• Journal of the Korean Society of Radiology
• /
• v.14 no.5
• /
• pp.627-634
• /
• 2020

Instead of lead, we intend to develop shielding materials for morphological implementation by mixing barium sulfate, an eco-friendly substance, and PLA filament, a 3D printer material. The environmental substance, barium sulfate powder and PLA filament, a 3D printer material, were used, and the shielding was made with a 3D printer after being fused into an extruder to mix the powder powder of barium sulfate with PLA. To check the mixing ratio of barium sulfate powder and PLA filament, the mixing input was analyzed, and the absorption dose by thickness according to barium sulfate content was obtained to check the shielding function of the mixed shielding. In the evaluation of the mixture of sulfate barium powder particles and PLA filaments, it was mixed in the most appropriate proportion when the content was 30% in the apparent and electron microscopic observation photographs. In the absorption dose results by thickness according to barium sulfate content, the difference between the content of 0% and the content of each % was greatest at 0.5 cm in thickness and the lowest dose value at 3 cm in thickness when the barium content was 30%. In addition, as the barium content began to increase at 30%, the absorbed dose value increased again. Instead of conventional lead, barium sulfate, an eco-friendly substance, could be mixed with PLA, a filament material, to create morphological shielding. Based on this study, it is expected that the mixing ratio of barium to the mixture is the most appropriate 30%, and will be used as the basis for the implementation of morphological shielding using 3D printers in the diagnosis and treatment section.

• Journal of radiological science and technology
• /
• v.41 no.3
• /
• pp.201-207
• /
• 2018

The purpose of this study is to evaluate the performance of a "stealth chamber" as a novel reference chamber for measuring percentage depth dose (PDD) and profile of 6, 8 and 10 MV photon energies. The PDD curves and dose profiles with fields ranging from $3{\times}3$ to $25{\times}25cm^2$ were acquired from measurements by using the stealth chamber and CC 13 chamber as reference chamber. All measurements were performed with Varian VitalBeam linear accelerator. In order to assess the performance of stealth chamber, PDD curves and profiles measured with stealth chamber were compared with measurement data using CC13 chamber. For PPDs measured with both chambers, the dosimetric parameters such as $d_{max}$ (depth of maximum dose), $D_{50}$ (PDD at 50 mm depth), and $D_{100}$ (PDD at 100 mm depth) were analyzed. Moreover, root mean square error (RMSE) values for profiles at $d_{max}$ and 100 mm depth were evaluated. The measured PDDs and profiles between the stealth chamber and CC13 chamber as reference detector had almost comparable. For PDDs, the evaluated dosimetric parameters were observed small difference (<1%) for all energies and field sizes, except for $d_{max}$ less than 2 mm. In addition, the difference of RMSEs for profiles at $d_{max}$ and 100 mm depth was similar for both chambers. This study confirmed that the use of stealth chamber for measuring commission beam data is a feasible as reference chamber for fields ranging from $3{\times}3$ to $20{\times}20cm^2$. Furthermore, it has an advantage with respect to measurement of the small fields (less than $3{\times}3cm^2$ field) although not performed in this study.

• Proceedings of the Korean Society of Medical Physics Conference
• /
• 2002.09a
• /
• pp.298-299
• /
• 2002

WERC (Wakasa Wan Energy Research Center) has started the proton cancer therapy since June 2002. We use Hitachi 3D treatment planning (version 1.6) that can calculate the proton dose distribution by use of the pencil beam algorithm as well as the broad beam algorithm practically fast. This treatment planning software satisfies almost functions required in the proton therapy and includes some advanced techniques such as the 3D region glowing function that can search the target region three-dimensionally based on the CT-values. In this paper, we will introduce this planning system and present our evaluation from point of view of both clinical usage and QA.

• Journal of the Korean Society of Radiology
• /
• v.16 no.6
• /
• pp.687-695
• /
• 2022

To find a 3D printer material that can replace lead used as a shield for high-energy electron beam treatment, the shielding composites were simulated by using MCNP6 programs. The Percent Depth Dose (PDD), Flatness, and Symmetry of linear accelerators emitting high-energy electron beams were measured, and the linear accelerator was compared with MCNP6 after simulation, confirming that the source term between the actual measurement and simulation was consistent. By simulating the lead shield, the appropriate thickness of the lead shield capable of shielding 95% or more of the absorbed dose was selected. Based on the absorption dose data for lead shield with a thickness of 3 mm, the shielding performance was analyzed by simulating 1, 5, 10, and 15 mm thicknesses of ABS+W (10%), ABS+Bi (10%), and PLA+Fe (10%). Each prototype was manufactured with a 3D printer, measured and analyzed under the same conditions as in the simulation, and found that when ABS+W (10%) material was formed to have a thickness of at least 10mm, it had a shielding performance that could replace lead with a thickness of 3mm. The surface morphology and atomic composition of the ABS+W (10%) material were evaluated using a scanning electron microscope (SEM) and an energy dispersive X-ray spectrometer (EDS). From these results, it was confirmed that replacing the commercialized lead shield with ABS+W (10%) material not only produces a shielding effect such as lead, but also can be customized to patients using a 3D printer, which can be very useful for high-energy electron beam treatment.

• Journal of radiological science and technology
• /
• v.39 no.3
• /
• pp.391-397
• /
• 2016

Stereotactic body radiotherapy is effective technic in radiotherapy for low stage lung cancer. But lung cancer is affected by respiratory so accurately concentrate high dose to the target is very difficult. In this study, evaluated the target volume according to how to take the image. And evaluated the dose by photoluminescence glass dosimeter according to how to contour the volume and respiratory range. As a result, evaluated the 4D CT volume was 10.4 cm3 which was closest value of real size target. And in dose case is internal target volume dose was 10.82, 16.88, 21.90 Gy when prescribed dose was 10, 15, 20 Gy and it was the highest dose. Respiratory gated radiotherapy dose was more higher than internal target volume. But it made little difference by respiratory range. Therefore, when moving cancer treatment, acquiring image by 4D CT, contouring internal target volume and respiratory gated radiotherapy technic would be the best way.

• The Journal of Korean Society for Radiation Therapy
• /
• v.32
• /
• pp.93-109
• /
• 2020

Purpose: The radiochromic film (Gafchromic EBT3, Ashland Advanced Materials, USA) and 3-dimensional analysis system dosimetry checkTM (DC, MathResolutions, USA) were evaluated for patient-specific quality assurance (QA) of helical tomotherapy. Materials and Methods: Depending on the tumors' positions, three types of targets, which are the abdominal tumor (130.6㎤), retroperitoneal tumor (849.0㎤), and the whole abdominal metastasis tumor (3131.0㎤) applied to the humanoid phantom (Anderson Rando Phantom, USA). We established a total of 12 comparative treatment plans by the four geometric conditions of the beam irradiation, which are the different field widths (FW) of 2.5-cm, 5.0-cm, and pitches of 0.287, 0.43. Ionization measurements (1D) with EBT3 by inserting the cheese phantom (2D) were compared to DC measurements of the 3D dose reconstruction on CT images from beam fluence log information. For the clinical feasibility evaluation of the DC, dose reconstruction has been performed using the same cheese phantom with the EBT3 method. Recalculated dose distributions revealed the dose error information during the actual irradiation on the same CT images quantitatively compared to the treatment plan. The Thread effect, which might appear in the Helical Tomotherapy, was analyzed by ripple amplitude (%). We also performed gamma index analysis (DD: 3mm/ DTA: 3%, pass threshold limit: 95%) for pattern check of the dose distribution. Results: Ripple amplitude measurement resulted in the highest average of 23.1% in the peritoneum tumor. In the radiochromic film analysis, the absolute dose was on average 0.9±0.4%, and gamma index analysis was on average 96.4±2.2% (Passing rate: >95%), which could be limited to the large target sizes such as the whole abdominal metastasis tumor. In the DC analysis with the humanoid phantom for FW of 5.0-cm, the three regions' average was 91.8±6.4% in the 2D and 3D plan. The three planes (axial, coronal, and sagittal) and dose profile could be analyzed with the entire peritoneum tumor and the whole abdominal metastasis target, with planned dose distributions. The dose errors based on the dose-volume histogram in the DC evaluations increased depending on FW and pitch. Conclusion: The DC method could implement a dose error analysis on the 3D patient image data by the measured beam fluence log information only without any dosimetry tools for patient-specific quality assurance. Also, there may be no limit to apply for the tumor location and size; therefore, the DC could be useful in patient-specific QAl during the treatment of Helical Tomotherapy of large and irregular tumors.

• Korean Journal of Digital Imaging in Medicine
• /
• v.2 no.1
• /
• pp.74-82
• /
• 1996

This paper were studied the evaluation in compare with the conventional and AMBER of analog images, PACS and CR of digital images which were collected every ten sampling chest images with the J.J.Vucicuh chest evaluated chart, and were measured the chest phantom surface dose and the density of several part in chest images. The evaluated numbers were total 22 persons who were 6 persons of the M.D., 6 of the radiotechnological professors and 10 of the radiotechnologists. The obtained results summarized as following : 1. Approaching the optimum standard density of the several part in chest images drew near at the lung round region density in PACS images, the sternum region density in CR and AMBER images, the heart region density in CR AMBER images, the diaphram region density in AMBER and conventional images. 2. The evaluation measured surface dose were appeared orderly lesser dose at the AMBER images (spine 21 mR, lung 2mR, heart 12mR, apex 6mR) than the conventional images(32 mR), CR images(38mR) and PACS images(81mR). 3. The anatomical physical evaluation marks were taken the highest points at CR images(88.3), and orderly PACS images(82), AMBER images(79.2) and conventional images(65.2). 4. It is exposured with lesser surface dose at the analog images, but analog images leaves much room for image quality improvement, and digital images demand for lesser exposure surface dose, although excellent image quality.

• Journal of the Korean Society of Radiology
• /
• v.17 no.7
• /
• pp.1091-1097
• /
• 2023

Bolus is used in radiation therapy to prescribe an even dose to the tumor when the skin surface is inclined or has irregularities. At this time, the dose to the skin surface increases. Due to the patient's unique body structure and irregular skin, voids may occur between the bolus and the skin, which may reduce the accuracy of treatment. Therefore, in this study, the existing bolus and the self-produced bolus through 3D printing were applied to the nasal area, and the difference between the surface dose after treatment plan and the dose directly measured with an Optically Stimulated luminescence(OSL) dosimeter was compared to the existing bolus. The bolus rate was 97%, PLA 100.33%, ePETELA 75A 100.53%, and ePETELA 85A 100.36%. It was confirmed that there was little error in the measurement values and treatment plan values for each material. In addition, compared to when applying a conventional bolus, a difference of -3% to +0.5% for a 3D printed bolus can be confirmed, so a customized bolus produced through 3D printing can complement the shortcomings of the existing bolus. It is believed that there will be.

• Proceedings of the Korean Society of Medical Physics Conference
• /
• 2003.09a
• /
• pp.82-82
• /
• 2003

Introduction: With the development of dose calculation algorithms for electron beams, 3D RTP systerns are available for electron beam dose distribution commercially. However, no studies evaluated the accuracy of dose calculation with ADAC Pinnacle system for electron beams. So, the accuracy of the ADAC system is investigated by comparing electron dose distributions from ADAC system against the BEAMnrc/DOSXYZnrc. Methods: A total of 33 breast cancer patients treated with 6, 9, and 12MeV electrons in our institution was selected for this study. The first part of this study is to compare the dose distributions of measurement, TPS and the BEAMnrc/DOSXYZnrc code in flat water phantom at gantry zero position and for a 10 ${\times}$ 10 $\textrm{cm}^2$ field. The second part is to evaluate the monitor unit obtained from measurement and TPS. Adding actual breast patient's irregular blocks to the first part, monitor units to deliver 100 cGy to the dose maximum (dmax) were calculated from measurement and 3D RTP system. In addition, the dose distributions using blocks were compared between TPS and the BEAMnrc/DOSXYZnrc code. Finally, the effects of tissue inhomogeneities were studied by comparing dose distributions from Pinnacle and Monte Carlo method on CT data sets. Results: The dose distributions calculated using water phantom by the TPS and the BEAMnrc/ DOSXYZnrc code agreed well with measured data within 2% of the maximum dose. The maximum differences of monitor unit between measured and Pinnacle TPS in flat water phantom at gantry zero position were 4% for 6 MeV and 2% for 9 and 12 MeV electrons. In real-patient cases, comparison of depth doses and lateral dose profiles calculated by the Pinnacle TPS, with BEAMnrc/DOSXYZnrc code has generally shown good agreement with relative difference less than +/-3%. Discussion: For comparisons of real-patient cases, the maximum differences between the TPS and BEAMnrc/DOSXYZnrc on CT data were 10%. These discrepancies were due in part to the inaccurate dose calculation of the TPS, so that it needs to be improved properly. Conclusions: On the basis of the results presented in this study, we can conclude that the ADAC Pinnacle system for electron beams is capable of giving results absolutely comparable to those of a Monte Carlo calculation.

• Journal of Radiation Protection and Research
• /
• v.44 no.4
• /
• pp.156-160
• /
• 2019

Background: To compare the dose of radiation received by the fetus in a pregnant patient irradiated for head and neck cancer using helical tomotherapy and three-dimensional conformal radiation therapy (3DCRT). Materials and Methods: The patient was modeled with a humanoid phantom to mimic a gestation of 26 weeks. Radiotherapy with a total dose of 2 Gy was delivered with both tomotherapy (2.5 and 5.0 cm jaw size) and 3DCRT. The position of the fetus was predicted to be 45 cm from the field edge at the time of treatment. The delivered dose was measured according to the distance from the field edge and the fetus. Results and Discussion: The accumulated dose to the fetus was 1.6 cGy by 3DCRT and 2 and 2.3 cGy by the 2.5 and 5 cm jaw tomotherapy plans. For tomotherapy, the fetal dose with the 2.5 cm jaw was lower than that with the 5 cm jaw, although the radiation leakage was greater for 2.5 cm jaw plan due to the 1.5 fold longer beam-on time. At the uterine fundus, tomotherapy with a 5 cm jaw delivered the highest dose of 2.4 cGy. When the fetus moves up to 35 cm at the 29th week of gestation, the resultant fetal doses for 3DCRT and tomotherapy with 2.5 and 5 cm jaws were estimated as 2.1, 2.7, and 3.9 cGy, respectively. Conclusion: For tomotherapy, scattering radiation was more important due to the high monitor unit values. Therefore, selecting a smaller jaw size for tomotherapy may reduce the fetal dose. however, evaluation of risk should be individually performed for each patient.