Finite Element-Based Personalized Simulation of Duodenal Hydrogel Spacer: Spacer Location Dependent Duodenal Sparing and a Decision Support System for Spacer-Enabled Pancreatic Cancer Radiation Therapy

Hooshangnejad, Hamed; Youssefian, Sina; Narang, Amol; Shin, Eun Ji; Rao, Avani D.; Han‐Oh, Sarah; McNutt, Todd; Lee, Junghoon; Hu, Chen; Wong, John W.; Ding, Kai

doi:10.3389/fonc.2022.833231

Cited by 9 publications

(5 citation statements)

References 47 publications

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“…Previously, we have applied FEMOSSA to rectal spacer and shown its advantages over previous models 23 . Recently, we have applied FEMOSSA to duodenal spacer and shown that FEMOSSA can be used for simulating different scenarios of spacer placement to get a better insight into various aspects of duodenal hydrogel spacer 24,40 and potentially other sites 41 . All these studies demonstrate the versatility of FEMOSSA and its potential to be used for other hydrogel spacer‐related applications such as drug delivery using hydrogels, 42 biomaterial delivery, 43 and plastic surgery 44 .…”

Section: Discussionmentioning

confidence: 99%

Demonstrating the benefits of corrective intraoperative feedback in improving the quality of duodenal hydrogel spacer placement

Hooshangnejad

Han‐Oh

Shin³

et al. 2022

Medical Physics

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Purpose Pancreatic cancer is the fourth leading cause of cancer‐related death with a 10% 5‐year overall survival rate (OS). Radiation therapy (RT) in addition to dose escalation improves the outcome by significantly increasing the OS at 2 and 3 years but is hindered by the toxicity of the duodenum. Our group showed that the insertion of hydrogel spacer reduces duodenal toxicity, but the complex anatomy and the demanding procedure make the benefits highly uncertain. Here, we investigated the feasibility of augmenting the workflow with intraoperative feedback to reduce the adverse effects of the uncertainties. Materials and Methods We simulated three scenarios of the virtual spacer for four cadavers with two types of gross tumor volume (GTV) (small and large); first, the ideal injection; second, the nonideal injection that incorporates common spacer placement uncertainties; and third, the corrective injection that uses the simulation result from nonideal injection and is designed to compensate for the effect of uncertainties. We considered two common uncertainties: (1) “Narrowing” is defined as the injection of smaller spacer volume than planned. (2) “Missing part” is defined as failure to inject spacer in the ascending section of the duodenum. A total of 32 stereotactic body radiation therapy (SBRT) plans (33 Gy in 5 fractions) were designed, for four cadavers, two GTV sizes, and two types of uncertainties. The preinjection scenario for each case was compared with three scenarios of virtual spacer placement from the dosimetric and geometric points of view. Results We found that the overlapping PTV space with the duodenum is an informative quantity for determining the effective location of the spacer. The ideal spacer distribution reduced the duodenal V33Gy for small and large GTV to less than 0.3 and 0.1cc, from an average of 3.3cc, and 1.2cc for the preinjection scenario. However, spacer placement uncertainties reduced the efficacy of the spacer in sparing the duodenum (duodenal V33Gy: 1.3 and 0.4cc). The separation between duodenum and GTV decreased by an average of 5.3 and 4.6 mm. The corrective feedback can effectively bring back the expected benefits from the ideal location of the spacer (averaged V33Gy of 0.4 and 0.1cc). Conclusions An informative feedback metric was introduced and used to mitigate the effect of spacer placement uncertainties and maximize the benefits of the EUS‐guided procedure.

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Section: Discussionmentioning

confidence: 99%

Demonstrating the benefits of corrective intraoperative feedback in improving the quality of duodenal hydrogel spacer placement

Hooshangnejad

Han‐Oh

Shin³

et al. 2022

Medical Physics

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“…All analyses were done using our MATLAB‐based in‐house image processing toolbox. 16 , 35 , 36 , 37 , 38 , 39 , 40 Figure 1 shows a typical case of the original SpaceOAR (a) and simulated iodinated spacer (b). We used the CT scans with simulated iodinated spacer for the rest of the study.…”

Section: Methodsmentioning

confidence: 99%

“…3D smoothing was applied to reduce the pixelation effect and simulate the realistic texture of hydrogel. All analyses were done using our MATLAB‐based in‐house image processing toolbox 16,35–40 . Figure 1 shows a typical case of the original SpaceOAR (a) and simulated iodinated spacer (b).…”

Section: Methodsmentioning

confidence: 99%

Systematic study of the iodinated rectal hydrogel spacer material discrepancy on accuracy of proton dosimetry

Hooshangnejad

Han

Feng

et al. 2022

J Applied Clin Med Phys

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Purpose Iodination of rectal hydrogel spacer increases the computed tomography (CT) visibility. The effect of iodinated hydrogel spacer material on the accuracy of proton dosimetry has not been fully studied yet. We presented a systematic study to determine the effect of iodination on proton dosimetry accuracy during proton therapy (PT). Methods PT plans were designed for 20 prostate cancer patients with rectal hydrogel spacer. Three variations of hydrogel density were considered. First, as the ground truth, the true elemental composition of hydrogel true material (TM), verified by our measurement of spacer stopping power ratio, was used for plan optimization and Monte Carlo dose calculation. The dose distribution was recalculated with (1) no material (NM) override based on the CT intensity of the iodinated spacer, and (2) the water material (WM) override, where spacer material was replaced by water. The plans were compared with the ground truth using the metrics of gamma index (GI) and dosimetric indices. Results The iodination of hydrogel spacer affected the proton dose distribution with the NM scenario showing the most deviation from the ground truth. The iodination of spacer resulted in a notable increase in CT intensity and led to the treatment planning systems mistreating the iodinated spacer as a high‐density material. Among the structures adjacent to the target, neurovascular bundles showed the largest dose difference, up to 350 cGy or about 5% of the prescribed dose with NM. Compared to the WM scenario, dose distribution similarity and GI passing ratios were lower in the NM scenario. Conclusion The inaccurate CT intensity‐based material for iodinated spacer resulted in errors in PT dose calculation. We found that the error was negligible if the iodinated spacer was replaced with water. Water density can be used as a clinically accessible and convenient alternative material override to true spacer material.

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“…[2][3][4][5][6] One-third of the patients manifest locally advanced stage and are greatly at risk of distant progression. 7 Stereotactic body radiation therapy (SBRT) is an advanced radiotherapy (RT) delivery technique where higher doses are delivered in a hypofractionation regime. SBRT is an effective anti-cancer treatment to achieve local control.…”

Section: Introductionmentioning

confidence: 99%

FLEX-RT: feasibility study of using flexible array transducer for tumor motion tracking in pancreatic cancer radiotherapy

Hooshangnejad,

China,

Uneri

et al. 2024

Medical Imaging 2024: Ultrasonic Imaging and Tomography

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Purpose: Pancreatic cancer is one of the deadliest cancer types with less than a 10% 3-year survival rate (SR). Radiotherapy (RT) is critical for achieving local control and enabling dose escalation, which can double and triple the 2-year and 3-year SR. However, intrafraction organs at risk (OAR) and target motion cause considerable uncertainty in dose delivery. Motion management, such as via beam gating triggered by ultrasound (US) guidance, can mitigate these uncertainties without the need for large safety margins that increase OAR dose and toxicity. Methods:We propose a novel motion management technique for pancreatic cancer radiotherapy called FLEX-RT, which uses real-time US images acquired by the flexible array transducer (FLEX). We created a motion phantom for simulating the pancreas' motion. A realistic model of the pancreas and duodenum was floated in a water tank over two straps that were connected to a respiratory motion platform with alternating motion. To evaluate the head of the pancreas, we compared the measured motion from the generic L7-4 probe (reference) with the FLEX. We then virtually placed FLEX on the patient's body in the CT scans of ten pancreatic cancer patients treated at our institution. To evaluate the feasibility of FLEX for motion tracking, we compared the dose distribution for (i) without FLEX, (ii) with FLEX and beam avoidance, and (iii) with FLEX and without beam avoidance.Results: Both L7-4 and FLEX could successfully track the induced motion, with similar amplitude and cross-correlation of 0.76. The dosimetric analysis showed that FLEX can be used directly during treatment, with minimal impact on dose distribution. Not accounting for the probe caused a minor PTV coverage drop ranging from 1% to 3%.Conclusions: FLEX-RT, RT with FLEX-enabled motion management, is a novel and feasible solution for the longstanding problem of high motion uncertainty of pancreatic cancer RT.

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Finite Element-Based Personalized Simulation of Duodenal Hydrogel Spacer: Spacer Location Dependent Duodenal Sparing and a Decision Support System for Spacer-Enabled Pancreatic Cancer Radiation Therapy

Cited by 9 publications

References 47 publications

Demonstrating the benefits of corrective intraoperative feedback in improving the quality of duodenal hydrogel spacer placement

Demonstrating the benefits of corrective intraoperative feedback in improving the quality of duodenal hydrogel spacer placement

Systematic study of the iodinated rectal hydrogel spacer material discrepancy on accuracy of proton dosimetry

FLEX-RT: feasibility study of using flexible array transducer for tumor motion tracking in pancreatic cancer radiotherapy

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