- - - PhD Candidate, Department of Physics, M.J.P. Rohilkhand University, Bareilly Uttar Pradesh, India
- - - PhD, Government Cancer Hospital, Mahatma Gandhi Memorial Medical College, Indore-۴۵۲۰۰۱, India
- - - PhD, Department of Applied Science & Humanities, Dr. A.P.J Abdul Kalam Technical University, Lucknow, India
- - - PhD, Department of Physics Bareilly College Bareilly, Uttar Pradesh, India
- - - MSc, Apollomedics Hospital, Lucknow, India
- - - PhD, Department of Radiation Oncology, Ram Manohar Lohia Medical sciences Lucknow, India
- - - MD, Medical Physics Division & amp Department of Radiation Oncology, Apollomedics Hospital, Lucknow, India

Background: Modern radiotherapy techniques are using advanced algorithms; however, phantoms used for quality assurance have homogeneous density; accordingly, the development of heterogeneous phantom mimicking human body sites is imperative to examine variation between planned and delivered doses. Objective: This study aimed to analyze the accuracy of planned dose by different algorithms using indigenously developed heterogeneous thoracic phantom (HT). Material and Methods: In this experimental study, computed tomography (CT) of HT was done, and the density of different parts was measured. The plan was generated on CT images of HCP with ۶ and ۱۵ Megavoltage (MV) photon beams using different treatment techniques, including three-dimensional conformal radiotherapy (۳D-CRT), intensity-modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT). Plans were delivered by the linear accelerator, and the dose was measured using the ion chamber (IC) placed in HT; planned and measured doses were compared. Results: Density patterns for different parts of the fabricated phantom, including rib, spine, scapula, lung, chest wall, and heart were ۱.۸۴۹, ۱.۹۷۶, ۱.۹۸۳, ۰.۱۷۳, ۰.۸۵۵, and ۰.۸۳۳ g/cc, respectively. Variation between planned and IC estimated doses with the tolerance (±۵%) for all photon energies using different techniques. Acuros-XB (AXB) showed a slightly higher variation between computed and IC estimated doses using HCP compared to the analytical anisotropic algorithm (AAA). Conclusion: The indigenous heterogeneous phantom can accurately simulate the dosimetric scenario for different algorithms (AXB or AAA) and be also utilized for routine patient-specific QA.

Algorithms, Computed Tomography, Human body, Lung Phantoms, Volumetric-Modulated Arc Therapy, Ribs