Earticle

임산부는 소량의 방사선 조사일지라도 태아에 영향을 줄 수 있다. 따라서, 대부분의 병원에서는 납치마를 이용한 흉부 X선 촬영을 한다. 이에 임산부는 불편함을 호소하고 있다. 이를 개선하기 위해 콜리메이터에 자체 제작한 부속물을 장착하여 실험하였다. 일반적인 흉부 X선 촬영조건에 표준촬영, 납치마를 이용한 촬영, CA-1을 장착한 촬영을 통해 방사선량율을 측정하고 감소율을 계산하였다. 그 결과, 납치마을 이용한 검사와 거의 비슷한 방사선량율과 감소율을 나타내었다. 이를 통해 납치마를 이용한 임산부 촬영의 불편함을 해소하고, 태아 피폭의 최소화 및 의료영상의 질적인 향상을 유지할 수 있을 것이다.

Pregnant women can affect the fetus even with a small amount of radiation. Therefore, in most hospitals, chest radiography using apron are performed. Accordingly, pregnant women are complaining of discomfort. To improve this, the collimator was equipped with an attached accessory and tested. The radiation dose rate was measured and the reduction rate was calculated through standard chest, radiography using apron, and CA-1. As a result, the radiation dose rate and the reduction rate were almost the same as the test using the apron. Through this, the inconvenience of taking a pregnant woman using an apron can be eliminated, minimizing the exposure of the fetus and maintaining a quality improvement of the medical image.

Opened a court in February 10, 2006, a rule of safety management of the diagnosis radiation system was promulgated for safety of the radiation worker, patients and patients' family members. The purpose of this rule is to minimize the risk of being exposed to radiation during the process of handling X-ray. For this reason, we manufactured shielding device of mobile X-ray unit collimator for diminution of skin dose. Shielding device is made to a thickness of Pb 0.375mm. For portable chest radiography, we measured skin dose 50cm from center ray to 200cm at intervals of 20cm by Unfors Xi detector. As a result, a rule of safety management of the diagnosis radiation system has been strengthened. But there are exceptions, such as ER, OR, ICU to this rule. So shielding device could contribute to protect unnecessary radiation exposure and improve nation's health.

국내 진단용 방사선 발생장치의 수요는 매년 증가하고 있다. 이 장비는 환자에 대한 정확한 검사와 불필요한 피폭이 발생하지 않도록 정도 관리가 필요하다. 이 중 콜리메이터 램프에서 나오는 빛의 밝기과 조사야는 환자의 정확한 검사를 위해 무엇보다 중요하다. 하지만, 디지털 엑스선 촬영장치에서는 아직 엑스선 조사야와 광 조사야의 일치성을 측정하는 정확한 방법이 확립되어 있지 않다. 이에 9개의 동전을 이용하는 실험방법을 바탕으로 또 다른 방법을 제시하여 D 지역의 의원급 30곳에 대해 콜리메이터 램프에서 나오는 조도를 측정하고, 엑스선 조사야와 광 조사야의 일치성을 평가 하였다. 그 결과, D 지역의 의원급 30곳은 모두 적합 판정이 나왔다. 기존의 실험방법을 바탕으로 제시된 이 방법은 특별한 장비가 필요하지 않으며, 엑스선 조사야와 광 조사야의 차이를 쉽게 측정할 수 있는 비교적 편리한 방법이다. 따라서 의료기관에서는 수시로 점검을 하여 영상의 왜곡을 방지할 수 있을 것으로 생각된다.

The demand for domestic diagnostic radiation generators is increasing every year. This equipment requires quality control to accurately examine patients and prevent unnecessary radiation exposure. Among them, the brightness and irradiation field of light from the collimator lamp are most important for accurate examination of patients. However, an accurate method for measuring the congruence of the X-ray field and the light field in a digital X-ray imaging device has not been established. Accordingly, based on the experimental method using 9 coins, another method was proposed to measure the illuminance from the collimator lamp for 30 clinics in area D and evaluate the congruence of the X-ray field and the light field. As a result, all clinics in area D were judged to be suitable. This method, presented based on existing experimental methods, does not require special equipment and is a relatively convenient method that can easily measure the difference between the X-ray field and the light field. Therefore, it is believed that medical institutions can prevent image distortion by conducting frequent inspections.

In order to reduce exposure dose for patient, adjusting a beam of radiation into the shape of a tumor during therapy sessions was performed. Multi-leaf collimator (MLC) serve as a component for increasing the accuracy, efficiency and quality of radiation treatments[1]. In this study, we designed dual layer Multi-leaf collimator(MLC) for X-ray 6MeV in order to reduce unnecessary dose for patient during irradiation time. We investigated and calculated on various materials, configurations for MLC by using Monte Carlo N particle (MCNP6 version). Tungsten alloys were employed as shielding materials and according to the leaf Varian assemble. Shielding rate was measured based on the ratio between photon flux with MCL and without MLC field. The flux was obtained by tally F4 card in MCNP6. Through designing of MLC, the unnecessary dose expose to patient was significant reduced.

This study was designed to assess whether the conventional tangential technique, using a multileaf collimator (MLC), allows a reduced dose to the organs at risk (OAR) in breast radiation therapy. A total of forty right and left 20 for each breast cancer patients that underwent radiation therapy after breast conserving surgery were included in this study. For each patient, the planning target volume (PTV) and OAR (heart, left anterior descending artery (LAD), liver and lung) were defined and dose distribution were produced for conventional tangential beams using 6 MV photons. The treatment plans were made using the following two techniques for all patients. For the first plan (P1), MLC was designed to shield as much of OAR as possible without compromising the coverage of PTV. In the second plan (P2), the treatment plan was created without using MLC. Dose-volume histograms for OARs were calculated for all plans. For left breast cancer, the percentage of maximum dose (Dmax%) and mean dose (Dmean%) of OARs (heart and LAD) were calculated, and for right breast cancer, the percentage of the mean dose (Dmean%) of the liver was calculated. The Dmean% of the lung was calculated in all patients. The mean values of Dmax% of the heart (86.9±19.5% range, 35.1-100.6%) in P1 were significantly lower than in P2 (98.3±3.4% range, 91.7-105.2%) (p=0.001). The mean values of Dmax% of LAD (78.4±22.5% range, 26.5-99.7%) in P1 was significantly lower than in P2 (93.3±8.1% range, 67.9-102.1%) (p<0.001). In P1, the mean values of Dmean% of the liver (4.8±2.0%) were significantly lower than in P2 (6.2±2.5%) (p<0.001). The mean values of Dmean% of the lung were significantly lower in P1 (9.3±2.3%) than in P2 (9.7±2.4%) (p<0.001). P1, by using MLC, allows a significantly reduced dose to OAR compared with P2. We can suggest that it is reasonable to routinely use MLC in the conventional tangential technique for breast radiation therapy considering the primary tumor location.

Background: This work aims to develop a new imaging system based on a pulse shape discrimination- capable Cs2LiYCl6:Ce (CLYC) scintillation detector combined with the rotational modulation collimator (RMC) technique for dual-particle imaging. Materials and Methods: In this study, a CLYC-based RMC system was designed based on Monte Carlo simulations, and a prototype was fabricated. Therein, a rotation control system was developed to rotate the RMC unit precisely, and a graphical user interface-based software was also developed to operate the data acquisition with RMC rotation. The RMC system was developed to allow combining various types of collimator masks and detectors interchangeably, making the imaging system more versatile for various applications and conditions. Results and Discussion: Operational performance of the fabricated system was studied by checking the accuracy and precision of the collimator rotation and obtaining modulation patterns from a gamma-ray source repeatedly. Conclusion: The prototype RMC system showed reliability in its mechanical properties and reproducibility in the acquisition of modulation patterns, and it will be further investigated for its dual-particle imaging capability with various complex radioactive source conditions.

Background: Boron Neutron Capture Therapy (BNCT) is a new radiation therapy. In BNCT, there exists some very critical problems that should be solved. One of the severest problems is that the treatment effect cannot be known during BNCT in real time. We are now developing a SPECT (single photon emission computed tomography) system (BNCT-SPECT), with a cadmium telluride (CdTe) semiconductor detector. BNCT-SPECT can obtain the BNCT treatment effect by measuring 478 keV gamma-rays emitted from the excited state of 7Li nucleus created by 10B(n,α) 7Li reaction. In the previous studies, we investigated the feasibility of the BNCTSPECT system. As a result, the S/N ratio did not meet the criterion of S/N > 1 because deterioration of the S/N ratio occurred caused by the influence of Compton scattering especially due to capture gamma-rays of hydrogen. Materials and Methods: We thus produced an arrayed detector with two CdTe crystals to test cross talk phenomenon and to examine an anti-coincidence detection possibility. For more precise analysis for the anti-coincidence detection, we designed and made a collimator having a similar performance to the real BNCT-SPECT. Results and discussion: We carried out experiments with the collimator to examine the effect of cross talk of scattering gamma-rays between CdTe elements more practically. As a result of measurement the coincidence events were successfully extracted. Conclusion: We are now planning to carry out evaluation of coincidence rate from the measurement and comparison of it with the numerical calculations.