• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.439-441
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• 2002

The aim of this study is to reconstruct the 3D target volume from multiple projection images. It was assumed that we were already aware of the target position exactly, and all processes were performed in Target Coordinates whose 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. Reconstruction Box was made up of voxels of 3D matrix. Projection images were transformed into 3D volume in this virtual box using geometrical based back-projection method. Algorithm was applied to an ellipsoid model and horse-shoe shaped model. Projection images were created using C program language by geometrical method and reconstruction was also accomplished using C program language and Matlab(The Mathwork Inc., USA). For ellipsoid model, reconstructed volume was slightly overestimated but target shape and position was proved to be correct. For horse-shoe shaped model, reconstructed volume was somewhat different from original target model but there was a considerable improvement in target volume determination.

• Archives of Plastic Surgery
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• v.41 no.5
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• pp.550-555
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• 2014

Background Nipple reconstruction following breast mound reconstruction is the final step in breast reconstruction. Although nipple reconstruction is a simple surgery, the psychological aspects of nipple reconstruction are thought to be important. Nipple projection is a key factor in determining patient satisfaction with the surgery. In the present study, the Hammond flap technique was introduced for nipple reconstruction. Methods Twenty-six patients who had undergone breast reconstruction from February 2008 to March 2012 were enrolled in this prospective study. All patients were evaluated based on preoperative photos, and their nipple diameters and heights were measured. Postoperative evaluation was conducted 3, 6, 9, and 12 months following nipple reconstruction. A questionnaire on patient satisfaction with the nipple reconstruction was administered 12 months after nipple reconstruction. Moreover, the same plastic surgeon scored nipple projection and overall cosmetic result of the new nipple. Results The mean projection was 4.4 mm (range, 3-6 mm), and it well matched the contralateral nipple. Twelve months following nipple reconstruction, the mean reduction rate in the nipple projection was 43.6%. Patients were satisfied or very satisfied with the nipple projection and the overall cosmetic result in 80.7% cases. Conclusions In the present study, compared with other techniques, the use of the Hammond flap technique in nipple reconstruction showed competitive results with regard to nipple projection and patient satisfaction.

• Archives of Plastic Surgery
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• v.48 no.6
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• pp.590-598
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• 2021

Background Although the initial projection after primary nipple reconstruction is excellent, nipple projection gradually flattens in most cases due to multiple causes. Although various methods have been reported to rebuild the nipple after nipple flattening, the most effective method of secondary nipple reconstruction remains unknown. The aim of this study was to review our institution's experiences with secondary nipple reconstruction. Methods We conducted a retrospective review from March 2012 to January 2019. We performed secondary nipple reconstruction if the primary reconstructed nipple height differed by more than 6 mm from the normal nipple height. We chose the method of nipple revision according to the degree of tissue scarring and the remaining nipple projection. Results We performed secondary nipple reconstruction on a total of 27 nipples, using purse-string sutures for 19 nipples and star flaps in eight nipples. The median follow-up period was 8 months (range, 6-19 months) after the final nipple reconstruction. Among the 19 nipples reconstructed using purse-string sutures, 10 (53%) demonstrated acceptable projection of more than 5 mm. Among the eight nipples reconstructed using star flaps, six (75%) showed acceptable projection of more than 5 mm. Most of the patients (73%) were satisfied (scores of 4 or 5) with the nipple reconstruction overall. Conclusions Few studies have presented favorable outcomes of secondary nipple reconstruction. When the star flap and purse-string suture methods were used depending on the remaining nipple height and scarring, appropriate projection could be achieved.

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

• Archives of Plastic Surgery
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• v.42 no.3
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• pp.309-315
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• 2015

Background Breast projection is a critical element of breast reconstruction aesthetics, but little has been published regarding breast projection as the firm expander is changed to a softer implant. Quantitative data representing this loss in projection may enhance patient education and improve our management of patient expectations. Methods Female patients who were undergoing immediate tissue-expander breast reconstruction with the senior author were enrolled in this prospective study. Three-dimensional camera software was used for all patient photographs and data analysis. Projection was calculated as the distance between the chest wall and the point of maximal projection of the breast form. Values were calculated for final tissue expander expansion and at varying intervals 3, 6, and 12 months after implant placement. Results Fourteen breasts from 12 patients were included in the final analysis. Twelve of the 14 breasts had a loss of projection at three months following the implant placement or beyond. The percentage of projection lost in these 12 breasts ranged from 6.30% to 43.4%, with an average loss of projection of 21.05%. Conclusions This study is the first prospective quantitative analysis of temporal changes in breast projection after expander-implant reconstruction. By prospectively capturing projection data with three-dimensional photographic software, we reveal a loss of projection in this population by three months post-implant exchange. These findings will not only aid in managing patient expectations, but our methodology provides a foundation for future objective studies of the breast form.

• Proceedings of the KIEE Conference
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• 1979.08a
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• pp.158-159
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• 1979

Based on minimum-mean-sqare error criterion, a noise filtering algorithm for the reconstruction of an image function from noisy projection data is suggested. The filter is constructed with a few projection data. This algorithm requires less computational time compared with other noise filtering algorithm.

• Journal of the Korean Institute of Telematics and Electronics
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• v.17 no.1
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• pp.23-30
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• 1980

The reconstruction problem in a low dose case requires some compromise of resolution and noise artifacts, and also some modification of filter kernels depending on the signal-to-noise ratio of projection data. In this paper, ail algorithm for the reconstruction of an image function from noisy projection data is suggested, based on minimum-mean-square error criterion. Modification of the falter kernel is made from information (statistics) obtained from the projection data. The simulation study Proves that this algorithm, based on the Wiener falter approach, provides substantially improved image with reduction of noise as well as improvement of the resolution. An approximate method was also studied which leads to the possible use of a recursive filter in the convolution process of image reconstruction.

• Archives of Plastic Surgery
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• v.41 no.2
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• pp.158-162
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• 2014

Background Loss of nipple projection is a common problem following nipple reconstruction. The aim of this study was to demonstrate that the use of a tightly rolled dermal graft is effective in the long-term maintenance of nipple projection. Methods Nipple reconstruction was performed using the C-V flap technique. A dermal graft was harvested from the dog-ear portion of previous scars. The graft was rolled tightly into a compact cylinder and used to augment the nipple reconstruction. Postoperatively, stacked Allevyn dressing was used for protecting the nipple from compression for a minimum of two months. Nipple projection was measured at the time of surgery and at 12 months postoperatively. Results Forty nipple reconstructions were performed using this technique. There were 19 transverse rectus abdominis musculocutaneous (TRAM) flaps, 10 latissimus dorsi (LD) flaps, and 11 tissue-expanded breast mounds. At one year, the mean projection was 0.80 cm (range, 0.62-1.22 cm). The twelve-month average maintenance of nipple projection was 70.2% for the TRAM flap group, 76.3% for the LD flap group, and 61.8% for the tissue-expanded group. In two patients with previous irradiation of the reconstructed breasts, relatively poor maintenance of nipple projection was noted (45.7%). No complications were noted, and all of the donor sites healed well primarily. Conclusions Our results demonstrated that the use of a C-V flap with a tightly rolled dermal graft for nipple reconstruction improves the long-term maintenance of nipple projection. Its advantages include reproducibility, technical simplicity, cost-effectiveness, and minimal donor site morbidity.

• Journal of Biomedical Engineering Research
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• v.15 no.3
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• pp.275-280
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• 1994

In the case of the image reconstruction from unknown projection data such as imaging the object with opaque obstructions, conventional reconstruction algorithms may reconstruct a degraded image. In this paper, a new method for the estimation of the unknown projection data based on known projection data and the bandwidth of projection data is proposed. The proposed method successfully estimates the unknown projection data through iterative transformation between projection space and frequency space using the known projection data and the bandwidth of the projection data. Computer simulation shows that the proposed method significantly improves image quality and convergence behavior over conventional algorithms. In addition, the proposed method is successfully applied to ultrasound attenuation CT using a sponge phantom.

• ETRI Journal
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• v.37 no.6
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• pp.1251-1258
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• 2015

We investigate an image recovery method for sparse-view computed tomography (CT) using an iterative shrinkage algorithm based on a second-order approach. The two-step iterative shrinkage-thresholding (TwIST) algorithm including a total variation regularization technique is elucidated to be more robust than other first-order methods; it enables a perfect restoration of an original image even if given only a few projection views of a parallel-beam geometry. We find that the incoherency of a projection system matrix in CT geometry sufficiently satisfies the exact reconstruction principle even when the matrix itself has a large condition number. Image reconstruction from fan-beam CT can be well carried out, but the retrieval performance is very low when compared to a parallel-beam geometry. This is considered to be due to the matrix complexity of the projection geometry. We also evaluate the image retrieval performance of the TwIST algorithm -sing measured projection data.