Clinical implementation of dynamic multileaf collimation for compensated bladder treatments.

BACKGROUND AND PURPOSE: To describe the clinical implementation of dynamic multileaf collimation (DMLC). Custom compensated four-field treatments of carcinoma of the bladder have been used as a simple test site for the introduction of intensity modulated radiotherapy.MATERIALS AND METHODS: Compensating intensity modulations are calculated from computed tomography (CT) data, accounting for scattered, as well as primary radiation. Modulations are converted to multileaf collimator (MLC) leaf and jaw settings for dynamic delivery on a linear accelerator. A full dose calculation is carried out, accounting for dynamic leaf and jaw motion and transmission through these components. Before treatment, a test run of the delivery is performed and an absolute dose measurement made in a water or solid water phantom. Treatments are verified by in vivo diode measurements and real-time electronic portal imaging. RESULTS: Seven patients have been treated using DMLC. The technique improves dose homogeneity within the target volume, reducing high dose areas and compensating for loss of scatter at the beam edge. A typical total treatment time is 20 min. CONCLUSIONS: Compensated bladder treatments have proven an effective test site for DMLC in an extremely busy clinic.

Gas-phase photocatalytic oxidation of dichlorobutenes

Gas-phase photocatalysis of 1,4-dichlorobut-2-enes and 3,4-dichlorobut-1-ene (DCB) has been studied using TiO2 and 3%WO3/TiO2 supported on SiO2. DCB was found to oxidize efficiently over these catalysts; however, only low rates of CO2 formation were observed. With these chlorinated hydrocarbons, the catalysts were found to deactivate over time, probably via the formation of aldol condensation products of chloroacetaldehyde, which is the predominant intermediate observed. The variation in rate and selectivity of the oxidation reactions with O-2 concentration is reported and a mechanism is proposed. Using isotope ratio mass spectrometry, the initial step for the DCB removal has been shown not to be a carbon bond cleavage but is likely to be hydroxyl radical addition to the carbon-carbon double bond.

Use of a batch rotating photocatalytic contactor for the degradation of organic pollutants in wastewater

Aqueous solutions of a chlorinated VOC, 3,4-dichlorobut-1-ene, as well as other pollutants, may be mineralised to carbon dioxide, water and hydrochloric acid using a sealed rotating photocatalytic reactor. The effect of pH, dissolved oxygen concentration, light intensity, pollutant concentration and rotation speed on the degradation rate have been investigated as well as competition kinetics with methanol. This reactor may be optimised to minimise competition effects in mixed solutions. (C) 2001 Elsevier Science B.V. All rights reserved.

Malignant pleural mesothelioma: current treatments and emerging drugs

Background: Malignant pleural mesothelioma (MPM) is an uncommon disease whose incidence is increasing worldwide over the past 30 years. Surgical resection and radiotherapy represent the standard treatment in patient with resectable MPM. Chemotherapy is also necessary to reduce incidence of distant metastases, but the optimal setting of treatment (neoadjuvant, adjuvant and intrapleural) is not clarified. For the patients with unresectable MPM, the combination cisplatin and pemetrexed or ralitrexed is the standard treatment as supported by a Phase III study. Better understanding of molecular pathways involved in MPM has enabled inclusion of new drugs targeted against pathways responsible for proliferation, cell survival and angiogenesis. Objective: This review discusses the current treatment option, the specific signal pathways activated in MPM and the novel agents under evaluation in clinical trials. Methods: We use for this article abstracts, papers, oral presentations from ASCO and the website http://www.clinical-trials.gov. Results/conclusion: This review summarizes the activity of chemotherapy and of new agents under evaluation in clinical trials. The better understanding of molecular pathways activated in MPM will hopefully provide new therapeutic options for these patients in the future.

Indirect comparisons of treatments based on systematic reviews of randomised controlled trials

Randomised controlled trials are the most effective way to differentiate between the effects of competing interventions. However, head-to-head studies are unlikely to have been conducted for all competing interventions.