• Radiation Oncology Journal
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• v.11 no.2
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• pp.241-247
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• 1993

Between July 1988 and December 1992, we treated 45 patients who had deep seated inoperable or residual and/or recurrent intracranial tumors using LINAC based stereotactic radiosurgery at the Department of Therapeutic Radiology, Kangnam St. Mary's Hospital, Catholic University Medical College. Treated intracranial tumors included pituitary tumors (n=15), acoustic neurinomas (n=8), meningiomas (n=7), gliomas (n=6), craniopharyngiomas (n=4), pinealomas (n=3), hemangioblastomas (n=2), and solitary metastatic tumor from lung cancer (n=1). The dimension of treatment field varied from 0.23 to 42.88 $cm^3\;(mean;\;7.26\;cm^3)$. The maximum tumor doses ranging from 5 to 35.5 Gy (mean; 29.9 Gy) were given, and depended on patients' age, target volume, location of lesion and previous history of irradiation. There were 22 male and 23 female patients. The age was varied from 5 to 74 years of age (a median age; 43 years). The mean duration of follow-up was 35 months (2~55 months). To date, 18 $(39.1\%)$ of 46 intracranial tumors treated with SRS showed absent or decrease of the tumor by serial follow-up CT and/or MRI and 16 $(34.8\%)$ were stationary, e.g. growth arrest. From the view point of the clinical aspects, 34 $(73.9\%)$ of 46 tumors were considered improved status, that is, alive with no evidence of active tumor and 8 $(17.4\%)$ of them were stable, alive with disease but no deterioration as compared with before SRS. Although there showed slight increase of the tumor in size according to follow-up imagings of 4 cases (pituitary tumor 1, acoustic neurinomas 2, pinealoma 1), they still represented clinically stable status. Clinically, two $(4.4\%)$ Patients who were anaplastic astrocytoma (n=1) and metastatic brain tumor (n=1) were worsened following SRS treatment. So far, no serious complications were found after treatment. The minor degree headache which could be relieved by steroid or analgesics and transient focal hair loss were observed in a few cases. There should be meticulous long term follow-up inall cases.

• The Journal of Korean Society for Radiation Therapy
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• v.16 no.2
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• pp.43-61
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• 2004

Purpose : For qualify improvement in radiotherapy, it is important to set up and evaluate equipment (linac) accurately. In addition, technicians are needed to be fully aware of the equipment's detailed quality and its manual. Therefore, the result of ATP is evaluated and introduced, in order that the technicians are skilled by participating in quality assurance (QA) and understanding the quality of the equipment before clinical use. Method and Material : QA for LINAC 21EX (Varian, US) was done with suppliers its procedure was divided into radiation survey, mechanical test, radiation isocenter test, bean performance, dosimetry, and enhanced dynamic wedge and using X-omat film (Kodak), multidata, densitometer, and electrometer. QA of MLC (Millennium, 120 leaf) attached to LINAC and EPID (Portal vision) were done separately. Result : The leakage dose by survey meter was below the tolerance. In mechanical test, collimater, gantry, and couch rotation were less than 1mm, and the angles were ${\pm}0.1^{\circ}$ for digital and ${\pm}0.5^{\circ}$ for mechanical. The alignment test of the light field and crosshair were evaluated less than 1mm. The (a)symmetrical jaw field was less than ${\pm}0.5mm$. The radiation isocenter test using X-mat film was less than 1mm. The consistency of light field and radiation field was less than ${\pm}0.1mm$. PDD for photon energy was less than ${\pm}1\%$ and for electron energy of $90\%,\;80\%,\;50\%,\;and\;30\%$ were evaluated within the tolerance. Flatness for photon and electron energy was evaluated $2.3\%$ (tolerance $3\%$) and $3\%$ (tolerance $4.5\%$), respectively, and symmetry was $0.45\%$ (tolerance $2\%$) and $0.3\%$ (tolerance $2\%$), respectively. Dosimetry test for short term, MU setting, rep rate, and dose rate accuracy of photon and electron energy was within the tolerance depending on energy, MU, and gantry angle. Conclusion : Accuracy and safety for clinical use of Clinac 21EX was verified through customer acceptance procedure and the quality of the equipment was found out. These can reduce the difficulties in using the equipment. Furthermore, it is useful for clinically treatment of patients by technicians' active participations.

• Journal of the Korean Vacuum Society
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• v.5 no.4
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• pp.269-277
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• 1996

The vacuum systems of PLS linac provides average pressure of $2.6\times 10^{-6}$Pa under high power microwave of 54 MW peak with 4.1 $\mu \textrm s$ pulse width and 10 Hz repetition rates. The base pressure of system is$2.4\times 10^{-6}$Pa with 45$^{\circ}C$ cooling water. The outgassing rate of the system is decreased from $3.0\times 10^{-11}Torr-l/sec-\textrm{cm}^2$ at the initial stage after installation to $1\times 10^{-12}Torr-l/sec-\textrm{cm}^2$ at present. Total accumulated microwave energy dose is about 140 GJ per module. All ion pumps are working under saturated regime and effective pumping speeds of 60 I/s, 230 I/s ion pumps are 45 I/s, 65 I/s, 140 I/s under the operating range. Main problems occurred in recent year are troubles of ion pump controller and vacuum gauge controller, vacuum leak of energy doubler window and electron gun ceramic, and water leak in the dummy load of acceleraing columns. Total of 41 troubles with 140. 8 hours down time give good system availability of 98%. Down time can be reduced by high power waveguide valves and water dummy loads under development, and then availability is expected to be increased up to 99.5%.

• Journal of radiological science and technology
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• v.31 no.3
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• pp.293-298
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• 2008

This study is aimed to investigate the change of serum compositions of mice caused by the irradiation. The 3Gy radiation with 10MeV Linac was once irradiated to whole body of mice and their serum was collected to conduct 14 biochemical analyses. With the collected data, t-test was performed. As the result, the significant change was confirmed in the following 3 compositions. First, the glucose level of the normal control group was $185.43{\pm}14.93$, but the irradiation group was found to be $220.00{\pm}17.58$, which shows significant difference(p<0.001). Second, the BUN(blood urea nitrogen) measurement showed lower value($15.70{\pm}1.48$) in the irradiation group than the normal control group($19.61{\pm}1.65$), which indicates the significant difference in mean value (p<0.01). Third, the measurement of albumin resulted in lower value of $2.89{\pm}0.25$ in irradiation group than $3.19{\pm}0.34$ of the normal control group, which shows the significant difference in mean value(p<0.05). In consequence, the serum of the mice irradiated with 3Gy radiation caused significant change in 3 compositions; glucose, Blood urea nitrogen(BUN) and albumin.

• Journal of the Korean Society of Radiology
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• v.11 no.2
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• pp.157-165
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• 2017

The active transport characteristics of $K^+$ and $Na^+$ pumping system of cell membrane model which irradiated by high energy x-ray(linac 6MeV) was investigated. The cell membrane model used in this experiment was a $Na^+$ type sulfonated copolymerized membrane of styrene and divinylbenezene. The initial flux of the ion was increased with increase of both $H^+$ ion concentration. In this experiment range(pH 1.5-5, temperature $36.5^{\circ}C$), the initial flux of $K^+$ which was not irradiated by radiation was found to be from $2.09{\times}10^{-4}$ to $1.32{\times}10^{-3}mole/cm^2{\cdot}h$ and that of $Na^+$ from $7.09{\times}10^{-4}$ to $1.09{\times}10^{-3}mole/cm^2{\cdot}h$. the initial flux of $K^+$ which was irradiated by radiation was found to be from $21.0{\times}10^{-4}$ to $16.7{\times}10^{-3}mole/cm^2{\cdot}h$ and that of $Na^+$ from $62.0{\times}10^{-4}$ to $20.6{\times}10^{-3}mole/cm^2{\cdot}h$. The ratio $K^+$/$Na^+$ of membrane was about 1.10. And the driving force of pH of irradiated membrane was significantly increased about 9-20 times than membrane which was not irradiated. As active transport of $K^+$ and $Na^+$ of cell membrane model were abnormal, cell damages were appeared at cell.

• Journal of the Korean Society of Radiology
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• v.11 no.2
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• pp.123-130
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• 2017

Patients diagnosed with the serious disease of cancer may have anxiety and fear of closed spaces while receiving radiation therapy. This study investigated patients receiving treatment based on Linac and Tomotherapy to look into this anxiety and fear. Study method was survey. The survey was performed according to treatment duration (treatment within 5 minutes, 10 minutes, over 20 minutes, and over 30 minutes). The patients were also surveyed about any experience of changing treatment rooms or machines due to machine failure. A total of 200 survey questionnaires with full answers were researched in this study. As a result, it was found that the less the patients' experience on radiation therapy, the higher their anxiety was. The dominating reason for this result was because the patients expected possible pain during the treatment process. In terms of treatment machine, Linac showed the highest anxiety of all for the openness of its patient stand. The most stable status was found in the case of treatment between 20 minutes and 30 minutes using Tomotherapy. The reason was the coziness of Tomotherapy machine. In the case of receiving the treatment for over 30 minutes, patients felt anxious for the isolation from the outside. The study findings are expected to serve as the necessary data for quality medical service with enhanced patient satisfaction in the clinical field.

• Progress in Medical Physics
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• v.27 no.4
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• pp.220-223
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• 2016

Generally, it is recommended that the dosimetric effect of carbon fiber couch should be considered especially for an intensity-modulated therapy with a large portion of monitor units from posterior angles. Even a flattening filter free (FFF) beam has been used for stereotactic body radiation therapy (SBRT), the effect of carbon fiber couch for FFF beam is not well known. This work is an effort to evaluate the dosimetric effect of carbon fiber couch for flattened and FFF beam of Elekta linac empirically. The absorbed doses were measured with Farmer type chamber and water-equivalent phantoms with and without couch. And differences of the absorbed doses between with and without couch defined as "couch effect". By comparing calculated dose in treatment planning system (TPS) with measured dose, the optimal density of couch was evaluated. Finally, differences on patient's skin dose and target dose by couch were evaluated in TPS. As a result, the couch effect for 6 and 10 MV flattened beam were -2.71% and -2.32%, respectively. These values were agreed with provided data by vendor within 0.5%. The couch effect for 6 and 10 MV FFF beam were -3.75% and -2.80%, respectively. The patient's skin dose was increased as 18.6% and target dose was decreased as 0.87%, respectively. It was realized that the couch effect of FFF beam was more severe than that of flattened beam. Patient's skin dose and target dose were changed by the couch effect.

• Progress in Medical Physics
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• v.12 no.1
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• pp.95-102
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• 2001

The intracavitary cones were designed which were made of stainless steel and have scratched inside cone to be generated electron scatter and designed to be attached easily to the LINAC collimator and controlled cones length to be contacted smoothly between the patient and the cone tip. Two types of intracavitary cones were designed. One is the straight end cones with circular opening on the distal end and the other is 30 degree beveled end cones with elliptical opening on the distal end. Each type of intracavitary cone ranged in daimeter from 2.5 cm to 3.5 cm and required a separate set of lower trimmer annulias cone diameter. The film phantom was designed with an internal cassette that accurately aligned the film edge with the film phantom surface. Film optical density data were measured by photodensitometer(Wellhofer 700i) Dosimetry measurements were made to commission the LINAC for 6 - 20 MeV electron using the intracavitary cones. Isodose curves were measured for all energy and cones combinations. Output is defined as the maximum dose per MU along the clinical central axis in water at 113 cm SSD. Calibration output, defined to be the output for the 15cm$\times$15cm diameter straight cone, was adjusted to 1.00 cGy/MU at each energy according to the TG-21 protocol.

• Journal of the Korean Society of Radiology
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• v.14 no.2
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• pp.97-104
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• 2020

This aimed at figuring out if there were the radioprotection effects of aronia on livers of laboratory rats radiated through serum test. For the objects of animal testing, one group consists of five male laboratory rats (weight 200~250 g), and the groups were set as follows: Group 1, normal; Group 2, 5 Gy radiated control group; and Group 3, 5 Gy radiated experiment group with aronia. Group 1(A) was prescribed with ordinary meal without radiation while the control group, Group 2(B) was prescribed with ordinary meal and radiation, and the experiment group, Group 3(C) was orally prescribed with aronia (daily oral dosage: 100 mg/kg/day) diluted with distilled water at the amount of 50 mg/kg/day twice a week, using oral zonde needle for rats for 14 days before being radiated, and then, radiation were made on them. For the study, using Linac (Linear Accelerator) 6 MV X-ray therapy device, rats were irradiated on their whole bodies once, and their blood was sampled for conducting five blood serum tests with regard to liver. For statistical analysis, ANOVA test was conducted. In conclusion, as a result of the analysis, it seemed that there were no the radioprotection effects of aronia on liver. However, it was confirmed statistically that ALB (P>0.05) showed no significance and that TP (P<0.05) showed significant differences. It is expected that there should be more tests in future.

• Progress in Medical Physics
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• v.13 no.4
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• pp.181-186
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• 2002

The IMRT planning depends on the algorithm of each planning system and MLC performance of each Linac system. Yonsei Cancer Center introduced an IMRT System at the beginning of February, 2002. The system consists of CORVUS (Nomos, U.S.A.) treatment planning system, LANTIS, PRIMEVIEW and PRIMART (Siemens, U.S.A) linac system. The optimization of CORVUS planning system with PRIMART is an important task to make a desirable quality treatment plan. Our Step ＆ Shoot IMRT system uses Finite Size Pencil Beams (FSPB) dose model, simulated annealing optimization algorithm and IMFAST segmentation algorithm. We constructed treatment plans for four different patient cases with two basic beamlet sizes, 1.0$\times$1.0 $\textrm{cm}^2$ and 0.5$\times$1.0 $\textrm{cm}^2$, and four intensity steps, 5%, 10%, 20%, 33%. Each case's plan was evaluated with the dose volume histograms of target volumes and delivery efficiencies. The patient case of small target volume is sensitive at the change of intensity map's segmentation and it highlighted an effective treatment plan at marrow intensity step and small basic projection beamlet.