• Radiation Oncology Journal
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• v.13 no.4
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• pp.403-409
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• 1995

Purpose : Authors tried to enhance the safety and accuracy of radiosurgery by verifying stereotacitc target point in actual treatment position prior to irradiation. Materials and Methods : Before the actual treatment, several sections of anthropomorphic head phantom were used to create a condition of unknown coordinates of the target point. A film was sandwitched between the phantom sections and punctured by sharp needle tip. The tip of the needle represented the target point. The head phantom was fixed to the stereotactic ring and CT scan was done with CT localizer attached to the ring. After the CT scanning, the stereotactic coordinates of the target point were determined. The head phantom was secured to accelerator's treatment couch and the movement of laser isocenter to the stereotactic coordinates determined by CT scanning was performed using target positioner. Accelerator's anteroposterior and lateral portal films were taken using angiographic localizers. The stereotactic coordinates determined by analysis of portal films were compared with the stereotactic coordinates previously determined by CT scanning. Following the correction of discrepancy the head phantom was irradiated using a stereotactic technique of several arcs. After the irradiation, the film which was sandwitched between the phantom sections was developed and the degree of coincidence between the center of the radiation distribution with the target point represented by the hole in the film was measured. In the treatment of the actual patients, the way of determining the stereotactic coordinates with CT localizers and angiograuhic localizers was the same as the phantom study. After the correction of the discrepancy between two sets of coordinates, we proceeded to the irradiation of the actual patient. Results : In the phantom study, the agreement between the center of the radiation distribution and the localized target point was very good. By measuring optical density profiles of the sandwitched film along axes that intersected the target point, authors could confirm the discrepancy was 0.3 mm. In the treatment of an actual patient, the discrepancy between the stereotactic coordinates with CT localizers and angiographic localizers was 0.6 mm. Conclusion : By verifying stereotactic target point in actual treatment position prior to irradiation, the accuracy and safety of streotactic radiosurgery procedure were established.

• Clinical and Experimental Pediatrics
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• v.50 no.2
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• pp.198-204
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• 2007

Purpose : The hope that arresting pubertal developement might increase final adult height has led to an attempt to use GnRH agonist (GnRHa) in children with early puberty and poor growth prognosis. We investigated the growth-promoting effect of GnRH agonists with or without growth hormone (GH) in girls with early puberty and decreased predicted adult height (PAH). Methods : Thirty five girls with advanced bone age and early pubertal signs were randomized for treatment for about 1 year with monthly GnRHa in group 1 (n=18), or with a combination of GH and GnRHa in group 2 (n=17). The following growth parameters were compared between groups, and the difference ($\Delta$) before and after treatment : chronological age (CA), bone age (BA), $\Delta$(BA-CA), height (HT), target height (TH), predicted adult height (PAH), $\Delta$ (TH-PAH), serum insulin-like growth factor (IGF-1) and insulin-like growth factor binding protein (IGFBP-3). Results : Before treatment, BA, TH, PAH Standard deviation scores (SDS), $\Delta$(TH-PAH) were not different between the two groups, but CA was higher in group 2 and $\Delta$(BA-CA) were higher in group 1 (P<0.05). After $1.06{\pm}0.93$ year of treatment, $\Delta$ (BA-CA) decreased and there were significant changes in PAH and $\Delta$ (TH-PAH), especially in group 2 (P<0.05 in group 1, and P<0.001 in group 2). In both groups, IGF-1 and IGFBP-3 were not different before and after treatment, but after treatment, IGF-1 level in group 2 was marginally higher than IGF-1 in group 1 (P<0.1). Conclusion : Compromised predicted adult height in girls with early puberty and advanced bone age was significantly improved with GnRH with/without GH treatment in the short-term period. The addition of GH to GnRHa results in a significant increase in PAH compared to GnRHa alone because GnRHa suppressed growth hormone-IGF-1 axis. For comparison of final adult height, further longitudinal follow-up will be needed.

• Nuclear industry
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• v.16 no.8 s.162
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• pp.53-64
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• 1996

미국의 경우 질병으로 인한 사망자의 절반 정도가 암으로 인한 사망이다. 정산 세포 속에 위치한 암세포만을 선택적으로 손상시키기에는 미흡한 기존의 암치료 방법에 비해, 열중성자와 표적핵을 사용하여 방사선에 민감한 암조직 세포만을 효과적으로 죽일 수 있는 방사선 치료 방법 중의 하나인 BNCT 기술이 새롭게 주목을 끌고 있다. BNCT 기술의 현황과 전망을 알아본다.

• Korean Journal of Head & Neck Oncology
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• v.26 no.2
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• pp.171-177
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• 2010

연구목적 : 비인두암 환자들을 대상으로 방사선치료 시 삼차원입체조형치료기법과 용적세기조절회전치료기법을 비교하고 이하선을 포함한 정상조직 보호에 있어 그 차이점을 알아 보고자 본 연구를 시행하였다. 대상 및 방법 : 비인두암 환자 5명을 대상으로 치료계획용 CT(computed tomography)를 시행 후 삼차원입체조형방사선치료계획 과 용적세기조절회전치료계획을 시행하였다. 이를 바탕으로 얻은 선량분포, conformity index(CI) 그리고 선량체적 히스토그램을 통해 손상위험장기(organ at risk)와 계획용표적체적(planning target volume)을 비교 분석하였다. 결 과 : 분석결과 이하선에 조사되는 평균선량이 용적세기조절회전치료계획에서는 43.9%로 삼차원입체조형치료계획에서의 89.4% 보다 유의하게(p=0.043) 감소하였다. 계획용표적체적 conformity index의 경우 용적세기조절회전치료계획 (CI=1.06)에서 삼차원입체조형치료계획(CI=2.55) 보다 유의하게(p=0.043) 향상된 결과를 보였다. 결 론 : 비인두암 환자에서 용적세기조절회전 치료계획 시 삼차원입체조형치료계획 보다 유의하게 이하선에 평균선량이 줄었고 계획용 표적체적에 대한 conformity도 유의하게 향상되는 결과를 보였다. 본 연구가 적은 수의 환자를 대상으로 하였으나 용적세기조절회전치료기법을 시행 시 구강건조증의 발생을 줄일 수 있을 것으로 기대된다. 향후 더 많은 환자군을 대상으로 한 임상연구가 필요할 것으로 사료된다.

• Clinical and Experimental Pediatrics
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• v.49 no.5
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• pp.552-557
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• 2006

Purpose : The recent results observed in precocious puberty and the hope that interrupting puberty might increase adult height have led to an attempt to use GnRH agonist(GnRHa) in children with premature puberty and a poor growth prognosis. We aimed to analyze the growth promoting effect of GnRHa in girls with early puberty and low predicted adult height(PAH). Methods : Thirty six girls were recruited. They were grouped according to the GnRHa treatment period(group 1>6 mo, n=18; group 2<6 mo, n=18). The following variables were analyzed before and after GnRHa treatment : chronological age(CA), bone age(BA), ${\Delta}age$(CA-BA), height, target height (TH), PAH, serum IGF-1, IGFBP-3. Results : Duration of the GnRHa treatment was $0.89{\pm}0.81yr$($1.37{\pm}0.92yr$ in group 1, and $0.41{\pm}0.08yr$ in group 2). Before treatment, none of the variables were different between the two groups. There were no differences in the following variables the between two groups at the end of treatment : CA, BA, ${\Delta}age$, PAH, serum IGF-1, IGFBP-3. But, growth velocity(GV) and PAH increment during treatment were significantly reduced in group 1. Compared with initial PAH, PAH at the end of treatment was significantly increased($3.7{\pm}3.2cm$). The last serum levels of IGF-1 and IGFBP-3 were lower than those before treatment. Conclusion : Even though last PAH didn't approach TH, short term GnRHa administration in early puberty with low predicted PAH was somewhat effective. But, GnRHa administration suppressed the growth hormone-IGF-1 axis. Therefore, it is recommended that growth hormone(GH) should be used in combination with GnRHa.

• Progress in Medical Physics
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• v.17 no.4
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• pp.207-211
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• 2006

The advent of kV cone-beam computed tomography (CBCT) integrated with a linear accelerator allows for more accurate Image-guided radiotherapy (IGRT). IGRT is the technique that corrects target displacement based on internal body information. To do this, the CBCT Image set is acquired just before the beam is delivered and registered with the simulation CT Image set. In this study, we compare the registration results according to the CBCT's reconstruction quality (either high or medium). A total of 56 CBCT projection data from 6 patients were analyzed. The translation vector differences were within 1 mm in all but 3 cases. For rotation displacement difference, components of all three axes were considered and 3 out of 168 ($56{\times}3$ axes) cases showed more than lo of rotation differences.

• 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.28 no.3
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• pp.166-176
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• 2010

Purpose: To determine the appropriate prostate planning target volume (PTV) margins for 3-dimensitional (3D) conformal radiotherapy (CRT) and intensity-modulated radiation therapy (IMRT) patients treated with an endorectal balloon (ERB) under our institutional treatment condition. Materials and Methods: Patients were treated in the supine position. An ERB was inserted into the rectum with 70 cc air prior to planning a CT scan and then each treatment fraction. Electronic portal images (EPIs) and digital reconstructed radiographs (DRR) of planning CT images were used to evaluate inter-fractional patient's setup and ERB errors. To register both image sets, we developed an in-house program written in visual $C^{++}$. A new method to determine prostate PTV margins with an ERB was developed by using the common method. Results: The mean value of patient setup errors was within 1 mm in all directions. The ERB inter-fractional errors in the superior-inferior (SI) and anterior-posterior (AP) directions were larger than in the left-right (LR) direction. The calculated 1D symmetric PTV margins were 3.0 mm, 8.2 mm, and 8.5 mm for 3D CRT and 4.1 mm, 7.9 mm, and 10.3 mm for IMRT in LR, SI, and AP, respectively according to the new method including ERB random errors. Conclusion: The ERB random error contributes to the deformation of the prostate, which affects the original treatment planning. Thus, a new PTV margin method includes dose blurring effects of ERB. The correction of ERB systematic error is a prerequisite since the new method only accounts for ERB random error.

• Progress in Medical Physics
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• v.26 no.3
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• pp.168-177
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• 2015

For evaluating the treatment planning accurately, the quality assurance for treatment planning is recommended when patients were treated with IMRT which is complex and delicate. To realize this purpose, treatment plan quality assurance software can be used to verify the delivered dose accurately before and after of treatment. The purpose of this study is to evaluate the accuracy of treatment plan quality assurance software for each IMRT plan according to MLC DLG (dosimetric leaf gap). Novalis Tx with a built-in HD120 MLC was used in this study to acquire the MLC dynalog file be imported in MobiusFx. To establish IMRT plan, Eclipse RTP system was used and target and organ structures (multi-target, mock prostate, mock head/neck, C-shape case) were contoured in I'mRT phantom. To verify the difference of dose distribution according to DLG, MLC dynalog files were imported to MobiusFx software and changed the DLG (0.5, 0.7, 1.0, 1.3, 1.6 mm) values in MobiusFx. For evaluation dose, dose distribution was evaluated by using 3D gamma index for the gamma criteria 3% and distance to agreement 3 mm, and the point dose was acquired by using the CC13 ionization chamber in isocenter of I'mRT phantom. In the result for point dose, the mock head/neck and multi-target had difference about 4% and 3% in DLG 0.5 and 0.7 mm respectively, and the other DLGs had difference less than 3%. The gamma index passing-rate of mock head/neck were below 81% for PTV and cord, and multi-target were below 30% for center and superior target in DLGs 0.5, 0.7 mm, however, inferior target of multi-target case and parotid of mock head/neck case had 100.0% passing rate in all DLGs. The point dose of mock prostate showed difference below 3.0% in all DLGs, however, the passing rate of PTV were below 95% in 0.5, 0.7 mm DLGs, and the other DLGs were above 98%. The rectum and bladder had 100.0% passing rate in all DLGs. As the difference of point dose in C-shape were 3~9% except for 1.3 mm DLG, the passing rate of PTV in 1.0 1.3 mm were 96.7, 93.0% respectively. However, passing rate of the other DLGs were below 86% and core was 100.0% passing rate in all DLGs. In this study, we verified that the accuracy of treatment planning QA system can be affected by DLG values. For precise quality assurance for treatment technique using the MLC motion like IMRT and VMAT, we should use appropriate DLG value in linear accelerator and RTP system.

• The Science & Technology
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• s.506
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• pp.14-18
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• 2011