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Biomedical subjects

M Galelli

Publications and source records attributed to M Galelli.

10 recordsLinked to original sources
PubMed1999

Dosimetry study in patients with autonomous thyroid nodule who are candidates for radioiodine therapy.

UNLABELLED: A dosimetry study was performed on 26 patients with an autonomous thyroid nodule and suppressed serum thyroid-stimulating hormone, to determine the dose to extranodular tissue when the nodule receives 300 Gy for 131I therapy. METHODS: Parameters of radioiodine turnover to be used in the dosimetry formula were separately obtained for the nodule and the contralateral lobe, as a measurable example of the extranodular tissue, using 55 MBq 123I and a computer-assisted gamma camera. The biologic half-life of 123I was then converted into the effective half-life of 131I, and the volumes of the nodule and the lobe were obtained by scintigraphy or sonography. RESULTS: The mean dose to the contralateral lobe from uptake and irradiation by the nodule was calculated to be 32 Gy, and that to the ipsilateral lobe was estimated to be 34 Gy. CONCLUSION: During radioiodine therapy for autonomous thyroid nodules, the extranodular tissue receives a higher dose than is generally assumed, which explains the relatively high rate of post-treatment hypothyroidism reported in the literature.

Female↗
PubMed1997

[Intracavitary brachytherapy in esophageal neoplasms. Experience at the Radiology Institute of Brescia].

We investigated the role of brachytherapy in the management of esophageal cancer. From March, 1990, to December 1994, seventy patients, with biopsy-proved esophageal carcinoma, were treated with brachytherapy +/- external beam radiotherapy. According to the TNM staging system, 24 patients were graded as T1, 24 as T2, 10 as T3, 9 as T4, and 3 as Tx. Median Karnofsky score was 80. Dysphagia was the major symptom in 68% of cases. Treatment consisted of low dose rate first, and then high dose rate brachytherapy, with progressive optimization of doses and fractions, up to total doses of 15-30 Gy in low dose rate and 7-21 Gy in high dose rate. When associated, external beam radiotherapy was delivered with conventional schedules. Tolerance to treatment was good with slight acute toxicity. Symptoms were markedly improved, with reduction of dysphagia in 100% of cases. Overall survival was 75%, 47%, 23% and 18% at 6, 12, 24, 36 months; no significant difference was found between low and high dose rate groups. Furthermore, no difference was shown in the overall survival of the group treated with brachytherapy alone and the one with associated external beam radiotherapy. Late toxicity occurred in 10% of patients and was managed by endoscopic procedures in all cases. In our opinion, brachytherapy appears to be an effective palliative treatment; its role as radical treatment remains to be defined.

Adult↗
PubMed1995

Dosimetry of 169 Yb seed model X1267.

Unlike previous brachytherapy sources a number of published studies have been addressed to the dosimetry of 169 Yb seeds, manufactured in several prototypes, before widespread clinical use has been made. Discrepancies seen in the dosimetry obtained for ytterbium seed prototypes appear to be related to inconsistency and non-reproducibility in the vendor's calibration procedure to determine contained activity. Av. The comparison of 169 Yb seed dosimetries demonstrates a need for more accurate implementation of calibration procedures to determine the air kerma rate for the definitive 169 Yb seed design. This paper reports an experimental procedure to determine the reference air kerma rate, Kr (mu Gy h-1), defined as the kerma rate at 1 m along the source transverse axis in free space for the new 169 Yb seed, model X1267. A mean value of the ratio Kr/Av = 1.53 mu Gy h-1 mCi-1 was obtained from determining the Kr value of eleven seeds. Since this ratio is only 3% less than the air kerma rate constant for the 169 Yb point source, (gamma delta)k = 1.58 mu Gy h-1 m2 mCi-1, this means that the Av is closer to an apparent activity than a contained activity, Ac. A Monte Carlo simulation to determine the ratio between reference air kerma rate and the contained activity gave Kr/Ac = 1.33 mu Gy h-1 mCi-1. For the dose rate constant in water we obtained DKr (1, pi/2) = 1.20 +/- 0.05 cGy h-1 (mu Gy h-1)-1, using calibrated thermoluminescent dosimeters (TLDs) and DKr (1, pi/2) = 1.21 +/- 0.03 cGy h-1 (mu Gy h-1)-1 by Monte Carlo simulation. TLDs were used both to determine the radial dose distribution along the seed transverse axis and to calibrate GAFChromic films to obtain the two-dimensional dose distribution around the seed.

Biophysical Phenomena↗
PubMed1994

High-dose interstitial brachytherapy for glioblastoma multiforme.

AIMS AND BACKGROUND: The long-term prognosis for survival of patients with inoperable glioblastoma multiforme (GBL) is very poor. Conventional external radiotherapy gives only transitory result. This severe prognosis led us to elaborate a high-dose rate (HDR), after-remote-loading brachytherapy treatment protocol: our aim was both therapeutic and psychologic. METHODS: Five patients with GBL (T1 G4 UICC) were treated with stereotactic biopsy followed by HDR brachytherapy. A unique coaxial after-loading catheter was stereotactically inserted through the center of the target volume. The treatment schedule considered 5 fractions, 5 Gy/fraction at the dose specification surface, 2 fractions per day. RESULTS: The treatment was well tolerated. Tumor progression started again at the 8th to the 16th week from the end of the treatment. ECOG performance status at the 8th week was better than before the therapy in 2 of 5 patients and was stable in 2 of 5 patients. Order neuroperformance status was stable in 2 patients at 8 weeks. At the 16th week there was neurologic deterioration. The average survival was 21 weeks. CONCLUSIONS: Our approach seems to be of some interest for the palliation of GBL, and it offers some advantages, in particular regarding the short treatment period. Our procedure can be improved: a multi-catheter implant and a more fractionated schedule could be taken into account.

Aged↗
PubMed1994

Decreased incorporation of 14C-leucine in different liver nuclear protein fractions at early stages of carbon tetrachloride poisoning in the rat.

Administration of CCl4 to 12-14 h starved Sprague Dawley male rats (220-240 g) at a dose of 5 ml of a 20% (v/v) olive oil solution/kg i.p. decreased the incorporation of 14C-leucine into microsomal and nuclear proteins at 1 or 2 h after the hepatotoxin. Decreased amino acid incorporation capacity in nuclear but not in microsomal proteins returned to control values at 4 h after poisoning. Cycloheximide given i.p. at a dose of 1 mg/kg in saline either alone or before CCl4 also decreased to a similar or greater extent the incorporation of 14C-leucine into both, microsomal and nuclear proteins at 1 h. The CCl4-induced decrease in amino acid incorporation was observable and significant even 1 h after CCl4 and involved histone and different non-histone nuclear protein fractions. Results suggest that decreased protein synthesis at the endoplasmic reticulum occurring in the very early stages of CCl4 poisoning might provoke temporary deficiencies in protein supplies to nuclei with as yet unknown consequences. However, some of the proteins involved have major regulatory properties in DNA expression.

Animals↗
PubMed1992

A comparison of accuracy of computer treatment planning systems in brachytherapy.

An intercomparison was made between dose-rate point calculations with five commercial computer treatment planning systems used in brachytherapy. Sixteen Italian radiotherapy medical physics institutions performed a twofold test, respectively for point and linear sources, reproducing actual clinical implants and the results were compared to references values. The test was designed in order to determine the errors introduced separately by computation and by implant reconstruction via orthogonal films. The results show that for point sources a better accuracy can be achieved than for linear sources. It is also shown that a large variation of results exists between computation systems and the variability is larger for linear sources. The digitizing procedure adds a large amount of error. In the whole set of calculation points, the overall percent difference between computed and reference dose-rate values is larger than +/- 5% in 18% cases for point and in 52% cases for linear sources, with data input by digitizer. It seems that relevant errors do occur when computing actual dose rates, resulting in clinically relevant inaccuracies in the calculated absorbed dose and in its relative effectiveness.

Algorithms↗
PubMed1991

Resampling algorithms for diagnostic radiology.

The use of digital image resampling can be highly suitable for diagnostic radiology. It can be applied not only to obtain zoom effects but also to solve various problems related to the comparison of images of different origin (NMR, CT, NM). The mathematical approach to this kind of algorithm, based on rational assumptions, can be very wide and diversified. In this work the principles of the stochastic and of the analytical methods have been analyzed. In particular, a complete mathematical treatment of the integral analytical methods, which are both the most theoretically interesting and analytically complex, has been performed. The practice of these techniques has to be determined each time from the analysis of the specific problem to which they are to be applied in the routine, and after a retrospective analysis of the results obtained.

Algorithms↗
PubMed1990

[Simulation of an instrumental head for 6 MeV electron beam therapy].

Simulation of a therapy head for 6 MeV electron beams. We present the results of a simulation, performed using a Monte Carlo method, of depth dose curves in water for electron beams of initial kinetic energy of 6.4 MeV, generated by a radiotherapy microtron MM22 Scanditronix. The Fortran code in EGS4: comparison is made between simulated curves, obtained using various approximation criteria, and the experimental one.

Electrons↗
PubMedDate not supplied

High-dose-rate brachytherapy for poor-prognosis, high-grade glioma: (phase II) preliminary results.

AIMS AND BACKGROUND: The purpose of this study was to investigate the palliative effectiveness of an interstitial fractionated high-dose-rate (HDR) brachytherapy regimen in patients with poor-prognosis, high-grade glioma. METHODS: An after-remote-loading microSelectron HDR lr-192 370 GBq unit was used. A unique coaxial after-loading catheter was stereotactically inserted through the center of the target volume. The treatment schedule was: 5 fractions, 5 Gy per fraction, or alternatively 7 fractions, 3.85 Gy per fraction, at the dose specification surface, 2 fractions per day. Twenty-four patients have been treated: in 17 of them (T1 G3-4) the catheter was implanted during stereotactic biopsy procedure; in the other 7 cases (T2 G3-4), subjected to partial resection and reduced to yT1, the catheter was implanted following surgery with a mean delay of 15 days. RESULTS: The treatment was feasible and well tolerated. The complete course takes no more than 7 days. The acute complication rate (2/24) seems to be acceptable. The median survival was 8 months. No less than 45% of the patients had a WHO grade 2 score or better at any time of follow-up. At 4 months of follow-up, functional status, assessed using a verbally administered Barthel index, had improved from the pretreatment level in 29.1% of the 18 surviving patients and remained stable in another 22.2%. A minimal response or stable disease, according to CT scan, was obtained in about half of the assessable survivors at any time of follow-up. CONCLUSIONS: The short course of brachytherapy provides a good palliation in terms of functional improvement in a high proportion of patients, with low and acceptable toxicity.

Actuarial Analysis↗