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Evaluating the effects of metal artifacts on dose distribution of the pelvic region
Nooshin Banaee1, Mehdi Salehi Barough1, Sepideh Asgari1, Elham Hosseinzadeh1, Ehsan Salimi2
1 Department of Medical Radiation, Engineering Faculty, Central Tehran Branch, Islamic Azad University, Tehran, Iran 2 Institute for Research in Fundamental Sciences, Iranian Light Source Facility, Tehran, Iran
Correspondence Address:
Nooshin Banaee, Department of Medical Radiation, Engineering Faculty, Central Tehran Branch, Islamic Azad University, Tehran Iran
 Source of Support: None, Conflict of Interest: None DOI: 10.4103/jcrt.JCRT_786_19
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Aim of the Study: Some cancerous patients have hip prosthesis of metal elements when they undergo radiation therapy. Metal implants are a cause of metal artifacts in computed tomography (CT) images due to their higher density compared to normal tissues. The aim of this study is to evaluate the quantitative effects of metal artifacts on dose distribution of the pelvic region.
Materials and Methods: Seven patients with metal implants in the pelvic region were scanned and CT images were exported to the Monaco treatment planning system. Based on the diagnosis of each patient, three-dimensional plans were implemented on CT images and dose distributions were extracted. At the next step, metal artifacts were contoured and electron densities of these new structures were modified to the extent of soft tissue. Finally, dose distributions and the differences were investigated by VeriSoft software.
Results: The results of this study showed that if the electron density to metal artifacts is not assigned properly, it will increase the calculated monitor units (MUs) by almost 3.78 MUs/fraction which will significantly affect total dose distribution of treatment.
Conclusion: For the precise implementation of the treatment and in order to minimize the systematic errors related to the calculated MUs, necessary corrections on the electron density of metal artifacts should be considered before the treatment planning. The issue will be more critical in advanced treatment modalities where dose escalation is needed.
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