Comparison Of Treatment Indices Between Telecobalt Machine And Linear Accelerator-Based Treatment Plans For Selected Conformal Radiotherapy Cases

ABSTRACT

The use of telecobalt machine in radiotherapy is of concern in developing countries where there is a limited resource. As such, the study was to ascertain if telecobalt (cobalt60) machine could be feasible to generate and deliver treatment plans with optimal treatment indices comparable to those of a linear accelerator (Linac). Retrospective DICOM-Radiotherapy images of patients earmarked for treatment of breast, prostate and lung cancer obtained from the European Society for Radiotherapy and Oncology (ESTRO) were uploaded unto the treatment planning system (TPS) used by National Center for Radiotherapy and Nuclear Medicine (NCRNM) and Sweden Ghana Medical Center (SGMC Cancer Center). Based on departmental protocol, international dose constraints, careful selection and adjustments of beam parameters, treatment plans were generated and delivered. Thereafter, treatment indices were calculated and compared. The plans were also subjected to quality assurance to determine their adequacy for clinical implementation. The results of conformity index (CI) were: breast (0.9705, 0.9303), prostate (0.9881, 0.9948), lung (0.9604, 1.0005) and for homogeneity index (HI) were: breast (1.1452, 1.0910), prostate (1.0226, 1.0141), lung (1.0960, 1.0682) between cobalt-60-based and linac- based treatment plans respectively. Analysis of the treatment indices has shown telecobalt dose conformities and homogeneities to be comparable to those of linac-based despite having higher doses to organ at risk. The end to end test showed a deviation of 1.5% and 0.83% with a tolerance of between cobalt-60 machine and linac while verification of planned and delivered dose in anthropomorphic phantom showed a deviation of 0.5% and 0% with a tolerance of between cobalt-60-based plan and linac-based plan respectively. Hence, both machines were performing according to the calibrated dataset within the tolerance level. Therefore, in situations of inadequate financial capacity and maintenance associated with linear accelerators, the use of telecobalt machines should be encouraged for the benefit of the patients.