• Journal of Korean Neurosurgical Society
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• v.45 no.3
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• pp.157-163
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• 2009

Objective : In recent years, CyberKnife has emerged as an important treatment modality in the management of pituitary adenomas. Treatment results after performing CyberKnife and the complications of this procedure are reviewed. Methods : Twenty-six patients with pituitary adenomas received stereotactic radiosurgery with the CyberKnife (CKRS). The follow-up periods ranged from 7 months to 47 months (mean$\pm$SD : $30{\pm}12.7$ months). The patients consisted of 17 with non-functioning adenomas, 3 with prolactinomas and 6 with acromegaly. The change in the tumor volume, visual acuity, hormonal function, and complications by this therapy were analyzed in each case. Results : The tumor control rate was 92.3%. Hormonal function was improved in all of the 9 (100%) functioning adenomas. Hormonal normalization was observed in 4 of the 9 (44%) patients with a mean duration of 16 months. In two patients (7.6%), visual acuity worsened due to cystic enlargement of the tumor after CKRS. No other complications were observed. Conclusion : CyberKnife is considered safe and effective in selected patients with pituitary adenomas. However, longer follow-up is required for a more complete assessment of late toxicity and treatment efficacy.

• Progress in Medical Physics
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• v.30 no.4
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• pp.94-103
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• 2019

Purpose: To evaluate the clinical feasibility of knowledge-based planning (KBP) for volumetric-modulated arc radiotherapy (VMAT) in spine stereotactic body radiotherapy (SBRT). Methods: Forty-eight VMAT plans for spine SBRT was studied. Two planning target volumes (PTVs) were defined for simultaneous integrated boost: PTV for boost (PTV-B: 27 Gy/3fractions) and PTV elective (PTV-E: 24 Gy/3fractions). The expert VMAT plans were manually generated by experienced planners. Twenty-six plans were used to train the KBP model using Varian RapidPlan. With the trained KBP model each KBP plan was automatically generated by an individual with little experience and compared with the expert plan (closed-loop validation). Twenty-two plans that had not been used for KBP model training were also compared with the KBP results (open-loop validation). Results: Although the minimal dose of PTV-B and PTV-E was lower and the maximal dose was higher than those of the expert plan, the difference was no larger than 0.7 Gy. In the closed-loop validation, D_1.2cc, D_0.35cc, and D_mean of the spinal cord was decreased by 0.9 Gy, 0.6 Gy, and 0.9 Gy, respectively, in the KBP plans (P<0.05). In the open-loop validation, only D_mean of the spinal cord was significantly decreased, by 0.5 Gy (P<0.05). Conclusions: The dose coverage and uniformity for PTV was slightly worse in the KBP for spine SBRT while the dose to the spinal cord was reduced, but the differences were small. Thus, inexperienced planners could easily generate a clinically feasible plan for spine SBRT by using KBP.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.146-149
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• 2002

The aim of stereotactic radiosurgery(SRS) is to deliver a high dose to a target region and a low dose to critical organ through only one or a few irradiation. To satisfy this aim, optimized irradiating conditions must be searched in the planning. Thus, many mathematical methods such as gradient method, simulated annealing and genetic algorithm had been proposed to find out the conditions automatically. There were some limitations using these methods: the long calculation time, and the difficulty of unique solution due to the different shape of tumor. In this study, optimization protocol using ideal models and data base was proposed. Proposed optimization protocol constitutes two steps. First step was a preliminary work. Some possible ideal geometry shapes, such as sphere, cylinder, cone shape or the combination, were assumed to approximate the real tumor shapes. Optimum variables such as isocenter position or collimator size, were determined so that the high dose region could be shaped to fit ideal models with the arrangement of multiple isocenter. Data base were formed with those results. Second, any shaped real targets were approximated to these models using geometry comparison. Then, optimum variables for ideal geometry were chosen from the data base predetermined, and final parameters were obtained by adjusting these data. Although the results of applying the data base to patients were not superior to the result of optimization in each case, it can be acceptable as a starting point of plan.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.9
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• pp.4233-4235
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• 2016

Background: Whole brain radiotherapy (WBRT) and stereotactic radiosurgery were frequently used to palliate patients with brain metastases. It remains controversial which modality or combination of therapy is superior especially in the setting of limited number of brain metastases. The availability of newer medical therapy that improves survival highlighted the importance of reducing long term radiation toxicity associated with WBRT. In this study, we aim to demonstrate the hippocampal sparing technique with whole brain and integrated simultaneous boost Materials and Methods: Planning data from 10 patients with 1-5 brain metastases treated with SRS were identified. Based on the contouring guideline from RTOG atlas, we identified and contoured the hippocampus with 5mm isocentric expansion to form the hippocampal avoidance structure. The plan was to deliver hippocampal sparing whole brain radiotherapy (HSWBRT) of 30 Gy in 10 fractions and simultaneous boost to metastatic lesions of 30 Gy in 10 fractions each. Results: The PTV, hippocampus and hippocampal avoidance volumes ranges between 1.00 - 39.00 cc., 2.50 - 5.30 cc and 26.47 - 36.30 cc respectively. The mean hippocampus dose for the HSWBRT and HSWBRT and SIB plans was 8.06 Gy and 12.47 respectively. The max dose of optic nerve, optic chiasm and brainstem were kept below acceptable range of 37.5 Gy. Conclusions: The findings from this dosimetric study demonstrated the feasibility and safety of treating limited brain metastases with HSWBRT and SIB. It is possible to achieve the best of both worlds by combining HSWBRT and SIB to achieve maximal local intracranial control while maintaining as low a dose as possible to the hippocampus thereby preserving memory and quality of life.

• Journal of Radiation Protection and Research
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• v.43 no.3
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• pp.107-113
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• 2018

Background: The purpose of our study was to compare the dosimetric advantages of Flattening filter free (FFF) beams for trigeminal neuralgia patients using 4 mm conical collimators over previously treated patients with 6 MV SRS beam. Materials and Methods: A retrospective study was conducted for 5 TN patients who had been previously treated at our institution using frame-based, LINAC-based stereotactic radiosurgery (SRS) on Novalis Tx using 6 MV SRS beam were replanned on 6X FFF beams on Edge Linear accelerator with same beam angles and dose constraints using 4 mm conical collimator. The total number of monitor units along with the beam on time was compared for both Edge and Novalis Tx by redelivering the plans in QA mode of LINAC to compare the delivery efficiency. Plan quality was evaluated by homogeneity index (HI) and Paddick gradient index (GI) for each plan. We also analyzed the doses to brainstem and organ at risks (OARs). Results and Discussion: A 28% beam-on time reduction was achieved using 6X FFF when compared with 6X SRS beam of Novalis Tx. A sharp dose fall off with gradient index value of $3.4{\pm}0.27$ for 4 mm Varian conical collimator while $4.17{\pm}0.20$ with BrainLab cone. Among the 5 patients treated with a 4 mm cone, average maximum brainstem dose was 10.24 Gy for Edge using 6X FFF and 14.28 Gy for Novalis Tx using 6X SRS beam. Conclusion: The use of FFF beams improves delivery efficiency and conical collimator reduces dose to OAR's for TN radiosurgery. Further investigation is warranted with larger sample patient data.

• Radiation Oncology Journal
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• v.37 no.3
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• pp.149-155
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• 2019

In metastatic non-small cell lung cancer (NSCLC), the role of radiotherapy (RT) has been limited to palliation to alleviate the symptoms. However, with the development of advanced RT techniques, recent advances in immuno-oncology therapy targeting programmed death 1 (PD-1) and programmed death ligand 1 (PD-L1) and targeted agents for epidermal growth factor receptor (EGFR) mutation or anaplastic lymphoma kinase (ALK) translocation allowed new roles of RT in these patients. Within this metastatic population, there is a subset of patients with a limited number of sites of metastatic disease, termed as oligometastasis that can achieve long-term survival from aggressive local management. There is no consensus on the definition of oligometastasis; however, most clinical trials define oligometastasis as having 3 to 5 metastatic lesions. Recent phase II randomized clinical trials have shown that ablative RT, including stereotactic ablative body radiotherapy (SABR) and hypofractionated RT, to primary and metastatic sites improved progression-free survival (PFS) and overall survival (OS) in patients with oligometastatic NSCLC. The PEMBRO-RT study, a randomized phase II study comparing SABR prior to pembrolizumab therapy and pembrolizumab therapy alone, revealed that the addition of SABR improved the overall response, PFS, and OS in patients with advanced NSCLC. The efficacy of RT in oligometastatic lung cancer has only been studied in phase II studies; therefore, large-scale phase III studies are needed to confirm the benefit of local ablative RT in patients with oligometastatic NSCLC. Local intensified RT to primary and metastatic lesions is expected to become an important treatment paradigm in the near future in patients with metastatic lung cancer.

• Journal of Korean Neurosurgical Society
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• v.46 no.3
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• pp.245-251
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• 2009

Objective : The authors analyzed the effectiveness and therapeutic response of Novalis shaped beam radiosurgery for metastatic brain tumors, and the prognostic factors which influenced the outcome. Methods : We performed a retrospective analysis of 106 patients who underwent 159 treatments for 640 metastatic brain lesions between January 2000 and April 2008. The pathologies of the primary tumor were mainly lung (45.3%), breast (18.2%) and GI tract (13.2%). We classified the patients using Radiation Therapy Oncology Group Recursive Partitioning Analysis (RPA) and then analyzed the survival and prognostic factors according to the Kaplan Meier method and univariate analysis. Results : The overall median actuarial survival rate was 7.3 months from the time of first radiosurgery treatment while 1 and 2 year actuarial survival estimates were 31% and 14.4%, respectively. Median actuarial survival rates for RPA classes I, II, and III were 31.3 months, 7.5 months and 1.7 months, respectively. Patients' life spans, higher Karnofsky performance scores and age correlated closely with RPA classes. However, sex and the number of lesions were not found to be significantly associated with length of survival. Conclusion : This result suggests that Novalis radiosurgery can be a good treatment option for treatment of the patients with brain metastases.

• Radiation Oncology Journal
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• v.36 no.2
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• pp.122-128
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• 2018

Purpose: To investigate positional uncertainty and its correlation with clinical parameters in spine stereotactic body radiotherapy (SBRT) using thermoplastic mask (TM) immobilization. Materials and Methods: A total of 21 patients who underwent spine SBRT for cervical or upper thoracic spinal lesions were retrospectively analyzed. All patients were treated with image guidance using cone beam computed tomography (CBCT) and 4 degrees-of-freedom (DoF) positional correction. Initial, pre-treatment, and post-treatment CBCTs were analyzed. Setup error (SE), pre-treatment residual error (preRE), post-treatment residual error (postRE), intrafraction motion before treatment (IM1), and intrafraction motion during treatment (IM2) were determined from 6 DoF manual rigid registration. Results: The three-dimensional (3D) magnitudes of translational uncertainties (mean ${\pm}$ 2 standard deviation) were $3.7{\pm}3.5mm$ (SE), $0.9{\pm}0.9mm$ (preRE), $1.2{\pm}1.5mm$ (postRE), $1.4{\pm}2.4mm$ (IM1), and $0.9{\pm}1.0mm$ (IM2), and average angular differences were $1.1^{\circ}{\pm}1.2^{\circ}$ (SE), $0.9^{\circ}{\pm}1.1^{\circ}$ (preRE), $0.9^{\circ}{\pm}1.1^{\circ}$ (postRE), $0.6^{\circ}{\pm}0.9^{\circ}$ (IM1), and $0.5^{\circ}{\pm}0.5^{\circ}$ (IM2). The 3D magnitude of SE, preRE, postRE, IM1, and IM2 exceeded 2 mm in 18, 0, 3, 3, and 1 patients, respectively. No association were found between all positional uncertainties and body mass index, pain score, and treatment location (p > 0.05, Mann-Whitney test). There was a tendency of intrafraction motion to increase with overall treatment time; however, the correlation was not statistically significant (p > 0.05, Spearman rank correlation test). Conclusion: In spine SBRT using TM immobilization, CBCT and 4 DoF alignment correction, a minimum residual translational uncertainty was 2 mm. Shortening overall treatment time and 6 DoF positional correction may further reduce positional uncertainties.

• Progress in Medical Physics
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• v.13 no.3
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• pp.135-138
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• 2002

Fractionated stereotactic radiosurguy (FSRS) requires precise and reproducible patient set up. For these reasons non-invasive mask fixation methods have been used in Linac based FSRS. In this study, we measured and assessed the isocenter reproducibility using a commercial head mask fixation system based on thermoplastic materials. For the verification and the measurement of isocenter deviation a special acrylic brain phantom was designed. The designed phantom has 22 vertical rods and each rod has different lengths. At the end of the 8 rods, the monochromic film is attached and irradiated due to planned target position. Deviations of isocenter were measured separately for each direction. The mean deviation showed 0.4 mm in longitudinal direction, 0.1 mm in the lateral direction, 0.1 mm in the anterior-posterior direction of the treatment couch. The data demonstrates the high accuracy and reproducibility. This study reinforces previous literature published.

• Journal of Korean Academy of Nursing
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• v.48 no.2
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• pp.221-231
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• 2018

Purpose: This study aimed to compare the effects of three interventions on pain, blood pressure, and pulse rate during infiltration anesthesia in patients about to undergo gamma knife surgeries. Methods: The three interventions employed in a university-affiliated Hospital in J City, South Korea were as follows: EMLA cream plus Vapocoolant spray (Vapocoolant, n=30), EMLA cream plus 10.0% Lidocaine spray (Lidocaine, n=30), and EMLA cream only (EMLA, n=30). The equivalent control-group pre test - post test study design was used. Pain was assessed subjectively using the numeric rating scale (NRS) and objectively using a Galvanic Skin Response (GSR) tester. NRS scores were assessed after infiltration anesthesia and the GSR was assessed during infiltration anesthesia. Blood pressure and pulse rate were assessed twice: before and after infiltration anesthesia. Data were collected between August 3, 2016 and March 24, 2017. Results: NRS scores after infiltration anesthesia and the GSR during infiltration anesthesia were significantly lower in the Vapocoolant group than in the Lidocaine and EMLA groups (F=13.56, p<.001 and F=14.43, p<.001, respectively). The increase in systolic blood pressure (F=4.77, p=.011) and in pulse rates (F=4.78, p=.011) before and after infiltration anesthesia were significantly smaller in the Vapocoolant group than in the Lidocaine and EMLA groups; however, no significant differences were observed in diastolic blood pressures (F=1.51, p=.227). Conclusion: EMLA cream plus Vapocoolant spray was the most effective intervention to relieve pain and to lower increase in systolic blood pressure and pulse rate caused by infiltration anesthesia for stereotactic frame fixation. Thus, application of Vapocoolant spray in addition to EMLA cream is highly recommended as a nursing intervention for patients undergoing gamma knife surgeries.