• The Korean Journal of Pain
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• v.27 no.2
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• pp.145-151
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• 2014

Background: The physician's hands are close to the X-ray field in C-arm fluoroscopy-guided pain interventions. We prospectively investigated the radiation attenuation of Proguard RR-2 gloves. Methods: In 100 cases, the effective doses (EDs) of two dosimeters without a radiation-reducing glove were collected. EDs from the two dosimeters-one dosimeter wrapped with a glove and the other dosimeter without a glove-were also measured at the side of the table (Group 1, 140 cases) and at a location 20 cm away from the side of the table (Group 2, 120 cases). Mean differences such as age, height, weight, radiation absorbed dose (RAD), exposure time, ED, and ratio of EDs were analyzed. Results: In the EDs of two dosimeters without gloves, there were no significant differences ($39.0{\pm}36.3{\mu}Sv$ vs. $38.8{\pm}36.4{\mu}Sv$) (P = 0.578). The RAD ($192.0{\pm}182.0radcm^2$) in Group 2 was higher than that ($132.3{\pm}103.5radcm^2$) in Group 1 (P = 0.002). The ED ($33.3{\pm}30.9{\mu}Sv$) of the dosimeter without a glove in Group 1 was higher than that ($12.3{\pm}8.8{\mu}Sv$) in Group 2 (P < 0.001). The ED ($24.4{\pm}22.4{\mu}Sv$) of the dosimeter wrapped with a glove in Group 1 was higher than that ($9.2{\pm}6.8{\mu}Sv$) in Group 2 (P < 0.001). No significant differences were noted in the ratio of EDs ($73.5{\pm}6.7%$ vs. $74.2{\pm}9.3%$, P = 0.469) between Group 1 and Group 2. Conclusions: Proguard RR-2 gloves have a radiation attenuation effect of 25.8-26.5%. The radiation attenuation is not significantly different by intensity of scatter radiation or the different RADs of C-arm fluoroscopy.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.1 no.2
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• pp.130-136
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• 2015

We evaluate the influence of MR contrast agent on positron emission tomography (PET) image using phantom, animal and human studies. Phantom consisted of 15 solutions with the mixture of various concentrations of Gd-based MR contrast agent and fixed activity of [$^{18}F$]FDG. Animal study was performed using rabbit and two kinds of MR contrast agents. After injecting contrast agent, CT or MRI scanning was performed at 1, 2, 5, 10, and 20 minutes. PET image was obtained using clinical PET/CT scan, and attenuation correction was performed using the all CT images. The values of HU, PET activity and MRI intensity were obtained from ROIs in each phantom and organ regions. In clinical study, patients (n=20) with breast cancer underwent sequential acquisitions of early [$^{18}F$]FDG PET/CT, MRI and delayed PET/CT. In phantom study, as the concentration increased, the CT attenuation and PET activity also increased. However, there was no relationship between the PET activity and the concentration in the clinical dose range of contrast agent. In animal study, change of PET activity was not significant at all time point of CT scan both MR contrast agents. There was no significant change of HU between early and delayed CT, except for kidney. Early and delayed SUV in tumor and liver showed significant increase and decrease, respectively (P<0.05). Under the condition of most clinical study (< 0.2 mM), MR contrast agent did not influence on PET image quantitation.

• Journal of Radiation Industry
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• v.12 no.4
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• pp.267-276
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• 2018

A Hoffman 3D Brain Phantom was used to evaluate two PET/CT scanners, BIO_40 and D_690, according to the radiation dose of CT (low, medium and high) at a fixed kilo-voltage-peak (kVp) with the tube current(mA) varied in 17~20 stages(Bio_40 PET/CT scanner: the tube voltage was fixed to 120 kVp, the effective tube current(mAs) was increased from 33 mAs to 190 mAs in 10 mAs increments, D_690 PET/CT scanner: the tube voltage was fixed to 140 kVp, tube current(mA) was increased from 10 mAs to 200 mAs in 10 mAs increments). After obtaining the PET image, an attenuation correction was conducted based on the attenuation map, which led to an analysis of the difference in the image. First, the ratio of white to gray matter for each scanner was examined by comparing the coefficient of variation (CV) depending on the average ratio. In addition, a blind test was carried out to evaluate the image. According to the study results, the BIO_40 and D_690 scanners showed a <1% change in CV value due to the tube current conversion. The change in the coefficients of white and gray matter showed that the Z value was negative for both scanners, indicating that the coefficient of gray matter was higher than that of white matter. Moreover, no difference was observed when the images were compared in a blind test.

• Journal of radiological science and technology
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• v.44 no.4
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• pp.343-350
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• 2021

3D printing technology is an additive manufacturing technology produced through 3D scanning or modeling method. This technology can be produced in a short time without mold, which has recently been applied in earnest in various fields. In the medical field, 3D printing technology is used in various fields of radiology and radiation therapy, but related research is insufficient in the field of nuclear medicine. In this study, we compare the characteristics of traditional nuclear medicine phantom with 3D printing technology and evaluate its applicability in clinical trials. We manufactured the same size phantom of poly methyl meta acrylate(PMMA) and acrylonitrile butadiene styrene(ABS) based on the aluminum step wedge. We used BrightView XCT(Philips Health Care, Cleveland, USA) SPECT/CT. We acquired 60 min list mode for Aluminum, PMMA and ABS phantoms using Rectangular Flood Phantom (Biodex, New York, USA) ^99mTcO₄ 3 mCi(111 MBq), 6 mCi (222MBq) and ⁵⁷Co Flood phantom(adq, New Hampshire, USA). For the analysis of acquired images, the region of interest(ROI) were drawn and evaluated step by step for each phantom. Depending on the type of radioisotope and radiation dose, the counts of the ABS phantom was similar to that of the PMMA phantom. And as the step thickness increased, the counts decreased linearly. When comparing the linear attenuation coefficient of Aluminum, PMMA and ABS phantom, the linear attenuation coefficient of the aluminium phantom was higher than that of the others, and the PMMA and ABS phantom had similar the linear attenuation coefficient. Based on ABS phantom manufactured by 3D printing technology, as the thickness of the PMMA phantom increased, the counts and linear attenuation coefficient decreased linearly. It has been confirmed that ABS phantom is applicable in the clinical field of nuclear medicine. If the calibration factor is applied through further research, it is believed that practical application will be possible.

• Progress in Medical Physics
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• v.8 no.1
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• pp.37-45
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• 1997

The present work is determine to the dose distribution reduced by the insertion of a shielded into a vaginal cylinder around a $\^$60/CO source in brachytherapy, and to the source calibration. It was investigated by measuring the relative dose around a 2.5cm diameter shielded vaginal cylinder in a polystyrene phantom by use of a ionization chamber. Measurements were made with the cylinder unshielded and 0.55cm thick 90$^{\circ}C$ lead shields inserted. Also, the dose distribution compared measurement value with calculation value according to the device manufacturer and the multiple-divided dose tables. A reduction in dose was observed on the unshielded side of the cylinder which increased with distance from the source and it does 4.4％ within 1cm from the surface of the cylinder. On the shielded side of the cylinder, the dose at the surface is reduced to about 20.4％ of its value without the shield. The effective attenuation factor entered for the 90$^{\circ}C$ lead shielded cylinder was average 0.2 in a $\^$60/CO moving source. In comparision with the dose calculation mathods, the multiple-divided dose tables are difference less than ${\pm}$4.1％ with measured data in a $\^$60/Co source.

• Nuclear Medicine and Molecular Imaging
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• v.40 no.3
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• pp.169-176
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• 2006

Purpose: According to the development of CT scanner in PET/CT system, the role of CT unit as a diagnostic tool has been more important. To improve the diagnostic ability of CT scanner, it is a key aspect that CT scanning has to be performed with high dose energy and intravenous (IV) contrast. So we investigated the effect of IV contrast media on the maximum SUV (maxSUV) of normal tissues and pathologic lesions using PET/CT scanner with high dose CT scanning. Materials & Methods: The study enrolled 13 patients who required PET/CT evaluation. At first, the patients were performed whole body non-contrast CT (NCCT-120 kVp, 130 mAs) scan. Then contrast enhanced CT (CECT) scan was performed immediately. Finally PET scan was followed. The PET omission data were reconstructed twice, once with the NCCT and again with the CECT. We measured the maxSUV of 10 different body regions that were considered as normal in ail patients. Also pathologic lesions were investigated. Results: There were not seen focal artifacts in PET images based on CT with IV contrast agent. Firstly, 130 normal regions in 13 patients were evaluated. The maxSUV was significantly different between two PET images (p<0.00)). The maxSUV was $1.1{\pm}0.5$ in PET images with CECT-corrected attenuation and $1.0{\pm}0.5$ in PET images with NCCI-corrected attenuation. The limit of agreement was $0.1{\pm}0.3$ in Bland-Altman analysis. Especially there were significant differences in 6 of 10 regions, apex and base of the right lung, ascending aorta, segment 6 & segment 8 of the liver and spleen (p<0.05). Secondly, 39 pathologic lesions were evaluated. The maxSUV was significantly different between two PET images (p<0.001). The maxSUV was $4.7{\pm}2.0$ in PET images with CECT-corrected attenuation and $4.4{\pm}2.0$ in PET images with NCCT-corrected attenuation. The limit of agreement was $0.4{\pm}0.8$ in Bland-Altman analysis. Conclusion: Although there were increases of maxSUVs in the PET images based on CT with IV contrast agent, it was very narrow in the range of limit of agreement. So there was no significant effect to clinical interpretation for PET images that were corrected attenuation with high dose CT using IV contrast.

• Journal of the Korean Society of Radiology
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• v.17 no.3
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• pp.449-457
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• 2023

Shielding for reducing exposure dose can make the diagnosis limited. The purpose of this study is to increase the efficiency of radiation protection and minimize the loss of image information by producing the shielding made of the water and the contrast medium which has different proportion and finding out the ideal proportion of them. Each shielding materials were made of water and water-soluble iodine contrast medium with the different proportion. The attenuation rate of absorbed dose was evaluated by the shielding materials in the plastic contents for measuring the efficiency of the radiation protection. As a result, the higher ratio of the contrast medium, the more efficient it is for radiation attenuation. The anatomical structure was observed most properly in case of the solution with 20 ml of the contrast medium and most difficultly in case of more than 60 ml of the contrast medium. In case of the signal intensity between skeleton and gas, the difference of average value had a significant as p < 0.001. Shielding with contrast medium attenuates less than the conventional shielding but in the examination for the sensitive part to radiation, it can be used to minimize the loss of the image information and reduce the exposure dose.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.1
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• pp.55-61
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• 2015

When a radiation detector is applied to the measurement of the radioactivity of high-level of radioactive materials or the rapid response to the nuclear accident, several collimators with the different inner radii should be prepared according to the level of dose rate. This makes the in-situ measurement impractical, because of the heavy weight of the collimator. In this study, an IRIS collimator was developed so as to have a function of controlling the inner radius, with the same method used in optical camera, to vary the attenuation ratio of radiation. The shutter was made to have the double tungsten layers with different phase angles to prevent the radiation from penetrating owing to the mechanical tolerance. The performance evaluation through the MCNP code was conducted by calculating the attenuation ratio according to the inner radius of the collimator. The attenuation ratio was marked on the outer scale ring of the collimator. It is expected that when a radiation detector with the IRIS collimator is used for the in-situ measurement, it can change the attenuation ratio of the incident photon to the detector without replacing the collimator.

• The Journal of Korean Society for Radiation Therapy
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• v.23 no.1
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• pp.41-49
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• 2011

Purpose: This study is designed to investigate radiotherapic valuation of Paraffin Wax, which is newly formed for this study and generally utilized in dentistry, and Mouth Piece and Putty impression, which are commonly used in radiotherapy, for oral cavity as a compensator. Materials and Methods: Each compensator was formed by $10{\times}10{\times}1cm$ and measured radiation dose attenuation ratio with reference of water phantom which is made of tissue-equivalent materials. Two patients with oral cancer underwent DRR (Digitally Reconstructed Radiogrph) of Offline Review Program of Aria System and Portal vision for 5 times for each material to evaluate reproducibility by each filling materials. Moreover, MU (monitor unit) changes by dose absorption were considered in the case of inevitable implication of an filling materials in the range for radiotherapy. Results: Radiation dose attenuation ratios were shown -0.7~+3.7% for Mouth Piece, +0.21~+0.39% for Paraffin Wax and -2.71~-1.76% for Putty impression. Error ranges of reproducibility of positions were measured ${\pm}3mm$ for Mouth Piece, ${\pm}2mm$ for Paraffin Wax and ${\pm}2mm$ mm for Putty impression. Difference of prescription MU from dose absorption with an filling material increased +7.8% (250 MU) in Putty impression and -0.9% (230 MU) in Paraffin Wax as converted into a percentage from the standard phantom, Water 232 MU. Conclusion: Dose reduction of boundary between cavity and tissue was observed for Mouth Piece. Mouth Piece also had low reproducibility of positions as it had no reflection of anatomy of oral cavity even though it was a proper material to separate Maxilla and Mandible during therapy. On the other hand, Putty impression was a suitable material to correctly re-position oral cavity as before. However, it risked normal tissues getting unnecessary over irradiation and it caused radiation dose decrease by -2.5% for 1cm volume in comparison of it of water phantom. Dose reduction in Paraffin Wax, Fat Tissue-Equivalent Material, was smaller than other impressions and position reproducibility of it was remarkable as it was possible to make an anatomy reflected impression. It was also well fitted to oral cavity to transfer radiation dose planned in radiotherapy. Thus, Paraffin Wax will be an ideal material in radiotherapy for patients with oral cancer.

• Progress in Medical Physics
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• v.17 no.3
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• pp.173-178
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• 2006

The purpose of this study was to evaluate the radiation dose for clinical PET/CT protocols in clinical environments using Alderson phantom and TLDs. Radiation doses were evaluated for both Philips GEMINI 16 slice PET/CT system and GE DSTe 16 slice PET/CT system. Specific organ doses with $^{137}Cs$ transmission scan, high quality CT scan and topogram in philips GEMINI PET/CT system were measured. Specific organ doses with CT scan for attenuation map, CT scan for diagnosis and topogram in GE DSTe PET/CT system were also measured. The organs were selected based on ICRP60 recommendation. The TLDs used for measurements were selected for within an accuracy of ${\pm}5%$ and calibrated in 10 MV X-ray radiation field. The effective doses for $^{137}Cs$ transmission scan, high qualify scan, and topogram in Philips GEMINI PET/CT system were $0.14{\pm}0.950,\;29.49{\pm}1.508\;and\;0.72{\pm}0.032mSv$ respectively. The effective doses for CT scan to make attenuation map, CT scan to diagnose and topogram in GE DSTe PET/CT system were $20.06{\pm}1.003,\;24.83{\pm}0.805\;and\;0.27{\pm}0.008mSv$ respectively. We evaluated the total effective dose by adding effective dose for PET Image. The total PET/CT doses for Philips GEMINI PET/CT (Topogram+$^{137}Cs$ transmission scan+PET, Topogram+high qualify CT+PET) and GE DSTe PET/CT (Topogram +CT for attenuation map+ PET, Topogram+diagnostic CT+ PET) are $7.65{\pm}0.951,\;37.00{\pm}1.508,\;27.12{\pm}1.003\;and\;31.89{\pm}0.805mSv$ respectively. Further study may be needed to be peformed to find optimal PET/CT acquisition protocols for reducing the patient exposure with good image qualify.