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121 results on '"Mostafavi, Hassan"'

1. Assessment of fiducial motion in CBCT projections of the abdominal tumor using template matching and sequential stereo triangulation

Author

Oderinde, Oluwaseyi M., Mostafavi, Hassan, Simpson, Daniel, Murphy, James, Kim, Gwe-Ya, and Cervino, Laura I.

Subjects
Physics - Medical Physics
Abstract

Purpose: To assess the fiducial motion in abdominal stereotactic body radiotherapy (SBRT) using the cone-beam computed tomography (CBCT) projections acquired for pre-treatment patient set-up. Materials and Methods: Pre-treatment CBCT projections and anterior-posterior (AP) and lateral (LAT) pair of fluoroscopic sequences of 7 pancreatic and 6 liver SBRT patients with implanted fiducials were analyzed for 49 treatment fractions retrospectively. A tracking algorithm based on template matching and sequential stereo triangulation algorithms was used to track the fiducials in the CBCT projections and the fluoro sequence pairs. We predicted the clinical couch adjustment from CBCT tracking and compared it with the clinical couch decision made during the patient's treatment. Results: In 3D coordinate, the fiducial motion ranges for pancreas cases were 9.90+/-3.52 mm, 10.65+/-5.91 mm, and 10.74+/-6.24 mm for CBCT, AP, and LAT fluoro, respectively, while in the liver, they were 13.93+/-3.39 mm, 11.17+/-3.75 mm, and 11.52+/-4.33 mm, respectively. Prediction of couch adjustment in LAT, SI, and AP coordinates from CBCT tracking agrees with the actual clinical couch correction within 0.92+/-0.74 mm, 1.37+/-1.26 mm, and 0.68+/-0.56 mm for pancreas cases and within 1.12+/-0.96 mm, 1.15+/-0.92 mm and 0.90+/-0.86 mm for liver cases, respectively. Conclusion: Tracking pre-treatment CBCT projections using template matching and sequential stereo triangulation is suitable for assessing fiducial motion and adjusting the patient setup for abdominal SBRT. CBCT can be used for motion modeling, potentially eliminating the need for additional fluoroscopic pair acquisition and thus reducing the imaging dose to the patient and the total treatment time.

Published
2022

8. Dynamic targeting image-guided radiotherapy

Author

Huntzinger, Calvin, Munro, Peter, Johnson, Scott, Miettinen, Mika, Zankowski, Corey, Ahlstrom, Greg, Glettig, Reto, Filliberti, Reto, Kaissl, Wolfgang, Kamber, Martin, Amstutz, Martin, Bouchet, Lionel, Klebanov, Dan, Mostafavi, Hassan, and Stark, Richard

Published
2006
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9. Characterization of Markerless Tumor Tracking Using the On-Board Imager of a Commercial Linear Accelerator Equipped With Fast-kV Switching Dual-Energy Imaging

Author

Roeske, John C., primary, Mostafavi, Hassan, additional, Haytmyradov, Maksat, additional, Wang, Adam, additional, Morf, Daniel, additional, Cortesi, Luca, additional, Surucu, Murat, additional, Patel, Rakesh, additional, Cassetta, Roberto, additional, Zhu, Liangjia, additional, Lehmann, Mathias, additional, and Harkenrider, Matthew M., additional

Published
2020
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17. Secondary Malignant Transformation of Giant Cell Tumor of Bone: Is It a Fate?

Author

Movahedinia, Sajjadeh, Shooshtarizadeh, Tina, and Mostafavi, Hassan

Subjects
GIANT cell tumors, BONE cancer, CELL transformation, BONE cells, CANCER
Abstract

The malignant transformation of conventional giant cell tumor of bone (GCTOB) is rare and usually occurs with irradiation. Here we report two neglected cases of conventional GCTOB with spontaneous malignant transformation at 11 and 16 years after initial diagnosis. In the former case, the patient refused to receive any treatment following the incisional biopsy, and in the latter, the first recurrence that occurred 5 years after initial treatment, was neglected. Although rare, the occurrence of sarcomatous changes in these cases indicates that secondary malignant transformation may be part of the natural course of this tumor. In addition, in both cases, immunohistochemistry showed diffuse and strong p53 expression in the malignant tumor but not in the primary lesion. It suggests that p53 overexpression may play a key role in the malignant transformation of GCTOB and that investigating for p53 expression in recurred lesions may help in predicting cases of giant cell tumor, prone to malignant transformation. [ABSTRACT FROM AUTHOR]

Published
2019
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26. Markerless tracking of small lung tumors for stereotactic radiotherapy.

Author

Sörnsen de Koste, John R., Dahele, Max, Mostafavi, Hassan, Sloutsky, Alex, Senan, Suresh, Slotman, Ben J., and Verbakel, Wilko F. A. R.

Subjects
TREATMENT of lung tumors, STEREOTACTIC radiotherapy, CLINICAL trials, RETROSPECTIVE studies, COMPARATIVE studies
Abstract

Purpose: (1) To validate retrospective markerless tracking software for small lung tumors by comparing tracked motion in 4-dimensional planning computed tomography (4DCT) derived kV projection images and known tumor motion in the same 4DCT. (2) To evaluate variability of tumor motion using kV projection images from cone-beam computed tomography (CBCT) scans acquired on different days. Methods: Nonclinical tumor tracking software (TTS) used a normalized cross correlation algorithm to track the tumor on enhanced kV projection images (e.g., from a CBCT scan). The reference dataset consisted of digitally reconstructed radiographs (DRRs) from one phase of a planning 4DCT. TTS matches two in-plane coordinates and obtains the out-of-plane coordinate by triangulating with match results from other projections. (1) To validate TTS, tracking results were compared with known 4DCT tumor motion for two patients (A and B). Projection images (1 image/1°) were digitally reconstructed for each 4DCT phase. From these, kV projection series were composed simulating full breathing cycles every 20° of gantry rotation [breathing period = 20°/(6°/s) = 3.33 s]. Reference templates were 360 "tumor enhanced" DRRs from the 4DCT expiration phase. TTS-derived tumor motion was compared to known tumor motion on 4DCT. (2) For five patients, TTS-assessed motion during clinical CBCT acquisition was compared with motion on the planning 4DCT, and the motion component in the Y (cranio-caudal)-direction was compared with the motion of an external marker box (RPM, real-time position management). Results: (1) Validation results: TTS for case A (tumor 6.2 cm³, 32 mm axial diameter) over 360° showed mean motion X (medial-lateral) = 3.4, Y = 11.5, and Z (ventral-dorsal) = 4.9 mm (1 SD < 1.0 mm). Corresponding 4DCT motion was X = 3.1, Y = 11.3, and Z = 5.1 mm. Correlation coefficients between TTS tumor motion and displacement of the tumor's center of mass (CoM) on 4DCT were 0.64, 0.96, and 0.82 (X, Y, and Z, respectively). For case B (4.1 cm³, 20 mm diameter), due to temporarily decreased tumor visibility preventing TTS from resolving the tumor, robust tracking data were only available between angles 300°-40° and 120°-220°. Mean motion according to TTS was X = 2.0, Y = 7.7, and Z = 8.2 mm (1 SD < 0.9 mm). Tumor motion on 4DCT was X = 1.8, Y = 7.6, and Z = 9.5 mm and correlation coefficients between TTS motion and CoM displacement were 0.59, 0.95, and 0.93 (X, Y, and Z, respectively). (2) Clinical results: TTS revealed a mean intrafraction variation in tumor motion in Y-direction of >2.0 mm (1 SD) in four of five patients. In addition, clinical tumor motion amplitude differed from that seen on planning 4DCT. Internal and external structures that create abrupt density change (e.g., table-top edge, interface between lung/mediastinum and lung/heart) were observed to prevent 360° tracking of the tumor. Correlation coefficients between TTS motion in the Y-direction and the RPM signal (22 observations) ranged from 0.78 to 0.96. In 2D, 241 TTS matches at end-inspiration and end-expiration were visually validated: mean difference was 0.8 mm (SD = 0.7) for both. Conclusions: TTS can track small lung tumors if these are visible in kV projections. A 4DCT dataset can be used to validate kV tracking of moving targets. TTS and 4DCT displacement agreed to within 2 mm. TTS and RPM motion were closely associated but tumor motion during CBCT can vary from the planning 4DCT. [ABSTRACT FROM AUTHOR]

Published
2015
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