• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.3
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• pp.44-51
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• 2009

It is very important to verify generated setup errors in cancer therapy by using a high energy radiation and to perform the precise radiation therapy. Specially, the verification of treatment position is very crucial in special therapies like fractionated stereotatic radiotherapy (FSRT). The FSRT uses normally high-dose, small field size for treating small intracranial lesions. To estimate the developed FSRT system, the isocenter accuracy of gantry, couch and collimator were performed and a total of inaccuracy was less than ${\pm}1mm$. Precise beam targeting is crucial when using high-dose, small field size FSRT for treating small intracranial lesions. The EPID image of the 3mm lead ball mounted on the isocenter with a 25mm collimator cone was acquired and detected to the extent of one pixel (0.76mm) after comparing the difference between the center of a 25mm collimator cone and a 3 mm ball after processing the EPID image. In this paper, the radiation treatment efficiency can be improved by performing precise radiation therapy with a developed video based EPID and FSRT at near real time

• Radiation Oncology Journal
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• v.21 no.1
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• pp.10-18
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• 2003

Purpose : To evaluate the role of fractlonated sterotactic radiotherapy (FSRT) in the management of benign brain tumors, we reviewed the clinical, and radiographic responses of patients treated. Methods and Materials : Between March 1995 and March 2002, 36 patients with benign brain tumors were treated by FSRT. The pathological diagnoses consisted of pituitary adenomas (12 patients), cranio-pharyngiomas (5 patients), meningiomas (10 patients), and acoustic neurinomas (9 patients). Radiotherapy doses of 25 to 35 Gy (3~6 Gy/fraction, 5~10 fractions) were prescribed to the 85~90% isodose line, depending upon the location, size and volume of the tumors. The median clinical and radiographical follow up periods were 31 (range, 2~74) and 21 (range, 4~56) months, respectively. Results : In the 35 patients that could be evaluated for their clinical response, 13 (37.1%) were considered improved, 16 (45.7%) stable and 6 (17.2%) worse. Of the 33 patients who had radiographic studies, tumor shrinkage was noted in 17 (51.5%), tumor stabilization in 13 (39.4%), and tumor progression in 3 (9.1%). Of the 17 tumor shrinkage patients, 7 (21.2%) showed a complete response. Acute radiation-induced complications occurred iin 11 (30.6%) patients. Conclusions : FSRT is considered a safe and effective treatment method for begin brain tumors, but large numbers of patients, with relatively long follow-up periods are needed to assess the exact role or effect of FSRT.

• Progress in Medical Physics
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• v.13 no.1
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• pp.9-14
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• 2002

We invented the newly developed Fractionated Stereotactic Radiotherapy(F.S.R.T) system using combined techniques of couch mounting and pedestal mounting system. Head fixation frame consists of a milled alluminium alloy(duralumin) and is placed to the couch. This frame immobilized patient head using the dental bite, 3.2 mm frontal and occipital thermoplastic mask. To evaluate the coordinate of target isocenter, Brown-Revert-Walls C.T localizer can be attached to this frame. And also, we developed the frame mounting system by developing the modification of pedestal mounting system. This system is fixed to couch floor and can be used to evaluate the isocenteric accuracy of gantry, couch and collimator in Q.A procedure. In order to measure the relocation accuracy, the acrylic phantom and the accurate pointers have been made. The repositioning of the targets in the phantom were estimated by comparing C.T coordinates and E.C.L portal films taken with anterior-posterior and right-left direction. From the results of experiments, the average distance errors between the target isocenter and its mean position were 0.71$\pm$0.19 for lateral, 0.45$\pm$0.15 for inferior-superior, 0.63$\pm$0.18 for anterior-posterior. And the maximum distance error was less than 1.3 mm. The new head fixation frame and frame mounting system were non-invasive, accurately relocatable, easy to use, very light and well tolerable by the results of phantom tests. The major advantage of using this frame mounting system is complete access to any point in the Patients cranium especially posterior direction

• Radiation Oncology Journal
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• v.15 no.1
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• pp.19-26
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• 1997

Purpose : This study is to report experience with Fractionated Stereotactic Radiation Therapy (FSRT) for locally recurrent nasopharynx cancer after curative conventional radiation therapy. Materials and Methods : Three Patients with locally recurrent and symptomatic nasopharynx cancer were given FSRT as reirradiation method between the Period of September of 1995 and August of 1996 For two Patients, application of FSRT is their third radiation therapy directed to the nasopharynx. Two patients were given low dose chemotherapy as radiation sensitizer concurrently with FSRT Authors used 3-dimensional coordinate system by individually made, relocatable Gill-Thomas-Cosman (GTC) stereotactic frame and multiple non-coplanar arc therapy dose Planning was done using Xknife-3. Total of 45 Gy/18 fractions or 50 Gy/20 fractions were given. Results : Authors observed satisfactory symptomatic improvement and remarkable objective tumor size decrease by follow-up MR images taken 1 month Post-FSRT in ali three patients, while no neurologic side effect attributable to reirradiation was noticed. Two died at 7 and 9 months with loco-regional and distant seeding outside FSRT field, while one patient is living for 4 month. Conclusion Authors experienced satisfactory therapeutic effectiveness and safety of FSRT as reirradiatlon method for locally recurrent nasopharynx cancer Development of more effective systemic chemotherapeutic regimen is desired for distant metastasis

• The Journal of Korean Society for Radiation Therapy
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• v.11 no.1
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• pp.11-15
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• 1999

• The Journal of Korean Society for Radiation Therapy
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• v.11 no.1
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• pp.38-42
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• 1999

• 대한방사선치료학회:학술대회논문집
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• 1999.05a
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• pp.15-16
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• 1999

• The Journal of Korean Society for Radiation Therapy
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• v.11 no.1
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• pp.94-99
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• 1999

• The Journal of Korean Society for Radiation Therapy
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• v.27 no.1
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• pp.79-86
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• 2015

Purpose : The purpose of this study was to determine the proper treatment time of stereotactic body radiation therapy for spine metastasis cancer by using the image guidance system of CyberKnife(Accuray Incorporated, USA) which is able to correct movements of patients during the treatment. Materials and Methods : Fifty seven spine metastasis cancer patients who have stereotactic body radiation therapy of CyberKnife participate, 8 of them with cervical spine cancer, 26 of them with thoracic spine cancer, and 23 of them with lumbar spine cancer. X-ray images acquired during the treatment were classified by treatment site. From the starting point of treatment, motion tendency of patients is analyzed in each section which is divided into every 5 minutes. Results : In case of cervical spine, there is sudden increase of variation in 15 minutes after the treatment starts in rotational direction. In case of thoracic spine, there is no significantly variable section. However, variation increases gradually with the passage of time so that it is assumed that noticeable value comes up in approximately 40 minutes. In case of lumbar spine, sharp increase of variation is seen in 20 minutes in translational and rotational direction. Conclusion : Without having corrections during the treatment, proper treatment time is considered as less than 15 minutes for cervical spine, 40 minutes for thoracic spine, and 20 minutes for lumbar spine. If treatment time is longer than these duration, additional patient alignments are required or PTV margin should be enlarged.

• Progress in Medical Physics
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• v.26 no.4
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• pp.229-233
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• 2015

We retrospectively reviewed lung cancer patients who were treated with stereotactic ablative radiotherapy (SABR). We investigated the value of response evaluation after treatment by measuring the volume change of tumors on serial chest computed tomography (CT) examinations. The study included 11 consecutive patients with early-stage (T1-T2aN0M0) non-small cell lung cancer (NSCLC) who were treated with SABR. The median dose of SABR was 6,000 cGy (range 5,000~6,400) in five fractions. Sequential follow-up was performed with chest CT scans. Median follow-up time was 28 months. Radiologic measurement was performed on 51 CT scans with a median of 3 CT scans per patient. The median time to partial response ($T_{PR}$) was 3 months and median time to complete remission ($T_{CR}$) was 5 months. Overall response rate was 90.9% (10/11). Five patients had complete remission, five had partial response, and one patient developed progressive disease without response. On follow-up, three patients (27.2%) developed progressive disease after treatment. We evaluated the the response after SABR. Our data also showed the timing of response after SABR.