Residual motion of lung tumors in end-of-inhale respiratory gated radiotherapy based on external surrogates

Ross I. Berbeco, Seiko Nishioka, Hiroki Shirato, Steve B. Jiang

Research output: Contribution to journalArticle

53 Citations (Scopus)

Abstract

It has been noted that some lung tumors exhibit large periodic motion due to respiration. To limit the amount of dose to healthy lung tissues, many clinics have begun gating radiotherapy treatment using externally placed surrogates. It has been observed by several institutions that the end-of-exhale (EOE) tumor position is more reproducible than other phases of the breathing cycle, so the gating window is often set there. From a treatment planning perspective, end-of-inhale (EOI) phase might be preferred for gating because the expanded lungs will further decrease the healthy tissue within the treatment field. We simulate gated treatment at the EOI phase, using a set of recently measured internal/external anatomy patient data. This paper attempts to answer three questions: (1) How much is the tumor residual motion when we use an external surrogate gating window at EOI? (2) How could we reduce the residual motion in the EOI gating window? (3) Is there a preference for amplitude- versus phase-based gating at EOI? We found that under free breathing conditions the residual motion of the tumors is much larger for EOI phase than for EOE phase. The mean values of residual motion at EOI were found to be 2.2 and 2.7 mm for amplitude- and phase-based gating, respectively, and, at EOE, 1.0 and 1.2 mm for amplitude- and phase-based gating, respectively. However, we note that the residual motion in the EOI gating window is correlated well with the reproducibility of the external surface position in the EOI phase. Using the results of a published breath-coaching study, we deduce that the residual motion of a lung tumor at EOI would approach that at EOE, with the same duty cycle (30%), under breath-coaching conditions. Additionally, we found that under these same conditions, phase-based gating approaches the same residual motion as amplitude-based gating, going from a 28% difference to 11%, for the patient with the largest difference between the two gating modalities. We conclude that it is feasible to achieve the same reproducibility of tumor location at EOI as at EOE if breath coaching is implemented, enabling us to reap the benefits of the dosimetric advantage of EOI gating.

Original languageEnglish (US)
Pages (from-to)4149-4156
Number of pages8
JournalMedical Physics
Volume33
Issue number11
DOIs
StatePublished - 2006

Fingerprint

Radiotherapy
Lung
Neoplasms
Respiration
Residual Neoplasm
Therapeutics
Anatomy
Mentoring

Keywords

  • Breath coaching
  • Gating
  • Organ motion
  • Radiotherapy
  • Residual motion

ASJC Scopus subject areas

  • Biophysics

Cite this

Residual motion of lung tumors in end-of-inhale respiratory gated radiotherapy based on external surrogates. / Berbeco, Ross I.; Nishioka, Seiko; Shirato, Hiroki; Jiang, Steve B.

In: Medical Physics, Vol. 33, No. 11, 2006, p. 4149-4156.

Research output: Contribution to journalArticle

Berbeco, Ross I. ; Nishioka, Seiko ; Shirato, Hiroki ; Jiang, Steve B. / Residual motion of lung tumors in end-of-inhale respiratory gated radiotherapy based on external surrogates. In: Medical Physics. 2006 ; Vol. 33, No. 11. pp. 4149-4156.
@article{ed64cf3fca0b4464a1dabee362218370,
title = "Residual motion of lung tumors in end-of-inhale respiratory gated radiotherapy based on external surrogates",
abstract = "It has been noted that some lung tumors exhibit large periodic motion due to respiration. To limit the amount of dose to healthy lung tissues, many clinics have begun gating radiotherapy treatment using externally placed surrogates. It has been observed by several institutions that the end-of-exhale (EOE) tumor position is more reproducible than other phases of the breathing cycle, so the gating window is often set there. From a treatment planning perspective, end-of-inhale (EOI) phase might be preferred for gating because the expanded lungs will further decrease the healthy tissue within the treatment field. We simulate gated treatment at the EOI phase, using a set of recently measured internal/external anatomy patient data. This paper attempts to answer three questions: (1) How much is the tumor residual motion when we use an external surrogate gating window at EOI? (2) How could we reduce the residual motion in the EOI gating window? (3) Is there a preference for amplitude- versus phase-based gating at EOI? We found that under free breathing conditions the residual motion of the tumors is much larger for EOI phase than for EOE phase. The mean values of residual motion at EOI were found to be 2.2 and 2.7 mm for amplitude- and phase-based gating, respectively, and, at EOE, 1.0 and 1.2 mm for amplitude- and phase-based gating, respectively. However, we note that the residual motion in the EOI gating window is correlated well with the reproducibility of the external surface position in the EOI phase. Using the results of a published breath-coaching study, we deduce that the residual motion of a lung tumor at EOI would approach that at EOE, with the same duty cycle (30{\%}), under breath-coaching conditions. Additionally, we found that under these same conditions, phase-based gating approaches the same residual motion as amplitude-based gating, going from a 28{\%} difference to 11{\%}, for the patient with the largest difference between the two gating modalities. We conclude that it is feasible to achieve the same reproducibility of tumor location at EOI as at EOE if breath coaching is implemented, enabling us to reap the benefits of the dosimetric advantage of EOI gating.",
keywords = "Breath coaching, Gating, Organ motion, Radiotherapy, Residual motion",
author = "Berbeco, {Ross I.} and Seiko Nishioka and Hiroki Shirato and Jiang, {Steve B.}",
year = "2006",
doi = "10.1118/1.2358197",
language = "English (US)",
volume = "33",
pages = "4149--4156",
journal = "Medical Physics",
issn = "0094-2405",
publisher = "AAPM - American Association of Physicists in Medicine",
number = "11",

}

TY - JOUR

T1 - Residual motion of lung tumors in end-of-inhale respiratory gated radiotherapy based on external surrogates

AU - Berbeco, Ross I.

AU - Nishioka, Seiko

AU - Shirato, Hiroki

AU - Jiang, Steve B.

PY - 2006

Y1 - 2006

N2 - It has been noted that some lung tumors exhibit large periodic motion due to respiration. To limit the amount of dose to healthy lung tissues, many clinics have begun gating radiotherapy treatment using externally placed surrogates. It has been observed by several institutions that the end-of-exhale (EOE) tumor position is more reproducible than other phases of the breathing cycle, so the gating window is often set there. From a treatment planning perspective, end-of-inhale (EOI) phase might be preferred for gating because the expanded lungs will further decrease the healthy tissue within the treatment field. We simulate gated treatment at the EOI phase, using a set of recently measured internal/external anatomy patient data. This paper attempts to answer three questions: (1) How much is the tumor residual motion when we use an external surrogate gating window at EOI? (2) How could we reduce the residual motion in the EOI gating window? (3) Is there a preference for amplitude- versus phase-based gating at EOI? We found that under free breathing conditions the residual motion of the tumors is much larger for EOI phase than for EOE phase. The mean values of residual motion at EOI were found to be 2.2 and 2.7 mm for amplitude- and phase-based gating, respectively, and, at EOE, 1.0 and 1.2 mm for amplitude- and phase-based gating, respectively. However, we note that the residual motion in the EOI gating window is correlated well with the reproducibility of the external surface position in the EOI phase. Using the results of a published breath-coaching study, we deduce that the residual motion of a lung tumor at EOI would approach that at EOE, with the same duty cycle (30%), under breath-coaching conditions. Additionally, we found that under these same conditions, phase-based gating approaches the same residual motion as amplitude-based gating, going from a 28% difference to 11%, for the patient with the largest difference between the two gating modalities. We conclude that it is feasible to achieve the same reproducibility of tumor location at EOI as at EOE if breath coaching is implemented, enabling us to reap the benefits of the dosimetric advantage of EOI gating.

AB - It has been noted that some lung tumors exhibit large periodic motion due to respiration. To limit the amount of dose to healthy lung tissues, many clinics have begun gating radiotherapy treatment using externally placed surrogates. It has been observed by several institutions that the end-of-exhale (EOE) tumor position is more reproducible than other phases of the breathing cycle, so the gating window is often set there. From a treatment planning perspective, end-of-inhale (EOI) phase might be preferred for gating because the expanded lungs will further decrease the healthy tissue within the treatment field. We simulate gated treatment at the EOI phase, using a set of recently measured internal/external anatomy patient data. This paper attempts to answer three questions: (1) How much is the tumor residual motion when we use an external surrogate gating window at EOI? (2) How could we reduce the residual motion in the EOI gating window? (3) Is there a preference for amplitude- versus phase-based gating at EOI? We found that under free breathing conditions the residual motion of the tumors is much larger for EOI phase than for EOE phase. The mean values of residual motion at EOI were found to be 2.2 and 2.7 mm for amplitude- and phase-based gating, respectively, and, at EOE, 1.0 and 1.2 mm for amplitude- and phase-based gating, respectively. However, we note that the residual motion in the EOI gating window is correlated well with the reproducibility of the external surface position in the EOI phase. Using the results of a published breath-coaching study, we deduce that the residual motion of a lung tumor at EOI would approach that at EOE, with the same duty cycle (30%), under breath-coaching conditions. Additionally, we found that under these same conditions, phase-based gating approaches the same residual motion as amplitude-based gating, going from a 28% difference to 11%, for the patient with the largest difference between the two gating modalities. We conclude that it is feasible to achieve the same reproducibility of tumor location at EOI as at EOE if breath coaching is implemented, enabling us to reap the benefits of the dosimetric advantage of EOI gating.

KW - Breath coaching

KW - Gating

KW - Organ motion

KW - Radiotherapy

KW - Residual motion

UR - http://www.scopus.com/inward/record.url?scp=33750545795&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33750545795&partnerID=8YFLogxK

U2 - 10.1118/1.2358197

DO - 10.1118/1.2358197

M3 - Article

C2 - 17153393

AN - SCOPUS:33750545795

VL - 33

SP - 4149

EP - 4156

JO - Medical Physics

JF - Medical Physics

SN - 0094-2405

IS - 11

ER -