The potential clinical benefit of respiratory gated radiotherapy (RGRT) in non-small cell lung cancer (NSCLC)

Muirhead, R.; Featherstone, C.; Duffton, A.; Moore, Karen; McNee, S.G.

doi:10.1016/j.radonc.2010.02.002

Cited by 36 publications

(39 citation statements)

References 24 publications

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“…In fixed-duty cycle experiments, the efficacy of duty cycles ranging from 20% to 50% have been studied. 1,9,11,15,21,22,24,[26][27][28] In experiments with fixed gating windows, duty cycles ranging from 12.2% to 69% have been seen. 4,7,8,17,20 Various studies have sought to improve the performance of respiratory gating by provid-ing audio or visual coaching to patients so as to increase the reproducibility and stability of their breathing patterns, especially while the tumor is in the gating window.…”

Section: Introductionmentioning

confidence: 98%

“…21 One study showed little difference between phase-based and amplitude-based gating. 19 Gating windows are often defined about the most extreme positions in the breathing cycle: 9 The end-of-exhalation ͑EOE͒ and the end-of-inhalation ͑EOI͒. EOE is chosen more often 7,10,[15][16][17]20,[22][23][24] and is more effective 4 because EOE has longer duration and slower tumor motion.…”

Section: Introductionmentioning

confidence: 99%

“…EOE is chosen more often 7,10,[15][16][17]20,[22][23][24] and is more effective 4 because EOE has longer duration and slower tumor motion. 8,9,16,25 In addition, the position of the EOE window is more reproducible. 3,19,20,25,26 EOI gating is often used with a breath-hold technique ͑deep-inspiration breath-hold͒ to increase reproducibility and stability.…”

Section: Introductionmentioning

confidence: 99%

“…3,19,20,25,26 EOI gating is often used with a breath-hold technique ͑deep-inspiration breath-hold͒ to increase reproducibility and stability. 5,26,27 EOI gating has the advantage of lower lung toxicity to surrounding normal tissue than EOE gating; 2,8,9,19,25,26 however, EOI gating has more residual motion than EOE gating. 19 One metric for evaluating respiratory gating is the duty cycle, which is the fraction of total treatment time during which radiation is being delivered.…”

Section: Introductionmentioning

confidence: 99%

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Dynamic gating window for compensation of baseline shift in respiratory‐gated radiation therapy

Pepin

Shirato

2011

Medical Physics

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Purpose: To analyze and evaluate the necessity and use of dynamic gating techniques for compensation of baseline shift during respiratory-gated radiation therapy of lung tumors. Methods: Motion tracking data from 30 lung tumors over 592 treatment fractions were analyzed for baseline shift. The finite state model ͑FSM͒ was used to identify the end-of-exhale ͑EOE͒ breathing phase throughout each treatment fraction. Using duty cycle as an evaluation metric, several methods of end-of-exhale dynamic gating were compared: An a posteriori ideal gating window, a predictive trend-line-based gating window, and a predictive weighted point-based gating window. These methods were evaluated for each of several gating window types: Superior/inferior ͑SI͒ gating, anterior/posterior beam, lateral beam, and 3D gating. Results: In the absence of dynamic gating techniques, SI gating gave a 39.6% duty cycle. The ideal SI gating window yielded a 41.5% duty cycle. The weight-based method of dynamic SI gating yielded a duty cycle of 36.2%. The trend-line-based method yielded a duty cycle of 34.0%. Conclusions: Dynamic gating was not broadly beneficial due to a breakdown of the FSM's ability to identify the EOE phase. When the EOE phase was well defined, dynamic gating showed an improvement over static-window gating.

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dynamic gating window for compensation of baseline shift in respiratory‐gated radiation therapy

Pepin

Shirato

2011

Medical Physics

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“…3,10,11 The reproducibility of the EOE phase 11,12 is aided by its long duration compared to the inhalation peak and the slowness of tumor motion within the phase. 2,12 However, the reproducibility of EOE gating is still hindered by the phenomenon of baseline-shift, 8,11,13 in which the intrafraction motion of the EOE tumor position renders the predefined gating window inaccurate.…”

Section: Introductionmentioning

confidence: 99%

Use of dMLC for implementation of dynamic respiratory‐gated radiation therapy

Pepin

Shirato

2013

Medical Physics

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Purpose:To simulate and evaluate the use of dynamic multileaf collimators (dMLC) in respiratory gating to compensate for baseline drift. Methods: Tumor motion tracking data from 30 lung tumors over 322 treatment fractions was analyzed with the finite state model. A dynamic respiratory gating window was established in real-time by determining the average positions during the previous two end-of-expiration breathing phases and centering the dMLC aperture on a weighted average of these positions. A simulated dMLC with physical motion constraints was used in dynamic gating treatment simulations. Fluence maps were created to provide a statistical description of radiation delivery for each fraction. Duty cycle was also calculated for each fraction. Results: The average duty cycle was 2.3% greater under dynamic gating conditions. Dynamic gating also showed higher fluences and less tumor obstruction. Additionally, dynamic gating required fewer beam toggles and each delivery period was longer on average than with static gating. Conclusions: The use of dynamic gating showed better performance than static gating and the physical constraints of a dMLC were shown to not be an impediment to dynamic gating.

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