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Featured researches published by Dahl Park.


International Journal of Radiation Oncology Biology Physics | 2009

C-REACTIVE PROTEIN LEVELS AND RADIATION-INDUCED MUCOSITIS IN PATIENTS WITH HEAD-AND-NECK CANCER

Yongkan Ki; Wontaek Kim; Jiho Nam; Dong-Hyun Kim; Dahl Park; Dong Won Kim

PURPOSE To evaluate the relationship between C-reactive protein (CRP) levels or the erythrocyte sedimentation rate (ESR) and the grade of acute radiation-induced mucositis in patients with head-and-neck cancer. METHODS AND MATERIALS This study was performed in 40 patients who received intensity-modulated radiation therapy as a radical treatment of primary laryngo-pharyngeal cancer. Serum CRP level and ESR were initially checked on the day of radiotherapy simulation and were measured every week during the irradiation schedule and two times biweekly after radiotherapy. Mucosal reactions were evaluated by radiation oncologists on days of blood sampling. RESULTS The distribution of the most severe mucositis was Grade I mucositis in 10% of the patients, Grade II in 60% of the patients and Grade III in 30% of the patients. Statistical analysis indicated a significant rise in the CRP level (p < 0.001) according to radiation fraction number and grade of mucositis. A change of the mean CRP level was correlated with progression of mean grade of mucositis according to fraction number. The ESR did not show any statistically significant relationship with radiotherapy fraction number and grade of acute mucositis. CONCLUSIONS There was a significant correlation between the presence of acute mucositis and CRP level in this study. The CRP level could be conveniently determined along with evaluation of mucosal reactions during or after radiotherapy to provide further information on radiation-induced mucositis.


Radiation oncology journal | 2013

Short-course palliative radiotherapy for uterine cervical cancer.

Dong-Hyun Kim; Ju Hye Lee; Yong Kan Ki; Ji Ho Nam; Won Taek Kim; Ho Sang Jeon; Dahl Park; Dong Won Kim

Purpose The purpose of this retrospective study was to evaluate the efficacy and feasibility of short-course hypofractionated radiotherapy (RT) for the palliation of uterine cervical cancer. Materials and Methods Seventeen patients with cancer of the uterine cervix, who underwent palliative hypofractionated 3-dimensional conformal radiotherapy between January 2002 and June 2012, were retrospectively analyzed. RT was delivered to symptomatic lesions (both the primary mass and/or metastatic regional lymph nodes). The total dose was 20 to 25 Gy (median, 25 Gy) in 5 Gy daily fractions. Results The median follow-up duration was 12.2 months (range, 4 to 24 months). The median survival time was 7.8 months (range, 4 to 24 months). Vaginal bleeding was the most common presenting symptom followed by pelvic pain (9 patients). The overall response rates were 93.8% and 66.7% for vaginal bleeding control and pelvic pain, respectively. Nine patients did not have any acute side effects and 7 patients showed minor gastrointestinal toxicity. Only 1 patient had grade 3 diarrhea 1 week after completion of treatment, which was successfully treated conservatively. Late complications occurred in 4 patients; however, none of these were of grade 3 or higher severity. Conclusion Short-course hypofractionated RT was effective and well tolerated as palliative treatment for uterine cervical cancer.


International Journal of Radiation Oncology Biology Physics | 2013

Probiotics for Rectal Volume Variation During Radiation Therapy for Prostate Cancer

Yongkan Ki; Wontaek Kim; Jiho Nam; Dong-Hyun Kim; Juhye Lee; Dahl Park; Hosang Jeon; Honggu Ha; Tae-Nam Kim; Dong Won Kim

PURPOSE To investigate the effect of the probiotic Lactobacillus acidophilus on the percentage volume change of the rectum (PVCR), a crucial factor of prostate movement. METHODS AND MATERIALS Prostate cancer patients managed with tomotherapy as a radical treatment were enrolled in the study to take a probiotic capsule containing 1.0×10(8) colony-forming units of L acidophilus or a placebo capsule twice daily. Radiation therapy was performed at a dose of 78 Gy in 39 fractions. The PVCR, defined as the difference in rectal volume between the planning computed tomographic (CT) and daily megavoltage CT images, was analyzed. RESULTS Forty patients were randomized into 2 groups. The L acidophilus group showed significantly lower median rectal volume and median PVCR values than the placebo group. L acidophilus showed a significant reduction effect on the PVCR (P<.001). However, the radiation therapy fraction number did not significantly influence the PVCR. CONCLUSIONS L acidophilus was useful in reducing the PVCR, which is the most important determining factor of prostate position, during radiation therapy for prostate cancer.


International Journal of Gynecological Cancer | 2016

Maximum Standardized Uptake Value of Pelvic Lymph Nodes in [18F]-Fluorodeoxyglucose Positron Emission Tomography Is a Prognostic Factor for Para-Aortic Lymph Node Recurrence in Pelvic Node-Positive Cervical Cancer Treated With Definitive Chemoradiotherapy.

Dong-Hyun Kim; Won Taek Kim; Jin Suk Bae; Yong Kan Ki; Dahl Park; Dong Soo Suh; Ki Hyung Kim; Joo Hye Lee; Ja Young Lee; Ho Sang Jeon; Ji Ho Nam

Objectives This study aimed to identify prognostic factors for para-aortic lymph node (PALN) recurrence and their effect on survival outcomes in patients with pelvic node–positive squamous cell carcinoma (SCC) of the cervix treated with definitive concurrent chemoradiotherapy (CCRT). Materials and Methods Of the 116 patients with biopsy-proven SCC of the uterine cervix who underwent primary CCRT from 2007 to 2012, 48 patients with pelvic LN metastasis detected by [18F]-fluorodeoxyglucose positron emission tomography (FDG PET) were retrospectively analyzed. Patients with evidence of para-aortic lymphadenopathy were excluded. The whole pelvis was the standard irradiation field for all patients. The associations of age, stage, serum SCC antigen (SCC-Ag) level, maximum standardized uptake value (SUVmax), hemoglobin level, overall treatment time, adjuvant chemotherapy, and pelvic LN status with PALN recurrence and survival outcomes were evaluated. Results At a median follow-up of 34.0 months (range, 8–73 months), 10 (20.8%) patients had developed PALN recurrences. The relationship between pelvic LN FDG uptake and PALN recurrence was evaluated by the cutoff value (SUVmax = 3.85) determined by receiver operating characteristic curve analysis. The independent risk factors for PALN recurrence were FDG-avid pelvic LN (SUVPLN) greater than 3.85 (hazard ratio, 13.12; P = 0.025) and posttreatment SCC-Ag level greater than 2.0 (ng/mL) (hazard ratio, 20.69; P = 0.019). Patients with an SUVPLN greater than 3.85 were found to have significantly worse 5-year distant metastasis-free (51.0% vs 79.0%, P = 0.016) and progression-free survival (38.7% vs 67.3%, P = 0.011) than those with an SUVPLN less than or equal to 3.85. Conclusions SUVPLN is a statistically significant prognostic factor of PALN recurrence and survival after definitive CCRT for pelvic node–positive SCC of the uterine cervix.


Radiation oncology journal | 2017

The role of surgical clips in the evaluation of interfractional uncertainty for treatment of hepatobiliary and pancreatic cancer with postoperative radiotherapy

Jin Suk Bae; Dong-Hyun Kim; Won Taek Kim; Yong Ho Kim; Dahl Park; Yong Kan Ki

Purpose To evaluate the utility of implanted surgical clips for detecting interfractional errors in the treatment of hepatobiliary and pancreatic cancer with postoperative radiotherapy (PORT). Methods and Materials Twenty patients had been treated with PORT for locally advanced hepatobiliary or pancreatic cancer, from November 2014 to April 2016. Patients underwent computed tomography simulation and were treated in expiratory breathing phase. During treatment, orthogonal kilovoltage (kV) imaging was taken twice a week, and isocenter shifts were made to match bony anatomy. The difference in position of clips between kV images and digitally reconstructed radiographs was determined. Clips were consist of 3 proximal clips (clip_p, ≤2 cm) and 3 distal clips (clip_d, >2 cm), which were classified according to distance from treatment center. The interfractional displacements of clips were measured in the superior-inferior (SI), anterior-posterior (AP), and right-left (RL) directions. Results The translocation of clip was well correlated with diaphragm movement in 90.4% (190/210) of all images. The clip position errors greater than 5 mm were observed in 26.0% in SI, 1.8% in AP, and 5.4% in RL directions, respectively. Moreover, the clip position errors greater than 10 mm were observed in 1.9% in SI, 0.2% in AP, and 0.2% in RL directions, despite respiratory control. Conclusion Quantitative analysis of surgical clip displacement reflect respiratory motion, setup errors and postoperative change of intraabdominal organ position. Furthermore, position of clips is distinguished easily in verification images. The identification of the surgical clip position may lead to a significant improvement in the accuracy of upper abdominal radiation therapy.


Radiation oncology journal | 2013

Neoadjuvant intra-arterial chemotherapy combined with radiotherapy and surgery in patients with advanced maxillary sinus cancer

Won Taek Kim; Jiho Nam; Yong Kan Ki; Ju Hye Lee; Dong-Hyun Kim; Dahl Park; Kyu Sup Cho; Hwan Jung Roh; Dong Won Kim

Purpose The optimal treatment of advanced maxillary sinus cancer has been challenging for several decades. Intra-arterial chemotherapy (IAC) for head and neck cancer has been controversial. We have analyzed the long-term outcome of neoadjuvant IAC followed by radiation therapy (RT) and surgery. Materials and Methods Twenty-seven patients with advanced maxillary sinus cancer were treated between 1989 and 2002. Five-fluorouracil (5-FU, 500 mg/m2) was infused intra-arterially, and followed by RT (total 50.4 Gy/28 fractions). A planned surgery was performed 3 to 4 weeks after completion of IAC and RT. Results At a median follow-up of 77 months (range, 12 to 169 months), the 5-year rates of overall survival in all patients were 63%. The 5-year rates of overall survival of stage T3/T4 patients were 70.0% and 58.8%, respectively. Seven of fourteen patients with disease recurrence had a local recurrence alone. The 5-year actuarial local control rates in patients with stage T3/T4, and in all patients were 20.0%, 32.3%, and 27.4%, respectively. Overall response rate after the completion of IAC and RT was 70.3%. During the follow-up, seven patients (25.9%) showed mild to moderate late complications. The tumor extent (i.e., the involvement of either orbit and/or base of skull) appeared to be related with local recurrence. Conclusion Neoadjuvant IAC with 5-FU followed by RT and surgery may be effective to improve local tumor control in the patients with advanced maxillary sinus cancer. However, local failure was still the major cause of death. Further investigations are required to determine the optimal treatment schedule, radiotherapy techniques and chemotherapy regimens.


International Journal of Radiation Oncology Biology Physics | 2011

Fractionated Wide-Field Radiation Therapy Followed by Fractionated Local-Field Irradiation for Treating Widespread Painful Bone Metastasis

Yongkan Ki; Wontaek Kim; Jiho Nam; Dong-Hyun Kim; Hosang Jeon; Dahl Park; Dong Won Kim

PURPOSE Wide-field radiation therapy (WFRT) is an effective treatment for widespread bone metastasis. We evaluated local-field irradiation (LFI) after fractionated WFRT (f-WFRT) for treating the patients with multiple painful bone lesions. METHODS AND MATERIALS From 1998 to 2007, 32 patients with multiple bone metastases were treated with fractionated LFI (f-LFI) after f-WFRT. All patients initially received 15 Gy in 5 fractions to a wide field, followed by LFI (9-15 Gy in 3 Gy fractions). Response was assessed by evaluating the degree of pain relief using a visual analog scale before radiotherapy, after f-WFRT, and after f-LFI. RESULTS Fractionated LFI following f-WFRT yielded an overall relief rate of 93.8% and a complete relief rate of 43.8%. The rate of the appearance of new disease was 6.3% for the patients with complete relief, 20.5% for the patients with a partial relief, and 50% for the patients with no relief. CONCLUSION Fractionated LFI after f-WFRT is a well-tolerated and effective treatment for multiple metastatic bone disease.


Journal of Korean Medical Science | 2017

Effect of Coenzyme Q10 on Radiation Nephropathy in Rats

Yongkan Ki; Wontaek Kim; Yong Ho Kim; Dong-Hyun Kim; Jin Sook Bae; Dahl Park; Hosang Jeon; Ju Hye Lee; Jayoung Lee; Jiho Nam

The kidney is one of the most radiosensitive organs in the abdominal cavity and is the dose-limiting structure in cancer patients receiving abdominal or total body irradiation. In the present study, the effect of coenzyme Q10 (CoQ10) on radiation nephropathy was evaluated in rats. A total of 72 rats were equally randomized into 4 groups: Control, CoQ10, irradiation with 10 Gy (RT) + placebo, or RT + CoQ10. The 2 RT groups received single 10 Gy of abdominal irradiation. The 2 CoQ10 groups were supplemented daily with 1 mL of soybean oil containing 10 mg/kg of CoQ10. The RT + placebo and control groups received same dose of soybean oil. After 24 weeks, laboratory and histopathologic findings were compared. The 2 RT groups showed significant increases in blood urea nitrogen (BUN) and creatinine levels and significant pathologic changes such as glomerulosclerosis and tubulointerstitial fibrosis. CoQ10 supplementation resulted in significant reductions of BUN and creatinine levels compared with the RT + placebo group (P < 0.001 and P = 0.038, respectively). CoQ10 treatment significantly attenuated glomerular and tubular changes of irradiated kidney in semiquantitative analysis (P < 0.001 for both). Administration of CoQ10 can alleviate the radiation-induced nephropathy.


Radiation oncology journal | 2018

Adjuvant external beam radiation and brachytherapy for vaginal resection margin positive cervical cancer

Dong-Hyun Kim; Yongkan Ki; Wontaek Kim; Dahl Park; Joohye Lee; Ja-Young Lee; Hosang Jeon; Jiho Nam

Purpose To evaluate the treatment outcomes of adjuvant external beam radiation therapy (EBRT) and vaginal brachytherapy (VB) following radical hysterectomy in cervical cancer patients with involved vaginal resection margin (VRM). Materials and Methods We retrospectively reviewed the medical records of 21 patients treated with postoperative EBRT and VB for positive VRM FIGO stage IB–IIA cervical cancer between 2003 and 2015. Concurrent platinum-based chemotherapy was administered to all patients. Results The median whole pelvis EBRT dose was 50.4 Gy (range, 45 to 50.4 Gy). In the VB, the median dose per fraction, number of fractions, and total dose delivered were: 4 Gy (range, 3.0 to 4.0 Gy), 4 fractions (range, 3 to 5 fractions), and 16 Gy (range, 12 to 20 Gy), respectively. At a median follow-up of 46 months (range, 9 to 122 months), local recurrence was observed in 2 patients, and distant metastasis was present in 7 patients. All patients with local recurrence subsequently developed distant metastases. The 5-year local control, disease-free survival, and overall survival rates were 89.1%, 65.9%, and 62.9%, respectively. Of the 21 patients, 7 patients (33.3%) reported grade 2 acute toxicity; however, there were no grade 3 or higher acute adverse events. Grade 1–2 late toxicities were observed in 8 patients. Late grade 3 urinary toxicity was reported in 1 patient. conclusions Adjuvant EBRT and VB showed excellent local control and low toxicity in cervical cancer patients with positive VRM. Although limited by its retrospective nature, the findings from our study provide evidence supporting the use of additional VB in pathologically involved VRM.


PLOS ONE | 2017

Generation of polychromatic projection for dedicated breast computed tomography simulation using anthropomorphic numerical phantom

Hosang Jeon; Hanbean Youn; Jin Sung Kim; Jiho Nam; Jayoung Lee; Juhye Lee; Dahl Park; Wontaek Kim; Yongkan Ki; Dong-Hyun Kim

Numerical simulations are fundamental to the development of medical imaging systems because they can save time and effort in research and development. In this study, we developed a method of creating the virtual projection images that are necessary to study dedicated breast computed tomography (BCT) systems. Anthropomorphic software breast phantoms of the conventional compression type were synthesized and redesigned to meet the requirements of dedicated BCT systems. The internal structure of the breast was randomly constructed to develop the proposed phantom, enabling the internal structure of a naturally distributed real breast to be simulated. When using the existing monochromatic photon incidence assumption for projection-image generation, it is not possible to simulate various artifacts caused by the X-ray spectrum, such as the beam hardening effect. Consequently, the system performance could be overestimated. Therefore, we considered the polychromatic spectrum in the projection image generation process and verified the results. The proposed method is expected to be useful for the development and optimization of BCT systems.

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Dong-Hyun Kim

Pusan National University

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Yongkan Ki

Pusan National University

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Jiho Nam

Pusan National University

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Wontaek Kim

Pusan National University

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Hosang Jeon

Pusan National University

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Dong Won Kim

Pusan National University

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Won Taek Kim

Pusan National University

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Yong Ho Kim

Pusan National University

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Jayoung Lee

Pusan National University

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Ju Hye Lee

Pusan National University

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