Search

This is a study of our experience with Co-60 high dose rate brachytherapy (HDR BT) from a tertiary care center. One thousand patients were treated with Cobalt-based HDR BT for more than 6 years. The practice of BT was analyzed for clinical outcome, physical, radiobiological, and technical aspects. Among those 1000 patients, 906 (90.6%) patients had gynecologic cancer, 29 (2.9%) patients had intraluminal BT, 63 (6.3%) hadhead &neck (2.1%), keloid (2.1%) and mold BT (2.1%), and 2 (0.2%) had sarcoma. Dose rate decreased by 48.9%, and treatment time increased from 9.33 to 18.27 min over 5 years. No patients treatment was abandoned because of machine-related problems. Cobalt-based HDR BT is preferable in terms of lesser source exchanges, relatively uniform treatment time, quality assurance requirement, and cost. [ABSTRACT FROM AUTHOR]

Purpose The main objective of our study is to evaluate response and toxicity profile in patients receiving external beam radiotherapy with concurrent chemotherapy followed by intraluminal brachytherapy boost for a carcinoma of the oesophagus. Material and methods Twenty patients with biopsy-proven carcinoma of the oesophagus received external beam radiotherapy (50 Gy in 25 fractions) with concurrent chemotherapy (cisplatin: 40 mg/m 2 ). After a gap of two to three weeks, intraluminal brachytherapy (10 Gy in two fractions each 1 week apart by a high dose rate 60 Co source) was given. Response was evaluated at 1 month and at 1 year of completion of treatment. In addition, acute and chronic toxicity was evaluated at 1 month and 6 months of treatment. Results Complete response were seen in 80% of patients and partial response in 20% at 1 month. Moreover, there were 65% complete response, 10% local recurrences, 15% patients showed local control with distant metastasis and 10% patients died at 1 year. Grade 1, grade 2 and grade 3 oesophagitis were seen in 10%, 70% and 20% of patients respectively. Stricture was seen in 40% of patients and fistula in 10% of patients. There was no spinal cord, cardiac and nephrotoxicity found. Conclusions With the concept that high tumoricidal dose for adequate tumor control achieved by intraluminal brachytherapy as a mean of dose escalation, while sparing surrounding normal tissue and potentially improving therapeutic ratio, external beam radiotherapy followed by intraluminal brachytherapy could be a better choice for oesophagus carcinoma. [ABSTRACT FROM AUTHOR]

The effectiveness of ionizing radiations for the preservation of cultural heritage (CH) has been recently demonstrated. Although these processes present many advantages with respect to the traditional methods, physico-chemical modifications induced by radiation (namely side effects) represent a concern for CH restorers, archivists and librarians. The present work is focused on the study of the effect of gamma irradiation parameters on the main features of paper. In particular, total absorbed doses up to 10 kGy (commonly suggested for preservation treatments) have been applied, with dose rates ranging from 3 to 10 kGy/h. Different experimental techniques (FTIR, EPR, viscosity and colorimetric analysis) have been used to study the side effects occurrence. The results indicate that the fine-tuning of irradiation condition allow to minimize the unwanted changes, induced by radiation in the treated paper samples. • Gamma radiation at absorbed doses common for preservation of cultural heritage (up to 10 kGy). • Side effects evaluation with several experimental techniques (FTIR, EPR, DP, colorimetric analysis). • Studies were performed at different dose rate values. • Irradiation parameters optimization to minimize the side effects. • Gamma rays represent a suitable and reliable tool for bio-deteriogens elimination purpose. [ABSTRACT FROM AUTHOR]

Abstract: Improvements recently developed at the Nuclear Metrology Laboratory of IPEN-CNEN/SP in São Paulo were performed in order to increase the detector efficiency of a 4πβ−γ coincidence primary system using plastic scintillators in 4π geometry. Measurements were undertaken and compared to the original system and Monte Carlo simulations of the extrapolation curves were calculated for this new system and compared to experimental results. For this purpose, the code Penelope was applied for calculating response functions for each detector and the code Esquema, developed at LMN, was used for simulating the decay scheme processes. [Copyright &y& Elsevier]

• 60Co production in reactor. • Impact of using average power to estimate production. • Radioisotopes production in nuclear reactors. Productions of industrial and medical radioisotopes in operating nuclear reactors have been done for many years. Prior to the implementation, some analyses need to be performed in order to optimize the production of the radioisotopes by putting the targets in appropriate locations in the reactor core. This needs to be done not only to maximize the production of the radioisotopes but also to ensure that the safe operation of the reactor is not jeopardised. In such analyses, an approximation of the average power level is utilized since the actual variation in the power level during the operation of the reactor with the targets inserted in the core is not known. The objective of this paper is to quantify the appropriateness of utilizing an average power during such analyses. Results from the present study indicate that the difference between the estimate and measured 60Co production, which is used as an example of radioisotope produced in a reactor, could be up to around ±2% depending on the flux level using during the irradiation and the duration of the irradiation period. [ABSTRACT FROM AUTHOR]

Using thermoluminiscent dosimeters the absorbed dose in the bladder, rectum and thyroid have been evaluated when 200 cGy was applied to the prostate. The treatment was applied with a 60 Co unit. A water phantom was built and thermoluminiscent dosimeters were located in the position where the prostate, bladder, rectum and thyroid are located. The therapeutic beam was applied in 4 irradiations at 0, 90, 180 and 270° with the prostate at the isocenter. The TLDs readouts were used to evaluate the absorbed dose in each organ. The absorbed doses were used to estimate the effective doses and the probability of developing secondary malignacies in thyroid, rectum and bladder. [ABSTRACT FROM AUTHOR]