Influence of magnetic field on a novel scintillation dosimeter in a 1.5 T MR-linac.

For commissioning and quality assurance for adaptive workflows on the MR-linac, a dosimeter which can measure time-resolved dose during MR image acquisition is desired. The Blue Physics model 10 scintillation dosimeter is potentially an ideal detector for such measurements. However, some detectors can be influenced by the magnetic field of the MR-linac. To assess the calibration methods and magnetic field dependency of the Blue Physics scintillator in the 1.5 T MR-linac. Several calibration methods were assessed for robustness. Detector characteristics and the influence of the calibration methods were assessed based on dose reproducibility, dose linearity, dose rate dependency, relative output factor (ROF), percentage depth dose profile, axial rotation and the radial detector orientation with respect to the magnetic field. The potential application of time-resolved dynamic dose measurements during MRI acquisition was assessed. A variation of calibration factors was observed for different calibration methods. Dose reproducibility, dose linearity and dose rate stability were all found to be within tolerance and were not significantly affected by different calibration methods. Measurements with the detector showed good correspondence with reference chambers. The ROF and radial orientation dependence measurements were influenced by the calibration method used. Axial detector dependence was assessed and relative readout differences of up to 2.5% were observed. A maximum readout difference of 10.8% was obtained when rotating the detector with respect to the magnetic field. Importantly, measurements with and without MR image acquisition were consistent for both static and dynamic situations. The Blue Physics scintillation detector is suitable for relative dosimetry in the 1.5 T MR-linac when measurements are within or close to calibration conditions.

Experimental validation of multi-fraction online adaptations in magnetic resonance guided radiotherapy.

Background and purpose: Radiotherapy plan verification is generally performed on the reference plan based on the pre-treatment anatomy. However, the introduction of online adaptive treatments demands a new approach, as plans are created daily on different anatomies. The aim of this study was to experimentally validate the accuracy of total doses of multi-fraction plan adaptations in magnetic resonance imaging guided radiotherapy in a phantom study, isolated from the uncertainty of deformable image registration. Materials and methods: We experimentally verified the total dose, measured on external beam therapy 3 (EBT3) film, using a treatment with five online adapted fractions. Three series of experiments were performed, each focusing on a category of inter-fractional variation; translations, rotations and body modifications. Variations were introduced during each fraction and adapted plans were generated and irradiated. Single fraction doses and total doses over five online adapted fractions were investigated. Results: The online adapted measurements and calculations showed a good agreement for single fractions and multi-fraction treatments for the dose profiles, gamma passing rates, dose deviations and distances to agreement. The gamma passing rate using a 2%/2 mm criterion ranged from 99.2% to 99.5% for a threshold dose of 10% of the maximum dose (Dmax) and from 96.2% to 100% for a threshold dose of 90% of Dmax, for the total translations, rotations and body modifications. Conclusions: The total doses of multi-fraction treatments showed similar accuracies compared to single fraction treatments, indicating an accurate dosimetric outcome of a multi-fraction treatment in adaptive magnetic resonance imaging guided radiotherapy.

Dosimetric evaluation of off-axis fields and angular transmission for the 1.5 T MR-linac.

Objective.GPU-oriented Monte Carlo dose (GPUMCD) is a fast dose calculation algorithm used for treatment planning on the Unity MR-linac. Treatments for the MR-linac must be calculated quickly and accurately, and must account for two important MR-linac aspects: off-axis positions and angular transmission through the cryostat, couch and MR-coils. Therefore, the aim of this research is to quantify the system-related errors for GPUMCD calculations over the range of clinically-relevant field configurations and gantry angles.Approach.Dose profiles (crossline, inline and PDD) were measured and calculated for varying field sizes, off-axis positions and depths. Eleven different (off-axis) positions were included. The angular transmission was investigated by measuring and calculating the transmission for multiple angles, taking the cryostat, couch and coils into account.Main results.Differences between absolute point doses were found to be within 1.7% for field sizes 2 × 2 cm2and larger. The relative dose profiles in the crossline, inline and PDD direction illustrated maximum mean dose differences of 0.9pp, 0.8pp and 0.7pp ofDmaxin the central region for field sizes 2 × 2 cm2and larger. The 1 × 1 cm2field size showed larger dosimetric errors for absolute point doses and relative dose profiles. The maximum mean DTA in the penumbra was 0.7 mm. The mean difference in angular transmission ranged from -0.33% ± 0.60% to 0.27% ± 0.91% using three treatment machines. Additionally, 77.1%-93.7% of the datapoints remained within 1% transmission difference. The largest transmission differences were present at the edges of the table.Significance.This research showed that the GPUMCD algorithm provides reliable dose calculations with a low uncertainty for field sizes 2 × 2 cm2and larger, focusing on off-axis fields and angular transmission.

Acceptance procedure for the linear accelerator component of the 1.5 T MRI-linac.

PURPOSE: To develop and implement an acceptance procedure for the new Elekta Unity 1.5 T MRI-linac. METHODS: Tests were adopted and, where necessary adapted, from AAPM TG106 and TG142, IEC 60976 and NCS 9 and NCS 22 guidelines. Adaptations were necessary because of the atypical maximum field size (57.4 × 22 cm), FFF beam, the non-rotating collimator, the absence of a light field, the presence of the 1.5 T magnetic field, restricted access to equipment within the bore, fixed vertical and lateral table position, and the need for MR image to MV treatment alignment. The performance specifications were set for stereotactic body radiotherapy (SBRT). RESULTS: The new procedure was performed similarly to that of a conventional kilovoltage x-ray (kV) image guided radiation therapy (IGRT) linac. Results were acquired for the first Unity system. CONCLUSIONS: A comprehensive set of tests was developed, described and implemented for the MRI-linac. The MRI-linac met safety requirements for patients and operators. The system delivered radiation very accurately with, for example a gantry rotation locus of isocenter of radius 0.38 mm and an average MLC absolute positional error of 0.29 mm, consistent with use for SBRT. Specifications for clinical introduction were met.

Micronutrient deficiencies in critical illness.

BACKGROUND & AIMS: Low micronutrient levels in critical illness have been reported in multiple studies. Because of the antioxidant properties of various micronutrients, micronutrient deficiency may augment oxidative stress in critical illness. However, it remains unclear whether micronutrient concentrations in ICU patients are different from those in healthy age-matched controls. It is also unclear whether micronutrient deficiency develops, worsens, or resolves during ICU admission without supplementation. METHODS: We prospectively studied a cohort of adult critically ill patients. Micronutrient levels, including selenium, ß-carotene, vitamin C, E, B1 and B6 were measured repeatedly during the first week of ICU admission. We compared the micronutrient concentrations at ICU admission to those of healthy age-matched controls. In addition, associations between micronutrient concentrations with severity of illness, inflammation and micronutrient intake were investigated. RESULTS: Micronutrient blood concentrations were obtained from 24 critically ill adults and 21 age-matched healthy controls. The mean micronutrient levels at admission in the ICU patients were: selenium 0.52 µmol/l, ß-carotene 0.17 µmol/l, vitamin C 21.5 µmol/l, vitamin E 20.3 µmol/l, vitamin B1 129.5 nmol/l and vitamin B6 41.0 nmol/l. In the healthy controls micronutrient levels of selenium (0.90 µmol/l), ß-carotene (0.50 µmol/l), vitamin C (45 µmol/l) and vitamin E (35.5 µmol/l) were significantly higher, while vitamin B1 (122 nmol/l) and B6 (44 nmol/l) were not significantly different between patients and controls. Selenium, vitamin B1 and vitamin B6 levels remained stable during ICU admission. Vitamin C levels dropped significantly until day 5 (p < 0.01). Vitamin E and ß-carotene levels increased significantly on days 5-7 and day 7, respectively (p < 0.01). Micronutrient levels were not associated with severity of illness, CRP or micronutrient intake during the admission. CONCLUSIONS: At admission, ICU patients already had lower plasma levels of selenium, ß-carotene, vitamin C and vitamin E than healthy controls. Vitamin C levels dropped significantly during the first days of ICU admission, while ß-carotene and vitamin E levels increased after 5-7 days. No association between micronutrient levels and severity of illness, C-reactive protein (CRP) or micronutrient intake was found. Progressive enteral tube feeding containing vitamins and trace elements does not normalize plasma levels in the first week of ICU stay. This was a hypothesis generating study and more investigation in a larger more diverse sample is needed.

Baby's first bites: Association between observed maternal feeding behavior and infant vegetable intake and liking.

Positive experiences with the introduction of solid food in infancy may lead to positive associations with feeding in both parent and infant. During this transitional period, parental feeding behavior and infant eating behavior might mutually reinforce each other. A feeding style that is found to be associated with positive child eating behavior, is sensitive feeding. In the present study we tested bidirectional prospective relations between mother and infant behavior in a cross-lagged model using observations of two feeds on two consecutive days on which the first bites of solid food were offered. The sample consisted of 246 first-time mothers and their infants, whose feeding interactions were videotaped during two home visits. Maternal sensitive feeding behavior (consisting of responsiveness to child feeding cues, general sensitivity and non-intrusiveness) and maternal positive and negative affect were coded. In addition, infant vegetable intake was weighed and vegetable liking was reported by mother. Results showed at least some stability of maternal feeding behavior and infant vegetable intake and liking from the first to the second feed. In addition, during the second feed maternal sensitive feeding and positive affect were associated with infant vegetable intake (r=.34 and r=.14) and liking (r=.33 and r=.39). These associations were mostly absent during the first feed. Finally, infant vegetable liking during the first feed positively predicted maternal sensitive feeding behavior during the second feed (ß=.25), suggesting that the infant's first response might influence maternal behavior. Taken together, mother and infant seem more attuned during the second feed than during the first feed. Future studies might include multiple observations over a longer time period, or micro-coding. Such insights can inform prevention programs focusing on optimizing feeding experiences during the weaning period.

Higher Levels of Physical Activity Are Associated with Greater Fruit and Vegetable intake in Older Adults.

OBJECTIVE: High levels of physical activity (PA) and optimal nutrition independently improve healthy aging, but few data are available about how PA may influence food preferences in older populations. Therefore, the aim of our study was to establish if there is an association between habitual PA and intake of nutrient-dense foods (i.e. fruits and vegetables). DESIGN: A cross-sectional survey was conducted. SETTING: The Netherlands. PARTICIPANTS: 2466 older adults (56% male, age 62±9 yr). MEASUREMENTS: PA was assessed using the short questionnaire to assess health (SQUASH) and participants were classified into quintiles of weekly PA (MET-h/wk). Total fruit and vegetable intake was assessed using a validated food frequency questionnaire (FFQ) and were corrected for energy intake (g/kcal/d) in the analyses. Multiple regression analyses were performed to determine the association between PA and fruit and vegetable intake, including covariates. RESULTS: Being in the higher quintiles of PA (Q3, Q4 and Q5) was positively associated with more daily fruit and vegetable consumption, even after correction for total energy intake (Q3; ß=0.089, P<0.001, Q4; ß=0.047, P=0.024, Q5; ß=0.098, P<0.001). CONCLUSIONS: Older adults who are moderately to highly physically active tend to consume more fruit and vegetable compared to less active peers, when corrected for total energy intake. Female gender, under- and overreporting dietary intake (Goldberg score), non-smoking, high level of education, less alcohol consumption and a lower body mass index positivity affected this relationship. Our data will help health-care professionals to accelerate their efforts to treat and prevent chronic diseases.

Detection of gluten in duplicate portions to determine gluten intake of coeliac disease patients on a gluten-free diet.

This study determined the gluten content of foods and meals consumed by coeliac disease (CD) patients who adhere to a gluten-free diet, and to estimate the total daily intake of gluten of these patients. CD patients fulfilling defined inclusion criteria were preselected and approached for participation in the study. Duplicate portions (DP) of foods and mixed dishes were collected from the CD patients for evaluating complete daily food intake during two individual days. Also, for these days, written food records were completed by the participants. From each DP, a laboratory sample was prepared and analysed for its gluten concentration and total daily gluten intake was calculated. Each individual's total daily intakes of energy and macronutrients were calculated using the Dutch food composition database. In total, twenty-seven CD patients participated, seven males and twenty females, aged between 21 and 64 years. In thirty-two (6 %) of 499 food samples collected in total, more than 3 mg/kg gluten was present. In four of these thirty-two samples, the gluten concentration was above the European legal limit of 20 mg/kg and three of the four samples had a gluten-free label. The maximal gluten intake was 3·3 mg gluten/d. The gluten tolerance for sensitive CD patients (>0·75 mg/d) was exceeded on at least six out of fifty-four study days. To also protect these sensitive CD patients, legal thresholds should be re-evaluated and the detection limit of analytical methods for gluten analysis lowered.

Relationship between intake and plasma concentrations of vitamin B12 and folate in 873 adults with a physically active lifestyle: a cross-sectional study.

BACKGROUND: Vitamin B12 and folate function as co-factors in pathways used during physical activity. Physical activity may therefore increase vitamin requirements, leading to a risk of deficient plasma concentrations. We aimed to investigate the relationship between intake and plasma concentrations of vitamin B12 and folate in physically active adults, as well as identify other determinants of vitamin B12 and folate plasma concentrations. METHODS: The study population consisted of 873 adults (528 men and 345 women), aged 19-78 years, who participated in a 4-day walking event. The relationship between intake and plasma concentrations of vitamin B12 and folate was assessed using correlation and linear regression analyses. In addition, potential other determinants (sex, age, body mass index, energy intake and physical activity) of vitamin plasma concentrations were investigated. RESULTS: Significant positive correlations were observed between intake and plasma concentrations of vitamin B12 [Pearson's correlation coefficient = 0.15; 95% confidence interval (CI) = 0.08-0.21] and folate (Pearson's correlation coefficient = 0.18; 95% CI = 0.12-0.25). In addition to vitamin intake, sex, age and energy intake were also determinants of both vitamin B12 and folate plasma concentrations in multivariable regression models. CONCLUSIONS: The results suggest a positive association between intake and plasma concentrations for both vitamin B12 and folate in physically active people. By contrast to our hypothesis, physical activity was not a determinant of vitamin B12 and folate plasma concentrations. However, sex, age and energy intake were found to be determinants. Thus, when studying the relationship between intake and plasma concentrations of vitamin B12 or folate, these factors should be taken into account.

Changes in body composition during and after adjuvant or neo-adjuvant chemotherapy in women with breast cancer stage I-IIIB compared with changes over a similar timeframe in women without cancer.

PURPOSE: Body weight and body composition may change during and after adjuvant or neo-adjuvant chemotherapy for breast cancer. However, most studies did not include a comparison group of women without cancer, thus could not assess whether observed changes differed from age-related fluctuations in body weight and body composition over time. We assessed changes in body composition during and after chemotherapy in breast cancer patients compared with age-matched women not diagnosed with cancer. METHODS: We recruited 181 patients with stage I-IIIb breast cancer and 180 women without cancer. In patients, we assessed body composition using a dual-energy X-ray scan before start of chemotherapy (T1), shortly after chemotherapy (T2), and 6 months after chemotherapy (T3); for the comparison group, the corresponding time points were recruitment (T1) and 6 (T2) and 12 (T3) months. RESULTS: Fifteen percent of patients and 8% of the comparison group gained at least 5% in body weight between T1 and T3. Among the comparison group, no statistically significant changes in body weight, or body composition were observed over time. Body weight of patients significantly increased from baseline (72.1 kg ± 0.4 kg) to T2 (73.3 kg ± 0.4 kg), but decreased to 73.0 kg ± 0.4 kg after chemotherapy (T3). Lean mass of patients significantly increased from 43.1 kg ± 0.5 kg at baseline to 44.0 kg ± 0.5 kg at T2, but returned to 43.1 kg ± 0.5 kg at T3. There were no differential changes in fat mass over time between patients and the comparison group. CONCLUSIONS: Changes in body weight and body composition during and after chemotherapy for early stage breast cancer were modest, and did not differ substantially from changes in body weight and body composition among women without cancer.

Systematic review of functional outcome and quality of life after total pancreatectomy.

BACKGROUND: Surgeons have traditionally been reluctant to perform total pancreatectomy because of concerns for brittle diabetes and poor quality of life (QoL). Several recent studies have suggested that outcomes following total pancreatectomy have improved, but a systematic review is lacking. METHODS: A systematic review was undertaken of studies reporting on outcomes after total pancreatectomy for all indications, except chronic pancreatitis. PubMed, EMBASE (Ovid), and Cochrane Library were searched (2005-2018). Endpoints included functional outcome and QoL. RESULTS: A total of 21 studies, including 1536 patients, fulfilled the eligibility criteria. During a median follow-up of 20·8 (range 1·5-96·0) months, 18·6 per cent (45 of 242 patients) were readmitted for endocrine-related morbidity, with associated mortality in 1·6 per cent (6 of 365 patients). No diabetes-related mortality was reported in studies including only patients treated after 2005. Symptoms related to exocrine insufficiency were reported by 43·5 per cent (143 of 329 patients) during a median follow-up of 15·9 (1·5-96·0) months. Overall QoL, reported by 102 patients with a median follow-up of 28·6 (6·0-66·0) months, using the EORTC QLQ-C30 questionnaire, showed a moderately reduced summary score of 76 per cent, compared with a general population score of 86 per cent (P = 0·004). CONCLUSION: Overall QoL after total pancreatectomy is affected adversely, in particular by the considerable impact of diarrhoea that requires better treatment. There is also room for improvement in the management of diabetes after total pancreatectomy, particularly with regards to prevention of diabetes-related morbidity.

ANTECEDENTES: Los cirujanos tradicionalmente se han mostrado reacios a realizar una pancreatectomía total (total pancreatectomy, TP) debido a la preocupación por la aparición de diabetes lábil y la mala calidad de vida (quality of life, QoL). Varios estudios recientes han sugerido que el resultado de la TP ha mejorado, sin embargo no existe una revisión sistemática. MÉTODOS: Se ha realizado una revisión sistemática de los estudios que incluían los resultados después de una TP efectuada para todas las indicaciones, excepto para una pancreatitis crónica. Se realizaron búsquedas en PubMed, Embase (Ovid) y Cochrane Library (2005-2018). Los resultados principales eran el resultado funcional y la calidad de vida. RESULTADOS: En total, 21 estudios cumplieron los criterios de elegibilidad, incluyendo 1.536 pacientes que se habían sometido a una TP. Durante una mediana de seguimiento de 20,8 meses (rango 1,5-96,0), el 18,6% de los pacientes (45 de 242) fueron reingresados por morbilidad relacionada con la función endocrina, con una mortalidad asociada del 1,6% (6 de 365 pacientes). No hubo mortalidad relacionada con la diabetes en los estudios que incluyeron solo aquellos pacientes tratados después de 2005. Se observaron síntomas relacionados con insuficiencia exocrina en un 43,5% de los pacientes (143 de 329) durante una mediana de seguimiento de 15,9 meses (rango 1,5-96,0). La calidad de vida global, informada para 102 pacientes con una mediana de seguimiento de 28,6 meses (rango 6,0-66,0) utilizando el cuestionario EORTC QLQ-C30, mostró una puntuación sumatoria moderadamente reducida del 76% en comparación con la puntuación del 86% para la población general (P = 0,004). CONCLUSIÓN: Es necesario seguir mejorando el manejo de la diabetes después de la TP, sobre todo en lo que respecta a la prevención de la morbilidad relacionada con la diabetes. La calidad de vida global se ve afectada después de la TP y, especialmente, el impacto de la diarrea es considerable y requiere mejorar este aspecto en el futuro.

Baby's first bites: a randomized controlled trial to assess the effects of vegetable-exposure and sensitive feeding on vegetable acceptance, eating behavior and weight gain in infants and toddlers.

BACKGROUND: The start of complementary feeding in infancy plays an essential role in promoting healthy eating habits. Evidence shows that it is important what infants are offered during this first introduction of solid foods: e.g. starting exclusively with vegetables is more successful for vegetable acceptance than starting with fruits. How infants are introduced to solid foods also matters: if parents are sensitive and responsive to infant cues during feeding, this may promote self-regulation of energy intake and a healthy weight. However, the effectiveness of the what and the how of complementary feeding has never been experimentally tested in the same study. In the current project the what and how (and their combination) are tested in one study to determine their relative importance for fostering vegetable acceptance and self-regulation of energy intake in infants. METHODS: A four-arm randomized controlled trial (Baby's First Bites (BFB)) was designed for 240 first-time Dutch mothers and their infants, 60 per arm. In this trial, we compare the effectiveness of (a) a vegetable-exposure intervention focusing on the what in complementary feeding; (b) a sensitive feeding intervention focusing on the how in complementary feeding, (c) a combined intervention focusing on the what and how in complementary feeding; (d) an attention-control group. All mothers participate in five sessions spread over the first year of eating solid foods (child age 4-16 months). Primary outcomes are vegetable consumption, vegetable liking and self-regulation of energy intake. Secondary outcomes are child eating behaviors, child anthropometrics and maternal feeding behavior. Outcomes are assessed before, during and directly after the interventions (child age 18 months), and when children are 24 and 36 months old. DISCUSSION: The outcomes are expected to assess the impact of the interventions and provide new insights into the mechanisms underlying the development of vegetable acceptance, self-regulation and healthy eating patterns in infants and toddlers, as well as the prevention of overweight. The results may be used to improve current dietary advice given to parents of their young children on complementary feeding. TRIAL REGISTRATION: The trial was retrospectively registered during inclusion of participants at the Netherlands National Trial Register (identifier NTR6572 ) and at ClinicalTrials.gov ( NCT03348176 ). Protocol issue date: 1 April 2018; version number 1.

A longitudinal mixed methods study on changes in body weight, body composition, and lifestyle in breast cancer patients during chemotherapy and in a comparison group of women without cancer: study protocol.

BACKGROUND: More than 60% of women diagnosed with early stage breast cancer receive (neo)adjuvant chemotherapy. Breast cancer patients receiving chemotherapy often experience symptoms such as nausea, vomiting and loss of appetite that potentially affect body weight and body composition. Changes in body weight and body composition may detrimentally affect their quality of life, and could potentially increase the risk of disease recurrence, cardiovascular disease and diabetes. To date, from existing single method (quantitative or qualitative) studies is not clear whether changes in body weight and body composition in breast cancer patients are treatment related because previous studies have not included a control group of women without breast cancer. METHODS: We therefore developed the COBRA-study (Change Of Body composition in BReast cancer: All-in Assessment-study) to assess changes in body weight, body composition and related lifestyle factors such as changes in physical activity, dietary intake and other behaviours. Important and unique features of the COBRA-study is that it used I) a "Mixed Methods Design", in order to quantitatively assess changes in body weight, body composition and lifestyle factors and, to qualitatively assess how perceptions of women may have influenced these measured changes pre-, during and post-chemotherapy, and II) a control group of non-cancer women for comparison. Descriptive statistics on individual quantitative data were combined with results from a thematic analysis on the interviews- and focus group data to understand patients' experiences before, during and after chemotherapy. DISCUSSION: The findings of our mixed methods study, on chemotherapy treated cancer patients and a comparison group, can enable healthcare researchers and professionals to develop tailored intervention schemes to help breast cancer patients prevent or handle the physical and mental changes they experience as a result of their chemotherapy. This will ultimately improve their quality of life and could potentially reduce their risk for other co-morbidity health issues such as cardiovascular disease and diabetes.

Insufficient Protein Intakes is Highly Prevalent among Physically Active Elderly.

OBJECTIVES: Sufficient protein intake and habitual physical activity are key factors in the prevention and treatment of sarcopenia. In the present study, we assessed habitual dietary protein intake and the contribution of animal proteins in male versus female physically active elderly and identified determinants of protein intake. DESIGN: a cross-sectional study. SETTING: the study was performed within the Nijmegen Exercise Study. PARTICIPANTS: physically active elderly ≥ 65 yrs. MEASUREMENTS: Physical activity was assessed using the SQUASH questionnaire and expressed in Metabolic Equivalent of Task hours per week (METhr/wk). Dietary protein intake was determined using a validated food frequency questionnaire (FFQ). Multivariate linear regression analysis was used to determine whether age, sex, educational level, smoking, alcohol intake and physical activity were associated with protein intake (g/kg/d). RESULTS: A total of 910 participants (70±4 yrs, 70% male) were included and reported a habitual physical activity level of 85.0±53.5 METhr/wk. Protein intake was 1.1±0.3 g/kg/d with 57% animal-based proteins for males, and 1.2±0.3 g/kg/d with 59% animalbased proteins for females (both P<0.05). In total, 16%, 42% and 67% of the male elderly and 10%, 34% and 56% of the female elderly did not meet the recommended protein intake of 0.8, 1.0 and 1.2 g/kg/d, respectively. Female sex (ß=0.055, P=0.036) and more physical activity (ß=0.001, P=0.001) were associated with a higher daily protein intake (g/kg/d). CONCLUSION: The majority of physically active elderly and in particular males (i.e. 67%) does not reach a protein intake of 1.2 g/kg/d, which may offset the health benefits of an active lifestyle on muscle synthesis and prevention of sarcopenia. Intervention studies are warranted to assess whether protein supplementation may enhance muscle mass and strength in physically active elderly.

Telemonitoring to improve nutritional status in community-dwelling elderly: design and methods for process and effect evaluation of a non-randomized controlled trial.

BACKGROUND: A good nutritional status is key for maintaining health and quality of life in older adults. In the Netherlands, 11 to 35% of the community-dwelling elderly are undernourished. Undernutrition or the risk of it should be signalled as soon as possible to be able to intervene at an early stage. However, in the context of an ageing population health care resources are scarce, evoking interest in health enabling technologies such as telemonitoring. This article describes the design of an intervention study focussing at telemonitoring and improving nutritional status of community-dwelling elderly. METHODS: The PhysioDom Home Dietary Intake Monitoring intervention was evaluated using a parallel arm pre-test post-test design including 215 Dutch community-dwelling elderly aged > 65 years. The six-month intervention included nutritional telemonitoring, television messages, and dietary advice by a nurse or a dietician. The control group received usual care. Measurements were performed at baseline, after 4.5 months, and at the end of the study, and included the primary outcome nutritional status and secondary outcomes behavioural determinants, diet quality, appetite, body weight, physical activity, physical functioning, and quality of life. Furthermore, a process evaluation was conducted to provide insight into intervention delivery, feasibility, and acceptability. DISCUSSION: This study will improve insight into feasibility and effectiveness of telemonitoring of nutritional parameters in community-dwelling elderly. This will provide relevant insights for health care professionals, researchers, and policy makers. TRIAL REGISTRATION: The study was retrospectively registered at Clinical-Trials.gov (identifier NCT03240094 ) since August 3, 2017.

Beam characterisation of the 1.5 T MRI-linac.

As a prerequisite for clinical treatments it was necessary to characterize the Elekta 1.5 T MRI-linac 7 MV FFF radiation beam. Following acceptance testing, beam characterization data were acquired with Semiflex 3D (PTW 31021), microDiamond (PTW 60019), and Farmer-type (PTW 30013 and IBA FC65-G) detectors in an Elekta 3D scanning water phantom and a PTW 1D water phantom. EBT3 Gafchromic film and ion chamber measurements in a buildup cap were also used. Special consideration was given to scan offsets, detector effective points of measurement and avoiding air gaps. Machine performance has been verified and the system satisfied the relevant beam requirements of IEC60976. Beam data were acquired for field sizes between 1 × 1 and 57 × 22 cm2. New techniques were developed to measure percentage depth dose (PDD) curves including the electron return effect at beam exit, which exhibits an electron-type practical range of 1.2 ± 0.1 cm. The Lorentz force acting on the secondary charged particles creates an asymmetry in the crossline profiles with an average shift of +0.24 cm. For a 10 × 10 cm2 beam, scatter from the cryostat contributes 1% of the dose at isocentre. This affects the relative output factors, scatter factors and beam profiles, both in-field and out-of-field. The average 20%-80% penumbral width measured for small fields with a microDiamond detector at 10 cm depth is 0.50 cm. MRI-linac penumbral widths are very similar to that of the Elekta Agility linac MLC, as is the near-surface dose PDD(0.2 cm) = 57%. The entrance surface dose is ∼36% of Dmax. Cryostat transmission is quantified for inclusion within the treatment planning system. As a result, the 1.5 T MRI-linac 7 MV FFF beam has been characterised for the first time and is suitable for clinical use. This was a key step towards the first clinical treatments with the MRI-linac, which were delivered at University Medical Center Utrecht in May 2017 (Raaymakers et al 2017 Phys. Med. Biol. 62 L41-50).

Characterization of a prototype MR-compatible Delta4 QA system in a 1.5 tesla MR-linac.

To perform patient plan quality assurance (QA) on a newly installed MR-linac (MRL) it is necessary to have an MR-compatible QA device. An MR compatible device (MR-Delta4) has been developed together with Scandidos AB (Uppsala, Sweden). The basic characteristics of the detector response, such as short-term reproducibility, dose linearity, field size dependency, dose rate dependency, dose-per-pulse dependency and angular dependency, were investigated for the clinical Delta4-PT as well as for the MR compatible version. All tests were performed with both devices on a conventional linac and the MR compatible device was tested on the MRL as well. No statistically significant differences were found in the short-term reproducibility (<0.1%), dose linearity (⩽0.5%), field size dependency (<2.0% for field sizes larger than 5 × 5 cm2), dose rate dependency (<1.0%) or angular dependency for any phantom/linac combination. The dose-per-pulse dependency (<0.8%) was found to be significantly different between the two devices. This difference can be explained by the fact that the diodes in the clinical Delta4-PT were irradiated with a much larger dose than the MR-Delta4-PT ones. The absolute difference between the devices (<0.5%) was found to be small, so no clinical impact is expected. For both devices, the results were consistent with the characteristics of the Delta4-PT device reported in the literature (Bedford et al 2009 Phys. Med. Biol. 54 N167-76; Sadagopan et al 2009 J. Appl. Clin. Med. Phys. 10 2928). We found that the characteristics of the MR compatible Delta4 phantom were found to be comparable to the clinically used one. Also, the found characteristics do not differ from the previously reported characteristics of the commercially available non-MR compatible Delta4-PT phantom. Therefore, the MR compatible Delta4 prototype was found to be safe and effective for use in the 1.5 tesla magnetic field of the Elekta MR-linac.

Performance of a PTW 60019 microDiamond detector in a 1.5 T MRI-linac.

Accurate small-field dosimetry is critical for a magnetic resonance linac (MRI-linac). The PTW 60019 microDiamond is close to an ideal detector for small field dosimetry due to its small physical size, high signal-to-noise ratio and approximate water equivalence. It is important to fully characterise the performance of the detector in a 1.5 T magnetic field prior to its use for MRI-linac commissioning and quality assurance. Standard techniques of detector testing have been implemented, or adapted where necessary to suit the capabilities of the MRI-linac. Detector warmup, constancy, dose linearity, dose rate linearity, field size dependence and leakage were within tolerance. Measurements with the detector were consistent with ion chamber measurements for medium sized fields. The effective point of measurement of the detector when used within a 1.5 T magnetic field was determined to be 0.80 ± 0.23 mm below the top surface of the device, consistent with the existing vendor recommendation and alignment mark at 1.0 mm. The angular dependence was assessed. Variations of up to 9.7% were observed, which are significantly greater than in a 0 T environment. Within the expected range of use, the maximum effect is approximately 0.6% which is within tolerance. However for large beams within a magnetic field, the divergence and consequent variation in angle of photon incidence means that the microDiamond would not be ideal for characterising the profiles and it would not be suitable for determining large-field beam parameters such as symmetry. It would also require a correction factor prior to use for patient-specific QA measurements where radiation is delivered from different gantry angles. The results of this study demonstrate that the PTW 60019 microDiamond detector is suitable for measuring small radiation fields within a 1.5 T magnetic field and thus is suitable for use in MRI-linac commissioning and quality assurance.

Weight change during chemotherapy in breast cancer patients: a meta-analysis.

BACKGROUND: Weight gain during chemotherapy in women with breast cancer is commonly reported. However, there are important differences between studies that examined weight change during chemotherapy; e.g. type of chemotherapy, menopausal status, time between body weight measurements and sample size. The purpose of this meta-analysis was to quantify changes in body weight during chemotherapy for women with breast cancer, taking these differences into account. METHODS: We identified relevant studies using PubMed, Scopus and Embase databases. The search was limited to human studies published in English up to and including December 2015. Only studies among women with early stage breast cancer treated with chemotherapy, with reported body weight before and after chemotherapy and type of chemotherapy were included. Random-effect models were used, and heterogeneity between studies was explored through stratified analyses and meta-regression. Sensitivity analyses were done to explore whether a specific study markedly affected the results. RESULTS: In total 25 papers were found, including data from 2620 women. Overall, body weight increased during chemotherapy: 2.7 kg (95% CI 2.0, 7.5) with a high degree of heterogeneity (I2 = 94.2%). Stratified analyses showed weight gain in all strata, but did not substantially reduce heterogeneity. Univariate meta-regression showed less weight gain in prospective studies compared to chart review studies (-2.0, 95% CI: -3.1, -0.8). Studies including cyclophosphamide, methotrexate and 5-fluorouracil (CMF) regimes showed a greater weight gain compared to those that did not (2.2, 95% CI: 1.1, 3.3); and papers published until the year 2000 showed a greater weight gain compared to those published after 2000 (1.9, 95% CI:-0.8, 3.1). In the multivariate models only studies including CMF regimes and studies published until 2000 were associated with significant weight gain of respectively 1.3 and 1.4 kg. CONCLUSION: Despite the high heterogeneity, this meta-analysis shows significant weight gain during chemotherapy for women with breast cancer. Weight gain was more pronounced in papers published until 2000 and women receiving CMF as chemotherapy regime. Although weight gain after chemotherapy has decreased over the course of time, weight gain is still substantial and deserves clinical attention.

Differences in dietary intake during chemotherapy in breast cancer patients compared to women without cancer.

PURPOSE: Breast cancer patients receiving chemotherapy often experience symptoms such as nausea, vomiting and loss of appetite that potentially affect dietary habits. This study assessed the intake of energy, macronutrients and food groups before and during chemotherapy in breast cancer patients compared with women without cancer, and determined the association between symptoms and energy and macronutrient intake. METHODS: This study included 117 newly diagnosed breast cancer patients scheduled for chemotherapy and 88 women without cancer. Habitual intake before chemotherapy was assessed with a food frequency questionnaire. Two 24-h dietary recalls were completed on random days for each participant during the whole chemotherapy treatment for patients and within 6 months after recruitment for women without cancer. Shortly, after the dietary recall, participants filled out questionnaires on symptoms. RESULTS: Before chemotherapy, habitual energy and macronutrient intake was similar for breast cancer patients and women without cancer. During chemotherapy, breast cancer patients reported a significantly lower total energy, fat, protein and alcohol intake than women without cancer, as shown by a lower intake of pastry and biscuits, cheese, legumes and meat products. A decline in subjective taste perception, appetite and hunger and experiencing a dry mouth, difficulty chewing, lack of energy and nausea were associated with a lower energy intake. CONCLUSIONS: Symptoms induced by chemotherapy are associated with lower dietary intake and manifested by a lower intake of specific food groups. To ensure an optimal dietary intake during chemotherapy, it is important to monitor nutritional status and symptom burden during chemotherapy in breast cancer patients.