Towards a shared method to classify contaminated territories in the case of an accidental nuclear event: the PRIME project

The analysis of the management of the accidentally radioactive contaminated areas such as those around Chernobyl nuclear power plant highlights the fact that the current spatial classification methods hardly help in recovering proper use of the contaminated territory. The cause is mainly to be searched for in the traditional construction of risks assessment methods; these methods rest on criteria defined by institutional experts, which are not applicable in practise because they are not shared by all the stakeholders involved in the management of the contaminated territories. Opposite such top-down tentative management, local efforts supported by Non-Governmental Organizations to restore life in the contaminated area seem to be more fruitful but very time and resources consuming and limited to the specific areas where they are experimented. The aim of the PRIME project, in progress at the French Institute for Radioprotection and Nuclear Safety, is to mix the advantages of both approaches in building a multicriteria decision tool based on the territorial specificities. The criteria of the method are chosen and weighted with representatives of the territory’s stakeholders (decision makers, local actors and experts) to warrant that all the points of view are taken into account and to enable the risk managers to choose the appropriate strategy in case of an accident involving radioactive substances. The area chosen for the pilot study is a 50 km radius territory around the nuclear sites of Tricastin-Pierrelatte in the lower valley of Rhône (France). One of the exploration questions of the PRIME project is whether a multicriteria method may be an appropriate tool to treat the data and make them visible and accessible for all the stakeholders

Focal Spot, Winter 2006/2007

https://digitalcommons.wustl.edu/focal_spot_archives/1104/thumbnail.jp

Audit on the use of radiological investigations in the management of rhinosinusitis

Objectives: The aim of this audit is to establish the cost to the Maltese health system from the use of radiological imaging in managing rhinosinusitis and to identify areas in which these costs can be minimised by following guidelines on the management of rhinosinusitis. Methods: All plain radiographs and computed tomography scans (CT) of the paranasal sinuses requested in the Mater Dei Hospital over a one year period were analysed. Data was collected regarding: the quantity of investigations ordered, age of the patients, cost and requesting department. Results: Over one year: 205 CT scans and 113 sets of plain radiographs of the paranasal sinuses were requested, costing a total of euro103,440. The majority (73%) were elective requests made by ENT consultants. Five percent of CT scans were requested for patients less than 10 years of age. Conclusion: Rhinosinusitis is diagnosed clinically, only requiring radiological investigation in more complex cases best managed by specialists in ENT. Plain radiographs have limited use in the management of rhinosinusitis. Judicious use of imaging requests whilst following clinical guidelines is required to save money and minimise patient exposure to ionising radiation.peer-reviewe

Historical Development of the Linear Nonthreshold Dose-Response Model as Applied to Radiation

[Excerpt] Despite the nearly universal adoption of the linear nonthreshold dose response model (LNT) as the primary basis for radiation protection standards for the past half century, the LNT remains highly controversial and a contentious topic of discussion among health physicists, radiation biologists, and other radiological scientists. Indeed, it has been pointed out that the LNT has assumed the status of a paradigm, synonymous with an ideal, standard, or paragon or perhaps to some, a sacred cow. Reduced to its very basics, the LNT postulates that every increment of ionizing radiation dose, however small, carries with it a commensurate increase in the chance or risk that the exposed individual will suffer some undesirable radiation effect, and that the risk thus incurred is directly proportional or linearly related to the dose. The specific effects are termed “stochastic,” which has been defined as “of a random or statistical nature.” Stochastic or probabilistic effects of radiation may occur as a result of low doses and are generally taken to be cancers (including leukemias) and genetic defects in the progeny. The severity of these radiation-induced stochastic effects, should they occur, are independent of the dose that produced them; thus, even though the likelihood or probability of an occurrence may be small to negligible, any and all manifestations of a radiation induced stochastic effect will have equal severity. By contrast, higher doses of radiation are known to produce characteristic somatic or deterministic effects including erythema, epilation, sterility, diminution of blood cell counts, cataracts and, in very high exposures, acute and chronic radiation syndromes. Such frank biological effects are nonstochastic in nature (in fact, they were at one time termed “nonstochastic effects”) and will always be manifested once a particular minimum dose – i.e., a “threshold” – has been received. The severity of the effect is related to the dose. Below the threshold dose there will be no demonstrable effect; as the dose increases beyond the threshold, so does the severity of the effect, or the degree of harm. … The purpose of the above discussion is to illustrate the underlying controversy and confusion that surrounds the LNT today, as well to underscore the lack of precision that sometimes accompanies the arguments of both the proponents and opponents of the LNT. Given that the LNT is a low dose phenomenon, there needs to at least be consensus on what is low dose, and such a consensus needs also to include consideration of other relevant and important factors such as the dose rate and specific stochastic end point (i.e., type of cancer or mutation). With this as a backdrop, the historical development and gyrations that led to the LNT as it is currently applied (or, some would say, misapplied) in radiological protection can be examined in the context of current scientific thinking with respect to radiation effects. It is not the purpose of this paper to endorse any particular position or to take sides but rather to present the story in a factual and fair minded manner. Hopefully, what follows will successfully achieve this goal. Thus, this paper will briefly review the scientific bases and supporting studies that led to the development and acceptance of the LNT in health physics. It will briefly touch on such topics as hormesis and other studies, such as the classic work of the late Robley Evans, that clearly demonstrate a threshold and nonlinear response for certain stochastic effects such as osteogenic sarcoma, along with the plethora of studies that suggest or have been interpreted to indicate that for at least some end points (i.e., cancers), response to ionizing radiation is consistent with the LNT model

Drop-out rate from the liver transplant waiting list due to HCC progression in HCV-infected patients treated with direct acting antivirals.

BACKGROUND & AIM: concerns about an increased hepatocellular carcinoma (HCC) recurrence rate following directly acting antiviral (DAA) therapy in cirrhotic patients with a prior complete oncological response have been raised. Data regarding the impact of HCV-treatment with DAAs on waiting list drop-out rates in patients with active HCC and HCV-related cirrhosis awaiting liver transplantation (LT) are lacking. MATERIALS AND METHODS: HCV-HCC patients listed for LT between January 2015 and May 2016 at Padua Liver Transplant Centre were considered eligible for the study. After enrollment patients were divided into 2 groups, depending on whether they underwent DAAs treatment while awaiting LT or not. For each patient clinical, serological and virological data were collected. HCC characteristics were radiologically evaluated at baseline and during follow-up (FU). For transplanted patients, pathological assessment of the explants was performed and recurrence-rates were calculated. RESULTS: twenty-three patients treated with DAAs and 23 controls were enrolled. HCC characteristics at time of LT-listing were comparable between the 2 groups. Median FU was 10 and 7 months, respectively, during which 2/23 (8.7%) and 1/23 (4.3%) drop-out events due to HCC-progression were registered (p = 0.9). No significant differences in terms of radiological progression were highlighted (p = 0.16). Nine out of 23 cases (39%) and 14/23 (61%) controls underwent LT, and histopathological analysis showed no differences in terms of median number and total tumor volume of HCC nodules, tumor differentiation or microvascular invasion. During post-LT FU, 1/8 DAAs treated patient (12,5%) and 1/12 control (8,3%) experienced HCC recurrence (p = 0.6). CONCLUSIONS: Viral eradication does not seem to be associated with an increased risk of drop-out due to neoplastic progression in HCV-HCC patients awaiting LT

Evaluation of A Post-Treatment Follow-Up Program in Patients with Oral Squamous Cell Carcinoma

Objectives The duration and the frequency of follow-up after treatment of oral squamous cell carcinoma are not standardized in the current literature. The purpose of this study was to evaluate our local standard post-treatment and follow-up protocol. Materials and methods Overall, 228 patients treated curatively from 01/2006 to 07/2013 were reviewed. To evaluate the follow-up program, data on the secondary event were used. To determine risk groups, all patients with tumor recurrence were specifically analyzed. Relapse-free rate were estimated by the Kaplan-Meier product limit method. The chi-square test was used to identify independent risk factors for tumor relapse. Results In total, 29.8 % patients had a secondary event. The majority of the relapse cases (88.2 %) were detected within 2 years postoperatively, 61.8 % of them within the first year. Most events were local recurrences (34.7 %). UICC-stage IV was significantly associated with tumor recurrence (p = 0.001). Gender (p = 0.188), age (p = 0.195), localization (p = 0.739), T-stage (p = 0.35), N-stage (p = 0.55), histologic grade (p = 0.162), and tobacco and alcohol use (p = 0.248) were not significantly associated with tumor recurrence. Patients with positive neck nodes relapsed earlier (p = 0.011). The majority of relapses (86.3 %) were found in asymptomatic patients at routine follow-up. Conclusions The results of this study suggest an intensified follow-up within the first 2 years after surgery. Clinical relevance Given the higher relapse rate of patients exhibiting an UICC-stage IV and/or positive neck nodes, it seems to be from special interest to perform in this group a risk-adapted follow-up with monthly examinations also in the second year

MRI-based Surgical Planning for Lumbar Spinal Stenosis

The most common reason for spinal surgery in elderly patients is lumbar spinal stenosis(LSS). For LSS, treatment decisions based on clinical and radiological information as well as personal experience of the surgeon shows large variance. Thus a standardized support system is of high value for a more objective and reproducible decision. In this work, we develop an automated algorithm to localize the stenosis causing the symptoms of the patient in magnetic resonance imaging (MRI). With 22 MRI features of each of five spinal levels of 321 patients, we show it is possible to predict the location of lesion triggering the symptoms. To support this hypothesis, we conduct an automated analysis of labeled and unlabeled MRI scans extracted from 788 patients. We confirm quantitatively the importance of radiological information and provide an algorithmic pipeline for working with raw MRI scans