[Interest of robotic stereotactic radiosurgery in the management of brain metastases: Results of a retrospective, single center analysis]. / Place de la radiochirurgie stéréotaxique robotisée dans la prise en charge des métastases cérébrales : résultats d'une analyse rétrospective monocentrique.

PURPOSE: The management of malignant brain metastases becomes a main issue for the treatment of patients, because of the survival extension related to the improvement in systemic treatments. Robotic stereotactic radiosurgery (RSR) is a new approach in this indication. The purpose of this analysis was to define the efficacy of RSR, in order to determine prognostic factors of survival and factors of response. PATIENTS AND METHODS: It was a retrospective, single center (polyclinique de Bordeaux Nord Aquitaine) analysis performed from 2012 to 2015, involving patients with malignant brain metastases treated by RSR using the Cyberknife® technique. We analyzed the following parameters: response to RSR, prognostic and predictive factors of response, and survival. RESULTS: A total of 72 RSRs were performed among 55 analyzed patients; 62 treatments were assessable with a median follow-up of 9.4 months. The main delivered dose on the 80%-isodose was 20Gy. A complete response was achieved in 40.3% of patients (stability or regression=83.9%). The overall survival was 13 months. The risk of failure was significantly correlated with the increase in metastasis size and non-adenocarcinoma histology. A performance status<2 was the main prognostic factor of survival. CONCLUSIONS: The RSR allowed treating 3 to 5 brain metastases, avoiding an entire brain irradiation, and maintaining survival and quality of life.

Assessing the impact of dairy waste lagoons on groundwater quality using a spatial analysis of vadose zone and groundwater information in a coastal phreatic aquifer.

Dairy waste lagoons are considered to be point sources of groundwater contamination by chloride (Cl(-)), different nitrogen-species and pathogens/microorganisms. The objective of this work is to introduce a methodology to assess the past and future impacts of such lagoons on regional groundwater quality. The method is based on a spatial statistical analysis of Cl(-) and total nitrogen (TN) concentration distributions in the saturated and the vadose (unsaturated) zones. The method provides quantitative data on the relation between the locations of dairy lagoons and the spatial variability in Cl(-) and TN concentrations in groundwater. The method was applied to the Beer-Tuvia region, Israel, where intensive dairy farming has been practiced for over 50 years above the local phreatic aquifer. Mass balance calculations accounted for the various groundwater recharge and abstraction sources and sinks in the entire region. The mass balances showed that despite the small surface area covered by the dairy lagoons in this region (0.8%), leachates from lagoons have contributed 6.0% and 12.6% of the total mass of Cl(-) and TN (mainly as NO3(-)-N) added to the aquifer. The chemical composition of the aquifer and vadose zone water suggested that irrigated agricultural activity in the region is the main contributor of Cl(-) and TN to the groundwater. A low spatial correlation between the Cl(-) and NO3(-)-N concentrations in the groundwater and the on-land location of the dairy farms strengthened this assumption, despite the dairy waste lagoon being a point source for groundwater contamination by Cl(-) and NO3(-)-N. Mass balance calculations, for the vadose zone of the entire region, indicated that drying of the lagoons would decrease the regional groundwater salinization process (11% of the total Cl(-) load is stored under lagoons). A more considerable reduction in the groundwater contamination by NO3(-)-N is expected (25% of the NO3(-)-N load is stored under lagoons). Results demonstrate that analyzing vadose zone and groundwater data by spatial statistical analysis methods can significantly contribute to the understanding of the relations between groundwater contaminating sources, and to assessing appropriate remediation steps.

Infiltration mechanism controls nitrification and denitrification processes under dairy waste lagoon.

Earthen waste lagoons are commonly used to store liquid wastes from concentrated animal feeding operations. The fate of ammonium (NH) and nitrate (NO) was studied in the vadose zone below earthen-clay dairy farm waste lagoons using three independent vadose zone monitoring systems. The vadose zone was monitored from 0.5 to 30 m below land surface through direct sampling of the sediment porewater and continuous measurement of the sediment profile's water content variations. Four years of monitoring revealed that wastewater infiltration from the lagoon is controlled by two mechanisms: slow (mm d), constant infiltration from the lagoon bed; and rapid (m h) infiltration of wastewater and rainwater via preferential flow in desiccation cracks formed in the unsaturated clay sediment surrounding the lagoon banks. The preferential flow mechanism is active mainly during wastewater-level fluctuations and intensive rain events. The vadose zone below the waste sources remained unsaturated throughout the monitoring period, and all infiltrating NH was oxidized in the upper 0.5 m. The NH oxidation (nitrification) was coupled with NO reduction (denitrification) and depended on the sediment water content, which was controlled by the infiltration mechanism. Coupled nitrification-denitrification (CND) resulted in 90 to 100% reduction in the total nitrogen mass in the vadose zone, with higher removal under high water content (∼0.55 m m). Mass balance of nitrogen and isotopic composition of NO indicated that CND, rather than cation exchange capacity, is the key factor regulating nitrogen's fate in the vadose zone underlying earthen waste lagoons.

Biodegradation of explosives mixture in soil under different water-content conditions.

Soil redox potential plays a key role in the rates and pathways of explosives degradation, and is highly influenced by water content and microbial activity. Soil redox potential can vary significantly both temporally and spatially in micro-sites. In this study, when soil water content increased, the redox potential decreased, and there was significant enhancement in the biodegradation of a mixture of three explosives. Whereas TNT degradation occurred under both aerobic and anaerobic conditions, RDX and HMX degradation occurred only when water content conditions resulted in a prolonged period of negative redox potential. Moreover, under unsaturated conditions, which are more representative of real environmental conditions, the low redox potential, even when measured for temporary periods, was sufficient to facilitate anaerobic degradation. Our results clearly indicate a negative influence of TNT on the biodegradation of RDX and HMX, but this effect was less pronounced than that found in previous slurry batch experiments: this can be explained by a masking effect of the soil in the canisters. Fully or partially saturated soils can promote the existence of micro-niches that differ considerably in their explosives concentration, microbial community and redox conditions.

Sequential biodegradation of TNT, RDX and HMX in a mixture.

We describe TNT's inhibition of RDX and HMX anaerobic degradation in contaminated soil containing indigenous microbial populations. Biodegradation of RDX or HMX alone was markedly faster than their degradation in a mixture with TNT, implying biodegradation inhibition by the latter. The delay caused by the presence of TNT continued even after its disappearance and was linked to the presence of its intermediate, tetranitroazoxytoluene. PCR-DGGE analysis of cultures derived from the soil indicated a clear reduction in microbial biomass and diversity with increasing TNT concentration. At high-TNT concentrations (30 and 90 mg/L), only a single band, related to Clostridium nitrophenolicum, was observed after 3 days of incubation. We propose that the mechanism of TNT inhibition involves a cytotoxic effect on the RDX- and HMX-degrading microbial population. TNT inhibition in the top active soil can therefore initiate rapid transport of RDX and HMX to the less active subsurface and groundwater.

"Phytoscreening": the use of trees for discovering subsurface contamination by VOCs.

We tested the possibility of using tree cores to detect unknown subsurface contamination by chlorinated volatile organic compounds (Cl-VOCs) and petroleum hydrocarbons, a method we term "phytoscreening". The scope and limitations of the method include the following: (i) a number of widespread Cl-VOC contaminants are readily found in tree cores, although those with very high vapor pressures or low boiling points may be absent; (ii) volatile petroleum hydrocarbons were notwell-expressed in tree cores; (iii) trees should be sampled during active evapotranspiration and from directions that are well exposed to sunlight; (iv) there is not necessarily a direct correlation between concentrations measured in tree cores and those in the subsurface; (v) detection of a contaminant in a tree core indicates that the subsurface is contaminated with the pollutant; (vi) many possible causes of false negatives may be predicted and avoided. We sampled trees at 13 random locations in the Tel Aviv metropolitan area and identified Cl-VOCs in tree coresfromthree locations. Subsequently, subsurface contamination at all three sites was confirmed. Phytoscreening is a simple, fast, noninvasive, and inexpensive screening method for detecting subsurface contamination, and is particularly useful in urban settings where conventional methods are difficult and expensive to employ.

[Volume-effect in radiation therapy part one: volume-effect and tumour]. / L'effet volume en radiothérapie première partie: effet volume et tumeur.

Volume is an important parameter of radiation therapy. Local control is inversely related to tumor size and the complication rate increases with the importance of the irradiated volume. Although the effect of irradiated volume has been widely reported since the beginning of radiotherapy, it has been less studied than other radiation parameters such as dose, fractionation, or treatment duration. One of the first organ system in which the adverse effect of increased volume was well defined is the skin. Over the last twenty years, numerous mathematical models have been developed for different organs. In this report we will discuss the relation between irradiated volume and tumor control. In a second article we will study the impact of irradiated volume on radiation adverse effects.

Analytical procedure for simultaneous use of seven fluorobenzoates in multitracer tests.

An analytical procedure allowing simultaneous use of seven fluorobenzoate (FBA) isomers was developed and examined through column and field tracer experiments. The analytical method, based on high performance liquid chromatography (HPLC), included a reverse-phase separation method. This method was found to be very efficient for the FBA analysis, allowing accurate determination of seven FBAs in a single HPLC run, while avoiding analytical interference of other natural water constituents or pollutants. Consequently, this separation method allows the simultaneous use of seven isomers in multitracer tests in highly saline or contaminated environments. The mobility properties of the FBAs were examined in percolation experiments through a column filled with a mixture of crushed chalk and common fracture filling and coating material. The FBAs behaved conservatively as compared to bromid. All seven FBA isomers were successfully used in a multitracer test in a field percolation experiment designed to identify flowpath along a fracture plane.

[Fractionated radiotherapy of intracranial meningiomas: 15 years' experience at the Bordeaux University Hospital Center]. / Radiothérapie fractionnée des méningiomes intracrâniens: 15 ans d'expérience au centre hospitalier universitaire de Bordeaux.

PURPOSE: To evaluate the long-term results of external fractionated radiation therapy (RT) in the treatment of intracranial meningiomas. PATIENTS AND METHODS: From January 1981 to December 1996, 156 patients with intracranial meningiomas were treated with external fractionated RT. Median age was 57. Indications for radiation therapy were as follows: (1) completely excised histologically aggressive tumors (12 patients); (2) incomplete surgical resection (37 patients); (3) medically inoperable or basilar tumors where operation would involve considerable danger or permanent neurological damage (77 patients); and, (4) tumor recurrences (30 patients). Most patients were irradiated with 6 to 9 MV photon beams. A three to four-field technique with coned-down portals was used. Since 1993, 71 patients had a three dimensional dosimetry. Doses were calculated on the 95% or 98% isodoses, all fields were treated every day, five days a week, for a median total dose of 50 Gy (1.8 Gy/Fraction). RESULTS: Median follow-up from radiation therapy was 40 months. Acute tolerance was excellent; an early clinical improvement during radiation therapy was noted in 19 patients (17.8%). Clinical improvement or stabilization was observed in 130 patients (83.4%). Radiologically, local control was obtained in 124 cases (79.4%) and tumor recurrences occurred in 21 cases (ten progressions in the treated volume, five borderline, six new locations). Overall and cause specific-survival rates were 75% and 89% at five years, and 45 and 76% at 10 years, respectively. CONCLUSION: These results reassess the role of fractionated RT in the treatment of intracranial meningiomas. Long-term tolerance is excellent for a majority of patients. The study of recurrences confirms the importance of the definition of the target volume, and asks questions about total given doses.

[Central nervous system. Experience of the Bordeaux University Hospital Center and review of the literature]. / Les dysgerminomes du système nerveux central. Expérience du Centre Hospitalier Universitaire de Bordeaux et analyse de la littérature.

PURPOSE: Retrospective analysis of 17 patients with intracranial germ cell tumors treated in a multidisciplinary consultation at the Bordeaux University Hospital a and literature review. MATERIALS AND METHODS: Seventeen consecutive patients were treated from 1978 to 1995 for a primary intracranial germ cell tumor. Median age was 14 (range 3-29 years). There were two malignant teratoma, six proved germinoma and nine presumed germinoma (diagnostic based on biological, radiological and treatment criteria). All received radiotherapy from 30 to 60 Gy (median 40 Gy) in different volumes. Chemotherapy was administered in 15 cases, three after surgery and 12 after radiotherapy. RESULTS: All tumours were in complete remission after initial treatment. The two malignant teratomas recurred in non-irradiated area after nine and 48 months, and the patients died. None of the germinoma recurred within a follow-up period of two to 17 years (median 65 months). Five and 10 year actuarial overall survival rates were the same: 84% for all histologies and 100% for germinomas. Only two patients developed school difficulties and six presented an hypopituitarism, of which one was consecutive to radiotherapy. Chemotherapy was well tolerated. CONCLUSION: This retrospective study and literature analysis are in favor of limited dose and volume of radiation therapy associated with chemotherapy.

[Practice of virtual simulation at the Saint-André hospital]. / Pratique de la simulation virtuelle à l'hôpital Saint-André.

PURPOSE: Prospective evaluation of a virtual simulation technique. PATIENTS AND METHODS: From September 1993 to February 1997, 343 patients underwent radiation therapy using this technique. Treated sites were mostly: brain (132), rectum (59), lung (43), and prostate (28). A CT-scan was performed on a patient in treatment position. Twenty-five to 70 jointive slices widely encompassed the treated volume. The target volume (CTV according to ICRU 50) and often critical organs were controured, slice by slice, by the radiation oncologist. Beams covering the CTV plus a security margin (PTV) were placed on the "virtual patient". Digital radiographs were reconstructed (DRR) as simulator radiographs for each field. Thus, the good coverage of PTV was assessed. Fields and beam arrangements were further optimized. Definitive isocenter was then placed using a classical simulator. Perfect matching of DRR and actual simulator radiographs had to be obtained. RESULTS: Nineteen patients presented grade 3, and 1 grade 4 acute radiation effects. With a median follow-up of 18 months, five patients suffered from grade 3, and one from grade 4 complications. Fifty-five patients had tumor recurrence in the treated volume, and 19 had marginal relapse. CONCLUSION: In our department, virtual simulation has become a routine technique of treatment planning for deep-seated tumors. This technique remains time-consuming for radiation oncologists: about 2 hours. But it stimulates reflexion on anatomy, tumor extension pathways, target volumes; and is becoming an excellent pedagogical tool.

[Routine use of electronic portal imaging. Positioning verification in 922 successive pelvic fields]. / Utilisation en routine du portal imaging électronique. Vérification de mise en place de 922 champs pelviens successifs.

Treatment reproducibility is a major criterion of quality assurance in radiation therapy. During each course, the same dose should be delivered in the same volume of irradiation. Today, portal imaging devices can be used routinely to check and correct patient positioning before much of the daily irradiation has been delivered. In this study we used the Portal Vision Varian (PVV) system during pelvic irradiation in 16 patients. This device can automatically acquire portal images in the first seconds of each course. Observed discrepancies are directly classified by the radiation oncologist according to their type (cranio-caudal, lateral, antero-posterior) and severity (correction of patient positioning is necessary or not). In case of error, patient positioning is corrected before the end of irradiation. Of the 922 portals analysed with PVV, 901 could be analysed (97%). Two hundred and ninety-nine positioning discrepancies were observed (33%) with 59 of them leading to correction (6%). Most of the time, these errors concerned antero-posterior portals. Finally, each patient had an average of 18 to 19 discrepancies which were mainly of no importance for treatment quality. Nevertheless, real errors leading to correction were observed in 14 patients (88%) with an average of four per patient. In some patients many errors occurred, while in others only a few. These shifts were not related to patient weight and thickness but probably a portal dimension. In summary, we think that during pelvic irradiation a portal imaging device should be used daily to improve treatment quality. This system can help the radiation oncologist to discover many positioning errors (an average of four) in the majority of patients (88%) and to correct them before the end of irradiation.