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[en] Introduction. - Radionuclide ventriculography provides a reproducible measurement of the left ventricular fraction ejection (LVEF) but with a significant body radiation (effective dose of 5,9 mSv for the injection of 850 MBq of 99mTc). The highly sensitive semi-conductor (CZT) cameras could allow decreasing the injected activity by a factor 3, similarly to that of myocardial perfusion imaging. Our study was aimed to determine whether the LVEF measurement provided by radionuclide ventriculography on the CZT D-SPECT camera is impacted by a 70% reduction in recorded counts. Materials and methods. - After the in vivo labeling of red blood cells with 850 MBq of 99mTc, 49 patients completed a conventional 2D recording (Conv-2D) on Anger camera followed by a 3D recording on the D-SPECT camera (3D-100%). The CZT recordings of all projections were subsequently shortened to 30% of their initial durations (3D-30%) in order to assess the LVEF measured with a 70% reduction in recorded counts. Results. - Mean LVEF values were 62.7±11.1% on Conv-2D and higher on both 3D-100% (66.8±14.8%, P < 0.001) and 3D-30% (66.3±15.7%, P < 0.001). The correlation coefficients with the LVEF determined with the reference Conv-2D method were equivalents for 3D-100% (r2 = 0.73) and 3D-30% (r2 = 0.70) and with a similar level of overestimation for the highest LEVF values. Conclusion. - A 70% reduction in recorded counts does not significantly impact the LVEF measured with radionuclide ventriculography on the CZT D-SPECT camera. These values are coherent with those obtained with the reference 2D method but with a clear overestimation for the highest LVEF values. (authors)
[fr]
Introduction. - La ventriculographie isotopique planaire mesure de facon reproductible la fraction d'ejection du ventricule gauche (FEVG) mais reste irradiante (5,9 mSv pour 850 MBq de 99mTc injectes). Les cameras a semi-conducteur (CZT), beaucoup plus sensibles, pourraient permettre de diminuer l'activite injectee au moins d'un facteur 3, comme en tomoscintigraphie myocardique. L'objectif de notre etude est de determiner si une diminution de 70 % de l'activite enregistree en ventriculographie isotopique sur la camera CZT D-SPECT impacte la mesure de la FEVG. Materiels et methodes. - Apres marquage in vivo des hematies avec 850 MBq de 99mTc, 49 patients ont realise un enregistrement conventionnel 2D (Conv-2D) sur camera d'Anger, suivi d'un enregistrement 3D sur camera CZT (3D-100 %). Les enregistrements CZT de toutes les projections ont ensuite ete reduits a 30 % de leurs durees d'acquisition initiale (3D-30 %) pour pouvoir evaluer la FEVG mesuree dans ces conditions de reduction d'activite. Resultats. - Les valeurs moyennes de FEVG etaient de 62,7±11,1 % en Conv-2D, mais plus elevees en 3D-100 % (66,8±14,8 %, p < 0,001) et 3D-30 % (66,3±15,7 %, p < 0,001). Les coefficients de correlation avec la methode Conv-2D de reference etaient equivalents en 3D-100 % (R2 = 0,73) et 3D-30 % (R2 = 0,70) et avec un meme degre de surestimation des FEVG les plus elevees. Conclusion. - Une diminution de 70 % de l'activite enregistree ne modifie pas significativement les valeurs de FEVG obtenues en ventriculo- graphie isotopique sur camera CZT D-SPECT. Ces valeurs restent coherentes avec celles obtenues avec la methode de reference 2D, mais avec pour l'instant l'inconvenient d'une surestimation pour les valeurs les plus elevees. (auteurs)Journal
Medecine Nucleaire. Imagerie Fonctionnelle et Metabolique; ISSN 0928-1258; 
; CODEN MNIMEX; v. 41(no.2); p. 83-92
; CODEN MNIMEX; v. 41(no.2); p. 83-92
[en] Random coincidences of events could be one of the main sources of background in the search for neutrino-less double-beta decay of Mo with macro-bolometers, due to their modest time resolution. Scintillating bolometers as those based on LiMoO crystals and employed in the CROSS and CUPID experiments can eventually exploit the coincident fast signal detected in a light detector to reduce this background. However, the scintillation provides a modest signal-to-noise ratio, making difficult a pile-up pulse-shape recognition and rejection at timescales shorter than a few ms. Neganov-Trofimov-Luke assisted light detectors (NTL-LDs) offer the possibility to effectively increase the signal-to-noise ratio, preserving a fast time-response, and enhance the capability of pile-up rejection via pulse shape analysis. In this article we present: (a) an experimental work performed with a LiMoO scintillating bolometer, studied in the framework of the CROSS experiment, and utilizing a NTL-LD; (b) a simulation method to reproduce, synthetically, randomly coincident two-neutrino double-beta decay events; (c) a new analysis method based on a pulse-shape discrimination algorithm capable of providing high pile-up rejection efficiencies. We finally show how the NTL-LDs offer a balanced solution between performance and complexity to reach background index ∼10 counts/keV/kg/year with 280 g LiMoO (Mo enriched) bolometers at 3034 keV, the Q of the double-beta decay, and target the goal of a next generation experiment like CUPID.
Journal
European Physical Journal. C, Particles and Fields (Online); ISSN 1434-6052; ; CODEN EPCFFB; v. 83(5); vp
; CODEN EPCFFB; v. 83(5); vp
[en] Introduction. - New gamma camera technology with Cadmium-Zinc-Telluride (CZT) semiconductor detectors provides better myocardial perfusion imaging (MPI) resolution and, given the detector's high-sensitivity (better spatial and energy resolution), it reduces imaging time and radiopharmaceutical doses (better detection sensitivity). The purpose of this study was to evaluate the left ventricular function parameters obtained by a fast low-dose clinical protocol on a CZT camera (D-SPECT), compared to the measurement on cardiac magnetic resonance imaging. Methods. - We retrospectively included patients who underwent MPI on D-SPECT camera with a low-dose of Sestamibi-99mTc (120 MBq for stress and 360 MBq at rest for a patient of 75 kg weight), and a cardiac magnetic resonance imaging, with a time less than two months. The left ventricular function was obtained at rest, with 8-frame reformatted, and analysis was performed using Quantitative Gated SPECT (QGS1) software. Results. - Seventy-seven patients were included and their mean ejection fraction (EF) was 45±13% at MRI. For D-SPECT recording, mean activity within heart area was 527±104 kcps, for mean recording time 3.5±2.2 min and mean of the total activity was 420±185 MBq (effective dose: 3.7±1.6 mSv). Correlation between D-SPECT and MRI was very good for EF (r = 0.88), end-diastolic volume (EDV, r = 0.90) and end-systolic volume (ESV, r = 0.96), but with an underestimation of all these parameters by the D-SPECT (on average, 5% absolute value for EF, and -16% and -24% in relative values for respectively ESV and EDV). Conclusion. - The evaluation of left ventricular function using the D-SPECT camera and with a fast low-dose protocol correlates well with that obtained by cardiac MRI, in the same patient. EF and ventricular volumes are however underestimated, in agreement with that previously documented with conventional Anger cameras. (authors)
[fr]
Introduction. - Les nouvelles gamma-cameras a semi-conducteurs (CZT) ont permis d'ameliorer la qualite des images de perfusion myocardique (meilleures resolutions spatiale et en energie) et de diminuer les activites injectees et les durees d'acquisition (meilleure sensibilite de detection). Le but de cette etude etait d'evaluer les parametres de la fonction ventriculaire gauche (VG) obtenus avec une camera CZT (la D-SPECT) avec un protocole a faible dose et un temps d'enregistrement reduit, par comparaison aux resultats obtenus en IRM cardiaque, examen de reference dans cette indication. Patients et methodes. - Nous avons inclus retrospectivement les patients ayant beneficie d'une tomoscintigraphie myocardique au sestamibi- 99mTc sur une camera D-SPECTavec un protocole en un jour a tres faible dose (120 MBq lors du stress pour 75 kg de poids corporel et 360 MBq au repos) et une IRM cardiaque a moins de deux mois d'intervalle. La fonction VG a ete analysee au repos avec la D-SPECT, 8 phases par cycle cardiaque et le logiciel QGS1. Resultats. - Soixante-dix-sept patients ont ete inclus et leur fraction d'ejection (FE) du VG etait en moyenne de 45±13 % en IRM. En D-SPECT, l'activite moyenne dans l'aire cardiaque etait de 527±104 kcps, pour des durees d'acquisition de 3,5±2,2 min et des activites totales injectees de 420±185 MBq (doses effectives : 3,7±1,6 mSv). Il y avait une tres bonne correlation entre D-SPECT et IRM pour les mesures de la FEVG (r = 0,88) et des volumes tele-diastoliques (VTD, r = 0,90) et tele-systoliques (VTS, r = 0,96), mais avec une sous-estimation des valeurs (en moyenne, 5 % en valeur absolue pour la FEVG et -16 et -24 % en valeurs relatives pour les VTS et VTD). Conclusion. - L'evaluation de la fonction VG par la camera D-SPECT, avec un protocole a faible dose et une courte acquisition, s'avere bien correlee a celle obtenue par l'IRM chez les memes patients, mais avec des sous-estimations de la FEVG et surtout des volumes, conformement a ce qui a ete deja observe avec les cameras conventionnelles. (auteurs)Journal
Medecine Nucleaire. Imagerie Fonctionnelle et Metabolique; ISSN 0928-1258; ; CODEN MNIMEX; v. 39(no.4); p. 401-408
; CODEN MNIMEX; v. 39(no.4); p. 401-408
[en] Aim of the study. - In the case of lung tumor treatment, to adjust 3D helical computed tomography (CT) acquisition parameters using a dynamic phantom and compare to the theory the volumes of a moving object. Materials and methods. - Three helical CT acquisitions were compared using a Big Bore CT scan: an 'initial' 3D CT scan (constructor parameters), an 'optimized' 3D CT scan which parameters are chosen to obtain an axial slow scan like acquisition and a 4D CT scan. We used a phantom composed by a ball filled with water set on a dynamic platform moving in the antero-posterior or cranio-caudal direction with a 14 mm amplitude and a 4 s period. For each acquisition and modality (static and dynamic), we quantified the ball volume by automatic contouring and we estimated relative errors. Results. - For an antero-posterior displacement, the volume of the moving ball is under estimated by 14.1 % with the 'initial' scan, by 0.2 % with the 'optimized' scan and over estimated by 0.8 % with the averaged 4D scan. For a cranio-caudal displacement, it is under estimated by about 22 % with the 'initial' scan and by about 1 % with the 'optimized' scan and the averaged 4D scan. Conclusion. - Volume measurements performed with the dynamic phantom allowed us to validate the 'optimized' 3D CT scan parameters because it accurately reflects the volume of a moving object. Radiotherapy departments without 4D CT should adapt scan parameters for internal target volume definition. (authors)
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