Residual haemopoietic damage in the mouse after fractionated gamma-irradiation, down to 0.1 Gy per fraction.

Residual damage in haemopoietic progenitor cell populations, spleen and granulocyte-macrophage colony-forming cells (CFU-S and GM-CFC) was detected in mice after 15 daily fractions where the dose per fraction was as low as 0.1 Gy. The injury was dose-dependent and after higher total fractionated doses of 7.5-10 Gy the CFU-S population recovered to about 50% of control between 2 and 12 months after irradiation. Residual damage was also detected in the stroma, in the form of reduced numbers of fibroblastoid colony-forming cells and of CFU-S in ossicles under the kidney capsule. The response to a second course of 15 fractions, given 3 weeks after the end of the first course, was similar and additive to the response to the first course in the short term. However, in the long term, recovery levels were similar after either one or two courses.

The effect of low dose rate on recovery of hemopoietic and stromal progenitor cells in gamma-irradiated mouse bone marrow.

Long-term recovery of mouse hemopoietic stem cells (CFU-S and CFU-S per colony), granulocyte-macrophage precursor cells (GM-CFC), and stromal colony-forming units (CFU-F) after doses up to 12.5 Gy was almost complete by 1 year when the dose rate was reduced to 0.0005 Gy/min compared to incomplete recovery after doses up to only 6.5 Gy given at greater than 0.7 Gy/min. This sparing effect of dose rate on long-term hemopoietic recovery is in contrast to the generally reported lack of dependence on dose rate for acute survival of hemopoietic progenitors after doses up to 5 Gy. The present results are compatible with the hypothesis that good recovery of the stroma should be reflected in the long-term recovery of hemopoiesis.

The monitoring of tap waters in Milano: planning, methods and results.

The radiometric monitoring of tap waters has been carried out, in Northern Italy, since late the 1980s as part of the activities headed by the National Surveillance Network on environmental radioactivity. Measurements were accomplished by gamma spectrometry over large samples of water that were drained in a single place and concentrated by ion exchange resin treatment. More recently a regular, periodical monitoring was started using liquid scintillation measurements. In this manner, gross alpha and beta activities, uranium, (226)Ra and (222)Rn concentrations are determined at present. Nevertheless, a single-point sampling may be not fully representative of the whole Milano aqueduct, significantly extended and fed by a number of wells. As a control, an extended monitoring of the aqueduct was planned and variations of water radioactivity in different Milano areas have been assessed.

[Analysis of the reasons for the rejection of radiographic films in radiodiagnosis]. / Analisi delle cause di scarto di pellicole radiografiche in radiodiagnostica.

After a study of quality control on about 30 radiological equipment and two dark rooms, we are now presenting an analysis of 1806 radiological examinations with 5011 films; the reject is 6.2%, namely 311 films. The analysis of the causes of the reject gives the following results: the more important cause is the error of exposure (52.7% of total reject), followed by geometrical and collimation defects (14.4%) and by the movement of the patient (13.2%). Our results are discussed and compared with other similar data.

[Results of a program of quality control in radiodiagnosis]. / Risultati di un programma di controlli di qualità in radiodiagnostica.

The results of a program of quality control on about 30 tomographic and fluoroscopic radiological equipments in the Radiological Departments of Spedali Civili (Brescia, Italy), are reported; the physical performances of the beams (kVp, emission, linearity and reproducibility, HVL, focal spot size) and the geometrical conditions (alignment and beam size, thickness of cut for tomography, resolution and homogeneity) have been verified. During one month we have also verified the working conditions for two automatic film processing systems. Three commercial quality control equipments have been employed and tested. Our results recommend a periodic control of physical and geometrical performances (particularly kVp, emission and beam alignment) and a daily control of the working conditions for the film processing systems. The three quality control systems have given results each other comparable.

Induction of 8-azaguanine resistant mutants in human cultured cells exposed to 31 MeV protons.

We report results on the induction of 8-azaguanine (8-AG)-resistant mutants in cultured human cells (EUE) exposed to 31 MeV protons. The spontaneous frequency of mutants was 5.6 +/- 0.7 x 10(-6) per viable cell. Gamma rays were taken as reference radiation. Expression times giving the highest frequency of mutants after 31 MeV protons and gamma irradiation were found to be about 10 days for both radiations. The dose-response relationship for mutant induction by protons, as determined at the optimal expression time, was compared to that obtained after gamma rays. The relative biological effectiveness (RBE) is 2.4 +/- 0.5, this value being higher than the RBE value determined for cell survival.

Assessment of drinking water radioactivity content by liquid scintillation counting: set up of high sensitivity and emergency procedures.

In our institute, different procedures have been developed to measure the radioactivity content of drinking water both in normal and in emergency situations, such as those arising from accidental and terrorist events. A single radiometric technique, namely low level liquid scintillation counting (LSC), has been used. In emergency situations a gross activity screening is carried out without any sample treatment by a single and quick liquid scintillation counting. Alpha and beta activities can be measured in more than one hundred samples per day with sensitivities of a few Bq/L. Higher sensitivity gross alpha and beta, uranium and radium measurements can be performed on water samples after specific sample treatments. The sequential method proposed is designed in such a way that the same water sample can be used in all the stages, with slight modifications. This sequential procedure was applied in a survey of the Lombardia district. At first tap waters of the 13 largest towns were examined, then a more detailed monitoring was carried out in the surroundings of Milano and Lodi towns. The high sensitivity method for the determination of uranium isotopes was used to check the presence of depleted uranium in Lake Garda. Reduced equipment requirements and relative readiness of radiochemical procedures make LSC an attractive technique which can also be applied by laboratories lacking specific radiochemistry facilities and experience.

[Optimization of the thoracic radiograph. Experimental and clinical study on the use of various film/screen combinations using rare earths]. / Ottimizzazione del radiogramma toracico. Studio sperimentale e clinico sull'impiego di diverse combinazioni film/schermi alle terre rare.

The optimization of chest radiography is a still unresolved problem, as it must answer to various clinical requirements. Even if sometimes the choice is not difficult, it becomes hard when the best film-screen combination is needed. In order to assess the optimization image quality and exposition, different experimental and clinical conditions have been investigated referring to the various combination of screen, film and tension. The Trimax system has been chosen for our investigations, performed in two different phases: the former on an anthropomorphous chest phantom, the latter on 25 patients affected by lung interstitial diseases, mainly nodular. The results are discussed.