scholarly journals Reproducibility of a Noninvasive System for Eye Positioning and Monitoring in Stereotactic Radiotherapy of Ocular Melanoma

2017 ◽  
Vol 16 (3) ◽  
pp. 352-356 ◽  
Author(s):  
Omar Iskanderani ◽  
Dominique Béliveau-Nadeau ◽  
Robert Doucet ◽  
Geneviève Coulombe ◽  
Deborah Pascale ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Optic Nerve ◽  
Stereotactic Radiotherapy ◽  
Choroidal Melanoma ◽  
Target Volume ◽  
Visual Monitoring ◽  
3 Dimensional ◽  
Computed Tomography Scans ◽  
Visual Monitoring System ◽  
Anterior Posterior

Purpose: Our preferred treatment for juxtapapillary choroidal melanoma is stereotactic radiotherapy. We aim to describe our immobilization system and quantify its reproducibility. Materials and Methods: Patients were identified in our radiosurgery database. Patients were imaged at computed tomography simulator with an in-house system which allows visual monitoring of the eye as the patient fixates a small target. All patients were reimaged at least once prior to and/or during radiotherapy. The patients were treated on the CyberKnife system, 60 Gy in 10 daily fractions, using skull tracking in conjunction with our visual monitoring system. In order to quantify the reproducibility of the eye immobilization system, computed tomography scans were coregistered using rigid 6-dimensional skull registration. Using the coregistered scans, x, y, and z displacements of the lens/optic nerve insertion were measured. From these displacements, 3-dimensional vectors were calculated. Results: Thirty-four patients were treated from October 2010 to September 2015. Thirty-nine coregistrations were performed using 73 scans (2-3 scans per patient). The mean displacements of lens and optic nerve insertion were 0.1 and 0.0 mm. The median 3-dimensional displacements (absolute value) of lens and nerve insertion were 0.8 and 0.7 mm (standard deviation: 0.5 and 0.6 mm). Ninety-eight percent of 3-dimensional displacements were below 2 mm (maximum 2.4 mm). The calculated planning target volume (PTV) margins were 0.8, 1.4, and 1.5 mm in the anterior–posterior, craniocaudal, and right–left axes, respectively. Following this analysis, no further changes have been applied to our planning margin of 2 to 2.5 mm as it is also meant to account for uncertainties in magnetic resonance imaging to computed tomography registration, skull tracking, and also contouring variability. Conclusion: We have found our stereotactic eye immobilization system to be highly reproducible (<1 mm) and free of systematic error.

scholarly journals Does Interfraction Cone Beam Computed Tomography Improve Target Localization in Prostate Bed Radiotherapy?

2019 ◽  
Vol 18 ◽  
pp. 153303381983196 ◽  
Author(s):  
Sara Elakshar ◽  
James Man Git Tsui ◽  
Michael Jonathan Kucharczyk ◽  
Nada Tomic ◽  
Ziad Simon Fawaz ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Radical Prostatectomy ◽  
Cone Beam Computed Tomography ◽  
Target Volume ◽  
Interquartile Range ◽  
Cone Beam ◽  
Prostate Bed ◽  
Computed Tomography Images ◽  
Computed Tomography Scans ◽  
Anterior Posterior

Purpose: In this prospective phase II study, we investigated whether cone beam computed tomography scan was a superior method of image-guided radiotherapy relative to 2D orthogonal kilovoltage images in the post-radical prostatectomy setting. Methods: A total of 419 treatment fractions were included in this analysis. The shifts required to align the patient for each treatment were performed using 3D matching between cone beam computed tomography scans and the corresponding computed tomography images used for planning. This was compared with the shifts obtained from 2D orthogonal kilovoltage images, matching with the corresponding digitally reconstructed radiographs. Patients did not have fiducials inserted to assist with localization. Interfractional changes in the bladder and rectal volumes were subsequently measured on the cone beam computed tomography images for each fraction and compared to the shift differences between orthogonal kilovoltage and cone beam computed tomography scans. The proportion of treatment fractions with a shift difference exceeding the planning target volume of 7 mm, between orthogonal kilovoltage and cone beam computed tomography scans, was calculated. Results: The mean vertical, lateral, and longitudinal shifts resulted from 2D match between orthogonal kilovoltage images and corresponding digitally reconstructed radiographs were 0.353 cm (interquartile range: 0.1-0.5), 0.346 cm (interquartile range: 0.1-0.5), and 0.289 cm (interquartile range: 0.1-0.4), compared to 0.388 cm (interquartile range: 0.1-0.5), 0.342 cm (interquartile range: 0.1-0.5), and 0.291 cm (interquartile range: 0.1-0.4) obtained from 3D match between cone beam computed tomography and planning computed tomography scan, respectively. Our results show a significant difference between the kilovoltage and cone beam computed tomography shifts in the anterior–posterior direction ( P = .01). The proportion of treatment fractions in which the differences in kilovoltage and cone beam computed tomography shifts between exceeded the 7 mm planning target volume margin was 6%, 2%, and 3% in the anterior–posterior, lateral, and superior–inferior directions, respectively. Conclusion: We prospectively demonstrated that the daily use of volumetric cone beam computed tomography for treatment localization in post-radical prostatectomy patients demonstrated an increased need for a shift in patient position. This suggests that in post-radical prostatectomy patients the daily cone beam computed tomography imaging improved localization of the prostate bed and may have prevented a limited number of geographic misses, compared to daily kilovoltage imaging that was not assisted with fiducials.

Accurate registration of cone-beam computed tomography scans to 3-dimensional facial photographs

2014 ◽  
Vol 145 (2) ◽  
pp. 256-264 ◽  
Author(s):  
Kyung-Yen Nahm ◽  
Yong Kim ◽  
Yong-Suk Choi ◽  
Jeongjin Lee ◽  
Seong-Hun Kim ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Cone Beam Computed Tomography ◽  
Cone Beam ◽  
3 Dimensional ◽  
Computed Tomography Scans

Osteoplastic Pterional Craniotomy Revisited

2011 ◽  
Vol 68 (suppl_1) ◽  
pp. ons125-ons129 ◽  
Author(s):  
Ealmaan Kim ◽  
Johnny B. Delashaw
Keyword(s):  
Computed Tomography ◽  
Muscle Function ◽  
Bone Flap ◽  
Temporalis Muscle ◽  
Pterional Approach ◽  
3 Dimensional ◽  
Pterional Craniotomy ◽  
Computed Tomography Scans ◽  
Brain Aneurysms ◽  
Additional Labor

Abstract BACKGROUND: A standard pterional approach with a free bone flap to treat brain aneurysms was first introduced and popularized by Yaşargil. OBJECTIVE: To describe a modified pterional craniotomy technique and that mobilizes part of the sphenoid wing and the pterion in a block with the temporalis muscle to enhance cosmetic results. METHODS: A subperiosteal corridor is provided inferiorly by separating the temporalis muscle from the underlying bone in a retrograde dissection. Inferior chisel cuts from the front and back enter the sphenoid wing, enabling removal of part of the sphenoid wing and the pterion in 1 piece, along with the bone flap. Forty patients with aneurysms were treated in this fashion, and the cosmetic outcome was examined at 6 months postoperatively. RESULTS: Thirty-seven patients (92.5%) demonstrated an unremarkable degree of temporalis muscle atrophy. Excellent configuration and fusion of the pterional bone flap were observed on 3-dimensional computed tomography scans. CONCLUSION: With the use of this muscle-preserving and bone-sparing pterional approach and with little additional labor, temporalis muscle function is preserved and improved cosmesis is obtained.

scholarly journals PO 18235 - New tomographic method for measuring metatarsal rotation in hallux valgus

2019 ◽  
Vol 13 (Supl 1) ◽  
pp. 52S
Author(s):  
Bruno Rodrigues de Miranda ◽  
Rui Dos Santos Barroco ◽  
Leticia Zaccaria Prates de Oliveira ◽  
Mahmoud Beerens Abdul Ghani Abdul Ghani ◽  
Antonio Candido de Paula Neto ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Hallux Valgus ◽  
Weight Bearing ◽  
Alpha Angle ◽  
Metatarsal Bone ◽  
3 Dimensional ◽  
First Metatarsal ◽  
Computed Tomography Scans ◽  
Tomographic Method ◽  
The Relationship

Introduction: Hallux valgus is a 3-dimensional deformity involving an increased intermetatarsal I/II angle and a rotational deformity of the first metatarsal bone. Kim et al. developed a method for measuring the tibial sesamoid position relative to the coronal rotation of the first metatarsal bone in computed tomography scans under simulated weight-bearing conditions. Objective: To describe a method for the topographic assessment of the correction of tibial sesamoid and metatarsal pronation using computed tomography scans under simulated weight-bearing and active toe extension. Method: We performed computed tomography under simulated weight-bearing conditions with and without active toe dorsiflexion, observing the degree of metatarsal pronation and sesamoid subluxation. For measurement purposes, we used the classifications of Kim et al. and Smith et al. Results: We observed tomographic correction, both angular and rotational, by measuring the intermetatarsal angle and tibial sesamoid position, which were confirmed by the change in the alpha angle suggested by Kim et al. Discussion: Toe extension was described as a peroneus longus tendon activation test by Klemola et al., who used this maneuver to demonstrate clinical rotational correction of hallux valgus. We described the use of a tomographic technique that followed this principle to preoperatively observe the underlying factors that may affect the rotational correction of the deformity. Conclusion: The method has the capacity for correction in various planes involving derotation of the first metatarsal bone and the relationship between such derotation and the change in sesamoid position in relation to the coronal plane of the foot.

Accuracy and Reliability of a Simple Calculation for Measuring Glenoid Bone Loss on 3-Dimensional Computed Tomography Scans

2018 ◽  
Vol 34 (1) ◽  
pp. 84-92 ◽  
Author(s):  
Stephen A. Parada ◽  
Josef K. Eichinger ◽  
Guillaume D. Dumont ◽  
Carrie A. Parada ◽  
Alyssa R. Greenhouse ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Bone Loss ◽  
Simple Calculation ◽  
Glenoid Bone Loss ◽  
3 Dimensional ◽  
Computed Tomography Scans

scholarly journals Frontal Angle: A New Predictor of Difficulty in Endoscopic Frontal Sinus Surgery—A Preliminary Computed Tomography Study

2021 ◽  
pp. 014556132110038
Author(s):  
Paulina Kołodziejczyk ◽  
Tomasz Gotlib ◽  
Kazimierz Niemczyk
Keyword(s):  
Computed Tomography ◽  
Frontal Sinus ◽  
Posterior Wall ◽  
Sinus Surgery ◽  
Posterior Aspect ◽  
3 Dimensional ◽  
Frontal Sinus Surgery ◽  
Plane Tangent ◽  
Nasal Floor ◽  
Anterior Posterior

Objectives: The possibility of visualization of the frontal sinus during endoscopic surgery depends on 3-dimensional configuration of the frontal sinus opening (FSO). We aimed to determine the prevalence of unfavorable angulation of the lower part of the posterior wall of the frontal sinus and its relation to FSO diameter. Methods: One hundred and twenty-eight computed tomography (CT) scans were retrospectively reviewed to measure (1) the angle between the nasal floor and the plane tangent to the posterior table of the frontal sinus above the most posterior aspect of the anterior buttress (frontal angle, FA) and (2) dimensions of the FSO. Results: The FA ranged from below 30° to 90°. Nearly 13% of sinuses (16.4% of patients) showed FA about 90°, which should enable good visualization of the sinus with the 30° scope after opening and clearing the frontal recess, while 4% (6.25% of patients) showed FA ≤ 30°. The anterior–posterior diameter (A-PD) was below 5 mm in 17.6% of sinuses (26.6% of patients). There was a significant correlation between FA and A-PD. Unfavorable combination of FA and A-PD (<45°, <5 mm) was present in 5.2% of sinuses (8.6% of patients), and extremely unfavorable combination (<30°, <5 mm) in 0.8% (0.8% of patients). Conclusions: The FA shows great interindividual variability, which is very likely to reflect the possibility of inspection of the frontal sinus. This implies a need for further prospective clinical studies to validate FA as a predictor of difficulty in frontal sinus surgery.

scholarly journals Use of 4-Dimensional Cone Beam Computed Tomography Scan to Estimate the Planning Target Volume Margin in Lung Tumors

2020 ◽  
Vol 06 (03) ◽  
pp. 127-133
Author(s):  
B. Namratha Sai Reddy ◽  
Rashmi Shivananjappa ◽  
Geeta S.N ◽  
Richa Tiwari
Keyword(s):  
Computed Tomography ◽  
Ct Scan ◽  
Planning Target Volume ◽  
Lower Lobe ◽  
Target Volume ◽  
Lung Tumors ◽  
Middle Lobe ◽  
Tumor Motion ◽  
Internal Target Volume ◽  
Anterior Posterior

Abstract Introduction This study aimed to estimate the planning target volume (PTV) margin in lung tumors using 4D computed tomography (CT) scan and evaluate other factors that have an effect on tumor motion. Materials and Methods We recruited 43 biopsy-proven, newly diagnosed carcinoma lung patients who were treated with definitive intent from January 2017 to June 2018. The radiation dose was delivered using a 3D conformal radiation therapy (CRT)/intensity-modulated radiotherapy (IMRT)/volumetric modulated arc therapy (VMAT) plan to a dose of 6000 to 6600 cGy in 30 or more fractions to the whole primary. All patients underwent 4D CT scan on the Elekta machine where all the 10 phases of respiration in free breathing were recorded. These phases are fused with CT simulation images, on which gross tumor volume (GTV) and clinical target volume (CTV) are contoured in all phases of respiration. Following this, an internal target volume (ITV) was created by measuring tumor motion all the directions from the center of tumor and PTV was concluded. Results The mean ITV for tumor in all six directions, that is, in superior, inferior, anterior, posterior, medial and lateral directions was 0.9, 0.9, 0.8, 0.9, 0.8, and 0.9 cm, respectively. For coverage of tumor for 90% of patients, the margins required in superior, inferior, anterior, posterior, medial, and lateral directions were 1.3, 1.5, 1.5, 1.4, 1.5, and 1.3 cm, respectively. Other factors such as size of the tumor and location of the tumor did not significantly contribute to PTV changes in our study. Conclusion Mean ITV for tumor in all six directions summed up to be 0.8 cm, but there was significant movement in inferior direction for upper lobe tumors (0.9 cm) (p = 0.008), in medial direction for middle lobe tumors (0.8 cm) (p = 0.05), and in medial direction for lower lobe tumors (0.75 cm) (p = 0.005).

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