Delivery of four-dimensional radiotherapy with TrackBeam for moving target using a dual-layer MLC: Dynamic phantoms study

Yaxi Liu, Chengyu Shi, Bryan Lin, Chul S Ha, Nikos Papanikolaou

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Respiratory motion has been considered a clinical challenge for lung tumor treatments due to target motion. In this study, we aimed to perform an experimental evaluation based on dynamic phantoms using MLC-based beam tracking. TrackBeam, a prototype real-time beam tracking system, has been assembled and evaluated in our clinic. TrackBeam includes an orthogonal dual-layer micro multileaf collimator (DmMLC), an on-board mega-voltage (MV) portal imaging device, and an image processing workstation. With a fiducial marker implanted in a moving target, the onboard imaging device can capture the motion. The TrackBeam workstation processes the online MV fluence and detects and predicts tumor motion. The DmMLC system then dynamically repositions each leaf to form new beam apertures based on the movement of the fiducial marker. In this study, a dynamic phantom was used for the measurements. Three delivery patterns were evaluated for dosimetric verification based on radiographic films: no-motion lung-tumor (NMLT), three-dimensional conformal radiotherapy (3DCRT), and four-dimensional tracking radiotherapy (4DTRT). The displacement between the DmMLC dynamic beam isocenter and the fiducial marker was in the range of 0.5 mm to 1.5 mm. With radiographic film analysis, the planar dose histogram difference between 3DCRT and NLMT was 48.6% and 38.0% with dose difference tolerances of 10% and 20%, respectively. The planar dose histogram difference between 4DTRT and NLMT was 15.2% and 4.0%, respectively. Based on dose volume histogram analysis, 4DTRT reduces the mean dose for the surrounding tissue from 35.4 Gy to 19.5 Gy, reduces the relative volume of the total lung from 28% to 18% at V20, and reduces the amount of dose from 35.2 Gy to 15.0 Gy at D20. The experimental results show that MLC-based real-time beam tracking delivery provides a potential solution to respiratory motion control. Beam tracking delivers a highly conformal dose to a moving target, while sparing surrounding normal tissue.

Original languageEnglish (US)
Pages (from-to)21-33
Number of pages13
JournalJournal of Applied Clinical Medical Physics
Volume10
Issue number2
StatePublished - 2009

Fingerprint

Particle beam tracking
Radiotherapy
radiation therapy
delivery
Fiducial Markers
Tumors
dosage
collimators
histograms
X-Ray Film
markers
lungs
Tissue
tumors
Imaging techniques
workstations
Lung
Electric potential
Motion control
Conformal Radiotherapy

Keywords

  • Beam tracking
  • Dual-layer MLC
  • Fiducial marker
  • Respiratory motion

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Radiation
  • Instrumentation

Cite this

@article{88599d6d95c24d678a684d971061c231,
title = "Delivery of four-dimensional radiotherapy with TrackBeam for moving target using a dual-layer MLC: Dynamic phantoms study",
abstract = "Respiratory motion has been considered a clinical challenge for lung tumor treatments due to target motion. In this study, we aimed to perform an experimental evaluation based on dynamic phantoms using MLC-based beam tracking. TrackBeam, a prototype real-time beam tracking system, has been assembled and evaluated in our clinic. TrackBeam includes an orthogonal dual-layer micro multileaf collimator (DmMLC), an on-board mega-voltage (MV) portal imaging device, and an image processing workstation. With a fiducial marker implanted in a moving target, the onboard imaging device can capture the motion. The TrackBeam workstation processes the online MV fluence and detects and predicts tumor motion. The DmMLC system then dynamically repositions each leaf to form new beam apertures based on the movement of the fiducial marker. In this study, a dynamic phantom was used for the measurements. Three delivery patterns were evaluated for dosimetric verification based on radiographic films: no-motion lung-tumor (NMLT), three-dimensional conformal radiotherapy (3DCRT), and four-dimensional tracking radiotherapy (4DTRT). The displacement between the DmMLC dynamic beam isocenter and the fiducial marker was in the range of 0.5 mm to 1.5 mm. With radiographic film analysis, the planar dose histogram difference between 3DCRT and NLMT was 48.6{\%} and 38.0{\%} with dose difference tolerances of 10{\%} and 20{\%}, respectively. The planar dose histogram difference between 4DTRT and NLMT was 15.2{\%} and 4.0{\%}, respectively. Based on dose volume histogram analysis, 4DTRT reduces the mean dose for the surrounding tissue from 35.4 Gy to 19.5 Gy, reduces the relative volume of the total lung from 28{\%} to 18{\%} at V20, and reduces the amount of dose from 35.2 Gy to 15.0 Gy at D20. The experimental results show that MLC-based real-time beam tracking delivery provides a potential solution to respiratory motion control. Beam tracking delivers a highly conformal dose to a moving target, while sparing surrounding normal tissue.",
keywords = "Beam tracking, Dual-layer MLC, Fiducial marker, Respiratory motion",
author = "Yaxi Liu and Chengyu Shi and Bryan Lin and Ha, {Chul S} and Nikos Papanikolaou",
year = "2009",
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T1 - Delivery of four-dimensional radiotherapy with TrackBeam for moving target using a dual-layer MLC

T2 - Dynamic phantoms study

AU - Liu, Yaxi

AU - Shi, Chengyu

AU - Lin, Bryan

AU - Ha, Chul S

AU - Papanikolaou, Nikos

PY - 2009

Y1 - 2009

N2 - Respiratory motion has been considered a clinical challenge for lung tumor treatments due to target motion. In this study, we aimed to perform an experimental evaluation based on dynamic phantoms using MLC-based beam tracking. TrackBeam, a prototype real-time beam tracking system, has been assembled and evaluated in our clinic. TrackBeam includes an orthogonal dual-layer micro multileaf collimator (DmMLC), an on-board mega-voltage (MV) portal imaging device, and an image processing workstation. With a fiducial marker implanted in a moving target, the onboard imaging device can capture the motion. The TrackBeam workstation processes the online MV fluence and detects and predicts tumor motion. The DmMLC system then dynamically repositions each leaf to form new beam apertures based on the movement of the fiducial marker. In this study, a dynamic phantom was used for the measurements. Three delivery patterns were evaluated for dosimetric verification based on radiographic films: no-motion lung-tumor (NMLT), three-dimensional conformal radiotherapy (3DCRT), and four-dimensional tracking radiotherapy (4DTRT). The displacement between the DmMLC dynamic beam isocenter and the fiducial marker was in the range of 0.5 mm to 1.5 mm. With radiographic film analysis, the planar dose histogram difference between 3DCRT and NLMT was 48.6% and 38.0% with dose difference tolerances of 10% and 20%, respectively. The planar dose histogram difference between 4DTRT and NLMT was 15.2% and 4.0%, respectively. Based on dose volume histogram analysis, 4DTRT reduces the mean dose for the surrounding tissue from 35.4 Gy to 19.5 Gy, reduces the relative volume of the total lung from 28% to 18% at V20, and reduces the amount of dose from 35.2 Gy to 15.0 Gy at D20. The experimental results show that MLC-based real-time beam tracking delivery provides a potential solution to respiratory motion control. Beam tracking delivers a highly conformal dose to a moving target, while sparing surrounding normal tissue.

AB - Respiratory motion has been considered a clinical challenge for lung tumor treatments due to target motion. In this study, we aimed to perform an experimental evaluation based on dynamic phantoms using MLC-based beam tracking. TrackBeam, a prototype real-time beam tracking system, has been assembled and evaluated in our clinic. TrackBeam includes an orthogonal dual-layer micro multileaf collimator (DmMLC), an on-board mega-voltage (MV) portal imaging device, and an image processing workstation. With a fiducial marker implanted in a moving target, the onboard imaging device can capture the motion. The TrackBeam workstation processes the online MV fluence and detects and predicts tumor motion. The DmMLC system then dynamically repositions each leaf to form new beam apertures based on the movement of the fiducial marker. In this study, a dynamic phantom was used for the measurements. Three delivery patterns were evaluated for dosimetric verification based on radiographic films: no-motion lung-tumor (NMLT), three-dimensional conformal radiotherapy (3DCRT), and four-dimensional tracking radiotherapy (4DTRT). The displacement between the DmMLC dynamic beam isocenter and the fiducial marker was in the range of 0.5 mm to 1.5 mm. With radiographic film analysis, the planar dose histogram difference between 3DCRT and NLMT was 48.6% and 38.0% with dose difference tolerances of 10% and 20%, respectively. The planar dose histogram difference between 4DTRT and NLMT was 15.2% and 4.0%, respectively. Based on dose volume histogram analysis, 4DTRT reduces the mean dose for the surrounding tissue from 35.4 Gy to 19.5 Gy, reduces the relative volume of the total lung from 28% to 18% at V20, and reduces the amount of dose from 35.2 Gy to 15.0 Gy at D20. The experimental results show that MLC-based real-time beam tracking delivery provides a potential solution to respiratory motion control. Beam tracking delivers a highly conformal dose to a moving target, while sparing surrounding normal tissue.

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