A Pilot Research for Real-Time Specific Patient Quality Assurance Using the Hybrid Optimized Vmat Phantom (Hovp) in Volume Modulated Arc Therapy / 의학물리

The purpose of this was to investigate the measurement of fluence dose map for the specific patient quality assurance. The measurement of fluence map was performed using 2D matrixx detector. The absorbed dose was measured by a glass detector, Gafchromic film and ion chamber in Hybrid Optimized VMAT Phantom (HOVP). For 2D Matrixx, the results of comparison were average passing rate 85.22%+/-1.7 (RT_Target), 89.96%+/-2.15 (LT_Target) and 95.14%+/-1.18 (G4). The dose difference was 11.72%+/-0.531, -11.47%+/-0.991, 7.81%+/-0.857, -4.14%+/-0.761 at the G1, G2, G3, G4. In HOVP, the results of comparison for film were average passing rate (3%, 3 mm) 93.64%+/-3.87, 90.82%+/-0.99. We were measured an absolute dose in steep gradient area G1, G2, G3, G4 using the glass detector. The difference between the measurement and calculation are 8.3% (G1), -5.4% (G2), 6.1% (G3), 7.2% (G4). The using an Ion-chamber were an average relative dose error -1.02%+/-0.222 (Rt_target), 0.96%+/-0.294 (Lt_target). Though we need a more study using a transmission detector. However, a measurement of real-time fluence map will be predicting a dose for real-time specific patient quality assurance in volume modulated arc therapy.

A Study of Characteristics of MicroLion Liquid Ionization Chamber for 6 MV Photon Beam / 의학물리

Recently PTW developed a MicroLion liquid ionization chamber which is water_equivalent and has a small sensitive volume of 0.002 cm3. The aim of this work is to investigate such dosimetric characteristics as dose linearity, dose rate dependency, spatial resolution, and output factors of the chamber for the external radiotherapy photon beam. The results were compared to those of Semiflex chamber, Pinpoint chamber and Diode chamber with the sensitive volumes of 0.125 cm3, 0.03 cm3 and 0.0025 cm3, respectively and evaluated to be suitable for small fields. This study was performed in the 6MV photon energy from a Varian 2300 C/D linac accelerator and the MP3 water phantom (PTW, Freiburg) was used. Penumbras in the varios field sizes ranged from 0.5x0.5 cm2 to 10x10 cm2 were used to evaluate the spatial resolution. Output factors were measured in the field sizes of 0.5x0.5 to 40x40 cm2. Readings of the chamber was linearly proportional to dose. Dose rate dependency was measured from 100 MU/min to 600 MU/min, showed a maximum difference of 5.0%, and outputs decreased with dose rates. The spatial resolutions determined with comparing profiles for the field sizes of 0.5x0.5 cm2 to 10x10 cm2 agreed between every detector except the Semiflex chamber to within 2%. Outputs of detectors were compared to that of Semiflex chamber and showed good agreements within 2% for every chamber. This study shows that MicroLion chamber characterized by a high signal-to-noise ratio and water equivalence could be suitable for the small field dosimetry.

Verification of X-sight Lung Tracking System in the CyberKnife / 의학물리

To track moving tumor in real time, CyberKnife system imports a technique of the synchrony respiratory tracking system. The fiducial marker which are detectable in X-ray images were demand in CyberKnife Robotic radiosurgery system. It issued as reference markers to locate and track tumor location during patient alignment and treatment delivery. Fiducial marker implantation is an invasive surgical operation that carries a relatively high risk of pneumothorax. Most recently, it was developed a direct lung tumor registration method that does not require the use of fiducials. The purpose of this study is to measure the accuracy of target applying X-sight lung tracking using the Gafchromic film in dynamic moving thorax phantom. The X-sight Lung Tracking quality assurance motion phantom simulates simple respiratory motion of a lung tumor and provides Gafchromic dosimetry film-based test capability at locations inside the phantom corresponding to a typical lung tumor. The total average error for the X-sight Lung Tracking System with a moving target was 0.85+/-0.22 mm. The results were considered reliable and applicable for lung tumor treatment in CyberKnife radiosurgery system. Clinically, breathing patterns of patients may vary during radiation therapy. Therefore, additional studies with a set real patient data are necessary to evaluate the target accuracy for the X-sight Lung Tracking system.

Verification of X-sight Lung Tracking System in the CyberKnife / 의학물리

To track moving tumor in real time, CyberKnife system imports a technique of the synchrony respiratory tracking system. The fiducial marker which are detectable in X-ray images were demand in CyberKnife Robotic radiosurgery system. It issued as reference markers to locate and track tumor location during patient alignment and treatment delivery. Fiducial marker implantation is an invasive surgical operation that carries a relatively high risk of pneumothorax. Most recently, it was developed a direct lung tumor registration method that does not require the use of fiducials. The purpose of this study is to measure the accuracy of target applying X-sight lung tracking using the Gafchromic film in dynamic moving thorax phantom. The X-sight Lung Tracking quality assurance motion phantom simulates simple respiratory motion of a lung tumor and provides Gafchromic dosimetry film-based test capability at locations inside the phantom corresponding to a typical lung tumor. The total average error for the X-sight Lung Tracking System with a moving target was 0.85+/-0.22 mm. The results were considered reliable and applicable for lung tumor treatment in CyberKnife radiosurgery system. Clinically, breathing patterns of patients may vary during radiation therapy. Therefore, additional studies with a set real patient data are necessary to evaluate the target accuracy for the X-sight Lung Tracking system.

Analysis of Dose Distribution on Critical Organs for Radiosurgery with CyberKnife Real-Time Tumor Tracking System / 의학물리

We measured the dose distribution for spinal cord and tumor using Gafchromic film, applying 3D and 4D-Treatment Planning for lung tumor within the phantom. A measured dose distribution was compared with a calculated dose distribution generated from 3D radiation treatment planning and 4D radiation treatment planning system. The agreement of the dose distribution in tumor for 3D and 4D treatment planning was 90.6%, 97.64% using gamma index computed for a distance to agreement of 1 mm and a dose difference of 3%. However, a gamma agreement index of 3% dose difference tolerence of and 2 mm distance to agreement, the accordance of the dose distribution around cord for 3D and 4D radiation treatment planning was 57.13%, 90.4%. There are significant differences between a calculated dose and a measured dose for 3D radiation treatment planning, no significant differences for 4D treatment planning. The results provide the effectiveness of the 4D treatment planning as compared to 3D. We suggest that the 4-dimensional treatment planning should be considered in the case where such equipments as Cyberknife with the real time tracking system are used to treat the tumors in the moving organ.

Analysis of Accuracy of Apparent Activity According to Calibration Method for High Dose Rate Brachytherapy Source / 의학물리

The aim of this study is to introduce the accuracy of Ir-192 source's apparent activity using the well-type chamber and the Farmer-type ionization chamber in the high dose rate brachytherapy. We measured the apparent activity of Ir-192 that each medical center in the country has and the apparent activity of calibration certificate provided by manufacturer is compared with that by our experimental measurement. The number of sources used for the activity comparison was 5. The accuracy of the measured activity was in the range of -2.8% to -1.0% and -2.1% to 0.2% for the Farmer-type chamber system (Jig) and for the well-type, respectively. The maximum difference was within 1.0% for comparison with two calibration's tool. Our results demonstrate that well-type chamber as wall as Farmer-type chamber is a appropriate system as the routine source calibration procedures in HDR brachytherapy. Whenever a new source is installed to use in clinics, by periods, a source calibration should be carried out.

The Effects on Pain Relief of Intraarticular Tramadol and Neostigmine after Knee Arthroscopic Surgery / 대한마취과학회지

BACKGROUND: Evidence has accumulated that tramadol hydrochloride can produce relief of moderate to severe pain across the range of acute and chronic pain states by combining a synergistically weak opioid and a monoaminergically mediated antinociceptive mechanism. Neostigmine can produce antinociceptive effects by interacting with muscarine receptors in peripheral tissues. This study was designed to determine whether intraarticular tramadol results in better analgesic effect and whether tramadol and neostigmine would provide superior analgesia to tramadol alone, after knee arthroscopic surgery. METHODS: Forty-five ASA class 1 or 2 patients undergoing arthroscopic knee surgery were randomly allocated to three treatment groups. All patients received general anesthesia with nitrous oxide, O2 and inhalational agents. When the surgical procedure was completed, the study drug was injected into the patient's knee joint through the arthroscope. Patients in group 1 (n = 15) received 30 ml of 0.5% mepivacaine; patients in group 2 (n = 15) received tramadol 50 mg and 30 ml of 0.5% mepivacaine; patients in group 3 (n = 15) received a combination of tramadol 50 mg, neostigmine 100 micro gram and 30 ml of 0.5% mepivacaine. Postoperative pain was assessed using the visual analogue scale (VAS) at 1, 2, 4, 6, 12 and 24 hours after the intraarticular injection. RESULTS: There were no significant differences among the three groups in the 1 to 2 hour postoperative period and groups 2 and 3 showed significantly lower VAS score than group 1 from 4 to 24 hours postoperatively. CONCLUSIONS: It is concluded that after knee arthroscopy, intraarticular injection of tramadol had a good analgesic effect, whereas neostigmine added to tramadol did not show superior analgesic effects over tramadol alone.

The Effects on Pain Relief of Intraarticular Tramadol and Neostigmine after Knee Arthroscopic Surgery / 대한마취과학회지

BACKGROUND: Evidence has accumulated that tramadol hydrochloride can produce relief of moderate to severe pain across the range of acute and chronic pain states by combining a synergistically weak opioid and a monoaminergically mediated antinociceptive mechanism. Neostigmine can produce antinociceptive effects by interacting with muscarine receptors in peripheral tissues. This study was designed to determine whether intraarticular tramadol results in better analgesic effect and whether tramadol and neostigmine would provide superior analgesia to tramadol alone, after knee arthroscopic surgery. METHODS: Forty-five ASA class 1 or 2 patients undergoing arthroscopic knee surgery were randomly allocated to three treatment groups. All patients received general anesthesia with nitrous oxide, O2 and inhalational agents. When the surgical procedure was completed, the study drug was injected into the patient's knee joint through the arthroscope. Patients in group 1 (n = 15) received 30 ml of 0.5% mepivacaine; patients in group 2 (n = 15) received tramadol 50 mg and 30 ml of 0.5% mepivacaine; patients in group 3 (n = 15) received a combination of tramadol 50 mg, neostigmine 100 micro gram and 30 ml of 0.5% mepivacaine. Postoperative pain was assessed using the visual analogue scale (VAS) at 1, 2, 4, 6, 12 and 24 hours after the intraarticular injection. RESULTS: There were no significant differences among the three groups in the 1 to 2 hour postoperative period and groups 2 and 3 showed significantly lower VAS score than group 1 from 4 to 24 hours postoperatively. CONCLUSIONS: It is concluded that after knee arthroscopy, intraarticular injection of tramadol had a good analgesic effect, whereas neostigmine added to tramadol did not show superior analgesic effects over tramadol alone.

The Effect of Continuous Intravenous Infusion of Esmolol on Heart Rate and Blood Pressure after Ketamine Induction and Endotracheal Intubation / 대한마취과학회지

BACKGROUND: This study was designed to evaluate the effect of continuous intravenous infusion of esmolol on the heart rate and blood pressure, after ketamine induction and endotracheal intubation. METHODS: With informed consent, forty patients with ASA physical status 1 were randomly divided into two groups. Esmolol group received the continuous intravenous infusion of esmolol (at 500 microgram/kg/min for 1 minute as a loading dose and at 300 microgram/kg/min until 7 minutes after endotracheal intubation as a maintenance dose) and saline group received normal saline at the same volume-rate. 2 mg/kg of ketamine and 0.15 mg/kg of vecuronium were given at 4 minutes after the test drugs. Intubation was performed at 3 minutes after the induction. The changes of blood pressure, heart rate and rate pressure product were measured at different time intervals (preinduction, preintubation, immediately after intubation and postintubation 1, 3, 5 and 7minutes). RESULTS: In the esmolol group, the changes of systolic blood pressure, diastolic blood pressure, heart rate and rate pressure product were significantly attenuated when compared with the saline group. The changes in heart rate at preintubation and intubation were not statistically significant when compared with the baseline value within the esmolol group. CONCLUSIONS: It is concluded that the infusion of esmolol attenuated the hemodynamic changes following ketamine induction and endotracheal intubation, but it is still needed to find the dosage of esmolol.