A Novel Absorbable Radiopaque Hydrogel Spacer to Separate the Head of the Pancreas and Duodenum in Radiation Therapy for Pancreatic Cancer

Avani D. Rao, Ziwei Feng, Eun Shin, Jin He, Kevin M. Waters, Stephanie Coquia, Robert DeJong, Lauren M. Rosati, Lin Su, Dengwang Li, Juan Jackson, Stephen Clark, Jeffrey Schultz, Danielle Hutchings, Seong Hun Kim, Ralph H Hruban, Theodore DeWeese, John Wong, Amol Narang, Joseph M. HermanKai Ding

Research output: Contribution to journalArticle

Abstract

Purpose: We assessed the feasibility and theoretical dosimetric advantages of an injectable hydrogel to increase the space between the head of the pancreas (HOP) and duodenum in a human cadaveric model. Methods and Materials: Using 3 human cadaveric specimens, an absorbable radiopaque hydrogel was injected between the HOP and duodenum by way of open laparotomy in 1 case and endoscopic ultrasound (EUS) guidance in 2 cases. The cadavers were subsequently imaged using computed tomography and dissected for histologic confirmation of hydrogel placement. The duodenal dose reduction and planning target volume (PTV) coverage were characterized using pre- and postspacer injection stereotactic body radiation therapy (SBRT) plans for the 2 cadavers with EUS-guided placement, the delivery method that appeared the most clinically desirable. Modeling studies were performed using 60 SBRT plans consisting of 10 previously treated patients with unresectable pancreatic cancer, each with 6 different HOP-duodenum separation distances. The duodenal volume receiving 15 Gy (V15), 20 Gy (V20), and 33 Gy (V33) was assessed for each iteration. Results: In the 3 cadaveric studies, an average of 0.9 cm, 1.1 cm, and 0.9 cm HOP-duodenum separation was achieved. In the 2 EUS cases, the V20 decreased from 3.86 cm3 to 0.36 cm3 and 3.75 cm3 to 1.08 cm3 (treatment constraint <3 cm3), and the V15 decreased from 7.07 cm3 to 2.02 cm3 and 9.12 cm3 to 3.91 cm3 (treatment constraint <9 cm3). The PTV coverage improved or was comparable between the pre- and postinjection studies. Modeling studies demonstrated that a separation of 8 mm was sufficient to consistently reduce the V15, V20, and V33 to acceptable clinical constraints. Conclusions: Currently, dose escalation has been limited owing to radiosensitive structures adjacent to the pancreas. We demonstrated the feasibility of hydrogel separation of the HOP and duodenum. Future studies will evaluate the safety and efficacy of this technique with the potential for more effective dose escalation using SBRT or intensity-modulated radiation therapy to improve the outcomes in patients with unresectable pancreatic cancer.

Original languageEnglish (US)
JournalInternational Journal of Radiation Oncology Biology Physics
DOIs
StateAccepted/In press - 2017

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pancreas
Hydrogel
Pancreatic Neoplasms
Duodenum
spacers
Pancreas
radiation therapy
Radiotherapy
cancer
Cadaver
dosage
planning
Injections
Laparotomy
iteration
radiant flux density
safety
delivery
tomography
Tomography

ASJC Scopus subject areas

  • Radiation
  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

Cite this

A Novel Absorbable Radiopaque Hydrogel Spacer to Separate the Head of the Pancreas and Duodenum in Radiation Therapy for Pancreatic Cancer. / Rao, Avani D.; Feng, Ziwei; Shin, Eun; He, Jin; Waters, Kevin M.; Coquia, Stephanie; DeJong, Robert; Rosati, Lauren M.; Su, Lin; Li, Dengwang; Jackson, Juan; Clark, Stephen; Schultz, Jeffrey; Hutchings, Danielle; Kim, Seong Hun; Hruban, Ralph H; DeWeese, Theodore; Wong, John; Narang, Amol; Herman, Joseph M.; Ding, Kai.

In: International Journal of Radiation Oncology Biology Physics, 2017.

Research output: Contribution to journalArticle

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title = "A Novel Absorbable Radiopaque Hydrogel Spacer to Separate the Head of the Pancreas and Duodenum in Radiation Therapy for Pancreatic Cancer",
abstract = "Purpose: We assessed the feasibility and theoretical dosimetric advantages of an injectable hydrogel to increase the space between the head of the pancreas (HOP) and duodenum in a human cadaveric model. Methods and Materials: Using 3 human cadaveric specimens, an absorbable radiopaque hydrogel was injected between the HOP and duodenum by way of open laparotomy in 1 case and endoscopic ultrasound (EUS) guidance in 2 cases. The cadavers were subsequently imaged using computed tomography and dissected for histologic confirmation of hydrogel placement. The duodenal dose reduction and planning target volume (PTV) coverage were characterized using pre- and postspacer injection stereotactic body radiation therapy (SBRT) plans for the 2 cadavers with EUS-guided placement, the delivery method that appeared the most clinically desirable. Modeling studies were performed using 60 SBRT plans consisting of 10 previously treated patients with unresectable pancreatic cancer, each with 6 different HOP-duodenum separation distances. The duodenal volume receiving 15 Gy (V15), 20 Gy (V20), and 33 Gy (V33) was assessed for each iteration. Results: In the 3 cadaveric studies, an average of 0.9 cm, 1.1 cm, and 0.9 cm HOP-duodenum separation was achieved. In the 2 EUS cases, the V20 decreased from 3.86 cm3 to 0.36 cm3 and 3.75 cm3 to 1.08 cm3 (treatment constraint <3 cm3), and the V15 decreased from 7.07 cm3 to 2.02 cm3 and 9.12 cm3 to 3.91 cm3 (treatment constraint <9 cm3). The PTV coverage improved or was comparable between the pre- and postinjection studies. Modeling studies demonstrated that a separation of 8 mm was sufficient to consistently reduce the V15, V20, and V33 to acceptable clinical constraints. Conclusions: Currently, dose escalation has been limited owing to radiosensitive structures adjacent to the pancreas. We demonstrated the feasibility of hydrogel separation of the HOP and duodenum. Future studies will evaluate the safety and efficacy of this technique with the potential for more effective dose escalation using SBRT or intensity-modulated radiation therapy to improve the outcomes in patients with unresectable pancreatic cancer.",
author = "Rao, {Avani D.} and Ziwei Feng and Eun Shin and Jin He and Waters, {Kevin M.} and Stephanie Coquia and Robert DeJong and Rosati, {Lauren M.} and Lin Su and Dengwang Li and Juan Jackson and Stephen Clark and Jeffrey Schultz and Danielle Hutchings and Kim, {Seong Hun} and Hruban, {Ralph H} and Theodore DeWeese and John Wong and Amol Narang and Herman, {Joseph M.} and Kai Ding",
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T1 - A Novel Absorbable Radiopaque Hydrogel Spacer to Separate the Head of the Pancreas and Duodenum in Radiation Therapy for Pancreatic Cancer

AU - Rao, Avani D.

AU - Feng, Ziwei

AU - Shin, Eun

AU - He, Jin

AU - Waters, Kevin M.

AU - Coquia, Stephanie

AU - DeJong, Robert

AU - Rosati, Lauren M.

AU - Su, Lin

AU - Li, Dengwang

AU - Jackson, Juan

AU - Clark, Stephen

AU - Schultz, Jeffrey

AU - Hutchings, Danielle

AU - Kim, Seong Hun

AU - Hruban, Ralph H

AU - DeWeese, Theodore

AU - Wong, John

AU - Narang, Amol

AU - Herman, Joseph M.

AU - Ding, Kai

PY - 2017

Y1 - 2017

N2 - Purpose: We assessed the feasibility and theoretical dosimetric advantages of an injectable hydrogel to increase the space between the head of the pancreas (HOP) and duodenum in a human cadaveric model. Methods and Materials: Using 3 human cadaveric specimens, an absorbable radiopaque hydrogel was injected between the HOP and duodenum by way of open laparotomy in 1 case and endoscopic ultrasound (EUS) guidance in 2 cases. The cadavers were subsequently imaged using computed tomography and dissected for histologic confirmation of hydrogel placement. The duodenal dose reduction and planning target volume (PTV) coverage were characterized using pre- and postspacer injection stereotactic body radiation therapy (SBRT) plans for the 2 cadavers with EUS-guided placement, the delivery method that appeared the most clinically desirable. Modeling studies were performed using 60 SBRT plans consisting of 10 previously treated patients with unresectable pancreatic cancer, each with 6 different HOP-duodenum separation distances. The duodenal volume receiving 15 Gy (V15), 20 Gy (V20), and 33 Gy (V33) was assessed for each iteration. Results: In the 3 cadaveric studies, an average of 0.9 cm, 1.1 cm, and 0.9 cm HOP-duodenum separation was achieved. In the 2 EUS cases, the V20 decreased from 3.86 cm3 to 0.36 cm3 and 3.75 cm3 to 1.08 cm3 (treatment constraint <3 cm3), and the V15 decreased from 7.07 cm3 to 2.02 cm3 and 9.12 cm3 to 3.91 cm3 (treatment constraint <9 cm3). The PTV coverage improved or was comparable between the pre- and postinjection studies. Modeling studies demonstrated that a separation of 8 mm was sufficient to consistently reduce the V15, V20, and V33 to acceptable clinical constraints. Conclusions: Currently, dose escalation has been limited owing to radiosensitive structures adjacent to the pancreas. We demonstrated the feasibility of hydrogel separation of the HOP and duodenum. Future studies will evaluate the safety and efficacy of this technique with the potential for more effective dose escalation using SBRT or intensity-modulated radiation therapy to improve the outcomes in patients with unresectable pancreatic cancer.

AB - Purpose: We assessed the feasibility and theoretical dosimetric advantages of an injectable hydrogel to increase the space between the head of the pancreas (HOP) and duodenum in a human cadaveric model. Methods and Materials: Using 3 human cadaveric specimens, an absorbable radiopaque hydrogel was injected between the HOP and duodenum by way of open laparotomy in 1 case and endoscopic ultrasound (EUS) guidance in 2 cases. The cadavers were subsequently imaged using computed tomography and dissected for histologic confirmation of hydrogel placement. The duodenal dose reduction and planning target volume (PTV) coverage were characterized using pre- and postspacer injection stereotactic body radiation therapy (SBRT) plans for the 2 cadavers with EUS-guided placement, the delivery method that appeared the most clinically desirable. Modeling studies were performed using 60 SBRT plans consisting of 10 previously treated patients with unresectable pancreatic cancer, each with 6 different HOP-duodenum separation distances. The duodenal volume receiving 15 Gy (V15), 20 Gy (V20), and 33 Gy (V33) was assessed for each iteration. Results: In the 3 cadaveric studies, an average of 0.9 cm, 1.1 cm, and 0.9 cm HOP-duodenum separation was achieved. In the 2 EUS cases, the V20 decreased from 3.86 cm3 to 0.36 cm3 and 3.75 cm3 to 1.08 cm3 (treatment constraint <3 cm3), and the V15 decreased from 7.07 cm3 to 2.02 cm3 and 9.12 cm3 to 3.91 cm3 (treatment constraint <9 cm3). The PTV coverage improved or was comparable between the pre- and postinjection studies. Modeling studies demonstrated that a separation of 8 mm was sufficient to consistently reduce the V15, V20, and V33 to acceptable clinical constraints. Conclusions: Currently, dose escalation has been limited owing to radiosensitive structures adjacent to the pancreas. We demonstrated the feasibility of hydrogel separation of the HOP and duodenum. Future studies will evaluate the safety and efficacy of this technique with the potential for more effective dose escalation using SBRT or intensity-modulated radiation therapy to improve the outcomes in patients with unresectable pancreatic cancer.

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