Abolfazl Kanani - Ionizing and Non-Ionizing Radiation Protection Research Center (INIRPRC), School of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, Iran
Ali Fatemi-Ardakani - Department of Physics, Jackson State University (JSU), Jackson, Mississippi, USA
Amir M. Owrangi - Department of Radiation Oncology, UT Southwestern Medical Center, ۲۲۸۰ Inwood Rd, EC۲.۲۴۲, Dallas, TX ۷۵۲۳۵, USA
Mehran Yazdi - Signal and Image Processing Lab (SIPL), School of Electrical and Computer Eng, Shiraz University, Shiraz, Iran
Hadi Baghbani - Department of Radiology, Namazi Hospital, Shiraz University of Medical Sciences, Shiraz, Iran
Mohammad Amin Mosleh-Shirazi - Ionizing and Non-Ionizing Radiation Protection Research Center (INIRPRC), School of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, Iran

Background: The BEBIG Portio multi-channel applicator provides better target dose coverage and sparing organs-at-risk compared to a single-channel cylinder. However, artifacts and distortions of Portio in magnetic resonance images (MRI) have not yet been reported.Objective: We aimed to quantify the artifacts and distortions in its ۱.۵-Tesla MR images before clinical use.Material and Methods: In this experimental study, we employed a gelatin-filled phantom to conduct our measurements. T۲-weighted (T۲W) images were examined for artifacts and distortions. Computed tomography (CT) images were used as a reference to assess image distortions. Artifact severity was measured by recording the full-width-at-half-maximum (FWHM) image pixel values at various positions along the length of the applicator/channels. CT and MRI-based applicator reconstruction accuracy were then compared, and signal-to-noise ratio (SNR) and contrast were also determined for the applicator images.Results: The applicator distortion level for the Portio applicator was less than the image spatial resolution (۰.۵±۰.۵ pixels). The average FWHM for the tandem applicator images was ۵.۲۳±۰.۳۹ mm, while it was ۳.۲۱±۰.۳۷ mm for all channels (compared to their actual diameters of ۵.۰ mm and ۳.۰ mm, respectively). The average applicator reconstruction difference between CT and MR images was ۰.۷۵±۰.۳۰ mm overall source dwell positions. The image SNR and contrast were both acceptable. Conclusion: These findings indicate that the Portio applicator has a satisfactory low level of artifacts and image distortions in ۱.۵-Tesla, T۲W images. It may, therefore, be a promising option for MRI-guided multi-channel vaginal brachytherapy.

Magnetic Resonance Imaging, Radiotherapy, Brachytherapy, Portio Applicator, Image Processing, Gynecolgical, Endometrial cancer