New simple and low-cost methods for periodic checks of Cyclone® Plus Storage Phosphor System

The recent large use of the Cyclone® Plus Storage Phosphor System, especially in European countries, as imaging system for quantification of radiochemical purity of radiopharmaceuticals raised the problem of setting the periodic controls as required by European Legislation. We described simple, low-cost methods for Cyclone® Plus quality controls, which can be useful to evaluate the performance measurement of this imaging system

In vivo dosimetry and shielding disk alignment verification by EBT3 GAFCHROMIC film in breast IOERT treatment

Intraoperative electron radiation therapy (IOERT) cannot usually benefit, as conventional external radiotherapy, from software systems of treatment planning based on computed tomography and from common dose verify procedures. For this reason, in vivo film dosimetry (IVFD) proves to be an effective methodology to evaluate the actual radiation dose delivered to the target. A practical method for IVFD during breast IOERT was carried out to improve information on the dose actually delivered to the tumor target and on the alignment of the shielding disk with respect to the electron beam. Two EBT3 GAFCHROMIC films have been positioned on the two sides of the shielding disk in order to obtain the dose maps at the target and beyond the disk. Moreover the postprocessing analysis of the dose distribution measured on the films provides a quantitative estimate of the misalignment between the collimator and the disk. EBT3 radiochromic films have been demonstrated to be suitable dosimeters for IVD due to their linear dose-optical density response in a narrow range around the prescribed dose, as well as their capability to be fixed to the shielding disk without giving any distortion in the dose distribution. Off-line analysis of the radiochromic film allowed absolute dose measurements and this is indeed a very important verification of the correct exposure to the target organ, as well as an estimate of the dose to the healthy tissue underlying the shielding. These dose maps allow surgeons and radiation oncologists to take advantage of qualitative and quantitative feedback for setting more accurate treatment strategies and further optimized procedures. The proper alignment using elastic bands has improved the absolute dose accuracy and the collimator disk alignment by more than 50%

HR3DHG version 1: modeling the spatiotemporal dynamics of mercury in the Augusta Bay (southern Italy)

yyThe biogeochemical dynamics of Hg, and specifically of its three species Hg-0, Hg-II, and MeHg (elemental, inorganic, and organic, respectively), in the marine coastal area of Augusta Bay (southern Italy) have been explored by the high-resolution 3D Hg (HR3DHG) model, namely an advection-diffusion-reaction model for dissolved mercury in the seawater compartment coupled with a diffusion-reaction model for dissolved mercury in the pore water of sediments in which the desorption process for the sediment total mercury is taken into account. The spatiotemporal variability of the mercury concentration in both seawater ([Hg-D]) and the first layers of bottom sediments ([Hg-D(sed)] and [Hg-T(sed)]), as well as the Hg fluxes at the boundaries of the 3D model domain, have been theoretically reproduced, showing acceptable agreement with the experimental data collected in multiple field observations during six different oceanographic cruises. Also, the spatiotemporal dynamics of the total mercury concentration in seawater have been obtained by using both model results and field observations. The mass balance of the total Hg species in seawater has been calculated for the Augusta Harbour, improving previous estimations. The HR3DHG model could be used as an effective tool to predict the spatiotemporal distributions of dissolved and total mercury concentrations, while contributing to better assessing hazards for the environment and therefore for human health in highly polluted areas

Evaluation of localized region-based segmentation algorithms for CT-based delineation of organs at risk in radiotherapy

Background and purpose: In radiation therapy, defining the precise borders of cancerous tissues and adjacent normal organs has a significant effect on the therapy outcome. Deformable models offer a unique and robust approach to medical image segmentation. The objective of this study was to investigate the reliability of segmenting organs-at-risk (OARs) using three well-known local region-based level-set techniques. Methods and materials: A total of 1340 non-enhanced and enhanced planning computed tomography (CT) slices of eight OARs (the bladder, rectum, kidney, clavicle, humeral head, femoral head, spinal cord, and lung) were segmented by using local region-based active contour, local Chan-Vese, and local Gaussian distribution models. Quantitative metrics, namely Hausdorff Distance (HD), Mean Absolute Distance (MAD), Dice coefficient (DC), Percentage Volume Difference (PVD) and Absolute Volumetric Difference (AVD), were adopted to measure the correspondence between detected contours and the manual references drawn by experts. Results: The results showed the feasibility of using local region-based active contour methods for defining six of the OARs (the bladder, kidney, clavicle, humeral head, spinal cord, and lung) when adequate intensity information is available. While the most accurate results were achieved for lung (DC = 0.94) and humeral head (DC = 0.92), a poor level of agreement (DC < 0.7) was obtained for both rectum and femur. Conclusion: Incorporating local statistical information in level set methods yields to satisfactory results of OARs delineation when adequate intensity information exists between the organs. However, the complexity of adjacent organs and the lack of distinct boundaries would result in a considerable segmentation error. Keywords: Organs at risk segmentation, Local region based, Level set, Radiotherapy treatment plannin

A multicenter dosimetry study to evaluate the imaging dose from Elekta XVI and Varian OBI kV-CBCT systems to cardiovascular implantable electronic devices (CIEDs)

The increasing use of daily CBCT in radiotherapy has raised concerns about the additional dose delivered to the patient, and it can also become a concern issue for those patients with cardiovascular implantable electronic devices (CIEDs) (Pacemaker [PM] and Implantable Cardioverter Defibrillator [ICD]). Although guidelines highly recommend that the cumulative dose received by CIEDs should be kept as low as possible, and a safe threshold based on patient risk classification needs to be respected, this additional imaging dose is not usually considered. Four centers with different dosimetry systems and different CBCT imaging protocols participated in this multicenter study to investigate the imaging dose to the CIEDs from Elekta XVI and Varian OBI kV-CBCT systems. It was found that although imaging doses received by CIEDs outside the CBCT field are negligible, special attention should be paid to this value when CIEDs are inside the field because the daily use of CBCT can sometimes contribute considerably to the total dose received by a CIED