Modelling Radiation Doses to Critical Organs of Patients Undergoing Intracavitary Brachytherapy Treatment at Komfo ANOKYE Teaching Hospital

ABSTRACT 

The main aim of radiotherapy is to destroy cancerous tissues with ionizing radiation while the other normal parts of the body are saved or spared. Intracavitary brachytherapy is a procedure in which radioactive sources are placed in the body cavities close to or inside the target volume to deliver radiation at short distances. In this mode of treatment, high radiation dose can be delivered to the tumour volume with rapid dose fall-off into the surrounding normal tissues. In brachytherapy, the dosimetry in biological tissues is a complex process. Dosimetric parameters such as the dose to critical organs and the total dose to the reference points as in the case of Manchester system are critical for patients undergoing intracavitary brachytherapy treatment. In this study, the Finite Element Method (FEM) has been utilized to solve Boltzmann Transport Equation (BTE) to determine the distribution of angular photon fluxes at various positions in the cervix of cancer patients and the dose distribution calculated for the organs of interest. The timedependent linear BTE was used to describe the passage of ionizing radiation taking into account tissue heterogeneities and other scattering phenomena before depositing the absorbed dose in a patient. The simulation was carried out to determine doses to the critical organs, namely the rectum and bladder. Results from the study indicate doses to the rectum and the bladder to be in the range of 10.13-85.67cGy and 21.32-78.81cGy respectively for stage I to stage IV cancer patients. Comparison of the results from the model with data from published articles and dose prescriptions from the treatment planning system of the Radiotherapy Center of the Komfo Anokye Teaching Hospital in Ghana for different cancer stages indicate good agreement with standard error of ±20% to ±34%.