Clinical target volume to planning target volume margin assessment for different radiotherapy treatment sites based on the patient set-up errors using electronic portal image device

Abstract

Author(s): Mohamed Elsharkawy*, Yasser Rashed, Nasser Abdelbary, Abd El-Azim A. Hussein and A. El-Sersy

Purpose: The purpose of this study was to calculate the Clinical Target Volume (CTV) to Planning Target Volume (PTV) margin as a result of patients’ setup errors of different treatment sites using Electronic Portal Imaging Device (EPID). Methods: Brain, head and neck, breast, lung, bladder, rectum, and prostate were each represented by 30 individuals in this research, for a total of 210 patients. During radiation treatment, set-up errors were measured and collected. The necessary facts were collected to determine the optimal margin for each location to transition from CTV to PTV. Results: The setup errors of thirty brain patients varied between 0.0 and 5.0 mm, whereas those of thirty head and neck patients ranged between 0.0 and 6.0 mm. Setup errors ranged from 0.0 mm to 9.0 mm for thirty breast patients and thirty lung patients. Thirty individuals' bladder diameters fell between 0.0 mm and 7.0 mm. For thirty individuals with rectum measurements between 0.0 and 8.0 mm and thirty patients with prostate measurements between 0.0 mm and 9.0 mm. CTV to PTV ratios for Brain are 3.0 mm, Head and Neck are 3.7 mm, Breast is 5.1 mm, Lung is 6.5 mm, Bladder is 3.5 mm, Rectum is 4.1 mm, and Prostate is 4.3 mm. Conclusion: The usage of EPID for patient setup verification is an effective method. The setup errors depend on the location of the tumour, therefore it is crucial to determine the right CTV-to-PTV margin. Our study's computed margins correspond to those that have been published.

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