• The Journal of Korean Society for Radiation Therapy
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• v.24 no.2
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• pp.183-188
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• 2012

Purpose: The concern of improving the quality of life and reducing side effects related to cancer treatment has been a subject of interest in recent years with advances in cancer treatment techniques and increasing survival time. This study is an analysis of differing scattered dose to the contralateral breast using common different treatment techniques. Materials and Methods: Eclipse 10.0 (Varian, USA) based $30^{\circ}$ EDW (Enhanced dynamic wedge) plan, $15^{\circ}$ wedge plan, $30^{\circ}$ wedge plan, Open beam plan, FiF (field in field) plan were established using CT image of breast phantom which in our hospital. Each treatment plan were designed to exposure 400 cGy using CL-6EX (VARIAN, USA) and we measured scattered dose at 1 cm, 3 cm, 5 cm, 9 cm away from medial side of the phantom at 1 cm depth using ionization chamber (FC 65G, IBA). We carried out measurement by separating effect of medial tangential field and lateral tangential field and analyze. Results: The evaluation of scattered dose to contralateral breast, $30^{\circ}$ EDW plan, $15^{\circ}$ wedge plan, $30^{\circ}$ wedge plan, Open beam plan, FIF plan showed 6.55%, 4.72%, 2.79%, 2.33%, 1.87% about prescription dose of each treatment plan. The result of scattered dose measurement by separating effect of medial tangential field and lateral tangential field results were 4.94%, 3.33%, 1.55%, 1.17%, 0.77% about prescription dose at medial tangential field and 1.61%, 1.40%, 1.24%, 1.16%, 1.10% at lateral tangential field along with measured distance. Conclusion: In our experiment, FiF treatment technique generates minimum of scattered dose to contralateral breast which come from mainly phantom scatter factor. Whereas $30^{\circ}$ wedge plan generates maximum of scattered doses to contralateral breast and 3.3% of them was scattered from gantry head. The description of treatment planning system showed a loss of precision for a relatively low scatter dose region. Scattered dose out of Treatment radiation field is relatively lower than prescription dose but, in decision of radiation therapy, it cannot be ignored that doses to contralateral breast are related with probability of secondary cancer.

• Progress in Medical Physics
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• v.22 no.2
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• pp.99-105
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• 2011

The purpose of this study is to evaluate the accuracy of IMRT in our clinic from based on TG119 procedure and establish action level. Five IMRT test cases were described in TG119: multi-target, head&neck, prostate, and two C-shapes (easy&hard). There were used and delivered to water-equivalent solid phantom for IMRT. Absolute dose for points in target and OAR was measured by using an ion chamber (CC13, IBA). EBT2 film was utilized to compare the measured two-dimensional dose distribution with the calculated one by treatment planning system. All collected data were analyzed using the TG119 specifications to determine the confidence limit. The mean of relative error (%) between measured and calculated value was $1.2{\pm}1.1%$ and $1.2{\pm}0.7%$ for target and OAR, respectively. The resulting confidence limits were 3.4% and 2.6%. In EBT2 film dosimetry, the average percentage of points passing the gamma criteria (3%/3 mm) was $97.7{\pm}0.8%$. Confidence limit values determined by EBT2 film analysis was 3.9%. This study has focused on IMRT commissioning and quality assurance based on TG119 guideline. It is concluded that action level were ${\pm}4%$ and ${\pm}3%$ for target and OAR and 97% for film measurement, respectively. It is expected that TG119-based procedure can be used as reference to evaluate the accuracy of IMRT for each institution.

• Progress in Medical Physics
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• v.24 no.2
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• pp.85-91
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• 2013

At present, megavoltage computed tomography (MVCT) is the only method used to correct the position of tomotherapy patients. MVCT produces extra radiation, in addition to the radiation used for treatment, and repositioning also takes up much of the total treatment time. To address these issues, we suggest the use of a video image-guided setup (VIGS) system for correcting the position of tomotherapy patients. We developed an in-house program to correct the exact position of patients using two orthogonal images obtained from two video cameras installed at $90^{\circ}$ and fastened inside the tomotherapy gantry. The system is programmed to make automatic registration possible with the use of edge detection of the user-defined region of interest (ROI). A head-and-neck patient is then simulated using a humanoid phantom. After taking the computed tomography (CT) image, tomotherapy planning is performed. To mimic a clinical treatment course, we used an immobilization device to position the phantom on the tomotherapy couch and, using MVCT, corrected its position to match the one captured when the treatment was planned. Video images of the corrected position were used as reference images for the VIGS system. First, the position was repeatedly corrected 10 times using MVCT, and based on the saved reference video image, the patient position was then corrected 10 times using the VIGS method. Thereafter, the results of the two correction methods were compared. The results demonstrated that patient positioning using a video-imaging method ($41.7{\pm}11.2$ seconds) significantly reduces the overall time of the MVCT method ($420{\pm}6$ seconds) (p<0.05). However, there was no meaningful difference in accuracy between the two methods (x=0.11 mm, y=0.27 mm, z=0.58 mm, p>0.05). Because VIGS provides a more accurate result and reduces the required time, compared with the MVCT method, it is expected to manage the overall tomotherapy treatment process more efficiently.

• The Korean Journal of Nuclear Medicine
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• v.36 no.1
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• pp.1-7
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• 2002

Positron Emission Tomography (PET) is a nuclear medicine imaging modality that consists of systemic administration to a subject of a radiopharmaceutical labeled with a positron-emitting radionuclide. Following administration, its distribution in the organ or structure under study can be assessed as a function of time and space by (1) defecting the annihilation radiation resulting from the interaction of the positrons with matter, and (2) reconstructing the distribution of the radioactivity from a series of that used in computed tomography (CT). The nuclides most generally exhibit chemical properties that render them particularly desirable in physiological studies. The radionuclides most widely used in PET are F-18, C-11, O-15 and N-13. Regarding to the number of the current PET Centers worldwide (based on ICP data), more than 300 PET Centers were in operation in 2000. The use of PET technology grew rapidly compared to that in 1992 and 1996, particularly in the USA, which demonstrates a three-fold rise in PET installations. In 2001, 194 PET Centers were operating in the USA. In 1994, two clinical and research-oriented PET Centers at Seoul National University Hospital and Samsung Medical Center, was established as the first dedicated PET and Cyclotron machines in Korea, followed by two more PET facilities at the Korea Cancer Center Hospital, Ajou Medical Center, Yonsei University Medical Center, National Cancer Center and established their PET Center. Catholic Medical School and Pusan National University Hospital have finalized a plan to install PET machine in 2002, which results in total of nine PET Centers in Korea. Considering annual trends of PET application in four major PET centers in Korea in Asan Medical Center recent six years (from 1995 to 2000), a total of 11,564 patients have been studied every year and the number of PET studies has shown steep growth year upon year. We had 1,020 PET patients in 1995. This number increased to 1,196, 1,756, 2,379, 3,015 and 4,414 in 1996,1997,1998,1999 and 2000, respectively. The application in cardiac disorders is minimal, and among various neuropsychiatric diseases, patients with epilepsy or dementia can benefit from PET studios. Recently, we investigated brain mapping and neuroreceptor works. PET is not a key application for evaluation of the cardiac patients in Korea because of the relatively low incidence of cardiac disease and less costly procedures such as SPECT can now be performed. The changes in the application of PET studios indicate that, initially, brain PET occupied almost 60% in 1995, followed by a gradual decrease in brain application. However, overall PET use in the diagnosis and management of patients with cancer was up to 63% in 2000. The current medicare coverage policy in the USA is very important because reimbursement policy is critical for the promotion of PET. In May 1995, the Health Care Financing Administration (HCFA) began covering the PET perfusion study using Rubidium-82, evaluation of a solitary pulmonary nodule and pathologically proven non-small cell lung cancer. As of July 1999, Medicare's coverage policy expanded to include additional indications: evaluation of recurrent colorectal cancer with a rising CEA level, staging of lymphoma and detection of recurrent or metastatic melanoma. In December of 2001, National Coverage decided to expand Medicare reimbursement for broad use in 6 cancers: lung, colorecctal, lymphoma, melanoma, head and neck, and esophageal cancers; for determining revascularization in heart diseases; and for identifying epilepsy patients. In addition, PET coverage is expected to further expand to diseases affecting women, such as breast, ovarian, uterine and vaginal cancers as well as diseases like prostate cancer and Alzheimer's disease.

• Journal of Korean Neurosurgical Society
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• v.46 no.4
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• pp.370-377
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• 2009

Objective : There is no definite adjustment protocol for patients shunted with programmable valves. Therefore, we attempted to find an appropriate method to adjust the valve, initial valve-opening pressure, adjustment scale, adjustment time interval, and final valve-opening pressure of a programmable valve. Methods : Seventy patients with hydrocephalus of various etiologies were shunted with programmable shunting devices (Micro Valve with $RICKHAM^{(R)}$ Reservoir). The most common initial diseases were subarachnoid hemorrhage (SAH) and head trauma. Sixty-six patients had a communicating type of hydrocephalus, and 4 had an obstructive type of hydrocephalus. Fifty-one patients had normal pressure-type hydrocephalus and 19 patients had high pressure-type hydrocephalus. We set the initial valve pressure to $10-30\;mmH_2O$, which is lower than the preoperative lumbar tapping pressure or the intraoperative ventricular tapping pressure, conducted brain computerized tomographic (CT) scans every 2 to 3 weeks, correlated results with clinical symptoms, and reset valve-opening pressures. Results : Initial valve-opening pressures varied from 30 to $180\;mmH_2O$ (mean, $102{\pm}27.5\;mmH_2O$). In high pressure-type hydrocephalus patients, we have set the initial valve-opening pressure from 100 to $180\;mmH_2O$. We decreased the valve-opening pressure $20-30\;mmH_2O$ at every 2- or 3-week interval, until hydrocephalus-related symptoms improved and the size of the ventricle was normalized. There were 154 adjustments in 81 operations (mean, 1.9 times). In 19 high pressure-type patients, final valve-opening pressures were $30-160\;mmH_2O$, and 16 (84%) patients' symptoms had nearly improved completely. However, in 51 normal pressure-type patients, only 31 (61%) had improved. Surprisingly, in 22 of the 31 normal pressure-type improved patients, final valve-opening pressures were $30\;mmH_2O$ (16 patients) and $40\;mmH_2O$ (6 patients). Furthermore, when final valve-opening pressures were adjusted to $30\;mmH_2O$, 14 patients symptom was improved just at the point. There were 18 (22%) major complications : 7 subdural hygroma, 6 shunt obstructions, and 5 shunt infections. Conclusion : In normal pressure-type hydrocephalus, most patients improved when the final valve-opening pressure was $30\;mmH_2O$. We suggest that all normal pressure-type hydrocephalus patients be shunted with programmable valves, and their initial valve-opening pressures set to $10-30\;mmH_2O$ below their preoperative cerebrospinal fluid (CSF) pressures. If final valve-opening pressures are lowered in 20 or $30\;mmH_2O$ scale at 2- or 3-week intervals, reaching a final pressure of $30\;mmH_2O$, we believe that there is a low risk of overdrainage syndromes.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.1
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• pp.19-25
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• 2014

Purpose: Integrated PET/MRI has been developed recently has become a lot of help to the point oncologic, neological, cardiological nuclear medicine. By using this PET/MRI, a ${\mu}-map$ is created some special MRI sequence which may be divided parts of the body for attenuation correction. However, because an MRI contrast agent is necessary in order to obtain an more MRI information, we will evaluate to see an effect of SUV on PET image that corrected attenuation by MRI with contrast agent. Materials and Methods: As PET/MRI machine, Biograph mMR (Siemens, Germany) was used. For phantom test, 1mCi $^{18}F-FDG$ was injected in cylinderical uniformity phantom, and then acquire PET data about 10 minutes with VIBE-DIXON, UTE MRI sequence image for attenuation correction. T1 weighted contrast media, 4 cc DOTAREM (GUERBET, FRANCE) was injected in a same phatnom, and then PET data, MRI data were acquired by same methodes. Using this PET, non-contrast MRI and contrast MRI, it was reconstructed attenuation correction PET image, in which we evanuated the difference of SUVs. Additionally, for let a high desity of contrast media, 500 cc 2 plastic bottles were used. We injected $^{18}F-FDG$ with 5 cc DOTAREM in first bottle. At second bottle, only $^{18}F-FDG$ was injected. and then we evaluated a SUVs reconstructed by same methods. For clinical patient study, rectal caner-pancreas cancer patients were selected. we evaluated SUVs of PET image corrected attenuastion by contrast weighted MRI and non-contrast MRI. Results: For a phantom study, although VIBE DIXON MRI signal with contrast media is 433% higher than non-contrast media MRI, the signals intensity of ${\mu}-map$, attenuation corrected PET are same together. In case of high contrast media density, image distortion is appeared on ${\mu}-map$ and PET images. For clinical a patient study, VIBE DIXON MRI signal on lesion portion is increased in 495% by using DOTAREM. But there are no significant differences at ${\mu}-map$, non AC PET, AC-PET image whether using contrast media or not. In case of whole body PET/MRI study, %diff between contras and non contrast MRAC at lung, liver, renal cortex, femoral head, myocardium, bladder, muscle are -4.32%, -2.48%, -8.05%, -3.14%, 2.30%, 1.53%, 6.49% at each other. Conclusion: In integrated PET/MRI, a segmentation ${\mu}-map$ method is used for correcting attenuation of PET signal. although MRI signal for attenuation correciton change by using contrast media, ${\mu}-map$ will not change, and then MRAC PET signal will not change too. Therefore, MRI contrast media dose not affect for attenuation correction PET. As well, not only When we make a flow of PET/MRI protocol, order of PET and MRI sequence dose not matter, but It's possible to compare PET images before and after contrast agent injection.