A description is given of the numerical integration method for the calculation of the mean kidney dose for a Co-57 external radiation source. Based on this theory, a computer program was written. Initial calculation of the kidney volume shows that the method has a good accuracy. For the mean kidney dose, this method gives a satisfactory result, since the calculated value lies within the acceptable range of the central axis depth dose.
Satu huraian diberikan tentang kaedah pengkamiran berangka untuk mengira dos buah pinggang purata untuk satu sumber sinaran luar Co-57. Berdasarkan teori ini, satu program komputer ditulis. Pengiraan awal isipadu buah pinggang menunjukkan yang kaedah ini mempunyai ketepatan yang baik. Untuk dos buah pinggang purata, kaedah ini memberikan keputusan yang baik, kerana nilai kiraan terletak diantara julat dos kedalaman paksi pusat yang diterima.
IAEA in its publication year 2000 has recommended a worksheet for the determination of absorbed dose to water in an electron beam. We evaluated the worksheet via an absorbed dose to water determination work at a local radiotherapy center using a 12 MeV electron beam. We found that if several modifications are made, this IAEA worksheet will become more user-friendly and could facilitate and fasten the process of quality assurance audit. The modifications are given and discussed.
[IAEA dalam penerbitannya tahun 2000 telah mengesyorkan satu helaian kerja untuk menentukan dos terserap kepada air dalam alur electron. Helaian kerja ini dinilai melalui satu kerja penentuan dos terserap kepada air di satu Pusat radioterapi tempatan menggunakan satu alur electron 12 MeV. Sekiranya beberapa pengubahsuai dibuat, helaian kerja IAEA ini akan menjadi lebih mesra pengguna dan dapat mempermudahkan dan mempercepatkan lagi proses audit jaminan kualiti. Pengubahsuaian ini diberikan dan dibincangkan].
This note describes a method for the determination of the peak-to-total ratio, P/T versus gamma-ray energy of range 59.54-1836.03 keV of a HPGe detector. Results show that this ratio decreases with energy. To check the validity of these results, two approaches of results comparison, namely with the ratio reported by Cesana and Terrani in year 1989 and with the shape of total efficiency reported by Debertin and Helmer in year 1988 were taken. lt is shown that this method gives satisfactory results since the obtained values of P/T and the shape of the total efficiency curve were in good agreement with the reported works. The precautional step that need to be taken when dealing with energy 59.54 keV 241Am source and the reason for taking the total efficiency as the evaluation tool are given.
Two important parameters for utilizing Ko-standardization method namely, absolute peak efficiency at reference position and peak-to-total ratio at different geometrical positions using standard point sources and HPGe were experimentally determined. Coincidence correction factor, C, for reference position and certain nuclides were also calculated and all almost equal to one. The importance and implication of this work to the K0-standardization method are presented. Other essential nuclear parameters which have to be experimentally determined or obtained from literature are also presented.
Dua parameter untuk kegunaan kaedah pemiawaian K0 iaitu kecekapan puncak absolut pada kedudukan rujukan dan nisbah jumlah-ke-puncak pada berbagai kedudukan geometri telah ditentukan secara eksperimen. Punca titik piawai dan HPGe digunakan. Faktor pembetulan koinsiden, C, yang digunakan untuk kedudukan piawai dan beberapa nuklid telah dihitung dan semuanya mempunyai nilai hampir sama dengan satu. Kepentingan dan implikasi kerja ini kepada kaedah pemiawaian K0 dikemukakan. Parameter nuklear lain yang ditentukan secara eksperimen atau yang diperolehi daripada pustaka juga dibentangkan.
This research reports the annual effective dose of dwellers based on the finding of natural radioactivity concentrations in
Malaysian tiles. A total of 30 tiles samples obtained from the manufacturer or bought directly from local hardware store.
Natural radioactivity was analyzed using gamma spectrometry system for 12 h counting times. The activity concentration
of 226Ra, 232Th, and 40K in the analyzed samples ranged from 37.50 – 158.05 Bq kg-1, 42.22 – 80.19 Bq kg-1 and 349.46 –
750.18 Bq kg-1, respectively. The determined radium equivalent activity was below than the recommended limit of 370
Bq kg-1. The external dose received by dwellers due to natural radionuclides in tiles were projected for 1, 5, 10, 20 and
50 years through six exposure pathways using Resrad-build computer code. The results showed that the annual effective
dose received by dwellers increased for the investigated timelines but still lower than the annual recommended limit of
1500 µSv. The simulation result also indicates that radon gas was the primary radiation exposure which contributes
80-94 % from the total radiation exposure to dwellers.
Heel Effect is the well known phenomena in x-ray production. It contributes the effect to image
formation and as well as scattered radiation. But there is paucity in the study related to heel effect.
This study is for mapping and profiling the dose on the surface of water phantom by using mobile
C-arm unit Toshiba SXT-1000A. Based on the result the dose profile is increasing up to at least
about 57% from anode to cathode bound of the irradiated area. This result and information can be
used as a guide to manipulate this phenomenon for better image quality and radiation safety for
this specific and dedicated fluoroscopy unit.