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Title: SU-E-J-65: Motion Difference Between the Pancreas and Nearby Veins for Pancreas Motion Monitoring Using Ultrasound During Radiation Therapy

Abstract

Purpose: As it is generally difficult to outline the pancreas on an ultrasound b-mode image, visualized structures such as the portal or the splenic veins are assumed to have the same motion as the pancreas. These structures can be used as a surrogate for monitoring pancreas motion during radiation therapy (RT) delivery using ultrasound. To verify this assumption, we studied the motion difference between the head of the pancreas, the portal vein, the tail of the pancreas, and splenic vein. Methods: 4DCT data acquired during RT simulation were analyzed for a total of 5 randomly selected patients with pancreatic cancer. The data was sorted into 10 respiratory phases from 0% to 90% (0%: end of the inspiration, 50%: end of expiration) . The head of the pancreas (HP), tail of the pancreas (TP), portal vein (PV), and splenic vein (SV) were contoured on all 10 phases. The volume change and motion were measured in the left-right (LR), anterior-superior (AP), and superior-inferior (SI) directions. Results: The volume change for all patients/phases were: 1.2 ± 3% for HP, 0.78 ± 1.6% for PV, 2.5 ± 2.9% for TP, and 0.53 ± 2.1% for SV. Motion for each structure was estimated from themore » centroid displacements due to the uniformity of the structures and the small volume change. The measured motion between HP and PV was: LR: 0.1 ± 0.17 mm, AP: 0.04 ± 0.1 mm, SI: 0.17 ± 0.16 mm and between TP and the PV was: LR: 0.05 ± 0.3 mm, AP: 0.1 ± 0.4 mm, SI: 0.01 ± 0.022 mm. Conclusion: There are small motion differences between the portal vein and the head of the pancreas, and the splenic vein and the tail of the pancreas. This suggests the feasibility of utilizing these features for monitoring the pancreas motion during radiation therapy.« less

Authors:
; ;  [1];  [2]
  1. Medical College of Wisconsin, Milwaukee, WI (United States)
  2. Qianfoshan Hospital Shandong University, Jinan, Shandong (China)
Publication Date:
OSTI Identifier:
22494085
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 42; Journal Issue: 6; Other Information: (c) 2015 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; HEAD; IMAGES; NEOPLASMS; PANCREAS; PATIENTS; RADIOTHERAPY; RANDOMNESS; SIMULATION; VEINS

Citation Formats

Omari, E, Erickson, B, Li, X, and Zhang, J. SU-E-J-65: Motion Difference Between the Pancreas and Nearby Veins for Pancreas Motion Monitoring Using Ultrasound During Radiation Therapy. United States: N. p., 2015. Web. doi:10.1118/1.4924152.
Omari, E, Erickson, B, Li, X, & Zhang, J. SU-E-J-65: Motion Difference Between the Pancreas and Nearby Veins for Pancreas Motion Monitoring Using Ultrasound During Radiation Therapy. United States. doi:10.1118/1.4924152.
Omari, E, Erickson, B, Li, X, and Zhang, J. Mon . "SU-E-J-65: Motion Difference Between the Pancreas and Nearby Veins for Pancreas Motion Monitoring Using Ultrasound During Radiation Therapy". United States. doi:10.1118/1.4924152.
@article{osti_22494085,
title = {SU-E-J-65: Motion Difference Between the Pancreas and Nearby Veins for Pancreas Motion Monitoring Using Ultrasound During Radiation Therapy},
author = {Omari, E and Erickson, B and Li, X and Zhang, J},
abstractNote = {Purpose: As it is generally difficult to outline the pancreas on an ultrasound b-mode image, visualized structures such as the portal or the splenic veins are assumed to have the same motion as the pancreas. These structures can be used as a surrogate for monitoring pancreas motion during radiation therapy (RT) delivery using ultrasound. To verify this assumption, we studied the motion difference between the head of the pancreas, the portal vein, the tail of the pancreas, and splenic vein. Methods: 4DCT data acquired during RT simulation were analyzed for a total of 5 randomly selected patients with pancreatic cancer. The data was sorted into 10 respiratory phases from 0% to 90% (0%: end of the inspiration, 50%: end of expiration) . The head of the pancreas (HP), tail of the pancreas (TP), portal vein (PV), and splenic vein (SV) were contoured on all 10 phases. The volume change and motion were measured in the left-right (LR), anterior-superior (AP), and superior-inferior (SI) directions. Results: The volume change for all patients/phases were: 1.2 ± 3% for HP, 0.78 ± 1.6% for PV, 2.5 ± 2.9% for TP, and 0.53 ± 2.1% for SV. Motion for each structure was estimated from the centroid displacements due to the uniformity of the structures and the small volume change. The measured motion between HP and PV was: LR: 0.1 ± 0.17 mm, AP: 0.04 ± 0.1 mm, SI: 0.17 ± 0.16 mm and between TP and the PV was: LR: 0.05 ± 0.3 mm, AP: 0.1 ± 0.4 mm, SI: 0.01 ± 0.022 mm. Conclusion: There are small motion differences between the portal vein and the head of the pancreas, and the splenic vein and the tail of the pancreas. This suggests the feasibility of utilizing these features for monitoring the pancreas motion during radiation therapy.},
doi = {10.1118/1.4924152},
journal = {Medical Physics},
number = 6,
volume = 42,
place = {United States},
year = {Mon Jun 15 00:00:00 EDT 2015},
month = {Mon Jun 15 00:00:00 EDT 2015}
}
  • Purpose: Substantial target motion during the delivery of radiation therapy (RT) for pancreatic cancer is well recognized as a major limiting factor on RT effectiveness. The aim of this work is to monitor intra-fractional motion of the pancreas using ultrasound during RT delivery. Methods: Transabdominal Ultrasound B-mode images were collected from 5 volunteers using a research version of the Clarity Autoscan System (Elekta). The autoscan transducer with center frequency of 5 MHz was utilized for the scans. Imaging parameters were adjusted to acquire images at the desired depth with good contrast and a wide sweep angle. Since well-defined boundaries ofmore » the pancreas can be difficult to find on ultrasound B-mode images, the portal vein was selected as a surrogate for motion estimation of the head of the pancreas. The selection was due to its anatomical location posterior to the neck of the pancreas and close proximity to the pancreas head. The portal vein was contoured on the ultrasound images acquired during simulation using the Clarity Research AFC Workstation software. Volunteers were set up in a similar manner to the simulation for their monitoring session and the ultrasound transducer was mounted on an arm fixed to the couch. A video segment of the portal vein motion was captured. Results: The portal vein was visualized and segmented. Successful monitoring sessions of the portal vein were observed. In addition, our results showed that the ultrasound transducer itself reduces breathing related motion. This is analogous to the use of a compression plate to suppress respiration motion during thorax or abdominal irradiation. Conclusion: We demonstrate the feasibility of tracking the pancreas through the localization of the portal vein using abdominal ultrasound. This will allow for real-time tracking of the intra-fractional motion to justify PTV-margin and to account for unusual motions, thus, improving normal tissue sparing. This research was funding in part by Elekta Inc.« less
  • Purpose Ultrasound tracking of target motion relies on visibility of vascular and/or anatomical landmark. However this is challenging when the target is located far from vascular structures or in organs that lack ultrasound landmark structure, such as in the case of pancreas cancer. The purpose of this study is to evaluate visibility, artifacts and distortions of fusion coils and solid gold markers in ultrasound, CT, CBCT and kV images to identify markers suitable for real-time ultrasound tracking of tumor motion in SBRT pancreas treatment. Methods Two fusion coils (1mm × 5mm and 1mm × 10 mm) and a solid goldmore » marker (0.8mm × 10mm) were embedded in a tissue–like ultrasound phantom. The phantom (5cm × 12cm × 20cm) was prepared using water, gelatin and psyllium-hydrophilic-mucilloid fiber. Psylliumhydrophilic mucilloid acts as scattering medium to produce echo texture that simulates sonographic appearance of human tissue in ultrasound images while maintaining electron density close to that of water in CT images. Ultrasound images were acquired using 3D-ultrasound system with markers embedded at 5, 10 and 15mm depth from phantom surface. CT images were acquired using Philips Big Bore CT while CBCT and kV images were acquired with XVI-system (Elexta). Visual analysis was performed to compare visibility of the markers and visibility score (1 to 3) were assigned. Results All markers embedded at various depths are clearly visible (score of 3) in ultrasound images. Good visibility of all markers is observed in CT, CBCT and kV images. The degree of artifact produced by the markers in CT and CBCT images are indistinguishable. No distortion is observed in images from any modalities. Conclusion All markers are visible in images across all modalities in this homogenous tissue-like phantom. Human subject data is necessary to confirm the marker type suitable for real-time ultrasound tracking of tumor motion in SBRT pancreas treatment.« less
  • Purpose: Currently there is an urgent need in Radiation Therapy for noninvasive and nonionizing soft tissue target guidance such as localization before treatment and continuous monitoring during treatment. Ultrasound is a portable, low cost option that can be easily integrated with the LINAC room. We are developing a cooperatively controlled robot arm that has high intrafraction reproducibility with repositioning of the ultrasound probe. In this study, we introduce virtual springs (VS) to assist with interfraction probe repositioning and we compare the soft tissue deformation introduced by VS to the deformation that would exist without them. Methods: Three metal markers weremore » surgically implanted in the kidney of one dog. The dog was anesthetized and immobilized supine in an alpha cradle. The reference ultrasound probe position and force to ideally visualize the kidney was defined by an experienced ultrasonographer using the Clarity ultrasound system and robot sensor. For each interfraction study, the dog was removed from the cradle and re-setup based on CBCT with bony anatomy alignment to mimic regular patient setup. The ultrasound probe was automatically returned to the reference position using the robot. To accommodate the soft tissue anatomy changes between each setup the operator used the VS feature to adjust the probe and obtain an ultrasound image that matched the reference image. CBCT images were acquired and each interfraction marker location was compared with the first interfraction Result. Results: Analysis of the marker positions revealed that the kidney was displaced by 18.8 ± 6.4 mm without VS and 19.9 ± 10.5 mm with VS. No statistically significant differences were found between two procedures. Conclusion: The VS feature is necessary to obtain matching ultrasound images, and they do not introduce further changes to the tissue deformation. Future work will focus on automatic VS based on ultrasound feedback. Supported in part by: NCI R01 CA161613; Elekta Sponsored Research.« less
  • Purpose: To quantify patient motion during hypo-fractionated prostate cancer treatment as tracked by Calypso™ 4D localization system. Methods: 50 prostate cancer patients with implanted Calypso beacons underwent hypofractionated IMRT treatment. Typical fraction size was 5 with doses of 5–8 Gy/fraction. 213 traces from the 50 patients were analyzed to quantify the probability of motion vs time starting from beam-on. Couch corrections applied by therapists were undone to obtain the natural course of patient motion. The Calypso data was used to identify vector displacements greater than 2 mm from the starting position. The direction of this vector was classified into onemore » of the 26 directions (combinations of L/R, A/P, S/I). The probability of motion >2mm was estimated by computing the fraction of traces that exceed the 2mm threshold at each time point. The violating motion points were also binned by direction in order to identify specific directions that were more prone to movement. Results: The overall probability of motion greater than 2 mm at 5 and 10 minutes from beam-on were 27 % and 50% respectively. The primary directions in which motion occurred were Posterior-Inferior (PI) and Inferior (I) with a probability of 8.5% and 4% at 5 minutes and 10% for both at 10 minutes. Motion was classified into the following bins: 0–2, 2–3, 3–4, 4–5, 5–6, 6–7, 7–8 and greater than 8 mm. It is observed that motion < 2mm decreases from the first 5 minutes to the next while the higher magnitude components increase with time. Conclusion: The probability of prostate motion increases with time. The trend seen in the PI and I directions can be attributed to physiological factors like bladder filling. This probability can be factored in for scheduling intrafraction imaging and used to compare dosimetric impact of VMAT vs. IMRT plans. This work is supported in part by Varian Medical Systems.« less
  • Purpose: To describe an in-house video goggle feedback system for motion management during simulation and treatment of radiation therapy patients. Methods: This video goggle system works by splitting and amplifying the video output signal directly from the Varian Real-Time Position Management (RPM) workstation or TrueBeam imaging workstation into two signals using a Distribution Amplifier. The first signal S[1] gets reconnected back to the monitor. The second signal S[2] gets connected to the input of a Video Scaler. The S[2] signal can be scaled, cropped and panned in real time to display only the relevant information to the patient. The outputmore » signal from the Video Scaler gets connected to an HDMI Extender Transmitter via a DVI-D to HDMI converter cable. The S[2] signal can be transported from the HDMI Extender Transmitter to the HDMI Extender Receiver located inside the treatment room via a Cat5e/6 cable. Inside the treatment room, the HDMI Extender Receiver is permanently mounted on the wall near the conduit where the Cat5e/6 cable is located. An HDMI cable is used to connect from the output of the HDMI Receiver to the video goggles. Results: This video goggle feedback system is currently being used at two institutions. At one institution, the system was just recently implemented for simulation and treatments on two breath-hold gated patients with 8+ total fractions over a two month period. At the other institution, the system was used to treat 100+ breath-hold gated patients on three Varian TrueBeam linacs and has been operational for twelve months. The average time to prepare the video goggle system for treatment is less than 1 minute. Conclusion: The video goggle system provides an efficient and reliable method to set up a video feedback signal for radiotherapy patients with motion management.« less