Attenuation assessment of medical protective eyewear: the AVEN experience.

The goal of this paper is to test the attenuation capability of seven models of protective eyewear used in routine clinical practice. Scattered radiation from a standard patient was simulated by using a water tank located over the treatment couch of a GE Innova 3100 x-ray angiography system. Seven protective eyewear models were tested using an anthropomorphic phantom mimicking the first operator. At each test, 4 thermoluminiscent dosimeters were placed on the phantom (respectively in front of the protective eyewear, under the eyewear, on the left earpiece and at chest level) in order to have an eyewear-independent reference. A test session without glasses was also acquired. Each model was tested with standard posterior-anterior (PA) projections and the two most common protective eyewear were tested using LAO90° and LAO45°CRA30° projections. A worst-case scenario was created to be sure of having an upper limit for the assessment of eyewear attenuation in routine clinical practice. In PA projections, the absolute attenuation value ranged between 71% and 81%, while relative attenuation between dose measured at eye lens and that measured at eyewear earpiece ranged from 67% to 85%. The slightly wider range was probably due to scatter radiation variability; anyway, differences are still included in the variable uncertainty of experimental measurements. It is worth noting that #3 eyewear model (the one without lateral protection) allows an attenuation similar to that of #5 eyewear model (with 0.5 mm lead lateral protection) in LAO90° and LAO45°CRA30° projections. Despite the experimental limitations, a description of the radiation properties of protective eyewear concerning radiation attenuation can be useful to rely on protection devices which can be used in routine clinical practice.

Porphyrin conjugated SiC/SiOx nanowires for X-ray-excited photodynamic therapy.

The development of innovative nanosystems opens new perspectives for multidisciplinary applications at the frontier between materials science and nanomedicine. Here we present a novel hybrid nanosystem based on cytocompatible inorganic SiC/SiOx core/shell nanowires conjugated via click-chemistry procedures with an organic photosensitizer, a tetracarboxyphenyl porphyrin derivative. We show that this nanosystem is an efficient source of singlet oxygen for cell oxidative stress when irradiated with 6 MV X-Rays at low doses (0.4-2 Gy). The in-vitro clonogenic survival assay on lung adenocarcinoma cells shows that 12 days after irradiation at a dose of 2 Gy, the cell population is reduced by about 75% with respect to control cells. These results demonstrate that our approach is very efficient to enhance radiation therapy effects for cancer treatments.

Thallium 201 for detection of viable myocardium: comparison of different reinjection protocols.

BACKGROUND: The finding fo false fixed 201Tl defects by the conventional stress-redistribution protocol is a well-known phenomenon. The aim of this study was to compare two different 201Tl reinjection protocols to identify viable myocardium in the same group of patients. METHODS AND RESULTS: Twenty-seven patients with ischemic heart disease and at least one persistent defect on 201Tl uptake redistribution images 3 hours after stress were investigated. In the same-day protocol (R1) patients were reinjected with 1 mCi 201Tl immediately after redistribution images, with imaging starting 15 minutes later; in the different-day protocol the patients were reinjected with 2 mCi 48 to 96 hours later. Two sets of images were obtained, 30 (R2) and 180 (R3) minutes after reinjection. The comparison of redistribution and reinjection versus stress images showed a significant (p < 0.01) frequency distribution. The uptake of 201Tl of the 111 irreversible segments at redistribution was enhanced in 35.1% with R1, 43.2% with R2, and 49.5% with R3. The agreement among the three procedures in classifying the segmental defects was high between R2 and R3 (r = 0.81) and lower between the same- and different-day protocols. Of the 19 patients with a dominant scar pattern demonstrated by the conventional stress-redistribution study, 37%, 47%, and 53% were judged mainly ischemic after R1, R2, and R3, respectively. All but three of the 55 segments-showing an increased 201Tl uptake by R3 had an echocardiographic score of 2 or greater. CONCLUSION: The best technique to differentiate scarred from viable myocardium seems to be the reinjection of a second dose of 201Tl on a different day followed by imaging 3 hours later.