• The Journal of Korean Society for Radiation Therapy
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• v.25 no.1
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• pp.49-55
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• 2013

Purpose: Respiratory Gated Radiation Therapy (RGRT) has been carried out using RPM (Real-time Position Management) Respiratory Gating System (version 1.7.5, varian, USA) in Asan Medical Center. This study was to analyze and evaluate the accuracy of Respiratory Gated Radiation Therapy (RGRT) according to variation of respiration. Materials and Methods: Making variation of respiration using Motion Phantom:QUASAR Programmable Respiratory Motion Phantom (Moudus Medical Device Inc. CANADA) able to adjust respiration pattern randomly was varying period, amplitude and baseline by analyze 50 patient's respiration of lung and liver cancer. One of the variations of respiration is baseline shift gradually downward per 0.01 cm, 0.03 cm, 0.05 cm. The other variation of respiration is baseline shift accidently downward per 0.2 cm, 0.4 cm, 0.6 cm, 0.8 cm. Experiments were performed in the same way that is used RPM Respiratory Gating System (phase gating, usually 30~70% gating) in Asan Medical Center. Results: It was all exposed radiation under one of the conditions of baseline shift gradually downward per 0.01 cm, 0.03 cm, 0.05 cm. Under the other condition of baseline shift accidently downward per 0.2 cm, 0.4 cm, 0.6 cm, 0.8 cm equally radiation was exposed. Conclusion: The variations of baseline shifts didn't accurately reflect on phase gating in RPM Respiratory Gating System. This inexactitude makes serious uncertainty in Respiratory Gated Radiation Therapy. So, Must be stabilized breathing of patient before conducting Respiratory Gated Radiation Therapy. also must be monitored breathing of patient in the middle of treatment. If you observe considerable changes of breathing when conducting Respiratory Gated Radiation Therapy. Stopping treatment immediately and then must be need to recheck treatment site using fluoroscopy. If patient's respiration rechecked using fluoroscopy restabilize, it is possible to restart Respiratory Gated Radiation Therapy.

• 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.

• Journal of Radiation Protection and Research
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• v.35 no.2
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• pp.63-68
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• 2010

The ultimate goal of radiation treatment is to use enough radiation dosage in order to examine a tumor while protecting normal tissue. Respiratory guided radiotherapy is being clinically implemented to examine a given stabilized area in order to compensate for the problems of patient breathing. This study investigates the effects of breathing movements on 40 patients with liver cancer through the actual radiation therapy plan using 4D-CT and respiratory guided radiotherapy using RPM. Using a commercial RPM respiratory gating system 4D-CT, we acquired 4D CT on multislice helical CT scanners that use different approaches to 4D CT image reconstruction. The results from analyzing forty patients according to age and direction showed no relationship between gender and transition change. The mean left-right, anteroposterior, and craniocaudal total movements were $3.19{\pm}1.29$, $5.44{\pm}2.07$, and $12.54{\pm}4.70$ mm, respectively. Changes were the largest with CC directions and as patients advanced in age, movements were larger. Therefore, as changes occur in treatment areas because of movements caused from breathing, respiratory gating system is put into operation to revise movement and can increase the radiotherapeutics effects in treating liver cancer.

• The Journal of Korean Society for Radiation Therapy
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• v.27 no.1
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• pp.23-30
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• 2015

Purpose : External markers respiratory movement measuring device (RPM; Real-time Position Management, Varian Medical System, USA) Liver Cancer Radiation Therapy Respiratory gated with respiratory signal with irradiation time and the actual research by analyzing the respiratory phase with the breathing motion measurement device respiratory tuning evaluate the accuracy of radiation therapy Materials and Methods : May-September 2014 Novalis Tx. (Varian Medical System, USA) and liver cancer radiotherapy using respiratory gated RPM (Duty Cycle 20%, Gating window 40% ~ 60%) of 16 patients who underwent total when recording the analyzed respiratory movement. After the breathing motion of the external markers recorded on the RPM was reconstructed by breathing through the acts phase analysis, for Beam-on Time and Duty Cycle recorded by using the reconstructed phase breathing breathing with RPM gated the prediction accuracy of the radiation treatment analysis and analyzed the correlation between prediction accuracy and Duty Cycle in accordance with the reproducibility of the respiratory movement. Results : Treatment of 16 patients with respiratory cycle during the actual treatment plan was analyzed with an average difference -0.03 seconds (range -0.50 seconds to 0.09 seconds) could not be confirmed statistically significant difference between the two breathing (p = 0.472). The average respiratory period when treatment is 4.02 sec (${\pm}0.71sec$), the average value of the respiratory cycle of the treatment was characterized by a standard deviation 7.43% (range 2.57 to 19.20%). Duty Cycle is that the actual average 16.05% (range 13.78 to 17.41%), average 56.05 got through the acts of the show and then analyzed% (range 39.23 to 75.10%) is planned in respiratory research phase (40% to 60%) in was confirmed. The investigation on the correlation between the ratio Duty Cycle and planned respiratory phase and the standard deviation of the respiratory cycle was analyzed in each -0.156 (p = 0.282) and -0.385 (p = 0.070). Conclusion : This study is to analyze the acts after the breathing motion of the external markers recorded during the actual treatment was confirmed in a reproducible ratios of actual treatment of breathing motion during treatment, and Duty Cycle, planned respiratory gated window. Minimizing an error of the treatment plan using 4DCT and enhance the respiratory training and respiratory signal monitoring for effective treatment it is determined to be necessary.

• The Journal of Korean Society for Radiation Therapy
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• v.17 no.2
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• pp.125-131
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• 2005

Purpose : 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 performed using the Respiratory gating system and its clinical effectiveness was evaluated. Materials and Methods : 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. Results : 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 ($30{\sim}60%$), while that was 9.4 mm in full phases ($0{\sim}90%$) and for patient #2, it was reduced to 2.3 mm in treatment phases ($30{\sim}70%$), while it was 11.7 mm in full phases ($0{\sim}90%$). 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.

• Progress in Medical Physics
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• v.24 no.1
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• pp.61-67
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• 2013

In this study, we developed and evaluated the patient respiration training method which can help to avoid the problems for the limitation of RGRT applicable patient cases. By using the MEMS (micro-electro-mechanical-system) acceleration sensor, we measured movement of motion phantom. We had compared the response of MEMS with commercially introduced real time patient monitoring (RPM) system. We measured the response of the MEMS with 1 dimensional motion phantom movement for 2.5, 3.0, 3.5 second of period and the 2.0, 3.0, 4.0 cm of the amplitudes. The measured period error of the MEMS system was 0.6~6.0% compared with measured period using RPM system. We found that the shape of MEMS signals were similar with RPM system. From this study, we found the possibility of MEMS as patient training system.

• The Journal of Korean Society for Radiation Therapy
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• v.28 no.1
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• pp.17-25
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• 2016

Purpose : The purpose of this study is to evaluate the variability of tumor motion and respiration pattern in lung cancer patients undergoing Stereotactic Body RadioTherapy(SBRT) by using On-Board imager (OBI) system and Real-time Position Management (RPM) System. Materials and Methods : This study population consisted of 60 lung cancer patient treated with stereotactic body radiotherapy (48 Gy / 4 fractions). Of these, 30 were treated with gating (group 1) and 30 without gating(group2): typically the patients whose tumors showed three-dimensional respiratory motion > 10 mm were selected for gating. 4-dimensional Computed Tomography (4DCT). Cone Beam CT (CBCT) and Fluoroscopy images were used to measure the tumor motion. RPM system was used to evaluate the variability of respiration pattern on SBRT for group1. Results : The mean difference of tumor motion among 4DCT, CBCT and Fluoroscopy images in the cranio-caudal direction was 2.3 mm in group 1, 2. The maximum difference was 12.5 mm in the group 1 and 8.5 mm in group 2. The number of treatment fractions that patient's respiration pattern was within Upper-Lower threshold on SBRT in group 2 was 31 fractions. A patient who exhibited the most unstable pattern exceeded 108 times in a fraction Conclusion : Although many patients in group 1 and 2 kept the reproducibility of tumor motion within 5 mm during their treatment, some patients exhibited variability of tumor motion in the CBCT and Fluoroscopy images. It was possible to improve the accuracy of dose delivery in SBRT without gating for lung cancer patient by using RPM system.

• Progress in Medical Physics
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• v.26 no.2
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• pp.87-92
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• 2015

The gated RapidArc may produce a dosimetric error due to the stop-and-go motion of heavy gantry which can misalign the gantry restart position and reduce the accuracy of important factors in RapidArc delivery such as MLC movement and gantry speed. In this study, the effect of stop-and-go motion in gated RapidArc was analyzed with varying gating window time, which determines the total number of stop-and-go motions. Total 10 RapidArc plans for treatment of liver cancer were prepared. The RPM gating system and the moving phantom were used to set up the accurate gating window time. Two different delivery quality assurance (DQA) plans were created for each RapidArc plan. One is the portal dosimetry plan and the other is MapCHECK2 plan. The respiratory cycle was set to 4 sec and DQA plans were delivered with three different gating conditions: no gating, 1-sec gating window, and 2-sec gating window. The error between calculated dose and measured dose was evaluated based on the pass rate calculated using the gamma evaluation method with 3%/3 mm criteria. The average pass rates in the portal dosimetry plans were $98.72{\pm}0.82%$, $94.91{\pm}1.64%$, and $98.23{\pm}0.97%$ for no gating, 1-sec gating, and 2-sec gating, respectively. The average pass rates in MapCHECK2 plans were $97.80{\pm}0.91%$, $95.38{\pm}1.31%$, and $97.50{\pm}0.96%$ for no gating, 1-sec gating, and 2-sec gating, respectively. We verified that the dosimetric accuracy of gated RapidArc increases as gating window time increases and efforts should be made to increase gating window time during the RapidArc treatment process.

• Progress in Medical Physics
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• v.25 no.2
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• pp.72-78
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• 2014

The aim of the study is to test a hypothesis that quasi-breath-hold (QBH) biofeedback improves the residual respiratory motion management in gated 3D thoracic MR imaging, reducing respiratory motion artifacts with insignificant acquisition time alteration. To test the hypothesis five healthy human subjects underwent two gated MR imaging studies based on a T2 weighted SPACE MR pulse sequence using a respiratory navigator of a 3T Siemens MRI: one under free breathing and the other under QBH biofeedback breathing. The QBH biofeedback system utilized the external marker position on the abdomen obtained with an RPM system (Real-time Position Management, Varian) to audio-visually guide a human subject for 2s breath-hold at 90% exhalation position in each respiratory cycle. The improvement in the upper liver breath-hold motion reproducibility within the gating window using the QBH biofeedback system has been assessed for a group of volunteers. We assessed the residual respiratory motion management within the gating window and respiratory motion artifacts in 3D thoracic MRI both with/without QBH biofeedback. In addition, the RMSE (root mean square error) of abdominal displacement has been investigated. The QBH biofeedback reduced the residual upper liver motion within the gating window during MR acquisitions (~6 minutes) compared to that for free breathing, resulting in the reduction of respiratory motion artifacts in lung and liver of gated 3D thoracic MR images. The abdominal motion reduction in the gated window was consistent with the residual motion reduction of the diaphragm with QBH biofeedback. Consequently, average RMSE (root mean square error) of abdominal displacement obtained from the RPM has been also reduced from 2.0 mm of free breathing to 0.7 mm of QBH biofeedback breathing over the entire cycle (67% reduction, p-value=0.02) and from 1.7 mm of free breathing to 0.7 mm of QBH biofeedback breathing in the gated window (58% reduction, p-value=0.14). The average baseline drift obtained using a linear fit was reduced from 5.5 mm/min with free breathing to 0.6 mm/min (89% reduction, p-value=0.017) with QBH biofeedback. The study demonstrated that the QBH biofeedback improved the upper liver breath-hold motion reproducibility during the gated 3D thoracic MR imaging. This system can provide clinically applicable motion management of the internal anatomy for gated medical imaging as well as gated radiotherapy.

• The Korean Journal of Nuclear Medicine Technology
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• v.21 no.1
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• pp.34-38
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• 2017

Purpose During PET/CT examinations, the movements of internal organs caused by respiration are captured in images during multiple breathing cycles, resulting in the increases in tumor size and effects on SUV. Respiratory synchronized systems were used to evaluate tumor sizes and SUV changes. Materials and Methods Biograph mCT 64 was used for the equipment, and RPM and Anzai systems were used for the respiratory synchronized systems. We used point source and micro-phantom for an experimentation. We were performed on 12 patients who had solid tumors discovered at the base of the lung or at the top of the liver from August through September 2016. The PET images of the exhalation-to-breathing state and the CT images of the post-exhalation suspension state were gained to evaluate changes in radioactivity concentration (KBq/mL), SUVmax, cylinder diameter (mm), and tumor diameter (cm) under the conventional Static, RPM, and Anzai methods. Results The result of measuring the radioactivity concentration of the point source was RPM 94% and Anzai 91% against Static, respectively. In the two cylinders of different radioactivity in the micro-phantom, the SUVmax increased to RPM 61% and 78%, and Anzai 58% and 77% against Static, whereas the cylinder diameters decreased by RPM -26% and -28%, and Anzai -28% and -26%, each respectively. Among the patients, the SUVmax increased from a minimum of RPM 8.2% to a maximum of 94.4% against Static, and from a minimum of Anzai 7.6% to a maximum of 68.3%, respectively. As for the tumor diameters, a minimum of RPM -7.6% to a maximum of -28.9% were achieved, while the Anzai fell by a minimum of -9.6% to a maximum of -27.7%, respectively. There was no significant difference discovered in the phantom study between the RPM and Anzai, yet there was a meaningful difference in the patients' tumors (P<0.05). Conclusion The respiratory synchronized systems of RPM and Anzai yielded no significant difference in the phantom study in which the respiration was executed at regular intervals. However, it was discovered that the patients had a meaningful difference for the irregular respiratory cycle and inter-system differences. Still, the respiratory synchronized systems would be useful for the accurate diagnosis and SUV measurement as the tumor decreased in size against the existing Static and the SUV increased.