Authors Hanouf H. Alghanmi Biophysics Research Group, Physics Department, Faculty of Science, Mansoura University, Mansoura, Egypt; Department of Radiation Oncology, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Jeddah, 21423, Saudi Arabia. E.M. Abdelrazek Physics Department, Faculty of Science, Mansoura University, Mansoura, Egypt. Ehab Attalla National Cancer Institute, Cairo University, Giza, Egypt. Mazen Al Gaoud Department of Radiation Oncology, King Abdullah Medical City, Jeddah, Saudi Arabia. Nasser Al Dhaibani Department of Radiation Oncology, King Abdullah Medical City, Jeddah, Saudi Arabia Hosam Salaheldin Biophysics Research Group, Physics Department, Faculty of Science, Mansoura University, Mansoura, Egypt DOI: https://doi.org/10.22317/jcms.v11i5.1982 Abstract

Objectives: This study aims to perform a dosimetric and radiobiological comparison between Three-Dimensional Conformal Radiotherapy (3DCRT) and Intensity-Modulated Radiotherapy (IMRT) for a hypofractionated regimen.

Methods: A retrospective analysis was conducted on fifty patients with left-sided, node-negative breast cancer after breast-conserving surgery. Treatment plans were generated for each patient using both 3DCRT (field-in-field technique) and IMRT (inverse-planned with 5 fields) techniques for a prescription dose of 40.05 Gy in 15 fractions. Plans were evaluated based on dosimetric parameters for planning target volume (PTV) coverage (Dmin, Dmean, V95%, V105%), conformity (CI), homogeneity (HI), and doses to OARs (heart, lungs, spinal cord). Radiobiological evaluation included calculating Tumor Control Probability (TCP) and Normal Tissue Complication Probability (NTCP).

Results: IMRT demonstrated significantly superior PTV coverage, with higher Dmin (27.55 vs. 16.54 Gy, p<0.0001), V95% (99.81% vs. 87.55%, p<0.0001), and ideal conformity (CI=1.00 vs. 0.87, p<0.0001). However, IMRT resulted in a larger volume receiving 105% of the dose (V105%=44.68% vs. 11.70%, p<0.0001). For OARs, IMRT reduced the mean heart dose (3.40 vs. 2.51 Gy, p<0.0001) and ipsilateral lung V20Gy (17.42% vs. 18.21%, p=0.31), but increased low-dose exposure (e.g., heart V10Gy and lung V5Gy). IMRT demonstrated a superior TCP (96.2% compared to 93.1%, p<0.0001) and IMRT demonstrated a superior TCP (96.2% compared to 93.1%, p<0.0001) and markedly reduced NTCP for radiation pneumonitis (2.1% versus 19.2%, p<0.0001) and cardiac problems (0.10% versus 0.20%, p<0.0001). NTCP for radiation pneumonitis (2.1% versus 19.2%, p<0.0001) and cardiac problems (0.10% versus 0.20%, p<0.0001). IMRT required substantially more monitor units and longer beam-on time.

Conclusion: IMRT offers a dosimetrically and radiobiologically enhanced plan for hypofractionated radiation treatment of left-sided breast cancer, ensuring superior target coverage and a marked decrease in the anticipated risk of pulmonary and cardiac problems. Nonetheless, this strategy incurs the expense of heightened low-dose exposure to adjacent tissues and increased complexity in treatment administration. The selected approach must be tailored according to patient anatomy and specific risk profiles.

How to Cite

Alghanmi , H. H., Abdelrazek, E., Attalla, E., Al Gaoud, M., Al Dhaibani, N., & Salaheldin, H. (2025). Dosimetric and Radiobiological Comparison of IMRT Versus 3DCRT Treatment Plans for Hypofractionated Left-Sided Breast 10 MV Photon Irradiation: A Single Center Study . Journal of Contemporary Medical Sciences, 11(5). https://doi.org/10.22317/jcms.v11i5.1982