E.M. Yoshimura

EFFECTS OF LOW-LEVEL LASER THERAPY ON COLLAGEN EXPRESSION AND NEUTROPHIL INFILTRATE IN 5-FLUOROURACIL-INDUCED ORAL MUCOSITIS IN HAMSTERS

Several studies have suggested that low‐level laser therapy (LLLT) can ameliorate oral mucositis; however, the mechanisms involved are not well understood. The aim of this study was to investigate the mechanisms of action of LLLT on chemotherapy‐induced oral mucositis, as related to effects on collagen expression and inflammation.

How safe is ERCP to the endoscopist

AbstractBackground: Interventional techniques in endoscopy such as endoscopic retrograde cholangiopancreatography (ERCP) have greatly increased since laparoscopic cholecystectomy has become widespread; mainly these techniques deal with common bile duct stones. Fluoroscopy is usually employed, and chronic exposure to X-ray, in spite of the relative low dose, can lead to potentially unhealthy conditions such as malignancies like bone marrow and other solid cancers. A median of 18 years of life is lost per fatal cancer, including the time of latency since exposure. Nor should one forget benign condition such as cataracts that can lead to partial or complete blindness and which surely impair lifes quality. Methods: Simulated examinations were carried at the University Hospital (São Paulo, Brazil) using an anthropomorphic phantom in place of the physician. Four sets of dosimeters were placed in the forehead, neck, torso, and lower abdomen (with and without a lead apron) and standard ERCP fluoroscopic techniques were employed. Results: The dose equivalents were calculated and compared to the recommended exposure doses of national and international boards of radiation protection. Conclusions: Based on the results found and compared to standards, working safely means: (1) A lead (0.5 mm thickness) apron is fundamental. Without it less than one ERCP\/month should be performed. (2) With an apron, 23 examinations/month are allowed. (3) No thyroid protection grants only 19 exams/month. (4) Performing ERCP without lead glasses is hazardous to the eye, allowing only seven ERCPs monthly.

Occupational exposure to radon and natural gamma radiation in the La Carolina, a former gold mine in San Luis Province, Argentina

Radon and gamma radiation level measurements were carried out inside the La Carolina mine, one of the oldest gold mining camps of southern South America, which is open for touristic visits nowadays. CR-39 track-etch detectors and thermoluminescent dosimeters of natural CaF(2) and LiF TLD-100 were exposed at 14 points along the mine tunnels in order to estimate the mean (222)Rn concentration and the ambient dose equivalent during the summer season (November 2008 to February 2009). The values for the (222)Rn concentration at each monitoring site ranged from 1.8+/-0.1 kBqm(-3) to 6.0+/-0.5 kBqm(-3), with a mean value of 4.8 kBqm(-3), indicating that these measurements exceed in about three times the upper action level recommended by ICRP for workplaces. The correlations between radon and gamma radiation levels inside the mine were also investigated. Effective doses due to (222)Rn and gamma rays inside the mine were determined, resulting in negligible values to tourists. Considering the effective dose to the mine tourist guides, values exceeding 20mSv of internal contribution to the effective doses can be reached, depending on the number of working hours inside the mine.

Supralinearity and sensitization of thermoluminescence. I. A theoretical treatment based on an interactive trap system

A theoretical treatment is presented for the supralinearity of thermoluminescence glow peaks. The model assumes part of the thermoluminescence trap population as interactive with the thermally disconnected deep traps. These traps produce supralinear growth of the thermoluminescence response. The initial linear part of the response curve is assumed to be produced by the non-interactive part of the thermoluminescence trap population. The treatment enables determination of the relative concentration of deep traps. Resolution of the observed response curve into linear and supralinear parts allows determination of the relative trap populations responsible for producing the linear and supralinear parts of the response. We have also shown the procedure for determining the trap filling constant using the growth profile of the thermoluminescence glow peak of pre-dose sensitized samples. Apart from interpreting the linear and supralinear behaviour of the thermoluminescence response, the treatment provides a quantitative explanation for the pre-dose sensitization effect.

Gamma ray contribution to the ambient dose rate in the city of São Paulo, Brazil

Abstract The gamma contribution to the dose received by the population in the city of Sao Paulo, Brazil, was evaluated. Gamma ray spectroscopy with a sodium iodide scintillation detector was chosen as the technique, by the easiness of use, high sensitivity and possibility of identification of an inadvertent contamination. Measurements were taken at 1 m from the ground, outdoors (at the streets) and indoors (at commercial places). Besides the gamma spectra, the ambient dose equivalent rates were assessed. It was found that in average the indoor dose rates are 46% higher than the outdoor values. No statistically significant cluster of dose values was found in the distribution of outdoor values over the city territory, although a non-homogeneous pattern is observed. As far as the indoor sample is concerned, the statistical analysis points to different mean values, according to the category of the commerce. A final conclusion is that the ambient dose equivalent values observed are high when compared to other places of the world.

Supralinearity and sensitization factors in thermoluminescence

Abstract Supralinearity and pre-dose sensitization are two characteristics of thermoluminescence (TL) glow peaks which are seen together in many of the TL phosphors. In this paper, theoretical expressions are derived for the supralinearity and pre-dose sensitization factors, based on the interactive trap system model. A new term called sensitization factor ( S n F ) is introduced, which differs from the pre-dose sensitization factor ( PDSF ) but is related directly to the supralinearity factor ( SF ). The factors SF and S n F coincide in the low and medium dose range. At high doses the latter departs considerably from the former. The case of LiF TLD-100 is used to demonstrate the application of the theory to actual experimental results.

Supralinearity and sensitization of thermoluminescence. II. Interactive trap system model applied to LiF:Mg,Ti

For Part I see ibid., vol.27, pp.852-60 (1994). A theoretical treatment based on a partly interactive trap system (PITS) described in Part I is applied to peak 5 of LiF:Mg,Ti. The model assumes two types of thermoluminescence traps for the given glow peak: (i) those which produce a linear response with dose and (ii) those which produce a supralinear response. The former are spatially associated with the luminescent recombination centres. The latter are randomly distributed and the carriers released from them during readout heating may be recaptured by the thermally disconnected deeper traps non-radiatively in addition to undergoing recombination to produce luminescence. The trap filling constant, defined as the fraction of traps filled per unit dose, is determined using the intensity growth profile of the related optical absorption band and that of the thermoluminescence of pre-dose sensitized sample. The value of this constant is 1.16*10-3 Gy-1 for peak 5. For peak 12 it is an order of magnitude lower. Fractions of the thermoluminescence trap population responsible for linear and supralinear parts of the response are determined using pre-dose sensitization. The ratio of these two populations is calculated to be 1:13. A method is suggested to determine the relative concentration of the deep traps with respect to the shallower thermoluminescence traps. This estimation is carried out by separating the supralinear part of the response curve and calculating its under response factor at low doses. The relative concentration of deep traps is seen to be dependent on the relative coefficients for trapping and recombination. The calculated parameters are backfitted into the theoretical expression and the response profile so obtained is compared with the experimental response curve. The two are found to be in good agreement.

Low‐level laser therapy in chronic autoimmune thyroiditis: A pilot study

Chronic autoimmune thyroiditis (CAT) remains the most common cause of acquired hypothyroidism. There is currently no therapy that is capable of regenerating CAT‐damaged thyroid tissue. The objective of this study was to gauge the value of applying low‐level laser therapy (LLLT) in CAT patients based on both ultrasound studies (USs) and evaluations of thyroid function and thyroid autoantibodies.

Diagnostic reference levels for the most frequent radiological examinations carried out in Brazil

OBJECTIVES A large-scale survey of doses to patients undergoing the most frequent radiological examinations was carried out in health services in São Paulo (347 radiological examinations per 1 000 inhabitants), the most populous Brazilian state. METHODS A postal dosimetric kit with thermoluminescence dosimeters was used to evaluate the entrance surface dose (ESD) to patients. A stratified sampling technique applied to the national health database furnished important data on the distribution of equipment and the annual number of examinations. Chest, head (skull and sinus), and spine (cervical, thoracic, and lumbar) examinations were included in the trial. A total of 83 rooms and 868 patients were included, and 1 415 values of ESD were measured. RESULTS The data show large coefficients of variation in tube charge, giving rise to large variations in ESD values. Also, a series of high ESD values associated with unnecessary localizing fluoroscopy were detected. Diagnostic reference levels were determined, based on the 75th percentile (third quartile) of the ESD distributions. For adult patients, the diagnostic reference levels achieved are very similar to those obtained in international surveys. However, the situation is different for pediatric patients: the ESD values found in this survey are twice as large as the international recommendations for chest radiographs of children. CONCLUSIONS Despite the reduced number of ESD values and rooms for the pediatric patient group, it is recommended that practices in chest examinations be revised and that specific national reference doses and image quality be established after a broader survey is carried out.

Some effects of γ-irradiation in soda-lime silicate glasses

Abstract Nanosized metallic silver particles have been formed in multicomponent commercial soda-lime silicate glasses partly substituted with ionic silver and irradiated at room temperature by γ-rays from a 60Co-source (1.33 MeV). To characterize the obtained composites, combined measurements of thermally stimulated depolarization current and optical absorption, accompanied by microspectrophotometric analysis and electron microscopy observations have been used. It has been shown that γ-irradiation might be an effective means to modify and control the concentration, size and spatial distribution of the dopant within the near-surface layer of the glass-matrix. This procedure also allows the conversion of some glassy areas in this region into a partially crystalline material with improved mechanical characteristics.