Physical and Radiobiological Evaluation of Gamma Knife Radiosurgery Plans in the Treatment of Meningioma: Comparison between two isodose lines (50% and 75%)

Elbaz‬, ‪Gad Yahia; Hendam, Hedaya Mohammed; Alashkar, ElSayed Mohammed; tohamy, Khairy Mohammed; Attalla, Ehab Marouf

doi:10.21608/ejbbe.2022.107953.1052

	Physical and Radiobiological Evaluation of Gamma Knife Radiosurgery Plans in the Treatment of Meningioma: Comparison between two isodose lines (50% and 75%)
Egyptian Journal of Biomedical Engineering and Biophysics
Article 2, Volume 23, Issue 1, 2022, Page 11-25 PDF (1 MB)
Document Type: Original Article
DOI: 10.21608/ejbbe.2022.107953.1052
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Authors
‪Gad Yahia Elbaz‬ ¹; Hedaya Mohammed Hendam ²; ElSayed Mohammed Alashkar ³; Khairy Mohammed tohamy ⁴; Ehab Marouf Attalla ⁵
¹faculty of Science -Al-Azhar University
²Assistant professor of neurosurgery at Gamma knife Damietta Center, Department of Neurosurgery, faculty of medicine, Damietta Al-Azhar university Hospital. Cairo, Egypt.
³Lecture of medical physics at Biophysics Branch, Physics Department, Faculty of Science, Cairo Al-Azhar University. Cairo, Egypt.
⁴physics department,Faculty of Science, Al-Azhar University, Cairo, Egypt
⁵Professor of medical physics at National Cancer Institute, Cairo University. Cairo, Egypt.
Abstract
This work explores how the choice of prescription isodose line (IDL) achieves a high probability of local tumor control (Tumor Control Probability, TCP) at low risk of normal tissue complications (Normal Tissue Complications Probability, NTCP) for Gamma Knife Radiosurgery at two different plans applying different isodose lines to evaluate the radiosurgical metrics, plan quality, and outcome probability in treatment of meningioma using Gamma Knife Radiosurgery (GKS). METHODS: The cross-sectional study included 10 patients (4 male and 6 female) with median age of 42 years (21-66) and presented with radiologically diagnosed meningioma. Two radiosurgical forward plans were applied with same marginal dose of 12Gy at two different isodose lines of 50% and 75% isodose alternatively using Leksell Gamma Plan of single session GKS. A quantitative approach has been conducted to evaluate and compare both plans. Dose-volume histogram was imported to MATLAB to compute tumor control probability (TCP), normal tissue complications probability (NTCP) values at 5 years for each plan, and physical indices such as coverage, selectivity, conformity, heterogeneity, and gradient indices. RESULTS: Median target irradiated volume was 5.44 cm3(0.59-23.72). TCP was significantly higher in the plan using 50% isodose line for the marginal dose than that using 75% isodose line (94.98%, 45.09%, p=0.0018, Mann-Whitney test). Brainstem and optic apparatus NTCPs were very low with median of 0.01% (0-0.03%) in the former plan and zero in the later one (p=0.005, Mann-Whitney test). CONCLUSION: Radiobiological models and physical indices could be used for the optimum plan selection of GKS.
Keywords
Leksell Gamma Plan; Dose Volume Histogram; Tumor Control Probability; Normal tissue complication Probability; Physical indices


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