A four-rod type heavy-ion radio frequency quadrupole (RFQ) linac has been designed, constructed, and tested for the rare ion beam (RIB) facility project at VECC. Designed for cw operation, this RFQ is the first postaccelerator in the RIB beam line. It will accelerate A/q < or = 14 heavy ions coming from the ion source to the energy of around 100 keV/u for subsequent acceleration in a number of Interdigital H-Linac. Operating at a resonance frequency of 37.83 MHz, maximum intervane voltage of around 54 kV will be needed to achieve the final energy over a vane length of 3.12 m for a power loss of 35 kW. In the first beam tests, transmission efficiency of about 90% was measured at the QQ focus after the RFQ for O(5+) beam. In this article the design of the RFQ including the effect of vane modulation on the rf characteristics and results of beam tests will be presented.
The International Commission of Radiological Units (ICRU) sets a tolerance of ±5 % on dose delivery, with more recent data limiting the overall tolerances to ±3 %. One of the best methods for accurate dose delivery and quality check is in vivo dosimetry, while radiotherapy is performed. The present study was carried out to test the applicability of diodes for performing in vivo entrance dose measurements in external photon beam radiotherapy for pelvic tumours and its implementation as quality assurance tool in radiotherapy. During November 2007 to December 2009, in 300 patients who received pelvic radiotherapy on a multileaf-collimator-assisted linear accelerator, the central axis dose was measured by in vivo dosimetry by p-Si diodes. Entrance dose measurements were taken by diodes and were compared with the prescribed dose. Totally 1000 calculations were performed. The mean and standard deviation between measured and prescribed dose was 1.26 ± 2.8 %. In 938 measurements (93.8 %), the deviation was <5 % (1.36 ± 2.9%); in 62 measurements (6.2 %) the mean deviation was >5 % (5.51 ± 2.3 %). Larger variations were seen in lateral and oblique fields more than anteroposterior fields. For larger deviations, patients and diode positional errors were found to be the common factors alone or in combination with other factors. After additional corrections, repeated measurements were achieved within tolerance levels. This study showed that diode-detector-based in vivo dosimetry was simple, cost-effective, provides quick results and can serve as a useful quality assurance tool in radiotherapy. The data acquired in the present study can be used for evaluating output calibration of therapy machine, precision of calculations, effectiveness of treatment plan and patient setup.
Background: Carcinoma of oral tongue has a great potential for metastatic spread to neck nodes, which may not be clinically detected in early stage. To detect frequency of occult neck metastasis in clinically No patients with early oral tongue carcinoma (stage I & II) the study has done. Methods: It was a 2 years cross sectional study among fifty patients in three tertiary care hospitals of Dhaka from 2016 to 2018. Results: Majority of the patients were male (M:F=3:2) with age ranged 25 to 80 years. Among these patients 38(76%) were in T1 and remaining 12(24%) in T2 stage. Tongue ulceration was most common(84%) presenting feature followed by dysphagia(64%) and pain(52%).Only 32(64%) patients revealed no histopathological proved metastasis(true N0). Occult nodal metastasis was significantly common(83.33%) among male patients than females(p<0.01) and also common(72.22%) among < 50 years age group(p<0.01).Sampling node positive was significantly more(66.67%) in T2 stage(p<0.01). Conclusion: Regarding clinical, radiological and histopathological stages and stage migration of early carcinoma in oral tongue this study revealed significant differentiation among these methods. This study implies sampling neck dissection of sentinel neck nodes in early oral tongue carcinoma for management. Bangladesh J Otorhinolaryngol; October 2020; 26(2): 147-152
Purpose: Recent studies have shown increased prostate cancer control rates with radiation dose escalation. Herein the experience of dose escalation by high dose rate brachytherapy (HDR-BT) adjunct to the three-dimensional conformal radiation therapy (3D-CRT) for prostate cancer is presented. Patients and methods: During the period between August 2005 and July 2007, patients with intermediate and high risk prostate cancer were treated with 3D-CRT of dose 46Gy ‚ 23 fractions to whole pelvis followed by: Arm A (102 patients): prostate boost with HDR-BT 14 Gy · 2 sessions and Arm B (103 patients): prostate boost via 3D-CRT of dose 26 Gy ‚ 13 fractions. Primary objectives were overall survival (OS), distant metastases free survival (DMFS) and PSA progression free survival (PPFS) rates. Secondary objectives were the toxicity profile and post-radiation histopathological response.Results: At median follow up of 3.5 years, PPFS, DMFS and OS rates were; 97.8% versus 89.0% (p = 0.009), 98.1% versus 93.6% (p = 0.13) and 98.8% versus 91.6% (p = 0.24) in Arm A and Arm B. respectively. Grade 3 or 4 delayed genitourinary toxicities occurred in 2% and 4.8% of patients in Arm A and Arm B, respectively. Delayed grade 3 and 4 gastrointestinal toxicities were seen in 2% and 3.9% of patients in Arm A and Arm B, respectively. The post-radiation prostate biopsies were negative in 14/17(82.3%) and 9/15 (60%) in Arm A and Arm B, respectively.Conclusion: 3D-CRT combined with HDR-BT resulted in better PPFS and lower morbidity than 3DCRT alone for intermediate and high risk prostate cancer.
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