Ueda Y, Ikezawa K, Sagawa T, Isono M, Ohira S, Miyazaki M, Takada R, Yamai T, Ohkawa K, Teshima T, and Konishi K
There is little evidence regarding radiation dose perturbation caused by the self-expandable metallic stents (SEMSs) used for transpapillary biliary decompression. We aimed to compare SEMSs with plastic stents (PSs) and clarify their dosimetric characteristics. Fifteen SEMSs (10 braided and 5 lasercut type) and six PSs (diameter: 2.3-3.3 mm) were inserted into a water-equivalent solid phantom. In total, 13 SEMSs had radiopaque markers, whereas the other two did not. Using radiochromic films, the dose difference adjacent to the stents at locations proximal, distal, and arc delivery to the radiation source was evaluated based on comparison to measurement of the dose delivery in phantom without any stent in place. The median values of the dose difference for each stent were used to compare the SEMS and PS groups.Results: The dose difference (median (minimum/maximum)) was as follows: proximal, SEMSs + 2.1% (1.8 / 4.7) / PSs + 5.4% (4.1 / 6.3) (p < 0.001); distal, SEMSs -1.0% (-1.6 /-0.4) / PSs -8.9% (-11.7 / -7.4) (p < 0.001); arc delivery, SEMSs 1.2% (0.9 / 2.3) / PSs 2.2% (1.6 / 3.6) (p = 0.005). These results demonstrated that the dose differences of SEMSs were significantly smaller than those of PSs. On the other hand, the dose difference was large at surface of the radiopaque markers for SEMSs: proximal, 10.3% (7.2 / 20.9); distal, -8.4% (-16.3 / -4.2); arc delivery, 5.5% (4.2 / 9.2). SEMSs for biliary decompression can be safely used in patients undergoing radiotherapy, by focusing on the dose distribution around the stents and by paying attention to local changes in the dose distribution of radiopaque markers., Competing Interests: Declarations. Ethics approval: This study did not require an Institutional Review Board (IRB) approval and written consent because this study does not include any investigations or experiments with human participants or animals performed by any of the authors. Consent to participate: This study did not require a written consent. Consent to publish: None. Competing interests: Dr. Yoshihiro Ueda reports patent planned with Zeon Medical. Dr. Kenji Ikezawa reports provision of the stents used in this study from Boston Scientific, Olympus Medical Systems, Century Medical, Zeon Medical and Medicos Hirata; grants from ASKA Pharmaceutical; consulting fee from Medicos Hirata, honoraria for lecture from Boston Scientific, Zeon Medical, Kaneka and Medicos Hirata; patent planned with Zeon Medical. Dr. Ryoji Takada reports honoraria for manuscript writing from Medicos Hirata. Drs. Tomohiro Sagawa, Masaru Isono, Shingo Ohira, Masayoshi Miyazaki, Takuo Yamai, Kazuyoshi Ohkawa, Teruki Teshima, and Koji Konishi have no conflicts of interest or financial ties to disclose., (© 2024. Australasian College of Physical Scientists and Engineers in Medicine.)