Contribution of high energy physics techniques to the medical imaging field

The purpose of this study was to show how advanced concepts of compact, lossless and "Time Of Flight" (TOF) capable electronics similar to those foreseen for the LHC and ILC experiments could be fairly and easily transferred to the medical imaging field through Positron Emission Tomography (PET). As a wish of explanation, the two overriding weaknesses of PET camera readout electronics, namely dead-time and timing resolution, were investigated analytically and with a Monte-Carlo simulator presently dedicated to this task. Results have shown there was room left for count rate enhancement through a huge decrease of the timing resolution well below the nanosecond. The novel electronics scheme suggested for PET in this paper has been partly inspired by the long experience led in High Energy Physics where the latter requirement is compulsory. Its structure entirely pipelined combined to a pixelation of the whole detector should allow dead-times to be suppressed, while the absence of devoted timing channel would remove the preponderant contributions to the timing resolution. To the common solution for timing would substitute an optimal filtering method witch clearly appears as a good candidate as timing resolution of a few tens of picoseconds may be achieved provided the shape of the signal is known and sufficient samples are available with enough accuracy. First investigations have yield encouraging results as a sampling frequency of 50 MHz with a 7 bits precision appears sufficient to ensure the 500ps coincidence timing resolution planed. At this point, there will be a baby step ahead to draw benefice from a TOF implementation to the design and the enormous noise variance enhancement that would come with.Comment: presented at EuroMedIm 2006 : 1st European Conference on Molecular Imaging Technology, Marseille 9-12 May 2006, 6 pp, 4 figures, submitted to NI

Contribution à l'étude des processus nucléaires en hadronthérapie et de leur impact sur la délocalisation du dépôt de dose

L hadronthérapie consiste en l utilisation des particules lourdes dans le but de soigner certains cancers inopérables et/ou résistants aux radiothérapies conventionnelles. L objectif est de déposer la dose nécessaire dans la tumeur afin de la stériliser, tout en limitant le dépôt de dose dans les tissus sains environnants. Le dépôt de dose est dû en grande partie à l ionisation de la cible directement par le faisceau incident, mais aussi dans une moindre mesure aux fragments produits par les interactions nucléaires entre les noyaux des projectiles et les noyaux des atomes de la cible. Ces processus nucléaires et leur contribution à la délocalisation de la distribution volumique du dépôt de dose sont difficilement quantifiables du fait de la mauvaise connaissance de leurs sections efficaces aux énergies utilisées en hadronthérapie. Le sujet principal de la thèse est de développer une méthodologie pour la quantification des incertitudes sur la dose effectivement délivrée, étant données les conditions d irradiation. Ce travail s est articulé autour de deux axes : une approche phénoménologique et une approche expérimentale. L approche phénoménologique a consisté en une étude bibliographique et une compilation des données expérimentales existantes, suite auxquelles le modèle empirique développé par Sihver et al. a été amélioré, permettant ainsi une meilleure description des sections efficaces de réaction totales et différentielles noyau-noyau pour un nombre de masse inférieur à 26. L approche expérimentale a consisté en deux prises de données: tout d abord la mesure du profil des émetteurs b+ dans une cible d eau irradiée par des ions carbone en utilisant la technique de tomographie à émission de positons au GANIL , puis la mesure de profils transversaux et longitudinaux de dépôt de dose dans des cible de graphite et de PMMA irradiées par des protons au PSI. Une méthode d analyse de données consistant à comparer les prédictions des simulations Monte Carlo aux mesures physiques a été ensuite développéeHadrontherapy consists of the use of heavy particles (hadrons) for treatment of radio-resistant or/and inoperable cancerous tumors. The aim is to deposit the necessary dose, in the tumor volume, to sterilize the cancerous cells while spearing the surrounding volumes. Dose deposition is mainly due to the electromagnetic interactions between the incoming beam particles and the target material leading principally to ionizations of the target molecular or atomic constituents. However, light nuclear fragments, issued from the nuclear interactions between the projectile and the target nuclei, do also contribute to the dose deposition. Even thought the amount of the later is small (few % of the total dose), its quantification is crucial since it is the main contribution to the dose delocalization out of the aimed target volume. This quantification is difficult because of the lack of experimental cross-sections at the energies used in hadrontherapy: a few tens or hundreds of MeV per nucleon of the projectile. The principal aim of this work is to develop a method in order to predict the dose distribution effectively delivered in the real conditions of therapeutic irradiation. Two complementary approaches were followed for this work. The first, phenomenological, consists of the study and the compilation of the existing experimental data available in the literature and the improvement of an empirical nuclear fragmentation cross-sections model. The second approach is purely experimental and concisted in two campaigns of data acquisition, mesaurement of b+ emitters profile in a water target irradiated by carbon ions at GANIL (Caen) using techniques of positron emission tomography, and acquisition of longitudinal and transversal dose distributions in carbon and water equivalent (PMMA) targets irradiated by protons at the PSI (Villigen) facility. Then a method of data analysis to compare the predictions of the Monte Carlo simulations to the measurements were developpedLYON1-BU.Sciences (692662101) / SudocSudocFranceF

Management practices for postdural puncture headache in obstetrics: a prospective, international, cohort study

© 2020 British Journal of AnaesthesiaBackground: Accidental dural puncture is an uncommon complication of epidural analgesia and can cause postdural puncture headache (PDPH). We aimed to describe management practices and outcomes after PDPH treated by epidural blood patch (EBP) or no EBP. Methods: Following ethics committee approval, patients who developed PDPH after accidental dural puncture were recruited from participating countries and divided into two groups, those receiving EBP or no EBP. Data registered included patient and procedure characteristics, headache symptoms and intensity, management practices, and complications. Follow-up was at 3 months. Results: A total of 1001 patients from 24 countries were included, of which 647 (64.6%) received an EBP and 354 (35.4%) did not receive an EBP (no-EBP). Higher initial headache intensity was associated with greater use of EBP, odds ratio 1.29 (95% confidence interval 1.19–1.41) per pain intensity unit increase. Headache intensity declined sharply at 4 h after EBP and 127 (19.3%) patients received a second EBP. On average, no or mild headache (numeric rating score≤3) was observed 7 days after diagnosis. Intracranial bleeding was diagnosed in three patients (0.46%), and backache, headache, and analgesic use were more common at 3 months in the EBP group. Conclusions: Management practices vary between countries, but EBP was more often used in patients with greater initial headache intensity. EBP reduced headache intensity quickly, but about 20% of patients needed a second EBP. After 7 days, most patients had no or mild headache. Backache, headache, and analgesic use were more common at 3 months in patients receiving an EBP

Management practices for postdural puncture headache in obstetrics : a prospective, international, cohort study

Background: Accidental dural puncture is an uncommon complication of epidural analgesia and can cause postdural puncture headache (PDPH). We aimed to describe management practices and outcomes after PDPH treated by epidural blood patch (EBP) or no EBP. Methods: Following ethics committee approval, patients who developed PDPH after accidental dural puncture were recruited from participating countries and divided into two groups, those receiving EBP or no EBP. Data registered included patient and procedure characteristics, headache symptoms and intensity, management practices, and complications. Follow-up was at 3 months. Results: A total of 1001 patients from 24 countries were included, of which 647 (64.6%) received an EBP and 354 (35.4%) did not receive an EBP (no-EBP). Higher initial headache intensity was associated with greater use of EBP, odds ratio 1.29 (95% confidence interval 1.19-1.41) per pain intensity unit increase. Headache intensity declined sharply at 4 h after EBP and 127 (19.3%) patients received a second EBP. On average, no or mild headache (numeric rating score <= 3) was observed 7 days after diagnosis. Intracranial bleeding was diagnosed in three patients (0.46%), and backache, headache, and analgesic use were more common at 3 months in the EBP group. Conclusions: Management practices vary between countries, but EBP was more often used in patients with greater initial headache intensity. EBP reduced headache intensity quickly, but about 20% of patients needed a second EBP. After 7 days, most patients had no or mild headache. Backache, headache, and analgesic use were more common at 3 months in patients receiving an EBP

Incidence of severe critical events in paediatric anaesthesia (APRICOT): a prospective multicentre observational study in 261 hospitals in Europe

Background Little is known about the incidence of severe critical events in children undergoing general anaesthesia in Europe. We aimed to identify the incidence, nature, and outcome of severe critical events in children undergoing anaesthesia, and the associated potential risk factors. Methods The APRICOT study was a prospective observational multicentre cohort study of children from birth to 15 years of age undergoing elective or urgent anaesthesia for diagnostic or surgical procedures. Children were eligible for inclusion during a 2-week period determined prospectively by each centre. There were 261 participating centres across 33 European countries. The primary endpoint was the occurence of perioperative severe critical events requiring immediate intervention. A severe critical event was defined as the occurrence of respiratory, cardiac, allergic, or neurological complications requiring immediate intervention and that led (or could have led) to major disability or death. This study is registered with ClinicalTrials.gov, number NCT01878760. Findings Between April 1, 2014, and Jan 31, 2015, 31 127 anaesthetic procedures in 30 874 children with a mean age of 6.35 years (SD 4.50) were included. The incidence of perioperative severe critical events was 5.2% (95% CI 5.0-5.5) with an incidence of respiratory critical events of 3.1% (2.9-3.3). Cardiovascular instability occurred in 1.9% (1.7-2.1), with an immediate poor outcome in 5.4% (3.7-7.5) of these cases. The all-cause 30-day in-hospital mortality rate was 10 in 10 000. This was independent of type of anaesthesia. Age (relative risk 0.88, 95% CI 0.86-0.90; p<0.0001), medical history, and physical condition (1.60, 1.40-1.82; p<0.0001) were the major risk factors for a serious critical event. Multivariate analysis revealed evidence for the beneficial effect of years of experience of the most senior anaesthesia team member (0.99, 0.981-0.997; p<0.0048 for respiratory critical events, and 0.98, 0.97-0.99; p=0.0039 for cardiovascular critical events), rather than the type of health institution or providers. Interpretation This study highlights a relatively high rate of severe critical events during the anaesthesia management of children for surgical or diagnostic procedures in Europe, and a large variability in the practice of paediatric anaesthesia. These findings are substantial enough to warrant attention from national, regional, and specialist societies to target education of anaesthesiologists and their teams and implement strategies for quality improvement in paediatric anaesthesia

Incidence of severe critical events in paediatric anaesthesia (APRICOT): a prospective multicentre observational study in 261 hospitals in Europe

Background Little is known about the incidence of severe critical events in children undergoing general anaesthesia in Europe. We aimed to identify the incidence, nature, and outcome of severe critical events in children undergoing anaesthesia, and the associated potential risk factors. Methods The APRICOT study was a prospective observational multicentre cohort study of children from birth to 15 years of age undergoing elective or urgent anaesthesia for diagnostic or surgical procedures. Children were eligible for inclusion during a 2-week period determined prospectively by each centre. There were 261 participating centres across 33 European countries. The primary endpoint was the occurence of perioperative severe critical events requiring immediate intervention. A severe critical event was defined as the occurrence of respiratory, cardiac, allergic, or neurological complications requiring immediate intervention and that led (or could have led) to major disability or death. This study is registered with ClinicalTrials.gov, number NCT01878760. Findings Between April 1, 2014, and Jan 31, 2015, 31â127 anaesthetic procedures in 30â874 children with a mean age of 6·35 years (SD 4·50) were included. The incidence of perioperative severe critical events was 5·2% (95% CI 5·0â5·5) with an incidence of respiratory critical events of 3·1% (2·9â3·3). Cardiovascular instability occurred in 1·9% (1·7â2·1), with an immediate poor outcome in 5·4% (3·7â7·5) of these cases. The all-cause 30-day in-hospital mortality rate was 10 in 10â000. This was independent of type of anaesthesia. Age (relative risk 0·88, 95% CI 0·86â0·90; p<0·0001), medical history, and physical condition (1·60, 1·40â1·82; p<0·0001) were the major risk factors for a serious critical event. Multivariate analysis revealed evidence for the beneficial effect of years of experience of the most senior anaesthesia team member (0·99, 0·981â0·997; p<0·0048 for respiratory critical events, and 0·98, 0·97â0·99; p=0·0039 for cardiovascular critical events), rather than the type of health institution or providers. Interpretation This study highlights a relatively high rate of severe critical events during the anaesthesia management of children for surgical or diagnostic procedures in Europe, and a large variability in the practice of paediatric anaesthesia. These findings are substantial enough to warrant attention from national, regional, and specialist societies to target education of anaesthesiologists and their teams and implement strategies for quality improvement in paediatric anaesthesia. Funding European Society of Anaesthesiology