Clinical Application of a Hybrid RapidArc Radiotherapy Technique for Locally Advanced Lung Cancer

OBJECTIVE

Radiation treatment planning for locally advanced lung cancer can be technically challenging, as delivery of ≥60 Gy to large volumes with concurrent chemotherapy is often associated with significant risk of normal tissue toxicity. We clinically implemented a novel hybrid RapidArc technique in patients with lung cancer and compared these plans with 3-dimensional conformal radiotherapy and RapidArc-only plans.

MATERIALS/METHODS

Hybrid RapidArc was used to treat 11 patients with locally advanced lung cancer having bulky mediastinal adenopathy. All 11 patients received concurrent chemotherapy. All underwent a 4-dimensional computed tomography planning scan. Hybrid RapidArc plans concurrently combined static (60%) and RapidArc (40%) beams. All cases were replanned using 3- to 5-field 3-dimensional conformal radiotherapy and RapidArc technique as controls.

RESULTS

Significant reductions in dose were observed in hybrid RapidArc plans compared to 3-dimensional conformal radiotherapy plans for total lung V20 and mean (-2% and -0.6 Gy); contralateral lung mean (-2.92 Gy); and esophagus V60 and mean (-16.0% and -2.2 Gy; all P < .05). Contralateral lung doses were significantly lower for hybrid RapidArc plans compared to RapidArc-only plans (all P < .05). Compared to 3-dimensional conformal radiotherapy, heart V60 and mean dose were significantly improved with hybrid RapidArc (3% vs 5%, P = .04 and 16.32 Gy vs 16.65 Gy, P = .03). However, heart V40 and V45 and maximum spinal cord dose were significantly lower with RapidArc plans compared to hybrid RapidArc plans. Conformity and homogeneity were significantly better with hybrid RapidArc plans compared to 3-dimensional conformal radiotherapy plans ( P < .05). Treatment was well tolerated, with no grade 3+ toxicities.

CONCLUSION

To our knowledge, this is the first report on the clinical application of hybrid RapidArc in patients with locally advanced lung cancer. Hybrid RapidArc permitted safe delivery of 60 to 66 Gy to large lung tumors with concurrent chemotherapy and demonstrated advantages for reduction in low-dose lung volumes, esophageal dose, and mean heart dose.

Leukemia Cutis of the Face, Scalp, and Neck Treated with Non-coplanar Split Field Volumetric Modulated Arc Therapy: A Case Report

Malignancies with a superficial involvement of the scalp present a unique technical challenge for radiation treatment planning. As an example of this, leukemic infiltration of the superficial skin as the only presentation of the disease is a rare entity. For such cases, radiation oncologists have typically treated with 3D conformal radiotherapy with matched electron fields, a technique that can lead to significant dose inhomogeneity. In this report, we describe the case of a patient with leukemia cutis with a superficial involvement of the scalp, face, and shoulders that was treated with volumetric modulated arc radiotherapy, with an impressive clinical response. 

50 Years of Environmental Monitoring at Henkel

The gradually increasing detergents consumption in Germany since 1950 resulted in higher emissions of their ingredients to the environment. The first generation of mineral oil-based surfactants, tetrapropylene benzene sulfonate (TPS), exhibited poor biodegradability and caused public environmental concerns. These prompted Henkel in 1958 to start a systematic measurement of some main detergent constituents in the river Rhine in Germany. Since then, a number of monitoring activities regarding the determination of detergent ingredients concentrations and freights in rivers and waste water treatment plants (WWTP) followed. This paper summarizes 50 years experience at Henkel in monitoring of detergent ingredients in the aquatic environment. The long-term monitoring results on the river Rhine provides an impressive record of the development of the environmental burden by surfactant emissions and of the gradual improvement of river water quality over time. The reasons for the changes are discussed. Further monitoring activities on WWTPs have shown for the first time, that domestic wastewater treatment plants (DWTP) are similarly suitable for the removal of surfactants like municipal ones. The good removal of prominent organic detergent ingredients was shown by several time-proportional sampling campaigns in municipal WWTPs. Finally the positive impact of the modernisation of a municipal WWTP on the chemical and biological water quality on a small river creek is reported over the time period of 7 years. All of the reported studies indicate a low environmental burden due to the use of detergents ingredients today. The learnings from the different activities in environmental monitoring by Henkel have contributed to a solid understanding of the fate of detergent ingredients in the environment. This in turn was the prerequisite for development of reliable exposure prediction models. Today, Henkel employs both, environmental monitoring and modeling instruments, for assessing the environmental exposure of chemicals.

Is the EU Ecolabel DID List a Useful Environmental Evaluation Tool for Detergent-like Consumer Products?

For comparing the environmental relevance of household and personal care products, the Critical Dilution Volume (CDV) originally developed for the EU Ecolabel of detergents is an often used key criterion. The EU Ecolabel Detergents Ingredient Database (DID) is a publicly available information basis for derivation of product CDV by providing data on key descriptors for the environmental fate and effects of chemical substances used in consumer products. The alterations of the CDV-relevant descriptors in the revised DID list (2004) have led, in many cases, to an unrealistic depiction of the environmental behaviour of product ingredients and to inadequate product evaluations. The paper reports on the framework of and the experiences with a novel DID list developed by an expert group of the German Hauptausschuss Detergentien (HAD) enabling an environmentally more realistic comparison of products.

Anaerobic Biodegradation of Surfactants – Scientific Review

The anaerobic biodegradation of surfactants is used as an acceptability criterion in some environmental pieces of legislation (eco-label, risk assessment, etc.), without a proper evaluation of the relevance of such a characteristic. Available screening test methods to assess the anaerobic biodegradation do not simulate the real conditions prevailing in these anaerobic compartments but rather reflect more stringent conditions, due to the high test substance/biomass ratio, possibility of inhibitory effects and limited possibility for adaptation. Therefore positive results are indicative of a similar behaviour under environmental conditions, while a negative result cannot be necessarily interpreted as inherent anaerobic recalcitrance. The majority of surfactants entering the environment will be exposed to and degraded under aerobic conditions, and only less than 20 % will potentially reach temporarily anaerobic environmental compartments. In contrast to the well documented adverse effects observed in the absence of aerobic biodegradation, the lack of anaerobic biodegradation does not seem to be correlated with any apparent environmental problem for most compartments after more than 40 years of widely use of such products. The scientific review concluded that anaerobic biodegradability does not have the same environmental relevance as the aerobic one. Anaerobic biodegradability should not, therefore, be used as a pass/fail property for the environmental acceptability of surfactants which are readily biodegradable under aerobic conditions.

A system for continual quality improvement of normal tissue delineation for radiation therapy treatment planning

PURPOSE

To implement the "plan-do-check-act" (PDCA) cycle for the continual quality improvement of normal tissue contours used for radiation therapy treatment planning.

METHODS AND MATERIALS

The CT scans of patients treated for tumors of the brain, head and neck, thorax, pancreas and prostate were selected for this study. For each scan, a radiation oncologist and a diagnostic radiologist, outlined the normal tissues ("gold" contours) using Radiation Therapy Oncology Group (RTOG) guidelines. A total of 30 organs were delineated. Independently, 5 board-certified dosimetrists and 1 trainee then outlined the same organs. Metrics used to compare the agreement between the dosimetrists' contours and the gold contours included the Dice Similarity Coefficient (DSC), and a penalty function using distance to agreement. Based on these scores, dosimetrists were re-trained on those organs in which they did not receive a passing score, and they were subsequently re-tested.

RESULTS

Passing scores were achieved on 19 of 30 organs evaluated. These scores were correlated to organ volume. For organ volumes <8 cc, the average DSC was 0.61 vs organ volumes ≥8 cc, for which the average DSC was 0.91 (P=.005). Normal tissues that had the lowest scores included the lenses, optic nerves, chiasm, cochlea, and esophagus. Of the 11 organs that were considered for re-testing, 10 showed improvement in the average score, and statistically significant improvement was noted in more than half of these organs after education and re-assessment.

CONCLUSIONS

The results of this study indicate the feasibility of applying the PDCA cycle to assess competence in the delineation of individual organs, and to identify areas for improvement. With testing, guidance, and re-evaluation, contouring consistency can be obtained across multiple dosimetrists. Our expectation is that continual quality improvement using the PDCA approach will ensure more accurate treatments and dose assessment in radiotherapy treatment planning and delivery.

Assessment of bioconcentration and secondary poisoning of surfactants

The relevance of the bioconcentration behaviour of surfactants for the secondary poisoning assessment and for the risk characterisation in the bird and mammalian food chain has been investigated. The approach used is described in the recently revised EU Technical Guidance Document for the Risk Assessment of Substances. The results demonstrate that, based on experimentally derived bioconcentration factors, environmental concentrations and effects in animals, there is a clear level of safety for both linear alkylbenzene sulphonate (LAS) and alcohol ethoxylates (AE), the most important surfactants by volume. To assess other surfactants used in detergents, a bioconcentration factor that would need to be attained for secondary poisoning to be of concern has been estimated from predicted environmental concentrations and known long-term effects data in animals. Based on the known structural similarity of these surfactants to LAS and AE and the ubiquitous nature of the enzymatic systems that are present in biotransformation processes in organisms, it is concluded that bioconcentration of these surfactants to these levels is highly unlikely. Therefore the potential for secondary poisoning effects of these surfactants is extremely low.

The time-window--an inadequate criterion for the ready biodegradability assessment of technical surfactants

The attainment of the biodegradation pass-level within a distinct time period (10 days after the end of the lag-phase) is one of the criteria for assessing the ready biodegradability of chemical substances. The time-window as a simple approach for describing biodegradation kinetics is a poor descriptor in the case of mixtures and poorly soluble compounds. Technically used surfactants are a mixture of numerous homologues and isomers and many are composed of two organic moieties which will be degraded sequentially. The associated problems in fulfilling the time-window requirement and the inadequacy of this criterion for the ready biodegradability assessment of surfactants are illustrated and discussed.

The 'two-phase closed bottle test'--a suitable method for the determination of 'ready biodegradability' of poorly soluble compounds

The Two-Phase Closed Bottle test (BODIS test) is a cost-effective supplement of the existing OECD tests for ready biodegradability (OECD 301) due to its entire compatibility with them and its particular suitability for testing poorly soluble compounds. The comparison of a number of test data from this and other ready biodegradability tests showed that the BODIS test has a similar stringency in terms of the attainment of the pass level and the time window criterion as well. A significant influence of the strength of the bacterial inoculum on the test results was not observed.

Comparative evaluation of anaerobic biodegradability of hydrocarbons and fatty derivatives currently used as drilling fluids

The examination of a number of potential and currently used carrier fluids for invert emulsion drilling fluids in the ECETOC screening test revealed clear differences with respect to their easy anaerobic biodegradability. Fatty acid- and alcohol-based ester oils exhibited excellent anaerobic degradation to the gaseous final end products of the methanogenic degradation pathway, methane and carbon dioxide. Mineral oils, dialkyl ethers, alpha-olefins, polyalphaolefins, linear alkylbenzenes and an acetal-derivative were not or only slowly degraded. Although the poor degradation results obtained in the stringent ECETOC screening test may not be regarded as final proof of anaerobic recalcitrance, nevertheless, these results were found to be in line with the present understanding of the structural requirements for anaerobic biodegradability of chemicals. The validity of the conclusions drawn is corroborated by published results on the anaerobic biodegradation behaviour of ester oils, mineral oils and alkylbenzenes in marine sediments.

Metabolites and biodegradation pathways of fatty alcohol ethoxylates in microbial biocenoses of sewage treatment plants

The biodegradation of fatty alcohol polyglycol ethers was studied by analyzing the 14C-labeled intermediates isolated from the effluent of a model continuous-flow sewage treatment plant after dosage of either alkyl- or heptaglycol-labeled stearyl alcohol ethoxylate (SA-7EO). In each case, uncharged and carboxylated (mainly dicarboxylated) polyethylene glycols constituted the most prominent metabolites. The results indicate that there is a faster degradation of the alkyl than the polyethylene glycol moiety and that there are two distinct primary degradation mechanisms acting simultaneously in microbial biocenoses: intramolecular scission of the surfactant as well as omega- and beta-oxidation of the alkyl chain. Characterization of the bulk of 14C-labeled metabolites as a homologous series of neutral and acidic polyglycol units and identification of several C2-fragments accounted for the depolymerization of the hydrophilic part of the surfactant by stepwise cleavage of ether-bound EO units; from additional degradation studies employing either neutral or carboxylated 14C-labeled polyethylene glycols as model metabolites, it was concluded that hydrolytic as well as oxidative cleavage of C2-units is involved. Most of the identified low-molecular-weight 14C-labeled acids suggest an ultimate degradation of EO monomers by the oxidative dicarbonic acid cycle or the glycerate pathway or both. In addition, the finding of considerable amounts of oxalic and formic acids allow consideration of an additional mineralization route via glyoxylic, oxalic, and formic acids. The simultaneous action of different degradation mechanisms indicates the involvement of several distinct bacterial groups in the biodegradation of fatty alcohol ethoxylates under environmental conditions.

Structure and biosynthesis of teichoic acids in the cell walls of Staphylococcus xylosus DSM 20266

The simultaneous occurrence of a N-acetylglucosaminyl poly(ribitolphosphate) (beta-GlcNAc) and a N-acetylglucosaminyl poly(glycerolphosphate) (alpha-GlcNAc) in the cell walls of Staphylococcus xylosus DSM 20266 was demonstrated by different experimental lines: (1) Fractionation of extracted cell wall teichoic acid on DEAE-cellulose, (2) investigation of the composition of cell walls in the growth cycle, (3) in vitro biosynthesis using crude membranes as the source of enzyme. The polymerization of these polymers starts from CDP-ribitol and CDP-glycerol, respectively. In the presence of UDP-N-acetylglucosamine both polymers are substituted with N-acetylglucosamine at a level and with the identical anomeric configuration found in the native cell wall teichoic acids. The in vitro biosynthesis of poly(glycerolphosphate) was unique in that it was highly stimulated by UDP-N-acetylglucosamine and to a lower extent by other UDP-activated sugars. Kinetic studies have provided evidence that this stimulation is due to an increase of Vmax while Km is unchanged. Competition experiments have indicated that poly(ribitolphosphate) and poly(glycerolphosphate) were synthesized in the in vitro system in a close spatial relationship.

Halococcus morrhuae: a sulfated heteropolysaccharide as the structural component of the bacterial cell wall

The qualitative and quantitative composition of purifed cell wall of Halococcus morrhuae CCM 859 was determined. Glucose, mannose, galactose; glucuronic and galacturonic acids; glucosamine, galactosamine, gulosaminuronic acid; acetate, glycine and sulfate are found as major constituents. The amino sugars are N-acetylated. It was not possible to fractionate the cell wall in chemically different polymers. Evidence is presented that the major cell wall polymer of this strain is a complex heterolgycan which seems, like the peptidoglycan of most bacteria, to be responsible for the rigidity and stability of the cell wall. In addition it could be proved that this heteroglycan is sulfated and therefore differs considerably from previously described bacterial cell wall polymers.