Dosimetry Evaluation of Treatment Planning Systems in Patient-Specific ۳D Printed Anthropomorphic Phantom for Breast Cancer after Mastectomy using a Single-Beam ۳D-CRT Technique for Megavoltage Electron Radiation Therapy

Background: The patient-specific ۳D printed anthropomorphic phantom is used for breast cancer after mastectomy developed by the laboratory of medical physics and biophysics, Department of Physics, Institut Teknologi Sepuluh Nopember, Indonesia. This phantom is applied to simulate and measure the radiation interactions occurring in the human body either using the treatment planning system (TPS) or direct measurement with external beam therapy (EBT) ۳ film.Objective: This study aimed to provide dose measurements in the patient-specific ۳D printed anthropomorphic phantom using a TPS and direct measurements using single-beam three-dimensional conformal radiation therapy (۳DCRT) technique with electron energy of ۶ MeV.Material and Methods: In this experimental study, the patient-specific ۳D printed anthropomorphic phantom was used for post-mastectomy radiation therapy. TPS on the phantom was conducted using a ۳D-CRT technique with RayPlan ۹A software. The single-beam radiation was delivered to the phantom with an angle perpendicular to the breast plane at ۳۳۷.۳° at ۶ MeV with a total prescribed dose of ۵۰۰۰ cGy/۲۵ fractions with ۲۰۰ cGy per fraction.Results: The doses at planning target volume (PTV) and right lung confirmed a non-significant difference both for TPS and direct measurement with P-values of ۰.۰۷۴ and ۰.۱۴۳, respectively. The dose at the spinal cord showed statistically significant differences with a P-value of ۰.۰۰۲. The result presented a similar skin dose value using either TPS or direct measurement. Conclusion: The patient-specific ۳D printed anthropomorphic phantom for breast cancer after mastectomy on the right side has good potential as an alternative to the evaluation of dosimetry for radiation therapy.