Accuracy and efficiency of respiratory gating comparable to deep inspiration breath hold for pancreatic cancer treatment

Abstract

Purpose: Deep inspiration breath hold (DIBH) and respiratory gating (RG) are widely used to reduce movement of target and healthy organs caused by breathing during irradiation. We hypothesized that accuracy and efficiency comparable to DIBH can be achieved with RG for pancreas treatment.Methods and Materials: Twenty consecutive patients with pancreatic cancer treated with DIBH (eight) or RG (twelve) volumetric modulated arc therapy during 2017-2019 were included in this study, with radiopaque markers implanted near or in the targets.Seventeen patients received 25 fractions, while the other three received 15 fractions.Only patients who could not tolerate DIBH received RG treatment. While both techniques relied on respiratory signals from external markers, internal target motions were monitored with kV X-ray imaging during treatment. A 3-mm external gating window was used for DIBH treatment; RG treatment was centered on end-expiration with a duty cycle of 40%, corresponding to an external gating window of 2-3 mm. During dose delivery, kV images were automatically taken every 20 • or 40 • gantry rotation, from which internal markers were identified. The marker displacement from their initial positions and the residual motion amplitudes were calculated. For the analysis of treatment efficiency, the treatment time of every session was calculated from the motion management waveform files recorded at the treatment console.Results: Within one fraction, the displacement was 0-5 mm for DIBH and 0-6 mm for RG. The average magnitude of displacement for each patient during the entire course of treatment ranged 0-3 mm for both techniques. No statistically significant difference in displacement or residual motion was observed between the two techniques. The average treatment time was 15 min for DIBH and 17 min for RG, with no statistical significance. Conclusions:The accuracy and efficiency were comparable between RG and DIBH treatment for pancreas irradiation. RG is a feasible alternative strategy to DIBH.

Stereotactic Body Radiotherapy (SBRT) of Pancreatic Cancer—A Critical Review and Practical Consideration

“…This shift goes hand in hand with technological developments that enable the delivery of a highly focused radiation dose to the tumor while sparing the adjacent at-risk organs, especially gastrointestinal (GI) structures. These methods include most of the following: targeting radiation beams to fiducials or markers inserted into the tumor [ 19 ], daily use of a computed tomography (CT) device on a linear accelerator platform (cone beam computed tomography, CBCT) [ 20 ], management of breathing movements during simulation [ 21 ], treatment alone (deep inspiration breath hold, DIBH), rapid and accurate dose administration (volumetric modulated arc therapy, VMAT) [ 22 ], the use of high-dose-rate beams without homogenization filters (flattening filter free, FFF) [ 23 ], or the possibility of correcting and optimizing the patient’s position by employing the irradiation table with six degrees of freedom [ 24 ].…”

Automatic stent recognition using perceptual attention U‐net for quantitative intrafraction motion monitoring in pancreatic cancer radiotherapy

“…However, recent studies revealed potentially poor correlations between the motion of external surrogates and internal surrogates (for instance, fiducial, surgical clip, and intrabiliary stent) in DIBH and gated pancreatic cancer radiotherapy. 17,18 Due to the proximity and motion pattern similarity to the tumor, internal radiopaque markers-based motion management techniques have enhanced the confidence in delivering high doses of radiation close to critical structures with precision. The stent has been used regularly as a standard internal surrogate for pancreatic cancer radiotherapy to monitor intrafraction tumor motion during pancreatic cancer radiotherapy, with reliable tumor localization.…”

“…It uses the stent contours generated from the treatment plan and has limited quantitative motion information. 17,18 Studies on similar systems, such as active breathing coordination (ABC, Elekta, Stockholm, Sweden), warrant quantitative intrafraction motion management. 19 Segmenting stent automatically from X-ray projection images is more challenging than segmentation in the CT/MR image domain with high image contrast, a piecewise image property, and well-defined spatial information in three-dimensional space.…”

“…Deep inspiration breath hold (DIBH) or gating technique with real‐time position management or respiratory gating for scanners (RGSC, Varian Medical Systems, Palo Alto, CA, USA), which monitor the patient's respiratory motion based on the external surrogate (infrared marker blocks on the patient's skin), have been widely used to mitigate the respiratory motion effect in pancreatic cancer radiotherapy. However, recent studies revealed potentially poor correlations between the motion of external surrogates and internal surrogates (for instance, fiducial, surgical clip, and intrabiliary stent) in DIBH and gated pancreatic cancer radiotherapy 17,18 . Due to the proximity and motion pattern similarity to the tumor, internal radiopaque markers‐based motion management techniques have enhanced the confidence in delivering high doses of radiation close to critical structures with precision.…”

“…The current intrafraction motion review (IMR) system on Varian TrueBeam (Varian Medical Systems, Palo Alto, CA, USA) can only provide a tool for visual verification of the stent motion. It uses the stent contours generated from the treatment plan and has limited quantitative motion information 17,18 . Studies on similar systems, such as active breathing coordination (ABC, Elekta, Stockholm, Sweden), warrant quantitative intrafraction motion management 19 .…”