A filtering approach for PET and PG predictions in a proton treatment planning system

Positron emission tomography (PET) and prompt gamma (PG) detection are promising proton therapy monitoring modalities. Fast calculation of the expected distributions is desirable for comparison to measurements and to develop/train algorithms for automatic treatment error detection. A filtering formalism was used for positron-emitter predictions and adapted to allow for its use for the beamline of any proton therapy centre. A novel approach based on a filtering formalism was developed for the prediction of energy-resolved PG distributions for arbitrary tissues. The method estimates PG yields and their energy spectra in the entire treatment field. Both approaches were implemented in a research version of the RayStation treatment planning system. The method was validated against PET monitoring data and Monte Carlo simulations for four patients treated with scanned proton beams. Longitudinal shifts between profiles from analytical and Monte Carlo calculations were within -1.7 and 0.9 mm, with maximum standard deviation of 0.9 mm and 1.1 mm, for positron-emitters and PG shifts, respectively. Normalized mean absolute errors were within 1.2 and 5.3%. When comparing measured and predicted PET data, the same more complex case yielded an average shift of 3 mm, while all other cases were below absolute average shifts of 1.1 mm. Normalized mean absolute errors were below 7.2% for all cases. A novel solution to predict positron-emitter and PG distributions in a treatment planning system is proposed, enabling calculation times of only a few seconds to minutes for entire patient cases, which is suitable for integration in daily clinical routine.

Calculated beam quality correction factors for ionization chambers in MV photon beams

The beam quality correction factor, [Formula: see text], which corrects for the difference in the ionization chamber response between the reference and clinical beam quality, is an integral part of radiation therapy dosimetry. The uncertainty of [Formula: see text] is one of the most significant sources of uncertainty in the dose determination. To improve the accuracy of available [Formula: see text] data, four partners calculated [Formula: see text] factors for 10 ionization chamber models in linear accelerator beams with accelerator voltages ranging from 6 MV to 25 MV, including flattening-filter-free (FFF) beams. The software used in the calculations were EGSnrc and PENELOPE, and the ICRU report 90 cross section data for water and graphite were included in the simulations. Volume averaging correction factors were calculated to correct for the dose averaging in the chamber cavities. A comparison calculation between partners showed a good agreement, as did comparison with literature. The [Formula: see text] values from TRS-398 were higher than our values for each chamber where data was available. The [Formula: see text] values for the FFF beams did not follow the same [Formula: see text], [Formula: see text] relation as beams with flattening filter (values for 10 MV FFF beams were below fits made to other data on average by 0.3%), although our FFF sources were only for Varian linacs.

Evolution of the use of antioxidants in anti-ageing cosmetics

OBJECTIVE

Skin health and beauty are a cornerstone of general well-being in humans. Anti-ageing cosmetics are used to provide a healthy and youthful appearance. Among the different cosmetic actives, antioxidants are incorporated in anti-ageing products due to their beneficial effects in preventing and minimizing the signs of skin ageing. This work aims to understand how anti-ageing formulations changed in the past 7 years regarding pure antioxidants composition.

METHODS

Data were collected from anti-ageing formulations commercialized in main stores and pharmacies in the Portuguese market. The study started on 2011 and was updated with products launched or whose composition has been renewed on 2013, 2015 or 2018.

RESULTS

Ascorbic acid and tocopherol and their derivatives were consistently the most used antioxidants in anti-ageing formulations; followed by niacinamide and retinyl palmitate. Seven ascorbic acid derivatives are currently used in anti-ageing formulations while only three tocopherol derivatives were identified in this study. Several combinations of antioxidants were routinely found, mainly tocopherol (or tocopherol derivatives) with other antioxidants and tocopherol with tocopherol derivatives. We have not identified emerging antioxidants with great impact in anti-ageing formulations even though niacinamide and retinyl palmitate exhibited over 10% more usage in 2018.

CONCLUSION

This insight is relevant to the cosmetic industry providing a better understanding of the scientific-based formulation of modern cosmetics and supports the need for innovative antioxidants in anti-ageing cosmetics.

An international update of the EORTC questionnaire for assessing quality of life in breast cancer patients: EORTC QLQ-BR45

BACKGROUND

The European Organization for Research and Treatment of Cancer (EORTC) QLQ-BR23 was one of the first disease-specific questionnaires developed in 1996 to assess quality of life (QoL) in patients with breast cancer (BC). However, since 1996 major changes in BC treatment have occurred, requiring an update of the EORTC BC module. This study presents the results of the phase I-III update of the QLQ-BR23 questionnaire.

PATIENTS AND METHODS

The update of the EORTC QLQ-BR23 module followed standard EORTC guidelines. A systematic literature review revealed 83 potential relevant QoL issues during phases I and II. After shortening the issues list and following interviews with patients and health care providers, 15 relevant issues were transformed into 27 items. The preliminary module was pretested in an international, multicentre phase III study to identify and solve potential problems with wording comprehensibility and acceptability of the items. Descriptive statistics are provided. Analyses were qualitative and quantitative. We provide a psychometric structure of the items.

RESULTS

The phase I and II results indicated the need to supplement the original QLQ-BR23 with additional items related to newer therapeutic options. The phase III study recruited a total of 250 patients (from 12 countries). The final updated phase III module contains a total of 45 items: 23 items from the QLQ-BR23 and 22 new items. The new items contain two multi-item scales: a target symptom scale and a satisfaction scale. The target symptom scale can be divided into three subscales: endocrine therapy, endocrine sexual and skin/mucosa scale.

CONCLUSION

Our work has led to the development of a new EORTC QLQ-BR45 module that provides a more accurate and comprehensive assessment of the impact of new and scalable treatments on patients' QoL. The final version of the EORTC QLQ-BR45 is currently available for use in clinical practice. The final phase IV study is underway to confirm psychometric properties of the module.

Inequalities in the participation and outcomes of breast cancer screening programs in Valencia, Spain

Background

Breast cancer remains the most frequent tumour and first cancer related cause of death in the Valencian Community. Despite most of the population being aware of the existence of breast cancer screening programs (BCSP), there are great differences in uptake that are likely attributed to social determinants. The objective of this study, alligning with SDGs 3 and 10, is to assess inequalities in breast cancer screening uptake, diagnosis and treatment delay in the city of Valencia.

Methods

The population of study included 128 123 women invited to participate in the BCSP in the city of Valencia between 2014 and 2016. Uptake, diagnosis and treatment delay were assessed as outcomes. Covariates included country of origin, education level, size of family unit, risk of vulnerability, age, presence of disability, assigned health department and a social deprivation index. Bivariate analysis and logistic regression models were performed for each independent variable.

Results

BCSP uptake was of 63,8% with a diagnostic rate of 5,36‰. 76,7% of patients were below the 75th percentile of delay between diagnosis and treatment (52 days). Statistically significant relationships were found between uptake of BCSP and all studied covariates both in the bivariate analysis and regression model. Presence of disability, family unit size, age and health department had a statistically significant relationship with diagnosis in the bivariate analysis, of which only one health department and the social deprivation index’s second quintile remained significant in the regression model. No significant relations were found between treatment delay and any of the covariates.

Conclusions

Strong inequalities in the BCSP have been identified. Influencing factors must be targeted so as to ensure an egalitarian access to BCSP. Given its multifactorial nature, simple analyses must be avoided in the study of inequalities in breast cancer diagnosis. Data on lifestyle may contribute to future models.

Key messages

Social determinants continue to have an impact in the uptake of breast cancer screening programs in the city of Valencia. The assessment of inequalities in breast cancer diagnosis cannot be approached uniquely through the analysis of social determinants and may Benefit from the inclusion of data on lifestyle choices.

Prediction of positron emitter distributions for range monitoring in carbon ion therapy: an analytical approach

Range verification is one of the most relevant tasks in ion beam therapy. In the case of carbon ion therapy, positron emission tomography (PET) is the most widely used method for this purpose, which images the [Formula: see text]-activation following nuclear interactions of the ions with the tissue nuclei. Since the positron emitter activity profile is not directly proportional to the dose distribution, until today only its comparison to a prediction of the PET profile allows for treatment verification. Usually, this prediction is obtained from time-consuming Monte Carlo simulations of high computational effort, which impacts the clinical workflow. To solve this issue in proton therapy, a convolution approach was suggested to predict positron emitter activity profiles from depth dose distributions analytically. In this work, we introduce an approach to predict positron emitter distributions from depth dose profiles in carbon ion therapy. While the distal fall-off position of the positron emitter profile is predicted from a convolution approach similar to the one suggested for protons, additional analytical functions are introduced to describe the characteristics of the positron emitter distribution in tissue. The feasibility of this approach is demonstrated with monoenergetic depth dose profiles and spread out Bragg peaks in homogeneous and heterogeneous phantoms. In all cases, the positron emitter profile is predicted with high precision and the distal fall-off position is reproduced with millimeter accuracy.

Potential of synthetic chalcone derivatives to prevent marine biofouling

Biofouling represents a major economic, environmental and health concern for which new eco-friendly solutions are needed. International legislation has restricted the use of biocidal-based antifouling coatings, and increasing efforts have been applied in the search for environmentally friendly antifouling agents. This research work deals with the assessment of the interest of a series of synthetic chalcone derivatives for antifouling applications. Sixteen chalcone derivatives were synthesized with moderate yields (38-85%). Antifouling bioactivity of these compounds was assessed at different levels of biological organization using both anti-macrofouling and anti-microfouling bioassays, namely an anti-settlement assay using mussel (Mytilus galloprovincialis) larvae, as well as marine bacteria and microalgal biofilms growth inhibition bioassays. Results showed that three compounds (11, 12, and 16) were particularly active against the settlement of mussel larvae (EC₅₀ 7.24-34.63 μM), being compounds 12 and 16 also able to inhibit the growth of microfouling species (EC₅₀ 4.09-20.31 μM). Moreover, the most potent compounds 12 and 16 were found to be non-toxic to the non-target species Artemia salina (<10% mortality at 25 μM). A quantitative structure-activity relationship model predicted that descriptors describing the ability of molecules to form hydrogen bonds and encoding the shape, branching ratio and constitutional diversity of the molecule were implied in the antifouling activity against the settlement of mussel larvae. This work elucidates for the first time the relevance of synthesizing chalcone derivatives to generate new non-toxic products to prevent marine biofouling.