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R Marchesini

Publications and source records attributed to R Marchesini.

At least 37 records · Page 2Linked to original sources
PubMed1998

[External exposure of hot cell operators in nuclear medicine].

PURPOSE: The coming into effect of decrees No. 626/94, 242/96 and 230/95 has once again brought out the problem of the radiation exposure of hot cell operators in nuclear medicine. MATERIAL AND METHODS: With regard to the activity of the Division of Nuclear Medicine of the Istituto Nazionale Tumori in Milan, a map has been produced of the radiation fields in the hot cell in- and outside the working station by measuring the rate of exposure and evaluating the radiation energy using film dosimeters in multifilter containers. The individual doses were measured with film dosimeters for the sternum, the back of the hand and the wrist, and with thermoluminescent dosimeters for the fingers and forehead. The thermoluminescent ring was worn with the detector towards the palm and towards the back of the hand in order to identify the side that was exposed most; the film dosimeter on the sternum was worn both underneath and above the lead apron to reveal a possible reduction in overall exposure due to attenuation of the lower-energy components. RESULTS: The diffuse radiation field in the hot cell during the usual working activity amounts to 1 microSv/h. Assessment of the energy of the radiation fields within the working station revealed a higher energy (90 to 140 keV) in the source storage area than in the area where the syringes are prepared, the latter being affected by diffuse radiation with components of approximately 35, 90 and 110 keV. The hand of the operator is unevenly exposed to the diffuse radiation field and the fingers are more exposed than the back of the hand and the wrist: when the thermoluminescent ring was worn with the detector towards the palm of the hand the measured values did not show a higher exposure than when it was worn with the detector towards the back of the hand. The equivalent of the overall dose measured underneath the lead apron did not show any relevant reduction of the exposure due to attenuation of the lower-energy component (approx. 35 keV). We report the dosimetric findings regarding the total and partial exposure of four different operators during their regular weekly shift, with the dosimeters for the sternum, ring finger and forehead being replaced daily. The average equivalent of the dose to the hand for the manipulation of 37 GBq of 99mTc, measured with a thermoluminescent ring on the proximal phalanx of the ring finger, ranged 3.9 mSv to 2.0 mSv. Except in one case, the sternum and forehead proved to be well protected by the shielding of the working station. DISCUSSION: The operator who stay in the hot cell for 5 hours/week accumulates, due to the presence of diffuse radiation, 5 microSv/week to the whole body; when his/her hands are inside the working station for 2.5 hours/week in the most unfavorable conditions as regards the presence of radioactive sources, they will be exposed to 1250 microSv/week, independently of dose preparation. The exposure of hot cell personnel is highly dependent on the ergonomics of the operator (build, height, arm spread, hand size, etc.) with respect to the position of the apertures and the inspection windows of the working station; as a consequence, the three dosimetric values (exposure of the sternum, the hands and the forehead) cannot be correlated. The fingers are the most exposed part of the hand, which confirms the appropriateness of our choice of the thermoluminescent ring to measure the partial exposure of the hands. Our results have been compared with those reported in the literature and with statistical data relative to three years of regular activity (1994-1996), during which the hot cell operators were monitored according to the same parameters; female operators proved to be more exposed than males, with average yearly equivalents of the total dose of 2764 microSv and 860 microSv, respectively, and average yearly equivalents of the partial dose to the hands of 32,288 microSv and 9460 microSv, respectively. The average total partial dose equivalent rati

Female↗
PubMed1997

Radiation dose to technicians per nuclear medicine procedure: comparison between technetium-99m, gallium-67, and iodine-131 radiotracers and fluorine-18 fluorodeoxyglucose.

The aim of this study was to determine the non-extremity gamma dose received by a technician while performing an ordinary nuclear medicine procedure or a static (i.e. without blood sampling) fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) study. The dose per patient was measured by means of a commercial electronic pocket Geiger Mueller dosimeter, worn in the upper left pocket of the overalls. This was previously tested by exposure to known point sources of technetium-99m, gallium-67, iodine-131 and fluorine-18 in the air. A further test was performed with 99mTc, 131I and 18F sources inserted in a water phantom to simulate the condition of high scattering degradation of the primary radiation due to the patient's tissues. Subsequently, the dose was measured by two technicians for a total of 314 clinical cases, covering the most common nuclear medicine procedures, including 44 static, two-level FDG PET studies with repositioning of the patient on the couch between the transmission and the emission scan and seven whole-body PET studies. The dose read by the dosimeter was corrected for environmental background and for detector efficiency measured with sources in the air. For a limited subset of cases, the time spent close to patients was also measured. Doses were then estimated by a crude non-absorbing point source approximation and by using experimental dose rates. A comparison between experimental and estimated doses, as well as with previously published data, completed the work. For most of the conventional procedures, the measured dose per procedure proved to be within the range 0.2-0.4 microSv, except for equilibrium angiocardioscintigraphy (1.0+/-0.5 microSv) and 99mTc-sestamibi single-photon emission tomography (1. 7+/-1.0 microSv). Comparison with data published in the last 20 years shows that our values are generally lower. The current more favourable working conditions are a result of technological improvements (for instance two-head gamma cameras capable of whole-body studies), and safer shielding and distance from patients. Two-level PET gave 11.5+/-4.4 microSv and whole-body PET 5.9+/-1.2 microSv. In a subset of patients these values could be subdivided into the separate contributions from each phase of the procedure. They were: 0.11+/-0.04 microSv for daily quality assurance, 2.9+/-3.0 microSv for two transmission scans, 0.3+/-0.1 microSv for syringe preparation, 2.8+/-1.8 microSv for injection and escorting the patient to the waiting room, 1.7+/-1.5 microSv for a whole-body emission scan, 7.7+/-5.2 microSv for two emission scans, and 0.8+/-0. 2 microSv for patient departure. The higher value from PET by comparison with conventional procedures is attributable to the higher specific gamma constant of 18F, as well as the longer time required for accurate positioning.

Fluorine Radioisotopes↗
PubMed1997

[The absorbed dose to the gonads in adult patients undergoing defecographic study by digital or traditional radiographic imaging].

INTRODUCTION: Doses to the gonads and skin of adult people were evaluated during the study of functional anorectal disorders with defecography. MATERIALS AND METHODS: The radiologic procedure relies heavily on fluoroscopy with lateral and anteroposterior projections for a mean time of 2.4 minutes; the stages of interest are recorded on a mean of 6 films. Absorbed doses to the gonads and to the skin were measured with LiF thermoluminescence dosimeters placed inside and outside the anthropomorphic "Rando" phantom. The administered doses during the different examination phases (anteroposterior and lateral fluoroscopy and radiography) were measured. Digital and conventional radiography were compared. RESULTS: Gonadal absorbed doses in a standard DSI examination were: 5.0 +/- .1 mGy to the right ovary, 25.2 +/- .7 mGy to the left ovary and 2.7 +/- .1 mGy to testes when at the margin of the irradiation field. Doses to gonads and skin are about 15% higher when the examination is performed with conventional radiography. DISCUSSION: The considerable radiation dose to ovaries shows that defecography can cause radiation-induced genetic effects in women younger than 40 years with a probability of the order of one thousandth of the natural incidence genetic defects. CONCLUSIONS: Defecography must be correctly indicated in fertile women, because of the relatively high absorbed dose to ovaries. In fact, the ovaries absorb about twice as many radiations during defecography than radiologic examinations of the lower gastrointestinal tract.

Absorption↗
PubMed1996

Interaction of ionizing radiation with topotecan in two human tumor cell lines.

The effect of topotecan, a topoisomerase I inhibitor, on ionizing radiation-induced cytotoxicity was studied in 2 human tumor cell lines characterized by a different expression of the target enzyme. The cytotoxicity of topotecan alone or in combination with radiation was assessed in exponentially growing non-small-cell lung cancer (H460) and glioblastoma (GBM) cells using the colony-forming assay. An isobologram method was used to evaluate the treatment interaction. An apparent supra-additive effect in cell killing following drug-radiation-combined treatment was observed only in GBM cells exposed to topotecan for 24 hr. In the case of H460 cells, interaction varied from a strong infra-additive effect at low radiation doses to a slight supra-additive effect when cells were exposed to radiation doses greater than 3 Gy. Northern blot analysis indicated that topoisomerase I expression in H460 cells was 8-fold higher than that of GBM cells. Although the H460 cell line exhibited an increased sensitivity to topotecan, only in the GBM cell line (which expressed a lower level of topoisomerase I) did the drug potentiate the radiation cytotoxicity. The observation that the radiosensitization by topotecan was related to topoisomerase I level is consistent with a putative role of the enzyme in processes involved in the repair of radiation damage. It is conceivable that the modulation of enzyme function results in an effective reduction of cellular capability for repair of radiation damage only if the enzyme is not over-expressed. Although a precise role of topoisomerase I in the cellular response to ionizing radiations (in particular, in DNA repair) remains to be documented, such results suggest the potential interest of topoisomerase I inhibitors in combination with radiation therapy for tumors expressing low topoisomerase I levels.

Antineoplastic Agents↗
PubMed1996

The invisible colours of melanoma. A telespectrophotometric diagnostic approach on pigmented skin lesions.

Reflectance images of 43 pigmented lesions of the skin (18 melanomas, 17 common melanocytic naevi and eight dysplastic naevi) were acquired by a telespectrophotometric system and were analysed in the spectral range from 420 to 1040 nm, to discriminate melanoma from benign melanocytic entities. Different evaluations were carried out considering the whole spectrum, the visible and the near infra-red. A total of 33 (76.7%) lesions were correctly diagnosed by the telespectrophotometric system, compared with 35 (81.4%) correct clinical diagnoses. Reflectance in the infra-red band appears diagnostically relevant. A larger study is needed to prove the validity of this diagnostic method.

Diagnosis, Differential↗
PubMed1996

Biophysical and biological evaluation of porphyrin-bisacridine conjugates.

Two novel porphyrin-bisacridine conjugates (1 and 2) were designed as bifunctional antitumour agents to combine the DNA-binding character of the acridines and the photosensitizing capacity of porphyrin, and have been subjected to biophysical and biological evaluation. The interactions of the conjugates with calf thymus DNA were evaluated using viscometric, spectrophotometric and stopped-flow sodium dodecyl sulphate (SDS) sequestration methods. Both conjugates acted as bis-intercalators via the two acridine chromophores and displayed a longer residence time on DNA relative to the parent acridine ligand. Their biological activity in vitro was studied against the C6 rat glioma, MCF-7, GBM and A431 cell lines. Both conjugates were cytotoxic to all four cell lines. The ID50 (C6 glioma) was essentially the same as that of the parent acridine for one conjugate, but was increased 20-fold for the other, while both conjugates were approximately 10-fold more cytotoxic than the parent porphyrin component. The tissue distribution of the two conjugates was assessed in nude mice xenografted with a human small cell lung carcinoma (POVD). There were large differences in the tissue distribution of the two conjugates, with conjugate 2 localizing 8-fold more in the tumour than conjugate 1.

Animals↗
PubMed1995

Biodistribution of haematoporphyrin analogues in a lung carcinoma model.

In an attempt to identify novel compounds useful for the optimization of Photodynamic Therapy (PDT), the tissue localization of new synthetic porphyrins was compared with Photofrin II in nude mice xenografted with a human small cell lung cancer (POVD). Three haematoporphyrin analogues were selected for this study based on prior in vitro photosensitivity screening of a series of 15 such derivatives, as well as on the basis of improved localization in C6 gliomas in mice. Two of the porphyrins yielded better tumour:normal lung ratios than Photofrin II and, of these two, one (P13) is known to exhibit good photosensitization properties both in vitro and in vivo, and is therefore a good candidate as a lead compound for the development of porphyrins suitable for the photodynamic treatment of lung tumours.

Animals↗
PubMed1995

Natural fluorescence of normal and neoplastic human colon: a comprehensive "ex vivo" study.

BACKGROUND AND OBJECTIVE: A microspectrofluorometric analysis on "ex vivo" samples from normal tissue and adenocarcinoma of the human colon has been performed to characterize the histological, biochemical, and biophysical bases of the autofluorescence. STUDY DESIGN/MATERIALS AND METHODS: Differences between normal and tumor tissues are found that concern both the intensity distribution and spectral shape of the autofluorescence emission. The different pattern of the fluorescence intensity can be related to the histological organization of the tissue, and involves mainly the arrangement of the submucosa, the most fluorescent layer. RESULTS: The most evident differences in the spectral shape found in the 480-580 nm range involve the stromal compartment, seem to be due to the presence of different fluorochromes, and are possibly related to the host response to the tumor. CONCLUSION: The nature and the extent of the autofluorescence modification between normal and tumor tissue in sections explain at least partly the evidence of the "in vivo" analysis and highlight the importance of excitation for full exploitation of the potentials of autofluorescence in diagnosis.

Adenocarcinoma↗
PubMed1995

Potential and limitations of magnetic resonance imaging for real-time monitoring of interstitial laser phototherapy.

RATIONALE AND OBJECTIVES: Magnetic resonance (MR) imaging has been suggested as a method to monitor interstitial laser phototherapy (ILP) in deep tissues. Unfortunately, a reliable relation between temperature and MR parameters has not yet been demonstrated. In this study, we examined whether such a relation exists and whether MR imaging can measure absolute temperature or temperature changes. METHODS: We evaluated, in the range of 21 degrees C to 80 degrees C, the temperature dependence of the MR imaging signal and T1 in samples of liver, water, CuSO4, and oil. Spin-echo and fast low-angle shot (FLASH) sequences were used. RESULTS: The MR imaging signal of liver, CuSO4, and water continuously decreased when the temperature was increased from 21 degrees C to 80 degrees C. By contrast, the MR imaging signal of the oil increased with increasing temperature up to 40-50 degrees C and then decreased at higher temperatures. We observed a reliable linear relation only between T1 and temperature in a range' of 30-60 degrees C for oil and CuSO4. CONCLUSION: MR imaging has the potential to measure thermal variations with an uncertainty of approximately +/- 10 degrees C. However, the use of MR imaging to monitor the real-time thermal effect induced in biologic tissues during laser irradiation requires further investigation before it can be applied clinically.

Animals↗
PubMed1995

In vivo spectrophotometric evaluation of neoplastic and non-neoplastic skin pigmented lesions. III. CCD camera-based reflectance imaging.

Reflectance spectroscopy, which allows an objective evaluation of the color of surfaces, has recently been proposed as a useful tool to discriminate cutaneous melanoma from other pigmented cutaneous lesions. A novel spectrophotometric system based on the use of a charge coupled device camera provided with a set of interference filters has been developed to acquire images of cutaneous pigmented lesions at selected wavelengths ranging from 420 to 1040 nm. For each filter, an image was captured, digitized by a frame grabber and stored in a personal computer to perform off-line data handling. Reflectance images were acquired of 22 cutaneous pigmented lesions including melanoma and dysplastic, compound and junctional nevus. From each spectral image, three parameters, i.e. mean reflectance, variegation index and lesion area; were derived at the corresponding wavelength. The wavelength dependence of the three parameters was significantly different when melanoma was compared to the other investigated lesions. Although preliminary, our results suggest that telespectrophotometry gives useful information and could be utilized as an aid in the clinical diagnosis of cutaneous pigmented lesions.

Humans↗
PubMed1994

Ex vivo optical properties of human colon tissue.

Using a spectrophotometer equipped with an internal integrating sphere, the absorption (mu a) and the reduced scattering (microseconds') coefficients of ex vivo human colon tissues were evaluated from reflectance and transmittance measurements. Mu a and microseconds' varied from 47.7 to 1.0 cm-1 and from 14.2 to 6.2 cm-1, respectively, on passing from 300 nm to 800 nm. These results can be used to estimate the optical penetration depths when photodynamic therapy or light-induced fluorescence procedures are used.

Absorption↗
PubMed1992

Optical properties of in vitro epidermis and their possible relationship with optical properties of in vivo skin.

Using a spectrophotometer with an internal integrating sphere, the absorption (mu a) and reduced scattering (mu s') coefficients of in vitro epidermis were evaluated from reflectance and transmittance measurements. mu a and mu s' varied from 24 to 0.2 cm-1, and from 32 to 21 cm-1 respectively, on passing from 400 to 800 nm. Moreover, using an external integrating sphere, the reflectance spectrum of in vivo skin was compared with the reflectance spectrum calculated with a Monte Carlo model, in which the mean values of mu a and mu s' and different anisotropy parameters were used as input data. In vivo results show that the principle of similarity is entirely valid for wavelengths greater than 600 nm and may be considered a good approximation in the 400-600 nm band, and suggest that optical characteristics of in vivo skin may be inferred from reflectance measurements.

Adipose Tissue↗
PubMed1992

Light-induced fluorescence spectroscopy of adenomas, adenocarcinomas and non-neoplastic mucosa in human colon. I. In vitro measurements.

In an attempt to evaluate whether induced fluorescence could be exploited to discriminate neoplastic from non-neoplastic tissue, fluorescence spectroscopy was performed at 450-800 nm on 83 biopsy specimens of colonic mucosa. Measurements showed that fluorescence spectra of adenoma, adenocarcinoma and non-neoplastic mucosa manifest dissimilar patterns. Nine variables, whose photophysical and/or biological bases need further investigation, were derived from the spectra. Discriminant functions between the groups of lesions were determined by using a stepwise discriminant analysis. The diagnostic test had a sensitivity of 80.6% and 88.2%, and a specificity of 90.5% and 95.2% in discriminating neoplastic from non-neoplastic mucosa and adenoma from non-neoplastic mucosa respectively. These results suggest that fluorescence spectroscopy has the potential to improve endoscopic diagnosis of premalignant and malignant lesions of colonic mucosa.

Adenocarcinoma↗
PubMed1992

In vivo spectrophotometric evaluation of neoplastic and non-neoplastic skin pigmented lesions. II: Discriminant analysis between nevus and melanoma.

Reflectance spectrophotometry from 420 to 780 nm on 31 primary melanoma and 31 benign nevi has been performed by using an external integrating sphere coupled to a spectrophotometer. Measurements show that reflectance spectra of melanoma and nevi manifest dissimilar patterns. From these spectra four variables, whose physical and/or physiological meanings remain to be investigated, have been derived. All of them are significantly different when compared between melanoma and nevi. A discriminant function between the two groups of lesions has been determined by using a stepwise discriminant analysis, resulting in a test with a sensitivity of 90.3% and a specificity of 77.4%. This method of discrimination between melanoma and nevi seems to have a discriminating power almost equal to that of a clinical judgement from a specialized medical doctor, thus suggesting a new method for screening skin pigmented lesions.

Diagnosis, Differential↗
PubMed1991

In vivo spectrophotometric evaluation of neoplastic and non-neoplastic skin pigmented lesions--I. Reflectance measurements.

Reflectance spectrophotometry from 400 to 800 nm on different cutaneous pigmented lesions, including primary and metastatic malignant melanoma, pigmented nevi, lentigo and seborrhoeic keratosis, has been performed by using an external integrating sphere coupled to a spectrophotometer. Measurements show that reflectance spectra of the different lesions manifest dissimilar patterns, particularly in the near IR region. Comparison of reflectance of nevi with that of malignant melanomas results in a highly significant difference (P less than 10(-6)) between the two samples. Though interpretation of the spectra remains difficult as a result of the complexity of the optical processes of scattering and absorption, our results suggest that a detailed analysis of the reflectance spectrum may give clinically useful information, and could be utilized as an aid in clinical diagnosis of cutaneous pigmented lesions, especially where malignant melanoma is concerned.

Humans↗
PubMed1990

Photodynamic therapy by topical meso-tetraphenylporphinesulfonate tetrasodium salt administration in superficial basal cell carcinomas.

The efficacy of an originally developed photodynamic approach, using topical administration of tetraphenylporphinesulfonate as the photosensitizer, was evaluated in a series of 292 basal cell carcinoma lesions (less than 2-mm thick) in 50 treated patients. The lack of indication for conventional therapies was the main selection criterion. The photosensitizing agent (2% solution) was topically applied at 0.1 ml/cm2, followed by light irradiation with a dye laser emitting at 645 nm (120 or 150 J/cm2). After initial treatment, all lesions responded, with 273 (93.5%) complete responses. Recurrences were observed in 29 (10.6%). A second application of photoradiation was performed in 15 persistent lesions and 11 relapsed lesions, producing 19/26 complete responses. Our results suggest that this technique can be considered a promising alternative treatment modality in selected cases of superficial basal cell carcinomas.

Aged↗
PubMed1989

Effect of low-energy laser irradiation on colony formation capability in different human tumor cells in vitro.

Fibroblasts and lymphocytes are the most widely used cells for studying the so-called biostimulative effect of low-power laser in vitro. In contrast, stimulation of cancer cells by laser light has not been investigated extensively. The present study attempted to evaluate whether or not human tumor cells could exhibit an increase in colony-forming capability following low-watt laser irradiation. LoVo and HT29 (colon carcinoma), MCF7 (breast carcinoma), M14 and JR1 (malignant melanoma) cell lines were irradiated at different doses of light delivered from an argon or an argon-dye laser. Radiant exposures between 4.2 and 150 kJ/m2 at irradiances ranging from 35 to 500 W/m2 were delivered. Results were mixed. Of the 41 experiments performed, five showed a significant statistical increase in the number of colonies (P less than 0.05), whereas three showed a decrease (P less than 0.05). Nevertheless, the trend of most data was toward an increase in colony formation, and Wilcoxon's signed-ranks test suggested that light increases tumor cell culture growth (P less than 0.03).

Breast Neoplasms↗