|Year : 2015 | Volume
| Issue : 4 | Page : 151-153
Attenuation of 60Co gamma rays by barium acrylic resin composite shields
Riaz Abdulla1, Mariyam Fidha1, BH Sripathi Rao1, Jagadish Kudkuli2, PD Rekha2, SD Sharma3
1 Department of Oral Pathology and Microbiology, Yenepoya Dental College, Mangalore, India
2 Yenepoya Research Centre, Yenepoya University, Mangalore, India
3 Medical Physics, Radiological Physics, Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India
|Date of Web Publication||11-Feb-2016|
Junior Research Fellow, Yenepoya Research Centre, Yenepoya University, University Road, Deralakatte, Mangalore - 575 018, Karnataka
Source of Support: None, Conflict of Interest: None
Oral squamous cell carcinoma is the sixth most common cancer reported globally, with an annual incidence of over 300,000 cases, of which 62% arise in developing countries. Radiation therapy is a treatment modality that uses ionizing radiation as a therapeutic agent. It is widely employed in the treatment of head and neck cancer, as a primary therapy coupled with surgical procedure and chemotherapy or as a palliative treatment for advanced tumors. However, radiotherapy can cause a series of complications such as xerostomia, mucositis, osteoradionecrosis, and radiation caries. Composite circular disc containing different ratios of acrylic and barium sulfate (BaSO4) were made in-house. The purpose of this study was to evaluate the percentage attenuation from these composite shields in 60 Co gamma rays. A maximum of 8% radiation attenuation was achieved using 1:4 ratio of acrylic-BaSO4 composite shields. The study proposes BaSO4 as one of the compounds in combination with acrylic resin or any other thermoplastic substances for making biocompatible radiation attenuating devices.
Keywords: Acrylic resin, barium sulfate, head and neck cancers, radiation attenuation, radiation caries
|How to cite this article:|
Abdulla R, Fidha M, Sripathi Rao B H, Kudkuli J, Rekha P D, Sharma S D. Attenuation of 60Co gamma rays by barium acrylic resin composite shields. Radiat Prot Environ 2015;38:151-3
|How to cite this URL:|
Abdulla R, Fidha M, Sripathi Rao B H, Kudkuli J, Rekha P D, Sharma S D. Attenuation of 60Co gamma rays by barium acrylic resin composite shields. Radiat Prot Environ [serial online] 2015 [cited 2022 Jul 5];38:151-3. Available from: https://www.rpe.org.in/text.asp?2015/38/4/151/176157
| Introduction|| |
Oral squamous cell carcinoma accounts for more than 90% of all oral cancers and is the most common type of head and neck squamous cell carcinoma causing for about 128,000 deaths worldwide. Three most common fatal cancers affecting Indian men in the age group of 30–69 years are oral (including lip and pharynx), stomach, and lung (including trachea and larynx) cancers. Radiotherapy (RT) plays an important role in the management of patients with head and neck cancers (HNCs). The quality of life post-RT is often drastically reduced due to numerous radiation-induced oral complications including hyposalivation, severe dentition breakdown, associated loss of masticatory function, and various other problems. Radiation therapy is associated with a variety of side effects that vary according to total dosage, rate of radiation delivery, fraction size, field of radiation, radiation source, previous surgical intervention, and individual patient status. Patients may undergo radiation therapy for 3–7 weeks with a total dose ranging from 3000 to >7000 cGy, depending on tumor type and location. In 90–100% of patients whose radiation fields include the oral cavity, some degree of oral complication is expected to develop. Depending on the location of the malignancy, inevitably, the salivary glands, oral mucosa, and jaws have to be included in the radiation treatment portals, resulting in deleterious consequences which affect not only the oral mucosa but also the adjacent salivary glands, bone, dentition, and masticatory musculature and apparatus. The major cause of complications post-RT is due to the scattered radiation received to the adjacent soft and hard tissues.
Lead has been tested as an effective radioprotective material for its use in all radiation shielding garments across healthcare workers in different fields. However, protective gear made of heavy metals is cumbersome to handle and produce more penetrative secondary radiation which require additional shielding, increasing the cost and weight factor. Consequently, research efforts have focused toward designing efficient, lightweight, cost-effective, and flexible shielding materials for protection against radiation encountered. Less hazardous alternatives to lead are titanium, tin, bismuth, barium, or combinations of them. Novel paint designs were examined by dispersing nano tin dioxide and nano tungsten trioxide in epoxy paints, which showed effective attenuation of X-rays and gamma rays. In this study, different compositions of acrylic resin and barium sulfate (BaSO4) were evaluated for radiation attenuation properties.
| Materials and Methods|| |
Preparation of the barium sulfate and acrylic resin composite shield
Hard circular disc plates of 0.5 mm thickness and 100 mm diameter were made by mixing BaSO4 and acrylic resin (powder-liquid combination) in different combination ratios of 1:1, 1:2, 1:3, and 1:4 concentrations. The experimental plates were evaluated with cobalt-60 gamma rays from Bhabhatron-II telecobalt machine of Bhabha Atomic Research Centre (BARC, Mumbai, Maharashtra, India).
Radiation exposure study
The Gafchromic EBT2 film piece (2 cm × 2 cm) was kept at 80 cm distance from the source of telecobalt machine and irradiated for 2 min. Net optical density (R1) of the film was determined using EPSON Expression 10000XL scanner. Another piece of the film was placed at the same distance from the source of telecobalt machine, and the circular disc was put over it. The film was then irradiated for a period of 2 min. Net optical density (R2) of the film was determined using EPSON Expression 10000XL scanner. The ratio (R2/R1) × 100 was calculated and termed as percentage transmission through the disc. The percentage transmission was measured at two different regions of the circular disc for each combination ratio of acrylic resin, BaSO4 mixture. The mean values of percentage transmission through the discs were then calculated, and attenuation values were derived therein.
| Results|| |
[Table 1] presents the mean percentage transmission and mean percentage attenuation by the different barium acrylic composite shields. It is observed that circular disc composed of acrylic resin and BaSO4 in the ratio of 1:4 was found to have maximum percentage attenuation of 8%, as compared to the other combinations. Increasing concentration of BaSO4 in the circular disc resulted in proportionate radiation attenuation, whereas circular discs made exclusively of acrylic resin compound provided minimal attenuating effect.
|Table 1: Mean percentage transmission/attenuation of circular disc in cobalt-60 gamma rays from Bhabhatron--II telecobalt machine|
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| Discussion|| |
Radiation therapy is used in an extensive manner to treat HNCs.
In an effort to reduce the incidence of radiation-induced caries, we attempted to develop a device/devices using biocompatible materials that can be effectively used as an intraoral protection to combat the direct effect of irradiation on teeth. The initial process in this study included the testing of BaSO4 composited with acrylic resins as an effective shield of the oral cavity against radiation caries. Acrylic resins, chemically known as polymethyl methacrylate, are impact modifiers containing at least one dimer fatty acid and/or dimer fatty diol. The composition is suitable for the use to form a sheet or an adhesive, particularly as a pressure sensitive adhesive. They can form complex with themselves upon self-cross-linking or with other compounds owing to their co-cross-linking mechanism. BaSO4 has a density of 4.5 g/cm 3. Although it is lesser when compared with lead (11.34 g/cm 3), BaSO4 composites are found to offer effective shielding similar to lead-based materials. Designing environment-friendly radiation shielding materials were attempted using combinations of tungsten, molybdenum, rubber, and silicon with a BaSO4 base. This composition yielded radiation attenuation properties similar to lead standard and are proven radiation shields. Although BaSO4 is considered as one of the most economic environment-friendly shielding materials, studies have reported it to have some limitations as an independent shielding material because of its low miscibility with other materials. Bilayer barium sulfate–bismuth oxide composite (XPF) thyroid collars have been effectively tested as a lightweight alternative to standard 0.5 mm lead equivalent thyroid collars and have been found to provide superior radiation protection during fluoroscopy-guided interventions. In our study, acrylic resin composited with BaSO4 in the ratios 1:1, 1:2, 1:3, and 1:4 were tested in 1.25 MeV gamma rays from Bhabhatron-II telecobalt machine, and a mean percentage attenuation of 3.6, 5.1, 3.7, and 8.0 was achieved, respectively [Table 1]. Therefore, an increase in the composition of BaSO4 had a comparable higher attenuation effect. The attenuation of a maximum of 8% may not be of great significance in protecting the normal oral structures such as teeth but can be considered a good initial experimental radioprotective initiative. The use of a bismuth sheet and protective aprons made from alloy containing bismuth-tungsten-antimony and a number of shielding materials which were made from composite materials such as bismuth-lead for protection from gamma radiation of 137 Cs,133 Ba, provided 10%, 5%, and 26% reduction in the weight of aprons, respectively, and all of them have the same attenuation compared with lead aprons. Our study also aimed at attaining similar attenuation by testing lead-free materials incorporated in the aprons, in relation to the face and teeth. Here barium was used in combination with acrylic resin compounds to get a composite hard material for radioprotection.
Studies showed that the bismuth shielding significantly decreased the weight of apron, and it was better at reducing the exposure related to lead at all energies within the ranges used. Furthermore, the protective aprons containing alloy (barium-tungsten, and antimony) or the bismuth - lead shielding because of reduction in weight and same attenuation was more efficient than lead apron for wearing in the diagnostic energy ranges.
| Conclusions|| |
Protection of normal structures such as teeth, oral mucosa, and other dentofacial structures during radiation therapy are becoming an essential part of treatment regime in the HNC patients. This study showed that efficacy of barium-acrylic combination was minimal in bringing about radiation attenuation. Therefore, emphasis should be laid on using BaSO4 compound to effectuate proportional radiation attenuation with increasing concentration. Other materials such as lead, barium, bismuth, titanium, tungsten, tin, and alloys of their combination can also be tested for better attenuation. This will prove a better quality of post-RT life for the patients undergoing treatment for HNCs.
We would like to extend our sincere gratitude towards the Board of Research in Nuclear Sciences (BRNS), Department of Atomic Energy (DAE), Government of India (Grant No- 34(1)/14/36/2014 BRNS). We are grateful to the BARC Mumbai for their support in the study.
Financial support and sponsorship
This study is funded by Board of Research in Nuclear Sciences (BRNS), Department of Atomic Energy, Government of India (Grant Number 34(1)/14/36/2014 BRNS).
Conflicts of interest
There are no conflicts of interest.
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