• Progress in Medical Physics
• /
• v.14 no.3
• /
• pp.167-174
• /
• 2003

In the radiation treatment planning (RTP) process, especially for stereotactic radiosurgery (SRS), knowing the exact volume and shape and the precise position of a lesion is very important. Sometimes X-ray projection images, such as angiograms, become the best choice for lesion identification. However, while the exact target position can be acquired by bi-projection images, 3D target reconstruction from bi-projection images is considered to be impossible. The aim of this study was to reconstruct the 3D target volume from multiple projection images. It was assumed that we knew the exact target position in advance, and all processes were performed in Target Coordinates, where the origin was the center of the target. We used six projections: two projections were used to make a Reconstruction Box and four projections were for image acquisition. The Reconstruction Box was made up of voxels of 3D matrices. Projection images were transformed into 3D in this virtual box using a geometric back-projection method. The resolution and the accuracy of the reconstructed target volume were dependent on the target size. An algorithm was applied to an ellipsoid model and a horseshoe-shaped model. Projection images were created geometrically using C program language, and reconstruction was also performed using C program language and Matlab ver. 6(The Mathwork Inc., USA). For the ellipsoid model, the reconstructed volume was slightly overestimated, but the target shape and position proved to be correct. For the horseshoe-shaped model, reconstructed volume was somewhat different from the original target model, but there was a considerable improvement in determining the target volume.

• Journal of the Korean Society of Radiology
• /
• v.79 no.6
• /
• pp.315-322
• /
• 2018

Purpose: To analyze the clinical and angiographic features with outcome of transcatheter arterial embolization in patients with secondary postpartum hemorrhage. Materials and Methods: Clinical details and angiographic features with assessment of arterial embolization were reviewed in total 38 patients underwent arterial embolization at single tertiary referral center. Results: Twenty patients (53%) had Cesarean section. The major causes of bleeding were iatrogenic vascular injury, and retained placenta (55%). The patterns of vaginal bleeding were recorded as intermittent (50%), or as persistent (50%). Seven patients (18%) were hemodynamically unstable at presentation. Positive angiographic findings appeared in eighteen patients (47.3%). The frequency of pseudoaneurysm was statistically high in the Cesarean section (p < 0.001). The used embolic agents except gelfoam were N-butyl cyanoacrylate (n = 7), and microcoil (n = 7). Unilateral selective embolization (26.3%) was shown effective in superselective embolization of bleeding focus. Technical and clinical success rate were 100% and 97.4%, respectively with no complication. Sixteen resumed regular menstruation, and one pregnancy were observed in patients with available follow-up of over 6 months. Conclusion: Considerable rate of hemodynamically unstable patients was observed with high rate of positive angiography findings. Given high successful rate and few complications, early angiographic assessment with embolization should be considered.

• Journal of Chest Surgery
• /
• v.38 no.8 s.253
• /
• pp.529-537
• /
• 2005

Background: Historically the Fontan operation in patients with single ventricle and heterotaxy syndrome has been associated with high mortality because of systemic or pulmonary anomalous venous drainage, incompetent common atrioventricular valve, right ventricle type univentricular heart, and arrhythmia. Material and Method: A retrospective review of 62 patients $(age:\;54.79\pm33.97\;months)$ with heterotaxy syndrome who underwent a extracadiac Fontan operation between 1996 and 2005 was performed. Twenty one patients had left atrial isomerism, and 41 had right isomerism. The Fontan procedure was staged in all but 2 patients, and a fenestration was less placed in left isomerism. Result: Left isomerism was associated more with interrupted inferior vena cava and pulmonary arteriovenous fistula, and right isomerism was associated more with anomalous pulmonary venous drainage, common atrioventricular valve and morphologic right ventricle. There were 3 hospital deaths$(4.8\%)$ and 3 late deaths $(5.2\%)$ with a follow-up duration of $48.8\pm31.0$ months. Eight-year survivals were $90.5\pm6.4\%$ in left isomerism and $88.6\pm5.4\%$ in right isomerism (p=0.94). At 8 years, freedom from reoperation was $73.9\pm11.3\%$ in left isomerism, and $82.3\pm6.7\%$ in right isomerism (p=0.87). Atrioventricular valve regurgitation progressed after Fontan operation in heterotaxy syndrome, and reoperation for pulmonary arteriovenous fistula and permanent pacemaker implantation for sinus node dysfunction were required more in left isomerism. Conclusion: The extracardiac Fontan operation can now be performed in patients with heterotaxy syndrome with excellent survival. However, morbidity in terms of postoperative atrioventricular valve regurgitation, arrhythmia, and pulmonary arteriovenous fistula remains significant.

• Progress in Medical Physics
• /
• v.23 no.3
• /
• pp.177-187
• /
• 2012

Magnetic resonance angiography (MRA) techniques are widely used in diagnosis of vascular disorders such as hemadostenosis and aneurism. Especially, phase contrast (PC) MRA technique, which is a typical non contrast-enhanced MRA technique, provides not only the anatomy of blood vessels but also flow velocity. In this study, we developed the 2- and 3-dimensional PC MRA pulse sequences for a low magnetic field MRI system. Vessel images were acquired using 2D and 3D PC MRA and the velocities of the blood flow were measured in the superior sagittal sinus, straight sinus and the confluence of the two. The 2D PC MRA provided the good quality of vascular images for large vessels but the poor quality for small ones. Although 3D PC MRA gave more improved visualization of small vessels than 2D PC MRA, the image quality was not enough to be used for diagnosis of the small vessels due to the low SNR and field homogeneity of the low field MRI system. The measured blood velocities were $25.46{\pm}0.73cm/sec$, $24.02{\pm}0.34cm/sec$ and $26.15{\pm}1.50cm/sec$ in the superior sagittal sinus, straight sinus and the confluence of the two, respectively, which showed good agreement with the previous experimental values. Thus, the developed PC MRA technique for low field MRI system is expected to provide the useful velocity information to diagnose the large brain vessels.

• Radiation Oncology Journal
• /
• v.18 no.4
• /
• pp.251-256
• /
• 2000

Purpose : To evaluate efficacy and complication of stereotactic radiosurgery using stereotactic body frame. Methods and Materials :From December 1997 to June 1999, 11 patients with primary and metastatic tumors were treated with stereotactic radiosurgery using stereotactic body frame(Precision TherapyTu). Three patients were treated with primary hepatoma and seven with metastatic tumor from liver, lung, breast, trachea and one with arteriovenous malformation on neck. We used vacuum pillow for immobilization and made skin marker on sternum and tibia area with chest marker and leg marker. Diaphragm control was used for reducing movement by respiration. CT-simulation and treatment planning were peformed. Set-up error was checked by CT-Simulator before each treatment. Dose were calculated on the 80$\~$90$\%$ isodose of isocenter dose and given consecutive 3 fractions for total dose of 30 Gy (10 Gy/fraction). Results :Median follow-up was 12 months. One patient (9$\%$) showed complete response and four Patients (36$\%$) showed partial response and others showed stable disease. Planning target volumes (PTV) ranged from 3 to 111 cc (mean 18.4 n). Set-up error was within 5 mm in all directions (X, Y, Z axis). There was no complication in all patients. Conclusion :In Primary and metastatic tumors, stereotactic body frame is very safe, accurate and effective treatment modality.