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Lei Xing - One of the best experts on this subject based on the ideXlab platform.

  • image guided radiotherapy in near real time with intensity modulated radiotherapy megavoltage treatment beam imaging
    International Journal of Radiation Oncology Biology Physics, 2009
    Co-Authors: Nadeem Riaz, R Wiersma, Lei Xing, G Luxton, Christopher R King, T Solberg
    Abstract:

    Purpose: To utilize image-guided radiotherapy (IGRT) in near real time by obtaining and evaluating the online positions of implanted Fiducials from continuous electronic portal imaging device (EPID) imaging of prostate intensity-modulated radiotherapy (IMRT) delivery. Methodsand Materials: Uponinitial setupusingtwoorthogonal images,the three-dimensional(3D)positionsof all implanted fiducial markers are obtained, and their expected two-dimensional (2D) locations in the beam’seye-view (BEV) projection are calculated for each treatment field. During IMRT beam delivery, EPID images of the megavoltage treatment beam are acquired in cine mode and subsequently analyzed to locate 2D locations of Fiducials in the BEV. Simultaneously, 3D positions are estimated according to the current EPID image, informationfromthesetupportalimages,andimagesacquiredatothergantryangles(thecompletedtreatmentfields). The measured 2D and 3D positions of each fiducial are compared with their expected 2D and 3D setup positions, respectively. Any displacements larger than a predefined tolerance may cause the treatment system to suspend the beam delivery and direct the therapists to reposition the patient. Results: Phantom studies indicate that the accuracyof 2D BEVand 3D tracking are better than 1 mm and 1.4 mm, respectively. A total of 7330 images fromprostate treatmentswereacquiredand analyzed, showing amaximum 2D displacement of 6.7 mm and a maximum 3D displacement of 6.9 mm over 34 fractions. Conclusions: This EPID-based, real-time IGRT method can be implemented on any external beam machine with portal imaging capabilities without purchasing any additional equipment, and there is no extra dose delivered to the patient. ! 2009 Elsevier Inc. IGRT, Real-time tracking, Fiducial marker, Prostate, EPID.

  • four dimensional inverse treatment planning with inclusion of implanted Fiducials in imrt segmented fields
    Medical Physics, 2009
    Co-Authors: L Lee, O Keshet, P Keall, Lei Xing
    Abstract:

    The purpose of this study is to develop a 4D inverse planning strategy capable of controlling the appearance of the implanted fiducial(s) in segmented IMRT fields for cine MV or combined MV∕kV image-guided IMRT. This work is focused on enhancing the visibility of the implanted fiducial(s) in 4D IMRT inverse planning, whose goal is to derive a set of time-resolved (or phase-tagged) MLC segments to cater for the motion of the patient anatomy extracted from the emerging 4D images. The task is to optimize the shapes and weights of all the segments for each incident beam, with the fiducial(s) being forced∕encouraged to be inside the segmented fields. The system is modeled by a quadratic objective function with inclusion of a hard∕soft constraint characterizing the authors’ level of preference for the fiducial(s) to be included in the segmented fields. A simulated annealing algorithm is employed to optimize the system. The proposed technique is demonstrated using two clinical cases. A segment-based inverse planning framework for 4D radiation therapy, capable of providing tempospatially optimized IMRT plans, has been established. Furthermore, using the described 4D optimization approach, it is demonstrated that the MLC blockage of the implanted fiducial(s) during the segmented delivery is avoided without severely compromising the final dose distribution. The visibility of implanted Fiducials in 4D IMRT can be improved without significantly deteriorating final dose distribution. This is a foundation for the authors to use cine MV or combined MV∕KV to effectively guide the 4D IMRT delivery.

  • su ff t 155 four dimensional inverse treatment planning with inclusion of implanted Fiducials in imrt segmented fields
    Medical Physics, 2009
    Co-Authors: L Lee, P Keall, Lei Xing
    Abstract:

    Purpose: To develop a 4D inverse planning strategy capable of controlling the appearance of the implanted fiducial(s) in segmented IMRT fields for cine MV or combined MV/kV image‐guidedIMRT.Method: This work is focused on enhancing the visibility of the implanted fiducial(s) in 4D IMRT inverse planning, whose goal is to derive a set of time‐resolved (or phase‐tagged) MLC segments to cater for the motion of the patient anatomy extracted from the emerging 4D images. The task is to optimize the shapes and weights of all the segments for each incident beam, with the fiducial(s) being forced/encouraged to be inside the segmented fields. The system is modeled by a quadratic objective function with inclusion of a hard/soft constraint characterizing our level of preference for the fiducial(s) to be included in the segmented fields. A simulated annealing algorithm is employed to optimize the system. The proposed technique is demonstrated using two clinical cases. Results: A segment‐based inverse planning framework for 4D radiation therapy, capable of providing tempo‐spatially optimized IMRT plans, has been established. Furthermore, using the described 4D optimization approach, it is demonstrated that the MLC‐blockage of the implanted fiducial(s) during the segmented delivery is avoided without severely compromising the final dose distribution. Conclusions: The visibility of implanted Fiducials in 4D IMRT can be improved without significantly deteriorating find dose distribution. This is a foundation for us to use cine MV or combined MV/KV to effectively guide the 4D IMRT delivery.

  • we c 351 06 tracking multiple moving Fiducials during treatment based on simultaneous onboard kv and treatment mv imaging
    Medical Physics, 2008
    Co-Authors: W Mao, Nadeem Riaz, Kaifai Lee, R Wiersma, Lei Xing
    Abstract:

    Purpose: Intra‐fractional organ motion can limit the advantage of highly conformal dose techniques as IMRT due to target position uncertainty. A new strategy has been proposed and investigated to track implanted fiducial markers during treatment on a LINAC with an onboard kV imaging system by using simultaneous kV and treatment MV beam imaging.Method and Materials: A pelvic phantom implanted with three gold cylindrical seeds was tested on a moving platform on a Varian Trilogy. Two phantom verification plans for 3DCRT and IMRTtreatments from real patients were delivered on this phantom while the platform was moving at different speeds. A new pattern matching algorithm has been developed to locate multiple cylindrical Fiducials on MV and kV images. Their 3D positions were then calculated from simultaneous orthogonal MV and kV imaging results. Results: Four issues were studied towards the clinical application of this method. 1) Multiple methods were adopted to predict marker positions and reduce search regions to achieve an analysis speed of 10 frame/second. 2) The kV and MV images were acquired while the phantom was moving at various speeds and Fiducials could be successfully detected at a linear speed of 1.6 cm/s or less. 3) Varying MV field size and kV source to imager distance indicated that the detection of Fiducials on kV images was not affected by the scattering from simultaneous treatment MV beams. 4) Prediction based on relative positions of Fiducials was used to closely locate positions of Fiducials blocked by a multileaf collimator.Conclusion: These four studies pave the way to automatically track nearly real‐time 3D positions of multiple moving fiducial markers during treatment based on simultaneous kV and MV imaging. It does not require extra hardware such as stereo kV imaging systems and utilizes the treatment beam to reduce dose.

Eun Ji Shin - One of the best experts on this subject based on the ideXlab platform.

  • role of endoscopic ultrasonography guided fiducial marker placement in gastrointestinal cancer
    Current Opinion in Gastroenterology, 2020
    Co-Authors: Tossapol Kerdsirichairat, Eun Ji Shin
    Abstract:

    PURPOSE OF REVIEW Dose escalation radiation therapy such as those delivered by stereotactic body radiation therapy (SBRT) has shown to improve local disease control in multiple types of malignancies. This requires fiducial placement to improve accuracy of treatment and avoid adverse events to adjacent radiosensitive organs during respiration phases. The purpose of this review is to provide updates of recent high-quality articles related to endoscopic ultrasonography (EUS)-guided fiducial placement for gastrointestinal malignancies, particularly in pancreatic cancer, which is expected to be the second leading cause of cancer-related deaths in the USA within this decade. RECENT FINDINGS A recent systematic review and meta-analysis has shown that EUS-guided fiducial placement for gastrointestinal malignancies has excellent technical success and safety profile. Comparative studies of most commercially available fiducial types via a 22-gauge needle system showed that a 0.035 mm diameter and 10 mm long gold fiducial with coiled configuration, hollow core and external helical design might be favoured due to its most balanced performance of visibility, artifact and migration. SUMMARY A fine balance of performance characteristics of Fiducials should be discussed with radiation oncologists to select a suitable and preferred type of Fiducials. The comparative studies of other newly developed platinum Fiducials and liquid fiducial are pending.

  • analysis of Fiducials implanted during endoscopic ultrasound eus for locally advanced rectal cancer patients receiving high dose rate endorectal brachytherapy endo hdr
    Journal of Clinical Oncology, 2014
    Co-Authors: Shalini Moningi, Eun Ji Shin, Ashkan A Malayeri, Susan L Gearhart, Jonathan E Efron, Elizabeth C Wick, Nilofer S Azad, Luis A Diaz, Elwood P Armour, Joseph M Herman
    Abstract:

    655 Background: Rectal cancer affects over 40,000 patients in the US per year. The current standard of care for patients with localized rectal cancer is neoadjuvant radiation therapy with concurrent chemotherapy (NCRT) followed by surgery; however, it has shown no proven survival benefit for locally advanced rectal cancer patients. Preliminary results show that a short course of radiation therapy, using high-dose rate endorectal brachytherapy (Endo-HDR), may be as effective with less toxicity and delay to time of surgery. This requires the placement of fiducial markers, using an endoscopic ultrasound guided method (EUS), into the tumor for accurate source placement and treatment. Our aim is to compare three different types of Fiducials in terms of visibility and migration. Methods: 12 patients with locally advanced rectal cancer that received Endo-HDR and EUS guided fiducial placement were retrospectively evaluated at JHH. Results: 12 patients underwent EUS guided placement of 42 Fiducials. For 11 of our ...

  • comparative analysis of traditional and coiled Fiducials implanted during eus for pancreatic cancer patients receiving stereotactic body radiation therapy
    Gastrointestinal Endoscopy, 2012
    Co-Authors: Mouen A Khashab, Eun Ji Shin, Katherine Kim, E Tryggestad, Aaron T Wild, Teboh Roland, Vikesh K Singh, Anne Marie Lennon, Mark A Ziegler, Reem Z Sharaiha
    Abstract:

    Background EUS-guided fiducial placement facilitates image-guided radiation therapy (IGRT). Objective To compare 2 types of commercially available Fiducials for technical success, complications, visibility, and migration. Design Retrospective, single-center, comparative study. Setting Tertiary-care medical center. Interventions Traditional Fiducials (TFs) (5-mm length, 0.8-mm diameter) and Visicoil Fiducials (VFs) (10-mm length, 0.35-mm diameter) were compared. Fiducials were placed using linear 19-gauge (for TFs) or 22-gauge (for VFs) needles. A subjective visualization scoring system (0-2; 0=not visible, 1=barely visible, 2=clearly visible) was used to assess visibility on CT. Fiducial migration was calculated as a change in interfiducial distance. Main Outcome Measurements Technical success, complications, visibility, and migration of 2 types of Fiducials. Results Thirty-nine patients with locally advanced pancreatic cancer underwent EUS-guided placement of 103 Fiducials (77 TFs, 26 VFs). The mean number of Fiducials placed per patient was 2.66 (standard deviation 0.67) for the 19-gauge needle and 2.60 (standard deviation 0.70) for the 22-gauge needle ( P = .83). No intra- or postprocedural complications were encountered. The median visibility score for TFs was significantly better than that for VFs, both when scores of 0 were and were not included (2.00, interquartile range [IQR] 2.00-2.00 vs 1.75, IQR 1.50-2.00, P = .009 and 2.00, IQR 2.00-2.00 vs 2.00, IQR 1.50-2.00, P P = .72). Limitations Retrospective, nonrandomized design. Conclusions Visibility was significantly better for TFs compared with VFs. The degree of fiducial migration was not significantly different for TFs and VFs. There was no significant difference in the mean number of Fiducials placed, indicating a similar degree of technical difficulty for TF and VF deployment.

Rajat J Kudchadker - One of the best experts on this subject based on the ideXlab platform.

  • investigation of dose perturbations and the radiographic visibility of potential Fiducials for proton radiation therapy of the prostate
    Physics in Medicine and Biology, 2011
    Co-Authors: Rajat J Kudchadker, Ronald X Zhu, Andrew K Lee, Wayne D Newhauser, Jessie Y Huang
    Abstract:

    Image guidance using implanted fiducial markers is commonly used to ensure accurate and reproducible target positioning in radiation therapy for prostate cancer. The ideal fiducial marker is clearly visible in kV imaging, does not perturb the therapeutic dose in the target volume and does not cause any artifacts on the CT images used for treatment planning. As yet, ideal markers that fully meet all three of these criteria have not been reported. In this study, 12 fiducial markers were evaluated for their potential clinical utility in proton radiation therapy for prostate cancer. In order to identify the good candidates, each fiducial was imaged using a CT scanner as well as a kV imaging system. Additionally, the dose perturbation caused by each fiducial was quantified using radiochromic film and a clinical proton beam. Based on the results, three Fiducials were identified as good candidates for use in proton radiotherapy of prostate cancer.

  • dose perturbations and image artifacts caused by carbon coated ceramic and stainless steel Fiducials used in proton therapy for prostate cancer
    Physics in Medicine and Biology, 2010
    Co-Authors: J Cheung, Rajat J Kudchadker, Ronald X Zhu, Andrew K Lee, Wayne D Newhauser
    Abstract:

    Image-guided radiation therapy using implanted fiducial markers is a common solution for prostate localization to improve targeting accuracy. However, Fiducials that are typically used for conventional photon radiotherapy cause large dose perturbations in patients who receive proton radiotherapy. A proposed solution has been to use Fiducials of lower atomic number (Z) materials to minimize this effect in tissue, but the effects of these Fiducials on dose distributions have not been quantified. The objective of this study was to analyze the magnitude of the dose perturbations caused by select lower-Z Fiducials (a carbon-coated zirconium dioxide fiducial and a plastic-coated stainless steel fiducial) and compare them to perturbations caused by conventional gold Fiducials. Sets of phantoms were used to assess select components of the effects on dose. First, the Fiducials were assessed for radiographic visibility using both conventional computed tomography (CT) and an on-board kilovoltage imaging device at our proton therapy center. CT streak artifacts from the Fiducials were also measured in a separate phantom. Second, dose perturbations were measured downstream of the Fiducials using radiochromic film. The magnitude of dose perturbation was characterized as a function of marker material, implantation depth and orientation with respect to the beam axis. The radiographic visibility of the markers was deemed to be acceptable for clinical use. The dose measurements showed that the perpendicularly oriented zirconium dioxide and stainless steel Fiducials located near the center of modulation of the proton beam perturbed the dose by less than 10%, but that the same Fiducials in a parallel orientation near the end of the range of the beam could perturb the dose by as much as 38%. This suggests that carbon-coated and stainless steel Fiducials could be used in proton therapy if they are located far from the end of the range of the beam and if they are oriented perpendicular to the beam axis.

  • a technique for reducing patient setup uncertainties by aligning and verifying daily positioning of a moving tumor using implanted Fiducials
    Journal of Applied Clinical Medical Physics, 2008
    Co-Authors: Christopher Lee Nelson, Rajat J Kudchadker, Peter A Balter, Rodolfo C Morice, B Choi, Kara M Bucci, Joe Y Chang, Lei Dong, Susan L Tucker, Sastry Vedam
    Abstract:

    Purpose : The purpose of this study is to validate and implement a methodology in which Fiducials implanted in the periphery of lung tumors can be used to reduce uncertainties in tumor location. Methods and Materials : Alignment software that matches marker positions on two-dimensional (2D) kilovoltage portal images to positions on three-dimensional (3D) computed tomography data sets was validated using static and moving phantoms. This software also was used on a patient with Fiducials implanted in the periphery of a lung tumor to reduce uncertainties in tumor location. Results : Aligning fiducial locations in orthogonal projection images with corresponding fiducial locations in 3D data sets can be used to position both static and moving phantoms with an accuracy of 1 mm. In a patient, alignment based on fiducial locations reduced systematic errors in the left-right direction by 3 mm and random errors by 2 mm, and random errors in the superior-inferior direction by 3 mm as measured by anterior-posterior cine images. Conclusions : Software that matches fiducial markers on 2D and 3D images is effective for aligning both static and moving Fiducials prior to treatment and can be implemented to reduce patient setup uncertainties.

  • su ff j 21 a comparison of a point based tool with an image overlay tool for fiducial based setup
    Medical Physics, 2007
    Co-Authors: Peter A Balter, Tina Marie Briere, Rajat J Kudchadker, Christopher Lee Nelson, Sastry Vedam, P Lindsay, Ritsuko Komaki, Radhe Mohan
    Abstract:

    Purpose: To compare interactive image overlay tools for fiducial based setup with a point based system. Method and Materials: A single implanted fiducial was used for localization. Gated kVp images were acquired for daily setup; if a shift was made, a 2nd set of images were acquired subsequent to the shift. Shifts were determined using both a commercial software package designed for point matching (ISOLOC, CIVCO, Kalona, IA) and also by dragging the projection of the fiducial contour over the image of the fiducial using tools integrated into the treatment delivery console(4DTC, Varian, Palo Alto, CA). Data was collected for 29 shifts on 15 different days. Results: The mean magnitude of the initial shifts were 1.5, 5.7, and 1.5 mm and the means of the differences between the shifts were 0.2, 1.1 and 0.8 mm in the lateral, cranial‐caudal, and AP directions respectively. On many days there was a discrepancy of 1–2 mm between the AP and lateral gated kVp X‐rays. The interactive tools allowed the user to compromise between the two projections, while the automatic system forced a compromise. The interactive tools also displayed a projection of the tumor allowing validation of the position of the fiducial with respect to the bulk tumor. The interactive tools were quicker to use and automatically applied the shifts; these tools are somewhat limited by the accuracy of the contouring of the Fiducials. Conclusion: Both the interactive tools and the automatic system are practical for daily setup of patients with Fiducials, but the integration into the console, the speed of localization, and most importantly the ability to correlate the Fiducials with radioopaque anatomy make the interactive tools superior.

Armin Ernst - One of the best experts on this subject based on the ideXlab platform.

  • electromagnetic navigation bronchoscopy guided fiducial placement for robotic stereotactic radiosurgery of lung tumors a feasibility study
    Chest, 2007
    Co-Authors: Devanand Anantham, David Fellerkopman, L N Shanmugham, Stuart M Berman, Malcolm M Decamp, Sidhu P Gangadharan, Ralf Eberhardt, Felix J F Herth, Armin Ernst
    Abstract:

    Background Stereotactic radiosurgery (Cyberknife; Accuray Incorporated; Sunnyvale, CA) is a treatment option for patients who are medically unfit to undergo lung tumor resection. For precise tumor ablation, the Cyberknife requires fiducial marker placement in or near the target tumor. Fiducial placement under transthoracic CT guidance is associated with a high risk of iatrogenic pneumothorax. Electromagnetic navigation bronchoscopy (ENB) may offer a less morbid alternative to accurately deploy Fiducials to bronchoscopically invisible peripheral lung lesions. Objective Open-label, feasibility study to assess fiducial placement in peripheral lung tumors by ENB. Method Consecutive patients with peripheral lung tumors and who were evaluated to be nonsurgical candidates underwent fiducial placement under ENB. This procedure was considered successful if Fiducials were placed in or near the tumors and remained in place without migration for radiosurgery to proceed. The need for alternative or additional intrathoracic fiducial placement was documented as procedure failure. Results A total of 39 Fiducials markers were successfully deployed in eight of nine patients (89%). Of these eight successful cases, seven had Fiducials placed directly within the tumor (88%). At Cyberknife planning, 7 to 10 days after fiducial placement, 35 of 39 fiducial markers (90%) were still in place and were adequate to allow radiosurgery to proceed. No immediate bronchoscopic complications were observed. One patient had a COPD exacerbation. Another patient returned within 1 day with transient, self-limiting fever. Conclusions ENB can be used to deploy fiducial markers for Cyberknife radiosurgery of lung tumors safely and accurately without the complications associated with transthoracic placement.

Karyn A Goodman - One of the best experts on this subject based on the ideXlab platform.

  • kilovoltage imaging of implanted Fiducials to monitor intrafraction motion with abdominal compression during stereotactic body radiation therapy for gastrointestinal tumors
    International Journal of Radiation Oncology Biology Physics, 2016
    Co-Authors: E Yorke, Ying Xiong, Qian Han, Pengpeng Zhang, G Mageras, Michael Lovelock, H Pham, Jianping Xiong, Karyn A Goodman
    Abstract:

    Purpose To assess intrafraction respiratory motion using a commercial kilovoltage imaging system for abdominal tumor patients with implanted Fiducials and breathing constrained by pneumatic compression during stereotactic body radiation therapy (SBRT). Methods and Materials A pneumatic compression belt limited respiratory motion in 19 patients with radiopaque Fiducials in or near their tumor during SBRT for abdominal tumors. Kilovoltage images were acquired at 5- to 6-second intervals during treatment using a commercial system. Intrafractional fiducial displacements were measured using in-house software. The dosimetric effect of the observed displacements was calculated for 3 sessions for each patient. Results Intrafraction displacement patterns varied between patients and between individual treatment sessions. Averaged over 19 patients, 73 sessions, 7.6% of craniocaudal displacements exceeded 0.5 cm, and 1.2% exceeded 0.75 cm. The calculated single-session dose to 95% of gross tumor volume differed from planned by an average of −1.2% (range, −11.1% to 4.8%) but only for 4 patients was the total 3-session calculated dose to 95% of gross tumor volume more than 3% different from planned. Conclusions Our pneumatic compression limited intrafractional abdominal target motion, maintained target position established at setup, and was moderately effective in preserving coverage. Commercially available intrafractional imaging is useful for surveillance but can be made more effective and reliable.

  • eus guided fiducial placement for image guided radiation therapy in gi malignancies by using a 22 gauge needle with videos
    Gastrointestinal Endoscopy, 2010
    Co-Authors: Christopher J Dimaio, Satish Nagula, Karyn A Goodman, Alice Y Ho, Arnold J Markowitz, Mark A Schattner, Hans Gerdes
    Abstract:

    Background Image-guided radiation therapy (IGRT) is dependent on the presence of fiducial markers for target localization and tracking. EUS-guided placement of fiducial markers with a 19-gauge needle has been reported. However, the size and stiffness of the 19-gauge needle may compromise the safety and ease of fiducial placement. Objective The aim of this study was to evaluate the safety and feasibility of EUS-guided placement of thin flexible gold coil Fiducials by using a 22-gauge needle. Design Retrospective study. Setting Memorial Sloan-Kettering Cancer Center, between December 2008 and November 2009. Patients A total of 30 patients with GI malignancies of the mediastinum and upper abdomen who were to undergo IGRT. Interventions EUS evaluation with a curvilinear-array echoendoscope was performed. The target lesion was identified, a 22-gauge needle preloaded with a gold coil fiducial was inserted into the lesion, and the fiducial was deployed under EUS guidance. Main Outcome Measurements Technical success was defined as the ability to place Fiducials in the desired location. Immediate and delayed complications were also noted. Results A total of 69 Fiducials were placed in 12 different sites in the mediastinum and upper abdomen. Technical success was achieved in 29 out of 30 cases (97%). No intraprocedural complications were encountered. One patient developed a fever and abnormal liver function tests 12 hours after fiducial placement. Limitations Retrospective design, small case series. Conclusions EUS-guided placement of thin flexible gold coil Fiducials by using a 22-gauge needle is both safe and feasible for upper GI malignancies.