Dose perturbation by metallic biliary stent in external beam radiotherapy of pancreato-biliary cancers

Lee, Ho; Yoon, Jeongmin; Park, Kwangwoo; Rim, Chai Hong; Chung, Moon Jae; Seong, Jinsil

doi:10.1007/s13246-019-00774-1

Cited by 9 publications

(11 citation statements)

References 22 publications

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“…Second, PS and SEMS were not assessed separately, which is necessary, as PS and SEMS differ in diameter and material. Notably, basic data have shown that SEMS enhance the radiation dose around the stent (21). The number of cases and events in the present study was too small to perform a comparative analysis.…”

Section: Discussionmentioning

confidence: 74%

Safety of biliary stent placement followed by definitive chemoradiotherapy in patients with pancreatic cancer with bile duct obstruction

Hayakawa

Ito

Murofushi

et al. 2021

J Gastrointest Oncol

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Background: Although patients with malignant bile duct obstruction due to pancreatic cancer are often initially treated with biliary stent placement, concurrent chemoradiotherapy with stents poses a potential risk of increased toxicity. This retrospective study aimed to evaluate the safety of biliary stent placement followed by definitive concurrent chemoradiotherapy in patients with pancreatic cancer.Methods: Patients with pancreatic cancer who underwent either a plastic stent or a self-expanding metallic stent placement for malignant bile duct obstruction before definitive concurrent chemoradiotherapy were retrospectively reviewed. Radiotherapy was delivered in 1.8 Gy per fraction to a total dose of 50.4 Gy.Gemcitabine, TS-1 plus Gemcitabine, or TS-1 was the concurrent chemotherapy/regimen. The primary endpoint was the rate of biliary stent-related toxicities, defined as biliary bleeding, duodenal perforation, or bile duct perforation.Results: Thirty patients were included. Plastic stents were placed in 23 patients and self-expanding metallic stent in seven patients at the start of irradiation. The median follow-up time was 20 (range, 2-63) months, and 27 patients (90%) completed concurrent chemoradiotherapy. Biliary stent-related toxicity (grade 3 biliary bleeding) was confirmed in one patient (3%) with a plastic stent 9 months after concurrent chemoradiotherapy. The median duration of locoregional control, progression-free survival, and overall survival were 31.1, 7.3, and 10.5 months, respectively. Conclusions: Stent placement followed by concurrent chemoradiotherapy was not associated with an apparent increase in toxicity and may be an appropriate treatment for patients with locally advanced pancreatic head cancer with bile duct obstruction.

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Section: Discussionmentioning

confidence: 74%

Safety of biliary stent placement followed by definitive chemoradiotherapy in patients with pancreatic cancer with bile duct obstruction

Hayakawa

Ito

Murofushi

et al. 2021

J Gastrointest Oncol

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“…For precise dosimetric examination, it is necessary to ensure that the 3D-printed density matches the preset density of the infill ( 14 ). A CT scan of the 3D-printed water-equivalent phantom was performed to calculate the actual density by comparing it with values in an image value-to-density table.…”

Section: Resultsmentioning

confidence: 99%

“…There have been attempts to manufacture customized objects incorporating 3D printing technology into various applications of radiation therapy (11)(12)(13)(14)(15)(16)(17). In this manner, to overcome the limitations of IORT's PSQA, we ensure the stability of IORT by creating a PSQA phantom via 3D printing.…”

Section: Introductionmentioning

confidence: 99%

Patient-Specific Quality Assurance Using a 3D-Printed Chest Phantom for Intraoperative Radiotherapy in Breast Cancer

et al. 2021

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This study aims to confirm the usefulness of patient-specific quality assurance (PSQA) using three-dimensional (3D)-printed phantoms in ensuring the stability of IORT and the precision of the treatment administered. In this study, five patient-specific chest phantoms were fabricated using a 3D printer such that they were dosimetrically equivalent to the chests of actual patients in terms of organ density and shape around the given target, where a spherical applicator was inserted for breast IORT treatment via the INTRABEAM™ system. Models of lungs and soft tissue were fabricated by applying infill ratios corresponding to the mean Hounsfield unit (HU) values calculated from CT scans of the patients. The two models were then assembled into one. A 3D-printed water-equivalent phantom was also fabricated to verify the vendor-provided depth dose curve. Pieces of an EBT3 film were inserted into the 3D-printed customized phantoms to measure the doses. A 10 Gy prescription dose based on the surface of the spherical applicator was delivered and measured through EBT3 films parallel and perpendicular to the axis of the beam. The shapes of the phantoms, CT values, and absorbed doses were compared between the expected and printed ones. The morphological agreement among the five patient-specific 3D chest phantoms was assessed. The mean differences in terms of HU between the patients and the phantoms was 2.2 HU for soft tissue and −26.2 HU for the lungs. The dose irradiated on the surface of the spherical applicator yielded a percent error of −2.16% ± 3.91% between the measured and prescribed doses. In a depth dose comparison using a 3D-printed water phantom, the uncertainty in the measurements based on the EBT3 film decreased as the depth increased beyond 5 mm, and a good agreement in terms of the absolute dose was noted between the EBT3 film and the vendor data. These results demonstrate the applicability of the 3D-printed chest phantom for PSQA in breast IORT. This enhanced precision offers new opportunities for advancements in IORT.

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“…In RT using a proton beam, the effects were evaluated through Monte Carlo (MC) simulations and through measurements using films. These studies were performed to verify the range of the differences in a specific area [ 16 ]. Only a few studies focused on the dosimetric evaluation of the effects that occur in the volume where the stent is inserted.…”

Section: Introductionmentioning

confidence: 99%

Assessment of dose perturbations for metal stent in photon and proton radiotherapy plans for hepatocellular carcinoma

et al. 2022

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Background The present study aimed to investigate the dosimetric impact of metal stent for photon and proton treatment plans in hepatocellular carcinoma. Methods With computed tomography data of a water-equivalent solid phantom, dose perturbation caused by a metal stent included in the photon and proton treatment of hepatocellular carcinoma was evaluated by comparing Eclipse and RayStation treatment planning system (TPS) to a Monte Carlo (MC) based dose calculator. Photon and proton plans were created with anterior–posterior/posterior-anterior (AP/PA) fields using a 6 MV beam and AP/PA fields of a wobbling beam using 150 MeV and a 10 cm ridge filter. The difference in dose distributions and dosimetric parameters were compared depending on the stent's positions (the bile duct (GB) and intestinal tract (GI)) and angles (0°, 45°, and 90°). Additionally, the dose variation in the target volume including the stent was comparatively evaluated through dose volume histogram (DVH) analysis. And the comparison of clinical cases was carried out in the same way. Results Percentage differences in the dosimetric parameters calculated by MC ranged from − 7.0 to 3.9% for the photon plan and − 33.7 to 4.3% for the proton plan, depending on the angle at which the GB and GI stents were placed, compared to those without the stent. The maximum difference was observed at the minimum dose (Dmin), which was observed in both photon and proton plans in the GB and GI stents deployed at a 90° incidence angle. The parameter differences were greater in the proton plan than in photon plan. The target volume showed various dose variations depending on positions and angles of stent for both beams. Compared with no-stent, the doses within the target volume containing the GI and GB stents for the photon beam were overestimated in the high-dose area at 0°, nearly equal within 1% at 45°, and underestimated at 90°. These doses to the proton beam were underestimated at all angles, and the amount of underdose to the target volume increased with an increase in the stent angle. However, the difference was significantly greater with the proton plan than the photon plan. Conclusions Dose perturbations within the target volume due to the presence of the metal stent were not observed in the TPS calculations for photon and proton beams, but MC was used to confirm that there are dose variations within the target volume. The MC results found that delivery of the treatment beam avoiding the stent was the best method to prevent target volume underdose.

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Dose perturbation by metallic biliary stent in external beam radiotherapy of pancreato-biliary cancers

Cited by 9 publications

References 22 publications

Safety of biliary stent placement followed by definitive chemoradiotherapy in patients with pancreatic cancer with bile duct obstruction

Safety of biliary stent placement followed by definitive chemoradiotherapy in patients with pancreatic cancer with bile duct obstruction

Patient-Specific Quality Assurance Using a 3D-Printed Chest Phantom for Intraoperative Radiotherapy in Breast Cancer

Assessment of dose perturbations for metal stent in photon and proton radiotherapy plans for hepatocellular carcinoma

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