Effect of secondary particles on image quality of dynamic flat panels in carbon ion scanning beam treatment

Mori, Shinichiro; Amano, Saki; Furukawa, Takuji; Shirai, Tomoyuki; Noda, K.

doi:10.1259/bjr.20140567

Cited by 4 publications

(2 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…DFPD image acquisition without x‐ray exposure was not used for the tracking calculation to maximize image quality by cleaning up secondary particles stored during the DFPD charge process [Fig. (b)] …”

Section: Methodsmentioning

confidence: 99%

Commissioning of a fluoroscopic‐based real‐time markerless tumor tracking system in a superconducting rotating gantry for carbon‐ion pencil beam scanning treatment

Mori¹,

Sakata

Hirai

et al. 2019

Medical Physics

View full text Add to dashboard Cite

Purpose: To perform the final quality assurance of our fluoroscopic-based markerless tumor tracking for gated carbon-ion pencil beam scanning (C-PBS) radiotherapy using a rotating gantry system, we evaluated the geometrical accuracy and tumor tracking accuracy using a moving chest phantom with simulated respiration. Methods: The positions of the dynamic flat panel detector (DFPD) and x-ray tube are subject to changes due to gantry sag. To compensate for this, we generated a geometrical calibration table (gantry flex map) in 15°gantry angle steps by the bundle adjustment method. We evaluated five metrics: (a) Geometrical calibration was evaluated by calculating chest phantom positional error using 2D/3D registration software for each 5°step of the gantry angle. (b) Moving phantom displacement accuracy was measured (AE10 mm in 1-mm steps) with a laser sensor. (c) Tracking accuracy was evaluated with machine learning (ML) and multi-template matching (MTM) algorithms, which used fluoroscopic images and digitally reconstructed radiographic (DRR) images as training data. The chest phantom was continuously moved AE10 mm in a sinusoidal path with a moving cycle of 4 s and respiration was simulated with AE5 mm expansion/contraction with a cycle of 2 s. This was performed with the gantry angle set at 0°, 45°, 120°, and 240°. (d) Four types of interlock function were evaluated: tumor velocity, DFPD image brightness variation, tracking anomaly detection, and tracking positional inconsistency in between the two corresponding rays. (e) Gate on/off latency, gating control system latency, and beam irradiation latency were measured using a laser sensor and an oscilloscope. Results: By applying the gantry flex map, phantom positional accuracy was improved from 1.03 mm/0.33°to <0.45 mm/0.27°for all gantry angles. The moving phantom displacement error was 0.1 mm. Due to long computation time, the tracking accuracy achieved with ML was <0.49 mm (=95% confidence interval [CI]) for imaging rates of 15 and 7.5 fps; those at 30 fps were decreased to 1.84 mm (95% CI: 1.79 mm-1.92 mm). The tracking positional accuracy with MTM was <0.52 mm (=95% CI) for all gantry angles and imaging frame rates. The tumor velocity interlock signal delay time was 44.7 ms (=1.3 frame). DFPD image brightness interlock latency was 34 ms (=1.0 frame). The tracking positional error was improved from 2.27 AE 2.67 mm to 0.25 AE 0.24 mm by the tracking anomaly detection interlock function. Tracking positional inconsistency interlock signal was output within 5.0 ms. The gate on/off latency was <82.7 AE 7.6 ms. The gating control system latency was <3.1 AE 1.0 ms. The beam irradiation latency was <8.7 AE 1.2 ms. Conclusions: Our markerless tracking system is now ready for clinical use. We hope to shorten the computation time needed by the ML algorithm at 30 fps in the future.

show abstract

Section: Methodsmentioning

confidence: 99%

Commissioning of a fluoroscopic‐based real‐time markerless tumor tracking system in a superconducting rotating gantry for carbon‐ion pencil beam scanning treatment

Mori¹,

Sakata

Hirai

et al. 2019

Medical Physics

View full text Add to dashboard Cite

show abstract

“…The images were acquired during irradiation with the treatment beam. However, the imaging sequence was modified to suppress scattered radiation (Mori et al 2015). The size of the marker is 10.0 mm in length with a diameter of 0.4 mm.…”

Section: Experimental Conditionmentioning

confidence: 99%

Real-time nonstandard-shaped gold fiducial marker tracking on x-ray fluoroscopic images for prostate radiotherapy

Sakata,

Umene,

Asaka

et al. 2024

Phys. Med. Biol.

View full text Add to dashboard Cite

The prostate moves in accordance with the movement of surrounding organs.Tumor position can change by ≧ 3 mm during radiotherapy.Given the difficulties of visualizing the prostate fluoroscopically, fiducial markers are generally implanted into the prostate to monitor its motion during treatment.Recently, internally synchronized irradiation of the prostate using a 99.5 % gold/0.5 % iron flexible notched wire fiducial marker (Gold Anchor®, Naslund Medical AB, Huddinge, Sweden), which requires a 22 gauge needle, has been used.However, because the notched wire can retain its linear shape, acquire a spiral shape, or roll into an irregular ball, detecting it on fluoroscopic images in real-time incurs higher computation costs.We developed a fiducial tracking algorithm to achieve real-time computation.The marker is detected on the first image frame using a shape filter that employs inter-class variance for the marker likelihood calculated by the filter, focusing on the large difference in densities between the marker and its surroundings.After the second frame, the marker is tracked by adding to the shape filter the similarity to the template cropped from the area around the marker position detected in the first frame.We retrospectively evaluated the algorithm's marker tracking accuracy for ten prostate cases, analyzing two fractions in each case.Tracking positional accuracy averaged over all patients was 0.13 ± 0.04 mm (mean ± standard deviation, Euclidean distance) and 0.25 ± 0.09 mm 95th percentile).Computation time was 2.82 ± 0.20 ms/frame averaged over all frames.Our algorithm successfully detected marker position in real time.

show abstract

Modeling and Objectification of Skiagraphy Image Quality Deterioration Caused by X-Ray Secondary Irradiation on Mobile X-Ray Device

et al. 2019

View full text Add to dashboard Cite

Effect of secondary particles on image quality of dynamic flat panels in carbon ion scanning beam treatment

Abstract: This technique may be useful for markerless tumour tracking for respiratory gating.

Cited by 4 publications

References 23 publications

Commissioning of a fluoroscopic‐based real‐time markerless tumor tracking system in a superconducting rotating gantry for carbon‐ion pencil beam scanning treatment

Commissioning of a fluoroscopic‐based real‐time markerless tumor tracking system in a superconducting rotating gantry for carbon‐ion pencil beam scanning treatment

Real-time nonstandard-shaped gold fiducial marker tracking on x-ray fluoroscopic images for prostate radiotherapy

Modeling and Objectification of Skiagraphy Image Quality Deterioration Caused by X-Ray Secondary Irradiation on Mobile X-Ray Device

Contact Info

Product

Resources

About