The Health Physics Society (HPS) conceived of the idea of an online "Ask the Experts" (ATE) feature in 1999 when the Society created its website. ATE features are popular now, but at that time it was a novel idea, so there was no assurance it would succeed. Now 20 y later, the HPS considers its ATE feature a success and the most valuable service the Society offers for the public. Nearly 13,000 questions have been submitted to the feature. They come both from members of the public and from health physicists. All have been answered personally by radiation safety experts. While it is important to answer questions personally, it is recognized that the most far-reaching impact of the feature is the written material on the ATE section of the website, which is provided for people searching for answers to their concerns and questions. Posted material includes frequently asked questions, summary papers on topics of interest, and links to other pertinent information. This is in addition to answers to a select group of submitted questions. To enhance the information search, all postings, including answers to questions, have headlines. These serve as keywords that facilitate website searches. The feature, managed by one lead editor, 20 topic editors, and more than 300 experts, draws over one million visitors per year. This statistic suggests that a substantial number of people are finding answers to their questions on the site and, therefore, do not need to submit personal questions. ATE editors have learned much about effective interaction with questioners, especially members of the public. Most important, answers should show compassion, present the bottom line first, be brief, and use plain language. Heavy reliance on peer-reviewed documents adds to the credibility of the information. Questions from the public cover a wide range of subjects; however, by far the most frequent deal with medical exposures, especially computed tomography procedures. Other questions deal with a wide range of concerns including products from Japan, granite countertops, radon, smoke detectors, luggage and whole-body scanners, and radiation exposure from airline travel. Another major concern is exposure to nonionizing radiation sources such as cell phones, radar, ultraviolet radiation, lasers, and power lines. Examples are provided of the most intriguing questions that have come to the ATE feature and the answers provided by the experts.

Breast cancer radiotherapy increases the risk of heart failure with preserved ejection fraction (HFpEF). Cardiomyocytes are highly radioresistant, but radiation specifically affects coronary microvascular endothelial cells, with subsequent microvascular inflammation and rarefaction. The effects of radiation on left ventricular (LV) diastolic function are poorly characterized. We hypothesized that cardiac radiation exposure may result in diastolic dysfunction without reduced EF. Global cardiac expression of the sodium-iodide symporter (NIS) was induced by cardiotropic gene (adeno-associated virus serotype 9) delivery to 5-wk-old rats. SPECT/CT (125I) measurement of cardiac iodine uptake allowed calculation of the 131I doses needed to deliver 10- or 20-Gy cardiac radiation at 10 wk of age. Radiated (Rad; 10 or 20 Gy) and control rats were studied at 30 wk of age. Body weight, blood pressure, and heart rate were similar in control and Rad rats. Compared with control rats, Rad rats had impaired exercise capacity, increased LV diastolic stiffness, impaired LV relaxation, and elevated filling pressures but similar LV volume, EF, end-systolic elastance, preload recruitable stroke work, and peak +dP/d t. Pathology revealed reduced microvascular density, mild concentric cardiomyocyte hypertrophy, and increased LV fibrosis in Rad rats compared with control rats. In the Rad myocardium, oxidative stress was increased and in vivo PKG activity was decreased. Experimental cardiac radiation exposure resulted in diastolic dysfunction without reduced EF. These data provide insight into the association between cardiac radiation exposure and HFpEF risk and lend further support for the importance of inflammation-related coronary microvascular compromise in HFpEF. NEW & NOTEWORTHY Cardiac radiation exposure during radiotherapy increases the risk of heart failure with preserved ejection fraction. In a novel rodent model, cardiac radiation exposure resulted in coronary microvascular rarefaction, oxidative stress, impaired PKG signaling, myocardial fibrosis, mild cardiomyocyte hypertrophy, left ventricular diastolic dysfunction, and elevated left ventricular filling pressures despite preserved ejection fraction.

Background and purpose: Health leaders have advocated for incident learning systems (ILSs) to prevent errors, but there is limited evidence demonstrating that ILSs improve cancer patient safety. Herein, we report a long-term retrospective review of ILS reports for the brachytherapy practice at a large academic institution.Material and methods: Over a nine-year period, the brachytherapy practice was encouraged to report all standard operating procedure deviations, including low risk deviations. A multidisciplinary committee assigned root causes and risk scores to all incidents. Evidence based practice changes were made using ILS data, and relevant incidents were communicated to all staff in order to reduce recurrence rates.Results: 5258 brachytherapy procedures were performed and 2238 incidents were reported from 2007 to 2015. A ramp-up period was observed in ILS participation between 2007 (0.12 submissions/procedures) and 2011 (1.55 submissions/procedures). Participation remained stable between 2011 and 2015, and we achieved a 60% (p < 0.001) decrease in the risk of dose error or violation of radiation safety policy and a 70% (p < 0.001) decrease in frequency of high composite-risk scores. Significant decreases were also observed in incidents with root causes of poor communication (60% decrease, p < 0.001) and poor quality of written procedures (59% decrease, p < 0.001).Conclusions: Implementation of an ILS in brachytherapy significantly reduced risk during cancer patient care. Safety improvements have been sustained over several years. (C) 2017 The Authors. Published by Elsevier Ireland Ltd.

Comparison between the BrachyVision calculated dose and dosimeter measurement was performed using CERR radiotherapy analysis software.Results: The dosimeter was reconstructed with 1 mm voxel spacing and a 3pixel median filter.Aside from the needle track itself, no fractures formed in the dosimeter from the insertion, resulting in a pristine readout free of major image artifacts.Line profiles show strong agreement between the calculated and measured doses across the entire distribution, with exceptionally high matching at the sharp gradients surrounding the site of insertion (Fig. 1).Gamma index calculation shows 99.9% of voxels passing at 3%/2mm criteria.Conclusions: This work introduces a new formulation of low-durometer, deformable Presage dosimeters, and demonstrates strong viability for their use in complete 3D validation of interstitial brachytherapy treatments.These dosimeters are able to address a growing need in brachytherapy dose planning, quality control, and likely treatment commissioning.Further work will test this dosimeter formulation with multiple needle insertions, anthropomorphically-correct anatomy, and varying deformation to closer represent real-life treatment scenarios.

Introduction: Comorbidity-driven, coronary microvascular endothelial inflammation may be the fundamental pathophysiologic mechanism in heart failure with preserved ejection fraction (HFpEF). Cardiomyocytes are resistant to radiation but radiation specifically induces microvascular endothelial cell damage and inflammation. Hypothesis: Cardiac radiation exposure produces isolated coronary microvascular compromise (RMVC) and recapitulates the HFpEF phenotype. Methods: Cardiac expression of rat sodium iodide symporter (NIS) was induced by cardiotropic gene delivery (AAV9-NIS; 2*10 10 vg/rat, tail vein injection) to Sprague Dawley rats at age 5 wks. SPECT-CT (I 125 ) measured cardiac iodine uptake to calculate appropriate I 131 doses to deliver 10 or 20 Gy cardiac radiation at age 10 wks (+ chronic T 4 replacement). RMVC and Control rats were studied at age 30 wks. Results: Table. Body weight, heart rate and blood pressure were similar across groups. EF was similar but LV diastolic volume (EDV) tended to be smaller and treadmill exercise capacity was markedly reduced in RMVC. Invasive pressure-volume analysis showed increased LV diastolic stiffness (β) and LV end-diastolic (EDP), central venous (CVP) and mean circulatory filling (Mcfp) pressures but similar preload recruitable stroke work and peak +dP/dt in RMVC, consistent with isolated diastolic dysfunction. Pathology revealed similar heart weight but reduced microvascular density and increased LV fibrosis in RMVC. In RMVC myocardium, fetal gene expression (ANP mRNA) was increased and correlated inversely with microvascular density (p Conclusion: In the absence of pressure overload, isolated coronary microvascular compromise produces a HFpEF phenotype. This model may be useful for testing HFpEF therapeutic strategies targeting microvascular compromise and its sequella.

Mayo Clinic 200 First St., SW Rochester, MN 55905 19890 Fish Lake Lane Elysian, MN 56028 The author declares no conflicts of interest.

Dickson, Howard; Walchuk, Mary; Ryan, Michael T.; Little, Craig A.; Roessler, Genevieve S.; Classic, Kelly; Edwards, John Author Information

Purpose: To evaluate the radiation dose to a surgeon's hands during I-125 eye plaque procedures.Methods: Sixteen consecutive patients with uveal melanomas were scheduled for eye plaque brachytherapy. The same surgeon wore thermoluminescent dosimeters on the dominant index finger and thumb while placing and removing the eye plaque to measure radiation dose. Additional laboratory experiments were performed to measure unobstructed (by surgical gloves or other parts of the hand) radiation exposure from a plaque.Results: Hand radiation doses during eye plaque brachytherapy are very low, but measurable, with plaques containing an average of 1.3 GBq of I-125.Conclusion: Using these data, a surgeon would need to perform more than 1,000 cases each year to approach or exceed the annual regulatory radiation dose limits for the extremities. RETINA 32:1900-1905, 2012

Health Physics: December 2011 - Volume 101 - Issue 6 - p 643-644 doi: 10.1097/HP.0b013e318225c20b

OBJECTIVE:We have previously shown the therapeutic efficacy of an engineered oncolytic measles virus expressing the sodium iodide symporter reporter gene (MV-NIS) in mice with human pancreatic cancer xenografts. The goal of this study was to determine the synergy between MV-NIS-induced oncolysis and NIS-mediated (131)I radiotherapy in this tumor model. MATERIALS AND METHODS:Subcutaneous human BxPC-3 pancreatic tumors were injected twice with MV-NIS. Viral infection, NIS expression, and intratumoral iodide uptake were quantitated with (123)I micro-SPECT/CT. Mice with MV-NIS-infected tumors were treated with 0, 37, or 74 MBq (131)I and monitored for tumor progression and survival. Additional studies were performed with stable NIS-expressing tumors (BxPC-3-NIS) treated with 0, 3.7, 18.5, 37, or 74 MBq of (131)I. RESULTS:Mice treated with intratumoral MV-NIS exhibited significant tumor growth delay (p < 0.01) and prolonged survival (p = 0.02) compared with untreated mice. Synergy between MV-NIS-induced oncolysis and NIS-mediated (131)I ablation was not seen; however, a significant correlation was observed between NIS-mediated intratumoral iodide localization (% ID/g) and peak tumor volume reduction (p = 0.04) with combination MV-NIS and (131)I therapy. Stably transduced NIS-expressing BxPC-3 tumors exhibited rapid regression with > or = 18.5 MBq (131)I. CONCLUSION:Delivery of (131)I radiotherapy to NIS-expressing tumors can be optimized using micro-SPECT/CT imaging guidance. Significant hurdles exist for NIS as a therapeutic gene for combined radiovirotherapy in this human pancreatic cancer model. The lack of synergy observed with MV-NIS and (131)I in this model was not due to a lack of radiosensitivity but rather to a nonuniform intratumoral distribution of MV-NIS infection.

This paper describes a new technique to suture the radioactive plaque to sclera. The radioactive plaque is conventionally sutured to the sclera using 5/0 nylon sutures. The imbricated suture technique involves using a 1/0 silk or 2/0 mersilene suture imbricated with the 5/0 nylon suture when the nylon suture is tied and cut. The imbricated suture technique allows easy identification of the plaque at removal and provides a surface that separates the 5/0 nylon from the surface of the eyelet platform, making suture cutting easier and safer. The radiation exposure times ranged from 9.1 minutes to 14 minutes (mean: 10.8 minutes) during plaque insertion and from 2.8 to 3.3 minutes (mean: 3.0 minutes) during plaque removal with the imbricated suture technique. This technique may decrease radiation exposure time and may prevent inadvertent scleral damage.

Non-invasive imaging can provide essential information for the optimization of new drug delivery-based bone regeneration strategies to repair damaged or impaired bone tissue. This study investigates the applicability of nuclear medicine and radiological techniques to monitor growth factor retention profiles and subsequent effects on bone formation. Recombinant human bone morphogenetic protein-2 (BMP-2, 6.5 mu g/scaffold) was incorporated into a sustained release vehicle consisting of poly(lactic-co-glycolic acid) microspheres embedded in a poly(propylene fumarate) scaffold surrounded by a gelatin hydrogel and implanted subcutaneously and in 5-mm segmental femoral defects in 9 rats for a period of 56 days. To determine the pharmacokinetic profile, BMP-2 was radiolabeled with I-125 and the local retention of I-125-BMP-2 was measured by single photon emission computed tomography (SPECT), scintillation probes and ex vivo scintillation analysis. Bone formation was monitored by micro-computed tomography (mu CT). The scaffolds released BMP-2 in a sustained fashion over the 56-day implantation period. A good correlation between the SPECT and scintillation probe measurements was found and there were no significant differences between the non-invasive and ex-vivo counting method after 8 weeks of follow up. SPECT analysis of the total body and thyroid counts showed a limited accumulation of 1251 within the body. Ectopic bone formation was induced in the scaffolds and the femur defects healed completely. In vivo mu CT imaging detected the first signs of bone formation at days 14 and 28 for the orthotopic and ectopic implants, respectively, and provided a detailed profile of the bone formation rate. Overall, this study clearly demonstrates the benefit of applying non-invasive techniques in drug delivery-based bone regeneration strategies by providing detailed and reliable profiles of the growth factor retention and bone formation at different implantation sites in a limited number of animals. (C) 2008 Elsevier B.V. All rights reserved.

OBJECTIVE Our objectives were to, first, determine the oncolytic potential of an engineered measles virus expressing the sodium-iodide symporter gene (MV-NIS) for intratumoral (i.t.) therapy of pancreatic cancer and, second, evaluate NIS as a reporter gene for in vivo monitoring and quantitation of MV-NIS delivery, viral spread, and gene expression in this tumor model. MATERIALS AND METHODS Cultured human pancreatic cancer cells were infected with MV-NIS. Light microscopy, cell viability, and iodide uptake assays were used to confirm viral infection and NIS gene expression and function in vitro. Human pancreatic tumor xenografts were established in mice and infected via i.t. MV-NIS injections. NIS-mediated i.t. iodide uptake was quantitated by (123)I micro-SPECT/CT. i.t. MV-NIS infection was confirmed by immunohistochemistry of excised pancreatic xenografts. The oncolytic efficacy of MV-NIS was determined by measurement of tumor growth and mouse survival. RESULTS Infection of human pancreatic cancer cell lines with MV-NIS in vitro resulted in syncytia formation, marked iodide uptake, and ultimately cell death. Tumor xenografts infected with MV-NIS concentrated radioiodine, allowing serial quantitative imaging with (123)I micro-SPECT/CT. i.t. MV-NIS therapy of human pancreatic cancer xenografts resulted in a significant reduction in tumor volume and increased survival time of the treated mice compared with the control mice. CONCLUSION MV-NIS efficiently infects human pancreatic tumor cells and results in sufficient radioiodine uptake to enable noninvasive serial imaging and quantitation of the intensity, distribution, and time course of NIS gene expression. MV-NIS also shows oncolytic activity in human pancreatic cancer xenografts: Tumor growth is reduced and survival is increased in mice treated with the virus.

Health Physics: December 2009 - Volume 97 - Issue 6 - p 640 doi: 10.1097/HP.0b013e3181b8cf57

The purpose of this study was to develop and validate a screening method based on scintillation probes for the simultaneous evaluation of in vivo growth factor release profiles of multiple implants in the same animal. First, we characterized the scintillation probes in a series of in vitro experiments to optimize the accuracy of the measurement setup. The scintillation probes were found to have a strong geometric dependence and experience saturation effects at high activities. In vitro simulation of 4 subcutaneous limb implants in a rat showed minimal interference of surrounding implants on local measurements at close to parallel positioning of the probes. These characteristics were taken into consideration for the design of the probe setup and in vivo experiment. The measurement setup was then validated in a rat subcutaneous implantation model using 4 different sustained release carriers loaded with (125)I-BMP-2 per animal. The implants were removed after 42 or 84 days of implantation, for comparison of the non-invasive method to ex vivo radioisotope counting. The non-invasive method demonstrated a good correlation with the ex vivo counting method at both time-points of all 4 carriers. Overall, this study showed that scintillation probes could be successfully used for paired measurement of 4 release profiles with minimal interference of the surrounding implants, and may find use as non-invasive screening tools for various drug delivery applications.