An Evaluation of the Effectiveness of the Structural Radiation Shielding
Barriers of a Radiation Therapy Facility: Cancer Institute of Guyana
Parmeshwarie Seodat
2
, Petal P Surujpaul
1*
and Deivis Errada
2
1
Department of Radiology, Medical Physicist at Georgetown Public Hospital Corporation, University of Guyana, Guyana
2
Medical Physicist at Cancer Institute of Guyana, University of Guyana, Guyana
*
Corresponding author: PP Surujpaul, Department of Radiology, Medical Physicist at Georgetown Public Hospital Corporation, East & Thomas Streets, North
Cummingsburg, Georgetown, Georgetown, Demerara 00000, University of Guyana, Guyana, Tel: +1592-650-076; E-mail: psurujpaul@gmail.com
Received date: Feb 09, 2018; Accepted date: Feb 22, 2018; Published date: Feb 27, 2018
Copyright: © 2017 Seodat P, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original author and source are credited.
Abstract
This project thoroughly investigates the integrity of the structural radiation shielding barriers of the radiation
therapy facility of Cancer Institute of Guyana which houses a Linear Accelerator (LINAC) of 6 MV. The LINAC
comprises a retractable beam stopper which renders all barriers of the bunker as secondary. However, the barriers
that receive the primary incidence of the beam at the gantry angles 900 and 2700, Walls A and B, have been
annotated as primary. In addition, for the other barriers, a phantom was used in making measurements for scatter.
The bunker at Cancer Institute has been in existence since 2006. Therefore, the primary aim of this study is to
validate the effectiveness of the structural radiation barriers of the radiation therapy facility through measurements
and computations of the Instantaneous, Time Averaged and Weekly Dose Rates of the barriers and calculations of
the attenuation coefficients using the Tenth value layer of the existing shielding material, concrete. The results
gathered serve as a basis for comparative analysis to the Institute’s Commissioning Report and the International
Standards. The Instantaneous measurements were recorded using the Fluke Biomedical Ionization Chamber.
The results of the project annotate that the radiation shielding barriers at Cancer Institute of Guyana are very
effective. The instantaneous dose rates recorded by the ionization chamber of the existing barriers were significantly
lower than those calculated. The time averaged and weekly dose rates were very low as well. Scattered radiation
measured conformed with the international standard of being less than 0.1% of the primary beam. However,
calculations for barrier thicknesses required were higher than the existing barrier thicknesses. This was as a result of
the field size parameter of the LINAC being utilized at its maximum. Nevertheless, these verifications of the
effectiveness of the radiation shielding barriers were in conformity to the stipulated standards and well below
calculated outcomes.
Keywords Radiotherapy; TLD; Ionizing radiation; Dose; (OEP)
Occupationally exposed personnel
Introduction
Cancer Institute of Guyana (CIG) is a multi-modality imaging
facility that has been operational since 2006. Tis Institution sits on the
coastal belt in the capital city of Georgetown, at the corner of Lamaha
and East streets, and to the East-north eastern side of the Georgetown
Public Hospital Corporation (~1.16 km from the Atlantic Ocean) [1].
Interiorly, all ionizing radiation modalities are located from the
western to southern sides of the building while the non-ionizing
departments are housed on the eastern side. Te ionizing radiation
modalities include computed tomography, mammography and x-ray
(on the western side) and radiotherapy (with linear accelerator with an
energy of 6 MV for photons and a range of energies for electron beams
from 5,7,8,10,12 and 14 MeV) to the southern end of the building.
Non-ionizing services ofered include ultrasonography, chemotherapy
and medical consultancy/gynecology [2].
Seeing that the occupancy factor (T) on the western side of the
building housing the ionizing radiation modalities is high (where
T=1), primary structural shielding barriers have been incorporated.
Te purpose of this incorporation is to reduce the amount of
unnecessary ionizing radiation exposure to members of the public,
patients and occupationally exposed personnel whose annual dose
limits are 1 mSv and 20 mSv, respectively [3].
At Cancer Institute of Guyana, the linear accelerator has a
retractable beam-stopper or beam-shield that acts as a primary barrier,
since the average transmission of the beam-stopper does not exceed
0.1% of the primary beam. Terefore, it is safe to say that the radiation
therapy bunker has no primary barriers; all barriers are considered
secondary [4].
Tis project seeks to evaluate the efectiveness of the radiation
shielding of the radiation therapy department of the facility by means
of weekly and instantaneous dose rate measurements. Tese will be
done with the utilization of an ionization chamber.
In addition, the project also encompasses comparisons of the
structural shielding from the time of commissioning of the machinery
to present day; in an efort to assess the impacts of these changes (in
equipment) on the structural shielding barriers of the facility [5].
Together with that, the researcher aims at assessing the attenuation
coefcients of each shielding barrier, via the tenth value layer of the
existing shielding material of the barriers (concrete) and making an
overall comparison of the results gained from these existing
measurements to the international standards governing radiation
protection in radiotherapy [6].
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ISSN: 2168-9784
Journal of Medical Diagnostic
Methods
Seodat et al., J Med Diagn Meth 2018, 7:1
DOI: 10.4172/2168-9784.1000265
Research Article Open Access
J Med Diagn Meth, an open access journal
ISSN:2168-9784
Volume 7 • Issue 1 • 1000265