• Journal of the Korea Computer Graphics Society
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• v.28 no.2
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• pp.11-19
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• 2022

Recently, various researches on medical image generation have been suggested, and it becomes crucial to accurately evaluate the quality and diversity of the generated medical images. For this purpose, the expert's visual turing test, feature distribution visualization, and quantitative evaluation through IS and FID are evaluated. However, there are few methods for quantitatively evaluating medical images in terms of fidelity and diversity. In this paper, images are generated by learning a chest CT dataset of non-small cell lung cancer patients through DCGAN and PGGAN generative models, and the performance of the two generative models are evaluated in terms of fidelity and diversity. The performance is quantitatively evaluated through IS and FID, which are one-dimensional score-based evaluation methods, and Precision and Recall, Improved Precision and Recall, which are two-dimensional score-based evaluation methods, and the characteristics and limitations of each evaluation method are also analyzed in medical imaging.

• Archives of Craniofacial Surgery
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• v.24 no.6
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• pp.266-272
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• 2023

Background: In recent years, there has been an increase in reports of perioral vascular complications resulting from filler injections, such as necrosis of the lip or alar rim, occlusion, and in severe cases, blindness. Conversely, the use of perioral arterial flaps is becoming more prevalent in the treatment of cleft lips, cancer, and trauma. A thorough understanding of perioral arteries is essential to minimize complications and maximize the success of these flaps. However, the course of the facial artery (FA) in the perioral region remains incompletely understood. The aim of this study was to describe the variations of the FA in the perioral region. Methods: We dissected 52 embalmed and formaldehyde-fixed Vietnamese cadavers. We then studied the size and distribution of perioral arteries in 102 specimens. Results: The superior labial artery (SLA) was the most common branch, occurring in 87.25% of cadavers, followed by the inferior labial artery (ILA) at 78.43%. The SLA primarily originated above the mouth corner (cheilion), accounting for 91.01% of cases, and predominantly exhibited a tortuous course within the submucosa (78.65%). The ILA's branching pattern varied, but it was primarily located below the cheilion (91.25%). The ILA also followed a twisted path, generally within the submucosa. The ILA exhibited two patterns: the typical pattern, distributed at the vermilion border of the lower lip (8.82%), and the horizontal labiomental artery pattern, which ran horizontally in the middle of the lower lip area (69.61%). At their origin, the SLA and ILA had average external diameters of 1.29 mm and 1.28 mm, respectively. Conclusion: Numerous anatomical variations in the FA in the perioral region were found. A detailed anatomic description, suggested landmarks, and angiography before the procedure will be useful to help doctors avoid complications.

• Korean Journal of Radiology
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• v.21 no.8
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• pp.946-954
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• 2020

Objective: To investigate preoperative magnetic resonance imaging (MRI) findings associated with resection margin status in patients with invasive lobular carcinoma (ILC) who underwent breast-conserving surgery. Materials and Methods: One hundred and one patients with ILC who underwent preoperative MRI were included. MRI (tumor size, multifocality, type of enhancing lesion, distribution of non-mass enhancement [NME], and degree of background parenchymal enhancement) and clinicopathological features (age, pathologic tumor size, presence of ductal carcinoma in situ [DCIS] or lobular carcinoma in situ, presence of lymph node metastases, and estrogen receptor/progesterone receptor/human epidermal growth factor receptor type 2 status) were analyzed. A positive resection margin was defined as the presence of invasive cancer or DCIS at the inked surface. Logistic regression analysis was performed to determine pre- and postoperative variables associated with positive resection margins. Results: Among the 101 patients, 21 (20.8%) showed positive resection margins. In the univariable analysis, NME, multifocality, axillary lymph node metastasis, and pathologic tumor size were associated with positive resection margins. With respect to preoperative MRI findings, multifocality (odds ratio [OR] = 3.977, p = 0.009) and NME (OR = 2.741, p = 0.063) were associated with positive resection margins in the multivariable analysis, although NME showed borderline significance. Conclusion: In patients with ILC, multifocality and the presence of NME on preoperative breast MRI were associated with positive resection margins.

• Progress in Medical Physics
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• v.34 no.4
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• pp.48-54
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• 2023

Purpose: In this study, the dosimetric characteristics of lung stereotactic body radiotherapy (SBRT) plans using the new Halcyon system were analyzed to assess its suitability. Methods: We compared the key dosimetric parameters calculated for the Halcyon SBRT plans with those of a conventional C-arm linear accelerator (LINAC) equipped with a high-definition multileaf collimator (HD-MLC)-Trilogy Tx. A total of 10 patients with non-small-cell lung cancer were selected, and all SBRT plans were generated using the RapidArc technique. Results: Trilogy Tx exhibited significant superiority over Halcyon in terms of target dose coverage (conformity index, homogeneity index, D_{0.1 cc}, and D_95%) and dose spillage (gradient). Trilogy Tx was more efficient than Halcyon in the lung SBRT beam delivery process in terms of the total number of monitor units, modulation factor, and beam-on time. However, it was feasible to achieve a dose distribution that met SBRT plan requirements using Halcyon, with no significant differences in satisfying organs at risk dose constraints between both plans. Conclusions: Results confirm that Halcyon is a viable alternative for performing lung SBRT in the absence of a LINAC equipped with HD-MLC. However, extra consideration should be taken in determining whether to use Halcyon when the planning target volume setting is enormous, as in the case of significant tumor motions.

• The Journal of Korean Society for Radiation Therapy
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• v.23 no.1
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• pp.13-19
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• 2011

Purpose: It's essential to minimize the tumor motion and identify the exact location of the lesions to achieve the improvement in radiation therapy efficiency during SBRT. In this study, we made the established compression belt to reduce respiratory motion and evaluated the usefulness of clinical application in SBRT. Materials and Methods: We analyzed the merits and demerits of the established compression belt to reduce the respiratory motion and improved the reproducibility and precision in use. To evaluate the usefulness of improved compression belt for respiratory motion reduction in SBRT, firstly, we reviewed the spiral CT images acquired in inspiration and expiration states of 8 lung cancer cases, respectively, and analyzed the three dimensional tumor motion related to respiration. To evaluate isodose distribution, secondly, we also made the special phantom using EBT2 film (Gafchronic, ISP, USA) and we prepared the robot (Cartesian Robot-2 Axis, FARARCM4H, Samsung Mechatronics, Korea) to reproduce three dimensional tumor motion. And analysis was made for isodose curves and two dimensional isodose profiles with reproducibility of respiratory motion on the basis of CT images. Results: A respiratory motion reduction compression belt (Velcro type) that has convenient use and good reproducibility was developed. The moving differences of three dimensional tumor motion of lung cancer cases analyzed by CT images were mean 3.2 mm, 4.3 mm and 13 mm each in LR, AP and CC directions. The result of characteristic change in dose distribution using the phantom and rectangular coordinates robot showed that the distortion of isodose has great differences, mean length was 4.2 mm; the differences were 8.0% and 16.8% each for cranio-caudal and 8.1% and 10.9% each for left-right directions in underdose below the prescribed dose. Conclusion: In this study, we could develop the convenient and efficient compression belt that can make the organs' motion minimize. With this compression belt, we confirmed that underdose due to respiration can be coped with when CTV-PTV margins of mean 6 mm would be used. And we conclude that the respiratory motion reduction compression belt we developed can be used for clinical effective aids along with the gating system.

• The Journal of Korean Society for Radiation Therapy
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• v.19 no.2
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• pp.107-112
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• 2007

Purpose: The pelvic phantom was fabricated in the following purposes: (1) Dose verification of IMRT plan using Eclipse planning computer, (2) to study the interface effect at the interface between rectal wall and air. The TLD can be inserted in the pelvic phantom to confirm the dose distribution as well as uncertainty at the interface. Materials and Methods: A pelvic phantom with the dimension of 30 cm diameter, 20 cm height and 20 cm thickness was fabricated to investigate the dose at the rectal wall. The phantom was filled with water and has many features like bladder, rectum, and prostate and seminal vesicle (SV). The rectum is made of 3 cm-dimater plastic pipe, and it cab be blocked by using a plug, and film can be inserted around the rectal wall. The phantom was scanned with Philips Brillance scanner and various organs such as prostate, SV, and rectal wall, and bladder wall were delineated. The treatment parameters used in this study are the same as those used in the protocols in the SNUH. TLD chips are inserted to the phantom to evaluate the dose distribution to the rectal wall (to simulate high dose gradient region), bladder wall and SV (to simulate the high dose region) and 2 spots in anterior surface (to simulate the low dose region). The TLD readings are compared with those of the planning computer (ECLIPSE, Varian, USA). Results: The target TLD doses represented as the prostate and SV show excellent agreements with the doses from the RTP within +/-3%. The rectal wall doses measured at the rectal wall are different from the those of the RTP by -11%. This is in literatures called as an interface effect. The underdosages at the rectal wall is independent of 3 heterogeneity correction algorithm in the Eclipse RTP. Also the low dose regions s represented as surface in this study were within +/-1%. Conclusion: The RTP estimate the dosage very accurately withihn +/-3% in the high dose (SV, or prostate) and low dose region (surface). However, the dosage at the rectal wall differed by as much as 11% (In literatures, the underdosage of 9$\sim$15% were reported). This range of errors occurs at the interface, for example, at the interface between lung and chest wall, or vocal cord. This interface effect is very important in clinical situations, for example, to estimate the NTCP (normal tissue complication probability) and to estimate the limitations of the current RTP system. Monte-carlo-based RTP will handle this issue correctly.

• The Journal of Korean Society for Radiation Therapy
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• v.18 no.2
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• pp.113-117
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• 2006

Purpose: Post-mastectomy radiotherapy (PMR) is known to decrease loco-regional recurrence. Adequate skin and dermal dose are achieved by adding bolus. The more difficult clinical issue is determining the necessary number of bolus treatment, given the limits of normal skin tolerance. The aim of this study is to evaluate the necessary number of bolus treatment after PMR in patients with breast cancer. Materials and Methods: Four female breast cancer patients were included in the study. The median age was 53 years(range, $38{\sim}74$), tumor were left sided in 2 patients and right sided in 2patients. All patients were treated with postoperative radiotherapy after MRM. Radiotherapy was delivered to the chest wall (C.W) and supraclavicular lymph nodes (SCL) using 4 MV X-ray. The total dose was 50 Gy, in 2 Gy fractions (with 5 times a week). CT was peformed for treatment planning, treatment planning was peformed using $ADAC-Pinnacles^3$ (Phillips, USA) for all patients without and with bolus. Bolus treatment plans were generated using image tool (0.5 cm of thickness and 6 cm of width). Dose distribution was analyzed and the increased skin dose rate in the build-up region was computed and the skin dose using TLD-100 chips (Harshaw, USA) was measured. Results: No significant difference was found in dose distribution without and with bolus; C.W coverage was $95{\sim}100%$ of the prescribed dose in both. But, there was remarkable difference in the skin dose to the scar. The skin dose to the scar without and with bolus were $100{\sim}105%\;and\;50{\sim}75%$. The increased skin dose rates in the build-up region for Pt. 1, Pt. 2. Pt. 3 and Pt. 4 were 23.3%, 35.6%, 34.9%, and 41.7%. The results of measured skin dose using TLD-100 chips in the cases without and with bolus were 209.3 cGy and 161.1 cGy, 200 cGy and 150.2 cGy, 211.4 cGy and 160.5 cGy, 198.6 cGy and 155.5 cGy for Pt. 1, Pt. 2, Pt. 3, and Pt. 4. Conclusion: It was concludes through this analysis that the adequate number of bolus treatments is 50-60% of the treatment program. Further, clinical trial is needed to evaluate the benefit and toxicity associated with the use of bolus in PMR.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.1
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• pp.24-27
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• 2010

Purpose: Early diagnosis of breast is of the utmost importance to improve prognosis. We have a limitation for mammography and sonography detecting small cancer. Clinical importance of Breast Specific Gamma Imaging (BSGI) has improved for that reason. So We studied performance evaluation test of count rate and resolution with high sensitivity to the low dose of BSGI. Materials and Methods: BSGI of Dilon 6800, point source of $^{99m}Tc$ from 1.85~148 MBq (0.05~4 mCi) at the intervals of 1.85~37 MBq (0.05~1 mCi) was used for the test. Performance evaluation method was performed for measuring deadtime for choosing at the 5 different point in the useful field of view (UFOV), acquired image for 60 seconds. Compared with reference of clinical uptake distribution of breast, activity increased according to the distance change 10, 20, 30, 40, 50 mm in the useful field of view. Results: Counting curve increased according to the activity from 1.85 MBq (0.05 mCi) to the 74 MBq (2 mCi), and it change flat shape over 74 MBq (2 mCi). The variation of the full width of half maximum (FWHM) to the distance is 4.05, 4.73, 5.77, 6.90, 8.00, 9.32 mm in 1.85 MBq (0.05 mCi), 4.30, 4.80, 5.90, 7.00, 8.10, 9.07 mm in 3.7 MBq (0.1 mCi), 4.90, 5.60, 6.20, 7.20, 8.20, 9.10 mm in 5.55 MBq (0.15 mCi), 5.30, 6.10, 6.60, 7.00, 7.90, 8.70 mm in 7.40 MBq (0.2 mCi). Conclusion: Distortions of image would be acquired because of the deadtime in BSGI. We found out the fact that specification of $^{99m}Tc$ reaction under 74 MBq (2 mCi) for BSGI. Second, FWHM distribution change from varied distance from the detector, clearly distinguished the location of the lesion.

• The Journal of Korean Society for Radiation Therapy
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• v.16 no.1
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• pp.91-99
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• 2004

Purpose : For the head and neck radiotherapy, abutting photon field with electron field is frequently used for the irradiation of posterior neck when tolerable dose on spinal cord has been reached. Materials and methods : Using 6 MV X-ray and 9 MeV electron beams of Clinac1800(Varian, USA) linear accelerator, we performed film dosimetry by the X-OMAT V film of Kodak in solid water phantom according to depths(0 cm, 1.5 cm, 3 cm, 5 cm). 6 MV X-ray and 9 MeV electron(1Gy) were exposes to 8cm depth and surface(SSD 100cm) of phantom. The dose distribution to the junction line between photon($10cm{\times}10cm$ field with block) and electron($15cm{\times}15cm$ field with block) fields was also measured according to depths(0 cm, 0.5 1.5 cm, 3 cm, 5 cm). Results : At the junction line between photon and electron fields, the hot spot was developed on the side of the photon field and a cold spot was developed on that of the electron field. The hot spot in the photon side was developed at depth 1.5 cm with 7 mm width. The maximum dose of hot spot was increased to $6\%$ of reference doses in the photon field. The cold spot in the electron side was developed at all measured depths(0.5 cm-3 cm) with 1-12.5 mm widths. The decreased dose in the cold spot was $4.5-30\%$ of reference dose in the electron field. Conclusion : When we make use of abutting photon field with electron field for the treatment of head and neck cancer we should consider the hot and cold dose area in the junction of photon and electron field according to location of tumor.

• Progress in Medical Physics
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• v.23 no.4
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• pp.269-278
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• 2012

Aquaplast Thermoplastic (AT) is a tissue-equivalent oral compensator that has been developed to improve dose uniformity at the common boundary and around the treated area during radiotherapy in patients with head and neck cancer. In order to assess the usefulness of AT, the degree of improvement in dose distribution and physical properties were compared to those of oral compensators made using paraffin, alginate, and putty, which are materials conventionally used in dental imprinting. To assess the physical properties, strength evaluations (compression and drop evaluations) and natural deformation evaluations (volume change over time) were performed; a Gafchromic EBT2 film and a glass dosimeter inserted into a developed phantom for dose verification were used to measure the common boundary dose and the beam profile to assess the dose delivery. When the natural deformation of the oral compensators was assessed over a two-month period, alginate exhibited a maximum of 80% change in volume from moisture evaporation, while the remaining tissue-equivalent properties, including those of AT, showed a change in volume that was less than 3%. In a free-fall test at a height of 1.5 m (repeated 5 times as a strength evaluation), paraffin was easily damaged by the impact, but AT exhibited no damage from the fall. In compressive strength testing, AT was not destroyed even at 8 times the force needed for paraffin. In dose verification using a glass dosimeter, the results showed that in a single test, the tissue-equivalent (about 80 Hounsfield Units [HU]) AT delivered about 4.9% lower surface dose in terms of delivery of an output coefficient (monitor unit), which was 4% lower than putty and exhibited a value of about 1,000 HU or higher during a dose delivery of the same formulation. In addition, when the incident direction of the beam was used as a reference, the uniformity of the dose, as assessed from the beam profile at the boundary after passing through the oral compensators, was 11.41, 3.98, and 4.30 for air, AT, and putty, respectively. The AT oral compensator had a higher strength and lower probability of material transformation than the oral compensators conventionally used as a tissue-equivalent material, and a uniform dose distribution was successfully formed at the boundary and surrounding area including the mouth. It was also possible to deliver a uniformly formulated dose and reduce the skin dose delivery.