The U.S. Environmental Protection Agency (EPA) has not published a 30-d average or continuous criterion for silver due to the apparent toxicity of this element and the lack of available chronic exposure data. The present study examined acute effects on nine species representative or indigenous to the New River, Virginia, and sublethal effects on three of those species using the Resident Species Approach. Our results showed that invertebrates were much more sensitive to silver than fish, including juvenile rainbow trout (Oncorhynchus mykiss). Hya/e//u aztecu (amphipod) was the most sensitive species followed by the mayflies Stenonema sp. and Isonychia bicolor and the stonefly Leuctra sp. The Final Acute Value in this study was 1.32 pg/L total recoverable silver. In sublethal tests, Isonychia growth, as measured by the number of molts over time, was the most sensitive effect observed. Estimated acute:"chronic" ratios ranged from two to 34 with Corbicula fluminea having the largest ratio. Our study results, along with available published data, suggested a Final Chronic Value of 0.13 pg/L total silver which is approximately one-half the level obtained using the EPA acute formula and ambient water hardness. Our results suggest that a continuous criterion for silver may be predictable using the hardness-dependent formula and a safety factor of 0.5.
Background and purposeIn radiotherapy (RT) bolus material is used to increase skin dose and eliminate the ‘skin-sparing’ effect. Bolus fabrication is limited to the expertise of the practitioner and is time and resource intensive for both patients and staff to construct bolus. In addition, prefabricated bolus does not always conform to irregular surfaces resulting in variations to dose distribution at the skin surface. The purpose of this paper is to ascertain whether it is feasible to improve bolus conformity within radiation therapy by using a 3D printer to fabricate bolus.MethodA literature review was conducted that utilised Boolean terminology and included keywords; (‘3d’ OR ‘3-dimensional’ OR ‘three dimensional’) ‘bolus’ OR ‘boli’ conform*, (‘Radiation therapy’ OR ‘radiotherapy’) Printing.ResultsSeveral key papers were identified and critically evaluated based of the title of the feasibility of improving bolus conformity with the used of 3D printing. Several fabrication material devices were explored.FindingsThe literature advocates that fused deposition modelling fabrication device clear polylactic acid material to be an adequate product to construct 3D printed bolus and conform to irregular surfaces. 3D bolus would prove advantageous for volumetric arc therapy/intensity modulated radiation therapy techniques as literature has shown the presence of air gaps, small field sizes and large beam obliquity can result in a >10% dose reduction at skin surface.
The aim of the study was to present a case of clinically diagnosed glomus vagale in a 42-year-old Aboriginal woman treated with external beam radiotherapy and to carry out a review of the published work. The details of presentation, diagnosis, treatment and follow up of the patient are discussed. A review of the published work was carry out using MEDLINE database with respect to aetiology, clinical presentation, diagnosis, treatment and expected outcomes. Glomus vagale tumours are a subtype of paragangliomas of the head and neck derived from extra-adrenal paraganglia of the autonomic nervous system. They are typically slow-growing, benign masses that are often asymptomatic and rarely show signs of hypersecretion. Treatment options include embolization, surgical excision, radiotherapy or surveillance. Radiotherapy is often used for extensive lesions where surgery is considered prohibitively morbid. Following treatment relapse rates are low with the most patients achieving long-term control. Our patient presented with an extensive lesion compressing the wall of the carotid artery and invading the jugular fossa to involve the clivus. Surgery was offered; however, the patient opted for external beam radiotherapy. A dose of 45 Gy in 25 fractions was delivered with 6-MV photons employing a CT-planned, wedge pair technique. Glomus vagale tumours are rare and should be managed in a multidisciplinary head and neck clinic with both surgical and radiation oncology opinions offered. The toxicities and outcomes of both methods should be discussed.
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