Analysis of a free‐running synchronization artifact correction for MV‐imaging with aSi:H flat panels

Mooslechner, M.; Mitterlechner, B.; Weichenberger, H.; Huber, Stefan; Sedlmayer, Felix; Deutschmann, H.

doi:10.1118/1.4790564

Cited by 7 publications

(10 citation statements)

References 30 publications

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“…Based on the results of static marker detection reported in Table I, it was shown that the detrimental effect of pulsing artifacts on marker detection success was increased in function of frame rates. This confirmed the hypothese from Mooslechner et al 20 that the effect of pulsing artifacts increases for higher frame rates like, 30 Hz on the XRD 1642 AP19. With the availability of high frame rate MV imaging, research on pulsing artifact suppression is gaining importance.…”

Section: Hzsupporting

confidence: 90%

“…With respect to the maximum field size of 15 × 15 cm 2 on the Vero system, a small line artifact was reintroduced during electronic synchronized readout for in-air open beam MV images in function of smaller field sizes. Based on quantitative evaluation using Mooslechner's SNR, 20 the field size dependent line artifact during synchronized readout was considered to be a second order image degradation effect with respect to pulsing artifacts experienced during free running MV imaging. To our knowledge, a line artifact during synchronized readout with START-STOP, that is function of the field size, was not described before in literature.…”

Section: Discussionmentioning

confidence: 99%

“…This work was sponsored by the Flemish Government through Hercules Foundation and corporate funding from BrainLab AG. a) Part of this work was presented during the AAPM annual meeting [19][20][21][22][23][24] July 2014 in Austin, TX.…”

Section: Acknowledgmentsmentioning

confidence: 99%

“…A new pulsing artifact correction method was proposed by Mooslechner et al 20 using precalculated synch patterns based on the specific PRF of the linac at the moment of acquisition. Although this synchronization method was suitable to correct the pulsing artifact for both low and high PRF values, a lookup table approach should be applied when a varying PRF was induced during irradiation.…”

Section: Introductionmentioning

confidence: 99%

“…Also the influence of pulsing artifacts on marker-less detection was not considered in the paper of Yip et al For a low dose rate delivery, like volumetric modulated arc therapy (VMAT), pulsing artifacts could be more dominant. 13,20 In this paper, it was investigated if a commercially available, new generation EPID (XRD 1642 AP19, PerkinElmer Inc., Waltham, ME) with fast (30 Hz) frame rate and a more sensitive scintillator was capable to improve detection of a MV and a non-MV compatible Visicoil™ marker. Also, the performance of MV marker-less detection for a small lung tumor was investigated on this new EPID.…”

Section: Introductionmentioning

confidence: 99%

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Fiducial marker and marker‐less soft‐tissue detection using fast MV fluoroscopy on a new generation EPID: Investigating the influence of pulsing artifacts and artifact suppression techniques

et al. 2014

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In general, marker contrast decreased in function of higher frame rates, which was detrimental for marker detection success. In this work, Visicoils with a thickness of 0.075 cm were showing best results for a 15 Hz frame rate, while non-MV compatible 0.05 cm Visicoil markers were not visible on the new EPID with improved sensitivity compared to EPID models based on a Kodak Lanex Fast scintillator. No noticeable influence of pulsing artifacts on the detection of a 0.075 cm Visicoil was observed, while a synchronized readout provided most reliable detection of a marker-less soft-tissue structure.

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Section: Hzsupporting

confidence: 90%

Section: Discussionmentioning

confidence: 99%

Section: Acknowledgmentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fiducial marker and marker‐less soft‐tissue detection using fast MV fluoroscopy on a new generation EPID: Investigating the influence of pulsing artifacts and artifact suppression techniques

et al. 2014

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Evaluation of MegaVoltage Cone Beam CT image quality with an unmodified Elekta Precise Linac and EPID: a feasibility study

Markwell

Perera

Trapp

et al. 2014

Australas Phys Eng Sci Med

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In order to increase the accuracy of patient positioning for complex radiotherapy treatments various 3D imaging techniques have been developed. MegaVoltage Cone Beam CT (MVCBCT) can utilise existing hardware to implement a 3D imaging modality to aid patient positioning. MVCBCT has been investigated using an unmodified Elekta Precise Linac and iView amorphous silicon electronic portal imaging device (EPID). Two methods of delivery and acquisition have been investigated for imaging an anthropomorphic head phantom and quality assurance phantom. Phantom projections were successfully acquired and CT datasets reconstructed using both acquisition methods. Bone, tissue and air were clearly resolvable in both phantoms even with low dose (22 MU) scans. The feasibility of MVCBCT was investigated using a standard linac, amorphous silicon EPID and a combination of a free open source reconstruction toolkit as well as custom in-house software written in Matlab. The resultant image quality has been assessed and presented. Although bone, tissue and air were resolvable in all scans, artifacts are present and scan doses are increased when compared with standard portal imaging. The feasibility of MVCBCT with unmodified Elekta Precise Linac and EPID has been considered as well as the identification of possible areas for future development in artifact correction techniques to further improve image quality.

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Use of electronic portal imaging devices for electron treatment verification

Kairn

Crowe

Trapp

2015

Australas Phys Eng Sci Med

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This study aims to help broaden the use of electronic portal imaging devices (EPIDs) for pre-treatment patient positioning verification, from photon-beam radiotherapy to photon- and electron-beam radiotherapy, by proposing and testing a method for acquiring clinically-useful EPID images of patient anatomy using electron beams, with a view to enabling and encouraging further research in this area. EPID images used in this study were acquired using all available beams from a linac configured to deliver electron beams with nominal energies of 6, 9, 12, 16 and 20 MeV, as well as photon beams with nominal energies of 6 and 10 MV. A widely-available heterogeneous, approximately-humanoid, thorax phantom was used, to provide an indication of the contrast and noise produced when imaging different types of tissue with comparatively realistic thicknesses. The acquired images were automatically calibrated, corrected for the effects of variations in the sensitivity of individual photodiodes, using a flood field image. For electron beam imaging, flood field EPID calibration images were acquired with and without the placement of blocks of water-equivalent plastic (with thicknesses approximately equal to the practical range of electrons in the plastic) placed upstream of the EPID, to filter out the primary electron beam, leaving only the bremsstrahlung photon signal. While the electron beam images acquired using a standard (unfiltered) flood field calibration were observed to be noisy and difficult to interpret, the electron beam images acquired using the filtered flood field calibration showed tissues and bony anatomy with levels of contrast and noise that were similar to the contrast and noise levels seen in the clinically acceptable photon beam EPID images. The best electron beam imaging results (highest contrast, signal-to-noise and contrast-to-noise ratios) were achieved when the images were acquired using the higher energy electron beams (16 and 20 MeV) when the EPID was calibrated using an intermediate (12 MeV) electron beam energy. These results demonstrate the feasibility of acquiring clinically-useful EPID images of patient anatomy using electron beams and suggest important avenues for future investigation, thus enabling and encouraging further research in this area. There is manifest potential for the EPID imaging method proposed in this work to lead to the clinical use of electron beam imaging for geometric verification of electron treatments in the future.

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Analysis of a free‐running synchronization artifact correction for MV‐imaging with aSi:H flat panels

Cited by 7 publications

References 30 publications

Fiducial marker and marker‐less soft‐tissue detection using fast MV fluoroscopy on a new generation EPID: Investigating the influence of pulsing artifacts and artifact suppression techniques

Fiducial marker and marker‐less soft‐tissue detection using fast MV fluoroscopy on a new generation EPID: Investigating the influence of pulsing artifacts and artifact suppression techniques

Evaluation of MegaVoltage Cone Beam CT image quality with an unmodified Elekta Precise Linac and EPID: a feasibility study

Use of electronic portal imaging devices for electron treatment verification

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