Differences in mental health problems in LGBT+ first year college students in Chile during the pandemic.

PURPOSE: To examine the differences in mental health problems by sexual orientation and gender identity in first-year university students in Chile during the pandemic. METHODS: 7,213 first-year students aged 18 years and older from five universities participated as part of the World Mental Health - International College Student initiative in Chile. Students completed an online self-report survey between 2020 and 2021 that included measures of lifetime and 12-month major depressive episode, generalized anxiety disorder, panic disorder, bipolar disorder, drug abuse/dependence, alcohol dependence, non-suicidal self-injuries, and suicidal risk. Prevalence of mental health problems were estimated and the differences by sexual orientation and gender identity were examined using logistic and multinomial logistic regression models. RESULTS: Between 84.1% and 98% of lesbian, gay, bisexual, trans, and other sexual and gender minority (LGBT+) students screened positive for at least one lifetime mental health problem and between 67.6% and 90.6% for two or more problems. For most outcomes, non-heterosexual (Odds Ratio [OR] between 1.25 and 7.00) and trans and gender nonconforming students (OR between 1.72 and 5.81) had significantly higher odds of positive screening for lifetime mental health problems than heterosexual and cisgender students, respectively. Similar results were observed for 12-month mental health problems. CONCLUSION: The results show differences in the prevalence of mental health problems in LGBT+ university students in Chile, which are consistent with those found in other countries. These results may be useful for planning interventions to improve the mental health of LGBT+ students.

Technical note: Angular dependence in fiber optic dosimetry using YVO4 :Eu3.

BACKGROUND: Fiber optic dosimetry (FOD) has emerged as a useful technique that can be used in those cases when intracavitary, real time, high spatial resolution dose assessment is required. Among the several factors characterizing a dosimeter, angular response of FOD probes has to be assessed in order to consider possible clinical application. PURPOSE: The objective of this study was to characterize the angular response of a FOD probe based on a cylindrical shaped YVO4 :Eu3+ scintillator under irradiation with a 6 MV photon beam generated by a linear accelerator (LINAC). METHODS: A FOD probe was irradiated inside a plastic phantom using a 6 MV LINAC photon beam at different azimuthal angles (0° to 360°, 15° steps). Scintillation output was measured with a photomultiplier tube. Similar measurements were performed with a second FOD probe having an optical filter interposed between the scintillator and the fiber. Monte Carlo simulations using PENELOPE were carried out in order to interpret the observed results. RESULTS: The FOD output was symmetrical with respect to the scintillator axis. For the unfiltered probe, the signal was maximum at rear incidence (0°) and steadily decreased down to its minimum value at frontal incidence (180°) having a signal ratio of 37%. The output of the filtered probe showed a plateau from 15° up to 115°. The signal was maximum at 60° and minimum at 180° having a signal ratio of 16%. Monte Carlo simulations predicted symmetry of the deposited dose about 0° and 90°, which contrasts with experimental findings. CONCLUSIONS: Photoluminescence (PL) of the scintillator induced by the Cherenkov light increases the angular dependence. Radiation attenuation inside the scintillator and partial light collection of the scintillation yield by the optical fiber (OF) are responsible for asymmetrical response. Results from this study should be considered in order to minimize angular dependence in FOD.

Scintillation properties of the YVO4:Eu3+ compound in powder form: its application to dosimetry in radiation fields produced by pulsed mega-voltage photon beams.

The investigation of scintillation properties of europium doped yttrium orthovanadate shows the suitability of this material for fiber-based dose rate measurements. All measurements were carried out with a 6 MV Varian linear accelerator. The temperature dependence of the signal is lower than that of the plastic scintillators reported so far. By measuring the afterglow of probes between Linac-pulses, the signal due to the stem effect can be successfully eliminated. Comparison of depth dose profiles in a water phantom for radiation field dimensions between 1 x 1 cm(2) and 10 x 10 cm(2) shows that the probes are suitable for small fields having dimensions up to 1 x 1 cm(2). The high light yield of probes having dimensions of 1 mm opens up the possibility for their use in spatially confined radiation fields, such as in intensity-modulated radiotherapy (IMRT) and volume-modulated radiation therapy (VMAT).