2.89 x 10{sup -2} g/cm{sup 2} over a length of 24 cm. MARS results are compared with the contact dose levels reported in TB-20, which used EGS4 for radiation transport simulations. Maximum dose-rates in 1 cc of tissue phantom form the initial basis for comparison. MARS and EGS4 results are approximately the same for maximum 1-cc dose-rates and attenuation in the photon-dominated regions; for thicker

  17. Bremsstrahlung and K(alpha) fluorescence measurements for inferring conversion efficiencies into fast ignition relevant hot electrons

    SciTech Connect

    Chen, C D; Patel, P K; Hey, D S; Mackinnon, A J; Key, M H; Akli, K U; Bartal, T; Beg, F N; Chawla, S; Chen, H; Freeman, R R; Higginson, D P; Link, A; Ma, T Y; MacPhee, A G; Stephens, R B; Van Woerkom, L D; Westover, B; Porkolab, M

    2009-07-24

    The Bremsstrahlung and K-shell emission from 1 mm x 1 mm x 1 mm planar targets irradiated by a short-pulse 3 x 10{sup 18}-8 x 10{sup 19} W/cm{sup 2} laser were measured. The Bremsstrahlung was measured using a filter stack spectrometer with spectral discrimination up to 500 keV. K-shell emission was measured using a single photon counting charge coupled device (CCD). From Monte Carlo modeling of the target emission, conversion efficiencies into 1-3 MeV electrons of 3-12%, representing 20-40% total conversion efficiencies were inferred for intensities up to 8 x 10{sup 19} W/cm{sup 2}. Comparisons to scaling laws using synthetic energy spectra generated from the intensity distribution of the focal spot imply slope temperatures less than the ponderomotive potential of the laser. Resistive transport effects may result in potentials of a few hundred kV in the first few tens of microns in the target. This would lead to higher total conversion efficiencies than inferred from Monte Carlo modeling but lower conversion efficiencies into 1-3 MeV electrons.

  18. Study of photo-proton reactions driven by bremsstrahlung radiation of high-intensity laser generated electrons

    NASA Astrophysics Data System (ADS)

    Spohr, K. M.; Shaw, M.; Galster, W.; Ledingham, K. W. D.; Robson, L.; Yang, J. M.; McKenna, P.; McCanny, T.; Melone, J. J.; Amthor, K.-U.; Ewald, F.; Liesfeld, B.; Schwoerer, H.; Sauerbrey, R.

    2008-04-01

    Photo-nuclear reactions were investigated using a high power table-top laser. The laser system at the University of Jena (I ~ 3-5×1019 W cm-2) produced hard bremsstrahlung photons (kT~2.9 MeV) via a laser-gas interaction which served to induce (γ, p) and (γ, n) reactions in Mg, Ti, Zn and Mo isotopes. Several (γ, p) decay channels were identified using nuclear activation analysis to determine their integral reaction yields. As the laser-generated bremsstrahlung spectra stretches over the energy regime dominated by the giant dipole resonance (GDR), these yield measurements were used in conjunction with theoretical estimates of the resonance energies Eres and their widths Γres to derive the integral reaction cross-section σint(γ,p) for 25Mn, 48, 49Ti, 68Zn and 97, 98Mo isotopes for the first time. This study enabled the determination of the previously unknown \\frac{{\\sigma}^int(\\gamma,n)}{{\\sigma}^int(\\gamma,p)} cross-section ratios for these isotopes. The experiments were supported by extensive model calculations (Empire) and the results were compared to the Thomas-Reiche-Kuhn (TRK) dipole sum rule as well as to the experimental data in neighboring isotopes and good agreement was observed. The Coulomb barrier and the neutron excess strongly influence the \\frac{{\\sigma}^int(\\gamma,n)}{{\\sigma}^int(\\gamma,p)} ratios for increasing target proton and neutron numbers.

  19. Qualitative comparison of bremsstrahlung X-rays and 800 MeV protons for tomography of urania fuel pellets

    DOE PAGES

    Morris, Christopher L.; Bourke, Mark A.; Byler, Darrin D.; ...

    2013-02-11

    We present an assessment of x-rays and proton tomography as tools for studying the time dependence of the development of damage in fuel rods. Also, we show data taken with existing facilities at Los Alamos National Laboratory that support this assessment. Data on surrogate fuel rods has been taken using the 800 MeV proton radiography (pRad) facility at the Los Alamos Neutron Science Center (LANSCE), and with a 450 keV bremsstrahlung X-ray tomography facility. The proton radiography pRad facility at LANSCE can provide good position resolution (<70 μm has been demonstrate, 20 μm seems feasible with minor changes) for tomographymore » on activated fuel rods. Bremsstrahlung x-rays may be able to provide better than 100 μm resolution but further development of sources, collimation and detectors is necessary for x-rays to deal with the background radiation for tomography of activated fuel rods.« less

  20. Bremsstrahlung in the scattering of low-energy electrons by neutral atomic systems. [in atmosphere of sun and cool stars

    NASA Technical Reports Server (NTRS)

    Gould, R. J.

    1985-01-01

    By elementary methods, the cross section for electron-atom and electron-molecule bremsstrahlung is computed in the limit when the incident electron energy is much less than Ry. The procedure employs the classical soft-photon emission probability formula for general (h/2pi)(omega), yielding a simple expression for the bremsstrahlung cross section in terms of the total elastic scattering cross section. The validity of the method is discussed, and results are compared with more elaborate and accurate calculations. Comparison is made with ('free-free') opacity calculations for the associated process at the temperature (6300 K) of the solar atmosphere. For chi sub omega = (h/2pi)(omega)/kT = 1, the computed absorption coefficient is within 2, 7, and 12 percent of accurate calculations for scatterings by H, He, and H2, respectively. The general dependence of the opacity on chi sub omega is described well by the simple formula, although the error is larger for higher chi sub omega; it is suggested that the inaccuracy at high frequencies is due to the failure of the soft-photon approximation.

  1. Thick target bremsstrahlung spectra for 1.00-, 1.25-, and 1.40-Mev electrons

    USGS Publications Warehouse

    Miller, W.; Motz, J.W.; Cialella, C.

    1954-01-01

    The spectrum of radiation produced by 1.0-, 1.25-, and 1.40-Mev electrons incident on a thick tungsten target was measured at 0A????and 90A????with the incident beam by a method involving the magnetic analysis of Compton electrons. The effects of electron scattering and energy loss in the target preclude any simple interpretation of this data to yield a differential bremsstrahlung cross section. However, an estimate of the spectra to be expected at 0A????and 90A????was obtained by combining the Sauter expression for the bremsstrahlung cross section with the available information on electron scatter and energy loss in the target and backscatter from the target. The reliability of the estimate is limited because the Sauter formula was calculated by using the Born approximation, the electron scattering calculations are applicable to an infinite medium only, and the backscatter was estimated empirically from Bothe's experimental data which were obtained with lower energy electrons (370 kev). Furthermore electron energy straggling was neglected. Nevertheless, the predicted spectral shapes at 0A????and 90A????and the relative intensities at these two angles are in qualitative agreement with the measured values. The absolute magnitudes of the measured intensities at both angles are about a factor of two greater than the predicted values. ?? 1954 The American Physical Society.

  2. Effect of frequency tuning on bremsstrahlung spectra, beam intensity, and shape in the 10 GHz NANOGAN electron cyclotron resonance ion source

    SciTech Connect

    Rodrigues, G. Mal, Kedar; Kumar, Narender; Lakshmy, P. S.; Mathur, Y.; Kumar, P.; Kanjilal, D.; Roy, A.; Baskaran, R.

    2014-02-15

    Studies on the effect of the frequency tuning on the bremsstrahlung spectra, beam intensities, and beam shape of various ions have been carried out in the 10 GHz NANOGAN ECR ion source. The warm and cold components of the electrons were found to be directly correlated with beam intensity enhancement in case of Ar{sup 9+} but not so for O{sup 5+}. The warm electron component was, however, much smaller compared to the cold component. The effect of the fine tuning of the frequency on the bremsstrahlung spectrum, beam intensities and beam shape is presented.

  3. Technological value of SPECT/CT fusion imaging for the diagnosis of lower gastrointestinal bleeding.

    PubMed

    Wang, Z G; Zhang, G X; Hao, S H; Zhang, W W; Zhang, T; Zhang, Z P; Wu, R X

    2015-11-24

    The aim of this study was to assess the clinical value of diagnosing and locating lower gastrointestinal (GI) bleeding using single photon emission computed tomography (SPECT)/computed tomography (CT) fusion imaging with 99mTc labeled red blood cells ((99m)Tc-RBC). Fifty-six patients with suspected lower GI bleeding received a preoperative intravenous injection of (99m)Tc-RBC and each underwent planar, SPECT/CT imaging of the lower abdominal region. The location and path of lower GI bleeding were diagnosed by contrastive analysis of planar and SPECT/CT fusion imaging. Among the 56 patients selected, there were abnormalities in concentrated radionuclide activity with planar imaging in 50 patients and in SPECT/CT fusion imaging in 52 patients. Moreover, bleeding points that were coincident with the surgical results were evident with planar imaging in 31 patients and with SPECT/CT fusion imaging in 48 patients. The diagnostic sensitivity of planar imaging and SPECT/CT fusion imaging were 89.3% (50/56) and 92.9% (52/56), respectively, and the difference was not statistically significant (χ(2) = 0.11, P > 0.05). The corresponding positional accuracy values were 73.8% (31/42) and 92.3% (48/52), and the difference was statistically significant (χ(2) = 4.63, P < 0.05). (99m)Tc- RBC SPECT/CT fusion imaging is an effective, simple, and accurate method that can be used for diagnosing and locating lower GI bleeding.

  4. Invisible Base Electrode Coordinates Approximation for Simultaneous SPECT and EEG Data Visualization

    NASA Astrophysics Data System (ADS)

    Kowalczyk, L.; Goszczynska, H.; Zalewska, E.; Bajera, A.; Krolicki, L.

    2014-04-01

    This work was performed as part of a larger research concerning the feasibility of improving the localization of epileptic foci, as compared to the standard SPECT examination, by applying the technique of EEG mapping. The presented study extends our previous work on the development of a method for superposition of SPECT images and EEG 3D maps when these two examinations are performed simultaneously. Due to the lack of anatomical data in SPECT images it is a much more difficult task than in the case of MRI/EEG study where electrodes are visible in morphological images. Using the appropriate dose of radioisotope we mark five base electrodes to make them visible in the SPECT image and then approximate the coordinates of the remaining electrodes using properties of the 10-20 electrode placement system and the proposed nine-ellipses model. This allows computing a sequence of 3D EEG maps spanning on all electrodes. It happens, however, that not all five base electrodes can be reliably identified in SPECT data. The aim of the current study was to develop a method for determining the coordinates of base electrode(s) missing in the SPECT image. The algorithm for coordinates approximation has been developed and was tested on data collected for three subjects with all visible electrodes. To increase the accuracy of the approximation we used head surface models. Freely available model from Oostenveld research based on data from SPM package and our own model based on data from our EEG/SPECT studies were used. For data collected in four cases with one electrode not visible we compared the invisible base electrode coordinates approximation for Oostenveld and our models. The results vary depending on the missing electrode placement, but application of the realistic head model significantly increases the accuracy of the approximation.

  5. Radiation dose estimate in small animal SPECT and PET.

    PubMed

    Funk, Tobias; Sun, Mingshan; Hasegawa, Bruce H

    2004-09-01

    Calculations of radiation dose are important in assessing the medical and biological implications of ionizing radiation in medical imaging techniques such as SPECT and PET. In contrast, radiation dose estimates of SPECT and PET imaging of small animals are not very well established. For that reason we have estimated the whole-body radiation dose to mice and rats for isotopes such as 18F, 99mTc, 201Tl, (111)In, 123I, and 125I that are used commonly for small animal imaging. We have approximated mouse and rat bodies with uniform soft tissue equivalent ellipsoids. The mouse and rat sized ellipsoids had a mass of 30 g and 300 g, respectively, and a ratio of the principal axes of 1:1:4 and 0.7:1:4. The absorbed fractions for various photon energies have been calculated using the Monte Carlo software package MCNP. Using these values, we then calculated MIRD S-values for two geometries that model the distribution of activity in the animal body: (a) a central point source and (b) a homogeneously distributed source, and compared these values against S-value calculations for small ellipsoids tabulated in MIRD Pamphlet 8 to validate our results. Finally we calculated the radiation dose taking into account the biological half-life of the radiopharmaceuticals and the amount of activity administered. Our calculations produced S-values between 1.06 x 10(-13) Gy/Bq s and 2.77 x 10(-13) Gy/Bq s for SPECT agents, and 15.0 x 10(-13) Gy/Bq s for the PET agent 18F, assuming mouse sized ellipsoids with uniform source distribution. The S-values for a central point source in an ellipsoid are about 10% higher than the values obtained for the uniform source distribution. Furthermore, the S-values for mouse sized ellipsoids are approximately 10 times higher than for the rat sized ellipsoids reflecting the difference in mass. We reviewed published data to obtain administered radioactivity and residence times for small animal imaging. From these values and our computed S-values we estimated

  6. Sci—Thur PM: Imaging — 05: Calibration of a SPECT/CT camera for quantitative SPECT with {sup 99m}Tc

    SciTech Connect

    Gaudin, Émilie; Montégiani, Jean-François; Després, Philippe; Beauregard, Jean-Mathieu

    2014-08-15

    While quantitation is the norm in PET, it is not widely available yet in SPECT. This work's aim was to calibrate a commercially available SPECT/CT system to perform quantitative SPECT. Counting sensitivity, dead-time (DT) constant and partial volume effect (PVE) of the system were assessed. A dual-head Siemens SymbiaT6 SPECT/CT camera equipped with low energy high-resolution collimators was studied. {sup 99m}Tc was the radioisotope of interest because of its wide usage in nuclear medicine. First, point source acquisitions were performed (activity: 30–990MBq). Further acquisitions were then performed with a uniform Jaszczak phantom filled with water at high activity (25–5000MBq). PVE was studied using 6 hot spheres (diameters: 9.9–31.2 mm) filled with {sup 99m}Tc (2.8MBq/cc) in the Jaszczak phantom, which was: (1) empty, (2) water-filled and (3) water-filled with low activity (0.1MBq/cc). The data was reconstructed with the Siemens's Flash3D iterative algorithm with 4 subsets and 8 iterations, attenuation-correction (AC) and scatter-correction (SC). DT modelling was based on the total spectrum counting rate. Sensitivity was assessed using AC-SC reconstructed SPECT data. Sensitivity and DT for the sources were 99.51±1.46cps/MBq and 0.60±0.04µs. For the phantom, sensitivity and DT were 109.9±2.3cps/MBq and 0.62±0.13µs. The recovery-coefficient varied from 5% for the 9.9mm, to 80% for the 31.2mm spheres. With our calibration methods, both sensitivity and DT constant of the SPECT camera had little dependence on the object geometry and attenuation. For small objects of known size, recovery-coefficient can be applied to correct PVE. Clinical quantitative SPECT appears to be possible and has many potential applications.

  7. Patient position alters attenuation effects in multipinhole cardiac SPECT

    SciTech Connect

    Timmins, Rachel; Ruddy, Terrence D.; Wells, R. Glenn

    2015-03-15

    Purpose: Dedicated cardiac cameras offer improved sensitivity over conventional SPECT cameras. Sensitivity gains are obtained by large numbers of detectors and novel collimator arrangements such as an array of multiple pinholes that focus on the heart. Pinholes lead to variable amounts of attenuation as a source is moved within the camera field of view. This study evaluated the effects of this variable attenuation on myocardial SPECT images. Methods: Computer simulations were performed for a set of nine point sources distributed in the left ventricular wall (LV). Sources were placed at the location of the heart in both an anthropomorphic and a water-cylinder computer phantom. Sources were translated in x, y, and z by up to 5 cm from the center. Projections were simulated with and without attenuation and the changes in attenuation were compared. A LV with an inferior wall defect was also simulated in both phantoms over the same range of positions. Real camera data were acquired on a Discovery NM530c camera (GE Healthcare, Haifa, Israel) for five min in list-mode using an anthropomorphic phantom (DataSpectrum, Durham, NC) with 100 MBq of Tc-99m in the LV. Images were taken over the same range of positions as the simulations and were compared based on the summed perfusion score (SPS), defect width, and apparent defect uptake for each position. Results: Point sources in the water phantom showed absolute changes in attenuation of ≤8% over the range of positions and relative changes of ≤5% compared to the apex. In the anthropomorphic computer simulations, absolute change increased to 20%. The changes in relative attenuation caused a change in SPS of <1.5 for the water phantom but up to 4.2 in the anthropomorphic phantom. Changes were larger for axial than for transverse translations. These results were supported by SPS changes of up to six seen in the physical anthropomorphic phantom for axial translations. Defect width was also seen to significantly increase. The

  8. SemiSPECT: A small-animal single-photon emission computed tomography (SPECT) imager based on eight cadmium zinc telluride (CZT) detector arrays

    PubMed Central

    Kim, Hyunki; Furenlid, Lars R.; Crawford, Michael J.; Wilson, Donald W.; Barber, H. Bradford; Peterson, Todd E.; Hunter, William C. J.; Liu, Zhonglin; Woolfenden, James M.; Barrett, Harrison H.

    2008-01-01

    The first full single-photon emission computed tomography (SPECT) imager to exploit eight compact high-intrinsic-resolution cadmium zinc telluride (CZT) detectors, called SemiSPECT, has been completed. Each detector consists of a CZT crystal and a customized application-specific integrated circuit (ASIC). The CZT crystal is a 2.7 cm × 2.7 cm × ~ 0.2 cm slab with a continuous top electrode and a bottom electrode patterned into a 64 × 64 pixel array by photolithography. The ASIC is attached to the bottom of the CZT crystal by indium-bump bonding. A bias voltage of −180 V is applied to the continuous electrode. The eight detectors are arranged in an octagonal lead-shielded ring. Each pinhole in the eight-pinhole aperture placed at the center of the ring is matched to each individual detector array. An object is imaged onto each detector through a pinhole, and each detector is operated independently with list-mode acquisition. The imaging subject can be rotated about a vertical axis to obtain additional angular projections. The performance of SemiSPECT was characterized using 99mTc. When a 0.5 mm diameter pinhole is used, the spatial resolution on each axis is about 1.4 mm as estimated by the Fourier crosstalk matrix, which provides an algorithm-independent average resolution over the field of view. The energy resolution achieved by summing neighboring pixel signals in a 3 × 3 window is about 10% full-width-at-half-maximum of the photopeak. The overall system sensitivity is about 0.5 × 10−4 with the energy window of ±10% from the photopeak. Line-phantom images are presented to visualize the spatial resolution provided by SemiSPECT, and images of bone, myocardium, and human tumor xenografts in mice demonstrate the feasibility of preclinical small-animal studies with SemiSPECT. PMID:16532954

  9. SemiSPECT: a small-animal single-photon emission computed tomography (SPECT) imager based on eight cadmium zinc telluride (CZT) detector arrays.

    PubMed

    Kim, Hyunki; Furenlid, Lars R; Crawford, Michael J; Wilson, Donald W; Barber, H Bradford; Peterson, Todd E; Hunter, William C J; Liu, Zhonglin; Woolfenden, James M; Barrett, Harrison H

    2006-02-01

    The first full single-photon emission computed tomography (SPECT) imager to exploit eight compact high-intrinsic-resolution cadmium zinc telluride (CZT) detectors, called SemiSPECT, has been completed. Each detector consists of a CZT crystal and a customized application-specific integrated circuit (ASIC). The CZT crystal is a 2.7 cm x 2.7 cm x -0.2 cm slab with a continuous top electrode and a bottom electrode patterned into a 64 x 64 pixel array by photolithography. The ASIC is attached to the bottom of the CZT crystal by indium-bump bonding. A bias voltage of -180 V is applied to the continuous electrode. The eight detectors are arranged in an octagonal lead-shielded ring. Each pinhole in the eight-pinhole aperture placed at the center of the ring is matched to each individual detector array. An object is imaged onto each detector through a pinhole, and each detector is operated independently with list-mode acquisition. The imaging subject can be rotated about a vertical axis to obtain additional angular projections. The performance of SemiSPECT was characterized using 99mTc. When a 0.5 mm diameter pinhole is used, the spatial resolution on each axis is about 1.4 mm as estimated by the Fourier crosstalk matrix, which provides an algorithm-independent average resolution over the field of view. The energy resolution achieved by summing neighboring pixel signals in a 3 x 3 window is about 10% full-width-at-half-maximum of the photopeak. The overall system sensitivity is about 0.5 x 10(-4) with the energy window of +/-10% from the photopeak. Line-phantom images are presented to visualize the spatial resolution provided by SemiSPECT, and images of bone, myocardium, and human tumor xenografts in mice demonstrate the feasibility of preclinical small-animal studies with SemiSPECT.

  10. Lung Dose Calculation With SPECT/CT for {sup 90}Yittrium Radioembolization of Liver Cancer

    SciTech Connect

    Yu, Naichang; Srinivas, Shaym M.; DiFilippo, Frank P.; Shrikanthan, Sankaran; Levitin, Abraham; McLennan, Gordon; Spain, James; Xia, Ping; Wilkinson, Allan

    2013-03-01

    Purpose: To propose a new method to estimate lung mean dose (LMD) using technetium-99m labeled macroaggregated albumin ({sup 99m}Tc-MAA) single photon emission CT (SPECT)/CT for {sup 90}Yttrium radioembolization of liver tumors and to compare the LMD estimated using SPECT/CT with clinical estimates of LMD using planar gamma scintigraphy (PS). Methods and Materials: Images of 71 patients who had SPECT/CT and PS images of {sup 99m}Tc-MAA acquired before TheraSphere radioembolization of liver cancer were analyzed retrospectively. LMD was calculated from the PS-based lung shunt assuming a lung mass of 1 kg and 50 Gy per GBq of injected activity shunted to the lung. For the SPECT/CT-based estimate, the LMD was calculated with the activity concentration and lung volume derived from SPECT/CT. The effect of attenuation correction and the patient's breathing on the calculated LMD was studied with the SPECT/CT. With these effects correctly taken into account in a more rigorous fashion, we compared the LMD calculated with SPECT/CT with the LMD calculated with PS. Results: The mean dose to the central region of the lung leads to a more accurate estimate of LMD. Inclusion of the lung region around the diaphragm in the calculation leads to an overestimate of LMD due to the misregistration of the liver activity to the lung from the patient's breathing. LMD calculated based on PS is a poor predictor of the actual LMD. For the subpopulation with large lung shunt, the mean overestimation from the PS method for the lung shunt was 170%. Conclusions: A new method of calculating the LMD for TheraSphere and SIR-Spheres radioembolization of liver cancer based on {sup 99m}Tc-MAA SPECT/CT is presented. The new method provides a more accurate estimate of radiation risk to the lungs. For patients with a large lung shunt calculated from PS, a recalculation of LMD based on SPECT/CT is recommended.

  11. Optimal energy window selection of a CZT-based small-animal SPECT for quantitative accuracy

    NASA Astrophysics Data System (ADS)

    Park, Su-Jin; Yu, A. Ram; Choi, Yun Young; Kim, Kyeong Min; Kim, Hee-Joung

    2015-05-01

    Cadmium zinc telluride (CZT)-based small-animal single-photon emission computed tomography (SPECT) has desirable characteristics such as superior energy resolution, but data acquisition for SPECT imaging has been widely performed with a conventional energy window. The aim of this study was to determine the optimal energy window settings for technetium-99 m (99mTc) and thallium-201 (201Tl), the most commonly used isotopes in SPECT imaging, using CZT-based small-animal SPECT for quantitative accuracy. We experimentally investigated quantitative measurements with respect to primary count rate, contrast-to-noise ratio (CNR), and scatter fraction (SF) within various energy window settings using Triumph X-SPECT. The two ways of energy window settings were considered: an on-peak window and an off-peak window. In the on-peak window setting, energy centers were set on the photopeaks. In the off-peak window setting, the ratios of energy differences between the photopeak from the lower- and higher-threshold varied from 4:6 to 3:7. In addition, the energy-window width for 99mTc varied from 5% to 20%, and that for 201Tl varied from 10% to 30%. The results of this study enabled us to determine the optimal energy windows for each isotope in terms of primary count rate, CNR, and SF. We selected the optimal energy window that increases the primary count rate and CNR while decreasing SF. For 99mTc SPECT imaging, the energy window of 138-145 keV with a 5% width and off-peak ratio of 3:7 was determined to be the optimal energy window. For 201Tl SPECT imaging, the energy window of 64-85 keV with a 30% width and off-peak ratio of 3:7 was selected as the optimal energy window. Our results demonstrated that the proper energy window should be carefully chosen based on quantitative measurements in order to take advantage of desirable characteristics of CZT-based small-animal SPECT. These results provided valuable reference information for the establishment of new protocol for CZT

  12. Myocardial perfusion imaging parameters: IQ-SPECT and conventional SPET system comparison.

    PubMed

    Havel, Martin; Kolacek, Michal; Kaminek, Milan; Dedek, Vladimir; Kraft, Otakar; Sirucek, Pavel

    2014-01-01

    Technological advancement in hardware and software development in myocardial perfusion imaging (MPI) leads to the shortening of acquisition time and reduction of the radiation burden to patients. We compared semiquantitative perfusion results and functional parameters of the left ventricle between new dedicated cardiac system with astigmatic collimators called IQ-SPECT (Siemens Medical Solutions, USA) and conventional single photon emission tomography (SPET) system equipped with standard low energy high resolution collimators. A group of randomly selected 81 patients underwent consecutively the MPI procedure on IQ-SPECT and on conventional SPET systen, both without attenuation correction. The summed scores and the values of the functional parameters of the left ventricle: ejection fraction (EF), end-systolic and end-diastolic volumes (ESV, EDV) received from the automatic analysis software were compared and statistically analyzed. Our results showed that summed scores values were significantly higher for the IQ-SPECT system in comparison to the conventional one. Calculated EF were significantly lower for IQ-SPECT, whereas evaluated left ventricular volumes (LVV) were significantly higher for this system. In conclusion, we recorded significant differences in automatically calculated semiquantitative perfusion and functional parameters when compared uncorrected studies obtained by the IQ-SPECT with the conventional SPET system.

  13. MRI-SPECT image registration using multiple MR pulse sequences to examine osteoarthritis of the knee

    NASA Astrophysics Data System (ADS)

    Lynch, John A.; Peterfy, Charles G.; White, David L.; Hawkins, Randall A.; Genant, Harry K.

    1999-05-01

    We have examined whether automated image registration can be used to combine metabolic information from SPECT knee scans with anatomical information from MRI. Ten patients, at risk of developing OA due to meniscal surgery, were examined. 99mTc methyldiphosphonate SPECT, T2-weighted fast spin echo (FSE) MRI, and T1-weighted, 3D fat-suppressed gradient recalled echo (SPGR) MRI images were obtained. Registration was performed using normalized mutual information. For each patient, FSE data was registered to SPGR data, providing a composite MRI image with each voxel represented by two intensities (ISPGR, IFSE). Modifications to the registration algorithm were made to allow registration of SPECT data (one intensity per voxel) to composite MRI data (2 intensities per voxel). Registration sources was assessed by visual inspection of uptake localization over expected anatomical locations, and the absence of uptake over unlikely sites. Three patients were discarded from SPECT-MRI registration tests since they had metallic artifacts that prevented co-registration of MR data. Registration of SPECT to SPGR or FSE data alone proved unreliable, with less than 50% of attempts succeeding. The modified algorithm, treating co-registered SPGR and FSE data as a two-value-per-voxel image, proved most reliable, allowing registration of all patients with no metallic artifacts on MRI.

  14. First use of mini gamma cameras for intra-operative robotic SPECT reconstruction.

    PubMed

    Matthies, Philipp; Sharma, Kanishka; Okur, Ash; Gardiazabal, José; Vogel, Jakob; Lasserl, Tobias; Navab, Nassir

    2013-01-01

    Different types of nuclear imaging systems have been used in the past, starting with pre-operative gantry-based SPECT systems and gamma cameras for 2D imaging of radioactive distributions. The main applications are concentrated on diagnostic imaging, since traditional SPECT systems and gamma cameras are bulky and heavy. With the development of compact gamma cameras with good resolution and high sensitivity, it is now possible to use them without a fixed imaging gantry. Mounting the camera onto a robot arm solves the weight issue, while also providing a highly repeatable and reliable acquisition platform. In this work we introduce a novel robotic setup performing scans with a mini gamma camera, along with the required calibration steps, and show the first SPECT reconstructions. The results are extremely promising, both in terms of image quality as well as reproducibility. In our experiments, the novel setup outperformed a commercial fhSPECT system, reaching accuracies comparable to state-of-the-art SPECT systems.

  15. Measurement of gallbladder volume and dynamics by combined SPECT and planar scintigraphy.

    PubMed

    Brown, P H; Krishnamurthy, G T; Brar, H S; Gray, L H; Gilbert, S

    1986-06-01

    A new method is described for measurement of gallbladder volume based on three-dimensional single photon emission computed tomography (SPECT). The technique was first validated in a body phantom that used a balloon to represent the gallbladder. The balloon was inflated with a known volume and SPECT volume was calculated by summing the voxels in each transaxial slice above a percentage count threshold. The SPECT and true volume showed a high linear correlation between 15 to 90 ml (r = 0.99). The mean fasting gallbladder volume using a technetium-99m-labelled hepatobiliary agent in nine normal subjects was 26 +/- 2 ml (range 18 to 39 ml). By combining the SPECT measurement with a planar technique, it was also possible to evaluate gallbladder emptying parameters. Following a 3 min infusion of 10 ng kg-1 of cholecystokinin octapeptide (CCK), the mean gallbladder ejection rate was 1.2 +/- 0.2 ml min-1 and the residual volume was 12 +/- 2 ml. SPECT offers a new noninvasive method for accurate measurement of gallbladder volume.

  16. A preclinical SPECT camera with depth-of-interaction compensation using a focused-cut scintillator

    NASA Astrophysics Data System (ADS)

    Alhassen, Fares; Kudrolli, Haris; Singh, Bipin; Kim, Sangtaek; Seo, Youngho; Gould, Robert G.; Nagarkar, Vivek V.

    2011-03-01

    Preclinical SPECT offers a powerful means to understand the molecular pathways of metabolic activity in animals. SPECT cameras using pinhole collimators offer high resolution that is needed for visualizing small structures in laboratory animals. One of the limitations of pinhole geometries is that increased magnification causes some rays to travel through the scintillator detector at steep angles, introducing parallax errors due to variable depth-of-interaction in the scintillator, especially towards the edges of the detector field of view. These parallax errors ultimately limit the resolution of pinhole preclinical SPECT systems, especially for higher energy isotopes that can easily penetrate through millimeters of scintillator material. A pixellated, focused-cut scintillator, with its pixels laser-cut so that they are collinear with incoming rays, can potentially compensate for these parallax errors and thus open up a new regime of sub-mm preclinical SPECT. We have built a 4-pinhole prototype gamma camera for preclinical SPECT imaging, using an EMCCD camera coupled to a 3 mm thick CsI(Tl) scintillator whose pixels are focused towards each 500 μm-diameter pinhole aperture of the four pinholes. The focused-cut scintillator was fabricated using a laser ablation process that allows for cuts with very high aspect ratios. We present preliminary results from our phantom experiments.

  17. Impulsive solar X-ray bursts. 3: Polarization and directivity of bremsstrahlung radiation from a beam of electrons directed toward the photosphere

    NASA Technical Reports Server (NTRS)

    Langer, S. H.; Petrosian, V.

    1976-01-01

    The spectrum, directivity and state of polarization is presented of the bremsstrahlung radiation expected from a beam of high energy electrons spiraling along radial magnetic field lines toward the photosphere. The results are used for calculation of the characteristics of the reflected plus direct flux.

  18. Three modality image registration of brain SPECT/CT and MR images for quantitative analysis of dopamine transporter imaging

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Yuzuho; Takeda, Yuta; Hara, Takeshi; Zhou, Xiangrong; Matsusako, Masaki; Tanaka, Yuki; Hosoya, Kazuhiko; Nihei, Tsutomu; Katafuchi, Tetsuro; Fujita, Hiroshi

    2016-03-01

    Important features in Parkinson's disease (PD) are degenerations and losses of dopamine neurons in corpus striatum. 123I-FP-CIT can visualize activities of the dopamine neurons. The activity radio of background to corpus striatum is used for diagnosis of PD and Dementia with Lewy Bodies (DLB). The specific activity can be observed in the corpus striatum on SPECT images, but the location and the shape of the corpus striatum on SPECT images only are often lost because of the low uptake. In contrast, MR images can visualize the locations of the corpus striatum. The purpose of this study was to realize a quantitative image analysis for the SPECT images by using image registration technique with brain MR images that can determine the region of corpus striatum. In this study, the image fusion technique was used to fuse SPECT and MR images by intervening CT image taken by SPECT/CT. The mutual information (MI) for image registration between CT and MR images was used for the registration. Six SPECT/CT and four MR scans of phantom materials are taken by changing the direction. As the results of the image registrations, 16 of 24 combinations were registered within 1.3mm. By applying the approach to 32 clinical SPECT/CT and MR cases, all of the cases were registered within 0.86mm. In conclusions, our registration method has a potential in superimposing MR images on SPECT images.

  19. Utility of the SPECT Tc-99m labeled RBC blood pool scan in the detection of hepatic hemangiomas

    SciTech Connect

    Guze, B.H.; Hawkins, R.A.

    1989-11-01

    The sensitivity of SPECT imaging of hepatic blood pool activity using Tc-99m labeled RBCs was contrasted with magnetic resonance and CT imaging in 22 cases. SPECT is a noninvasive technique with a high sensitivity for the diagnosis of hepatic hemangiomas. It is helpful for clarifying equivocal magnetic resonance imaging results.

  20. Comparison of planar images and SPECT with bayesean preprocessing for the demonstration of facial anatomy and craniomandibular disorders

    SciTech Connect

    Kircos, L.T.; Ortendahl, D.A.; Hattner, R.S.; Faulkner, D.; Taylor, R.L.

    1984-01-01

    Craniomandiublar disorders involving the facial anatomy may be difficult to demonstrate in planar images. Although bone scanning is generally more sensitive than radiography, facial bone anatomy is complex and focal areas of increased or decreased radiotracer may become obscured by overlapping structures in planar images. Thus SPECT appears ideally suited to examination of the facial skeleton. A series of patients with craniomandibular disorders of unknown origin were imaged using 20 mCi Tc-99m MDP. Planar and SPECT (Siemens 7500 ZLC Orbiter) images were obtained four hours after injection. The SPECT images were reconstructed with a filtered back-projection algorithm. In order to improve image contrast and resolution in SPECT images, the rotation views were pre-processed with a Bayesean deblurring algorithm which has previously been show to offer improved contrast and resolution in planar images. SPECT images using the pre-processed rotation views were obtained and compared to the SPECT images without pre-processing and the planar images. TMJ arthropathy involving either the glenoid fossa or the mandibular condyle, orthopedic changes involving the mandible or maxilla, localized dental pathosis, as well as changes in structures peripheral to the facial skeleton were identified. Bayesean pre-processed SPECT depicted the facial skeleton more clearly as well as providing a more obvious demonstration of the bony changes associated with craniomandibular disorders than either planar images or SPECT without pre-processing.

  1. [Compartment analysis of 123I-IMP brain SPECT].

    PubMed

    Higano, S; Shishido, F; Aizawa, Y; Miura, S; Murakami, M; Inugami, A; Kanno, I; Fujita, H; Uemura, K

    1990-01-01

    To clarify the kinetics of N-isopropyl [123I]p-iodoamphetamine (IMP) in the brain, 2-compartment analysis was applied for brain SPECT with 57-minute dynamic scan in 9 subjects. The model consisted of blood component and brain tissue component. Two transfer rate constants were defined; k1 showed the rate from the blood to the brain tissue, and k2 was that of back diffusion. The late scan was performed 210 minutes after the tracer injection. Suitable k values best fitting to the dynamic data were determined for all regions of interest. Predicted regional cerebral activity at 210 minutes using 57-minute dynamic data was well agreed with measured activity. These showed the kinetics of IMP in the brain was well described by the 2-compartment model. The partition coefficient (k1/k2 ratio) was as large as about 35, and almost constant in the various brain structures including hypoperfused areas. These findings indicated that the initial IMP images reflected the reasonable CBF distribution, which gave relatively reliable CBF values even if using microsphere model.

  2. Complementary acupuncture in Parkinson's disease: a spect study.

    PubMed

    Huang, Yong; Jiang, Xuemei; Zhuo, Ying; Wik, Gustav

    2010-02-01

    We studied cerebral effects of complementary acupuncture in Parkinson's disease using single photon emission computed tomography (SPECT) measures of 99mTc-ECD and 99mTc-TRODAT-4, before and after five weeks of treatment. Ten patients were randomly assigned to receive levodopa alone (controls) or levodopa and complementary scalp electro-acupuncture. Before treatment, no hemispheric regional cerebral blood flow (rCBF) differences were found, whereas striatal dopamine transporter (DAT) activity was lower in the most affected hemisphere. Treatment with levodopa alone did not change rCBF, whereas it increased basal ganglion DAT activity in the most affected hemisphere. Patients who received levodopa and complementary acupuncture had increased rCBF in the frontal lobe, the occipital lobe, the basal ganglion, and the cerebellum in the most affected hemisphere as compared to baseline, but there were no changes in basal ganglia DAT levels. Thus, complementary acupuncture treatment in Parkinson's disease may affect rCBF but not basal ganglion DAT.

  3. SPECT scatter modelling in non-uniform attenuating objects

    NASA Astrophysics Data System (ADS)

    Beekman, Freek J.; den Harder, Johan M.; Viergever, Max A.; van Rijk, Peter P.

    1997-06-01

    SPECT quantitation and image contrast are degraded by photon scatter. Water equivalent depths (WEDs) have been used by several investigators to model scatter responses in non-uniform attenuators. The drawback of this approach is the occurrence of undesired fluctuations in the shape of the scatter responses, as is shown by measurements. An improvement of the WED method is presented, based on the assumption that only a part of the scattering object (the region in the `scatter cone') contributes significantly to the detected scatter events. The remaining part of the object is treated as a uniform medium. The extension of the WED method with extra-conical invariance is evaluated by projection measurements of a phantom with a source. Shapes of scatter responses predicted by the method are found to agree better with the measurements than those predicted by conventional WEDs.

  4. Visual-search observers for SPECT simulations with clinical backgrounds

    NASA Astrophysics Data System (ADS)

    Gifford, Howard C.

    2016-03-01

    The purpose of this work was to test the ability of visual-search (VS) model observers to predict the lesion- detection performance of human observers with hybrid SPECT images. These images consist of clinical back- grounds with simulated abnormalities. The application of existing scanning model observers to hybrid images is complicated by the need for extensive statistical information, whereas VS models based on separate search and analysis processes may operate with reduced knowledge. A localization ROC (LROC) study involved the detection and localization of solitary pulmonary nodules in Tc-99m lung images. The study was aimed at op- timizing the number of iterations and the postfiltering of four rescaled block-iterative reconstruction strategies. These strategies implemented different combinations of attenuation correction, scatter correction, and detector resolution correction. For a VS observer in this study, the search and analysis processes were guided by a single set of base morphological features derived from knowledge of the lesion profile. One base set used difference-of- Gaussian channels while a second base set implemented spatial derivatives in combination with the Burgess eye filter. A feature-adaptive VS observer selected features of interest for a given image set on the basis of training-set performance. A comparison of the feature-adaptive observer results against previously acquired human-observer data is presented.

  5. [Dependence of uniformity on the radionuclide in SPECT: test methods].

    PubMed

    Kalnischke, Heiko; Grebe, Gerhard; Zander, Andreas; Munz, Dieter Ludwig; Geworski, Lilli

    2004-01-01

    The aim of this study was to investigate test methods to clarify whether the non-uniformity of a gamma camera depends on individual radionuclides, and whether it is necessary to measure a separate correction matrix for each radionuclide used in single photon emission computed tomography (SPECT). Two methods were devised to verify the nuclide-dependence of the gamma camera. In order to test the energy correction of the detectors, the first approach was based on the evaluation of the intrinsic non-uniformity and on the production of images with asymmetrical energy window. The second method was based on the production of correction matrices for different radionuclides, as well as on the subsequent application to phantom data that were also generated with different radionuclides. The investigation of a dualhead gamma camera produced the same results with both methods. One detector head was found to be weakly dependent on the radionuclide, due to the insufficient quality of energy correction. In this case, the phantom or patient data should be corrected using a uniformity correction matrix measured with the same radionuclide. The second detector remained nuclide-independent; in this case the uniformity correction matrix acquired for only one radionuclide was sufficient.

  6. High-resolution reconstruction for 3D SPECT

    NASA Astrophysics Data System (ADS)

    Li, Tianfang; Wen, Junhai; Lu, Hongbing; Li, Xiang; Liang, Zhengrong

    2003-05-01

    In this work, we have developed a new method for SPECT (single photon emission computed tomography) image reconstruction, which has shown the potential to provide higher resolution results than any other conventional methods using the same projection data. Unlike the conventional FBP- (filtered backprojection) and EM- (expectation maximization) type algorithms, we utilize as much system response information as we can during the reconstruction process. This information can be pre-measured during the calibration process and stored in the computer. By selecting different sampling schemes for the point response measurement, different system kernel matrices are obtained. Reconstruction utilizing these kernels generates a set of reconstructed images of the same source. Based on these reconstructed images and their corresponding sampling schemes, we are able to achieve a high resolution final image that best represents the object. Because a uniform attenuation, resolution variation and some other effects are included during the formation of the system kernel matrices, the reconstruction from the acquired projection data also compensates for all these effects correctly.

  7. Development of a Germanium Small-Animal SPECT System

    PubMed Central

    Johnson, Lindsay C.; Ovchinnikov, Oleg; Shokouhi, Sepideh; Peterson, Todd E.

    2015-01-01

    Advances in fabrication techniques, electronics, and mechanical cooling systems have given rise to germanium detectors suitable for biomedical imaging. We are developing a small-animal SPECT system that uses a double-sided Ge strip detector. The detector’s excellent energy resolution may help to reduce scatter and simplify processing of multi-isotope imaging, while its ability to measure depth of interaction has the potential to mitigate parallax error in pinhole imaging. The detector’s energy resolution is <1% FWHM at 140 keV and its spatial resolution is approximately 1.5 mm FWHM. The prototype system described has a single-pinhole collimator with a 1-mm diameter and a 70-degree opening angle with a focal length variable between 4.5 and 9 cm. Phantom images from the gantry-mounted system are presented, including the NEMA NU-2008 phantom and a hot-rod phantom. Additionally, the benefit of energy resolution is demonstrated by imaging a dual-isotope phantom with 99mTc and 123I without cross-talk correction. PMID:26755832

  8. MIRD pamphlet No. 23: quantitative SPECT for patient-specific 3-dimensional dosimetry in internal radionuclide therapy.

    PubMed

    Dewaraja, Yuni K; Frey, Eric C; Sgouros, George; Brill, A Bertrand; Roberson, Peter; Zanzonico, Pat B; Ljungberg, Michael

    2012-08-01

    In internal radionuclide therapy, a growing interest in voxel-level estimates of tissue-absorbed dose has been driven by the desire to report radiobiologic quantities that account for the biologic consequences of both spatial and temporal nonuniformities in these dose estimates. This report presents an overview of 3-dimensional SPECT methods and requirements for internal dosimetry at both regional and voxel levels. Combined SPECT/CT image-based methods are emphasized, because the CT-derived anatomic information allows one to address multiple technical factors that affect SPECT quantification while facilitating the patient-specific voxel-level dosimetry calculation itself. SPECT imaging and reconstruction techniques for quantification in radionuclide therapy are not necessarily the same as those designed to optimize diagnostic imaging quality. The current overview is intended as an introduction to an upcoming series of MIRD pamphlets with detailed radionuclide-specific recommendations intended to provide best-practice SPECT quantification-based guidance for radionuclide dosimetry.

  9. Diagnoses behind patients with hard-to-classify tremor and normal DaT-SPECT: a clinical follow up study

    PubMed Central

    Menéndez-González, Manuel; Tavares, Francisco; Zeidan, Nahla; Salas-Pacheco, José M.; Arias-Carrión, Oscar

    2014-01-01

    The [123I]ioflupane—a dopamine transporter radioligand—SPECT (DaT-SPECT) has proven to be useful in the differential diagnosis of tremor. Here, we investigate the diagnoses behind patients with hard-to-classify tremor and normal DaT-SPECT. Therefore, 30 patients with tremor and normal DaT-SPECT were followed up for 2 years. In 18 cases we were able to make a diagnosis. The residual 12 patients underwent a second DaT-SPECT, were then followed for additional 12 months and thereafter the diagnosis was reconsidered again. The final diagnoses included cases of essential tremor, dystonic tremor, multisystem atrophy, vascular parkinsonism, progressive supranuclear palsy, corticobasal degeneration, fragile X–associated tremor ataxia syndrome, psychogenic parkinsonism, iatrogenic parkinsonism and Parkinson's disease. However, for 6 patients the diagnosis remained uncertain. Larger series are needed to better establish the relative frequency of the different conditions behind these cases. PMID:24744729

  10. Clinical Usefulness of SPECT-CT in Patients with an Unexplained Pain in Metal on Metal (MOM) Total Hip Arthroplasty.

    PubMed

    Berber, Reshid; Henckel, Johann; Khoo, Michael; Wan, Simon; Hua, Jia; Skinner, John; Hart, Alister

    2015-04-01

    SPECT-CT is increasingly used to assess painful knee arthroplasties. The aim of this study was to evaluate the clinical usefulness of SPECT-CT in unexplained painful MOM hip arthroplasty. We compared the diagnosis and management plan for 19 prosthetic MOM hips in 15 subjects with unexplained pain before and after SPECT-CT. SPECT-CT changed the management decision in 13 (68%) subjects, Chi-Square=5.49, P=0.24. In 6 subjects (32%) pain remained unexplained however the result reassured the surgeon to continue with non-operative management. SPECT-CT should be reserved as a specialist test to help identify possible causes of pain where conventional investigations have failed. It can help reassure surgeons making management decisions for patients with unexplained pain following MOM hip arthroplasty.

  11. Laser interaction based on resonance saturation (LIBORS): an alternative to inverse bremsstrahlung for coupling laser energy into a plasma.

    PubMed

    Measures, R M; Drewell, N; Cardinal, P

    1979-06-01

    Resonance saturation represents an efficient and rapid method of coupling laser energy into a gaseous medium. In the case of a plasma superelastic collision quenching of the laser maintained resonance state population effectively converts the laser beam energy into translational energy of the free electrons. Subsequently, ionization of the laser pumped species rapidly ensues as a result of both the elevated electron temperature and the effective reduction of the ionization energy for those atoms maintained in the resonance state by the laser radiation. This method of coupling laser energy into a plasma has several advantages over inverse bremsstrahlung and could therefore be applicable to several areas of current interest including plasma channel formation for transportation of electron and ion beams, x-ray laser development, laser fusion, negative ion beam production, and the conversion of laser energy to electricity.

  12. Higher-order corrections to electron-nucleus bremsstrahlung cross sections above a few MeV

    NASA Astrophysics Data System (ADS)

    Mangiarotti, A.; Martins, M. N.

    2016-08-01

    Despite the fact that the first calculations of nuclear bremsstrahlung cross sections were performed for relativistic electrons more than 80 years ago by Sauter, Bethe and Heitler, and Racah, a fully satisfactory solution to this problem is still missing up to the present day. Numerical approaches are impractical for electrons with energies above a few MeV because they require a prohibitively large number of partial waves. Analytic formulae need to describe simultaneously and accurately the interaction with the Coulomb field of the nucleus and the screening effect of the atomic electrons. In the present paper, a state-of-the-art analytic calculation will be discussed. In particular, higher-order corrections to the interaction with the Coulomb field of the nucleus, a subject seldom tackled in the past, are included and compared extensively with published data. The emerged difficulties will be highlighted, but unfortunately they can be overcome only with future large coordinated theoretical and experimental efforts.

  13. Simulation of generation of bremsstrahlung gamma quanta upon irradiation of thin metal films by ultra-intense femtosecond laser pulses

    SciTech Connect

    Andreev, Stepan N; Rukhadze, Anri A; Garanin, Sergey G; Yakutov, B P; Tarakanov, V P

    2010-06-23

    We report the results of simulations of generation of bremsstrahlung gamma quanta upon irradiation of a thin-film metal target by ultra-intense femtosecond laser pulses. It is shown by the example of a thin gold target that the mean electron energy is twenty five times higher than the mean energy of gamma quanta generated by them. A simple approximating formula is proposed, which establishes a one-to-one relation between these quantities. The angular distributions of electrons and gamma quanta are studied. It is shown that only the angular distribution of high-energy gamma quanta repeats the angular distribution of the electrons leaving the target. (interaction of laser radiation with matter. laser plasma)

  14. Production of isotopes and isomers with irradiation of Z = 47–50 targets by 23-MeV bremsstrahlung

    SciTech Connect

    Karamian, S. A.; Carroll, J. J.; Aksenov, N. V.; Albin, Yu. A.; Belov, A. G.; Bozhikov, G. A.; Dmitriev, S. N.; Starodub, G. Ya.

    2015-09-15

    The irradiations of Ag to Sn targets by bremsstrahlung generated with 23-MeV electron beams are performed at the MT-25 microtron. Gamma spectra of the induced activities have been measured and the yields of all detected radionuclides and isomers are carefully measured and analyzed. A regular dependence of yields versus changed reaction threshold is confirmed. Many isomers are detected and the suppression of the production probability is observed with growing product spin. Special peculiarities for the isomer-to-ground state ratios were deduced for the {sup 106m}Ag, {sup 108m}Ag, {sup 113m}In, {sup 115m}In, and {sup 123m}Sn isomers. The production of such nuclides as {sup 108m}Ag, {sup 115m}In, {sup 117g}In, and {sup 113m}Cd is of interest for applications, especially when economic methods are available.

  15. Measurements and effects of backstreaming ions produced at bremsstrahlung converter target in Dragon-I linear induction accelerator

    SciTech Connect

    Yu Haijun; Zhu Jun; Chen Nan; Xie Yutong; Jiang Xiaoguo; Jian Cheng

    2010-04-15

    Positive ions released from x-ray converter target impacted by electron beam of millimeter spot size can be trapped and accelerated in the incident beam's potential well. As the ions move upstream, the beam will be pinched first and then defocused at the target. Four Faraday cups are used to collect backstreaming ions produced at the bremsstrahlung converter target in Dragon-I linear induction accelerator (LIA). Experimental and theoretical results show that the backstreaming positive ions density and velocity are about 10{sup 21}/m{sup 3} and 2-3 mm/{mu}s, respectively. The theoretical and experimental results of electron beam envelope with ions and without ions are also presented. The discussions show that the backstreaming positive ions will not affect the electron beam focusing and envelope radius in Dragon-I LIA.

  16. Measurements and effects of backstreaming ions produced at bremsstrahlung converter target in Dragon-I linear induction accelerator

    NASA Astrophysics Data System (ADS)

    Yu, Haijun; Zhu, Jun; Chen, Nan; Xie, Yutong; Jiang, Xiaoguo; Jian, Cheng

    2010-04-01

    Positive ions released from x-ray converter target impacted by electron beam of millimeter spot size can be trapped and accelerated in the incident beam's potential well. As the ions move upstream, the beam will be pinched first and then defocused at the target. Four Faraday cups are used to collect backstreaming ions produced at the bremsstrahlung converter target in Dragon-I linear induction accelerator (LIA). Experimental and theoretical results show that the backstreaming positive ions density and velocity are about 1021/m3 and 2-3 mm/μs, respectively. The theoretical and experimental results of electron beam envelope with ions and without ions are also presented. The discussions show that the backstreaming positive ions will not affect the electron beam focusing and envelope radius in Dragon-I LIA.

  17. Measurements and effects of backstreaming ions produced at bremsstrahlung converter target in Dragon-I linear induction accelerator.

    PubMed

    Yu, Haijun; Zhu, Jun; Chen, Nan; Xie, Yutong; Jiang, Xiaoguo; Jian, Cheng

    2010-04-01

    Positive ions released from x-ray converter target impacted by electron beam of millimeter spot size can be trapped and accelerated in the incident beam's potential well. As the ions move upstream, the beam will be pinched first and then defocused at the target. Four Faraday cups are used to collect backstreaming ions produced at the bremsstrahlung converter target in Dragon-I linear induction accelerator (LIA). Experimental and theoretical results show that the backstreaming positive ions density and velocity are about 10(21)/m(3) and 2-3 mm/micros, respectively. The theoretical and experimental results of electron beam envelope with ions and without ions are also presented. The discussions show that the backstreaming positive ions will not affect the electron beam focusing and envelope radius in Dragon-I LIA.

  18. Measurements of the fast electron bremsstrahlung emission during electron cyclotron resonance heating in the HL-2A tokamak

    SciTech Connect

    Zhang, Y. P.; Liu, Yi; Song, X. Y.; Yuan, G. L.; Chen, W.; Ji, X. Q.; Ding, X. T.; Yang, J. W.; Zhou, J.; Li, X.; Yang, Q. W.; Duan, X. R.; Pan, C. H.; Liu, Y.

    2010-10-15

    A fast electron bremsstrahlung (FEB) diagnostic technique based on cadmium telluride (CdTe) detector has been developed recently in the HL-2A tokamak for measurements of the temporal evolution of FEB emission in the energy range of 10-200 keV. With a perpendicular viewing into the plasma on the equatorial plane, the hard x-ray spectra with eight different energy channels are measured. The discrimination of the spectra is implemented by an accurate spectrometry. The system also makes use of fast digitization and software signal processing technology. An ambient environment of neutrons, gammas, and magnetic disturbance requires careful shielding. During electron cyclotron resonance heating, the generation of fast electrons and the oscillations of electron fishbone (e-fishbone) have been found. Using the FEB measurement system, it has been experimentally identified that the mode strongly correlates with the electron cyclotron resonance heating produced fast electrons with 30-70 keV.

  19. Electron Bremsstrahlung Hard X-Ray Spectra, Electron Distributions and Energetics in the 2002 July 23 Solar Flare

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.; Sui, Lindhui; Schartz, Richard A.; Emslie, A. Gordon; Oegerle, William (Technical Monitor)

    2003-01-01

    We present and analyze the first high-resolution hard X-ray spectra from a solar flare observed in both X-ray/gamma-ray continuum and gamma-ray lines. The 2002 July 23 flare was observed by the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The spatially integrated photon flux spectra are well fitted between 10 and 300 keV by the combination of an isothermal component and a double power law. The flare plasma temperature peaks at 40 MK around the time of peak hard X-ray emission and remains above 20 MK 37 min later. We derive the evolution of the nonthermal mean electron flux distribution by directly fitting the RHESSI X-ray spectra with the thin-target bremsstrahlung from a double power-law electron distribution with a low-energy cutoff. We also derive the evolution of the electron flux distribution on the assumption that the emission is thick-target bremsstrahlung. We find that the injected nonthermal electrons are well described throughout the flare by this double power-law distribution with a low-energy cutoff that is typically between 20-40 keV. Using our thick-target results, we compare the energy contained in the nonthermal electrons with the energy content of the thermal flare plasma observed by RHESSI and GOES. We find that the minimum total energy deposited into the flare plasma by nonthermal electrons, 2.6 x 10(exp 31)erg, is on the order of and possibly less than the energy in the thermal plasma. However, these fits do not rule out the possibility that the energy in nonthermal electrons exceeds the energy in the thermal plasma.

  20. Electron Bremsstrahlung Hard X-Ray Spectra, Electron Distributions and Energetics in the 2002 July 23 Solar Flare

    NASA Technical Reports Server (NTRS)

    Holman, G. D.; Sui, L.; Schwartz, R. A.; Emslie, A. G.

    2003-01-01

    We present and analyze the first high-resolution hard X-ray spectra from a solar flare observed in both X-ray/gamma-ray continuum and gamma-ray lines. The 2002 July 23 flare was observed by the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The spatially integrated photon flux spectra are well fitted between 10 and 300 keV by the combination of an isothermal component and a double power law. The flare plasma temperature peaks at 40 MK around the time of peak hard X-ray emission and remains above 20 MK 37 min later. We derive the evolution of the nonthermal mean electron flux distribution by directly fitting the RHESSI X-ray spectra with the thin-target bremsstrahlung from a double power-law electron distribution with a low-energy cutoff. We also derive the evolution of the electron flux distribution on the assumption that the emission is thick-target bremsstrahlung. We find that the injected nonthermal electrons are well described throughout the flare by this double power-law distribution with a low-energy cutoff that is typically between 20 - 40 keV. Using our thick-target results, we compare the energy contained in the nonthermal electrons with the energy content of the thermal flare plasma observed by RHESSI and GOES. We find that the minimum total energy deposited into the flare plasma by nonthermal electrons, 2.6 x 10(exp 31) erg, is on the order of and possibly less than the energy in the thermal plasma. However, these fits do not rule out the possibility that the energy in nonthermal electrons exceeds the energy in the thermal plasma. This work was supported in part by the RHESSI Project and the NASA Sun-Earth Connection program.

  1. Blind deconvolution of human brain SPECT images using a distribution mixture estimation

    NASA Astrophysics Data System (ADS)

    Mignotte, Max; Meunier, Jean

    2000-06-01

    Thanks to its ability to yield functionally-based information, the SPECT imagery technique has become a great help in the diagnostic of cerebrovascular diseases. Nevertheless, due to the imaging process, SPECT images are blurred and consequently their interpretation by the clinician is often difficult. In order to improve the spatial resolution of these images and then to facilitate their interpretation, we propose herein to implement a deconvolution procedure relying on an accurate distribution mixture parameter estimation procedure. Parameters of this distribution mixture are efficiently exploited in order to prevent overfitting of the noisy data or to determine the support of the object to be deconvolved when this one is needed. In this context, we compare the deconvolution results obtained by the Lucy-Richardson method and by the recent blind deconvolution technique called the NAS-RIF algorithm on real and simulated brain SPECT images. The NAS-RIF performs the best and shows significant contrast enhancement with little mottle (noise) amplification.

  2. Drug Development in Alzheimer’s Disease: The Contribution of PET and SPECT

    PubMed Central

    Declercq, Lieven D.; Vandenberghe, Rik; Van Laere, Koen; Verbruggen, Alfons; Bormans, Guy

    2016-01-01

    Clinical trials aiming to develop disease-altering drugs for Alzheimer’s disease (AD), a neurodegenerative disorder with devastating consequences, are failing at an alarming rate. Poorly defined inclusion-and outcome criteria, due to a limited amount of objective biomarkers, is one of the major concerns. Non-invasive molecular imaging techniques, positron emission tomography and single photon emissio