Retrospective observational study on the impact of the Covid-19 pandemic on the prescription of medications for the treatment of Attention Deficit/Hyperactivity Disorder. Comparison of a European and an American cohort

BACKGROUND

Attention Deficit Hyperactivity Disorder (ADHD) is a neuropsychological disorder that affects the development of children and adolescents. The causes are not fully known although the origin of the disorder appears to depend on a combination of environmental, social, biochemical, and genetic factors. There is substantial evidence the Covid-19 pandemic caused an increase in mental disorders and therefore in spending related to the treatment of diseases.

METHOD

We conducted a retrospective cohort study in two international centers of very different origins and cultures, one in Europe (Italy) and one in Central America (Costa Rica), to assess the impact of the Covid-19 pandemic on ADHD medication prescriptions and its costs. The analysis resulting from mining the databases in each individual nation allowed for the actual amounts of defined daily dose (DDD) prescribed and dispensed between the years 2019 and 2022 of methylphenidate and atomoxetine.

RESULTS

The data show that the Italian ADHD medications DDDs and expenditure are aligned with the results in Costa Rica. It was found that from the year 2019 to the year 2022, both methylphenidate and atomoxetine prescriptions grew steadily, confirming a much higher incidence of the condition than in pre-pandemic periods.

CONCLUSIONS

Our study shows that the global pandemic had an influence on the increase in the number of ADHD medication prescriptions. Individuals with ADHD are a population of individuals who may be particularly vulnerable to the distress caused by the pandemic, restrictions, and severe physical removal measures that have occurred in recent years.

[Esclerosis multiple. Lactancia. Lactante. Planificacion familiar. Posparto. Tratamiento modificador de la enfermedad.]

INTRODUCTION

Multiple sclerosis mainly affects women of childbearing age, and the pregnancy and postpartum period is of special interest because of the peculiarities of the disease course and the therapeutic consequences that derive from it. During the period of breastfeeding (BF), the choice of treatment strategy must weigh up the well-established benefits of BF for both the newborn and the mother against the safety profile and potential adverse effects on the infant resulting from exposure to disease-modifying drugs transferred through breast milk.

DEVELOPMENT

The study reviews the current evidence on the safety of disease-modifying drugs available for the treatment of multiple sclerosis during the BF period, and gathers data on the transfer of the different drugs into breast milk, as well as the potential adverse effects described in the infant. The drugs of first choice during this period are interferon beta and glatiramer acetate. The rest of the disease modifying drugs are not accepted for use in the BF period according to their summary of product characteristics. However, in recent years, data from studies of clinical practice and case series have been published suggesting that some of these drugs could be used safely during this period.

CONCLUSIONS

Given the recognised health benefits of BF for both mother and infant, exclusive breastfeeding is recommended whenever possible. It is essential to carry out an individualised assessment prior to pregnancy and to evaluate the different treatment options depending on each patient.

Worldwide use of HPV self-sampling for cervical cancer screening

An increasing body of evidence supports the validity of self-sampling as an alternative to clinician collection for primary Human Papillomavirus (HPV) screening. Self-sampling effectively reaches underscreened women and can be a powerful strategy in low- and high-resource settings for all target ages. This work aims to summarize the current use of HPV self-sampling worldwide. It is part of a larger project that describes cervical cancer screening programmes and produces standardized coverage estimates worldwide. A systematic review of the literature and official documents supplemented with a formal World Health Organisation country consultation was conducted. Findings show that the global use of HPV self-sampling is still limited. Only 17 (12%) of countries with identified screening programs recommend its use, nine as the primary collection method, and eight to reach underscreened populations. We identified 10 pilots evaluating the switch to self-sampling in well-established screening programs. The global use of self-sampling is likely to increase in the coming years. COVID-19's pandemic has prompted efforts to accelerate HPV self-sampling introduction globally, and it is now considered a key element in scaling up screening coverage. The information generated by the early experiences can be beneficial for decision-making in both new and existing programs.

Diagnostic accuracy of first-trimester combined screening for early-onset and preterm pre-eclampsia at 8-10 compared with 11-13 weeks' gestation

OBJECTIVES

To compare the ability of first-trimester combined screening for pre-eclampsia (PE) to predict early-onset and preterm PE when pregnancy-associated plasma protein-A (PAPP-A) and placental growth factor (PlGF) were assessed before vs after 11 weeks' gestation.

METHODS

This was a secondary analysis of a prospective cohort study of singleton pregnancies undergoing routine first-trimester screening conducted at Vall d'Hebron University Hospital, Barcelona, Spain, between October 2015 and September 2017. Demographic characteristics, obstetric history, maternal history and biophysical markers (mean uterine artery pulsatility index and mean arterial blood pressure (MAP)) were recorded at the first-trimester scan (at 11 + 0 to 13 + 6 weeks' gestation). Maternal serum concentrations of PAPP-A and PlGF were assessed from the routine first-trimester blood test (at 8 + 0 to 13 + 6 weeks). Women were classified into two groups depending on whether serum biomarkers were assessed at 8 + 0 to 10 + 6 weeks or at 11 + 0 to 13 + 6 weeks. Probability scores for early-onset and preterm PE were calculated by using two different algorithms: the multivariate Gaussian-distribution model and The Fetal Medicine Foundation (FMF) competing-risks model. Receiver-operating-characteristics (ROC) curves were produced and detection rates at fixed 5% and 10% false-positive rates were computed to compare the performance of these algorithms when PAPP-A and PlGF were assessed before vs after 11 weeks.

RESULTS

Of the 2641 women included, serum biomarkers were assessed before 11 weeks in 1675 (63.4%) and at or after 11 weeks in 966 (36.6%). Of these, 90 (3.4%) women developed PE, including 11 (0.4%) cases of early-onset PE and 30 (1.1%) of preterm PE. Five (45.5%) cases of early-onset and 16 (53.3%) of preterm PE were identified in the group in which serum biomarkers were assessed at 8 + 0 to 10 + 6 weeks and six (54.5%) cases of early-onset and 14 (46.7%) of preterm PE in the group in which serum biomarkers were assessed at 11 + 0 to 13 + 6 weeks. In the prediction of early-onset and preterm PE using the Gaussian algorithm, no differences were observed between the areas under the ROC curves (AUCs) when PAPP-A and PlGF were measured before or after 11 weeks. In the prediction of early-onset and preterm PE using the FMF algorithm, no differences were observed between AUCs for any of the combinations used for risk calculation when the serum biomarkers were obtained before vs after 11 weeks, except for the combination of PAPP-A and MAP, which showed a greater AUC for the prediction of early-onset PE when PAPP-A was measured at or after 11 weeks.

CONCLUSIONS

The prediction of early-onset and preterm PE is similar when serum biomarkers are measured before or after 11 weeks. This allows the use of a two-step approach for PE risk assessment that permits immediate risk calculation at the time of the first-trimester scan. © 2020 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Pre-eclampsia-like syndrome induced by severe COVID-19: a prospective observational study

OBJECTIVES

To investigate the incidence of clinical, ultrasonographic and biochemical findings related to pre-eclampsia (PE) in pregnancies with COVID-19, and to assess their accuracy to differentiate between PE and the PE-like features associated with COVID-19.

DESIGN

A prospective, observational study.

SETTING

Tertiary referral hospital.

PARTICIPANTS

Singleton pregnancies with COVID-19 at >20+0  weeks.

METHODS

Forty-two consecutive pregnancies were recruited and classified into two groups: severe and non-severe COVID-19, according to the occurrence of severe pneumonia. Uterine artery pulsatility index (UtAPI) and angiogenic factors (soluble fms-like tyrosine kinase-1/placental growth factor [sFlt-1/PlGF]) were assessed in women with suspected PE.

MAIN OUTCOME MEASURES

Incidence of signs and symptoms related to PE, such as hypertension, proteinuria, thrombocytopenia, elevated liver enzymes, abnormal UtAPI and increased sFlt-1/PlGF.

RESULTS

Thirty-four cases were classified as non-severe and 8 as severe COVID-19. Five (11.9%) women presented signs and symptoms of PE, all five being among the severe COVID-19 cases (62.5%). However, abnormal sFlt-1/PlGF and UtAPI could only be demonstrated in one case. One case remained pregnant after recovery from severe pneumonia and had a spontaneous resolution of the PE-like syndrome.

CONCLUSIONS

Pregnant women with severe COVID-19 can develop a PE-like syndrome that might be distinguished from actual PE by sFlt-1/PlGF, LDH and UtAPI assessment. Healthcare providers should be aware of its existence and monitor pregnancies with suspected pre-eclampsia with caution.

TWEETABLE ABSTRACT

This study shows that a pre-eclampsia-like syndrome could be present in some pregnancies with severe COVID-19.

[Spanish adaptation of the 2016 European Guidelines on cardiovascular disease prevention in clinical practice]

The VI European Guidelines for Cardiovascular Prevention recommend combining population and high-risk strategies with lifestyle changes as a cornerstone of prevention, and propose the SCORE function to quantify cardiovascular risk. The guidelines highlight disease specific interventions, and conditions as women, young people and ethnic minorities. Screening for subclinical atherosclerosis with noninvasive imaging techniques is not recommended. The guidelines distinguish four risk levels (very high, high, moderate and low) with therapeutic objectives for lipid control according to risk. Diabetes mellitus confers a high risk, except for subjects with type 2 diabetes with less than <10 years of evolution, without other risk factors or complications, or type 1 diabetes of short evolution without complications. The decision to start pharmacological treatment of arterial hypertension will depend on the blood pressure level and the cardiovascular risk, taking into account the lesion of target organs. The guidelines don't recommend antiplatelet drugs in primary prevention because of the increased bleeding risk. The low adherence to the medication requires simplified therapeutic regimes and to identify and combat its causes. The guidelines highlight the responsibility of health professionals to take an active role in advocating evidence-based interventions at the population level, and propose effective interventions, at individual and population level, to promote a healthy diet, the practice of physical activity, the cessation of smoking and the protection against alcohol abuse.

Plasma concentrations of pregnancy-associated glycoproteins measured using anti-bovine PAG-2 antibodies on day 120 of gestation predict abortion in dairy cows naturally infected with Neospora caninum

The present study sought to determine: (i) the effects of Neospora caninum infection and twin pregnancy on plasma pregnancy-associated glycoprotein-2 (PAG-2) concentrations throughout pregnancy and (ii) whether plasma PAG-2 concentrations could predict abortion in N. caninum-infected cows. The study was performed on a commercial Holstein-Friesian dairy herd in northeastern Spain and the final data included those recorded in 53 non-aborting and 19 aborting animals. Blood samples were collected immediately before pregnancy diagnosis (on Days 40, 90, 120, 150, 180 and 210 post-insemination) in non-aborting cows or until the time of abortion detection in aborting cows. General lineal models (GLM) repeated measures anova revealed the different behaviour of PAG-1 and PAG-2, and significant effects of Neospora seropositivity, cool season and twin pregnancy on plasma PAG-2 concentrations throughout gestation (between-subject effects). In addition, based on the odds ratios, the likelihood of abortion increased in Neospora-seropositive cows (by a factor of 7.0) compared to seronegative animals and decreased in cows with a high plasma PAG-2 concentration (>4.5 ng/ml) on Day 120 of pregnancy (by a factor of 0.24), compared to the remaining cows. In conclusion, there is a relationship between plasma PAG-2 concentrations and the risk of abortion in Neospora-infected dairy cows. Thus, plasma PAG concentrations measured using anti-boPAG-2 antiserum on Day 120 of gestation could serve as an indicator of the abortion risk in N. caninum infected animals; values <4.5 ng/ml indicating a high risk of abortion in chronically infected animals.

Coxiella burnetii shedding during the peripartum period and subsequent fertility in dairy cattle

The objective of this study was to assess the effects of Coxiella burnetii shedding or seropositivity on post-partum recovery and subsequent fertility in high-producing dairy cows. Given the difficulty in diagnosing C. burnetii infection at the farm level, an exhaustive series of tests in 43 pregnant animals that delivered at least one live calf were conducted, including blood serology and PCR of milk or colostrum, cotyledons (only at parturition), faeces, vaginal fluid against C. burnetii on gestation Day 171-177, at parturition and on Days 1-7, 8-14, 15-21, 22-28, 29-35 and 90-97 post-partum. During scheduled herd visits, ultrasonography (US) of the genital tract and examination of vaginal fluid were performed on Days 15-21 (V1), 22-28 (V2), 29-35 (V3) and 51-57 (V4) post-partum by the same veterinarian. Logistic regression analysis revealed that the likelihood of suffering endometritis (the presence of echogenic intrauterine fluid (IUF), cervical diameter of ≥4 cm or endometrial thickness ≥0.75 cm) was lower in C. burnetii-seropositive animals (OR = 0.10), compared with C. burnetii-seronegative animals. According to Kaplan-Meier survival analysis, C. burnetii-seronegative and non-shedding cows showed a delayed return to luteal activity and conception was delayed in non-shedding animals, compared with the remaining animals. Overall, the results of our study provide useful insight into the effects of C. burnetii infection on post-partum recovery and subsequent fertility. In particular, animals not infected with Coxiella seem to be susceptible to infection and not protected against the bacterium in dairy herds. The elevated costs of determining an infection at the farm level, make monitoring of cows virtually impossible from a clinical point of view.

Dynamics of Coxiella burnetii antibodies and seroconversion in a dairy cow herd with endemic infection and excreting high numbers of the bacterium in the bulk tank milk

Possible factors related to seropositivity and seroconversion to Coxiella burnetii were examined in a dairy herd with a high Coxiella-seroprevalence and high excretion levels of the bacterium in the bulk tank milk. Antibodies were detected by using a commercial ELISA test in 50.7% of 603 parous cows. The likelihood of C. burnetii seropositivity significantly increased by factors of 1.87 and 1.61 for cows in their first and second terms of pregnancy, respectively, compared to non-pregnant cows. In 478 cows tested twice 12 months apart, the seroconversion rate was 5%. The likelihood of C. burnetii-seroconversion was 2.27 times lower in multiparous than in primiparous cows and 6.88 times higher in cows during their first 90 days in milk than dry-off cows. Our findings indicated a higher seroprevalence in the first and second terms of pregnancy, and that seroconversion mainly occurred in primiparous cows during their first 90 days in milk.

Cytokine gene expression profiles in peripheral blood mononuclear cells from Neospora caninum naturally infected dams throughout gestation

Neospora caninum is a major cause of abortion in cattle but it is not known why some infected animals suffer abortion while others do not. An essential role in protective immunity against N. caninum has been proposed for Th1 cytokines such as IFN-γ and IL-12 although cytokine patterns in N. caninum infected pregnant cattle have been scarcely addressed. In this study, gene expression of the cytokines IFN-γ, IL-12, IL-10, IL-4 and TNF-α was analyzed by real time RT-PCR in peripheral blood mononuclear cells in N. caninum naturally infected dams throughout pregnancy. Blood samples were drawn from 18 cows (13 N. caninum seropositive and 5 N. caninum seronegative) on Days 45, 90, 120, 150, 180 and 210 of pregnancy or until abortion. Four seropositive animals aborted. Compared to the seronegative animals, N. caninum infected dams showed up-regulated mRNA levels of the Th1 cytokines, IFN-γ, TNF-α and IL-12p40, along with up-regulation of the T regulatory (Treg) cytokine IL-10. In contrast, expression levels of IL-4 (Th2 cytokine) did not differ significantly among the different groups throughout the study period. Our findings indicate clear differences in peripheral blood cytokine gene expression levels during pregnancy between animals naturally infected with N. caninum and seronegative control animals. To the best of our knowledge, this is the first study to examine the gene expression of Th1, Th2 and regulatory cytokines in the peripheral blood of pregnant cows naturally infected with N. caninum.

Peripheral white blood cell counts throughout pregnancy in non-aborting Neospora caninum-seronegative and seropositive high-producing dairy cows in a Holstein Friesian herd

Pregnancy is characterized by transient changes in the maternal immune system, also evident at peripheral level. The present study analyzes the kinetics and possible factors affecting peripheral white blood cell populations throughout pregnancy in a herd of high-producing dairy cows chronically infected or not with Neospora caninum. We examined 54 pregnant parous cows: 29 Neospora-seronegative and 25 Neospora-seropositive cows. Blood samples were collected on Days 90, 120, 150, 180 and 210 of gestation. General Linear Model (GLM) repeated measures analysis of variance showed that the interaction Neospora-seropositivity × parity significantly affected total leukocyte, neutrophil and monocyte counts with lower levels of total leukocytes, lower neutrophil and higher monocyte counts recorded in primiparous Neospora-seropositive cows. In addition, N. caninum-seropositive cows had significantly increased monocyte counts on Day 180 of gestation compared to seronegative ones. Other factors significantly associated with changes in total and/or differential leukocyte profiles were period of pregnancy, season, twin pregnancy and milk production. In conclusion, a parity-associated effect of chronic N. caninum infection was observed on peripheral blood cell profiles in dairy cattle during gestation.

Effects of highly active antiretroviral therapy on vaccine-induced humoral immunity in HIV-infected adults

OBJECTIVES

The acquisition of adequate vaccine-induced humoral immunity is especially important in HIV-infected individuals, who are at increased risk of infections. The aim of the study was to assess the safety of administering a complete vaccination programme to successfully treated HIV-infected adults and to evaluate specific humoral responses and the effect of highly active antiretroviral therapy (HAART) interruption on these responses.

METHODS

A placebo-controlled, double-blind clinical trial was designed and 26 HIV-infected adults enrolled. Study participants were randomized to receive either a complete immunization schedule with commercial vaccines or placebo for 12 months. HAART was then discontinued for 6 months. Specific humoral responses were evaluated at baseline, at month 12 and after HAART interruption and compared between groups.

RESULTS

There were neither local nor systemic secondary effects related to vaccination. Specific humoral responses to vaccines were adequate, but a loss of immunoglobulin G titres was observed after HAART interruption in 12 study participants.

CONCLUSIONS

HAART interruption may cause impairment of previously acquired vaccine-induced immunity in HIV-infected adults.

Factors affecting plasma pregnancy-associated glycoprotein 1 concentrations throughout gestation in high-producing dairy cows

This study was designed to establish the factors, if any, which could affect plasma pregnancy-associated glycoprotein-1 (PAG-1) expression in a study population of 87 pregnant, high-producing dairy cows. The factors examined were: semen providing breed (Holstein-Friesian vs Limousin), outcome of gestation (male vs female newborn, and singleton vs twin pregnancies), lactation number, milk production at pregnancy diagnosis, plasma progesterone concentration, season of gestation (warm period, March-November vs cool period, December-February), and day of gestation (40, 90, 120, 150, 180 and 210). Pregnancy was diagnosed by transrectal ultrasound on day 40 post-insemination and by palpation per rectum on days 90, 120, 150, 180 and 210. Blood samples were collected from each animal immediately before each pregnancy diagnosis. The relative contributions of the different factors on PAG-1 concentrations were evaluated by GLM repeated measures analysis of variance. No significant effects of the herd, foetal sex, milk production, lactation number and plasma progesterone concentrations were observed. In contrast, twin pregnancy, the use of Limousin semen and conception during the cool period were correlated with significantly increased plasma PAG-1 concentrations throughout gestation. Our data indicate that both cow well-being during early placental development, determined in our conditions by reduced heat stress when conception occurred in the cool season, and crossbreed pregnancies lead to improved PAG-1 production throughout the gestation period.

Factors affecting plasma prolactin concentrations throughout gestation in high producing dairy cows

The aim of the present study was to investigate possible relationships between plasma concentrations of prolactin and the following factors throughout gestation in lactating dairy cows: photoperiod, season, milk production, Neospora caninum-seropositivity, twin pregnancy, and plasma concentrations of pregnancy associated glycoproteins-1 (PAG-1), progesterone and cortisol. Pregnancy was diagnosed by trans-rectal ultrasonography on Day 40 post-insemination and by palpation per rectum on Days 90, 120, 150, 180 and 210 or until abortion in aborting cows. Blood samples were collected from each animal immediately before each pregnancy diagnosis. The study population was comprised of 73 non-aborting (54 Neospora-seropositive cows) and 20 aborting cows (all Neospora-seropositive) cows. In non-aborting cows, GLM repeated measures of analysis of variance revealed that lactation number and days in milk had no effect on plasma prolactin concentrations throughout gestation, whereas high plasma prolactin concentrations were significantly associated with high plasma levels of cortisol and PAG-1, with Neospora-seropositivity, positive photoperiod (increasing day length), twin pregnancy, and with low plasma progesterone concentrations. An interaction among plasma prolactin, plasma cortisol and milk production was observed in that plasma prolactin concentrations differed significantly throughout gestation and were highest in high-producing cows with high cortisol levels. In Neospora-seropositive non-aborting versus aborting cows, mean prolactin concentrations failed to differ on Days 40, 90, 120, 150 and 180 of pregnancy, whereas prolactin values were significantly lower (P=0.03) in aborting animals on Day 210 of pregnancy. Our results indicate that a positive photoperiod and Neospora-infection lead to increased plasma prolactin concentrations throughout gestation. Reduced prolactin concentrations detected in Neospora-seropositive aborting cows compared to non-aborting animals suggests a protective effect of prolactin in N. caninum infection.

Some factors affecting the abortion rate in dairy herds with high incidence of Neospora-associated abortions are different in cows and heifers

The aim of this study was to determine if the factors affecting the abortion rate in dairy herds with high incidence of Neospora-associated abortions are different in pregnancies of cows and heifers chronically infected with Neospora caninum. In heifers (n = 229), an increase in the cumulative number of days with a mean relative humidity (RH) lower than 60% during the second trimester of gestation increases the risk of abortion. Yet, the likelihood of abortion was 7.6 times lower for pregnant heifers inseminated with Limousin bull semen, compared with those inseminated with Holstein-Friesian bull semen. In pregnancies of parous cows (n = 521), an increase in rainfall and in the cumulative number of days with a mean RH lower than 60% during the second trimester of gestation increased the abortion rate. However, in contrast, an increase in the lactation number produced a decrease in the abortion rate, with a likelihood of abortion 4.8 times lower for pregnant cows inseminated with Limousin bull semen, and three times lower for those inseminated with Belgian Blue bull semen, compared with dairy cows inseminated with Holstein-Friesian bull semen. Finally, the likelihood of abortion was 3.2 times lower for pregnancies of parous cows with low antibody titres against N. caninum (6-30 units) as compared to those with high antibody titres (>/=30 units), whereas in heifers this variable had no effect. The practical recommendations of the present study include the control of the cow environment during the second trimester of gestation, the priority of culling for parous cows with higher antibody titres against N. caninum and the insemination of Neospora-seropositive cows with semen from the Limousin breed.

Spread-out Bragg peak and monitor units calculation with the Monte Carlo code MCNPX

The aim of this work was to study the dosimetric potential of the Monte Carlo code MCNPX applied to the protontherapy field. For series of clinical configurations a comparison between simulated and experimental data was carried out, using the proton beam line of the MEDICYC isochronous cyclotron installed in the Centre Antoine Lacassagne in Nice. The dosimetric quantities tested were depth-dose distributions, output factors, and monitor units. For each parameter, the simulation reproduced accurately the experiment, which attests the quality of the choices made both in the geometrical description and in the physics parameters for beam definition. These encouraging results enable us today to consider a simplification of quality control measurements in the future. Monitor Units calculation is planned to be carried out with preestablished Monte Carlo simulation data. The measurement, which was until now our main patient dose calibration system, will be progressively replaced by computation based on the MCNPX code. This determination of Monitor Units will be controlled by an independent semi-empirical calculation.

Plasma concentrations of pregnancy-associated glycoprotein-1 (PAG-1) in high producing dairy cows suffering early fetal loss during the warm season

The present study was designed to establish whether plasma pregnancy-associated glycoprotein-1 (PAG-1) measurements during the early fetal period can be associated with early fetal loss. Blood samples were obtained and ultrasound controls performed on days 35, 42, 49, 56, and 63 of gestation or until pregnancy loss from 98 lactating dairy cows. Radioimmunoassay systems were used to determine PAG-1 and progesterone concentrations. Of the 98 pregnancies investigated 18 (18.4%) suffered early fetal loss: 15 (18.5%) in cows carrying singletons, and 3 (16.7%) in twin pregnancies. In cows suffering pregnancy loss, all living embryos registered on day 35 seemed normal in size and development in all weekly ultrasound controls before fetal expulsion. Using analysis of variance, plasma PAG-1 and progesterone values were not different between no loss and fetal loss groups for every gestation period. Based on the odds ratio, and considering only PAG-1 values obtained on day 35 of gestation, the risk of fetal loss was 10 and 6.8 times more likely in cows with low (<2.5 ng/ml) and high (>4 ng/ml) PAG-1 values, respectively, than in cows with medium PAG-1 values, used as reference. Of the 10 inseminating bulls included in the study, one was related to increased fetal loss by odds ratio of 21.7, whereas one bull was attributed fetal loss rate reduced by odds ratio of 12.5 (1/0.08) These findings can have a clear clinical application: PAG-1 measurements from one single sample taken on day 35 of gestation provided more useful information than a series of values obtained from day 35 to 63 of gestation, and can be indicators of subsequent fetal loss.

Monte Carlo simulation of a medical linear accelerator for radiotherapy use

A Monte Carlo code MCNPX (Monte Carlo N-particle) was used to model a 25 MV photon beam from a PRIMUS (KD2-Siemens) medical linear electron accelerator at the Centre Antoine Lacassagne in Nice. The entire geometry including the accelerator head and the water phantom was simulated to calculate the dose profile and the relative depth-dose distribution. The measurements were done using an ionisation chamber in water for different square field ranges. The first results show that the mean electron beam energy is not 19 MeV as mentioned by Siemens. The adjustment between the Monte Carlo calculated and measured data is obtained when the mean electron beam energy is approximately 15 MeV. These encouraging results will permit to check calculation data given by the treatment planning system, especially for small fields in high gradient heterogeneous zones, typical for intensity modulated radiation therapy technique.

Thermoluminescence properties of CVD diamond for clinical dosimetry use

The application of diamond to dosimetry is desirable because of its tissue equivalence, chemical inertness and small size, but this has not been commercially viable owing to the non-reproducible response of natural diamond. The chemical vapour deposition (CVD) of diamond permits controlled, reproducible and large-scale production of this material at potentially low cost. An investigation of some clinically relevant features like the depth-dose distribution as well as the absorbed dose profile, obtained using thermoluminescence (TL), is reported for several CVD diamond films. The TL characterisation presented here shows that CVD diamond films should be excellent TL-mode detectors in instances of radiotherapy and in vivo radiation dosimetry.

The electron energy dependence of the TL response for CVD diamonds

The thermoluminescent (TL) response of CVD diamond is investigated after bombarding a sample with monoenergetic electrons (at 6 and 21 MeV). Irradiations are performed at room temperature with a medical linear electron accelerator PRIMUS (KD2-Siemens). The TL curve shows a peak at approximately 540 K. The area of this peak as a function of fluence exhibits saturation behaviour at high energies. Moreover, there is no significant difference between the TL response at 21 MeV electrons and that at 6 MeV. In order to explain these experimental results, calculations of the ionising dose have been performed with the code MCNPX (Monte Carlo N-Particle) for various incident energies from 0.1 MeV up to 100 MeV.

Monte Carlo simulation of a protontherapy platform devoted to ocular melanoma

Patients with ocular melanoma have been treated since June 1991 at the medical cyclotron of the Centre Antoine Lacassagne (CAL). Positions and sizes of the ocular nozzle elements were initially defined based on experimental work, taking as a pattern functional existing facilities. Nowadays Monte Carlo (MC) calculation offers a tool to refine this geometry by adjusting size and place of beam modeling devices. Moreover, the MC tool is a useful way to calculate the dose and to evaluate the impact of secondary particles in the field of radiotherapy or radiation protection. Both LINAC and cyclotron producing x rays, electrons, protons, and neutrons are available in CAL, which suggests choosing MCNPX for its particle versatility. As a first step, the existing installation was input in MCNPX to check its aptitude to reproduce experimentally measured depth-dose profile, lateral profile, output-factor (OF), and absolute dose. The geometry was defined precisely and described from the last achromatic bending magnet of our proton beam line to the position of treated eyes. Relative comparisons of percentage depth-dose and lateral profiles, performed between measured data and simulations, show an agreement of the order of 2% in dose and 0.1 mm in range accuracy. These comparisons, carried out with and without beam-modifying device, yield results compatible to the required precision in ocular melanoma treatments, as long as adequate choices are made on MCNPX input decks for physics card. Absolute dose and OF issued from calculations and measurements were also compared. Results obtained for these two kinds of data, carried out in the simplified situation of an unmodulated beam, indicate that MC calculation could effectively complement measurements. These encouraging results are a large source of motivation to promote further studies, first in a new design of the ocular nozzle, and second in the analysis of the influence of beam-modifying devices attached to the final patient collimator, such as wedge or compensators, on dose values.