Total VOC reactivity in the planetary boundary layer: 2. A new indicator for determining the sensitivity of the ozone production to VOC and NO

A new indicator is proposed for determining if tropospheric ozone production in a specifiacr eai s limitedb yV OC or NOx.T he indicato1r 9= r•ø•C/•oød•Xes cribeths e ratio of the lifetimes of OH against the losses by reacting with VOC and NOx. Whereas •oøx• c anb e obtainebdy c onventionmale asurementthse, n ewp umpa ndp robeO H approach which is described in part one of this publication makes it now possible to obtain also ß_ov •o c ßI ndicator values above a thresholdv alue of 0.2 __+50 % are representativeo f NOx-saturatedc onditionsw here an increaseo f NOx emissionsc auses lower ozone production.F or valuesb elow 0.01 the ozone productioni s very insensitivet o changeso f VOC emissionsT. he robustnesso f this indicator againsts everalp arameters sucha s temperature,h umidity,p hotolysisa, nd initial ozone concentrationsis tested in a box model and comparedt o the robustnesso f other earlier proposedi ndicators.I n contrast to earlier proposed indicators, this new one is not based on photochemically producedl ong-liveds peciesb ut describest he instantaneousr egime of an air parcel. Three-dimensionasl imulations howst hat this indicator is quite successfuiln estimatingt he impact of increasedo r reducede missionso n the ozone concentrationsfo r each location in the modeling area. This will make it a very helpful tool for developing ozone abatement strategies

Total VOC reactivity in the planetary boundary layer: 1. Estimation by a pump and probe OH experiment

The reactivityo f hydroxyrl adical (OH) with total volatile organicc ompounds (VOC), Z kvoc[VOC ], is directly obtained in the planetary boundary layer (PBL). The method is basedo n a perturbationt echniquew here high initial OH concentrationsa re createdb yf lashp hotolysoisf ozonea nds ubsequerneta ctiono f O(•D) withH 20. Laserinduced fluorescence is used to measure the residual OH concentration at different time delays after the perturbation (<100 ms) and obtain a direct estimate of the OH lifetime rOH for different atmospheric conditions. For specific experimental conditions the transportb y the wind may be neglected,a nd the chemicalp rocessesg overningt he OH decaym ay be expressedb y a detailed box model. With a simple chemicale quation derived in this paper using roll and complementarym easurementso f CO, 03, and NOx, an in situ estimate of Z kvoc[VOC ] in the PBL is retrieved with an uncertainty of less than 20% in comparisont o the detailed box model calculationsT. his analysisi s applied to laboratory measurementsw ith three syntheticN Ox/VOC/O 3 gas mixtures,a nd the retrieved OH lifetimes and total VOC reactivitya re discusseda gainstm odel predictions

Physical considerations on discrepancies in target volume delineation.

BACKGROUND AND PURPOSE: To compare the delineations and interpretations of target volumes by physicians in different radio-oncology centers. MATERIALS AND METHODS: Eleven Swiss radio-oncology centers delineated volumes according to ICRU 50 recommendations for one prostate and one head and neck case. In order to evaluate the consistency of the volume delineations, the following parameters were determined: 1) the target volumes (GTV, CTV and manually expanded PTV) and their extensions in the three main axes and 2) the correlation of the volume delineated by each pair of centers using the ratio of the intersection to the union (called proximity index). RESULTS: The delineated prostate volume was 105+/-55cm(3) for the CTV and 218+/-44cm(3) for the PTV. The delineated head and neck volume was 46+/-15cm(3) for the GTV, 327+/-154cm(3) for the CTV and 528+/-106cm(3) for the PTV. The mean proximity index for the prostate case was 0.50+/-0.13 for the CTV and 0.57+/-0.11 for the PTV. The proximity index for the head and neck case was 0.45+/-0.09 for the GTV, 0.42+/-0.13 for the CTV and 0.59+/-0.06 for the PTV. CONCLUSIONS: Large discrepancies between all the delineated target volumes were observed. There was an inverse relationship between the CTV volume and the margin between CTV and PTV, leading to less discrepancies in the PTV than is the CTV delineations. There was more spread in the sagittal and frontal planes due to CT pixel anisotropy, which suggests that radiation oncologists should delineate the target volumes not only in the transverse plane, but also in the sagittal and frontal planes to improve the delineation by allowing a consistency check

Total VOC reactivity in the planetary boundary layer 1. Estimation by a pump and probe OH experiment

OH- radical reactivity with total volatile org. compds. (VOC), SkVOC[VOC], is directly obtained in the planetary boundary layer (PBL). A method is based on a perturbation technique where high initial OH- concns. are created by flash photolysis of O3 and subsequent reaction of O(1D) with H2O. Laser-induced fluorescence measures residual OH- concn. at different time delays after the perturbation (<100 ms) to obtain a direct est. of OH- lifetime (tOH) under different atm. conditions. For specific exptl. conditions, transport by wind may be neglected, and chem. processes governing OH- decay may be expressed using a detailed box model. With a simple chem. equation derived using tOH and complementary measurements of CO, O3, and NOx, an in-situ est. of SkVOC[VOC] in the PBL is retrieved with an uncertainty <20% vs. detailed box model calcns. This anal. was applied to lab. measurements with 3 synthetic NOx/VOC/O3 gas mixts.; retrieved OH- lifetimes and total VOC reactivity are discussed against model predictions

Ozone LIDAR as an analytical tool in effective air pollution management. The Geneva 96 campaign

The LIDAR principle for air quality and meteorol. measurements is presented, followed by different examples of vertical O3 profiles and time series obtained with a new optical layout of the EPFL-LPAS DIAL system using dual telescope detection. These data were obtained during the summer 96 field campaign in the Geneva area. Results are compared with the meso-scale Eulerian model calcns. The results provide new insight into air pollution dynamics in the Geneva area and calcns. are under way, using the model adjusted by the measurements, to optimize air pollution abatement strategies under certain atm. conditions in this part of Switzerland

A treatment planning comparison of contemporary photon-based radiation techniques for breast cancer

Background and purpose: Adjuvant radiation therapy (RT) of the whole breast (WB) is still the standard treatment for early breast cancer. A variety of radiation techniques is currently available according to different delivery strategies. This study aims to provide a comparison of six treatment planning strategies commonly adopted for breast-conserving adjuvant RT and to use the Pareto concept in an attempt to assess the degree of plan optimization. Materials and methods: Two groups of six left- and five right-sided cases with different dose prescriptions were involved (22 patients in total). Field-in-Field (FiF), two and four Fields static-IMRT (sIMRT-2f and sIMRT-4f), Volumetric-Modulated-Arc-Therapy (VMAT), Helical Tomotherapy (HT) and Static-Angles Tomotherapy (TomoDirect™ – TD) were planned. Dose volume constraints were taken from the RTOG protocol 1005. Pareto fronts were built for a selected case to evaluate the reliability of the plan optimization process. Results: The best target dose coverage was observed for TD able to improve significantly (p < 0.01) the V95% in a range varying from 1.2% to 7.5% compared to other techniques. The V105% was significantly reduced up to 2% for HT (p < 0.05) although FiF and VMAT produced similar values. For the ipsilateral lung, V5Gy, V10Gy and Dmean were significantly lower than all other techniques (p < 0.02) for TD while the lowest value of V20Gy was observed for HT. The maximum dose to contralateral breast was significantly lowest for TD (p < 0.02) and for FiF (p < 0.05). Minor differences were observed for the heart in left-sided patients. Plans for all tested techniques were found to lie on their respective Pareto fronts. Conclusions: Overall, TD provided significantly better results in terms of target coverage and dose sparing of ipsilateral lung with respect to all other evaluated techniques. It also significantly minimized dose to contralateral breast together with FiF. Pareto front analysis confirmed the reliability of the optimization for a selected case. Keywords: Treatment planning, Whole-breast irradiation, Planning comparison, Pareto fron

Adherence to oral anticancer treatment: focus on quality of execution during continuous schema of treatment

Background and objective: Oral anti-cancer treatments have expanded rapidly over the last years. While taking oral tablets at home ensures a better quality of life, it also exposes patients to the risk of sub-optimal adherence. The objective of this study is to assess how well ambulatory cancer patients execute their prescribed dosing regimen while they are engaged with continuous anti-cancer treatments. Design: This is an on-going longitudinal study. Consecutive patients starting an oral treatment are proposed to enter the study by the oncologist. Then they are referred to the pharmacy, where their oral anticancer treatment is dispensed in a Medication Event Monitoring System (MEMSTM), which records date and time of each opening of the drug container. Electronically compiled dosing history data from the MEMS are summarized and used as feedback during semistructured interviews with the pharmacist, which are dedicated to prevention and management of side effects. Interviews are scheduled before each medical visit. Report of the interview is available to the oncologist via an on-line secured portal. Setting: Seamless care approach between a Multidisciplinary Oncology Center and the Pharmacy of an Ambulatory Care and Community Medicine Department. Main outcome measures: For each patient, the comparison between the electronically compiled dosing history and the prescribed regimen was summarized using a daily binary indicator indicating whether yes or no the patient has taken the medication as prescribed. Results: Study started in March 2008. Among 22 eligible patients, 19 were included (11 men, median age 63 years old) and 3 (14%) refused to participate. 15 patients were prescribed a QD regimen, 3 patients a BID and 1 patient switched from QD to BID during follow-up. Median follow up was 182 days (IQR 72-252). Early discontinuation happened in four patients: side effects (n = 1), psychiatric reasons (n = 1), cancer progression (n = 1) and death (n = 1). On average, the daily number of medications was taken as prescribed in 99% of the follow-up days. Conclusions: Execution of the prescribed dosing regimens was almost perfect during the first 6 months. Maintaining this high degree of regimen execution and persistence over time might however be challenging in this population and need therefore to be confirmed in larger and longer follow-up cohort studies