scholarly journals Simple model for estimation of absorbed dose by organs and tumors after PRRT from a single SPECT/CT study

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Alexandre Chicheportiche ◽  
Moshe Sason ◽  
Jeremy Godefroy ◽  
Yodphat Krausz ◽  
Mahmoud Zidan ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Bone Marrow ◽  
Activity Concentration ◽  
Absorbed Dose ◽  
The Body ◽  
Emission Computed Tomography ◽  
Standard Protocol ◽  
Independent Variables ◽  
Absorbed Doses ◽  
Mlr Model

Abstract Background Following each cycle of peptide receptor radionuclide therapy (PRRT), absorbed doses by tumors and normal organs are typically calculated from three quantitative single-photon emission computed tomography (SPECT)/computed tomography (CT) studies acquired at t1 = 24 h, t2 = 96 h, t3 = 168 h after the first cycle of treatment and from a single study at t1 after the subsequent cycles. In the present study, we have assessed the feasibility of a single SPECT/CT study after each PRRT cycle using a trained multiple linear regression (MLR) model for absorbed dose calculation and have evaluated its impact on patient management. Quantitative [177Lu]-DOTA-TATE SPECT/CT data after PRRT of seventy-two consecutive metastatic neuroendocrine tumors patients were retrospectively evaluated. A set of 40 consecutive studies was used to train the MLR model. The two independent variables of the model included the time of imaging after administration of the treatment and the radiopharmaceutical activity concentration in a given  organ/tumor. The dependent variable was the dose absorbed by the organ/tumor obtained with the standard protocol. For bone marrow dosimetry, the independent variables included the time of imaging, and the blood and remainder of the body activity concentration. The model was evaluated in 32 consecutive patients. Absorbed doses were assessed for kidneys, bone marrow, liver, spleen and tumor sites. Results There was no difference in management decisions, whether PRRT can be safely continued or not because unsafe absorbed dose to risk organs between the standard and the MLR model-based protocol using a single SPECT/CT study performed at t3 = 168 h after the first cycle and at t1 = 24 h after the subsequent cycles. Cumulative absorbed doses were obtained with mean relative differences of − 0.5% ± 5.4%, 1.6% ± 15.1%, − 6.2% ± 7.3%, − 5.5% ± 5.8% and 2.9% ± 12.7% for kidneys, bone marrow, liver, spleen and tumors, respectively (Pearson’s r correlation coefficient 0.99, 0.91, 0.99, 0.99 and 0.97, respectively). Conclusion Dosimetry calculations using a MLR model with a single SPECT/CT study are in good agreement with the standard protocol, while avoiding the use of dosimetry software and enabling improved patient comfort and reduced scanner and staff time.

scholarly journals Evaluation of the 223Ra-dichloride biodistribution models for the assessment of the doses from internal exposure

2020 ◽  
Vol 2 (1) ◽  
pp. 54-69
Author(s):  
Aleksandr V. Vodovatov ◽  
Larisa A. Chipiga ◽  
Anna E. Petrova ◽  
Andrey A. Stanzhevsky
Keyword(s):  
Prostate Cancer ◽  
Bone Marrow ◽  
Bone Metastases ◽  
Absorbed Dose ◽  
The Body ◽  
Internal Exposure ◽  
Bone Surface ◽  
Red Bone Marrow ◽  
Absorbed Doses ◽  
Healthy Part

Prostate cancer is the most common men urogenital tumor. For most patients with the disseminated neoplastic process in the prostate after the hormonal therapy, the disease gradually progresses in the form of castration-resistant prostate cancer (mCRPC). The use of 223Ra agents is aimed at the treatment of the bone lesions as part of palliative therapy. The physical properties of 223Ra significantly complicate the require direct radiometry for patients with alpha emitters. Hence, the distribution of 223Ra in the body should be evaluated based on the dedicated biodistribution models. The aim of this study was to review and analyze the existing approaches to the evaluation of the biodistribution of 223Ra and its pharmaceutical forms (223Ra-dichloride) for the further assessment of absorbed doses in radiosensitive organs and tissues. The study includes the mathematical models for the estimation of the absorbed doses in various organs and tissues of the body. A review of three different 223Ra biodistribution models is presented: two ICRP models for occupational exposure and a model based on the results of an experimental assessment of 223Ra distribution in patients with mCRPC. It was indicated that the latter model is in good agreement with the results of direct radiometry of patients. A significant drawback of all models is the simulation of the red bone marrow and bone surface as single chambers. During the radionuclide therapy, 223Ra will specifically accumulate in bone metastases, instead of being evenly distributed in the skeleton. Hence, the use of any of the reviewed models will lead both to a significant overestimation of the absorbed dose in a healthy part of the bone surface and red bone marrow, and to an underestimation of the absorbed dose in bone metastases. Currently, this problem has not been solved. That requires the development of new improved models that consider the accumulation of 223Ra in the healthy part of the skeleton and in skeletal metastases.

scholarly journals Dosimetry in CBCT with Different Protocols: Emphasis on Small FOVs Including Exams for TMJ

2017 ◽  
Vol 28 (4) ◽  
pp. 511-516 ◽  
Author(s):  
Helena Aguiar Ribeiro Nascimento ◽  
Marcos Ely Almeida Andrade ◽  
Marco Antonio Gomes Frazão ◽  
Eduarda Helena Leandro Nascimento ◽  
Flavia Maria Moraes Ramos-Perez ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Great Influence ◽  
Absorbed Dose ◽  
Skin Surface ◽  
Field Of View ◽  
Cone Beam ◽  
Anthropomorphic Phantom ◽  
Thermoluminescent Dosimeters ◽  
Absorbed Doses ◽  
Mode Size

Abstract This study aimed to estimate the absorbed dose in cone beam computed tomography (CBCT) exams according to different exposure parameters and size and position of the field of view (FOV). In addition was compared the absorbed dose of two smaller FOV scans with that of a larger FOV scan for evaluation of temporomandibular joint (TMJ), as it is a bilateral structure. CBCT scans were obtained on OP300 Maxio unit varying scanning mode (standard, high and endo) as well as size (5x5, 6x8 and 8x15 cm) and positioning of FOV. With a small FOV, different areas were scanned (maxilla or mandible, anterior or posterior and TMJ). Absorbed doses were determined using thermoluminescent dosimeters on the skin surface of sensitive organs of an anthropomorphic phantom. Endo mode showed the highest dose, followed by the high and standard modes in all FOV positions. With small FOV, doses were higher in the posterior region, especially in the mandible. Dose reduction occurred when small FOVs were used, but it was not proportional to FOV size reduction. For TMJ, the dose in a single acquisition with large FOV was greater than two acquisitions with small FOV, but lower than two acquisitions with medium FOV (6x8 cm). In conclusion, scanning mode, size and FOV position have great influence on the absorbed dose. Small FOV decreases the dose, but there is no linear relation between FOV size and dose. For bilateral exams of TMJ, double acquisition with small FOVs produces decrease in absorbed dose relative to a large FOV.

scholarly journals EANM dosimetry committee series on standard operational procedures: a unified methodology for 99mTc-MAA pre- and 90Y peri-therapy dosimetry in liver radioembolization with 90Y microspheres

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Carlo Chiesa ◽  
Katarina Sjogreen-Gleisner ◽  
Stephan Walrand ◽  
Lidia Strigari ◽  
Glenn Flux ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Single Photon ◽  
Photon Emission ◽  
Absorbed Dose ◽  
Calibration Method ◽  
Emission Computed Tomography ◽  
Pet Ct ◽  
Improve Calculation ◽  
Voxel Dosimetry ◽  
Lung Shunt

AbstractThe aim of this standard operational procedure is to standardize the methodology employed for the evaluation of pre- and post-treatment absorbed dose calculations in 90Y microsphere liver radioembolization. Basic assumptions include the permanent trapping of microspheres, the local energy deposition method for voxel dosimetry, and the patient–relative calibration method for activity quantification.The identity of 99mTc albumin macro-aggregates (MAA) and 90Y microsphere biodistribution is also assumed. The large observed discrepancies in some patients between 99mTc-MAA predictions and actual 90Y microsphere distributions for lesions is discussed. Absorbed dose predictions to whole non-tumoural liver are considered more reliable and the basic predictors of toxicity. Treatment planning based on mean absorbed dose delivered to the whole non-tumoural liver is advised, except in super-selective treatments.Given the potential mismatch between MAA simulation and actual therapy, absorbed doses should be calculated both pre- and post-therapy. Distinct evaluation between target tumours and non-tumoural tissue, including lungs in cases of lung shunt, are vital for proper optimization of therapy. Dosimetry should be performed first according to a mean absorbed dose approach, with an optional, but important, voxel level evaluation. Fully corrected 99mTc-MAA Single Photon Emission Computed Tomography (SPECT)/computed tomography (CT) and 90Y TOF PET/CT are regarded as optimal acquisition methodologies, but, for institutes where SPECT/CT is not available, non-attenuation corrected 99mTc-MAA SPECT may be used. This offers better planning quality than non dosimetric methods such as Body Surface Area (BSA) or mono-compartmental dosimetry. Quantitative 90Y bremsstrahlung SPECT can be used if dedicated correction methods are available.The proposed methodology is feasible with standard camera software and a spreadsheet. Available commercial or free software can help facilitate the process and improve calculation time.

scholarly journals Autologous bone marrow-derived mononuclear cell therapy in three patients with severe asthma​

2020 ◽  
Author(s):  
Fabio S. Aguiar ◽  
André S. Melo ◽  
Ana Maria Silva Araújo ◽  
Alexandre Pinto Cardoso ◽  
Sergio A. Lopes de Souza ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Computed Tomography ◽  
Bone Marrow ◽  
Lung Function ◽  
Severe Asthma ◽  
Mononuclear Cell ◽  
Case Series ◽  
Emission Computed Tomography ◽  
Therapeutic Effects

Abstract Background: Despite recent advances in understanding its pathophysiology and development of novel therapies, asthma remains a serious public health issue worldwide. Combination therapy with inhaled corticosteroids and long-acting β2-adrenoceptor agonists results in disease control for many patients, but those who exhibit severe asthma are often unresponsive to conventional treatment, experiencing worse quality of life, frequent exacerbations, and increasing healthcare costs. Bone marrow-derived mononuclear cell (BMMC) transplantation has been shown to reduce airway inflammation and remodeling and improve lung function in experimental models of allergic asthma. However, to date, no study has evaluated the therapeutic effects of BMMCs in patients with severe asthma. Methods: This is a case series of three patients who presented with severe asthma unresponsive to conventional therapy and omalizumab. All received a single intravenous dose of autologous BMMCs (2×107) and were periodically evaluated for 1 year after the procedure. Endpoint assessments included physical examination; quality of life questionnaires; imaging (computed tomography, single-photon emission computed tomography, and ventilation/perfusion scan); lung function tests; and a 6-min walk test.Results: All patients completed the follow-up protocol. No serious adverse events attributable to BMMC transplantation were observed during or after the procedure. Lung function remained stable throughout. A slight increase in ventilation of the right lung was observed on day 120 after BMMC transplantation in one patient. All three patients reported improvement in quality of life in the early post-procedure course. Conclusions: This paper is the first to describe the effects of BMMC therapy in patients with severe asthma, providing a basis for subsequent trials to assess efficacy.

scholarly journals Single-Photon Emission Computed Tomography (SPECT) Radiopharmaceuticals

2021 ◽  
Author(s):  
Syed Ali Raza Naqvi ◽  
Muhammad Babar Imran
Keyword(s):  
Computed Tomography ◽  
Single Photon ◽  
Photon Emission ◽  
The Body ◽  
Emission Computed Tomography ◽  
Single Photon Emission ◽  
Emission Computed ◽  
Single Photon Emission Computed ◽  
Radiolabeled Compounds ◽  
Photon Emission Computed Tomography

Nuclear medicine techniques have a great deal of advantage of using gamma radiation emitter radiolabeled compounds to diagnose the long list of infectious and malignant disorders in human systems. The gamma emitter radionuclide-labeled compounds are associated with single photon emission computed tomography (SPECT) camera. SPECT camera mainly offers the detection and analysis of gamma rays origin to furnish the imaging of defective organs in the body. There are about 85% radiopharmaceuticals in clinical practice which are being detected by SPECT camera. The following chapter is an update about the SPECT radiopharmaceuticals that were developed and tried for infection and cancer diagnosis.

scholarly journals Dismantling the pathophysiology of asthma using imaging

2019 ◽  
Vol 28 (152) ◽  
pp. 180111 ◽  
Author(s):  
Gregory G. King ◽  
Catherine E. Farrow ◽  
David G. Chapman
Keyword(s):  
Computed Tomography ◽  
Single Photon ◽  
Photon Emission ◽  
Airflow Obstruction ◽  
Three Dimensional ◽  
The Body ◽  
Lung Imaging ◽  
Current Evidence ◽  
Emission Computed Tomography ◽  
Positron Emission

Asthma remains an important disease worldwide, causing high burden to patients and healthcare systems and presenting a need for better management and ultimately prevention and cure. Asthma is a very heterogeneous condition, with many different pathophysiological processes. Better measurement of those pathophysiological processes are needed to better phenotype disease, and to go beyond the current, highly limited measurements that are currently used: spirometry and symptoms. Sophisticated three-dimensional lung imaging using computed tomography and ventilation imaging (single photon emission computed tomography and positron emission tomography) and magnetic resonance imaging and methods of lung imaging applicable to asthma research are now highly developed. The body of current evidence suggests that abnormalities in structure and ventilatory function measured by imaging are clinically relevant, given their associations with disease severity, exacerbation risk and airflow obstruction. Therefore, lung imaging is ready for more widespread use in clinical trials and to become part of routine clinical assessment of asthma.

scholarly journals Preclinical Evaluation of 99mTc-Labeled GRPR Antagonists maSSS/SES-PEG2-RM26 for Imaging of Prostate Cancer

Pharmaceutics ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 182
Author(s):  
Ayman Abouzayed ◽  
Sara S. Rinne ◽  
Hamideh Sabahnoo ◽  
Jens Sörensen ◽  
Vladimir Chernov ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Computed Tomography ◽  
Single Photon ◽  
Specific Binding ◽  
Photon Emission ◽  
Absorbed Dose ◽  
Single Step ◽  
Emission Computed Tomography

Background: Gastrin-releasing peptide receptor (GRPR) is an important target for imaging of prostate cancer. The wide availability of single-photon emission computed tomography/computed tomography (SPECT/CT) and the generator-produced 99mTc can be utilized to facilitate the use of GRPR-targeting radiotracers for diagnostics of prostate cancers. Methods: Synthetically produced mercaptoacetyl-Ser-Ser-Ser (maSSS)-PEG2-RM26 and mercaptoacetyl-Ser-Glu-Ser (maSES)-PEG2-RM26 (RM26 = d-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2) were radiolabeled with 99mTc and characterized in vitro using PC-3 cells and in vivo, using NMRI or PC-3 tumor bearing mice. SPECT/CT imaging and dosimetry calculations were performed for [99mTc]Tc-maSSS-PEG2-RM26. Results: Peptides were radiolabeled with high yields (>98%), demonstrating GRPR specific binding and slow internalization in PC-3 cells. [99mTc]Tc-maSSS-PEG2-RM26 outperformed [99mTc]Tc-maSES-PEG2-RM26 in terms of GRPR affinity, with a lower dissociation constant (61 pM vs 849 pM) and demonstrating higher tumor uptake. [99mTc]Tc-maSSS-PEG2-RM26 had tumor-to-blood, tumor-to-muscle, and tumor-to-bone ratios of 97 ± 56, 188 ± 32, and 177 ± 79, respectively. SPECT/CT images of [99mTc]Tc-maSSS-PEG2-RM26 clearly visualized the GRPR-overexpressing tumors. The dosimetry estimated for [99mTc]Tc-maSSS-PEG2-RM26 showed the highest absorbed dose in the small intestine (1.65 × 10−3 mGy/MBq), and the effective dose is 3.49 × 10−3 mSv/MBq. Conclusion: The GRPR antagonist maSSS-PEG2-RM26 is a promising GRPR-targeting agent that can be radiolabeled through a single-step with the generator-produced 99mTc and used for imaging of GRPR-expressing prostate cancer.

scholarly journals Imaging of Multiple Myeloma

2019 ◽  
Vol 191 (09) ◽  
pp. 805-816
Author(s):  
Aleksander Kosmala ◽  
Thorsten Bley ◽  
Bernhard Petritsch
Keyword(s):  
Computed Tomography ◽  
Multiple Myeloma ◽  
Bone Marrow ◽  
Imaging Techniques ◽  
Therapy Monitoring ◽  
Whole Body ◽  
Emission Computed Tomography ◽  
Cross Sectional ◽  
Therapeutic Implications

Background Multiple myeloma is a malignant hematological disease characterized by uncontrolled proliferation of monoclonal plasma cells mainly in the bone marrow. Imaging plays a crucial role in diagnosis and follow-up. Method This literature review provides information about multiple myeloma, its precursor diseases, and available imaging techniques. Advantages and limitations as well as possible prognostic and therapeutic implications of the different imaging methods are presented in the context of the current literature. Results and Conclusion Cross-sectional imaging has replaced conventional X-ray skeletal survey. Widely available whole-body computed tomography is routinely used to detect osteolytic lesions. Magnetic resonance imaging is the most sensitive technique to identify bone marrow infiltration and is recommended in multiple myeloma precursor diseases. Positron emission computed tomography combines morphological and functional imaging. It is mainly used for follow-up, therapy monitoring, and response evaluation. Key points:  Citation Format

scholarly journals Hibrid képalkotás: klinikai evidenciák, lehetőségek

2015 ◽  
Vol 156 (52) ◽  
pp. 2110-2115
Author(s):  
György Trencsényi ◽  
Sándor Kristóf Barna ◽  
Ildikó Garai
Keyword(s):  
Computed Tomography ◽  
Hybrid Imaging ◽  
Single Photon ◽  
Photon Emission ◽  
Research Process ◽  
Clinical Diagnostics ◽  
The Body ◽  
Drug Candidate ◽  
Emission Computed Tomography

Nowadays the hybrid imaging technologies which combine the modern equipments of radiology and nuclear medicine play an important role in both the translational research process and clinical diagnostics. Among the routine diagnostic imaging procedures positron emission tomography and single photon emission computed tomography combined with computed tomography or magnetic resonance imaging currently belong to the most advanced techniques allowing that functional and morphological images can be superimposed on each other in the same position. The hybrid imaging equipments provide useful information about the pathological processes in the body due to their high sensibility and resolution. Furthermore, with the help of these imaging modalities we can get acquainted with the biochemical and pathobiochemical processes that are essential for understanding and treating diseases, or getting acquainted with the behaviour of a new drug candidate. With the help of the clinical and preclinical non-invasive in vivo molecular imaging systems the drug developing process can be shortened and its costs can be reduced. Orv. Hetil., 2015, 156(52), 2110–2115.

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