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Biomedical subjects

L Bianciardi

Publications and source records attributed to L Bianciardi.

9 recordsLinked to original sources
PubMed1990

[Dosimetry problems of radiotherapy with electron fields of small dimension or partially shielded].

In radiotherapy in many clinical cases it is necessary to employ electron beams of small dimensions and/or shielded in order to have shaped fields. It is well known that percentage depth dose and output depend on the energy, on the field dimensions and on the collimation system. In order to evaluate separately the influence of these factors measurements were performed with electron beams of nominal energy from 6 to 14 MeV, of a linear accelerator Philips SL/75. Measurements were performed in standard dimension phantoms and in a small perspex phantom, 3 cm diameter. The values obtained in this small phantom were compared with the ones obtained for the same diameter collimator in order to have information on effect of missing lateral scatter equilibrium. Other measurements for an applicator, open and partially shielded, were performed. The results of these measurements are shown in graphics. Data show that the percentage depth dose ionization curves at fixed energy depend on the collimator linear dimension in particular, when these dimensions are smaller than the range of secondary electrons. However it is evident the difficulty to find a correlation between linear field dimensions and the percentage depth ionization curves. In the clinical practice it is important to take into account this difficulty when employing small or irregular electron fields.

Electrons↗
PubMed1990

[Intraoperative radiotherapy with electrons (IORT). Dosimetry problems, first experience].

In this paper, preliminary results on the IORT dosimetry performed on the two radiotherapy centers, "Regina Elena National Cancer Institute" and "S. Cuore Catholic University", are presented. The absolute dosimetry has been performed with ion chambers (ENEA chamber and Markus flat chamber) using a water phantom. The relative measurements have been performed with solid state diodes and radiographic films, calibrated on absolute dosimetry system.

Combined Modality Therapy↗
PubMed1977

Field separation in radiation therapy with opposing fields.

Dose distribution at the junction of two pairs of opposing fields with 60Co radiation was investigated. In order to obtain a uniform dose distribution, the field separation at the depth of interest was found to be the most important parameter. Values of this parameter to be used in every specific situation are reported. A simple formula is derived, which should be of practical help to the radiotherapist. This formula enables one to compute the field separation at the skin level in order to obtain the best dose distribution in the junction area at the tumor depth.

Cobalt Radioisotopes↗
PubMedDate not supplied

A study of quality of bremsstrahlung spectra reconstructed from transmission measurements.

A numerical method for the reconstruction of bremsstrahlung spectra has been applied to the analysis of simulated data. The method is found to be reliable in reconstructing x-ray spectra of maximum energy up to 10 MeV. Measurements of aluminum transmission data carried out for five linear accelerators have also been analyzed by this method to determine the fractional energy fluence. The values of the Spencer-Attix water/air stopping power ratio, SS.A. w,air, reported as a function of the ratios TPR20 10, are in good agreement with computed results. Quality index values were correlated to mean incident energies of x-ray beams used in radiotherapy. The experimental setup has also provided information regarding the softening effect on the off-axis beam, which can be used in clinical computer dosimetry to correct conventional zero field size tissue maximum ratio.

Image Processing, Computer-Assisted↗
PubMedDate not supplied

Stereotactic irradiation therapy. Physical and dosimetric problems.

In stereotactic irradiation by external beams there are many problems involved with dosimetry of small fields, three-dimensional representation of dose distribution, radiobiological involvement of tissue response to total dose and fractionation. Dosimetric problems arise by critical dimension of dosimetric chambers and by difficulties of films calibration. The amount of data required for a correct three-dimensional simulation of isodose curves, tumor and anatomical structures require a very speed computer system, sophisticated computer graphic techniques and calculation algorithm. By use the linear quadratic model of cell survival, maps of combined dose and biological effect (isoeffect curves) are also obtained.

Brain Neoplasms↗
PubMedDate not supplied

Device-specific risk of needlestick injury in Italian health care workers.

OBJECTIVES: To identify the types of medical devices causing needlestick injuries among Italian health care workers, to document the device-specific injury rates and time trends for different hollow-bore needles, and to compare injury rates from these devices with those reported in the United States. DESIGN: Longitudinal survey. SETTINGS: Twelve Italian acute care public hospitals. METHODS: Data were obtained from a multihospital surveillance database on the number of total injuries reported in each device category. Hospitals provided the corresponding number of devices used annually for each needle type. MAIN OUTCOME MEASURE: Number of needlestick injuries by type of hollow-bore needle per 100,000 devices used per year. RESULTS: A total of 2524 injuries from hollow-bore needles were reported. Disposable syringes/hypodermic needles accounted for 59.3% of injuries, followed by winged steel needles (33.1%), intravenous catheter stylets (5.4%), and vacuum-tube phlebotomy needles (2.2%). Intravenous catheter stylets had the highest needlestick injury rate (15.7/100,000 devices used), and disposable syringes had the lowest needlestick injury rate (3.8/100,000). In contrast to the other devices, the injury rate from winged steel needles increased from 6.2 per 100,000 in 1990 to 13.9 per 100,000 in 1992. CONCLUSIONS: The device-specific needlestick injury rates in Italy are similar to those reported in the United States, suggesting similar exposure experience in two countries. However, in contrast to the United States, needleless intravenous access is standard practice in Italy and thus eliminates one potential risk to Italian health workers. Implementation of safer equipment, such as shielded or retracting needles, and continuing training programs are needed to further reduce the hazards that health care workers face.

Accidents, Occupational↗