School setting and teaching experience as risk factors for depressive symptoms in teachers

A representative sample of teachers working at the primary or secondary grade level in both public and private schools answered an anonymous questionnaire on sociodemographic information and completed the Center for Epidemiologic Studies Rating Scale for Depression (CES-D). The teachers were classified as depressed when they scored ≥ 16 on the CES-D; 27.5% of the subjects were above this cut-off score. Logistic regression was used to calculate a multivariate model with the variables school ownership, grade level and teaching experience. Working in a public school, teaching at the primary level and longer teaching experience all increased the risk of depressive symptomatology.

Improving quality of care and clinical outcomes for rectal cancer through clinical audits in a multicentre cancer care organisation

Introduction

Colorectal cancer treatment requires a complex, multidisciplinary approach. Because of the potential variability, monitoring through clinical audits is advisable. This study assesses the effects of a quality improvement action plan in patients with locally advanced rectal cancer and treated with radiotherapy.

Methods

Comparative, multicentre study in two cohorts of 120 patients each, selected randomly from patients diagnosed with rectal cancer who had initiated radiotherapy with a curative intent. Based on the results from a baseline clinical audit in 2013, a quality improvement action plan was designed and implemented; a second audit in 2017 evaluated its impact.

Results

Standardised information was present on 77.5% of the magnetic resonance imaging (MRI) staging reports. Treatment strategies were similar in all three study centres. Of the patients whose treatment was interrupted, just 9.7% received a compensation dose. There was an increase in MRI re-staging from 32.5 to 61.5%, and a significant decrease in unreported circumferential resection margins following neoadjuvant therapy (ypCRM), from 34.5 to 5.6% (p <  0.001).

Conclusions

The comparison between two clinical audits showed improvements in neoadjuvant radiotherapy in rectal cancer patients. Some indicators reveal areas in need of additional efforts, for example to reduce the overall treatment time.

Pantak Therapax SXT 150: performance assessment and dose determination using IAEA TRS-398 protocol

The performance assessment and beam characteristics of the Therapax SXT 150 unit, which encompass both low and medium-energy beams, were evaluated. Dose determination was carried out by implementing the International Atomic Energy Agency (IAEA) TRS-398 protocol and measuring all the dosimetric parameters in order to have a solid, consistent and reliable data set for the unit. Mechanical movements, interlocks and applicator characteristics agreed with specifications. The timer exhibited good accuracy and linearity. The output was very stable, with good repeatability, long-term reproducibility and no dependence on tube head orientation. The measured dosimetric parameters included beam first and second half-value layers (HVLs), absorbed dose rate to water under reference conditions, central axis depth dose distributions, output factors and beam profiles. Measured first HVLs agreed with comparable published data, but the homogeneity coefficients were low in comparison with typical values found in the literature. The timer error was significant for all filters and should be taken into consideration for the absorbed dose rate determination under reference conditions as well as for the calculation of treatment times. Percentage depth-dose (PDD) measurements are strongly recommended for each filter-applicator combination. The output factor definition of the IAEA TRS-398 protocol for medium-energy X-ray qualities involves the use of data that is difficult to measure. Beam profiles had small penumbras and good symmetry and flatness except for the lowest energy beam, for which a heel effect was observed.

Comparison of dose calculation algorithms in phantoms with lung equivalent heterogeneities under conditions of lateral electronic disequilibrium

An extensive set of benchmark measurement of PDDs and beam profiles was performed in a heterogeneous layer phantom, including a lung equivalent heterogeneity, by means of several detectors and compared against the predicted dose values by different calculation algorithms in two treatment planning systems. PDDs were measured with TLDs, plane parallel and cylindrical ionization chambers and beam profiles with films. Additionally, Monte Carlo simulations by means of the PENELOPE code were performed. Four different field sizes (10 x 10, 5 x 5, 2 x 2, and 1 x 1 cm2) and two lung equivalent materials (CIRS, p(w)e=0.195 and St. Bartholomew Hospital, London, p(w)e=0.244-0.322) were studied. The performance of four correction-based algorithms and one based on convolution-superposition was analyzed. The correction-based algorithms were the Batho, the Modified Batho, and the Equivalent TAR implemented in the Cadplan (Varian) treatment planning system and the TMS Pencil Beam from the Helax-TMS (Nucletron) treatment planning system. The convolution-superposition algorithm was the Collapsed Cone implemented in the Helax-TMS. The only studied calculation methods that correlated successfully with the measured values with a 2% average inside all media were the Collapsed Cone and the Monte Carlo simulation. The biggest difference between the predicted and the delivered dose in the beam axis was found for the EqTAR algorithm inside the CIRS lung equivalent material in a 2 x 2 cm2 18 MV x-ray beam. In these conditions, average and maximum difference against the TLD measurements were 32% and 39%, respectively. In the water equivalent part of the phantom every algorithm correctly predicted the dose (within 2%) everywhere except very close to the interfaces where differences up to 24% were found for 2 x 2 cm2 18 MV photon beams. Consistent values were found between the reference detector (ionization chamber in water and TLD in lung) and Monte Carlo simulations, yielding minimal differences (0.4%+/-1.2%). The penumbra broadening effect in low density media was not predicted by any of the correction-based algorithms, and the only one that matched the experimental values and the Monte Carlo simulations within the estimated uncertainties was the Collapsed Cone Algorithm.

Comparison study of MOSFET detectors and diodes for entrancein vivodosimetry in 18 MV x-ray beams

The feasibility of dual bias dual metal oxide semiconductor field effect transistors (MOSFETs) for entrance in vivo dose measurements in high energy x-rays beams (18 MV) was investigated. A comparison with commercially available diodes for in vivo dosimetry for the same energy range was performed. As MOSFETs are sold without an integrated build-up cap, different caps were tested: 3 cm bolus, 2 cm bolus, 2 cm hemispherical cap of a water equivalent material (Plastic Water) and a metallic hemispherical cap. This metallic build-up cap is the same as the one that is mounted on the in vivo diode used in this study. Intrinsic precision and response linearity with dose were determined for MOSFETs and diodes. They were then calibrated for entrance in vivo dosimetry in an 18 MV x-ray beam. Calibration included determination of the calibration factor in standard reference conditions and of the correction factors (CF) when irradiation conditions differed from those of reference. Correction factors for field size, source surface distance, wedge, and temperature were determined. Sensitivity variation with accumulated dose and the lifetime of both types of detectors were also studied. Finally, the uncertainties of entrance in vivo measurements using MOSFET and diodes were discussed. Intrinsic precision for MOSFETs for the high sensitivity mode was 0.7% (1 s.d.) as compared to the 0.05% (1 s.d.) for the studied diodes. The linearity of the response with dose was excellent (R2 = 1.000) for both in vivo dosimetry systems. The absolute values of the studied correction factors for the MOSFETs when covered by the different build-up caps were of the same order of those determined for the diodes. However, the uncertainties of the correction factors for MOSFETs were significantly higher than for diodes. Although the intrinsic precision and the uncertainty on the CF was higher for MOSFET detectors than for the studied diodes, the total uncertainty in entrance dose determination, once they were calibrated, was of 2.9% (1 s.d.) while for diodes it was 2.0% (1 s.d.). MOSFETs showed no sensitivity variation with accumulated dose or temperature. When used in the high sensitivity mode, after approximately 50 Gy of accumulated dose MOSFETs could no longer be used as radiation dosimeters. In conclusion, MOSFETs can be used for entrance in vivo dosimetry in high energy x-rays beams if covered by an appropriate build-up cap. Metallic build-up caps, such as those used for in vivo diodes, have the advantage of greater patient comfort and less perturbation of the treatment field than the other build-up caps tested, while keeping the correction factors of the same order.