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Biomedical subjects

F Cattani

Publications and source records attributed to F Cattani.

At least 19 recordsLinked to original sources
PubMed2004

Comparative study of permanent interstitial prostate brachytherapy post-implant evaluation among seven Italian institutes.

BACKGROUND AND PURPOSE: The purposes of this multicentric study are (a) the evaluation of four different commercially available treatment planning systems (TPSs) and (b) to verify whether the dosimetric results are comparable, also when considering the inter-observer variabilities and the different scanning protocols used. This work is to be considered a first step to test the value of multicentric studies based on dosimetric evaluation of the quality of the implants. PATIENTS AND METHODS: Four different TPSs were used and the following tests were performed:Comparison of the parameters and mathematical algorithms used; comparison of the dose distributions generated by three different geometries of sources based on 32 dose-points on each source geometry. An octagonal geometric phantom was used to compare volume algorithms and dose-volume histogram (DVH) calculations (V150(Gy), V100(Gy), V50(Gy) and V25(Gy)). Comparison of the post-plan source distribution performed on a prostate-phantom implanted with (125)I seeds. A CT scan of the phantom was obtained at each participating center. Both the geometrical coordinates (with respect to the most caudal one), and the spread of the geometrical distribution, were calculated. The volumes included within different isodoses were also collected. Comparison of the post-plan source distribution performed on an actual patient. Post-plan V100% and D90(Gy) derived from seed distributions obtained by different operators were calculated, using the same target delineation. RESULTS: All the considered TPSs satisfied the AAPM dosimetric parameter recommendations. Point-dose examinations revealed differences smaller than 5%, except for one of the systems. Although the volume algorithm was not the same for all systems, no statistically significant difference was found in the volume measurements. The DVHs also presented differences smaller than 5%, except for one TPS. The distances between the seeds, based on the same CT images, showed a mean SD of 0.13 mm. The mean maximum difference of the position of each seed was 0.36 mm. The most significant errors were made in the cranio-caudal direction (mean maximal difference: 0.44 mm); here the size of the step between slices played an important role. The algorithm of source positioning of the different TPSs may also help explain this difference. The compiled DVHs showed differences smaller than 5%. Post-plans derived from different seed distributions showed a mild dependence upon operators. We obtained a mean value of 97.8 and 152.7 with a percentage of SD of 0.43 and 1.7, respectively, for V100% and D90(Gy). CONCLUSIONS: Three-dimensional (3D) geometric reconstructions of seed distributions are slightly dependent upon the operators and the scanning protocols have little effect on the dosimetric evaluation. Some relevant discrepancies were found between one of the TPSs and the other three if few sources were used; increasing the number of seeds those differences became less pronounced. Multicentric studies on the quality of prostate implants based on post-implant dosimetry are feasible, provided an accurate step-wise evaluation of the procedure be performed.

Aged↗
PubMed2002

Axisymmetric relativistic self-channeling of laser light in plasmas.

By using an improved cavitation model, relativistic self-channeling structures are derived, which make it possible to propagate laser powers exceeding the critical one for self-focusing. A propagation mode for high laser power is also presented which is qualitatively different from those in the weakly relativistic case. Structural stability analysis shows that stable self-wave-guide propagation can take place.

Journal Article↗
PubMed2001

Electromagnetic energy penetration in the self-induced transparency regime of relativistic laser-plasma interactions.

Two qualitatively different scenarios for the penetration of relativistically intense laser radiation into an overdense plasma, accessible by self-induced transparency, are presented. In the first one, penetration of laser energy occurs by solitonlike structures moving into the plasma. This scenario occurs at plasma densities less than approximately 1.5 times the critical one (depending on ion mass). At higher background densities, laser light penetrates only over a finite length which increases with incident intensity. In this regime the plasma-field structures represent alternating electron (and, on longer time scales, ion) layers separated by about half a wavelength of cavitation with concomitant strong charge separation.

Journal Article↗
PubMed2001

Multifilament structures in relativistic self-focusing.

A simple model is derived to prove the multifilament structure of relativistic self-focusing with ultraintense lasers. Exact analytical solutions describing the transverse structure of waveguide channels with electron cavitation, for which both the relativistic and ponderomotive nonlinearities are taken into account, are presented.

Journal Article↗
PubMed2001

Developmental expression and distribution of amphibian glutathione transferases.

This work is aimed at detecting the expression and location of embryonic Bufo bufo GST (bbGSTP1-1) and adult B. bufo GST (bbGSTP2-2) during toad development, in order to assign a putative role to these enzymes also on the basis of their compartmentalization and to verify whether during the premetamorphic liver ontogeny the bbGSTP2-2 form appears. This study was also performed in the adult liver (the primary site of Pi class GST expression) and in the mature ovary, to discern if the embryonic form derives from maternal form. The results show that the embryos and the ovary express only bbGSTP1-1. Moreover, bbGSTP1-1 distribution is the same both in the early embryos and in the ovary: this strongly suggests that bbGSTP1-1 is of maternal origin. As development goes on, a wide distribution of bbGSTP1-1 all over the differentiating organs is observed. The embryonic liver expresses exclusively the bbGSTP1-1 form, while the adult liver is highly positive only towards the bbGSTP2-2 form. This implies that the switch towards the adult bbGSTP2-2 form occurs in metamorphic or postmetamorphic phases and that the detoxication metabolic requirements of the embryo may be completely fulfilled by the bbGSTP1-1 isoenzyme.

Animals↗
PubMed2000

Threshold of induced transparency in the relativistic interaction of an electromagnetic wave with overdense plasmas

An exact analytical investigation of the stationary solutions describing the interaction between high-intensity laser radiation and an overdense plasma is presented. Both the relativistic and striction nonlinearities are taken into account, and their joint action gives rise to a solitary solution. This solution clearly shows that there exists an inherent limit of the induced transparency on the density of the overdense plasma in order to obtain a stationary physical solution. Furthermore, it is found that the striction nonlinearity tends to create a strong peaking of the plasma electron density, which suppresses the laser penetration and significantly enhances the threshold intensity for induced transparency.

Journal Article↗
PubMed1997

[Intracranial meningiomas in the elderly].

BACKGROUND: Since the introduction of CT and then MRI in the clinical practice, the number of elderly patients with intracranial meningiomas observed in neurosurgical departments has increased to three/four times. Considering that some patients die because of their meningioma and others die with their meningioma, the neurosurgeon should not only be able to eradicate surgically the lesion, but also to decide if that benign tumor should be treated or not. MATERIALS AND METHODS: Forty-three patients with intracranial meningioma, aged over 65 were operated upon between 1989 and 1995. They constitute about one fourth of all the meningioma-patients operated upon in that period at our Department. Main symptoms were focal deficits, psychorganic syndrome, and seizures. Mean duration of symptoms was 15 months, with 30% of the histories lasting less than 3 months. Associate pathologies were those typical of the elderly population with hypertension and senile cardiopathy at the first places. Two patients had insulin-dependent diabetes, 2 prostatic carcinoma, and 8 were obese. MRI was useful either in depicting the location of the tumor or in helping the surgeon to give a correct operative indication and risk evaluation. MRI criteria for risk evaluation were severe edema and venous vascular infiltration. Forty-five operations were performed. Their duration was not a risk factor by itself, it only reflected the difficulty of the removal, due to the location of the tumor. Dissection of tumor remnants from main arteries or veins was never attempted in this group of patients; total removal was achieved in 75.5% of the cases. RESULTS: Immediate postoperative results were good in 71% of cases. Four patients died (9%). Long term results were evaluated in 29 patients (mean follow-up period: 35 months). Twenty-two patients (76%) had excellent or good results, 5 (17%) fair, and 2 (7%) had severe neurological dysfunctions and needed continuous assistance. CONCLUSIONS: Surgical risk factors typical of this age group were identified: cranio-spinal location, damage to the cortical or deep venous system, severe peritumoral edema, and poor neurological preoperative conditions. Systemic risk factors were insulin-dependent diabetes and obesity.

Age Factors↗
PubMed1993

Absorbed dose from contaminant electrons inside and outside megavoltage photon beams.

Megavoltage photon beams interactions with any object on their path give rise to secondary photons and electrons. This fact is particularly important in Radiotherapy. These secondary particles produce an unwanted dose contribution both on beam path and outside the geometrical edges of the irradiation field. The goal of this report is to investigate the dose contribution due to secondary electrons. Ionization measurements were made in a polystyrene phantom by means of a Markus ionization chamber, with X-ray beams produced by a "SL5" Philips and by a "Saturne 43" GE CGR linear accelerators. Specific fields for nasopharynx treatment and for supra-diaphragmatic lymphatic chains treatment ("mantle" fields) were investigated. Both depth ionization values on beam path and depth and surface ionization values outside the geometrical edges of the field were obtained. These measurements were made with and without specific electron filters for 6, 15, 25 MV X-ray beams. The results obtained prove that, both on the beam path and outside the geometrical borders of the field, electron contamination reduction by means of specific filters is important only for lower energy X-ray beams. For this sort of beams, the percentage reduction of electron contamination was found. Moreover, the amount of electron contamination outside the field geometrical edge versus field size was evaluated.

Absorption↗
PubMed1990

Mucocele of neurosurgical interest: clinical considerations on five cases.

The authors present five patients with mucocele, submitted to neurosurgery. Two had mucoceles spreading from the frontal and/or the anterior ethmoidal sinuses and had only compressive mass symptoms, either on the ocular globe or on the frontal lobe or on both. Three patients had mucoceles growing from the sphenoid and/or posterior ethmoidal sinuses. In these latter, the mass symptoms were less evident. All the patients suffered excruciating retro-ocular pain and two presented cranial nerve damage. The correct diagnosis in these cases is crucial to avoid a too aggressive treatment since these patients are generally sent to a neurosurgeon for a suspected cranial base malignancy or an invasive pituitary adenoma. The principles of a correct differential diagnosis and of operative treatment are outlined based on an analysis of the literature and the authors experience.

Adult↗
PubMed1989

The potential role of lonidamine (LND) in the treatment of malignant glioma. Phase II study.

Up-to-date unsatisfactory results obtained in multimodality treatments of malignant glioma have prompted the research of new therapeutic modalities with 'unconventional' modes of action. Lonidamine (LND) is a drug which reduces aerobic glycolytic activity in both human and experimental tumors. This effect mainly depends on the inhibition of mitochondrially-bound hexokinase (HK) which is present in large amounts in malignant cells. A Phase II study was conducted on patients with recurrent glioma; 12 patients were admitted to the study. Clinical side effects were moderate, necessitating a reduction of the dosage in only 1 case. The objective results were evaluated according to the indications of Levin. 2 responders and 3 cases of stable disease were observed out of 10 evaluable patients. The potential value of this new drug is discussed.

Adolescent↗
PubMed1980

[Ocular complications in patients undergoing long-term hemodialysis and renal transplants from cadavers].

In 36 subjects in chronic hemodialysis treatment and in 36 patients with a renal transplant, well functioning for more than one year, the ocular complications related to the specific form of treatment were evaluated and compared. In the group of the dialyzed subjects ocular pathology was composed by: lens opacities in 9 cases, corneal calcifications in 7 cases, hypertensive fundus in 8 cases. In no patient these lesions produced measurable visus reductions. In the transplant group ocular pathology was composed by: lens opacities in 28 patients, hypertensive fundus in 7 and intraocular hypertension in one. One case of herpes cheratytis and one case of endophtalmytis have also been observed. In 9 patients these lesions produced a remarkable visus reduction. In conclusion renal transplantation shows a greater incidence of ocular complications if compared to hemodialysis. This situation has not important consequences on the rehabilitation of the transplanted subject for the possibility of surgical correction of the cataract.

Adolescent↗