Real‐time automatic fiducial marker tracking in low contrast cine‐MV images

Lin, Wei-Yang; Lin, Shu‐Fang; Yang, Sheng-Chang; Liou, Shu-Cheng; Nath, Ravinder; Liu, Wu

doi:10.1118/1.4771931

Cited by 20 publications

(36 citation statements)

References 48 publications

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“…A variety of methods for detecting and quantifying intratreatment motion have been developed, including those that rely on the implantation of radiofrequency beacons (1–4) and those that are based on the imaging of bony anatomy or implanted radiopaque fiducials. (5–14) For the most part, image-based intratreatment motion detection has been studied using MV or on-board (i.e., gantry-mounted) kilovoltage (kV) single-source systems (6,9,11) or external (i.e., room-mounted) dual-kV source systems. (5,13,14) Although kV systems provide high-quality images, current capabilities related to image acquisition frequency and directionality of the images can limit three-dimensional motion detection, either because the imaging system consists of a single kV source orthogonal to the MV beam direction (as is the case for accelerator on-board systems) or because the patient field of view may periodically be occluded by the accelerator itself (for external dual-source systems).…”

Section: Introductionmentioning

confidence: 99%

Simultaneous MV‐kV imaging for intrafractional motion management during volumetric‐modulated arc therapy delivery*

Hunt

Sonnick

Pham

et al. 2016

J Applied Clin Med Phys

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The purpose of this study was to evaluate the accuracy and clinical feasibility of a motion monitoring method employing simultaneously acquired MV and kV images during volumetric-modulated arc therapy (VMAT). Short-arc digital tomosynthesis (SA-DTS) is used to improve the quality of the MV images that are then combined with orthogonally acquired kV images to assess 3D motion. An anthropomorphic phantom with implanted gold seeds was used to assess accuracy of the method under static, typical prostatic, and respiratory motion scenarios. Automatic registration of kV images and single MV frames or MV SA-DTS reconstructed with arc lengths from 2° to 7° with the appropriate reference fiducial template images was performed using special purpose-built software. Clinical feasibility was evaluated by retrospectively analyzing images acquired over four or five sessions for each of three patients undergoing hypofractionated prostate radiotherapy. The standard deviation of the registration error in phantom using MV SA-DTS was similar to single MV images for the static and prostate motion scenarios (σ = 0.25 mm). Under respiratory motion conditions, the standard deviation of the registration error increased to 0.7mm and 1.7 mm for single MV and MV SA-DTS, respectively. Registration failures were observed with the respiratory scenario only and were due to motion-induced fiducial blurring. For the three patients studied, the mean and standard deviation of the difference between automatic registration using 4° MV SA-DTS and manual registration using single MV images results was 0.07±0.52mm. The MV SA-DTS results in patients were, on average, superior to single-frame MV by nearly 1 mm — significantly more than what was observed in phantom. The best MV SA-DTS results were observed with arc lengths of 3° to 4°. Registration failures in patients using MV SA-DTS were primarily due to blockage of the gold seeds by the MLC. The failure rate varied from 2% to 16%. Combined MV SA-DTS and kV imaging is feasible for intratreatment motion monitoring during VMAT of anatomic sites where limited motion is expected, and improves registration accuracy compared to single MV/kV frames. To create a clinically robust technique, further improvements to ensure visualization of fiducials at the desired control points without degradation of the treatment plan are needed.

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Section: Introductionmentioning

confidence: 99%

Simultaneous MV‐kV imaging for intrafractional motion management during volumetric‐modulated arc therapy delivery*

Hunt

Sonnick

Pham

et al. 2016

J Applied Clin Med Phys

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“…However, the inability of cross-correlation to match objects in a source image that are either a different size or rotated compared to the template is still one of the shortcomings in the rotation-and shift (scale)-invariant method for the object detection system [26,30,42-44]. …”

Section: Methodsmentioning

confidence: 99%

Intelligent neonatal monitoring based on a virtual thermal sensor

Abbas

Leonhardt

2014

BMC Med Imaging

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BackgroundTemperature measurement is a vital part of daily neonatal care. Accurate measurements are important for detecting deviations from normal values for both optimal incubator and radiant warmer functioning. The purpose of monitoring the temperature is to maintain the infant in a thermoneutral environmental zone. This physiological zone is defined as the narrow range of environmental temperatures in which the infant maintains a normal body temperature without increasing his or her metabolic rate and thus oxygen consumption. Although the temperature measurement gold standard is the skin electrode, infrared thermography (IRT) should be considered as an effortless and reliable tool for measuring and mapping human skin temperature distribution and assist in assessing thermoregulatory reflexes.MethodsBody surface temperature was recorded under several clinical conditions using an infrared thermography imaging technique. Temperature distributions were recorded as real-time video, which was analyzed to evaluate mean skin temperatures. Emissivity variations were considered for optimal neonatal IRT correction for which the compensation vector was overlaid on the tracking algorithm to improve the temperature reading. Finally, a tracking algorithm was designed for active follow-up of the defined region of interest over a neonate’s geometry.ResultsThe outcomes obtained from the thermal virtual sensor demonstrate its ability to accurately track different geometric profiles and shapes over the external anatomy of a neonate. Only a small percentage of the motion detection attempts failed to fit tracking scenarios due to the lack of a properly matching matrix for the ROI profile over neonate’s body surface.ConclusionsThis paper presents the design and implementation of a virtual temperature sensing application that can assist neonatologists in interpreting a neonate’s skin temperature patterns. Regarding the surface temperature, the influence of different environmental conditions inside the incubator has been confirming.

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“…Gantry‐mounted MV and kV imaging systems have been the primary equipment deployed to detect the tumor or implanted fiducials during delivery. Although significant progress has been made in tracking implanted fiducials, technical transfer from research laboratory to routine clinic has met resistance, often due to concerns of the morbidity associated with the implantation of fiducials . Directly localizing tumors without the implanted fiducials is more desirable and remains the ultimate goal .…”

Section: Introductionmentioning

confidence: 99%

Design and validation of a MV/kV imaging‐based markerless tracking system for assessing real‐time lung tumor motion

et al. 2018

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Purpose: Localizing lung tumors during treatment delivery is critical for managing respiratory motion, ensuring tumor coverage, and reducing toxicities. The purpose of this project is to develop a real-time system that performs markerless tracking of lung tumors using simultaneously acquired MV and kV images during radiotherapy of lung cancer with volumetric modulated arc therapy. Method: Continuous MV/kV images were simultaneously acquired during dose delivery. In the subsequent analysis, a gantry angle-specific region of interest was defined according to the treatment aperture. After removing imaging artifacts, processed MV/kV images were directly registered to the corresponding daily setup cone-beam CT (CBCT) projections that served as reference images. The registration objective function consisted of a sum of normalized cross-correlation, weighted by the contrast-to-noise ratio of each MV and kV image. The calculated 3D shifts of the tumor were corrected by the displacements between the CBCT projections and the planning respiratory correlated CT (RCCT) to generate motion traces referred to a specific respiratory phase. The accuracy of the algorithm was evaluated on both anthropomorphic phantom and patient studies. The phantom consisted of localizing a 3D printed tumor, embedded in a thorax phantom, in an arc delivery. In an IRB-approved study, data were obtained from VMAT treatments of two lung cancer patients with three electromagnetic (Calypso) beacon transponders implanted in airways near the lung tumor. Result: In the phantom study, the root mean square error (RMSE) between the registered and actual (programmed couch movement) target position was 1.2 mm measured by the MV/kV imaging system, which was smaller compared to the MV or kV alone, of 4.1 and 1.3 mm, respectively. In the patient study, the mean and standard deviation discrepancy between electromagnetic-based tumor position and the MV/KV-markerless approach was –0.2 ± 0.6 mm, 0.2 ± 1.0 mm, and – 1.2 ± 1.5 mm along the superior-inferior, anterior-posterior, and left-right directions, respectively; resulting in a 3D displacement discrepancy of 2.0 ± 1.1 mm. Poor contrast around the tumor was the main contribution to registration uncertainties. Conclusion: The combined MV/kV imaging system can provide real-time 3D localization of lung tumor, with comparable accuracy to the electromagnetic-based system when features of tumors are detectable. Careful design of a registration algorithm and a VMAT plan that maximizes the tumor visibility are key elements for a successful MV/KV localization strategy.

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Real‐time automatic fiducial marker tracking in low contrast cine‐MV images

Cited by 20 publications

References 48 publications

Simultaneous MV‐kV imaging for intrafractional motion management during volumetric‐modulated arc therapy delivery*

Simultaneous MV‐kV imaging for intrafractional motion management during volumetric‐modulated arc therapy delivery*

Intelligent neonatal monitoring based on a virtual thermal sensor

Design and validation of a MV/kV imaging‐based markerless tracking system for assessing real‐time lung tumor motion

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