Introducing a new ICRU report: Prescribing, recording and reporting electron beam therapy

The ICRU published several Reports about volumes and doses specifications for radiotherapy, such as the Report 29 (1978), devoted to photon and electron beam therapy. This report 29 becoming absolete, a new Report was published in 1993 for external photon beam radiotherapy, the Report 50, recommending new definitions and more accurate specifications. With electran beams specific problems are raised, and the ICRU considered suitable to prepare a special Report for them, to be published in the near future.The main features of the present draft are as follows:1.Volumes specifications in agreement with the ICRU Report 50,•Volumes to be determined before treatment planning: gross tumour volume (GTV), c1inical target volume (CTV), organs at risk volumes (OR).•Volume to be determined during treatment planning: Planning target volume (PTV).•Volumes resulting fram the treatment plan chosen: treatment volume (TV), irradiated volume (IV).In the future Report on electron beams, an additional volume is defined, the internal target volume (ITV) geometrical concept representing the volume en-compassing the c1inical target volume, taking into consideration margins due to the variations of the clinical target volume in position, shape an size. A similar concept has been extended to organs at risk, the planning organ at risk volume.2.Dose specificationThe general statements for photon beams apply:•dose at a reference point (ICRU point) situated at or near the center of the planning target volume and, when possible, near or on the central axis of the electron beam at the depth of the peak dose.•Minimal and maximal doses in the planning target volume•Dose delivered to the organs at risk•Additional information is recommended, when possible (e.g. DVH).With electron beams, the dose homogeneity expected within the PTV (± 5 to ± 10 %) requires an adaptation of the terapeutic range concept, such that the value of the isodose surface encompassing the PTV be situated between 85 % and 95 % of the reference dose. The peak absorbed dose on the beam axis should always been specified, even if it is different fram the reference dose.At last, as in Report 50, three levels of dose evaluation for reporting are considered, depending on the aim of the treatment and the data available

Influence of hygrothermal aging on the gas and water transport properties of Nafion (R) membranes

International audienceThe membrane durability is a critical issue for proton exchange membrane fuel cell development. Nafion (R) is usually considered as a reference membrane due to its high chemical stability. However, a condensation mechanism of the sullonic groups to fOrM anhydrides was evidenced when Nafioe (R) membranes were stored at 80 degrees C under humid atmospheres. In the present work, Nafion (R) 112 membranes and chemically stabilized Nafion (R) I' NRE212C5 membranes commercialized to replace Nafion (R)) 112 were studied under hygrothermal aging performed at 80 degrees C for two relative humidity conditions: 80% and 95%. The impact of the aging conditions was investigated on membrane water and gas transport properties over the whole range of water activity. For both membrane types, a progressive decrease of the water uptakes was observed as a function of aging time. The hygrothermal aging process was faster for Nafioe 112 membranes than for the chemically stabilized Nalioe' membranes, It became slower as the relative humidity of the aging atmosphere decreased from 95% to 80%. A water transport mechanism based on sorption and permeation data was proposed for the aged membranes taking account of the water/polymer interactions and of the progressive crosslinking of the Nation" hydrophilic phase. The gas transport properties were studied for H-2, O-2 and CO2 at different water activities. The decrease of the gas permeability coefficients observed for the aged membranes in comparison with the neat membranes confirmed the presence of gas diffusion pathways within the Nafion (R) hydrophilic phase. The role of these diffusion paths was discussed as a function of the membrane hydration state, as a function of the aging conditions and of the polarity and size of the diffusing gas molecules

Radiodiagnostic chez la femme enceinte

Nous rapportons ici une série de 153 grossesses irradiées de façon accidentelle en début de gestation, toutes analysées selon le même mode dosimétrique. Aucune indication d’interruption thérapeutique de grossesse n’a été posée, aucune de nos consultantes n’ayant reçu plus de 100 mGy. Les taux de malformation et d'avortement spontané sont identiques à ceux observés dans le reste de la population

Retrosigmoid approach for resection of petrous apex meningioma

We present the case of a 50-year-old female with a 1-year history of right-side facial numbness, as well as an electric shock-like sensation on the right-side of the face and tongue. She was previously diagnosed with vertigo and trigeminal neuralgia. MRI was obtained showing a large right cerebellopontine angle mass. A retrosigmoid approach was performed and total removal was achieved after dissection of tumor from brainstem and cranial nerves IV, V, VI, VII and VIII. Pathology confirmed the diagnosis of a meningioma (WHO Grade I). The patient was discharged neurologically intact on the third postoperative day free of complications. The video can be found here: http://youtu.be/-tR0FtMiUDg

IMRT credentialing for prospective trials using institutional virtual phantoms: results of a joint European Organization for the Research and Treatment of Cancer and Radiological Physics Center project.

BACKGROUND AND PURPOSE Intensity-modulated radiotherapy (IMRT) credentialing for a EORTC study was performed using an anthropomorphic head phantom from the Radiological Physics Center (RPC; RPC(PH)). Institutions were retrospectively requested to irradiate their institutional phantom (INST(PH)) using the same treatment plan in the framework of a Virtual Phantom Project (VPP) for IMRT credentialing. MATERIALS AND METHODS CT data set of the institutional phantom and measured 2D dose matrices were requested from centers and sent to a dedicated secure EORTC uploader. Data from the RPC(PH) and INST(PH) were thereafter centrally analyzed and inter-compared by the QA team using commercially available software (RIT; ver.5.2; Colorado Springs, USA). RESULTS Eighteen institutions participated to the VPP. The measurements of 6 (33%) institutions could not be analyzed centrally. All other centers passed both the VPP and the RPC ±7%/4 mm credentialing criteria. At the 5%/5 mm gamma criteria (90% of pixels passing), 11(92%) as compared to 12 (100%) centers pass the credentialing process with RPC(PH) and INST(PH) (p = 0.29), respectively. The corresponding pass rate for the 3%/3 mm gamma criteria (90% of pixels passing) was 2 (17%) and 9 (75%; p = 0.01), respectively. CONCLUSIONS IMRT dosimetry gamma evaluations in a single plane for a H&N prospective trial using the INST(PH) measurements showed agreement at the gamma index criteria of ±5%/5 mm (90% of pixels passing) for a small number of VPP measurements. Using more stringent, criteria, the RPC(PH) and INST(PH) comparison showed disagreement. More data is warranted and urgently required within the framework of prospective studies