PURPOSE: We wanted to improve the setup reproducibility of breast cancer patients when utilizing a commercially available breast board for radiation therapy. The breast board was modified by using a new head rest and 2 types of board fixation devices. MATERIALS AND METHODS: A conventional head/neck rest was modified to be positioned in various slots of the breast board, and it was fabricated 1 cm thinner to provide more comfort to a patient when the patient's neck was rotated. This rest improves the uncertainty of the daily setup. Also, the sagging problems at the left and right sides became negligible with the two types of board fixation devices: (1) the stair type, and (2) the arm type. The first device consists of an upper/lower holder with 4 stair-types of grooves and 4 rectangular inserts. In order to cover the whole range of vertical setup of the breast board, 4 rectangular inserts were needed, and each covered 10 steps. The arm-type fixation device was also fabricated and attached to the breast board. It had two aluminum bars that were fixed by utilizing a lock-type of screw. These devises were evaluated with two volunteers in order to prove the effectiveness of the improved setup accuracy. RESULTS: The developed cranio-caudal fixation device demonstrated that it could reduce the cranio-caudal error by nearly 55% compared to the old device. As for left-and-right inclination, the stair-type and arm-type fixation devices can reduce the relative inclination by nearly 80% and 90%, respectively, compared to the breast board without the fixation device. CONCLUSION: It was verified that the developed devices were effective for positioning the patients and for avoiding inclination of the breast board.
Aluminum ; Arm ; Breast Neoplasms ; Breast* ; Head ; Humans ; Neck ; Patient Positioning* ; Uncertainty ; Volunteers

PURPOSE: To confirm the reproducibility of in vivo transmission dosimetry system and the accuracy of the algorithms for the estimation of transmission dose in head and neck radiation therapy patients. MATERIALS AND MEHTODS: From September 5 to 18, 2001, transmission dose measurements were performed when radiotherapy was given to brain or head and neck cancer patients. The data of 35 patients who were treated more than three times and whose central axis of the beam was not blocked were analyzed in this study. To confirm the reproducibility of this system, transmission dose was measured before daily treatment and then repetitively every hour during the treatment time, with a field size of 10x10 cm2 and a delivery of 100 MU. The accuracy of the transmission dose calculation algorithms was confirmed by comparing estimated dose with measured dose. To accurately estimate transmission dose, tissue inhomogeneity correction was done. RESULTS: The measurement variations during a day were within +/-0.5% and the daily variations in the checked period were within +/-1.0%, which were acceptable for system reproducibility. The mean errors between estimated and measured doses were within +/-5.0% in patients treated to the brain, +/-2.5% in head, and +/-5.0% in neck. CONCLUSION: The results of this study confirmed the reproducibility of our system and its usefulness and accuracy for daily treatment. We also found that tissue inhomogeneity correction was necessary for the accurate estimation of transmission dose in patients treated to the head and neck.
Axis, Cervical Vertebra ; Brain ; Brain Neoplasms ; Head and Neck Neoplasms* ; Head* ; Humans ; Neck ; Radiotherapy

PURPOSE: To develop a wireless CCTV system in semi-beam's eye view (BEV) to monitor daily patient setup in radiation therapy. MATERIALS AND METHODS: In order to get patient images in semi-BEV, CCTV cameras are installed in a custom-made acrylic applicator below the treatment head of a linear accelerator. The images from the cameras are transmitted via radio frequency signal (~2.4 GHz and 10 mW RF output). An expected problem with this system is radio frequency interference, which is solved utilizing RF shielding with Cu foils and median filtering software. The images are analyzed by our custom-made software. In the software, three anatomical landmarks in the patient surface are indicated by a user, then automatically the 3 dimensional structures are obtained and registered by utilizing a localization procedure consisting mainly of stereo matching algorithm and Gauss-Newton optimization. This algorithm is applied to phantom images to investigate the setup accuracy. Respiratory gating system is also researched with real-time image processing. A line-laser marker projected on a patient's surface is extracted by binary image processing and the breath pattern is calculated and displayed in real-time. RESULTS: More than 80% of the camera noises from the linear accelerator are eliminated by wrapping the camera with copper foils. The accuracy of the localization procedure is found to be on the order of 1.5+/-0.7 mm with a point phantom and sub-millimeters and degrees with a custom-made head/neck phantom. With line-laser marker, real-time respiratory monitoring is possible in the delay time of ~0.17 sec. CONCLUSION: The wireless CCTV camera system is the novel tool which can monitor daily patient setups. The feasibility of respiratory gating system with the wireless CCTV is hopeful.
Copper ; Head ; Hope ; Humans ; Noise ; Particle Accelerators

PURPOSE: To evaluate biological characteristics of neutron beam generated by MC50 cyclotron located in the Korea Institute of Radiological and Medical Sciences (KIRAMS). MATERIALS AND METHODS: The neutron beams generated with 15 mm Beryllium target hit by 35 MeV proton beam was used and dosimetry data was measured before in-vitro study. We irradiated 0, 1, 2, 3, 4 and 5 Gy of neutron beam to EMT-6 cell line and surviving fraction (SF) was measured. The SF curve was also examined at the same dose when applying lead shielding to avoid gamma ray component. In the X-ray experiment, SF curve was obtained after irradiation of 0, 2, 5, 10, and 15 Gy. RESULTS: The neutron beams have 84% of neutron and 16% of gamma component at the depth of 2 cm with the field size of 26 x 26 cm2, beam current 20 micro A, and dose rate of 9.25 cGy/min. The SF curve from X-ray, when fitted to linear-quadratic (LQ) model, had 0.611 as alpha/beta ratio (alpha=0.0204, beta=0.0334, R2=0.999, respectively). The SF curve from neutron beam had shoulders at low dose area and fitted well to LQ model with the value of R2 exceeding 0.99 in all experiments. The mean value of alpha and beta were -0.315 (range, -0.254 ~ -0.360) and 0.247 (0.220~0.262), respectively. The addition of lead shielding resulted in no straightening of SF curve and shoulders in low dose area still existed. The RBE of neutron beam was in range of 2.07~2.19 with SF=0.1 and 2.21~2.35 with SF=0.01, respectively. CONCLUSION: The neutron beam from MC50 cyclotron has significant amount of gamma component and this may have contributed to form the shoulder of survival curve. The RBE of neutron beam generated by MC50 was about 2.2.
Beryllium ; Cell Line ; Cyclotrons* ; Gamma Rays ; Korea ; Neutrons* ; Population Characteristics* ; Protons ; Shoulder

PURPOSE: Measurement of transmission dose is useful for in vivo dosimetry. In this study, the algorithm for estimating the transmission dose for open radiation fields was modified for application to partially blocked radiation fields. MATERIALS AND METHODS: The beam data was measured with a flat solid phantom with various blocked fields. A new correction algorithm for partially blocked radiation field was developed from the measured data. This algorithm was tested in some settings simulating clinical treatment with an irregular field shape. RESULTS: The correction algorithm for the beam block could accurately reflect the effect of the beam block, with an error within +/-1.0%, with both square fields and irregularly shaped fields. CONCLUSION: This algorithm can accurately estimate the transmission dose in most radiation treatment settings, including irregularly shaped field.

PURPOSE: Measurement of transmission dose is useful for in vivo dosimetry. In this study, previous algorithm for estimation of transmission dose was modified for use in cases with tissue deficit. MATERIALS AND METHODS: The beam data was measured with flat solid phantom in various conditions of tissue deficit. New algorithm for correction of transmission dose for tissue deficit was developed by physical reasoning. The algorithm was tested in experimental settings with irregular contours mimicking breast cancer patients using multiple sheets of solid phantoms. RESULTS: The correction algorithm for tissue deficit could accurately reflect the effect of tissue deficit with errors within +-1.0% in most situations and within +-3.0% in experimental settings with irregular contours mimicking breast cancer treatment set-up. CONCLUSION: Developed algorithm could accurately reflect the effect of tissue deficit and irregularly shaped body contour on transmission dosimetry.
Breast Neoplasms ; Humans

To know the infection status of zoonotic trematode metacercariae in brackish water fish, we surveyed mullets collected from 18 coastal areas in the Republic of Korea. The metacercariae of Pygidiopsis summa were detected in 236 (68.2%) out of 346 mullets examined. They were found in mullets from 15 areas except for those from Boseong-gun (Jeollanam-do), Pohang-si, and Uljin-gun (Gyeongsangbuk-do). Especially in mullets from Taean-gun (Chungcheongnam-do) and Geoje-si (Gyeongsangnam-do), their prevalences were 100% and 95.5%, and the average metacercarial density was more than 1,000 per fish. They were also detected in mullets from 3 coastal lakes, Gyeongpoho, Songjiho, and Hwajinpoho, in Gangwon-do, and their average densities were 419, 147, and 672 per infected fish, respectively. The metacercariae of 5 other heterophyid species, including Heterophyes nocens, Heterophyopsis continua, Metagonimus sp., Stictodora fuscata, and Stictodora lari, were found in the mullets examined. The metacercariae of H. nocens were detected in 66.7, 100, 28.6, 81.6, 3.9, 61.5, and 27.3% of mullets from Muan-gun, Shinan-gun, Haenam-gun, Gangjin-gun, and Boseong-gun (Jeollanam-do), Hadong-gun, and Geoje-si (Gyeongsangnam-do), and their metacercarial intensities were 64, 84, 119, 99, 1, 24, and 24 per fish infected, respectively. From the above results, it has been confirmed that P. summa metacercariae are heavily infected in mullets from coastal areas of Korea. It is suggested that residents who frequently consume raw mullet dish can be easily infected with heterophyid flukes.
Gangwon-do ; Heterophyidae ; Korea ; Lakes ; Metacercariae ; Prevalence ; Republic of Korea* ; Saline Waters ; Smegmamorpha* ; Trematoda