Analytic radiography is a normal image testing technique which has been utilized for quite a long time. It is recommended by specialists so they can identify any problem in patients' bodies without a cut. Thinking about its wide use, the principle objective of this investigation is to give a top notch picture by keeping the radiation portion as low as conceivable through identifying any variety in quality control (QC) boundaries. In this work, some standard quality control boundaries, for example, voltage exactness, time precision test, tube yield linearity, half value layer (HVL) of x-beam were measured. These quality control (QC) boundaries were estimated by a dosimeter keeping a distance of 100 cm from source. The voltage precision went from 0.31% to 4.67% and the time exactness test went from 0% to 2.29%. The consequences of this investigation show that all the QC boundaries are inside the acceptable level which guarantees the advancement of the low portion conveyed to the patients.
The volumetric effect occupied by the air cavity for the dosimetry of high energy photon beam is impossible to ignore using standard ionization chambers. Hence, the dose measurement should be corrected with a displacement perturbation correction factor (P dis ) or using an Effective Point of Measurement (EPOM). The aim of this study was to calculate the EPOM of some ionization chambers and evaluation of the shift of EPOM that recommended by various international protocols under both reference and non-reference condition. The work was performed with Percentage Depth Dose (PDD) curves by placing chambers (PTW 30013, FC 65G and Semiflex 31010) at the geometrical centers for field size(s) of 5cm × 5cm to 30cm × 30cm at 100cm Source to Surface Distance (SSD) for photon energy 6, 10 and 15MV respectively. The shift of the cylindrical chambers also estimated from PDD values in comparison with reference PDD values by Parallel Plate Chamber (PPC 40 and Murkus 23343) of 100%, 80% and 50% depth in the water. The present study shows that the effective shift is not only varies with chamber materials but also with photon energy. On the other hand the periodical calibration factor of some ionization chambers at standard procedures were compared with manufacturer values also varies with time which is an important issues for the precisional dosimetry in radiotherapy. The details of the EPOM and chamber calibration factor is discussed.
The absorbed dose-to-water calibration coefficients ND,W of some ionization chambers were determined in terms of the secondary standard chambers in 60Co gamma-ray beam based on the TRS-398 protocol. The reference absorbed dose-to-water Dw were measured using secondary standard ionization chambers of model NE 2781#0537 (0.60 cm3 volume) and NE 2771#1205 (0.69 cm3 volume) which are traceable to the dosimetry laboratory of the International Atomic Energy Agency (IAEA). This study mainly focuses on the comparative assessment of the determined ND,W coefficients of twenty cylindrical ionization chambers from various user groups. The determined ND,W coefficients were compared with the manufacturer provided ND,W coefficients. The observed percentage of deviation between the measured and the manufacturer’s ND,W coefficients among all the chambers were found to be in the range of 0.019% and -2.263% as the least and highest, respectively. The observed percentage of deviations for studied chambers were found within the IAEA’s acceptance limit of 1.5% with an exception for three chambers. This observed discrepancy with the IAEA’s acceptance limit for the three chambers out of the twenty chambers, indicates the calibration necessity before using chambers in routine reference dosimetry. In ND,W measurement, the uncertainty Uc is reported with the coverage factor k=1 that providing a level of confidence of approximately 68%.
Modern radiotherapy facilities like 3-Dimensional conformal radio therapy (3DCRT), Intensity Modulated Radiotherapy (IMRT), were recently suggested in Co-60 machine with Multi-leaf Collimator (MLC). In this study, two reference chambers NE-2571#1205 and NE2581#537 were used for absolute dose measurement in Equinox accelerator. A comparison of dose measurement by two different IAEA protocols TRS-277 and TRS-398 has been studied. Analyzing TRS-398, a common shaped empirical formula was developed for the four Co-60 units of four Medical Colleges in Bangladesh with fitting parameters. It was found that an average discrepancy in the determination of absorbed dose in water among the two different protocols TRS-277 and TRS-398 were 1.33 % for the chamber NE-2571#1205 and 0.65 % for the chamber NE2581#537 with combined uncertainty ±1.59 % (k=1). A good convergence has been obtained in the concepts and methods in this study.
Along with the high-quality image, the enormous observance of CT in medical diagnosis delivers radiation doses to patients that are alarmingly higher than other modalities. Observance of entrance doses of patients undergoing selected diagnostic CT in Bangladesh, calculations of Effective Dose (ED) to analyze ED distribution and to determine the whole-body effect of exposure were carried out on Alderson Rando male human phantom maintaining IAEA TRS 457 protocols. Entrance doses of different organs were observed using IBA Kermax plus Tino DDP and pocket dosimeters. Corresponding specific ED (by conversion coefficient) and whole-body ED (by tissue weighting factor) were estimated from it. ED CC found in this study has a wide range from 0.30 to 395.00 µSv for Head, 12.75 to 1075.00 µSv for Chest, 7.35 to 2578.80 µSv for abdomen and 2.40 to 3320 µSv for Gonad. EDwhole was calculated and further used to estimate risk factor and incident per population. Cancer risks estimated by risk calculator were found higher for chest and abdomen CT respectively 2.59×10 -2 (1:3854) and 4.45×10 -2 (1:2246) at the age of 25 and due to having double exposure. The results were compared with established international reference dose levels and found below reference dose levels.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.