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Biomedical subjects

G Poretti

Publications and source records attributed to G Poretti.

10 recordsLinked to original sources
PubMed1987

Accumulation of anthracotic particles along lymphatics of the human lung: relevance to "hot spot" formation after inhalation of poorly soluble radionuclides.

Large lung sections of humans of advanced adult age revealed a markedly nonuniform retention pattern of dense anthracotic particle aggregates, with an impressive accumulation of this material along pulmonary lymphatics, i.e. the deep (peribronchial), septal (perivenous) and superficial (pleural) networks. Conversely, the alveolar parenchyme contained only occasional, small aggregates of macrophages heavily loaded with carbon, representing little more than 2% of this material in lung tissue. Although translocation kinetics of anthracotic particles cannot readily be compared to those of highly toxic alpha-emitting, poorly soluble radionuclides such as 239PuO2, lymphatic drainage of the latter over the years may also be expected to lead to a concentration of radioactive material along lymph vessels. Since human data on the effects of inhaled 239PuO2 are virtually lacking, the above distribution pattern is apt to help in identifying cells and other tissue components most heavily at risk. Findings are also relevant to the problem of "hot spot" formation in vivo and its possible sequelae. The latter are briefly discussed with regard to both stochastic and non-stochastic effects.

Cell Aggregation↗
PubMed1984

[Comparison between CT and NMR images. Physical aspects].

On the basis of simple physical considerations, parameters influencing the computer tomograph (CT) and nuclear magnetic resonance (NMR) pictures are compared. In the case of the CT, only X-ray tube voltage and radiation intensity (i.e. dose to the patient) can be altered. Changing the X-ray tube voltage alone produces no special diagnostic advantages, unless the method is supplemented, for a specific body region, by separate determination of the "Hounsfield number" in Compton or photoelectric numbers. However, the method is associated with relatively major measurement and evaluation problems. A survey of the principles of the NMR technique is followed by a brief explanation of the so-called "tissue parameters" and "measurement parameters" which influence picture quality in the NMR technique. Despite certain advantages it can scarcely be expected that the NMR technique will replace the CT technique in the next few years: it is very probable, however, that a shift to specific examinations will occur in the case of the latter.

Humans↗
PubMed1984

[Human bone marrow burden in dermatologic radiation].

The exposure to radiation of the entire red bone marrow was determined in three dermatologic X-ray treatment situations by means of a phantom in which the bones were supplied with 55 measuring sites. In each measurement the field was in the area of the left cheek. The parameters of radiation were in measurement 1/2/3: voltage = 50/43/43 kV, filter = 1.0/0.6/0.6 mm Al, field = 12.5/12.5/3.0 cm diameter, focus-skin distance = 30/30/15 cm, tissue half-value thickness = 13.0/7.5/5 mm. Related to a surface dose of 400 rad, the radiation exposure of the red marrow was 1555 mrad in measurement 1, 556 mrad in measurement 2 and 118 mrad in measurement 3. These results are discussed. The exposure to radiation of the red marrow in dermatologic X-ray treatments is not negligible and should not be omitted when evaluating the benefit and risk of dermatologic X-ray treatments.

Bone Marrow↗
PubMed1983

Spontaneous hematologic recovery from bone marrow aplasia after accidental tenfold overdosage with radiophosphorus.

Two patients with polycythemia vera received intravenously an accidental tenfold overdosage of radiophosphorus therapy (60 and 50 mCi 32P, respectively). In both patients, the occurrence of hemorrhagic complications 3 wk after the 32P medication led to detection of the error and referral to our hospital. Upon admission they showed an agranulocytosis, severe thrombocytopenia, and bone marrow aplasia. In both cases, spontaneous recovery of the hematopoiesis was observed from day 40 posttreatment onward. In one patient, a slow but ultimately complete normalization of blood counts and marrow morphology took place, whereas in the other, a mild thrombocytopenia persists. Nearly 5 yr after the accidental overdosage, both patients are clinically well. Symptoms of polycythemia vera have not reappeared up to now. Attempts were made to evaluate the radiation dose absorbed by the bone marrow. In the first patient, the daily 32P excretion was determined from day 22 to day 60, whereas in the other patient a whole body count was performed on day 78 after administration. From these results, an approximate cumulative bone marrow dose of 10 Sv (1000 rem) could be calculated.

Aged↗
PubMed1979

[Radiation exposure of teeth and temporomandibular joints by radiography].

According to a report by Poretti (1975) 21,4% of all medical diagnostic radiographs in Switzerland are dental. In order to determine the associated radiation doses to patients, phantom measurements of skin and gonad exposures were made utilizing modern dental x-ray equipment and techniques. Following procedures in accordance with federal safety regulations it was not possible to measure dose values at the gonad level by single dental or temporomandibular radiographs, even by the most sensitive measuring device. 50 cumulative exposures without lead apron resulted in a range of gonad doses from 3.1 to 199 microR for dental and temporomandibular joint x-rays. Results of skin surface doses ranged from 38 to 289 mR for single dental film exposure and from 64 to 494 mR for single TMJ exposures. Consistent use of parallel technique with long cone equipment, small diaphragms, high kilovoltage and use of the lead apron guarantee great safety against radiation hazard in dental radiography.

Dose-Response Relationship, Radiation↗
PubMed1976

[Clip markings of the uterus and the urinary bladder for the dosimetry of intracavity and percutaneous radiotherapy (author's transl)].

The exact marking of certain regional landmarks of the anatomy permits the determination of the co-ordinates of these points by stereoscopic diagnostic radiology. The mid-point of the upper margin of the symphysis is selected as the origin of the co-ordinates. The markings of the uterus are placed through the laparoscope with silver clips. The markings in the urinary bladder are placed close to the ureteral orifices through the cytoscope. The doses of radiation generated by the sources of radiation (tubes, colpostat, vaginal cylinder, cervical plate) can with this new marking technique not only be measured experimentally in anatomically well-defined points in the body but the dosage (the energy) can be calculated by the computer. In as many points in the body as desired. The maximal permissable dosage in the tumor can be determined with special consideration for the avoidance of radiation lesions to marked adjacent points such as the ureteral orifices.

Computers↗