Abstract: Radiation therapy is currently employed in managing approximately 50% of cancer patients worldwide with the aim of controlling the tumour without incurring unacceptable harm to surrounding normal tissue. It is recommended that the dose delivered to the patient be monitored with a dosimeter as part of quality assurance (QA) procedure. This however is not the case in a number of institutions, including the Oncology Unit of Ghana. Hence there is the need to perform in vivo dosimetry to check accuracy of actual absorbed dose delivered to the patient.
The study was aimed at performing in-vivo entrance dose dosimetry using thermo-luminescent dosimeters (TLDs) to verify the accuracy of the radiation delivered to patients as compared to prescribed doses.
An experimental study design, using a convenience sampling method, was used to conduct a study with 14 patients undergoing radiotherapy for cancers of the head and neck, spinal, pelvic and breast regions at the study site. A water phantom calibration was done using the recommended IAEA method. Calibration coefficients were determined with TLDs, using a Perspex phantom to derive correction factors. Patients’ doses were measured with TLDs during treatment.
The findings of the study showed that radiation dose administered to patients increased with field size but decreased with depth as established in literature. The highest frequency of percentage errors occurred between the interval of 4-4.99% and the lowest within the 5-5.99% interval. Also, the mean absolute percentage error of the measured doses from the prescribed doses was 3.01% with a standard deviation of 1.59%.
Radiation doses delivered to patients were acceptable within the recommended tolerance level of ±5%. This demonstrates the importance of in-vivo dosimetry in verifying the absorbed dose received by patients during radiotherapy.
Keywords: Absorbed dose, Entrance dose, Radiotherapy, Perspex phantom.
Title: In-Vivo Dosimetry Using Thermo-Luminescent Dosimeters in a Cobalt-60 Beam In a Developing Country
Author: Samuel Y. Opoku, Kofi Adesi Kyei, Joel Yarney, Pearl Lawson, Samuel N. A. Tagoe, Eric K. T. Addison
International Journal of Healthcare Sciences
ISSN 2348-5728 (Online)
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