• Journal of The Korean Radiological Technologist Association
• /
• v.30 no.1
• /
• pp.49-57
• /
• 2004

I. Purpose : Measure the absolute point dose and film dosimetry in intensity modulated radiation therapy (IMRT) of head and neck cancers. A comparison of objective view between measured and calculated dose dlistribution look through optimization algorithm

• Journal of the Korea Safety Management & Science
• /
• v.17 no.4
• /
• pp.207-212
• /
• 2015

When performing Chest x-ray examination to pregnant woman, normally we shield back side of abdomen. In this situation, scattered rays made by equipment and surrounding structure can enter front side of abdomen. Therefore, in this study, we evaluate suitability of abdomen shield especially to pregnant woman. In case of One shielding material placed back of abdomen, the measured value is $0.676{\pm}0.19uSv/hr$. Two shielding material is $0.764{\pm}0.04uSv/hr$. Three is $0.685{\pm}0.16uSv/hr$. The exposure dose inferred in this study does not excess annual effective dose limit. But It is not mean absolute safety. So we have to minimize occurrence of stochastic effect of radiosensitivity by shielding front side of abdomen of pregnant woman in clinic.

• Journal of radiological science and technology
• /
• v.19 no.2
• /
• pp.71-77
• /
• 1996

Studies were conducted to determine the clinical application of photodiode. We compared photodiode with ion-chamber as to change of tube potential, tube current, mAs and measured decreasing rate of penetration dose. When tube potential was changed from 60 kVp to 120 kVp, output of photodiode and ion-chamber were changed from 0.4 to 1.625, and 1.018 to 4.268, respectively. This was a good agreement to theory that $I=Kv^2it$(I is intensity, K is constant, v is tube potential, i is tube current, t is time). Characteristics for change of tube current and mAs were also a good agreement to theory. And comparison in decreasing rate of penetration dose was similar except above 6 cm in depth. Our results indicated that photodiode was a good instrument for relative measurement of radiation exposure, but we can not use the photodiode for absolute radiation dose.

• Toxicological Research
• /
• v.20 no.4
• /
• pp.339-348
• /
• 2004

Paecilomyces sinclairii was administered ad libitum feeding at percentage levels of 0, 1.25, 2.5, 5 and 10 percentage (calculated about 8 g/kg)/feeder for a period of 3 months. There was no observed clinical signs or deaths related to treatment in all groups tested. Therefore, the approximate lethal dose of P. sinclairii was considered to be higher than 8 g/kg in rats. Mild decreases in body weight gain were observed dose-dependently in P. sinclairii treated groups in dose response manner after 2 weeks. Interestingly, the weight of abdominal adipose tissues surrounding epididymides were greatly reduced by this Dongchunghacho, in parallel with the mild increase in body weight gain. However, the absolute weight change of other organs was not observed. There were not significantly different from the control group in urinalysis, ocular examination, hematological, serum biochemical value and histopathological examination. From these results, it is concluded that the no-observed-adverse-effect level (NOAEL) of P. sinclairii is less than 1.25% (1 g/kg) in rats in the present study.

• Asian Pacific Journal of Cancer Prevention
• /
• v.13 no.3
• /
• pp.985-989
• /
• 2012

Objective: To make sure the feasibility with $^{18F}FDG$ PET/CT to guided dynamic intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma patients, by dosimetric verification before treatment. Methods: Chose 11 patients in III~IVA nasopharyngeal carcinoma treated with functional image-guided IMRT and absolute and relative dosimetric verification by Varian 23EX LA, ionization chamber, 2DICA of I'mRT Matrixx and IBA detachable phantom. Drawing outline and making treatment plan were by different imaging techniques (CT and $^{18F}FDG$ PET/CT). The dose distributions of the various regional were realized by SMART. Results: The absolute mean errors of interest area were $2.39%{\pm}0.66$ using 0.6cc ice chamber. Results using DTA method, the average relative dose measurements within our protocol (3%, 3 mm) were 87.64% at 300 MU/min in all filed. Conclusions: Dosimetric verification before IMRT is obligatory and necessary. Ionization chamber and 2DICA of I'mRT Matrixx was the effective dosimetric verification tool for primary focal hyper metabolism in functional image-guided dynamic IMRT for nasopharyngeal carcinoma. Our preliminary evidence indicates that functional image-guided dynamic IMRT is feasible.

• Korean Journal of Veterinary Research
• /
• v.35 no.3
• /
• pp.437-445
• /
• 1995

This experiment was carried out to study the preventive effect of cysteine on the toxicities of captafol to the hematological and serum biochemical values. A single dose of captafol(5mg/kg BW, ip) was given to male Sprague-Dawley rats and its toxicities were evalutated by body weitht changes, autopsy findings, absolute organ weight, and hematological and serum biochemical parameters. The single dose of captafol caused significant decreases in body weitht, and absolute liver weight, as-cites, fibrin clot in abdominal cavity, adhesion of liver lobes significant elevation of number of RBC, hemoglobin concentration and serum AST activity, and decreased of serum phospholipid level. Where as cysteine(over 58mg/kg BW) given immediately after captafol appeared to prevent the ascites, fibrin clot in abdominal cavity and liver lobe adhesion. It also prevented the liver and blood, especially RBC toxicites. The results suggest that cysteine and other compounds containing sulfhydryl groups may protect the subjects from captafol-induced toxicity.

• The Journal of Korean Society for Radiation Therapy
• /
• v.33
• /
• pp.145-153
• /
• 2021

Purpose: The purpose of this study is to evaluate the ovarian dose during radiation therapy for breast cancer in women of childbearing age through an experiment. The ovarian dose is evaluated by comparing and analyzing between the calculated dose in the treatment planning system according to the treatment technique and the measured dose using a thermoluminescence dosimeter (TLD). The clinical usefulness of lead (Pb) apron is investigated through dose analysis according to whether or not it is used. Materials and Methods: Rando humanoid phantom was used for measurement, and wedge filter radiation therapy, 3D conformal radiation therapy, and intensity modulated radiation therapy were used as treatment techniques. A treatment plan was established so that 95% of the prescribed dose could be delivered to the right breast of the Rando humanoid phantom 3D image obtained using the CT simulator. TLD was inserted into the surface and depth of the virtual ovary of the Rando hunmanoid phantom and irradiated with radiation. The measurement location was the center of treatment and the point moved 2 cm to the opposite breast from the center of the Rando hunmanoid phantom, 5cm, 10cm, 12.5cm, 15cm, 17.5cm, 20cm from the boundary of the right breast to the center of treatment and downward, and the surface and depth of the right ovary. Measurements were made at a total of 9 central points. In the dose comparison of treatment planning systems, two wedge filter treatment techniques, three-dimensional conformal radiotherapy, and intensity-modulated radiation therapy were established and compared. Treatments were compared, and dose measurements according to the use of lead apron were compared and analyzed in intensity-modulated radiation therapy. The measured value was calculated by averaging three TLD values for each point and converting using the TLD calibration value, which was calculated as the point dose mean value. In order to compare the treatment plan value with the actual measured value, the absolute dose value was measured and compared at each point (%Diff). Results: At Point A, the center of treatment, a maximum of 201.7cGy was obtained in the treatment planning system, and a maximum of 200.6cGy was obtained in the TLD. In all treatment planning systems, 0cGy was calculated from Point G, which is a point 17.5cm downward from the breast interface. As a result of TLD, a maximum of 2.6cGy was obtained at Point G, and a maximum of 0.9cGy was obtained at Point J, which is the ovarian dose, and the absolute dose was 0.3%~1.3%. The difference in dose according to the use of lead aprons was from a maximum of 2.1cGy to a minimum of 0.1cGy, and the %Diff value was 0.1%~1.1%. Conclusion: In the treatment planning system, the difference in dose according to the three treatment plans did not show a significant difference from 0.85% to 2.45%. In the ovary, the difference between the Rando humanoid phantom's treatment planning system and the actual measured dose was within 0.9%, and the actual measured dose was slightly higher. This did not accurately reflect the effect of scattered radiation in the treatment planning system, and it is thought that the dose of scattered radiation and the dose taken by CBCT with TLD inserted were reflected in the actual measurement. In dosimetry according to the with or without a lead apron, when a lead apron was used, the closer the distance from the treatment range, the more effective the shielding was. Although it is not clinically appropriate for pregnancy or artificial insemination during radiotherapy, the dose irradiated to the ovaries during treatment is not expected to significantly affect the reproductive function of women of childbearing age after radiotherapy. However, since women of childbearing age have constant anxiety, it is thought that psychological stability can be promoted by presenting the data from this study.

• Journal of radiological science and technology
• /
• v.36 no.3
• /
• pp.237-244
• /
• 2013

The purpose of this study is to compare method in the treatment of breast cancer using dose index. And, it is to find the optimized treatment technique to the patient. The phantom filled with tissue-equivalent material were used simulation and treatment as techniques of 3D-CRT, IMRT, VMAT was planned using Eclipse v10. By using HI(homogeneity index), CI(Conformity index), OED(Organ equivalent dose), EAR(Excess Absolute Risk), were assessed for each treatment plans. HI and CI of 3D-CRT, IMRT, VMAT were calculated 16.89, 11.21, 9.55 and 0.59, 0.61, 0.83. The organ average doses of Lt lung, Rt lung, liver, heart, esophagus, cord, Lt breast, trachea and stomach were 0.01 ~ 2.02 Gy, 0.36 ~ 5.01 Gy, 0.25 ~ 2.49 Gy, 0.14 ~ 6.92 Gy, 0.03 ~ 2.02 Gy, 0.01 ~ 1.06 Gy, 0.25 ~ 6.08 Gy, 0.08 ~ 0.59 Gy, 0.01 ~ 1.34 Gy, respectively. The OED, EAR of the IMRT and VMAT show higher than 3D-CRT. As the result of this study, we could confirm being higher dose index(HI, CI) in IMRT and VMAT than 3D-CRT, but doses of around normal organs was higher IMRT, VMAT than 3D-CRT.

• Progress in Medical Physics
• /
• v.29 no.3
• /
• pp.92-100
• /
• 2018

The manufacturer of a linear accelerator (LINAC) has reported that the target melting phenomenon could be caused by a non-recommended output setting and the excessive use of monitor unit (MU) with intensity-modulated radiation therapy (IMRT). Due to these reasons, we observed an unexpected beam interruption during the treatment of a patient in our institution. The target status was inspected and a replacement of the target was determined. After the target replacement, the beam profile was adjusted to the machine commissioning beam data, and the absolute doses-to-water for 6 MV and 10 MV photon beams were calibrated according to American Association of Physicists in Medicine (AAPM) Task Group (TG)-51 protocol. To verify the beam data after target replacement, the beam flatness, symmetry, output factor, and percent depth dose (PDD) were measured and compared with the commissioning data. The difference between the referenced and measured data for flatness and symmetry exhibited a coincidence within 0.3% for both 6 MV and 10 MV, and the difference of the PDD at 10 cm depth ($PDD_{10}$) was also within 0.3% for both photon energies. Also, patient-specific quality assurances (QAs) were performed with gamma analysis using a 2-D diode and ion chamber array detector for eight patients. The average gamma passing rates for all patients for the relative dose distribution was $99.1%{\pm}1.0%$, and those for absolute dose distribution was $97.2%{\pm}2.7%$, which means the gamma analysis results were all clinically acceptable. In this study, we recommend that the beam characteristics, such as beam profile, depth dose, and output factors, should be examined. Further, patient-specific QAs should be performed to verify the changes in the overall beam delivery system when a target replacement is inevitable; although it is more important to check the beam output in a daily routine.

• The Journal of the Korea Contents Association
• /
• v.8 no.11
• /
• pp.203-209
• /
• 2008

Nowadays the risk of radiation is getting more serious, so we must know the exact dose that was irradiated, Because very high radiation dose is used in radiation therapy field. We used the ionization chamber which measure the radiation dose in this study. We tried to know the incorrect result from the distortion of geometric structure of ionization chamber and we studied how to find the distortion of geometric structure of ionization chamber. We used a radio fluoroscopy to find the wound degree of electrode of ionization chamber and a reconstructed 3D CT image to analyze the wound degree of electrode quantitatively. we measured degree of distortion by comparing with absorbed dose of normal electrode and wound electrode. The comparative result is not absolute dosimetry at specific point but relative dosimetry between thats. We measured 4 MV, 10MV photon with same absorbed dose and dose rate. The degree of distortion of wound electrode was totally $5.5{\sim}7.2%$, and there was no difference between two energies. The variation induced from radiation dose to be irradiated and dose rate, and the degree of distortion from wound direction also was almost similar value. We could find that the geometric structure of ionization chamber that can influence a basic measurement of radiation dose can be changed by old usage and inattention of management in this study, especially winding of electrode can be happened, in radiation therapy field, It is very important to keep precise radiation dose quantitatively.