Improved FBX chemical dosimeter system with enhanced radiochemical yield for reference dosimetry in radiobiology and radiotherapy research

Radiation dosimetry plays important role in the reproducibility of radiobiology experiments, in the replicability of results, as well as in the successful and safe use of radiotherapy procedures. The consistency and accuracy of the applied dosimetry methods pre-define the outcomes of these applications. This paper presents a version of the well-known ferrous sulphate – benzoic acid – xylenol orange (FBX) chemical dosimeter with improved sensitivity, accuracy and precision. Sensitivity is increased due to a slight modification in composition and the preparation procedures. We use stock solutions for the preparation of the dosimeter solution, which consists of 1 mM ferrous sulphate and 16 mM benzoic acid with 0.25 mM xylenol orange added post-irradiation. The nonlinear response to the absorbed dose of this system is eliminated by the increased ferrous sulphate concentration, permitting the calculation of the absorbed dose by a linear relationship between the absorbed dose and the optical absorbance of the solution. The measured chemical yield of our dosimeter is 9.08⋅10−6mol/J for 6 MV photon beams and 6.42⋅10−6mol/J for 250 kVp x-rays. This is a 24% enhancement over the original FBX solution, which permits a finer dose resolution. The accuracy and precision of our method is assured by a well-designed and consistently used practice. A custom designed multipurpose PMMA slab phantom was used for irradiation in reference conditions. This phantom can be used for irradiation in reference conditions of dosimetric solutions, dosimetric films and chemical or biological samples. The combined standard uncertainty of this system is 1.12%, which can be improved by using an appropriate temperature correction factor. Furthermore, a working protocol has been established which allows dosimetry measurements using less than 1 mL dosimetric solutions

Alteration of body composition in rats: Effect of organic chromium and L-carnitine

A growth trial was carried out to test the effect of organic, trivalent chromium and L-carnitine on the body composition of growing rats. At the same time, an evaluation of different measurement methods (weight of epididymal fat pad, adipocyte morphometry, total body electrical conductivity) was performed. Outbred Wistar rats of 30 days of age were fed diets of different (0, 10 and 20%) protein level. The diets were supplemented with 4 mg/kg Cr as chromium nicotinate, and 100 mg/kg L-carnitine. The experimental feeding lasted 15 days, after a 5-day-long adjustment period. It was found that Cr addition increased feed intake. Both treatments caused changes in body composition, increasing fat and protein deposition. Organic chromium had no effect at either protein level, while L-carnitine improved the protein retention only at an optimum (20%) protein supply. No statistically significant correlation was found between total body electrical conductivity (TOBEC) and body composition, which could be attributed to the great individual differences. A close correlation was found among total body fat percentage, weight of epididymal fat pad and the adipocyte surface. The data suggest that there is an interaction between dietary protein supply and the effect of repartitioning agents

Influence of feeding intensity on corporeal development, body composition and sexual maturity in female rabbits

Twenty-six 6-week old female New Zealand White rabbits were divided into two groups: ad libitum (AL) and 70% restricted (RS) feeding. At the beginning of the experiment the liveweights were practically the same: 0.99 ± 0.08 vs. 1.01 ± 0.08 kg in group AL and RS, respectively. At 18 weeks of age the body weight of Group RS rabbits was 84.7% (3.14 ± 0.24 kg) of the group AL (3.71 ± 0.31 kg). The apparent digestibility of crude protein was significantly (p < 0.001) higher in Group RS than in Group AL (76.5 ± 1.4 vs. 73.0 ± 2.7%). The daily water consumption was significantly (p < 0.05) higher (3.5 ml/g DM intake) in Group RS as compared to Group AL (1.9 ml/g DM). Since the average body weight in Group RS at 18 weeks was the same as that of Group AL at 14 weeks of age (3.14 kg), the comparison of the live body measures and indices was based on these ages. Animals fed ad libitum or restricted show no differences at the defined age in most live body measurements except in heart girth and rump width, which were significantly (p < 0.05) shorter in Group AL than in Group RS (29.3 ± 0.8, 5.7 ± 0.5 and 30.7 ± 1.0, 6.2 ± 0.3 cm, respectively). Body capacity was significantly (p < 0.05) smaller in Group AL, as the head capacity-body capacity proportion was significantly (p < 0.05) higher in Group AL than in Group RS (1653.1 ± 134.5, 22.0 ± 2.5 and 1913.7 ± 168.7, 17.7 ± 1.9, respectively). Due to restricted feeding the growth of the head proved to be less intensive than that of the body at the same body weight. The body in these does tended to be wider. Since the head in comparison to length or capacity of the body was smaller in does fed 70% of ad libitum, it could be concluded that the development of body parts of restricted-fed does was unequal (allometric growth). The effect of feed restriction reflected in lower dry matter and fat, and a higher ash and protein content both in total body and in dry matter composition of rabbits at 18 weeks of age. Restricted feeding delayed sexual maturity (69 vs. 92% of rabbits) with later starting ovarian activity, weaker ovarian responsiveness, and a smaller number of tertiary follicles on the ovarian surface

Estimation of agro-ecosystem services using biogeochemical models

Agro-ecosystem services are the various benefits (e.g., crop yield) that people freely obtain from the properly functioning agricultural lands. The estimated changes in climatic conditions including increasing temperature, with particular attention to the summer means, together with the expected changes in the temporal precipitation distribution pose enormous challenge to the agriculture. Currently, dynamic system models are most frequently used tools that are capable of estimating the prospective effects of climate change on agro-ecosystems. A deterministic biogeochemical model is presented that is developed by Hungarian scientists within the framework of the AgroMo project. The main goal of the AgroMo project is to develop climate-smart strategies in order to mitigate the effect of potential future hazards in the context of climate change by 1) creating a complex, state-of-the-art experimental platform; 2) producing ten new, 0.1° spatial resolution climate scenarios based on the RCP (Representative Concentration Pathway) 4.5 and RCP8.5 scenarios; 3) developing an integrated assessment and modeling framework that is capable of simulating every major land use types; 4) analyzing/simulating a great number of adaptation strategies that can be used to support decision makers. Based on the preliminary simulation results, climate change will most likely expose significant negative impact on the spring sown crops in Hungary. Although, the yield losses could be avoided with irrigation or could be mitigated with earlier sowing, the role of winter crops is likely to become more significant in Hungary in the future

Prostate-specific membrane antigen-based imaging for stereotactic irradiation of low-volume progressive prostate cancer: a single-center experience

IntroductionProstate-specific membrane antigen (PSMA) is a transmembrane protein that may be expressed on the surface of prostate cancer (PC) cells. It enables a more sensitive and specific diagnosis PC, compared to conventional anatomical imaging.AimThe integration of PSMA-based imaging in the personalized radiotherapy of PC patients and the evaluation of its impact on target volume definition if stereotactic body radiotherapy (SBRT) is planned for locally recurrent or oligometastatic disease.Patients and methodsThe data from 363 examinations were analyzed retrospectively. Inclusion criteria were histologically verified PC and clinical data suggesting local recurrence or distant metastasis. Whole-body 99mTc-PSMA-I&amp;S single-photon emission computed tomography (SPECT)/CT or 18F-JK-PSMA-7 positron emission tomography/computer tomography (PET/CT) was carried out, and the evaluation of the scans and biological tumor volume contouring was performed at the Department of Nuclear Medicine. The target volume delineation on topometric CT (TCT) scan was performed at the Department of Oncotherapy. The comparison of the two volumes was performed by image fusion and registration.ResultsFrom 363 PSMA isotope-based examinations, 84 lesions of 64 patients were treated with SBRT. In 50 patients, 70 lesions were examined for intermodality comparison. The target volume defined by the PSMA density was significantly smaller than the tumor size defined by the TCT scan: GTVCT (gross tumor volume on the TCT), 27.58 ± 46.07 cm3; BTVPSMA (biological target volume on the PSMA-based examination), 16.14 ± 29.87 cm3. During geometrical analyses, the Dice similarity coefficient (DSC) was 0.56 ± 0.20 (0.07–0.85). Prostate-specific antigen (PSA) control was performed to evaluate the response: mean pre-radiotherapy (pre-RT) PSA was 16.98 ng/ml ( ± SD: 33.81), and post-RT PSA at 3 months after SBRT was 11.19 ng/ml ( ± SD: 32.85). Three-month post-therapy PSMA-based imaging was performed in 14 cases, in which we observed a decrease or cessation of isotope uptake. Conventional imaging control was performed in 42 cases (65.6% of all cases): 22 (52.4%) complete remissions, 14 (33.3%) partial remissions, four (9.5%) stable diseases, and two (4.8%) progressive diseases were described.ConclusionPSMA-based imaging is a promising diagnostic method for specifying the stage and detecting the low-volume progression. Our results suggest that PSMA-based hybrid imaging can influence treatment decisions and target volume delineation for SBRT