[Comparison of foetal and neonatal mortality of monochorionic monoamniotic and monochorionic biamniotic twin pregnancies]. / Comparaison de la mortalité fœtale et néonatale des grossesses gémellaires monochoriales monoamniotiques et monochoriales biamniotiques.

OBJECTIVES: To compare the mortality of monochorionic-monoamniotic (MCMA) and monochorionic-biamniotic (MCBA) twin pregnancies, from 14weeks of gestation to 28th day of life, before and after exclusion of major congenital malformations. METHODS: We conducted a retrospective cohort study in two level 3 maternity units of the Hospices civils de Lyon (France) including all patients with a monochorionic twin pregnancy between January 2013 and December 2020. We excluded TRAP sequences and conjoined twins. RESULTS: A total of 38 MCMA and 658 MCBA pregnancies were included. We showed an increase in overall mortality in the MCMA group compared to the MCBA group (31.6% versus 16.4%, P=0.03) even after exclusion of major congenital malformations (20.3% versus 9.5%, P=0.01). The main cause of mortality found in the MCMA group was the occurrence of unexpected IUGR. CONCLUSIONS: MCMA pregnancies have a higher foetal and neonatal mortality rate than MCBA pregnancies even after exclusion of congenital malformations related to the occurrence of unexpected MFIU.

Smoking and smoking cessation in pregnancy. Synthesis of a systematic review.

OBJECTIVES: To provide up-to-date evidence-based guidelines for the management of smoking cessation during pregnancy and the post-partum period. STUDY DESIGN: A systematic review of the international literature was undertaken between January 2003 and April 2019. MEDLINE, EMBASE databases and the Cochrane library were searched for a range of predefined key words. All relevant reports in English and French were classified according to their level of evidence ranging from 1(highest) to 4(lowest). The strength of each recommendation was classified according to the Haute Autorité de Santé (French National Authority for Health) ranging from A (highest) to C (lowest). RESULTS: "Counselling", including all types of non-pharmacological interventions, has a moderate benefit on smoking cessation, birth weight and prematurity. The systematic use of measuring expired air CO concentration does not influence smoking abstinence, however, it may be useful in assessing smoked tobacco exposure prior to and after quitting. The use of self-help therapies and health education are recommended in helping pregnant smokers quit and should be advised by healthcare professionals. Nicotine replacement therapies (NRT) may be prescribed to pregnant women who have failed to stop smoking after trying non-pharmacological interventions. Different modes of delivery and dosages can be used in optimizing their efficacy. Smoking in the postpartum period is essential to consider. The same treatment options as during pregnancy can be used. CONCLUSION: Smoking during pregnancy concerns more than a hundred thousand women each year in France resulting in a major public health burden. Healthcare professionals should be mobilised to employ a range of methods to reduce or even eradicate it.

[CNGOF-SFT Expert Report and Guidelines for Smoking Management during Pregnancy-Short Text]. / Rapport d'experts et recommandations CNGOF-SFT sur la prise en charge du tabagisme en cours de grossesse­texte court.

OBJECTIVES: To provide up-to-date evidence-based guidelines for the management of smoking cessation during pregnancy. METHODS: Systematic review of the international literature. We identified papers published between January 2003 and April 2019 in Cochrane PubMed, and Embase databases with predefined keywords. All reports published in French and English relevant to the areas of focus were included and classified according the level of evidence ranging from 1 (highest) to 4 (lowest). The strength of the recommendations was classified according to the Haute Autorité de santé, France (ranging from A, highest to C, lowest). RESULTS: "Counseling", involving globally all kind of non-pharmacological interventions, has a modest benefit on smoking cessation, birth weight and prematurity. Moderate physical activity did not show a significant effect on smoking cessation. The systematic use of feedback by measuring the expired air carbon monoxide concentration do not influence smoking abstinence but it may be used in establishing a therapeutic alliance. The use of self-help interventions and health education are recommended in helping pregnant smokers quit. The prescription of nicotine replacement therapies (NRT) may be offered to any pregnant woman who has failed stopping smoking without medication This prescription can be initiated by the health care professional taking care of the pregnant woman in early pregnancy. There is no scientific evidence to propose the electronic cigarette for smoking cessation to pregnant smokers; it is recommended to provide the same advice and to use methods that have already been evaluated. The use of waterpipe (shisha/narghile) during pregnancy is associated with decreased fetal growth. It is recommended not to use waterpipe during pregnancy. Breastfeeding is possible in smokers, but less often initiated by them. Although its benefit for the child's development is not demonstrated to date, breastfeeding allows the mother to reduce or stop smoking. The risk of postpartum relapse is high (up to 82% at 1 year). The main factors associated with postpartum abstinence are breastfeeding, not having a smoker at home, and having no symptoms of postpartum depression. CONCLUSIONS: Smoking during pregnancy concerns more than hundred thousand women and their children per year in France. It is a major public health burden. Health care professionals should be mobilized for reducing or even eradicating it.

[N on-pharmacological management of smoking cessation during pregnancy- CNGOF-SFT Expert Report and Guidelines for Smoking Management during Pregnancy]. / Prise en charge non pharmacologique du sevrage tabagique pendant la grossesse ­ Rapport d'experts et recommandations CNGOF-SFT sur la prise en charge du tabagisme en cours de grossesse.

OBJECTIVES: To assess the benefit of non-pharmacological intervention promoting on smoking cessation, obstetric and neonatal outcomes, to offer pregnant women who smoke (PWS) optimal care. METHODS: We searched Medline Database, Cochrane Library and consulted international guidelines. RESULTS: "Counselling" involving globally all kind of non-pharmacological interventions has a benefit on smoking cessation (NP1) and a moderate benefit on birth weight and prematurity (NP2). The brief intervention seems ineffective on smoking cessation (NP2). The effects of motivational interviewing have not been demonstrated during pregnancy (NP2). Cognitive-behavioral interventions do not show superiority (NP2). Financial incentives have a benefit for smoking cessation and possibly for neonatal outcomes (NP1). Feedback interventions (Co tester) provide heterogeneous results (NP2). Self-help interventions (NP2) and health education (NP2) seem effective on smoking cessation. Hypnotherapy and acupuncture have been little or not studied in PWS. Moderate physical activity did not show a significant effect (NP2) on smoking cessation but seem to reduce craving for tobacco (NP3). CONCLUSIONS: We recommend asking all PWS about their smoking consumption and detailing their smoking history, offering them different types of counselling according to their preferences and involving them multidisciplinary (grade A). The systematic use of feedback is not recommended (grade C) but experience suggests that the CO tester is important in establishing a therapeutic alliance (professional consensus). The use of self-help interventions (grade C) and health education (grade B) are recommended.

[Passive Smoking and Pregnancy - CNGOF-SFT Expert Report and Guidelines for Smoking Management during Pregnancy]. / Conséquence du tabagisme passif chez la femme enceinte ­ Rapport d'experts et recommandations CNGOF-SFT sur la prise en charge du tabagisme en cours de grossesse.

OBJECTIVE: The objective of this chapter is to evaluate the risks of second-hand-smoke during pregnancy and to assess the benefits of antenatal care. METHODS: Bibliographical research in French and English using the Medline and Cochrane databases and the recommendations of international societies. RESULTS: Exposure to second-hand smoke appears to be higher at home and in the car, with potential consequences for pregnancy, especially prematurity (NP3). Complete avoidance of smoking at home significantly reduces exposure to passive smoking compared to incomplete avoidance (NP4). The more numerous the sources, the higher the intoxication is (NP4). The major risk factor associated with passive smoking is the presence of a spouse who smokes. Other associated factors are the presence of a smoker at home or in the car, young population (<25 years), low level of education, old smoking (NP4). Passive smoking is associated with an increased risk of fetal death in utero, fetal malformations, prematurity and birth weight under 2500g (NP2). No specific management is recommended for all pregnant women. Nevertheless, in a specific population of pregnant women with vulnerabilities, a behavioral approach aimed at teaching them to negotiate with their entourage may be beneficial in order to reduce the effects of passive smoking on pregnancy (NP2). CONCLUSION: It is recommended to advise women and their family (especially spouses) to create a smoke-free environment, especially at home and in the car (professional consensus). It is recommended to provide a minimum amount of smoking cessation advice to pregnant women's entourage (professional consensus).

[Physiological and Psychological Data influencing Pregnant Women Smoking Behavior - CNGOF-SFT Expert Report and Guidelines for Smoking Management during Pregnancy]. / Données physiologiques et psychologiques influençant le comportement tabagique de la femme enceinte ­ Rapport d'experts et recommandations CNGOF-SFT sur la prise en charge du tabagisme en cours de grossesse.

Nicotine is the main addictive substance in tobacco and its addictive effects mainly involve dopamine. Nicotine is mainly metabolized (C-oxidation) in the liver to cotinine by the cytochrome P450 enzyme system. Nicotine half-life is short being about 2hours. Nicotine metabolism appears to be increased during pregnancy, mainly due to an increased cytochrome activity and maternal cardiac output. Thus, the smoking behavior of the pregnant woman is subsequently modified with an increase in withdrawal syndromes and an increased desire to smoke. These pharmacological elements should be taken into account when prescribing nicotine replacement therapy. Regarding the markers of tobacco intoxication, there is a good correlation between the importance of smoking and the measurement of expired air carbon monoxide. Although there is no evidence of decreased obstetrical complications related to its use, it is simple and non-invasive and therefore may be useful in routine practice. It gives an instantaneous value of tobacco intoxication, and represents a starting point for dialogue and management and can help to highlight the reality of withdrawal. Regarding the evaluation of tobacco addiction, the most commonly used questionnaires are the Fagerström tests (FTCD, HSI…), which are well correlated with cotinine concentration. However, there is insufficient evidence of their usefulness in reducing tobacco consumption during pregnancy to recommend them in current practice. DSM-V diagnostic criteria for addiction should be known as they can also be used to characterize the intensity of this addiction.

Integration of the M6 Cyberknife in the Moderato Monte Carlo platform and prediction of beam parameters using machine learning.

PURPOSE: This work describes the integration of the M6 Cyberknife in the Moderato Monte Carlo platform, and introduces a machine learning method to accelerate the modelling of a linac. METHODS: The MLC-equipped M6 Cyberknife was modelled and integrated in Moderato, our in-house platform offering independent verification of radiotherapy dose distributions. The model was validated by comparing TPS dose distributions with Moderato and by film measurements. Using this model, a machine learning algorithm was trained to find electron beam parameters for other M6 devices, by simulating dose curves with varying spot size and energy. The algorithm was optimized using cross-validation and tested with measurements from other institutions equipped with a M6 Cyberknife. RESULTS: Optimal agreement in the Monte Carlo model was reached for a monoenergetic electron beam of 6.75 MeV with Gaussian spatial distribution of 2.4 mm FWHM. Clinical plan dose distributions from Moderato agreed within 2% with the TPS, and film measurements confirmed the accuracy of the model. Cross-validation of the prediction algorithm produced mean absolute errors of 0.1 MeV and 0.3 mm for beam energy and spot size respectively. Prediction-based simulated dose curves for other centres agreed within 3% with measurements, except for one device where differences up to 6% were detected. CONCLUSIONS: The M6 Cyberknife was integrated in Moderato and validated through dose re-calculations and film measurements. The prediction algorithm was successfully applied to obtain electron beam parameters for other M6 devices. This method would prove useful to speed up modelling of new machines in Monte Carlo systems.

[Radiotherapy treatment planning of prostate cancer using magnetic resonance imaging]. / Planification de la radiothérapie du cancer de la prostate par l'imagerie par résonance magnétique.

PURPOSE: Magnetic resonance imaging (MRI) plays an increasing role in radiotherapy dose planning. Indeed, MRI offers superior soft tissue contrast compared to computerized tomography (CT) and therefore could provide a better delineation of target volumes and organs at risk than CT for radiotherapy. Furthermore, an MRI-only radiotherapy workflow would suppress registration errors inherent to the registration of MRI with CT. However, the estimation of the electronic density of tissues using MRI images is still a challenging issue. The purpose of this work was to design and evaluate a pseudo-CT generation method for prostate cancer treatments. MATERIALS AND METHODS: A pseudo-CT was generated for ten prostate cancer patients using an elastic deformation based method. For each patient, dose delivered to the patient was calculated using both the planning CT and the pseudo-CT. Dose differences between CT and pseudo-CT were investigated. RESULTS: Mean dose relative difference in the planning target volume is 0.9% on average and ranges from 0.1% to 1.7%. In organs at risks, this value is 1.8%, 0.8%, 0.8% and 1% on average in the rectum, the right and left femoral heads, and the bladder respectively. CONCLUSION: The dose calculated using the pseudo-CT is very close to the dose calculated using the CT for both organs at risk and PTV. These results confirm that pseudo-CT images generated using the proposed method could be used to calculate radiotherapy treatment doses on MRI images.

About the non-consistency of PTV-based prescription in lung.

PURPOSE: The goal of this study is to show that the PTV concept is inconsistent for prescribing lung treatments when using type B algorithms, which take into account lateral electron transport. It is well known that type A dose calculation algorithms are not capable of calculating dose in lung correctly. Dose calculations should be based on type B algorithms. However, the combination of a type B algorithm with the PTV concept leads to prescription inconsistencies. METHODS: A spherical isocentric setup has been simulated, using multiple realistic values for lung density, tumor density and collimator size. Different prescription methods are investigated using Dose-Volume-Histograms (DVH), Dose-Mass-Histograms (DMH), generalized Equivalent Uniform Dose (gEUD) and surrounding isodose percentage. RESULTS: Isodose percentages on the PTV drop down to 50% for small tumors and low lung density. When applying the same PTV prescription to different patients with different lung characteristics, the effective mean dose to the GTV is very different, with factors up to 1.4. The most consistent prescription method seems to be the D50%DMH (PTV) DMH point, but is also limited to tumors with size over 1cm. CONCLUSIONS: Even when using the different prescription methods, the prescription to the PTV is not consistent for type B-algorithm based dose calculations if clinical studies should produce coherent data. This combination leads to patients' GTV with low lung density possibly receiving very high dose compared to patients with higher lung density. The only solution seems to remove the classical PTV concept for type B dose calculations in lung.

Clinical implementation of a Monte Carlo based treatment plan QA platform for validation of Cyberknife and Tomotherapy treatments.

PURPOSE: The main focus of the current paper is the clinical implementation of a Monte Carlo based platform for treatment plan validation for Tomotherapy and Cyberknife, without adding additional tasks to the dosimetry department. METHODS: The Monte Carlo platform consists of C++ classes for the actual functionality and a web based GUI that allows accessing the system using a web browser. Calculations are based on BEAMnrc/DOSXYZnrc and/or GATE and are performed automatically after exporting the dicom data from the treatment planning system. For Cyberknife treatments of moving targets, the log files saved during the treatment (position of robot, internal fiducials and external markers) can be used in combination with the 4D planning CT to reconstruct the actually delivered dose. The Monte Carlo platform is also used for calculation on MRI images, using pseudo-CT conversion. RESULTS: For Tomotherapy treatments we obtain an excellent agreement (within 2%) for almost all cases. However, we have been able to detect a problem regarding the CT Hounsfield units definition of the Toshiba Large Bore CT when using a large reconstruction diameter. For Cyberknife treatments we obtain an excellent agreement with the Monte Carlo algorithm of the treatment planning system. For some extreme cases, when treating small lung lesions in low density lung tissue, small differences are obtained due to the different cut-off energy of the secondary electrons. CONCLUSIONS: A Monte Carlo based treatment plan validation tool has successfully been implemented in clinical routine and is used to systematically validate all Cyberknife and Tomotherapy plans.

Accurate Monte Carlo modelling of the back compartments of SPECT cameras.

Today, new single photon emission computed tomography (SPECT) reconstruction techniques rely on accurate Monte Carlo (MC) simulations to optimize reconstructed images. However, existing MC scintillation camera models which usually include an accurate description of the collimator and crystal, lack correct implementation of the gamma camera's back compartments. In the case of dual isotope simultaneous acquisition (DISA), where backscattered photons from the highest energy isotope are detected in the imaging energy window of the second isotope, this approximation may induce simulation errors. Here, we investigate the influence of backscatter compartment modelling on the simulation accuracy of high-energy isotopes. Three models of a scintillation camera were simulated: a simple model (SM), composed only of a collimator and a NaI(Tl) crystal; an intermediate model (IM), adding a simplified description of the backscatter compartments to the previous model and a complete model (CM), accurately simulating the materials and geometries of the camera. The camera models were evaluated with point sources ((67)Ga, (99m)Tc, (111)In, (123)I, (131)I and (18)F) in air without a collimator, in air with a collimator and in water with a collimator. In the latter case, sensitivities and point-spread functions (PSFs) simulated in the photopeak window with the IM and CM are close to the measured values (error below 10.5%). In the backscatter energy window, however, the IM and CM overestimate the FWHM of the detected PSF by 52% and 23%, respectively, while the SM underestimates it by 34%. The backscatter peak fluence is also overestimated by 20% and 10% with the IM and CM, respectively, whereas it is underestimated by 60% with the SM. The results show that an accurate description of the backscatter compartments is required for SPECT simulations of high-energy isotopes (above 300 keV) when the backscatter energy window is of interest.