• Journal of Radiation Protection and Research
• /
• v.44 no.3
• /
• pp.103-109
• /
• 2019

Background: Four-dimensional computed tomographic (4DCT) images are increasingly used in clinic with the growing need to account for the respiratory motion of the patient during radiation treatment. One of the reason s that makes the dose evaluation using 4DCT inaccurate is a change of the patient respiration during the treatment session, i.e., intrafractional uncertainty. Especially, when the amplitude of the patient respiration is greater than the respiration range during the 4DCT acquisition, such an organ motion from the larger respiration is difficult to be represented with the 4DCT. In this paper, the method to generate images expecting the organ motion from a respiration with extended amplitude was proposed and examined. Materials and Methods: We propose a method to generate extra-phase images from a given set of the 4DCT images using deformable image registration (DIR) and linear extrapolation. Deformation vector fields (DVF) are calculated from the given set of images, then extrapolated according to respiratory surrogate. The extra-phase images are generated by applying the extrapolated DVFs to the existing 4DCT images. The proposed method was tested with the 4DCT of a physical 4D phantom. Results and Discussion: The tumor position in the generated extra-phase image was in a good agreement with that in the gold-standard image which is separately acquired, using the same 4DCT machine, with a larger range of respiration. It was also found that we can generate the best quality extra-phase image by using the maximum inhalation phase (T0) and maximum exhalation phase (T50) images for extrapolation. Conclusion: In the present study, a method to construct extra-phase images that represent expanded respiratory motion of the patient has been proposed and tested. The movement of organs from a larger respiration amplitude can be predicted by the proposed method. We believe the method may be utilized for realistic simulation of radiation therapy.

• Journal of the Korean Society of Radiology
• /
• v.5 no.6
• /
• pp.343-349
• /
• 2011

This study was aimed to evaluate the absorbed dose in brain of dental radiography. For radiographic exposure, PLD(photoluminescence dosimetry) chips placed in Rando phantom to measurement the absorbed dose to pituitary gland, orbit, maxillary sinus and submandibular glands, thyroid gland, esophagus. Equipments were used Kodak 2200, Kodak 8000C dental radiographic systems and computed tomography(Lightspeed VCT). The absorbed doses were measured at the same exposure parameters and distance by the clinical factor(kV, mA, sec). The result were as follows ; The absorbed dose for intra-oral radiography were 0.02~2.47cGy, the greatest absorbed dose was 2.47cGy for thyroid gland in maxillary right molar projection. the lowest adsorbed dose was 0.02cGy for submandibular glands in lower anterior projection. The absorbed dose for extra-oral radiography were 0.36~3.44cGy of cephalometric method, 0.14~12.82cGy of panoramic method, 8.17~253.63cGy of computed tomography, the greatest adsorbed dose was 253.63cGy for submandibular glands in maxillary CT scan. the lowest adsorbed dose was 0.14cGy for orbit in panoramic method. As a result, extra-oral radiography was measured more than intra-oral radiography. In particular, method which used computed tomography was measured more than 100 times than intra-oral radiography highly. Therefore, you must show a guideline in extra-oral radiography and an effort to reduce absorbed dose is demanded.

• Tuberculosis and Respiratory Diseases
• /
• v.85 no.1
• /
• pp.25-36
• /
• 2022

Background: Only a few studies directly compared the therapeutic efficacy and safety of two pressurized metered-dose inhalers (pMDIs) in asthma. We analyzed the asthma treatment outcomes, safety, and patient preferences using formoterol/beclomethasone (FORM/BDP), a pMDI with extra-fine particles, compared with formoterol/budesonide (FORM/BUD), another pMDI with non-extra-fine particles. Methods: In this randomized, double-blind, double-dummy parallel group study, 40 adult asthmatics were randomized to FORM/BDP group (n=18; active FORM/BDP and placebo FORM/BUD) or FORM/BUD group (n=22; active FORM/BUD and placebo FORM/BDP). During the two visits (baseline and end of 8-week treatment), subjects were asked to answer questionnaires including asthma control test (ACT), asthma control questionnaires (ACQ), and Quality of Life Questionnaire for Adult Korean Asthmatics (QLQAKA). Lung function, compliance with inhaler, and inhaler-handling skills were also assessed. Results: Ten subjects in the FORM/BDP group and 14 in the FORM/BUD group completed follow-up visits. ACT, ACQ, QLQAKA (a primary outcome), and adverse events did not differ between two groups. We found that the increase in forced expiratory volume in 1 second/forced vital capacity and forced expiratory flow at 25% to 75% of the pulmonary volume in the FORM/BDP group was higher than in the FORM/BUD group. Regarding preference, subjects responded that the flume velocity of FORM/BDP was higher, but more adequate than that of FORM/BUD. They also answered that FORM/BDP reached the trachea and bronchus and irritated them significantly more than FORM/BUD. Conclusion: The use of pMDI with extra-fine particles may relieve small airway obstruction more than the one with non-extra-fine particles despite no significant differences in overall treatment outcomes. Some asthmatics have a misconception about the adequacy of high flume velocity of pMDIs.

• Journal of the Korean Society of Radiology
• /
• v.7 no.2
• /
• pp.145-149
• /
• 2013

Helical Tomotherapy is an innovative means of delivering intensity modulated radiation therapy (IMRT) using a device that merges features of a linear accelerator and helical computed tomography (CT) scanner. Hereat, during helical tomotherapy process, megavoltage computed tomography (MVCT) image are usually used for guiding the precise set-up of patient before/after treatment delivery. But which would certainly increase the total dose for patients, this study was to investigate the imaging dose of MVCT using the cylindrical "Cheese" phantom on a tomotherapy machine. A set of cylindrical "Cheese" phantom was adopted for scanning with respectively pitch value (1, 2, 3 mm) with same number slice (10 slice), same length (approximately 9 cm) and phantom set-ups on the couch of tomotherapy system. The average MVCT imaging dose were measured using A1SL ion chamber inserted in the phantom with preset geometry. The MVCT scanning average dose for the cylindrical "Cheese" phantom was 2.24 cGy, 1.02 cGy, 0.81 cGy during respectively pitch value (pitch 1, 2, 3 mm) with same number slice (10 slice), and same length's average dose was 2.47 cGy, 1.28 cGy, 0.88 cGy respectively (pitch 1, 2, 3 mm). Two major parameters, the assigned pitch numbers and scanning length, where the most important impacts to the dose variation. The MVCT dose was inversely proportional to the CT pitch value. The results may provide a reliable guidance for proper planning design of the scanning region, which is valuable to help minimize the extra dose to patient. Questionnaires were distributed to Radiology departments at hospitals with 300 sickbeds throughout the Pohang region of North Gyeongsang Province concerning awareness and performance levels of infection control. The investigation included measurements of the pollution levels of imaging equipment and assistive apparatuses in order to prepare a plan for the activation of prevention and management of hospital infections. The survey was designed to question respondents in regards to personal data, infection management prevention education, and infection management guidelines.

• The Korean Journal of Physiology
• /
• v.19 no.1
• /
• pp.1-13
• /
• 1985

The influences of $Ca^{2+}-antagonists$, verapamil and $Mn^{2+}$, upon the spontaneous electrical activity and contractions were studied in guinea-pig taenia coli. Spontaneous contractions were recorded with force transducer, and spike action potentials were measured extracellularly by use of suction electrode. All experiments were performed in tris-buffered Tyrode solution Which was aerated With 100% $O_2$ and kept at $35^{\circ}C$. The results obtained were as follows : 1) Verapamil suppressed the frequency and amplitude of spontaneous contractions dose dependently, and blocked completely mechanical responses at the concentration of 1 mg/1. 2) The frequency of bursts of spike discharge(bursts frequency) and the number of spikes in a burst(spikes frequency) were reduced in a dose·dependent manner within the concentration range of $10^{-5}$ to $10^{-3}g/l$, and bursts frequency was affected more readily at a low concentration of $10^{-5}g/l$ verapamil. 3) The verapamil_induced suppression of spontaneous contractions in the Tyrode solution containing 1 mM $Ca^{2+}$ was completely antagonized by the addition of extra $Ca^{2+}$ to the Tyrode solution $(2\;m\;MCa^{2+})$. 4) $Mn^{2+}$ suppressed the amplitude of spontaneous contractions, whereas $Mn^{2+}$ accelerated the frequency dose-dependently within the range of low concentrations$(10^{-7}\;to\;10^{-4}\;M\;Mn^{2+})$. 5) The bursts frequency determining frequency of spontaneous contractions was increased in a dose-dependent manner, whereas the spikes frequency known to determine the contractions amplitude was reduced within the range of low concentrations. At a high concentration of 1 mM $Mn^{2+}$, however, all spontaneous contractile responses were blocked simultaneously with the disapperance of electrical activity. 6) The frequency and amplitude of spontaneous contractions altered by $Mn^{2+}$ in 1mM $Ca^{2+}$ Tyrode were increased by extra $Ca^{2+}(2mM)$.

• The Journal of the Acoustical Society of Korea
• /
• v.41 no.3
• /
• pp.367-374
• /
• 2022

In this paper, correlation analysis between speech characteristics and the dose of antipsychotic drugs was performed. To investigate the pattern of speech characteristics of ExtraPyramidal Symptoms (EPS) related to voice change, a common side effect of antipsychotic drugs, a Korean-based extrapyramidal symptom speech corpus was constructed through the sentence development. Through this, speech patterns of EPS and non-EPS groups were investigated, and in particular, a strong speech feature correlation was shown in the EPS group. In addition, it was confirmed that the type of speech sentence affects the speech feature pattern, and these results suggest the possibility of early detection of antipsychotics-induced EPS based on the speech features.

• Progress in Medical Physics
• /
• v.34 no.4
• /
• pp.48-54
• /
• 2023

Purpose: In this study, the dosimetric characteristics of lung stereotactic body radiotherapy (SBRT) plans using the new Halcyon system were analyzed to assess its suitability. Methods: We compared the key dosimetric parameters calculated for the Halcyon SBRT plans with those of a conventional C-arm linear accelerator (LINAC) equipped with a high-definition multileaf collimator (HD-MLC)-Trilogy Tx. A total of 10 patients with non-small-cell lung cancer were selected, and all SBRT plans were generated using the RapidArc technique. Results: Trilogy Tx exhibited significant superiority over Halcyon in terms of target dose coverage (conformity index, homogeneity index, D_{0.1 cc}, and D_95%) and dose spillage (gradient). Trilogy Tx was more efficient than Halcyon in the lung SBRT beam delivery process in terms of the total number of monitor units, modulation factor, and beam-on time. However, it was feasible to achieve a dose distribution that met SBRT plan requirements using Halcyon, with no significant differences in satisfying organs at risk dose constraints between both plans. Conclusions: Results confirm that Halcyon is a viable alternative for performing lung SBRT in the absence of a LINAC equipped with HD-MLC. However, extra consideration should be taken in determining whether to use Halcyon when the planning target volume setting is enormous, as in the case of significant tumor motions.

• Progress in Medical Physics
• /
• v.3 no.2
• /
• pp.1-12
• /
• 1992

For intraoperative radiation therapy using electron beams, a cone system to deliver a large dose to the tumor during surgical operation and to save the surrounding normal tissue should be developed and dosimetry for the cone system is necessary to find proper X-ray collimator setting as well as to get useful data for clinical use. We developed a docking type of a cone system consisting of two parts made of aluminum: holder and cone. The cones which range from 4cm to 9cm with 1cm step at 100cm SSD of photon beam are 28cm long circular tubular cylinders. The system has two 26cm long holders: one for the cones larger than or equal to 7cm diamter and another for the smaller ones than 7cm. On the side of the holder is an aperture for insertion of a lamp and mirror to observe treatment field. Depth dose curve. dose profile and output factor at dept of dose maximum. and dose distribution in water for each cone size were measured with a p-type silicone detector controlled by a linear scanner for several extra opening of X-ray collimators. For a combination of electron energy and cone size, the opening of the X-ray collimator was caused to the surface dose, depths of dose maximum and 80%, dose profile and output factor. The variation of the output factor was the most remarkable. The output factors of 9MeV electron, as an example, range from 0.637 to 1.549. The opening of X-ray collimators would cause the quantity of scattered electrons coming to the IORT cone system. which in turn would change the dose distribution as well as the output factor. Dosimetry for an IORT cone system is inevitable to minimize uncertainty in the clinical use.

• Radiation Oncology Journal
• /
• v.32 no.1
• /
• pp.7-13
• /
• 2014

Purpose: To evaluate the results of postoperative radiotherapy in patients with extra-hepatic bile duct cancer (EHBDC) and identify the prognostic factors for local control and survival. Materials and Methods: Between January 2001 and December 2010, we retrospectively reviewed the cases of 70 patients with EHBDC who had undergone curative resection and received postoperative radiotherapy. The median radiation dose was 50.4 Gy (range, 41.4 to 54 Gy). The resection margin status was R0 in 30 patients (42.9%), R1 in 25 patients (35.7%), and R2 in 15 patients (21.4%). Results: The 5-year rates of overall survival (OS), event-free survival (EFS), and locoregional control (LRC) for all patients were 42.9%, 38.3%, and 61.2%, respectively. The major pattern of failure was distant relapses (33 patients, 47.1%). A multivariate analysis showed that the postradiotherapy CA19-9 level, radiation dose (${\geq}50$ Gy), R2 resection margins, perineural invasion, and T stage were the significant prognostic factors for OS, EFS, and LRC. OS was not significantly different between the patients receiving R0 and R1 resections, but was significantly lower among those receiving R2 resection (54.6%, 56.1%, and 7.1% for R0, R1, and R2 resections, respectively). Conclusion: In patients with EHBDC who had undergone curative resection, a postoperative radiotherapy dose less than 50 Gy was suboptimal for OS and LRC. Higher radiation doses may be needed to obtain better LRC. Further investigation of novel therapy or palliative treatment should be considered for patients receiving R2 resection.

• Korean Journal of Ecology and Environment
• /
• v.50 no.1
• /
• pp.16-28
• /
• 2017

In an aquatic environment, toxicity of metals to organisms depends on external factors (type of metal, exposure concentration and duration, environmental parameters, and water quality) and intracellular processes(metal-binding sites and detoxification). Toxicity of copper(Cu) on the marine microalga Tetraselmis suecica was investigated in this study. Dose-dependent (Cu concentration dependent) inhibition of growth and cell division, as well as, variation of intra- and extra-cellular Cu, Fe and Zn content was observed. T. suecica was sensitive to Cu; the 96 h $EC_{50}$ (concentration to inhibit growth-rate by 50%) of growth rate (${\mu}$) ($21.73{\mu}M\;L^{-1}$), cell division $day^{-1}$ ($18.39{\mu}M\;L^{-1}$), and cells $mL^{-1}$ ($13.25{\mu}M\;L^{-1}$) demonstrate the toxicity of Cu on this microalga. High intra-($19.86Pg\;cell^{-1}$) and extra-cellular($54.73Pg\;cell^{-1}$) Cu concentrations were recorded, on exposure to 24.3 and $72.9{\mu}M\;L^{-1}$ of Cu.