• The Journal of Korean Society for Radiation Therapy
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• v.15 no.1
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• pp.67-77
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• 2003

I. Purpose Uniform dose distribution of the whole body is essential factor for the total body irradiation(TBI). In order to achieved this goal, we used to compensation filter to compensate body contour irregularity and thickness differences. But we can not compensate components of body, namely lung or bone. The purpose of this study is evaluation of dose attenuation in bone tissue when TBI using diode detectors and TLD system. II. Materials and Methods The object of this study were 5 patients who undergo TBI at our hospital. Dosimetry system were diode detectors and TLD system. Treatment method was bilateral and delivered 10MV X-ray from linear accelerator. Measurement points were head, neck, pelvis, knees and ankles. TLD used two patients and diode detectors used three patients. III. Results Results are as followed. All measured dose value were normalized skin dose. TLD dosimetry : Measured skin dose of head, neck, pelvis, knees and ankles were $92.78{\pm}3.3,\;104.34{\pm}2.3,\;98.03{\pm}1.4,\;99.9{\pm}2.53,\;98.17{\pm}0.56$ respectably. Measured mid-depth dose of pelvis, knees and ankles were $86{\pm}1.82,\;93.24{\pm}2.53,\;91.50{\pm}2.84$ respectably. There were $6.67\%{\sim}11.65\%$ dose attenuation at mid-depth in pelvis, knees and ankles. Diode detector : Measured skin dose of head, neck, pelvis, knees and ankles were $95.23{\pm}1.18,\;98.33{\pm}0.6,\;93.5{\pm}1.5,\;87.3{\pm}1.5,\;86.90{\pm}1.16$ respectably. There were $4.53\%{\sim}12.6\%$ dose attenuation at mid-depth in pelvis, knees and ankles. IV. Conclusion We concluded that dose measurement with TLD or diode detector was inevitable when TBI treatment. Considered dose attenuation in bone tissue, We must have adequately deduction of compensator thickness that body portion involved bone tissue.

• Journal of The Korean Radiological Technologist Association
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• v.29 no.1
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• pp.6-11
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• 2003

목적 : 전신방사선조사(TBI)시 균등한 선량을 조사할 목적으로 사용되는 각 신체부위별 보상체(compensator) 두께의 결정은 열형광선량계(TLD)를 이용하여 표면선량(surface dose)을 측정하고, 심부선량(depth dose)으로 환산하는 방법을 주로 이용한다. 그러나 이와 같은 방법은 골(bone) 조직에 대한 선량감쇠(dose attenuation)의 영향이 고려되지 않아 신체중심부에서의 정확한 심부선량을 알 수가 없다. 이에 본 연구

• Journal of radiological science and technology
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• v.29 no.3
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• pp.185-195
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• 2006

Purpose: This study investigated the status of radiation exposure doses since the establishment of the "Regulations on Safety Management of Diagnostic Radiation Generation Device" in January 6, 1995. Method: The level of radiation exposure in people engaged or having been engaged in radiation-related industries of inspection organizations, educational organizations, military units, hospitals, public health centers, businesses, research organizations or clinics over a 5 year period from Jan. 1, 2000 to Dec. 31, 2004 was measured. The 149,205 measurement data of 57,136 workers registered in a measurement organization were analysed in this study. Frequency analysis, a Chi-square test, Chi-square trend test, and ANOVA was used for data analysis. Results: Among 57,136, men were 40,870(71.5%). 50.3% of them were radiologic technologists, otherwise medical doctors(22.7%), nurse(2.9%) and others(24.1%). The average of depth radiation and surface radiation during the 5-year period were found to decrease each year. Both the depth radiation and surface radiation exposure were significantly higher in males, in older age groups, in radiological technologists of occupation. The departments of nuclear medicine had the highest exposure of both depth and surface radiation of the divisions of labor. There were 1.98 and 2.57 per 1,000 person-year were exposed more than 20 mSv(limit recommended by International Commission on Radiological Protection) in depth and surface radiation consequently. Conclusion: The total exposure per worker was siginifcantly decreased by year. But Careful awareness is needed for the workers who exposed over 20 mSv per year. In order to minimize exposure to radiation, each person engaged in a radiation-related industry must adhere to the individual safety management guidelines more thoroughly. In addition, systematic education and continuous guidance aimed at increasing the awareness of safety must be provided.

• The Journal of Korean Society for Radiation Therapy
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• v.14 no.1
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• pp.79-84
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• 2002

The main cause factor for effective the output, especially in small & irregular shaped field of electron beam therapy, are collimation system, insert block diameter and energy. In the absorption deose of treatment fields, we should consider the lateral build-up ratio (LBR), which the ratio of dose at a point at depth for a given circular field to the dose at the same point for a 'broad-field', for the same incident fluence and profile. The LBR data for a small circular field are used to extract radial spread of the pencil beam, ${\sigma}$, as a function of depth and energy. It's based on elementary pencil beam. We consider availability of the factor, ${\sigma}$, in the small & irregular fields electron beam treatment.

• Journal of The Korean Radiological Technologist Association
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• v.27 no.2
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• pp.57-65
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• 2001

This study was performed to measure about exposure dose during simple abdomen x-ray Radiography. The exposure dose was measured by PDD, surface dose, percentage scatter dose, respectively. The result was as followed: 1. When tube voltage were increased wi

• The Journal of the Korea Contents Association
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• v.9 no.6
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• pp.247-255
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• 2009

This study aims to provide basic data for establishing the safety and health plan by investigating the exposure conditions in the facilities registering business about handling radiations and radioactive isotopes in Korea. dose levels(working space, worker location) of the workers in 153 facilities were measured using surveymeter, and individual exposure concentration[(shallow dose(SD), depth dose(DD)] in 27 facilities using thermal luminescence dosimeter(TLD). In accordance with the measurement results by business type[fire fighting prevention business(FFPB, n=10), financial insurance business(FIB, n=3) and other facilities(n=140)] using surveymeter, those three business type groups showed difference (p<0.000). Dose levels of worker location for FFPB and FIB were significantly higher than 10.0 ${\mu}Sv$/hr, the allowable standard for radiations and radioactive isotopes, and they were higher 109.3 times(p<0.000) and 187.5 times(p<0.000) than those in other facilities. The concentration of TLD[FFPB(n=10), other facility (n=17)] in DD of FFPB was significantly higher than that in other facility(p=0.05). In accordance with the analysis result on relationship between surveymeter and TLD, the dose on working space and worker location(r=0.406, p<0.05), worker location dose and SD(r=0.453, p<0.05), worker location dose and DD(r=0.553, p<0.01), and SD and DD(r=0.927, p<0.001) had all related each other. It is urgently required to change FFPB and FIB from the facilities requiring registration for handling radiations and radioactive isotopes to the facilities that shall get permission for handling radiations and radioactive isotopes by reestablishing the legal administration area, for safety and health of radiation occupants.

• The Journal of the Korea Contents Association
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• v.12 no.12
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• pp.329-334
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• 2012

For the dosimetry of the radiation workers, film badge, Thermo Luminescent Dosimeter (TLD), and glass dosimeter are being used and recently, there is a growing trend of using Optically Stimulated Luminescence Dosimeter (OSLD) in the world. However, OSLD is only being applied some of the field in Korea and there has been almost no study made related to OSLD. Thus, the accumulated radiation dose of TLD and OSLD that have been most frequently used in the field was compared in the radiation workers of nuclear medicine and their working areasfor 3 months. As a result, the average surface dose showed 0.85 mSv difference with 1.27 mSv for TLD and 2.12 mSv for OSLD while having 0.73 mSv difference for the average depth dose with 1.33 mSv for TLD and 2.06 mSv for OSLD. The surface dose and depth dose of OSLD showed statistically significant result with higher measurement (p<0.05).

• Journal of the Korean Society of Radiology
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• v.12 no.4
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• pp.443-450
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• 2018

The Geant 4 simulated the linear accelerator (VARIAN CLINAC) based on the previously implemented BEAMnrC data, using the head structure of the linear accelerator. In the 10 MV photon flux, Geant4 was compared with the measured value of the percentage of the deep dose and the lateral dose of the water phantom. In order to apply the dose calculation to the body part, the actual patient's lung area was scanned at 5 mm intervals. Geant4 dose distributions were obtained by irradiating 10 MV photons at the irradiation field ($5{\times}5cm^2$) and SAD 100 cm of the water phantom. This result is difficult to measure the dose absorbed in the actual lung of the patient so the doses by the treatment planning system were compared. The deep dose curve measured by water phantom and the deep dose curve calculated by Geant4 were well within ${\pm}3%$ of most depths except the build-up area. However, at the 5 cm and 20 cm sites, 2.95% and 2.87% were somewhat higher in the calculation of the dose using Geant4. These two points were confirmed by the geometry file of Genat4, and it was found that the dose was increased because thoracic spine and sternum were located. In cone beam CT, the dose distribution error of the lungs was similar within 3%. Therefore, if the contour map of the dose can be directly expressed in the DICOM file when calculating the dose using Geant4, the clinical application of Geant4 will be used variously.

• The Journal of Korean Society for Radiation Therapy
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• v.29 no.2
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• pp.43-51
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• 2017

Purpose: The purpose of this study is to evaluate the dosimetric effects of couch attenuation and air gaps using 3D phantom for prone breast radiation therapy. Materials and method: A 3D printer(Builder Extreme 1000) and computed tomography (CT) images of a breast cancer patient were used to manufacture the customized breast phantom. Eclipse External Beam Planning 13.6 (Varian Medical Systems Palo Alto, CA, USA) was used to create the treatment plan with a dose of 200 cGy per fraction with 6 MV energy. The Optically Stimulated Luminescence Detector(OSLD) was used to measure the skin dose at four points (Med 1, Med 2, Lat 1, Lat 2) on the 3D phantom and ion-chamber (FC65-G) were used to perform the in-vivo dosimetry at the two points (Anterior, Posterior). The Skin dose and in-vivo dosimetry were measured with reference air gap (3 cm) and increased air gaps (1, 2, 3, 4, 5, 6 cm) from reference distance between the couch and 3D phantom. Results: As a result, measurement for the skin dose at lateral point showed a similar value within ${\pm}4%$ compared to the plan. While the air gap increased, skin dose at medial 1 was reduced. And it was also reduced over 7 % when the air gap was more than 3 cm compared to radiation therapy plan. At medial 2 it was reduced over 4 % as well. The changes of dose from variety of the air gap showed similar value within ${\pm}1%$ at posterior. As the air gap was increased, the dose at anterior was also increased and it was increased by 1 % from the air gap distance more than 3 cm. Conclusion: Dosimetrical measurement using 3D phantom is very useful to evaluate the dosimetric effects of couch attenuation and air gaps for prone breast radiation therapy. And it is possible to reduce the skin dose and increase the accuracy of the radiation dose delivery by appling the optimized air gap.

• Progress in Medical Physics
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• v.4 no.1
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• pp.29-39
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• 1993

Electron beams have found unique and complementary used in the treatment of cancer, but it's very difficult to delineate dose distribution, because of multi-collisions. Numerical solution is more usefull to describe electron distributed in tissue. A semi-empirical eqution is given for the dose at any point at various depths in water. This equation is a modificated model which was based on solutions of a general age diffusion equation. Parameters have been calulated from electron beams data with energies 6～18MeV form a LINAC for use in computerised dosimetry calculations. The depth doses and isodose curves are predicted as a function of the practical range, source skin distance and field size. Depth dose accuracy have been achieved 2% above 50% depth dose and 5% at lower doses, relative to maximum dose. Also, the shape of the isodose curves with the constrictions at higher dose and bulging ot lower values are accurately predicted. Computer calculated beams have been used to generate ever isodose distribution for certain clinical situations.