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On the use of solid 133Ba sources as surrogate for liquid 131I in SPECT/CT calibration: a European multi-centre evaluation. EJNMMI Phys 2023; 10:73. [PMID: 37993667 PMCID: PMC10665282 DOI: 10.1186/s40658-023-00582-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 09/25/2023] [Indexed: 11/24/2023] Open
Abstract
INTRODUCTION Commissioning, calibration, and quality control procedures for nuclear medicine imaging systems are typically performed using hollow containers filled with radionuclide solutions. This leads to multiple sources of uncertainty, many of which can be overcome by using traceable, sealed, long-lived surrogate sources containing a radionuclide of comparable energies and emission probabilities. This study presents the results of a quantitative SPECT/CT imaging comparison exercise performed within the MRTDosimetry consortium to assess the feasibility of using 133Ba as a surrogate for 131I imaging. MATERIALS AND METHODS Two sets of four traceable 133Ba sources were produced at two National Metrology Institutes and encapsulated in 3D-printed cylinders (volume range 1.68-107.4 mL). Corresponding hollow cylinders to be filled with liquid 131I and a mounting baseplate for repeatable positioning within a Jaszczak phantom were also produced. A quantitative SPECT/CT imaging comparison exercise was conducted between seven members of the consortium (eight SPECT/CT systems from two major vendors) based on a standardised protocol. Each site had to perform three measurements with the two sets of 133Ba sources and liquid 131I. RESULTS As anticipated, the 131I pseudo-image calibration factors (cps/MBq) were higher than those for 133Ba for all reconstructions and systems. A site-specific cross-calibration reduced the performance differences between both radionuclides with respect to a cross-calibration based on the ratio of emission probabilities from a median of 12-1.5%. The site-specific cross-calibration method also showed agreement between 133Ba and 131I for all cylinder volumes, which highlights the potential use of 133Ba sources to calculate recovery coefficients for partial volume correction. CONCLUSION This comparison exercise demonstrated that traceable solid 133Ba sources can be used as surrogate for liquid 131I imaging. The use of solid surrogate sources could solve the radiation protection problem inherent in the preparation of phantoms with 131I liquid activity solutions as well as reduce the measurement uncertainties in the activity. This is particularly relevant for stability measurements, which have to be carried out at regular intervals.
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Safety injections of nuclear medicine radiotracers: towards a new modality for a real-time detection of extravasation events and 18F-FDG SUV data correction. EJNMMI Phys 2023; 10:31. [PMID: 37221434 DOI: 10.1186/s40658-023-00556-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 05/15/2023] [Indexed: 05/25/2023] Open
Abstract
BACKGROUND 18F-FDG PET/CT imaging allows to study oncological patients and their relative diagnosis through the standardised uptake value (SUV) evaluation. During radiopharmaceutical injection, an extravasation event may occur, making the SUV value less accurate and possibly leading to severe tissue damage. The study aimed to propose a new technique to monitor and manage these events, to provide an early evaluation and correction to the estimated SUV value through a SUV correction coefficient. METHODS A cohort of 70 patients undergoing 18F- FDG PET/CT examinations was enrolled. Two portable detectors were secured on the patients' arms. The dose-rate (DR) time curves on the injected DRin and contralateral DRcon arm were acquired during the first 10 min of injection. Such data were processed to calculate the parameters ΔpinNOR = (DRinmax- DRinmean)/DRinmax and ΔRt = (DRin(t) - DRcon(t)), where DRinmax is the maximum DR value, DRinmean is the average DR value in the injected arm. OLINDA software allowed dosimetric estimation of the dose in the extravasation region. The estimated residual activity in the extravasation site allowed the evaluation of the SUV's correction value and to define an SUV correction coefficient. RESULTS Four cases of extravasations were identified for which ΔRt [(390 ± 26) µSv/h], while ΔRt [(150 ± 22) µSv/h] for abnormal and ΔRt [(24 ± 11) µSv/h] for normal cases. The ΔpinNOR showed an average value of (0.44 ± 0.05) for extravasation cases and an average value of (0.91 ± 0.06) and (0.77 ± 0.23) in normal and abnormal classes, respectively. The percentage of SUV reduction (SUV%CR) ranges between 0.3% and 6%. The calculated self-tissue dose values range from 0.027 to 0.573 Gy, according to the segmentation modality. A similar correlation between the inverse of ΔpinNOR and the normalised ΔRt with the SUV correction coefficient was found. CONCLUSIONS The proposed metrics allowed to characterised the extravasation events in the first few minutes after the injection, providing an early SUV correction when necessary. We also assume that the characterisation of the DR-time curve of the injection arm is sufficient for the detection of extravasation events. Further validation of these hypotheses and key metrics is recommended in larger cohorts.
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Predictive and Prognostic Role of Pre-Therapy and Interim 68Ga-DOTATOC PET/CT Parameters in Metastatic Advanced Neuroendocrine Tumor Patients Treated with PRRT. Cancers (Basel) 2022; 14:cancers14030592. [PMID: 35158862 PMCID: PMC8833820 DOI: 10.3390/cancers14030592] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 01/18/2022] [Accepted: 01/22/2022] [Indexed: 12/11/2022] Open
Abstract
Simple Summary Although a significant improvement has been achieved in the management of metastatic neuroendocrine tumor (NET), disease progression is observed in 20–30% of patients treated with peptide receptor radionuclide therapy (PRRT). Therefore, the early identification of patients who are at high risk of treatment failure is important to avoid futile therapy toxicities. The aim of this study was to identify biomarkers derived from baseline and interim 68Ga-DOTATOC PET/CT in patients undergoing PRRT. In 46 metastatic NET patients with available baseline and interim PET, only baseline total tumor volume (bTV) was able to discriminate responders to PRRT (partial response or stable disease) vs. non-responders. Patients with high bTV had also the worst overall survival. bTV, an imaging biomarker, integrated in the initial workup of NET patients could improve risk stratification and contribute to a tailored therapy approach. Abstract Peptide receptor radionuclide therapy (PRRT) is an effective therapeutic option in patients with metastatic neuroendocrine tumor (NET). However, PRRT fails in about 15–30% of cases. Identification of biomarkers predicting the response to PRRT is essential for treatment tailoring. We aimed to evaluate the predictive and prognostic role of semiquantitative and volumetric parameters obtained from the 68Ga-DOTATOC PET/CT before therapy (bPET) and after two cycles of PRRT (iPET). A total of 46 patients were included in this retrospective analysis. The primary tumor was 78% gastroenteropancreatic (GEP), 13% broncho-pulmonary and 9% of unknown origin. 35 patients (76.1%) with stable disease or partial response after PRRT were classified as responders and 11 (23.9%) as non-responders. Logistic regression analysis identified that baseline total volume (bTV) was associated with therapy outcome (OR 1.17; 95%CI 1.02–1.32; p = 0.02). No significant association with PRRT response was observed for other variables. High bTV was confirmed as the only variable independently associated with OS (HR 12.76, 95%CI 1.53–107, p = 0.01). In conclusion, high bTV is a negative predictor for PRRT response and is associated with worse OS rates. Early iPET during PRRT apparently does not provide information useful to change the management of NET patients.
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Evaluation of a novel data-driven respiratory gating technique in PET/CT exams. Phys Med 2021. [DOI: 10.1016/s1120-1797(22)00039-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Radiomic features characterization in healthy and NSCLC tissues. Phys Med 2021. [DOI: 10.1016/s1120-1797(22)00400-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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How direct measurements of worker eyes with a Scheimpflug camera can affect lensdose coefficients in interventional radiology. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2021; 41:689-706. [PMID: 33827064 DOI: 10.1088/1361-6498/abf56f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 04/07/2021] [Indexed: 06/12/2023]
Abstract
The 2013/59/Euratom Directive reduced the occupational exposure limits for the lens. Since it has become crucial to estimate the dose absorbed by the lens, we have studied the individual variability of exposed workers' ocular conformations with respect to the data estimated from their personal dosimetry. The anterior eye conformations of 45 exposed workers were acquired using Scheimpflug imaging and classified according to their sight conditions (emmetropia, myopia or hypermetropia). Three eye models were computed, with two lens reconstructions, and implemented in an interventional radiology scenario using Monte Carlo code. The models were dosimetrically analysed by simulating setup A, a theoretical monoenergetic and isotropic photon source (10-150 keV) and setup B, a more realistic interventional setting with an angiographic x-ray unit (50, 75, 100 kV peak). Scheimpflug imaging provided an average anterior chamber depth of (6.4 ± 0.5) mm and a lens depth of (3.9 ± 0.3) mm, together with a reconstructed equatorial lens length of (7.1-10.1) mm. Using these data for model reconstruction, dose coefficients (DCs) were simulated for all ocular structures. Regardless of the eye model used, the DCs showed a similar trend with radiation energy, which highlighted that for the same energy and setup, no significant dependence on ocular morphology and workers' visual conditions was observed. The maximum difference obtained did not exceed 1% for all eye models or structures analysed. Therefore, the individual variabilities of worker ocular anatomy do not require any additional correction, compared to the personal dosimetry data measured with a dedicated lens dosimeter. To estimate the dose absorbed by the other eye structures, it is, instead, essential to know the spectrum of the source that has generated the irradiation, since there are differences between monoenergetic sources and more realistic angiographic units.
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A multicentre and multi-national evaluation of the accuracy of quantitative Lu-177 SPECT/CT imaging performed within the MRTDosimetry project. EJNMMI Phys 2021; 8:55. [PMID: 34297218 PMCID: PMC8302709 DOI: 10.1186/s40658-021-00397-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 06/21/2021] [Indexed: 11/10/2022] Open
Abstract
PURPOSE Patient-specific dosimetry is required to ensure the safety of molecular radiotherapy and to predict response. Dosimetry involves several steps, the first of which is the determination of the activity of the radiopharmaceutical taken up by an organ/lesion over time. As uncertainties propagate along each of the subsequent steps (integration of the time-activity curve, absorbed dose calculation), establishing a reliable activity quantification is essential. The MRTDosimetry project was a European initiative to bring together expertise in metrology and nuclear medicine research, with one main goal of standardizing quantitative 177Lu SPECT/CT imaging based on a calibration protocol developed and tested in a multicentre inter-comparison. This study presents the setup and results of this comparison exercise. METHODS The inter-comparison included nine SPECT/CT systems. Each site performed a set of three measurements with the same setup (system, acquisition and reconstruction): (1) Determination of an image calibration for conversion from counts to activity concentration (large cylinder phantom), (2) determination of recovery coefficients for partial volume correction (IEC NEMA PET body phantom with sphere inserts), (3) validation of the established quantitative imaging setup using a 3D printed two-organ phantom (ICRP110-based kidney and spleen). In contrast to previous efforts, traceability of the activity measurement was required for each participant, and all participants were asked to calculate uncertainties for their SPECT-based activities. RESULTS Similar combinations of imaging system and reconstruction lead to similar image calibration factors. The activity ratio results of the anthropomorphic phantom validation demonstrate significant harmonization of quantitative imaging performance between the sites with all sites falling within one standard deviation of the mean values for all inserts. Activity recovery was underestimated for total kidney, spleen, and kidney cortex, while it was overestimated for the medulla. CONCLUSION This international comparison exercise demonstrates that harmonization of quantitative SPECT/CT is feasible when following very specific instructions of a dedicated calibration protocol, as developed within the MRTDosimetry project. While quantitative imaging performance demonstrates significant harmonization, an over- and underestimation of the activity recovery highlights the limitations of any partial volume correction in the presence of spill-in and spill-out between two adjacent volumes of interests.
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PROGNOSTIC ROLE OF LESION DISSEMINATION FEATURE (DMAX) CALCULATED ON BASELINE PET/CT IN HODGKIN LYMPHOMA. Hematol Oncol 2021. [DOI: 10.1002/hon.20_2879] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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68Ga-DOTATOC PET/CT-Based Radiomic Analysis and PRRT Outcome: A Preliminary Evaluation Based on an Exploratory Radiomic Analysis on Two Patients. Front Med (Lausanne) 2021; 7:601853. [PMID: 33575262 PMCID: PMC7870479 DOI: 10.3389/fmed.2020.601853] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 12/16/2020] [Indexed: 12/12/2022] Open
Abstract
Aim: This work aims to evaluate whether the radiomic features extracted by 68Ga-DOTATOC-PET/CT of two patients are associated with the response to peptide receptor radionuclide therapy (PRRT) in patients affected by neuroendocrine tumor (NET). Methods: This is a pilot report in two NET patients who experienced a discordant response to PRRT (responder vs. non-responder) according to RECIST1.1. The patients presented with liver metastasis from the rectum and pancreas G3-NET, respectively. Whole-body total-lesion somatostatin receptor-expression (TLSREwb-50) and somatostatin receptor-expressing tumor volume (SRETV wb-50) were obtained in pre- and post-PRRT PET/CT. Radiomic analysis was performed, extracting 38 radiomic features (RFs) from the patients' lesions. The Mann–Whitney test was used to compare RFs in the responder patient vs. the non-responder patient. Pearson correlation and principal component analysis (PCA) were used to evaluate the correlation and independence of the different RFs. Results: TLSREwb-50 and SRETVwb-50 modifications correlate with RECIST1.1 response. A total of 28 RFs extracted on pre-therapy PET/CT showed significant differences between the two patients in the Mann–Whitney test (p < 0.05). A total of seven second-order features, with poor correlation with SUVmax and PET volume, were identified by the Pearson correlation matrix. Finally, the first two PCA principal components explain 83.8% of total variance. Conclusion: TLSREwb-50 and SRETVwb-50 are parameters that might be used to predict and to assess the PET response to PRRT. RFs might have a role in defining inter-patient heterogeneity and in the prediction of therapy response. It is important to implement future studies with larger and more homogeneous patient populations to confirm the efficacy of these biomarkers.
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DNA damage in lens epithelial cells exposed to occupationally-relevant X-ray doses and role in cataract formation. Sci Rep 2020; 10:21693. [PMID: 33303795 PMCID: PMC7728785 DOI: 10.1038/s41598-020-78383-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 10/28/2020] [Indexed: 11/09/2022] Open
Abstract
The current framework of radiological protection of occupational exposed medical workers reduced the eye-lens equivalent dose limit from 150 to 20 mSv per year requiring an accurate dosimetric evaluation and an increase understanding of radiation induced effects on Lens cells considering the typical scenario of occupational exposed medical operators. Indeed, it is widely accepted that genomic damage of Lens epithelial cells (LEC) is a key mechanism of cataractogenesis. However, the relationship between apoptosis and cataractogenesis is still controversial. In this study biological and physical data are combined to improve the understanding of radiation induced effects on LEC. To characterize the occupational exposure of medical workers during angiographic procedures an INNOVA 4100 (General Electric Healthcare) equipment was used (scenario A). Additional experiments were conducted using a research tube (scenario B). For both scenarios, the frequencies of binucleated cells, micronuclei, p21-positive cells were assessed with different doses and dose rates. A Monte-Carlo study was conducted using a model for the photon generation with the X-ray tubes and with the Petri dishes considering the two different scenarios (A and B) to reproduce the experimental conditions and validate the irradiation setups to the cells. The simulation results have been tallied using the Monte Carlo code MCNP6. The spectral characteristics of the different X-ray beams have been estimated. All irradiated samples showed frequencies of micronuclei and p21-positive cells higher than the unirradiated controls. Differences in frequencies increased with the delivered dose measured with Gafchromic films XR-RV3. The spectrum incident on eye lens and Petri, as estimated with MCNP6, was in good agreement in the scenario A (confirming the experimental setup), while the mean energy spectrum was higher in the scenario B. Nevertheless, the response of LEC seemed mainly related to the measured absorbed dose. No effects on viability were detected. Our results support the hypothesis that apoptosis is not responsible for cataract induced by low doses of X-ray (i.e. 25 mGy) while the induction of transient p21 may interfere with the disassembly of the nuclear envelop in differentiating LEC, leading to cataract formation. Further studies are needed to better clarify the relationship we suggested between DNA damage, transient p21 induction and the inability of LEC enucleation.
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Radiomics Analysis of Stereotactic Body Radiation Therapy Patients with Lung Cancer as a Toxicity Biomarker. Int J Radiat Oncol Biol Phys 2020. [DOI: 10.1016/j.ijrobp.2020.07.1338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Uncertainty analysis of tumour absorbed dose calculations in molecular radiotherapy. EJNMMI Phys 2020; 7:63. [PMID: 33044651 PMCID: PMC7550507 DOI: 10.1186/s40658-020-00328-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 09/16/2020] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Internal dosimetry evaluation consists of a multi-step process ranging from imaging acquisition to absorbed dose calculations. Assessment of uncertainty is complicated and, for that reason, it is commonly ignored in clinical routine. However, it is essential for adequate interpretation of the results. Recently, the EANM published a practical guidance on uncertainty analysis for molecular radiotherapy based on the application of the law of propagation of uncertainty. In this study, we investigated the overall uncertainty on a sample of a patient following the EANM guidelines. The aim of this study was to provide an indication of the typical uncertainties that may be expected from performing dosimetry, to determine parameters that have the greatest effect on the accuracy of calculations and to consider the potential improvements that could be made if these effects were reduced. RESULTS Absorbed doses and the relative uncertainties were calculated for a sample of 49 patients and a total of 154 tumours. A wide range of relative absorbed dose uncertainty values was observed (14-102%). Uncertainties associated with each quantity along the absorbed dose calculation chain (i.e. volume, recovery coefficient, calibration factor, activity, time-activity curve fitting, time-integrated activity and absorbed dose) were estimated. An equation was derived to describe the relationship between the uncertainty in the absorbed dose and the volume. The largest source of error was the VOI delineation. By postulating different values of FWHM, the impact of the imaging system spatial resolution on the uncertainties was investigated. DISCUSSION To the best of our knowledge, this is the first analysis of uncertainty in molecular radiotherapy based on a cohort of clinical cases. Wide inter-lesion variability of absorbed dose uncertainty was observed. Hence, a proper assessment of the uncertainties associated with the calculations should be considered as a basic scientific standard. A model for a quick estimate of uncertainty without implementing the entire error propagation schema, which may be useful in clinical practice, was presented. Ameliorating spatial resolution may be in future the key factor for accurate absorbed dose assessment.
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Abstract
Purpose Currently, no consistent guidelines for CT scans used within PET/CT examinations are available. This systematic review provides an up-to-date overview of studies to answer the following questions: What are the specific CT protocols used in PET/CT? What are the possible purposes of requiring a CT study within a PET/CT scan? Is the CT protocol obtained from a dosimetric optimisation study? Materials and method PubMed/MEDLINE, Cochrane Library, Embase and Scopus were systematically searched for relevant studies in accordance with the PRISMA statement. The literature search was conducted from January 2007 until June 2019. Data derived from studies were standardized in order to reduce possible biases, and they were divided into clinically homogeneous subgroups (adult, child or phantom). Subsequently, we divided the CT protocol intents into 3 types (anatomic localization only, attenuation correction only and diagnostic purpose). A narrative approach was used to summarise datasets and to investigate their heterogeneity (due to medical prescription methodology) and their combination in multiseries CT protocols. When weighted computed tomography dose index (CTDIw) was available, we calculated the volumetric computed tomography dose index (CTDIvol) using the pitch value to make the results uniform. Eventually, the correlation between protocol intents and CTDIvol values was obtained using a Kruskal–Wallis one-way ANOVA statistical test. Result Starting from a total of 1440 retrieved records, twenty-four studies were eligible for inclusion in addition to two large multicentric works that we used to compare the results. We analyzed 87 CT protocols. There was a considerable range of variation in the acquisition parameters: tube current–time product revealed to have the most variable range, which was 10–300 mAs for adults and 10–80 mAs for paediatric patients. Seventy percent of datasets presented scans acquired with tube current modulation, 9% used fixed tube current and in 21% of them, this information was not available. Dependence between mean CTDIvol values and protocol intent was statistically significant (p = 0.002). As expected, in diagnostic protocols, there was a statistically significant difference between CTDIvol values of with and without contrast acquisitions (11.68 mGy vs 7.99 mGy, p = 0.009). In 13 out of 87 studies, the optimisation aim was not reported; in 2 papers, a clinical protocol was used; and in 11 works, a dose optimisation protocol was applied. Conclusions According to this review, the dose optimisation in PET/CT exams depends heavily on the correct implementation of the CT protocol. In addition to this, considering the latest technology advances (i.e. iterative algorithms development), we suggest a periodic quality control audit to stay updated on new clinical utility modalities and to achieve a shared standardisation of clinical protocols. In conclusion, this study pointed out the necessity to better identify the specific CT protocol use within PET/CT scans, taking into account the continuous development of new technologies.
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Texture analysis and multiple-instance learning for the classification of malignant lymphomas. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2020; 185:105153. [PMID: 31678792 DOI: 10.1016/j.cmpb.2019.105153] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 10/16/2019] [Accepted: 10/23/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND AND OBJECTIVES Malignant lymphomas are cancers of the immune system and are characterized by enlarged lymph nodes that typically spread across many different sites. Many different histological subtypes exist, whose diagnosis is typically based on sampling (biopsy) of a single tumor site, whereas total body examinations with computed tomography and positron emission tomography, though not diagnostic, are able to provide a comprehensive picture of the patient. In this work, we exploit a data-driven approach based on multiple-instance learning algorithms and texture analysis features extracted from positron emission tomography, to predict differential diagnosis of the main malignant lymphomas subtypes. METHODS We exploit a multiple-instance learning setting where support vector machines and random forests are used as classifiers both at the level of single VOIs (instances) and at the level of patients (bags). We present results on two datasets comprising patients that suffer from four different types of malignant lymphomas, namely diffuse large B cell lymphoma, follicular lymphoma, Hodgkin's lymphoma, and mantle cell lymphoma. RESULTS Despite the complexity of the task, experimental results show that, with sufficient data samples, some cancer subtypes, such as the Hodgkin's lymphoma, can be identified from texture information: in particular, we achieve a 97.0% of sensitivity (recall) and a 94.1% of predictive positive value (precision) on a dataset that consists in 60 patients. CONCLUSIONS The presented study indicates that texture analysis features extracted from positron emission tomography, combined with multiple-instance machine learning algorithms, can be discriminating for different malignant lymphomas subtypes.
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Radiotherapy Planning and Molecular Imaging in Lung Cancer. Curr Radiopharm 2020; 13:204-217. [PMID: 32186275 PMCID: PMC8206193 DOI: 10.2174/1874471013666200318144154] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 03/11/2019] [Accepted: 11/11/2019] [Indexed: 12/24/2022]
Abstract
INTRODUCTION In patients suitable for radical chemoradiotherapy for lung cancer, 18F-FDGPET/ CT is a proposed management to improve the accuracy of high dose radiotherapy. However, there is a high rate of locoregional failure in patients with locally advanced non-small cell lung cancer (NSCLC), probably due to the fact that standard dosing may not be effective in all patients. The aim of the present review was to address some criticisms associated with the radiotherapy image-guided in NSCLC. MATERIALS AND METHODS A systematic literature search was conducted. Only published articles that met the following criteria were included: articles, only original papers, radiopharmaceutical ([18F]FDG and any tracer other than [18F]FDG), target, only specific for lung cancer radiotherapy planning, and experimental design (eventually "in vitro" studies were excluded). Peer-reviewed indexed journals, regardless of publication status (published, ahead of print, in press, etc.) were included. Reviews, case reports, abstracts, editorials, poster presentations, and publications in languages other than English were excluded. The decision to include or exclude an article was made by consensus and any disagreement was resolved through discussion. RESULTS Hundred eligible full-text articles were assessed. Diverse information is now available in the literature about the role of FDG and new alternative radiopharmaceuticals for the planning of radiotherapy in NSCLC. In particular, the role of alternative technologies for the segmentation of FDG uptake is essential, although indeterminate for RT planning. The pros and cons of the available techniques have been extensively reported. CONCLUSION PET/CT has a central place in the planning of radiotherapy for lung cancer and, in particular, for NSCLC assuming a substantial role in the delineation of tumor volume. The development of new radiopharmaceuticals can help overcome the problems related to the disadvantage of FDG to accumulate also in activated inflammatory cells, thus improving tumor characterization and providing new prognostic biomarkers.
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Partial volume effect of SPECT images in PRRT with 177Lu labelled somatostatin analogues: A practical solution. Phys Med 2019; 57:153-159. [PMID: 30738519 DOI: 10.1016/j.ejmp.2018.12.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 11/26/2018] [Accepted: 12/20/2018] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND At present activity quantification is one of the most critical step in dosimetry calculation, and Partial Volume Effect (PVE) one of the most important source of error. In recent years models based upon phantoms that incorporate hot spheres have been used to establish recovery models. In this context the goal of this study was to point out the most critical issues related to PVE and to establish a model closer to a biological imaging environment. METHODS Two different phantoms, filled with a 177Lu solution, were used to obtain the PVE Recovery Coefficients (RCs): a phantom with spherical inserts and a phantom with organ-shaped inserts. Two additional phantoms with inserts of various geometrical shapes and an anthropomorphic phantom were acquired to compare the real activities to predicted values after PVE correction. RESULTS The RCs versus volume of the inserts produced two different curves, one for the spheres and one for the organs. After PVE correction, accuracy on activity quantification averaged over all inserts of three test phantoms passed from -26% to 1.3% (from 26% to 10% for absolute values). CONCLUSION RCs is a simple method for PVE correction easily applicable in clinical routine. The use of two different models for organs and lesions has permitted to closely mimic the situation in a living subject. A marked improvement in the quantification of activity was observed when PVE correction was adopted, even if further investigations should be performed for more accurate models of PVE corrections.
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142. DoseFX: A software for dosimetry of organs and lesions in molecular radiotherapy. Phys Med 2018. [DOI: 10.1016/j.ejmp.2018.04.153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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[OA169] Advanced personalised 3D dosimetry for peptide receptor radionuclide therapy based on monte carlo method. Phys Med 2018. [DOI: 10.1016/j.ejmp.2018.06.241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Effect of image registration on 3D absorbed dose calculations in 177 Lu-DOTATOC peptide receptor radionuclide therapy. Phys Med 2018; 45:177-185. [DOI: 10.1016/j.ejmp.2017.11.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 10/18/2017] [Accepted: 11/26/2017] [Indexed: 11/29/2022] Open
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Abstract ID: 160 Advanced personalised 3D dosimetry based on Monte Carlo simulation for Peptide Receptor Radionuclide Therapy. Phys Med 2017. [DOI: 10.1016/j.ejmp.2017.09.084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Added diagnostic value of respiratory-gated 4D 18F-FDG PET/CT in the detection of liver lesions: a multicenter study. Eur J Nucl Med Mol Imaging 2017; 45:102-109. [PMID: 28825125 DOI: 10.1007/s00259-017-3795-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 07/26/2017] [Indexed: 11/30/2022]
Abstract
PURPOSE The aim of the present study was to evaluate the added diagnostic value of respiratory-gated 4D18F-FDG PET/CT in liver lesion detection and characterization in a European multicenter retrospective study. METHODS Fifty-six oncological patients (29 males and 27 females, mean age, 61.2 ± 11.2 years) from five European centers, submitted to standard 3D-PET/CT and liver 4D-PET/CT were retrospectively evaluated. Based on visual analysis, liver PET/CT findings were scored as positive, negative, or equivocal both in 3D and 4D PET/CT. The impact of 4D-PET/CT on the confidence in classifying liver lesions was assessed. PET/CT findings were compared to histology and clinical follow-up as standard reference and diagnostic accuracy was calculated for both techniques. At semi-quantitative analysis, SUVmax was calculated for each detected lesion in 3D and 4D-PET/CT. RESULTS Overall, 72 liver lesions were considered for the analysis. Based on visual analysis in 3D-PET/CT, 32/72 (44.4%) lesions were considered positive, 21/72 (29.2%) negative, and 19/72 (26.4%) equivocal, while in 4D-PET/CT 48/72 (66.7%) lesions were defined positive, 23/72 (31.9%) negative, and 1/72 (1.4%) equivocal. 4D-PET/CT findings increased the confidence in lesion definition in 37/72 lesions (51.4%). Considering 3D equivocal lesions as positive, sensitivity, specificity, and accuracy were 88.9, 70.0, and 83.1%, respectively, while the same figures were 67.7, 90.0, and 73.8% if 3D equivocal findings were included as negative. 4D-PET/CT sensitivity, specificity, and accuracy were 97.8, 90.0, and 95.4%, respectively, considering equivocal lesions as positive and 95.6, 90.0, and 93.8% considering equivocal lesions as negative. The SUVmax of the liver lesions in 4D-PET (mean ± SD, 6.9 ± 3.2) was significantly higher (p < 0.001) than SUVmax in 3D-PET (mean ± SD, 5.2 ± 2.3). CONCLUSIONS Respiratory-gated PET/CT technique is a valuable clinical tool in diagnosing liver lesions, reducing 3D undetermined findings, improving diagnostic accuracy, and confidence in reporting. 4D-PET/CT also improved the quantification of SUVmax of liver lesions.
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18F-fluorodeoxyglucose positron emission tomographic scan in solid-type p-stage-I pulmonary adenocarcinomas: what can produce false-negative results?†. Eur J Cardiothorac Surg 2017:ezw394. [DOI: 10.1093/ejcts/ezw394] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 08/29/2023] Open
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The Italian multicentre dosimetric study for lesion dosimetry in 223 Ra therapy of bone metastases: Calibration protocol of gamma cameras and patient eligibility criteria. Phys Med 2016; 32:1731-1737. [DOI: 10.1016/j.ejmp.2016.09.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 08/29/2016] [Accepted: 09/16/2016] [Indexed: 10/21/2022] Open
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F-03718-F FDG PET/CT SCAN IN SOLID-TYPE STAGE-I PULMONARY ADENOCARCINOMAS: WHAT CAUSES FALSE-NEGATIVE CASES? Interact Cardiovasc Thorac Surg 2016. [DOI: 10.1093/icvts/ivw260.37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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The 68 Ge phantom-based FDG-PET site qualification program for clinical trials adopted by FIL (Italian Foundation on Lymphoma). Phys Med 2016; 32:651-6. [DOI: 10.1016/j.ejmp.2016.04.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 03/10/2016] [Accepted: 04/13/2016] [Indexed: 01/01/2023] Open
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EP-1864: A 18FDG-PET texture analysis study on early stage Hodgkin Lymphoma patient outcome prediction. Radiother Oncol 2016. [DOI: 10.1016/s0167-8140(16)33115-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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PET scanner clinical trial qualification with 68Ge-filled NEMA/IEC image quality phantom outperforms with respect to 18F. Phys Med 2016. [DOI: 10.1016/j.ejmp.2016.01.350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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A multicenter dosimetric and observational study for lesion dosimetry in 223Ra therapy of bone metastases: Calibration protocol and eligibility criteria. Phys Med 2016. [DOI: 10.1016/j.ejmp.2016.01.378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Therapeutic schemes in 177Lu and 90Y-PRRT: radiobiological considerations. THE QUARTERLY JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING : OFFICIAL PUBLICATION OF THE ITALIAN ASSOCIATION OF NUCLEAR MEDICINE (AIMN) [AND] THE INTERNATIONAL ASSOCIATION OF RADIOPHARMACOLOGY (IAR), [AND] SECTION OF THE SOCIETY OF RADIOPHARMACEUTICAL CHEMISTRY AND BIOLOGY 2015; 61:216-231. [PMID: 26576734 DOI: 10.23736/s1824-4785.16.02744-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND The purpose of this work is to implement a radiobiological model to compare different treatment schedules for Peptide Receptor Radionuclide Therapy (PRRT) with 177Lu and 90Y. The principal radiobiological quantities were studied as a function of radionuclides, fractionation schemes, activity distribution in kidneys and tumor radiosensitivity. METHODS Clinical data were used to derive representative absorbed doses for several treatment schemes for 177Lu-PRRT and for 90Y-PRRT and considered as input data for the radiobiological model. Both uniform and non-uniform activity distributions were considered for kidneys and cortex; for tumors a possible uptake reduction after each cycle and inter-patient radiosensitivity variability were investigated. Normal-Tissue-Complication-Probability (NTCP) and Tumor-Control-Probability (TCP) were evaluated. RESULTS Hyper-cycling has a limited advantage in terms of BED reduction on kidneys for 177Lu, while for 90Y the effect is sizable and helps in reducing the NTCP. For all 177Lu-schemes the renal toxicity risk is negligible while for some 90Y-schemes the NTCP is not null. In case of tumor uptake reduction with cycles the treatment efficacy is reduced with a BED loss up to 46%. The TCP decreases when assuming normally-distributed tumor radiosensitivity values. CONCLUSIONS This paper discusses how the combination of dosimetry and radiobiological modeling may help in exploring the link between the treatment schedule and the potential clinical outcome. The results highlight the capability of model to reproduce the available clinical data and provide useful qualitative information. Further investigation on dose distribution and dose uptake reduction with accurate clinical data is needed to progress in this field.
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Time Evolution of DOTATOC Uptake in Neuroendocrine Tumors in View of a Possible Application of Radioguided Surgery with β− Decay. J Nucl Med 2015; 56:1501-6. [DOI: 10.2967/jnumed.115.160481] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 07/13/2015] [Indexed: 11/16/2022] Open
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PO-0894: Patient specific 3D dose calculation for 177Lu treatment of neuroendocrine tumours using the Raydose MC code. Radiother Oncol 2015. [DOI: 10.1016/s0167-8140(15)40886-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Quantitative comparison between the commercial software STRATOS(®) by Philips and a homemade software for voxel-dosimetry in radiopeptide therapy. Phys Med 2014; 31:72-9. [PMID: 25457430 DOI: 10.1016/j.ejmp.2014.10.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 10/02/2014] [Accepted: 10/05/2014] [Indexed: 10/24/2022] Open
Abstract
BACKGROUND Targeted radionuclide therapy is a rapidly growing modality. A few commercial treatment planning systems are entering the market. However, some in-house systems are currently developed for a more flexible and customized dosimetry calculation at voxel-level. For this purpose, we developed a novel software, VoxelMed, and performed a comparison with the software STRATOS. METHODS The validation of both of them was undertaken using radioactive phantoms with different volume inserts. A cohort of 10 patients was also studied after a therapeutic administration of (177)Lu-labelled radiopeptides. The activity, number of disintegrations, absorbed dose and dose-volume histogram (DVH) were calculated for the phantoms and the kidneys in patients, which were the main critical organs at risk in this study. RESULTS In phantoms the absorbed doses computed with VoxelMed and STRATOS agree within 5%. In patients at the voxel-level the absorbed dose to kidneys (VoxelMed: mean 0.66 Gy/GBq) showed a limited difference of 5%, but with a remarkable range (-40%, +60%) between the two software packages. Voxel-dosimetry allows to estimate the dose non-homogeneities in volumes, which may be evaluated through DVHs. CONCLUSION This study demonstrates that a fully 3D voxel-dosimetry with multiple SPECT images is feasible by using home-made or commercial software package and absorbed dose results obtained are similar. The main difference between the studied tools was observed in the activity integration method (effective vs physical half-time to time activity curve tail). We believe that an effective half-time integration method produces a more accurate approximation of clinical uptake and resultant dosimetry.
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Differentiated thyroid cancer: a new perspective with radiolabeled somatostatin analogues for imaging and treatment of patients. Thyroid 2014; 24:715-26. [PMID: 24102584 DOI: 10.1089/thy.2013.0225] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
BACKGROUND The expression of somatostatin receptors (SSTR) in thyroid cells may offer the possibility to identify metastatic lesions and to select patients for peptide receptor radionuclide therapy (PRRT). We investigated (68)Ga-DOTATOC positron emission tomography/computed tomography (PET/CT) to select patients with progressive differentiated thyroid cancer (DTC) for PRRT as well as treatment response and toxicity in treated patients. METHODS We enrolled 41 patients with progressive radioiodine-negative DTC (24 women and 17 men; mean age=54.3 years, median=59 years, range=19-78 years). In all patients, [(18)F]FDG-PET/CT was performed to determine recurrent disease with enhanced glucose metabolism, and (68)Ga-DOTATOC PET/CT was used to identify SSTR expression. Dosimetric evaluation was performed with (111)In-DOTATOC scintigraphy. Eleven patients were treated with PRRT receiving a fractionated injection of 1.5-3.7 GBq (90)Y-DOTATOC/administration. Serial (68)Ga-DOTATOC PET/CT scans were performed in all treated patients to evaluate treatment response. Parameters provided by (68)Ga-DOTATOC PET/CT were analyzed as potential therapeutic predictors to differentiate responding from nonresponding. In all treated patients, adverse events and toxicity were recorded. RESULTS (68)Ga-DOTATOC PET/CT were positive in 24/41 of radioiodine-negative DTC patients. Based on the high expression of SSTR detected by (68)Ga-DOTATOC PET/CT, 13 patients were suitable for PRRT. Two out of 13 patients were not treated due to the lack of fulfillment of other study inclusion criteria. PRRT induced disease control in 7/11 patients (two partial response and five stabilization) with a duration of response of 3.5-11.5 months. Objective response was associated with symptoms relief. Functional volume (FV) over time obtained by PET/CT was the only parameter demonstrating a significant difference between lesions responding and nonresponding to PRRT (p=0.001). Main PRRT adverse events were nausea, asthenia, and transient hematologic toxicity. One patient experienced permanent renal toxicity. CONCLUSIONS In our series, SSTR imaging provided positive results in more than half of the cases with radioiodine-negative DTC, and about one third of patients were eligible for PRRT. (68)Ga-DOTATOC PET/CT seems a reliable tool both for patient selection and evaluation of treatment response. In our experience, FV determination over time seems to represent a reliable parameter to determine tumor response to PRRT, although further investigations are needed to better define its role.
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Radiation protection procedures in 131I treatments for thyroid cancer in patients requiring hemodialysis. Nucl Med Commun 2014; 35:626-30. [PMID: 24584218 DOI: 10.1097/mnm.0000000000000095] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Hemodialysis is essential for patients with renal failure, and iodine-131 ((131)I) administration is the standard of care in thyroid carcinoma treatment. Although the need for hemodialysis during (131)I treatment is very rare, it raises some concerns due to the involvement of personnel not exposed to radiation and to the contamination of devices used for other patients. In this paper, a radioprotection protocol to perform hemodialysis safely on patients during (131)I treatment has been presented. PATIENTS AND METHODS The exposure of personnel who assisted 13 patients over the course of 10 years was monitored: external exposure was measured through electronic dosimeters, and internal contamination was checked by thyroid uptake and urine sample gamma spectrometry. Over this period, room layout was optimized to allow an improvement of radioprotection procedures.Two nurses were involved in patient assistance. RESULTS After hemodialysis, measurements of internal contamination were below the minimum detectable activity and external exposure was in the range of 1-82 μSv in terms of H(p)(10). A reduction in personnel exposure was observed after hospitalization room renovation: H(p)(10) normalized to the activity administered to the patient was about halved. CONCLUSION The data show that hemodialysis can be performed safely during I treatments when appropriate radioprotection actions are implemented.
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Metabolic tumour volumes measured at staging in lymphoma: methodological evaluation on phantom experiments and patients. Eur J Nucl Med Mol Imaging 2014; 41:1113-22. [DOI: 10.1007/s00259-014-2705-y] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 01/16/2014] [Indexed: 10/25/2022]
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Respiratory gated PET/CT in a European multicentre retrospective study: added diagnostic value in detection and characterization of lung lesions. Eur J Nucl Med Mol Imaging 2012; 39:1381-90. [PMID: 22588628 DOI: 10.1007/s00259-012-2148-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 04/24/2012] [Indexed: 02/05/2023]
Abstract
PURPOSE The aim of our work is to evaluate the added diagnostic value of respiratory gated (4-D) positron emission tomography/computed tomography (PET/CT) in lung lesion detection/characterization in a large patient population of a multicentre retrospective study. METHODS The data of 155 patients (89 men, 66 women, mean age 63.9 ± 11.1 years) from 5 European centres and submitted to standard (3-D) and 4-D PET/CT were retrospectively analysed. Overall, 206 lung lesions were considered for the analysis (mean ± SD lesions dimension 14.7 ± 11.8 mm). Maximum standardized uptake values (SUV(max)) and lesion detectability were assessed for both 3-D and 4-D PET/CT studies; 3-D and 4-D PET/CT findings were compared to clinical follow-up as standard reference. RESULTS Mean ± SD 3-D and 4-D SUV(max) values were 5.2 ± 5.1 and 6.8 ± 6.1 (p < 0.0001), respectively, with an average percentage increase of 30.8 %. In 3-D PET/CT, 86 of 206 (41.7 %) lesions were considered positive, 70 of 206 (34 %) negative and 50 of 206 (24.3 %) equivocal, while in 4-D PET/CT 117 of 206 (56.8 %) lesions were defined as positive, 80 of 206 (38.8 %) negative and 9 of 206 (4.4 %) equivocal. In 34 of 50 (68 %) 3-D equivocal lesions follow-up data were available and the presence of malignancy was confirmed in 21 of 34 (61.8 %) lesions, while in 13 of 34 (38.2 %) was excluded. In 31 of these 34 controlled lesions, 20 of 34 (58.8 %) and 11 of 34 (32.4 %) were correctly classified by 4-D PET/CT as positive and negative, respectively; 3 of 34 (8.8 %) remained equivocal. With equivocal lesions classified as positive, the overall accuracy of 3-D and 4-D was 85.7 and 92.8 %, respectively, while the same figures were 80.5 and 94.2 % when equivocal lesions were classified as negative. CONCLUSION The respiratory gated PET/CT technique is a valuable clinical tool in diagnosing lung lesions, improving quantification and confidence in reporting, reducing 3-D undetermined findings and increasing the overall accuracy in lung lesion detection and characterization.
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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. HEALTH PHYSICS 2011; 100:515-522. [PMID: 21451322 DOI: 10.1097/hp.0b013e3182092732] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
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.
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PET/CT and radiotherapy : data transfer, radiotherapy workflow and quality assurance. THE QUARTERLY JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING : OFFICIAL PUBLICATION OF THE ITALIAN ASSOCIATION OF NUCLEAR MEDICINE (AIMN) [AND] THE INTERNATIONAL ASSOCIATION OF RADIOPHARMACOLOGY (IAR), [AND] SECTION OF THE SOCIETY OF... 2010; 54:476-489. [PMID: 20927015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The development of new technologies in radiation therapy has made it possible to introduce more sophisticated techniques that can deliver the prescribed dose with more conformation and accuracy and to apply dose escalation protocols without increasing the risk of healthy tissue damage. This has consented the simultaneous delivery of different dose levels to different parts of the target, making it possible to boost those tumour sub-volumes that are considered more radio resistant. The use of PET for radiotherapy planning purposes has become increasingly important in the last few years, because of its ability to provide valuable biologic and functional data. PET imaging can affect the treatment strategy definition and improve the target delineation and the assessment of therapy response. The most attractive aspect is the perspective to deliver differential doses inside target volumes for areas of different biologic behaviour based on functional imaging, moving closer to the goals of biologically conformal radiation therapy. Each single step of PET/CT-guided radiotherapy workflow, needs to be performed following high standard procedures, within a rigorous and appropriate quality assurance protocol to minimize the sources of errors and to maximize the efficacy of PET imaging in radiation therapy, ensuring safe and effective use of the technology. The present paper focuses on aspects concerning the use of PET/CT in radiation treatment process, with the aim to delineate different possible approaches to its clinical application and to highlight the critical aspects of the various subprocesses.
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85 poster: 4D PET/CT Valutation on Integration and Impact in Radiation Therapy Planning of Lung Tumor. Radiother Oncol 2010. [DOI: 10.1016/s0167-8140(15)34504-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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63 poster: Comparison Between 18F-Choline Uptake and Choline Detection in MR Spectroscopy in One Case of Brain Tumour. Radiother Oncol 2010. [DOI: 10.1016/s0167-8140(10)80012-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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4D-PET data sorting into different number of phases: a NEMA IQ phantom study. J Appl Clin Med Phys 2009; 10:220-231. [PMID: 19918221 PMCID: PMC5720569 DOI: 10.1120/jacmp.v10i4.2917] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Revised: 05/15/2009] [Accepted: 05/13/2009] [Indexed: 11/25/2022] Open
Abstract
This study aims to evaluate the dependence of 4D‐PET data sorting on the number of phases in which the respiratory cycle can be divided. The issue is to find the best compromise to reduce the conflicting effects induced by increasing the number of phases: lesion motion on each set of images decreases, but on the other hand image noise increases. The IQ NEMA 2001 IEC body phantom was used to simulate the movement of neoplastic lesions in the thorax and abdomen, investigating the effect of: target size (10 37 mm), lesion‐to‐background activity concentration ratio (4:1 and 8:1), total acquisition time (3, 6, 12, 20 min), and number of phase partitions (1, 2, 4, 6, 8, 10, 13). The phantom was moved in a cranial‐caudal direction with an excursion of 25 mm and a period of 4.0 sec. Five parameters associated to lesion volume and activity concentration were considered to assess the capability of the 4D‐PET technique to “freeze” the phantom motion. The results for all the parameters showed the capability of the 4D‐PET acquisition technique to “freeze” the lesion motion. The division into six phases was found to be the best compromise between temporal resolution and image noise for the phase where the “lesions” move faster; whereas the partition into four phases could be used if a stable breathing phase is considered. PACS number: 87.57.uk; 87.57.cp
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Use of Positron Emission Tomography for Target Volume Definition. Curr Radiopharm 2009. [DOI: 10.2174/1874471010902030144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Validation of (68)Ge/(68)Ga generator processing by chemical purification for routine clinical application of (68)Ga-DOTATOC. Nucl Med Biol 2008; 35:721-4. [PMID: 18678358 DOI: 10.1016/j.nucmedbio.2008.04.006] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2007] [Revised: 04/17/2008] [Accepted: 04/23/2008] [Indexed: 01/08/2023]
Abstract
INTRODUCTION Imaging of somatostatin receptor expressing tumours has been greatly enhanced by the use of (68)Ga-DOTATOC and PET/CT. METHODS In this work, a purification method for the (68)Ge/(68)Ga generator eluate and a method to produce (68)Ga-DOTATOC suitable for clinical use were evaluated. The generator eluate was purified and concentrated on a cation-exchange cartridge in HCl/acetone media. The efficacy of this procedure in eliminating metal impurities from the (68)Ga solution was investigated by ICP-MS. The radiotracer quality was evaluated by radio-TLC, GC and gamma-ray spectrometry. RESULTS (68)Ga-DOTATOC preparations (n=33) were carried out with a mean synthesis yield of 59.3+/-2.8% (not corrected for decay) and a batch activity ranging from 555 to 296 MBq. The radiochemical and radionuclidic purity were >98% and 99.9999%, respectively. With this purification process, >95% of the Fe(III), Zn(II) and Mn(II) were eliminated from the solution. CONCLUSIONS (68)Ga-DOTATOC produced with this method can be efficiently used in nuclear medicine departments for PET evaluations.
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Purification by ozonolysis of 18O enriched water after cyclotron irradiation and the utilization of the purified water for the production of [18F]-FDG (2-deoxy-2-[18F]-fluoro-d-glucose). Appl Radiat Isot 2007; 65:831-5. [PMID: 17459713 DOI: 10.1016/j.apradiso.2007.03.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2006] [Revised: 03/06/2007] [Accepted: 03/08/2007] [Indexed: 11/15/2022]
Abstract
The high cost of virgin (18)O-enriched water has forced many researchers to study methods to purify and recycle enriched water after the first irradiation for the production of radiopharmaceuticals. In our study, [(18)O]H(2)O was purified by ozonolysis and distillation. Analyses showed a large decrease in impurities after this treatment. The purification procedure was carried out after the production of 94 batches of [18F]-FDG, which were manufactured using a GE Minitrace cyclotron and a GE Mx TracerLab synthesizer. Saturation yields after bombardment, using virgin and re-purified water were, respectively, 2864+/-204MBq/muA and 2727+/-167MBq/muA, a decrease of 5.5%. The decrease in [18F]-FDG yield, from 67.2+/-0.7% to 65.5+/-0.9%, can be ascribed to the irradiation step only.
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Abstract
Single doses of triphenyl phosphite (TPP), a triester of trivalent phosphorus, cause ataxia and paralysis in hens. Characteristics of neurotoxicity were described as somewhat different from organophosphate induced delayed polyneuropathy (OPIDP), which is caused by triesters of pentavalent phosphorus. The onset of TPP neuropathy was reported to occur earlier than that of OPIDP (5-10 versus 7-14 days after dosing, respectively), and chromatolysis, neuronal necrosis and lesions in certain areas of the brain were found in TPP neuropathy only. Pretreatment with phenylmethanesulfonyl fluoride (PMSF) protects from OPIDP, but it either partially protected from effects of low doses or exacerbated those of higher doses of TPP. In order to account for these differences with OPIDP, it was suggested that TPP neuropathy results from the combination of two independent mechanisms of toxicity: typical OPIDP due to inhibition of neuropathy target esterase (NTE) plus a second neurotoxicity related with other target(s). We explored TPP neuropathy in the hen with attention to the phenomena of promotion and protection which are both caused by PMSF when given in combination with typical neuropathic OPs. When PMSF is given before neuropathic OPs it protects from OPIDP; when given afterwards it exaggerates OPIDP. The former effect is due to interactions with NTE, the latter to interactions with an unknown site. The time course of NTE reappearance after TPP (60 or 90 mg/kg i.v.) inhibition showed a longer half-life when compared to that after PMSF (30 mg/kg s.c.) (10-15 versus 4-6 days, respectively). The clinical signs of TPP neuropathy (60 or 90 mg/kg i.v.) were similar to those observed in OPIDP, appeared 7-12 days after treatment, correlated with more than 70% NTE inhibition/aging and were preceded by a reduction of retrograde axonal transport in sciatic nerve of hens. TPP (60 mg/kg i.v.) neuropathy was promoted by PMSF (120 mg/kg s.c.) given up to 12 days afterwards and was partially protected by PMSF (10-120 mg/kg s.c.) when given 24 h before TPP (60 or 90 mg/kg i.v.). The previously reported early onset of TPP neuropathy might be related to the higher dose used in those experiments and to the resulting more severe neuropathy. The lack of full protection might be explained by the slow kinetics of TPP, which would cause substantial NTE inhibition when PMSF effects on NTE had subsided. Since PMSF also affects the promotion site when given before initiation of neuropathy, the resulting neuropathy would then be due to both protection from and promotion of TPP effects by PMSF. No promotion by PMSF (120 mg/kg s.c.) was observed in TPP neuropathy (90 mg/kg i.v.) partially protected by PMSF (10-30 mg/kg s.c.). This might also be explained by the concurrent effects on NTE and on the promotion site obtained with PMSF pretreatment. We conclude that TPP neuropathy in the hen is likely to be the same as typical OPIDP. The unusual effects of combined treatment to hens with TPP and PMSF are explained by the prolonged pharmacokinetics of TPP and by the dual effect of PMSF i.e. protection from and promotion of OPIDP.
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Organophosphate polyneuropathy and neuropathy target esterase: studies with methamidophos and its resolved optical isomers. Arch Toxicol 1995; 69:330-6. [PMID: 7654138 DOI: 10.1007/s002040050179] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Methamidophos (O,S-dimethyl phosphorothioamidate) causes polyneuropathy in man and hens. However, experiments in the hen show that lower doses of methamidophos either protect from or promote the neuropathy caused by certain organophosphates. The initiation of neuropathy as well as protection from neuropathy are thought to be related to neuropathy target esterase (NTE), whereas promotion is likely to be due to interactions with another unknown target. Methamidophos is a racemate and we report studies with its resolved optical isomers, aimed at elucidating which isomer is responsible for the described effects. The time-course of acetylcholinesterase (AChE) and NTE activity in nervous tissues of hens after inhibition by single doses of either isomer showed that after D-(+) methamidophos (25 mg/kg PO) peak inhibition of both enzymes was achieved within 24 h (80-90%). However, after L-(-) methamidophos (15 mg/kg PO), peak inhibition (80-90%) was obtained within 24 h for AChE, whereas similar NTE inhibition (120 mg/kg PO) was observed only 4 days after dosing. The minimal neuropathic doses of D-(+) and L-(-) methamidophos were 60 and 120 mg/kg PO, respectively, and correlated with > 80% NTE inhibition in nervous tissues. OPIDP initiation by either isomer was slightly promoted by phenylmethanesulfonyl fluoride (120 mg/kg SC). D-(+) Methamidophos (25 mg/kg PO) partially protected from dibutyl dichlorovinyl-phosphate (DBDCVP) neuropathy (up to 0.8 mg/kg SC). This effect correlated with about 70% NTE inhibition. L-(-) Methamidophos (15 or 60 mg/kg PO) did not protect from DBDCVP neuropathy (0.2-0.8 mg/kg SC).
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