Assessment of Multi-leaf Collimator Positional Accuracy Using Radiochromic EBT3 Film and an Electronic Portal Imaging Device

This study aimed to evaluate multi-leaf collimator (MLC) positional accuracy by using an electronic portal imaging device (EPID) and radiochromic EBT3 film. Furthermore, the MLC�s positional accuracy at different gantry and collimator angles of a Siemens ONCOR linear accelerator (linac) was evaluated. A picket fence test was performed to evaluate the MLC�s positional accuracy at various gantry and collimator angles of the linac. The EPID and the EBT3 films were sequentially irradiated seven times at 2-cm intervals by making a rectangular field (0.3 � 19 cm2). The full-width at half-maximum (FWHM) of each band (field) was calculated for all leaves by using inhouse software. Then, variations between the actual and the planned leaf locations were obtained by using the EPID and the EBT3 film at various gantry and collimator angles. The mean FWHM, acquired using the EPID and the EBT3 film ranged from 2.331 - 3.647 mm and 2.059 - 4.001 mm, respectively. Variations between the actual and the planned leaf locations were found to be affected by changes in the collimator and the gantry angles. Moreover, a -0.060 - 1.588 mm difference we seen between the result obtained from the EBT3 film and that obtained from the EPID. The mean FWHM, at most angles, for the EBT3 film was larger than that for the EPID. The findings showed average deviations for the EPID (0.001 - 0.669 mm) and EBT3 film (0.007 - 1.001 mm); these values agreed within the tolerance level (±1 mm). Furthermore, good agreement was found between the results obtained from the EPID and the EBT3 film; these two dosimetric methods can be used interchangeably, but each must be chosen considering its advantages and disadvantages. © 2020, The Korean Physical Society

Evaluation of Hyperprolactinemia Risk Factors in Infertile Women Referred to Yazd Infertility CENTER: A Cross-sectional Study

Background: Hyperprolactinemia is one of the most common causes of infertility in women. The prevalence of pituitary tumors is 25-30% among infertile participants with hyperprolactinemia. Objective: The aim of this study was to describe the causes of hyperprolactinemia in infertile women referred to Yazd Infertility Center. Materials and Methods: This cross-sectional study was conducted with 182 infertile women with hyperprolactinemia who were referred to Yazd Infertility Center from February 2018 to October 2019. Serum prolactin was assessed by the human prolactin ELISA kit according to the Padtan Gostar Isar protocol. The age, duration of infertility, causes of hyperprolactinemia, and type of infertility treatment were noted. The MRI findings were added. Results: The mean age of participants was 28.9 ± 0.36 yr and the prolactin level was 76 ± 8.97 ng/ml. The etiology of hyperprolactinemia among the study participants was 35 participants (19.2%) with pituitary adenoma, 47 participants (25.8%) with polycystic ovary syndrome, 14 participants (7.7%) with pituitary adenoma and polycystic ovary syndrome, and 86 participants (47.3%) with idiopathic hyperprolactinemia. The results of this study showed that there was no statistically significant difference between the mean prolactin levels in participants with different causes of hyperprolactinemia (p = 0.31). Conclusion: Idiopathic hyperprolactinemia and polycystic ovary syndrome are the most common reasons for hyperprolactinemia. Key words: Hyperprolactinemia, Infertility, PCOS

Cerebrovascular responses in mice deficient in the potassium channel, TREK-1

We tested the hypothesis that TREK-1, a two-pore domain K channel, is involved with dilations in arteries. Because there are no selective activators or inhibitors of TREK-1, we generated a mouse line deficient in TREK-1. Endothelium-mediated dilations were not different in arteries from wild-type (WT) and TREK-1 knockout (KO) mice. This includes dilations of the middle cerebral artery to ATP, dilations of the basilar artery to ACh, and relaxations of the aorta to carbachol, a cholinergic agonist. The nitric oxide (NO) and endothelium-dependent hyperpolarizing factor components of ATP dilations were identical in the middle cerebral arteries of WT and TREK-1 KO mice. Furthermore, the NO and cyclooxygenase-dependent components were identical in the basilar arteries of the different genotypes. Dilations of the basilar artery to α-linolenic acid, an activator of TREK-1, were not affected by the absence of TREK-1. Whole cell currents recorded using patch-clamp techniques were similar in cerebrovascular smooth muscle cells (CVSMCs) from WT and TREK-1 KO mice. α-linolenic acid or arachidonic acid increased whole cell currents in CVSMCs from both WT and TREK-1 KO mice. The selective blockers of large-conductance Ca-activated K channels, penitrem A and iberiotoxin, blocked the increased currents elicited by either α-linolenic or arachidonic acid. In summary, dilations were similar in arteries from WT and TREK-1 KO mice. There was no sign of TREK-1-like currents in CVSMCs from WT mice, and there were no major differences in currents between the genotypes. We conclude that regulation of arterial diameter is not altered in mice lacking TREK-1