Determination of soluble tumor necrosis factor receptor II and secretory immunoglobulin A in saliva of patients with dementia.

The prevalence of pain and dementia increases with age, affecting a significant percentage of the population due to aging. Both pathologies are connected through the inflammatory process, specifically through the tumor necrosis factor. The effect of this cytokine is mediated through the modulation of its TNFRI and TNFRII receptors, which are linked to the dementia process. In addition, immunoglobulins such as secretory immunoglobulin A (sIgA) have been recognized as one of the main biomarkers of pain in saliva. sTNFRII and sIgA levels were determined in saliva samples by ELISA from healthy people and patients with dementia in GDS stages 5-7. The concentrations of these markers were also correlated with the GDS stage and sex. We observed a significant decrease (*** p ≤ 0.001) in the levels of sTNFRII (pg/mL) and a significant increase (** p ≤ 0.01) in the levels of sIgA (ng/mL) in the saliva of patients with dementia compared to the healthy control group. We did not observe a correlation with the data of the biomarkers regarding the GDS stage and sex. The results obtained for sTNFRII are consistent with those obtained by other authors on brain tissue, who conclude that unopposed neuronal TNFRI signaling, when TNFRII is selectively downregulated, leads to a more severe course of AD pathogenesis. Regarding sIgA, the elevated values of sIgA may reflect the immune status of these patients. Therefore, these biomarkers can provide us with relevant information through a non-invasive method such as saliva analysis.

Melting Temperature Depression of Polymer Single Crystals: Application to the Eco-Design of Tie-Layers in Polyolefinic-Based Multilayered Films.

In this paper, we describe a method for determining polymer compatibility, which will aid in establishing the requirements of polyolefinic materials for the eco-design of multilayer films for mechanical recycling while avoiding the use of reactive tie layers. Our ultimate goal is to define the molecular characteristics of the polyolefinic structural layer that improve compatibility with the tie layer during mechanical recycling. We have investigated the melting temperature depression of single crystals of various polyethylenes embedded in commercial polymeric matrices with various functionalities (ester, acrylate, acetate and methacrylic acid sodium ionomer), which can be potentially used as tie layers. We demonstrate how the concentration and molecular architecture of the matrices affect the melting temperature of the embedded single crystals differently depending on the latter's molecular architecture. The main finding indicates that the tie layers are more compatible with linear polyethylene than with branched polyethylenes. Indeed, our results show that the heterogeneous Ziegler-Natta linear low-density polyethylene is incompatible with all of the tie layers tested. The depression of melting temperatures observed are in excellent agreement with the results obtained by investigating the rheological behaviour and morphological features of solution-mixed blends in which segmental interactions between polymeric chains have been, in theory, maximized. Because Ziegler-Natta linear density polyethylene is one of the most commonly used polymers as a structural layer in multi-layer applications, the findings of this study are useful as they clearly show the unsuitability of this type of polyethylene for recycling from an eco-design standpoint. The specific molecular requirements for polyethylene layers (branching content less than 0.5/100 carbon atoms) can be specified for use in packaging, guiding the eco-design and valorisation of recycled multi-layered films containing this material.

First trimester fetal head and trunk volume predict growth disturbance in twin pregnancy.

OBJECTIVE: To evaluate the usefulness of first trimester fetal head and trunk volume (FHTV) in predicting growth disturbance in twin pregnancy. METHODS: We studied 46 twin pairs from 11 and 14 weeks to delivery. There were 35 dichorionic (76%) and 11 monochorionic (24%) pregnancies. FHTV was assessed by VOCALTM. An inter-twin discrepancy in FHTV, crown-rump length (CRL) and birthweight (BW) were defined by an inter-twin difference greater than 15%. Growth retardation was defined as BW of at least one twin below the 10th percentile. RESULTS: There were 17 cases (37%) of FHTV discrepancy. BW discrepancy and growth retardation were more significantly frequent in cases with FHTV discrepancy than without [11/17 (64.7%) vs 4/29 (13.8%), P = 0.0004 and 7/17 (41.2%) vs 3/29 (10.3%), P = 0.02, respectively]. The detection of BW discordance and growth retardation were significantly higher when using FHTV discordance than CRL discrepancy in the first trimester [11/15 (73%) vs 2/15 (13.3%), P = 0.00001 and 7/10 (70%) vs 1/10 (10%), P = 0.0001, respectively]. CONCLUSION: FHTV discrepancy is a predictor for growth disturbance in twins.

Gender differences in the antioxidant response of oral administration of hydroxytyrosol and oleuropein against N-ethyl-N-nitrosourea (ENU)-induced glioma.

Brain tumorigenesis has been associated not only with oxidative stress, but also with a reduced response of non-enzyme and enzyme antioxidant defense systems. In fact, the imbalance between free-radical production and the efficiency of the antioxidant defense systems triggers the process because the central nervous system (CNS) is very sensitive to free-radical damage. Phenolic compounds, mainly oleuropein and its major metabolite hydroxytyrosol, derived from olives and virgin olive oil, have been shown to exert important anticancer activities both in vitro and in vivo due to their antioxidant properties. The present study analyzes the effects of the oral administration of oleuropein, hydroxytyrosol and the mixture of both phenolic compounds in rats with transplacental N-ethyl-N-nitrosourea (ENU)-induced brain tumors to analyze their potential effect against brain tumorigenesis through the modification of redox system components. Oxidative stress parameters, non-enzyme and enzyme antioxidant defense systems and blood chemistry were assayed in the different experimental groups. The treatment with oleuropein, hydroxytyrosol and/or the mixture of both phenolic compounds promotes a limited beneficial effect as anticancer compounds in our ENU-induced animal model of brain tumor. These effects occur via redox control mechanisms involving endogenous enzymatic and non-enzymatic antioxidant defense systems, and are highly dependent on the gender of the animals.

Sex differences exist in brain renin-angiotensin system-regulating aminopeptidase activities in transplacental ethyl-nitrosourea-induced gliomas.

INTRODUCTION: The renin angiotensin system (RAS) is emerging as an important target for the treatment of glioma. We had described that the local RAS is involved in vivo in tumor growth in the rat model of experimental C6 glioma implanted at the subcutaneous region, through the modification of several proteolytic regulatory enzymes of aminopeptidase type. METHODS: We analyze RAS-regulating aminopeptidase activities in plasma and brain tissue of control male and female rats and rats with transplacental ethylnitrosourea-induced gliomas. RESULTS: No differences were found either the mean total number of tumors per animal or the tumor volume between male and female animals. However, we have found increased levels in aspartyl aminopeptidase in both males and females and of aminopeptidase B only in males. On the contrary, decreased levels were found in aminopeptidase N and insulin-regulated aminopeptidase activities in both males and females, whereas aminopeptidase A only decreased in females. Decreased levels of aminopeptidase N, aminopeptidase B and insulin-regulated aminopeptidase were also shown in plasma of only female rats. CONCLUSIONS: Under the complexity of RAS cascade, the changes found suggest the predominant actions of angiotensin III against a decreased action of angiotensin II and angiotensin IV. We conclude that angiotensin peptides are involved in tumor growth in this rat model of glioma and that their role in tumor growth can be analyzed through their corresponding proteolytic regulatory enzymes, which make them new and attractive therapeutic targets beyond the use or angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs).

Single-port retroperitoneoscopic adrenalectomy: Initial experience and standardization of the technique.

INTRODUCTION AND OBJECTIVE: The minimally invasive surgical approach to adrenal gland pathology is the most widely used nowadays, and retroperitoneoscopy occupies a relevant place. However, the evolution of these techniques towards even less invasive surgery through single-port access is anecdotal. The aim of this work is to describe our initial experience in single-port retroperitoneoscopic surgery (SPORS) of the adrenal gland focusing on perioperative data and postoperative pain. MATERIAL AND METHODS: We collected and analyzed the demographic and operative data of a series of patients undergoing adrenalectomy through SPORS. All procedures were performed through a single 3-4 cm subcostal incision with a multichannel port. Surgical data such as operative time, bleeding, length of stay and presence of complications were collected. We used the visual analog scale (VAS) for postoperative pain assessment. RESULTS: From December 2018 to August 2020, 6 patients with different types of adrenal pathology underwent consecutive surgeries in our Department by the same surgeon using SPORS. All surgeries were performed without requiring accessory trocar placement or reconversion to open surgery. The mean operative time was 91.6 ±â€¯16.3 min, with <150 mL bleeding, mean length of stay of 35.8 ±â€¯13.3 h and postoperative pain of VAS ≤3 (median 0.5). The mean size of specimens was 57.8 ±â€¯18 mm. No complications were reported according to the Clavien-Dindo scale. CONCLUSIONS: Even in initially adverse cases, SPORS adrenalectomy is a feasible and safe technique with good cosmetic and perioperative results.

Single-port retroperitoneoscopic adrenalectomy: Initial experience and standardization of the technique. / Suprarrenalectomía retroperitoneoscópica por puerto único: experiencia inicial y estandarización de la técnica.

INTRODUCTION AND OBJECTIVE: The minimally invasive surgical approach to adrenal gland pathology is the most widely used nowadays, and retroperitoneoscopy occupies a relevant place. However, the evolution of these techniques towards even less invasive surgery through single-port access is anecdotal. The aim of this work is to describe our initial experience in single-port retroperitoneoscopic surgery (SPORS) of the adrenal gland focusing on perioperative data and postoperative pain. MATERIAL AND METHODS: We collected and analyzed the demographic and operative data of a series of patients undergoing adrenalectomy through SPORS. All procedures were performed through a single 3-4cm subcostal incision with a multichannel port. Surgical data such as operative time, bleeding, length of stay and presence of complications were collected. We used the visual analog scale (VAS) for postoperative pain assessment. RESULTS: From December 2018 to August 2020, 6 patients with different types of adrenal pathology underwent consecutive surgeries in our Department by the same surgeon using SPORS. All surgeries were performed without requiring accessory trocar placement or reconversion to open surgery. The mean operative time was 91.6±16.3minutes, with <150mL bleeding, mean length of stay of 35.8±13.3hours and postoperative pain of VAS ≤3 (median 0.5). The mean size of specimens was 57.8±18mm. No complications were reported according to the Clavien-Dindo scale. CONCLUSIONS: Even in initially adverse cases, SPORS adrenalectomy is a feasible and safe technique with good cosmetic and perioperative results.

Comparison of antiviral activity of regimens containing nucleos(t)ide (NUC) Pairs in HIV-Infected Patients Initiating REScue therapy (The NUCREST Study).

BACKGROUND: recycling nucleos(t)ides (NUCs) is useful in regions where new antiretrovirals are not available. This study compares the effectiveness of NUC-containing regimens as rescue therapy in routine care. METHODS: retrospective, multicentre cohort study (January 2001 to June 2006) of patients with ≥ 1 virological failure who started therapy with 2 NUCs and 1 non-nucleoside reverse transcriptase inhibitor (NNRTI) or a protease inhibitor (PI). The primary endpoint was the rate of treatment response at 6 months (intention-to-treat [ITT] analysis). RESULTS: we included 719 patients (average of 4 prior regimens over a median 6.1 years). The most frequent NUC pairs were tenofovir plus lamivudine (TDF+3TC; 25%), tenofovir plus stavudine (TDF+d4T; 23%), and stavudine plus didanosine (d4T+ddI; 15%). A boosted PI was used in 68% of total cases. Resistance to both NUCs was more frequent in zidovudine plus lamivudine (AZT+3TC; 22.0%), abacavir plus lamivudine (ABC+3TC; 35.5%), and stavudine plus lamivudine (d4T+3TC; 31.2%). No significant differences were observed in treatment response (overall 65%, P = .67); ddI+3TC (71%) and d4T+3TC (53%) had the highest and lowest response rates, respectively. Median time to failure was shorter with d4T+3TC, d4T+ddI, and ABC+3TC (48, 51, and 58 weeks, respectively; P = .0012). Lower response rates associated with an increasing number of thymidine analog mutations (TAMs) were observed for ABC+3TC (P = .027). CONCLUSION: the clinical utility of NUCs for rescue therapy is limited and selection should be individualized. Specific combinations (d4T+3TC and d4T+ddI) might be less efficacious.

Ultrasound predictors of birth weight in euploid fetuses with isolated single umbilical artery.

OBJECTIVE: To evaluate ultrasound parameters, including Doppler assessment, that may influence fetal growth and birth weight in cases of isolated single umbilical artery (SUA). METHODS: Sixty pregnant women with isolated SUA were studied. Doppler measurements of umbilical artery (UA), mean uterine artery (UtA) and fetal middle cerebral artery (MCA) pulsatility indices (PI) were recorded and the corresponding Z-scores were calculated according to gestational age at time of measurement. Additionally, the umbilical vein (UV) to UA diameter and perimeter ratios were calculated. The relationships between ultrasound parameters and customized birth-weight centiles according to sex and gestational age were analyzed. RESULTS: There were significant correlations between birth-weight centile and the Z-score of mean UtA-PI (r = - 0.417, P = 0.008) and the UV to UA perimeter ratio (r = 0.567, P = 0.001). A significant positive correlation between Z-scores of UA-PI and mean UtA-PI (r = 0.428, P = 0.007) was also found. When using stepwise linear regression analysis both mean UtA-PI Z-scores and UV to UA perimeter ratio were included in the predictive model of birth-weight centile (R(2) = 0.46, P < 0.001). CONCLUSIONS: Doppler assessment of mean UtA-PI and the UV to UA perimeter ratio may be useful in the clinical management of isolated SUA cases by identifying a subgroup at higher risk for fetal growth restriction.

Brain metastases treated with radiosurgery or hypofractionated stereotactic radiotherapy: outcomes and predictors of survival.

INTRODUCTION: To assess treatment outcome and prognostic factors associated with prolonged survival in patients with brain metastases (BM) treated with stereotactic radiosurgery (SRS) or hypofractionated stereotactic radiotherapy (HFSRT). METHODS/PATIENTS: This study retrospectively reviewed 200 patients with 324 BM treated with one fraction (15-21 Gy) or 5-10 fractions (25-40 Gy) between January 2010 and August 2016. 26.5% of patients received whole brain radiotherapy (WBRT) and 25% initial surgery. Demographics, prognostic scales, systemic and local controls, patterns of relapse and rescue, toxicity, and cause of death were analyzed. A stratified analysis by primary tumor was done. RESULTS: Median overall survival (OS) was 8 months from SRS/HFSRT. Breast cancer patients had a median OS of 17 months, followed by renal (11 months), lung (8 months), colorectal (5 months), and melanoma (4 months). The univariate analysis showed improved OS in females (p 0.004), RPA I-II (p < 0.001) initial surgery (p < 0.001), absence of extracranial disease (p 0.023), and good disease control (p 0.002). There were no differences in OS or local control between SRS and HFSRT or in patients receiving WBRT. Among 44% of brain recurrences, 11% were in field. 174 patients died, 10% from confirmed intracranial progression. CONCLUSIONS: SRS and HSFRT are equally effective and safe for the treatment of BM, with no exceptions among different primary tumors. Disease control, surgery, age, and prognostic scales correlated with OS. However, the lack of survival benefit regarding WBRT might become logical evidence for its omission in a subset of patients.

Granulomatous infectious disease in an immunosuppressed patient: a case report with radiological and pathological correlation.

We report here on a case of disseminated aspergillosis in an immunocompromised patient with Wegener's granulomatosis to illustrate the complexity of brain imaging diagnosis in the presence of concomitant infectious, immunological and ischemic diseases.

External photon radiation treatment for prostate cancer: Uncomplicated and cancer-free control probability assessment of 36 plans.

PURPOSE: To perform a systematic and thorough assessment, using the Uncomplicated and Cancer-Free Control Probability (UCFCP) function, of a broad range of photon prostate cancer RT treatments, on the same scenario (a unique pelvic CT set). UCFCP considers, together with the probabilities of local tumour control (TCP) and deterministic (late) sequelae (NTCP), the second primary cancer risk (SPCR) due to photon and neutron peripheral doses. METHODS AND MATERIALS: Thirty-six radiotherapy plans were produced for the same CT. 6, 10, 15 and 18 MV 3DCRT, IMRT and VMAT (77.4 Gy in 43 fractions) and 6 and 10 MV SBRT (36.25 Gy in 5 fractions with flattened and FFF beams) for Elekta, Siemens and Varian Linacs plans were included. DVH and peripheral organ dosimetry were used to compute TCP, NTCP, and SPCR (the competition and LNT models) for further plan ranking. RESULTS: Biological models (and parameters) used predicted an outcome which is in agreement with epidemiological findings. SBRT plans showed the lowest SPCR and a below average NTCPrectal. High energy plans did not rank worse than the low energy ones. Intensity modulated plans were ranked above the 3D conformal techniques. CONCLUSIONS: According to UCFCP, the best plans were the10 MV SBRTs. SPCR rates were low and did not show a substantial impact on plan ranking. High energy intensity-modulated plans did not increase in excess the average of SPCR. Even more, they ranked among the best, provided that MU were efficiently managed.

Long-term experience of bosentan for treating ulcers and healed ulcers in systemic sclerosis patients.

OBJECTIVES: Our objective was to evaluate the efficacy and tolerability of bosentan in patients with systemic sclerosis (SSc) who develop ulcers and healed ulcers. We also wanted to analyse the effect of bosentan on other skin and general outcome measurements. METHODS: In the present prospective, observational, non-controlled study, we followed all patients with SSc who started treatment with bosentan for ischaemic ulcers and healed ulcers from January 2003 to June 2006 in our centre. We recorded skin and general outcome measurements at baseline and at 6 months. RESULTS: Fifteen patients were included. After a median follow-up of 24.7 months (range: 4-36), there was a significant decrease in the number of ulcers. A trend towards efficacy was seen in the number of healed ulcers and in the severity of ulcers. No significant effect was seen in other skin and general outcome measurements. Toxicity related to bosentan included mild transitory events and one toxic hepatitis. CONCLUSION: Bosentan may be a safe long-term alternative for treating the recurrence of skin ulcers and healed ulcers in SSc patients.

In vivo administration of doxazosin in rats highly decreases serum circulating levels of testosterone through a mechanism involving the testicular renin-angiotensin system.

Men are at greater risk of cardiovascular and renal diseases than women. Several hypertensive rat models also exhibit gender differences in blood pressure. Although the mechanisms responsible for these gender differences are not clear, androgens have been shown to promote hypertension. Testosterone is produced by Leydig cells under the regulation of catecholamines acting through both alpha- and beta-adrenoceptors. Some investigators have postulated a putative role of angiotensin II (Ang II) in modulating the action of gonadotropin in Leydig cells, inhibiting testosterone production. In the present work, we analysed the potential mechanism by which the testicular renin-angiotensin system (RAS) decreases the serum circulating levels of testosterone after the in vivo administration of the long-acting selective alpha(1)-adrenergic receptor antagonist doxazosin. RAS was analysed through assessment of the activity of its proteolytic regulatory enzymes. We can conclude that the testicular testosterone production, at least in rat, is regulated by catecholamines through a mechanism involving alpha(1)-adrenergic receptors and RAS, with a putative role for Ang III. Because doxazosin is usually used as a pharmacological therapy in the treatment of hypertension and benign prostatic hyperplasia, our results could also indicate that its benefits are due, at least in part, to decreased serum circulating levels of testosterone.

Analysis of caspase activities in rat mammary tumours induced by N-methyl-nitrosourea.

Normal breast development is controlled by a balance between cell proliferation and apoptosis. The balance between the two parameters is crucial for determining the growth or regression of breast tumours in response to therapies and treatments. Therefore, it is necessary to understand the role of apoptosis in tumour progression. Active caspases participate as essential elements in the execution of apoptotic mechanisms. In the present study, we analysed the activities of caspase-3, -8 and -9 as well as cytochrome c release in N-methyl-nitrosourea (NMU)-induced rat mammary tumours, in order to establish the apoptotic events that occur in tumour growth in this animal model. Forty female virgin Wistar rats were randomly divided into two groups. One group was injected intraperitoneally with three doses of 50 mg/kg body weight of NMU. The control group received the vehicle only. After 122 days of NMU injection, the rats were sacrificed and the tumours were excised and processed. Results showed that in mammary tumours induced by NMU, the apoptotic death receptor-mediated pathway is activated through caspase-3 and -8, but the apoptotic mitochondrial pathway is suppressed through a non-activating process of caspase-9 activity, despite the release of cytochrome c. In conclusion, these findings have demonstrated a suppression of the apoptotic mitochondrial pathway through a non-activating process of caspase-9 activity, despite the release of cytochrome c in mammary tumours induced by NMU. Although the apoptotic death receptor-mediated pathway is activated, it is not enough to maintain the balance between proliferation and apoptosis, and thus determine the overall growth of the tumour.

CHARACTERIZATION OF THE EPITHERMAL NEUTRON FIELD PRODUCED BY p+7Li REACTION IN A TANDEM ACCELERATOR USING A BONNER SPHERE SPECTROMETER.

The proton beam produced in the Nuclear Physics line of the tandem accelerator of the Centro Nacional de Aceleradores was used to generate a neutron field. In particular, 1.912 MeV protons were used to produce well-known epithermal neutrons through the p+7Li → n+7Be reaction. The aim of the work was to characterize this field while testing the performance of a Bonner sphere spectrometer in the epithermal range. Measurements were performed in four locations at different angle (0°, 30°, 60° and 90°) from beam incidence direction in order to study the angular dependence of the field. Both a parametric and numerical unfolding methods were tested to process the counts of the central detectors and obtain the energy distribution of the neutron fluence. In addition, a Monte Carlo simulation was carried out to complete the study and provide a guess spectrum for numerical unfolding. It was found that the fluence rate and mean energy decrease as the angle from beam direction increases. Total fluence was 2.75, 1.36, 0.366 and 0.216 cm-2 per charge collected in the target at 0°, 30°, 60° and 90°, respectively. Mean energy of the field ranges from 46 to 17 keV at 0° and 60°, respectively. In all cases, given that the irradiation room is so large, the contribution of thermal neutrons to the field is small. Regarding the unfolding, the total fluences estimated by all methods were in agreement within the uncertainties.

Dose distribution of secondary radiation in a water phantom for a proton pencil beam-EURADOS WG9 intercomparison exercise.

Systematic 3D mapping of out-of-field doses induced by a therapeutic proton pencil scanning beam in a 300 × 300 × 600 mm3 water phantom was performed using a set of thermoluminescence detectors (TLDs): MTS-7 (7LiF:Mg,Ti), MTS-6 (6LiF:Mg,Ti), MTS-N (natLiF:Mg,Ti) and TLD-700 (7LiF:Mg,Ti), radiophotoluminescent (RPL) detectors GD-352M and GD-302M, and polyallyldiglycol carbonate (PADC)-based (C12H18O7) track-etched detectors. Neutron and gamma-ray doses, as well as linear energy transfer distributions, were experimentally determined at 200 points within the phantom. In parallel, the Geant4 Monte Carlo code was applied to calculate neutron and gamma radiation spectra at the position of each detector. For the cubic proton target volume of 100 × 100 × 100 mm3 (spread out Bragg peak with a modulation of 100 mm) the scattered photon doses along the main axis of the phantom perpendicular to the primary beam were approximately 0.5 mGy Gy-1 at a distance of 100 mm and 0.02 mGy Gy-1 at 300 mm from the center of the target. For the neutrons, the corresponding values of dose equivalent were found to be ~0.7 and ~0.06 mSv Gy-1, respectively. The measured neutron doses were comparable with the out-of-field neutron doses from a similar experiment with 20 MV x-rays, whereas photon doses for the scanning proton beam were up to three orders of magnitude lower.

COMPARISON OF RESPONSE OF PASSIVE DOSIMETRY SYSTEMS IN SCANNING PROTON RADIOTHERAPY-A STUDY USING PAEDIATRIC ANTHROPOMORPHIC PHANTOMS.

Proton beam therapy has advantages in comparison to conventional photon radiotherapy due to the physical properties of proton beams (e.g. sharp distal fall off, adjustable range and modulation). In proton therapy, there is the possibility of sparing healthy tissue close to the target volume. This is especially important when tumours are located next to critical organs and while treating cancer in paediatric patients. On the other hand, the interactions of protons with matter result in the production of secondary radiation, mostly neutrons and gamma radiation, which deposit their energy at a distance from the target. The aim of this study was to compare the response of different passive dosimetry systems in mixed radiation field induced by proton pencil beam inside anthropomorphic phantoms representing 5 and 10 years old children. Doses were measured in different organs with thermoluminescent (MTS-7, MTS-6 and MCP-N), radiophotoluminescent (GD-352 M and GD-302M), bubble and poly-allyl-diglycol carbonate (PADC) track detectors. Results show that RPL detectors are the less sensitive for neutrons than LiF TLDs and can be applied for in-phantom dosimetry of gamma component. Neutron doses determined using track detectors, bubble detectors and pairs of MTS-7/MTS-6 are consistent within the uncertainty range. This is the first study dealing with measurements on child anthropomorphic phantoms irradiated by a pencil scanning beam technique.

Experimental evaluation of neutron dose in radiotherapy patients: Which dose?

PURPOSE: The evaluation of peripheral dose has become a relevant issue recently, in particular, the contribution of secondary neutrons. However, after the revision of the Recommendations of the International Commission on Radiological Protection, there has been a lack of experimental procedure for its evaluation. Specifically, the problem comes from the replacement of organ dose equivalent by the organ-equivalent dose, being the latter "immeasurable" by definition. Therefore, dose equivalent has to be still used although it needs the calculation of the radiation quality factor Q, which depends on the unrestricted linear energy transfer, for the specific neutron irradiation conditions. On the other hand, equivalent dose is computed through the radiation weighting factor wR, which can be easily calculated using the continuous function provided by the recommendations. The aim of the paper is to compare the dose equivalent evaluated following the definition, that is, using Q, with the values obtained by replacing the quality factor with wR. METHODS: Dose equivalents were estimated in selected points inside a phantom. Two types of medical environments were chosen for the irradiations: a photon- and a proton-therapy facility. For the estimation of dose equivalent, a poly-allyl-diglicol-carbonate-based neutron dosimeter was used for neutron fluence measurements and, additionally, Monte Carlo simulations were performed to obtain the energy spectrum of the fluence in each point. RESULTS: The main contribution to dose equivalent comes from neutrons with energy higher than 0.1 MeV, even when they represent the smallest contribution in fluence. For this range of energy, the radiation quality factor and the radiation weighting factor are approximately equal. Then, dose equivalents evaluated using both factors are compatible, with differences below 12%. CONCLUSIONS: Quality factor can be replaced by the radiation weighting factor in the evaluation of dose equivalent in radiotherapy environments simplifying the practical procedure.