Deukhee Lee

Robust kidney stone tracking for a non-invasive ultrasound theragnostic system-Servoing performance and safety enhancement-

We propose a non-invasive ultrasound theragnostic system that tracks movement in an affected area (kidney stones, in the present study) by irradiating the area with high-intensity focused ultrasound (HIFU). In the present paper, the concept behind a novel medical support system that integrates therapy and diagnostics (theragnostics) is illustrated. The required functions for the proposed system are discussed and an overview of the constructed system configuration is illustrated. The problems associated with kidney stone motion tracking by ultrasonography are described. In order to overcome these problems, we consider two approaches. The first approach is to minimize the servoing error so as to enhance both the efficiency of the therapy and the safety of the patient. The second approach is to reduce the effect of the servoing error. With respect to the first approach, we propose a robust detection method of the stone position based on shape information. With respect to the second approach, we propose a solution for controlling the HIFU irradiation power in accordance with the servoing error, primarily in order to enhance the safety of the patient.

Intensity-based visual servoing for non-rigid motion compensation of soft tissue structures due to physiological motion using 4D ultrasound

This paper presents a visual-servoing method for compensating motion of soft tissue structures using 4D ultra-sound. The motion of soft tissue structures caused by physiological and external motion makes it difficult to investigate them for diagnostic and therapeutic purposes. The main goal is to track non-rigidly moving soft tissue structures and compensate the motion in order to keep a lesion on its target position during a treatment. We define a 3D non-rigid motion model by extending the Thin-Plate Spline (TPS) algorithm. The motion parameters are estimated with intensity-value changes of a points set in a tracking soft tissue structure. Finally, the global rigid motion is compensated with a 6-DOF robot according to the motion parameters of the tracking structure. Simulation experiments are performed with recorded 3D US images of in-vivo soft tissue structures and validate the effectiveness of the non-rigid motion tracking method. Robotic experiments demonstrated the success of our method with a deformable phantom.

A control framework for the non-invasive ultrasound theragnostic system

The non-invasive ultrasound theragnostic system, we propose, tracks and follows movement in an affected area —kidney stones here—, while High-Intensity Focused Ultrasound (HIFU) is irradiated onto the area. In this paper, the concept of the novel medical support system, which integrates the therapy and diagnostics, is illustrated at first. Secondly, structuring the required functions for the proposed system is discussed. Third, the overview of the constructed system configuration is illustrated. Fourth, the problem of the stone motion tracking by ultrasonography is clarified. To cope with this problem, the respiratory motion of a human kidney is analyzed and a controller, by utilizing the quasi-periodical motion of the respiratory kidney motion, is proposed. Finally, the result of the servoing and HIFU irradiation experiments of the model stone, which moves based on the real human kidney motion data, is reported to confirm the effectiveness of the proposed controller and the constructed system.

Ultrasound-based visual servoing system for lithotripsy

Recently, lithotripsy (kidney stone treatment) using HIFU (high intensity focused ultrasound) was developed by researchers in therapeutic ultrasound field. The lithotripsy crushes kidney stones powder, therefore, do not harm to the surrounding tissues of the kidney stones. However, it is necessary to continuously emit high intensity ultrasound waves on a target kidney stone during treatment. Therefore, HIFU transducers should follow a target kidney stone which moves due to respiration and heartbeat. In this paper, ultrasound-based visual servoing system is described. Two ultrasound probes and a HIFU transducer are mounted on the end effector of a xyz stage machine. The two ultrasound probes visually keep track of the target kidney stone within the body, and servo the xyz stage machine. The required techniques, such as conversion of a frame of radio frequency (RF) echo signals into an ultrasound bright mode image, visual tracking, pose estimation and control, are explained.

Feed-Forward Controller for the Integrated Non-Invasive Ultrasound Diagnosis and Treatment

The integrated non-invasive ultrasound diagnosis andtreatment we propose tracks and follows movementin an affected area –kidney stones here– while High-Intensity Focused Ultrasound (HIFU) is irradiatedonto the area. High-speed CCD camera cannot beused in non-invasive diagnosis and treatment becausewe must avoid damaging healthy tissue. Servoing er-ror mainly due to ultrasound imaging and its deadtime become serious problems, unlike when a high-speed camera is used. We propose feed-forward con-trol using semi-regular kidney movement focusing onenhancing servoing performance.Keywords: non-invasive ultrasound diagnosis and treat-ment, motion tracking, feed-forward control, High Inten-sity Focused Ultrasound, medicalsupport system

A Framework of the Non-invasive Ultrasound Theragnostic System

The authors have developed an Non-Invasive Ultrasound Theragnostic System to decrease the strain of patients and medical doctors. The system we propose tracks and follows movement in an affected area ---kidney stones here--- while High-Intensity Focused Ultrasound (HIFU) is irradiated onto the area. In this paper, a framework of the non-invasive ultrasound theragnostic system is proposed and illustrated. Specifically, the concept of the system is proposed at first. Secondly, decomposing and reconstructing (structuring) of the functional requirements are discussed. Third, the constructed system, which is based on those structured functional requirements, is illustrated. Fourth, the result of the servoing experiments of the model stone is reported to confirm the effectiveness of the proposed construction methodology and constructed system.

Effect of Ag/Al co-doping method on optically p-type ZnO nanowires synthesized by hot-walled pulsed laser deposition

Silver and aluminum-co-doped zinc oxide (SAZO) nanowires (NWs) of 1, 3, and 5 at.% were grown on sapphire substrates. Low-temperature photoluminescence (PL) was studied experimentally to investigate the p-type behavior observed by the exciton bound to a neutral acceptor (A0X). The A0X was not observed in the 1 at.% SAZO NWs by low-temperature PL because 1 at.% SAZO NWs do not have a Ag-O chemical bonding as confirmed by XPS measurement. The activation energies (Ea) of the A0X were calculated to be about 18.14 and 19.77 meV for 3 and 5 at.% SAZO NWs, respectively, which are lower than the activation energy of single Ag-doped NW which is about 25 meV. These results indicate that Ag/Al co-doping method is a good candidate to make optically p-type ZnO NWs.

Image-guided handheld HIFU treatment system based on real-time tracking of ultrasound imaging probe and HIFU probe

Non-invasive surgery using high-intensity focused ultrasound (HIFU) beam allows numerous clinical applications for tumor-bearing patients. There have been researches and products implementing HIFU treatment for the past decade. However, those have disadvantages in common that their systems are of very high complexity, cost and also require too much space in the operating room. Here, we propose HIFU treatment system which can visualize predicted HIFU focal spot on the actual ultrasound image in real-time. This can be done by optically tracking HIFU probe and imaging probe respectively in real-time and localizing their positions in the same global coordinate system. Hand-eye calibration between imaging probe and ultrasound images is performed and focal point of HIFU beam can be predicted by hydrophone detection. Accuracy and safety of targeting the HIFU beam can be improved by intuitively monitoring real-time images including not only target lesions but also expected HIFU focal spot. Furthermore, by using portable handheld probes, surgeons can secure large enough space for their operations.

Markerless registration for intracerebral hemorrhage surgical system using weighted Iterative Closest Point (ICP)

It is required to use a stereotactic frame on a patients crainial surface to access an intracerebral hematoma in conventional ICH (Intracerebral Hemorrhage) removal surgery. Since ICH using a stereotactic frame is an invasive procedure and also takes a long time, we attempt to develop a robotic ICH removal procedure with a markerless registration system using an optical 3-D scanner. Preoperative planning is performed using a patients CT (Computed Tomography) images, which include the patients 3-D geometrical information on the hematoma and internal structures of brain. To register the preplanned data and the intraoperative patients data, the patients facial surface is scanned by an optical 3-D scanner on the bed in the operating room. The intraoperatively scanned facial surface is registered to the pose of the patients preoperative facial surface. The conventional ICP (Iterative Closest Point) algorithm can be used for the registration. In this paper, we propose a weighted ICP in order to improve the accuracy of the registration results. We investigated facial regions that can be used as anatomical landmarks. The facial regions for the landmarks in the preoperative 3-D model are weighted for more accurate registration. We increase weights at the relatively undeformed facial regions, and decrease weights at the other regions. As a result, more accurate and robust registration can be achieved from the preoperative data even with local facial shape changes.

Factors affecting capsular volume changes and association with outcomes after Bankart repair and capsular shift.

Background: Capsular laxity is a main contributing factor in recurrent shoulder instability and is suggested to be correlated with increased capsular volume. Arthroscopic capsular shift combined with Bankart repair can reduce the capsular volume and reinforce the redundant capsule; however, as the capsuloligamentous structure has viscoelastic properties, it is possible for the shifted and tensioned capsule of the glenohumeral joint to slowly stretch out again over time, resulting in an increase in capsular volume. Purpose: To analyze changes in capsular volume of the glenohumeral joint over time after arthroscopic Bankart repair and capsular shift, the factors associated with these changes, and their relevance to outcomes. Study Design: Case series; Level of evidence, 4. Methods: Included in this study were 105 patients (mean age, 25.8 ± 8.2 years) who underwent arthroscopic Bankart repair and capsular shift for anterior shoulder instability and computed tomography arthrography (CTA) at 3 months and 1 year postoperatively and whose various functional outcomes were evaluated preoperatively and at the last follow-up (>12 months). Among these patients, 27 also had preoperative CTA. These 27 patients were used to make comparisons between preoperative and 3-month postoperative CTA measurements, and all 105 patients were used for all other comparisons. Two raters measured the separate anterior and posterior capsular volume and cross-sectional area at the 5-o’clock position using 3-dimensional (3D) Slicer software. These measurements were subsequently adjusted for each glenoid size. The changes in capsular volume and cross-sectional area at the 5-o’clock position over time, the factors related to higher change in anterior capsular volume, and their correlation with outcomes were evaluated. Results: Three months postoperatively, the total and anterior capsular volume and anterior cross-sectional area significantly decreased; however, these values increased again at 1 year postoperatively (all P < .01). The inter- and intraobserver reliabilities of the measurements were excellent (interclass correlation coefficient = 0.717-0.945). Female sex, being an elite athlete, and more dislocations before surgery were related to a higher increase in anterior capsular volume at 1 year (all P < .05). Eight patients had redislocation, and 18 exhibited positive apprehension test postoperatively, and these patients showed significantly higher increases in anterior and total capsular volume at 1 year than did those without redislocation or positive apprehension sign (all P < .01). However, with the exception of Rowe score, a higher increase in anterior capsular volume was not related to functional outcome measures. Conclusion: Surgeons should be aware of the re-increase in anterior capsular volume or restretching trait of the anterior capsule over time, even after successful arthroscopic Bankart repair and capsular shift. In this study, women, elite athletes, and those with frequent dislocations were at high risk of capsular restretching. An increase in capsular volume was related to redislocation and positive apprehension sign as well as with Rowe score.