Shielding design aspects of SR in 3 GeV ILSF.

Iranian Light Source Facility (ILSF) is an under-construction synchrotron radiation accelerator consisting of a 150 MeV linac, a booster synchrotron operating from 150 MeV to 3 GeV, and a 3 GeV storage ring that stores a maximum of 400 mA current of electrons. As the stored beam circulates, a fraction of the beam is lost due to interactions with gas molecules, interactions among beam particles, and orbital bending, which produce radiation. The bulk shielding calculation for the ILSF and the input parameters used for this analysis are discussed in this paper. The potential of skyshine neutrons to cause radiation hazards is investigated as well. Moreover, the design and shielding simulation using the FLUKA Monte Carlo code is presented for the linac beam stop and primary and scattered gas bremsstrahlung for the first optics enclosure of the ILSF spectro microscopy beamline. Our designed radiation shielding system guarantees that the annual dose in all areas around the ILSF machine does not exceed the dose limit of 1 mSv.

Evaluating the effects of metal artifacts on dose distribution of the pelvic region.

AIM OF THE STUDY: Some cancerous patients have hip prosthesis of metal elements when they undergo radiation therapy. Metal implants are a cause of metal artifacts in computed tomography (CT) images due to their higher density compared to normal tissues. The aim of this study is to evaluate the quantitative effects of metal artifacts on dose distribution of the pelvic region. MATERIALS AND METHODS: Seven patients with metal implants in the pelvic region were scanned and CT images were exported to the Monaco treatment planning system. Based on the diagnosis of each patient, three-dimensional plans were implemented on CT images and dose distributions were extracted. At the next step, metal artifacts were contoured and electron densities of these new structures were modified to the extent of soft tissue. Finally, dose distributions and the differences were investigated by VeriSoft software. RESULTS: The results of this study showed that if the electron density to metal artifacts is not assigned properly, it will increase the calculated monitor units (MUs) by almost 3.78 MUs/fraction which will significantly affect total dose distribution of treatment. CONCLUSION: For the precise implementation of the treatment and in order to minimize the systematic errors related to the calculated MUs, necessary corrections on the electron density of metal artifacts should be considered before the treatment planning. The issue will be more critical in advanced treatment modalities where dose escalation is needed.

Traffic Noise Exposure Increases Gastric Pepsin Secretion in Rat.

Noise is considered as one of the most severe sources of environmental and workplace constraints. Many noise effects are well known on immune function, hormonal levels, cardiovascular and respiratory systems. In this study, our aim is to evaluate the effects of traffic noise exposure on basal and stimulated gastric pepsin secretion. 48 male rats were exposed to traffic noise (86 dB) for a short term of (8h/day for 1 day) and a long term of (8h/day for 7, 14, 21 and 28 days) as well as a control group. The gastric contents were collected by the wash-out technique. Pepsin secretion was measured by employing the Anson method. Histological studies were carried out on the epithelial layer. The corticosteroid hormone was measured in the serum for the stress augmentation. The present finding indicated no changes in pepsin secretion content in the short term, but in the 14 and 21 days traffic noise exposure, basal gastric pepsin secretion increased markedly compared to the control group. Histological results showed that the number of oxyntic glands and cell nuclei decreased in comparison with the control group while the thickness of the epithelial layer increases. In addition, the corticosterone levels increase in all groups in comparison with the control. It seems that the increase of gastric pepsin secretion is due to the description and translation processes in the peptic cells and needs enough time for completion.

Short Form-McGill Pain Questionnaire-2 (SF-MPQ-2): A Cross-Cultural Adaptation and Validation Study of the Persian Version in Patients with Knee Osteoarthritis.

BACKGROUND: We aimed to develop and validate the Persian version of Short Form McGill Pain Questionnaire-2 (SF-MPQ-2) in patients with knee osteoarthritis. METHODS: Translation and back translation was performed using Beaton's guideline. After a consensus has achieved on the Persian version of SF-MPQ-2, it was administered to 30 patients with knee osteoarthritis in a pilot study. Then, we enrolled 100 patients with knee osteoarthritis to fill the final SF-MPQ-2 as well as SF-36 and WOMAC questionnaires. Forty-three patients returned 3 days after the initial visit to fill the Persian SF-MPQ-2 for the second time. Construct validity was tested by Pearson's correlation coefficient between subscales of SF-MPQ-2 and subscales of SF-36 and WOMAC. Internal consistency for total and subscales was calculated by Cronbach's alpha and reliability between test retest was performed using Intraclass correlation coefficient (ICC). RESULTS: ICC for subscales of SF-MPQ-2 ranged from 0.73 to 0.90. The ICC for total SF-MPQ-2 was 0.90. Cronbach's alpha for subscales was 0.65-0.74 at the first visit and 0.58-0.81 at the second visit. Cronbach's alpha for the total questionnaire was 0.88 and 0.91 at the first and second visit, respectively. Pearson's correlation coefficient was highly significant when comparing subscales specifically with WOMAC (r=-0.47 to -0.61; P<0.001). Interscale correlation between subscales of SF-MPQ-2 was significant as well (r: 0.43-0.88, P<0.001). CONCLUSIONS: Persian SF-MPQ-2 showed excellent reliability and good to excellent internal consistency throughout the questionnaire. It is a valid and reliable instrument for measuring the pain intensity and applicable in osteoarthritic pain assessment.

Traffic noise exposure increases gastric acid secretion in rat.

Noise is considered as one of the most severe sources of environmental and work place constraints. Noise effects on immune function, hormonal levels, cardiovascular and respiratory systems are well known. The aim of the study is to evaluate the effects of traffic noise on basal and stimulated gastric acid secretion. 48 healthy rats were divided into five traffic noise exposures (1, 7, 14, 21, 28 days) and a control groups. Pentagastrin was used i.p. for stimulation of gastric acid secretion. The gastric contents were collected by the wash-out technique and then titrated. Histological studies were performed on gastric epithelial layer. In the 1, 7, 14 and 21 days traffic noise exposure, basal and pentagastrin-stimulated gastric acid secretion increased compared to the control group (P<0.001), but a significant decrease was seen in hyperacidity in 28th days, in the both basal and stimulated states (P<0.05). Histological study showed that mucosal layer thickness of stomach increased, while the number of oxyntic glands and cell nuclei decreased. It seems that 1,7,14 and 21 days traffic noise increase gastric acid secretion, while 28 days traffic noise can induce adaptation.