• Title/Summary/Keyword: GTV

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Rock-magnetic Properties of Chimneys from TA25 Seamount in the Tofua Arc, Southwest Pacific (통가 EEZ내 TA25 해저산에서 채취한 열수광체의 암석자기학적 특성 연구)

  • Kim, Wonnyon;Pak, Sang Joon;Lee, Kyeong Yong;Moon, Jai-Woon;Kim, Hyun Sub;Choi, Sun Ki
    • Economic and Environmental Geology
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    • v.46 no.3
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    • pp.207-214
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    • 2013
  • To identify rock-magnetic properties of volcanogenic hydrothermal sulfide deposits, chimneys were obtained from the Tofua Arc in Southwest Pacific, using a remotely operated vehicle (ROV) and Grab with AV cameras (GTVs). Three different types of chimneys used in this study are a high-temperature chimney with venting fluid-temperature of about $200^{\circ}C$ (ROV01), a low-temperature chimney of about $80^{\circ}C$ (GTV01), and an inactive chimney (ROV02). Magnetic properties of ROV01 are dominated by pyrrhotite, except for the outermost that experienced severe oxidation. Concentration and grain-size of ROV01 pyrrhotite are relatively low and fine. For GTV01, both magnetic concentration and grain-size increase from interior to margin. Pyrrhotite, dominant in the core, becomes mixed with hematite in the rim of the chimney due to secondary oxidation. High concentration and large grain-size of magnetic minerals characterize the ROV02. Dominant magnetic phases are pyrrhotite, hematite and goethite. In particular, the outermost rim shows a presence of magnetite produced by magnetotactic bacterial activity. Such distinctive contrast in magnetic concentration, grain-size and mineralogy among three different types of chimney enables the rock-magnetic study to characterize an evolution of hydrothermal deposits.

Evaluation of the Feasibility of Applying Metabolic Target Volume in 4D RT Using PET/CT Image (4D RT에서 PET/CT Image를 이용한 Metabolic Target Volume 적용의 유용성 평가)

  • Kim, Chang-Uk;Chun, Keum-Sung;Huh, Kyung-Hoon;Kim, Yeon-Shil;Jang, Hong-Seok;Jung, Won-Gyun;Xing, Lei;Suh, Tae-Suk
    • Progress in Medical Physics
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    • v.21 no.2
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    • pp.174-182
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    • 2010
  • In this study, we evaluated feasibility of applying MTV (Metabolic Target Volume) to respiratory gated radiotherapy for more accurate treatment using various SUV (Standard Uptake Value) from PET images. We compared VOI (Volume of Interest) images from 50%, 30% and 5% SUV (standard uptake volume) from PET scan of an artificial target with GTV (Gross Tumor Volume) images defined by percentage of respiratory phase from 4D-CT scan for respiratory gated radiotherapy. It is found that the difference of VOI of 30% SUV is reduced noticeably comparing with that of 50% SUV in longitudinal direction with respect to total GTV of 4D-CT image. Difference of VOI of 30% SUV from 4D-PET image defined by respiratory phase from 25% inhalation to 25% exhalation, and GTV from 4D-CT with the same phase is shown below 0.6 cm in maximum. Thus, it is better to use 4D-PET images than conventional PET images for applying MTV to gated RT. From the result that VOI of 5% SUV from 4D-PET agrees well with reference image of 4D-CT in all direction, and the recommendation from department of nuclear medicine that 30% SUV be advised for defining tumor range, it is found that using less than 30%SUV will be more accurate and practical to apply MTV for respiratory gated radiotherapy.

The Analysis of Predictive Factors for the Identification of Patients Who Could Benefit from Respiratory-Gated Radiotherapy in Non-Small Cell Lung Cancer (비소세포성 폐암에서 호흡동기방사선치료 적용 환자군의 선택을 위한 예측인자들의 분석)

  • Jang, Seong-Soon;Park, Ji-Chan
    • Radiation Oncology Journal
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    • v.27 no.4
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    • pp.228-239
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    • 2009
  • Purpose: 4DCT scans performed for radiotherapy were retrospectively analyzed to assess the possible benefits of respiratory gating in non-small cell lung cancer (NSCLC) and established the predictive factors for identifying patients who could benefit from this approach. Materials and Methods: Three treatment planning was performed for 15 patients with stage I~III NSCLC using different planning target volumes (PTVs) as follows: 1) PTVroutine, derived from the addition of conventional uniform margins to gross tumor volume (GTV) of a single bin, 2) PTVall phases (patient-specific PTV), derived from the composite GTV of all 6 bins of the 4DCT, and 3) PTVgating, derived from the composite GTV of 3 consecutive bins at end-exhalation. Results: The reductions in PTV were 43.2% and 9.5%, respectively, for the PTVall phases vs. PTVroutine and PTVgating vs. PTVall phases. Compared to PTVroutine, the use of PTVall phases and PTVgating reduced the mean lung dose (MLD) by 18.1% and 21.6%, and $V_{20}$ by 18.2% and 22.0%, respectively. Significant correlations were seen between certain predictive factors selected from the tumor mobility and volume analysis, such as the 3D mobility vector, the reduction in 3D mobility and PTV with gating, and the ratio of GTV overlap between 2 extreme bins and additional reductions in both MLD and $V_{20}$ with gating. Conclusion: The additional benefits with gating compared to the use of patient-specific PTV were modest; however, there were distinct correlations and differences according to the predictive factors. Therefore, these predictive factors might be useful for identifying patients who could benefit from respiratory-gated radiotherapy.

A Study on a Comparative Analysis of 2D and 3D Planning Using CT Simulator for Transbronchial Brachytherapy (전산화단층모의치료기를 이용한 경기관지 근접치료환자의 치료계획에 관한 고찰)

  • Seo, Dong Rin;Kim, Dae Sup;Back, Geum Mun
    • The Journal of Korean Society for Radiation Therapy
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    • v.25 no.1
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    • pp.69-75
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    • 2013
  • Purpose: Transbronchial brachytherapy used in the two-dimensional treatment planning difficult to identify the location of the tumor in the affected area to determine the process analysis. In this study, we have done a comparative analysis for the patient's treatment planning using a CT simulator. Materials and Methods: The analysis was performed by the patients who visited the hospital to June 2012. The patient carried out CT-image by CT simulator, and we were plan to compare with a two-dimensional and threedimensional treatment planning using a Oncentra Brachy planning system (Nucletron, Netherland). Results: The location of the catheter was confirmed the each time on a treatment planning for fractionated transbronchial brachytherapy. GTV volumes were $3.5cm^3$ and $3.3cm^3$. Also easy to determine the dose distribution of the tumor, the errors of a dose delivery were confirmed dose distribution of the prescibed dose for GTV. In the first treatment was 92% and the second was 88%. Conclusion: In order to compensate for the problem through a two-dimensional treatment planning, it is necessary to be tested process for the accurate identification and analysis of the treatment volume and dose distribution. Quantitatively determine the dose delivery error process that is reflected to the treatment planning is required.

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Effectiveness of the Respiratory Gating System for Stereotectic Radiosurgery of Lung Cancer (Lung Cancer의 Stereotactic Radiosurgery시 Respiratory Gating system의 유용성에 대한 연구)

  • Song Heung Kwon;Kim Min Su;Yang Oh Nam;Park Cheol Su;Kwon Kyung Tae;Kim Jeong Man
    • 대한방사선치료학회:학술대회논문집
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    • 2005.06a
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    • pp.13-17
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    • 2005
  • Introduction : For stereotactic radiosurgery (SRS) of a tumor in the region whose movement due to respiration is significant, like Lung lower lobe, the gated therapy, which delivers radiation dose to the selected respiratory phases when tumor motion is small, was peformed using the Respiratory gating system and its clinical effectiveness was evaluated. Methode and Materials : For two SRS patients with a tumor in Lung lower lobe, a marker block (infrared reflector) was attached on the abdomen. While patient' respiratory cycle was monitored with Real-time Position Management (RPM, Varian, USA), 4D CT was performed (10 phases per a cycle). Phases in which tumor motion did not change rapidly were decided as treatment phases. The treatment volume was contoured on the CT images for selected treatment phases using maximum intensity projection (MIP) method. In order to verify setup reproducibility and positional variation, 4D CT was repeated. Result : Gross tumor volume (GTV) showed maximum movement in superior-inferior direction. For patient $\#$1, motion of GTV was reduced to 2.6 mm in treatment phases ($30\%\~60\%$), while that was 9.4 mm in full phases ($0\%\~90\%$) and for patient $\#$2, it was reduced to 2.3 mm in treatment phases ($30\%\~70\%$), while it was 11.7 mm in full phases ($0\%\~90\%$). When comparing two sets of CT images, setup errors in all the directions were within 3 mm. Conclusion : Since tumor motion was reduced less than 5 mm, the Respiratory gating system for SRS of Lung lower lobe is useful.

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Evaluation of VMAT Dose Accuracy According to Couch Rotation in Stereotactic Radiation Surgery of Metastatic Brain Cancer (전 이성 뇌 암의 정위 방사선수술에서 Couch 회전에 따른 VMAT의 선량 정확성 평가)

  • Na, Gwui Geum;Park, Byoung Suk;Cha, Woo Jung;Park, Yong Chul
    • The Journal of Korean Society for Radiation Therapy
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    • v.33
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    • pp.117-125
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    • 2021
  • Purpose: To purpose of this study is to find the correlation of the Set-up error according to the couch rotation and suggest additional margin setting for the GTV. Target and Method: Each scenario treatment plan was created by making the frequency of non-coplanar beams different among all beams. The set-up error value was measured by using the Exact System and the dose accuracy was evaluated by creating a re-treatment plan. Results: When the couch was rotated by 30°, 45°, 60°, and 90°, the mean of the X-axis values was measured to be 0.29 mm, 0.26 mm, 0.51 mm, and 0.08 mm, respectively. The mean of the Y-axis values was measured to be 0.75 mm, 0.5mm, 0.35 mm, and 0.29 mm, respectively. The mean of the Z-axis values was measured to be 0.5 mm, 0.28 mm, 0.22 mm, and 0.1 mm, respectively. There were dose reductions of 0.1%, 3.1%, 1.9% in D99 for 1-NC VMAT, 2-NC VMAT, and 3-NC VMAT, respectively. Conclusion: When treating with 50% or more of non-coplanar beams among total beams, image verification is required. And it is considered to make the treatment plan by adding a 1.5 mm margin to the GTV.

Evaluation of the Usefulness of Restricted Respiratory Period at the Time of Radiotherapy for Non-Small Cell Lung Cancer Patient (비소세포성 폐암 환자의 방사선 치료 시 제한 호흡 주기의 유용성 평가)

  • Park, So-Yeon;Ahn, Jong-Ho;Suh, Jung-Min;Kim, Yung-Il;Kim, Jin-Man;Choi, Byung-Ki;Pyo, Hong-Ryul;Song, Ki-Won
    • The Journal of Korean Society for Radiation Therapy
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    • v.24 no.2
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    • pp.123-135
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    • 2012
  • Purpose: It is essential to minimize the movement of tumor due to respiratory movement at the time of respiration controlled radiotherapy of non-small cell lung cancer patient. Accordingly, this Study aims to evaluate the usefulness of restricted respiratory period by comparing and analyzing the treatment plans that apply free and restricted respiration period respectively. Materials and Methods: After having conducted training on 9 non-small cell lung cancer patients (tumor n=10) from April to December 2011 by using 'signal monitored-breathing (guided- breathing)' method for the 'free respiratory period' measured on the basis of the regular respiratory period of the patents and 'restricted respiratory period' that was intentionally reduced, total of 10 CT images for each of the respiration phases were acquired by carrying out 4D CT for treatment planning purpose by using RPM and 4-dimensional computed tomography simulator. Visual gross tumor volume (GTV) and internal target volume (ITV) that each of the observer 1 and observer 2 has set were measured and compared on the CT image of each respiratory interval. Moreover, the amplitude of movement of tumor was measured by measuring the center of mass (COM) at the phase of 0% which is the end-inspiration (EI) and at the phase of 50% which is the end-exhalation (EE). In addition, both observers established treatment plan that applied the 2 respiratory periods, and mean dose to normal lung (MDTNL) was compared and analyzed through dose-volume histogram (DVH). Moreover, normal tissue complication probability (NTCP) of the normal lung volume was compared by using dose-volume histogram analysis program (DVH analyzer v.1) and statistical analysis was performed in order to carry out quantitative evaluation of the measured data. Results: As the result of the analysis of the treatment plan that applied the 'restricted respiratory period' of the observer 1 and observer 2, there was reduction rate of 38.75% in the 3-dimensional direction movement of the tumor in comparison to the 'free respiratory period' in the case of the observer 1, while there reduction rate was 41.10% in the case of the observer 2. The results of measurement and comparison of the volumes, GTV and ITV, there was reduction rate of $14.96{\pm}9.44%$ for observer 1 and $19.86{\pm}10.62%$ for observer 2 in the case of GTV, while there was reduction rate of $8.91{\pm}5.91%$ for observer 1 and $15.52{\pm}9.01%$ for observer 2 in the case of ITV. The results of analysis and comparison of MDTNL and NTCP illustrated the reduction rate of MDTNL $3.98{\pm}5.62%$ for observer 1 and $7.62{\pm}10.29%$ for observer 2 in the case of MDTNL, while there was reduction rate of $21.70{\pm}28.27%$ for observer 1 and $37.83{\pm}49.93%$ for observer 2 in the case of NTCP. In addition, the results of analysis of correlation between the resultant values of the 2 observers, while there was significant difference between the observers for the 'free respiratory period', there was no significantly different reduction rates between the observers for 'restricted respiratory period. Conclusion: It was possible to verify the usefulness and appropriateness of 'restricted respiratory period' at the time of respiration controlled radiotherapy on non-small cell lung cancer patient as the treatment plan that applied 'restricted respiratory period' illustrated relative reduction in the evaluation factors in comparison to the 'free respiratory period.

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Analysis on the Calculated Dose in the Lung Radiation Surgery Planning Using TomoTherpay (토모테라피를 이용한 폐종양 방사선수술 계획 시 선량 분석)

  • Song, Ju-Young;Jung, Jae-Uk;Yoon, Mee-Sun;Ahn, Sung-Ja;Chung, Woong-Ki;Nah, Byung-Sik;Nam, Taek-Keun
    • Progress in Medical Physics
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    • v.22 no.4
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    • pp.178-183
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    • 2011
  • The applicability and feasibility of TomoTherapy in the lung radiation surgery was analyzed by comparison of the calculated dose distribution in TomoTherapy planning with the results of conventional IMRS (intensity modulated radiation surgery) using LINAC (linear accelerator). The acquired CT (computed tomograph) images of total 10 patients whose tumors' motion were less than 5 mm were used in the radiation surgery planning and the same prescribed dose and the same dose constraints were used between TomoTherapy and LINAC. The results of TomoTherapy planning fulfilled the dose requirement in GTV (gross tumor volume) and OAR (organ at risk) in the same with the conventional IMRS using LINAC. TomoTherapy was superior in the view point of low dose in the normal lung tissue and conventional LINAC was superior in the dose homogeneity in GTV. The calculated time for treatment beam delivery was long more than two times in TomoTherapy compared with the conventional LINAC. Based on the results in this study, TomoTherapy can be evaluated as an effective way of lung radiation surgery for the patients whose tumor motion is little when the optimal planning is produced considering patient's condition and suitability of dose distribution.

Evaluation 4D-CT Simulation used of Motion Organ and Tumor for Respiratory Gated Radiation Therapy (호흡동조방사선치료를 위한 4D-CT simulation을 이용한 동적장기와 종양 움직임 평가)

  • Kim, Seung-Chul;Kim, Min-A
    • The Journal of the Korea Contents Association
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    • v.15 no.9
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    • pp.395-402
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    • 2015
  • when the radiation therapy of chest and abdomen, evaluation of the tumor motion and the data was used to minimize damage to normal tissues by separating the tumor and normal tissue and maximize tumor therapeutic effect. Lung and liver cancer each 20 patients based on the 50% top phase using 4D-CT simulation and Light speed-16 of shooting equipment 30 ~ 70 % gating phase interval and 0 ~90 % movement in the full phase interval was measured. If the full phase 0 ~ 90% with gating phase 30~70% of tumors in the liver and lung is shown the biggest difference compared to the motion and the size of the GTV was the largest difference in the I(inferior), full phase 0~90% degree of tumor motion only when a relatively large, gating phase to 30~70% of the tumor when the movement has been found that the reduced average 7.1mm. In the 4D-CT simulation comparing the motion value when the full phase 0~90 % and gating phase 30~70 % when the motion value, twice in the gating phase 30~70 % more than full phase 0~90 % showed a small movement value. The exposure to normal tissues, based on the results obtained from the 4D-CT simulation can be significantly alleviated, After treatment will reduce pain and disability in patients with radiation is expected to be able to effective treatment.

Predictive factors of symptomatic radiation pneumonitis in primary and metastatic lung tumors treated with stereotactic ablative body radiotherapy

  • Kim, Kangpyo;Lee, Jeongshim;Cho, Yeona;Chung, Seung Yeun;Lee, Jason Joon Bock;Lee, Chang Geol;Cho, Jaeho
    • Radiation Oncology Journal
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    • v.35 no.2
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    • pp.163-171
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    • 2017
  • Purpose: Although stereotactic ablative body radiotherapy (SABR) is widely used therapeutic technique, predictive factors of radiation pneumonitis (RP) after SABR remain undefined. We aimed to investigate the predictive factors affecting RP in patients with primary or metastatic lung tumors who received SABR. Materials and Methods: From 2012 to 2015, we reviewed 59 patients with 72 primary or metastatic lung tumors treated with SABR, and performed analyses of clinical and dosimetric variables related to symptomatic RP. SABR was delivered as 45-60 Gy in 3-4 fractions, which were over 100 Gy in BED when the ${\alpha}/{\beta}$ value was assumed to be 10. Tumor volume and other various dose volume factors were analyzed using median value as a cutoff value. RP was graded per the Common Terminology Criteria for Adverse Events v4.03. Results: At the median follow-up period of 11 months, symptomatic RP was observed in 13 lesions (12 patients, 18.1%), including grade 2 RP in 11 lesions and grade 3 in 2 lesions. Patients with planning target volume (PTV) of ${\leq}14.35mL$ had significantly lower rates of symptomatic RP when compared to others (8.6% vs. 27%; p = 0.048). Rates of symptomatic RP in patients with internal gross tumor volume (iGTV) >4.21 mL were higher than with ${\leq}4.21mL$ (29.7% vs. 6.1%; p = 0.017). Conclusions: The incidence of symptomatic RP following treatment with SABR was acceptable with grade 2 RP being observed in most patients. iGTV over 4.21 mL and PTV of over 14.35 mL were significant predictive factors related to symptomatic RP.