• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.2
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• pp.65-71
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• 2011

Purpose: The recently adopted multiple confocal SPECT SYSTEM (hereinafter called IQ SPECT$^{TM}$) has a high difference from the conventional myocardial perfusion SPECT in the collimator form, image capture method, and image reconstruction method. This study was conducted to compare this novice equipment with the conventional one to design a protocol meeting the IQ SPECT, and also determine the characteristics and usefulness of IQ SPECT. Materials and Methods: 1. For the objects of LEHR (Low energy high resolution) collimator and Multiple confocal collimator, $^{99m}Tc$ 37MBq was put in the acrylic dish then each sensitivity ($cpm/{\mu}Ci$) was measured at the distance of 5 cm, 10 cm, 20 cm, 30 cm, and 40 cm respectively. 2. Based on the sensitivity measure results, IQ SPECT Protocol was designed according to the conventional general myocardial SPECT, then respectively 278 kBq/mL, 7.4 kBq/mL, and 48 kBq/mL of $^{99m}Tc$ were injected into the myocardial and soft tissues and liver site by using the anthropomorphic torso phantom then the myocardial perfusion SPECT was run. 3. For the comparison of FWHMs (Full Width at Half Maximum) resulted from the image reconstruction of LEHR collimator, the FWHMs (mm) were measured with only algorithms changed, in the case of the FBP (Filtered Back projection) method- a reconstruction method of conventional myocardial perfusion SPECT, and the 3D OSEM (Ordered subsets expectation maximization) method of IQ SPECT, by using $^{99m}Tc$ Line source. Results: 1. The values of IQ SPECT collimator sensitivity ($cpm/{\mu}Ci$) were 302, 382, 655, 816, 1178, and those of LEHR collimator were measured as 204, 204, 202, 201, 198, both at the distance of 5 cm, 10 cm, 20 cm, 30 cm, and 40 cm respectively. It was found the difference of sensitivity increases up to 4 times at the distance of 30 cm in the cases of IQ SPECT and LEHR. 2. The myocardial perfusion SPECT Protocol was designed according to the geometric characteristics of IQ SPECT based on the sensitivity results, then the phantom test for the aforesaid protocol was conducted. As a result, it was found the examination time can be reduced 1/4 compared to the past. 3. In the comparison of FWHMs according to the reconstructed algorithm in the FBP method and 3D OSEM method followed after the SEPCT test using a LEHR collimator, the result was obtained that FWHM rose around twice in the 3D OSEM method. Conclusion : The IQ SPECT uses the Multiple confocal collimator for the myocardial perfusion SPECT to enhance the sensitivity and also reduces examination time and contributes to improvement of visual screen quality through the myocardial-specific geometric image capture method and image reconstruction method. Due to such benefits, it is expected patients will receive more comfortable and more accurate examinations and it is considered a further study is required using additional clinical materials.

• The Journal of Korean Society for Radiation Therapy
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• v.26 no.2
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• pp.337-343
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• 2014

Purpose : The aim of this study is to evaluate unwanted scattered dose to ovary by scattering and leakage generated from treatment fields of Tomotherapy for childbearing woman with breast cancer. Materials and Methods : The radiation treatments plans for left breast cancer were established using Tomotherapy planning system (Tomotherapy, Inc, USA). They were generated by using helical and direct Tomotherapy methods for comparison. The CT images for the planning were scanned with 2.5 mm slice thickness using anthropomorphic phantom (Alderson-Rando phantom, The Phantom Laboratory, USA). The measurement points for the ovary dose were determined at the points laterally 30 cm apart from mid-point of treatment field of the pelvis. The measurements were repeated five times and averaged using glass dosimeters (1.5 mm diameter and 12 mm of length) equipped with low-energy correction filter. The measures dose values were also converted to Organ Equivalent Dose (OED) by the linear exponential dose-response model. Results : Scattered doses of ovary which were measured based on two methods of Tomo helical and Tomo direct showed average of $64.94{\pm}0.84mGy$ and $37.64{\pm}1.20mGy$ in left ovary part and average of $64.38{\pm}1.85mGy$ and $32.96{\pm}1.11mGy$ in right ovary part. This showed when executing Tomotherapy, measured scattered dose of Tomo Helical method which has relatively greater monitor units (MUs) and longer irradiation time are approximately 1.8 times higher than Tomo direct method. Conclusion : Scattered dose of left and right ovary of childbearing women is lower than ICRP recommended does which is not seriously worried level against the infertility and secondary cancer occurrence. However, as breast cancer occurrence ages become younger in the future and radiation therapy using high-precision image guidance equipment like Tomotherapy is developed, clinical follow-up studies about the ovary dose of childbearing women patients would be more required.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.1
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• pp.127-132
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• 2010

Purpose: Because of limitation of image acquisition method and acquisition time, scatter correction cannot perform easily in SPECT study. But in our hospital, could provide to clinic doctor of scatter corrected images, through introduction of new generation gamma camera has function of simple scatter correction. Taking this opportunity, we will compare scatter corrected and non-scatter corrected image from image quality of point of view. Materials and Methods: We acquisite the 'Hoffman brain phantom' SPECT image and '1mm line phantom' SPECT image, each 18 times, with GE Infinia Hawkeye 4, SPECT-CT gamma camera. At first, we calculated each contrast from axial slice of scatter corrected and non-scatter corrected SPECT image of 'Hoffman brain phantom'. and next, calculated each FWHM of horizontal and vertical from axial slice of scatter corrected and non-scatter corrected SPECT image of '1mm line phantom'. After then, we attempted T test analysis with SAS program on data, contrast and resolution value of scatter corrected and non-scatter corrected image. Results: The contrast of scatter corrected image, elevated from 0.3979 to 0.3509. And the resolution of scatter corrected image, elevated from 3.4822 to 3.6375. p value were 0.0097 in contrast and <0.0001 in resolution. We knew the fact that do improve of contrast and resolution through scatter correction. Conclusion: We got the improved SPECT image through simple and easy way, scatter correct. We will expect to provide improved images, from contrast and resolution point of view. to our clinic doctor.

• Journal of radiological science and technology
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• v.34 no.1
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• pp.51-58
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• 2011

The aim of the study is to analyze the dose delivery error depending on the depth variation according to target positions and arc trajectories by comparing the simulated treatment planning with the actual dose delivery in conformal arc therapy. We simulated the conformal arc treatment planning with the three target positions (center, 2.5 cm, and 5 cm in the phantom). For the experiments, IMRT body phantom (I’mRT Phantom, Wellhofer Dosimetry, Germany) was used for treatment planning with CT (Computed Tomography, Light speed 16, GE, USA). The simulated treatment plans were established by three different target positions using treatment planning system (Eclipse, ver. 6.5, VMS, Palo Alto, USA). The radiochromic film (Gafchromic EBT2, ISP, Wayne, USA) and dose analysis software (OmniPro-IMRT, ver. 1.4, Wellhofer Dosimetry, Germany) were used for the measurement of the planned arc delivery using 6 MV photon beam from linear accelerator (CL21EX, VMS, Palo Alto, USA). Gamma index (DD: 3%, DTA: 2 mm) histogram and dose profile were evaluated for a quantitative analysis. The dose distributions surrounded by targets were also compared with each plans and measurements by conformity index (CI), and homogeneity index (HI). The area covered by 100% isodose line was compared to the whole target area. The results for the 5 cm-shifted target plan show that 23.8%, 35.6%, and 37% for multiple conformal arc therapy (MCAT), single conformal arc therapy (SCAT), and multiple static beam therapy, respectively. In the 2.5 cm-shifted target plan, it was shown that 61%, 21.5%, and 14.2%, while in case of center-located target, 70.5%, 14.1%, and 36.3% for MCAT, SCAT, and multiple static beam therapy, respectively. The values were resulted by most superior in the MCAT, except the case of the 5 cm-shifted target. In the analysis of gamma index histogram, it was resulted of 37.1, 27.3, 29.2 in the SCAT, while 9.2, 8.4, 10.3 in the MCAT, for the target positions of center, shifted 2.5 cm and 5 cm, respectively. The fail proportions of the SCAT were 2.8 to 4 times as compared to those of the MCAT. In conclusion, dose delivery error could be occurred depending on the target positions and arc trajectories. Hence, if the target were located in the biased position, the accurate dose delivery could be performed through the optimization of depth according to arc trajectory.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2003.09a
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• pp.63-63
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• 2003

Purpose: Planning target volume (PTV) for tumors in abdomen or thorax includes enough margin for breathing-related movement of tumor volumes during treatment. We developed a simple and handy method, which can reduce PTV margins in patients with moving tumors, respiratory motion reduction device system (RMRDs). Materials and Methods: The patients clinical database was structured for moving tumor patients and patient setup error measurement and immobilization device effects were investigated. The system is composed of the respiratory motion reduction device utilized in prone position and abdominal presser (strip device) utilized in the supine position, moving phantom and the analysis program, which enables the analysis on patients setup reproducibility. It was tested for analyzing the diaphragm movement and CT volume differences from patients with RMRDs, the magnitude of PTV margin was determined and dose volume histogram (DVH) was computed using a treatment planning software. Dose to normal tissue between patients with RMRDs and without RMRDs was analyzed by comparing the fraction of the normal liver receiving to 50% of the isocenter dose(TD50). Results: In case of utilizing RMRDs, which was personally developed in our hospital, the value was reduced to $5pm1.4 mm$, and in case of which the belt immobilization device was utilized, the value was reduced to 3$pm$0.9 mm. Also in case of which the strip device was utilized, the value was proven to reduce to $4pm.3 mm$0. As a result of analyzing the TD50 is irradiated in DVH according to the radiation treatment planning, the usage of the respiratory motion reduction device can create the reduce of 30% to the maximum. Also by obtaining the digital image, the function of comparison between the standard image, automated external contour subtraction, and etc were utilized to develop patients setup reproducibility analysis program that can evaluate the change in the patients setup. Conclusion: Internal organ motion due to breathing can be reduced using RMRDs, which is simple and easy to use in clinical setting. It can reduce the organ motion-related PTV margin, thereby decrease volume of the irradiated normal tissue.

• The Journal of the Korea Contents Association
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• v.14 no.8
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• pp.233-242
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• 2014

The purpose of this study is to compare the reduction of the dose radioactivity by CARE kV with that of the Bismuth shielding. First, CT was performed with transparent materials, including a Bismuth shielder which is a well-known material for decreasing the dose of radiation. Moreover, we have estimated and compared the affects of the reduction of dose on eye lens, thyroid, breast and genitals. These steps aim to compare reactions with and without the application of the Rando phantom with PLD as well as with CARE kV or not. As a result, during the Brain angio scan, the dose of CARE kV set inspection test methods showed the least dose. Depending on whether we use CARE kV, which showed the effect of dose reduction by 63%. During the Carotid angio scan, the dose was increased by 13% by how to set CARE kV+Bismuth. During the Cardiac angio scan, which showed the effect of dose reduction by 31% by how to set CARE kV+Bismuth. During the Lower extremity angio scan, the dose was measured least by how to set up the whole Bismuth. Compared with CARE kV set of test methods, which showed the effect of dose reduction by 9%.

• Journal of radiological science and technology
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• v.42 no.6
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• pp.447-454
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• 2019

In order to improve and supplement the shielding method for electron beam treatment, we designed a patient-specific shielding method using a 3D printer, and evaluated the usefulness by comparing and analyzing the distribution of electron beam doses to adjacent organs. In order to treat 5 cm sized superficial tumors around the lens, a CT Simulator was used to scan the Alderson Rando phantom and the DICOM file was converted into an STL file. The converted STL file was used to design a patient-specific shield and mold that matched the body surface contour of the treatment site. The thickness of the shield was 1 cm and 1.5 cm, and the mold was printed using a 3D printer, and the patient customized shielding block (PCSB) was fabricated with a cerrobend alloy with a thickness of 1 cm and 1.5 cm. The dosimetry was performed by attaching an EBT3 film on the surface of the Alderson Rando phantom eyelid and measuring the dose of 6, 9, and 12 MeV electron beams on the film using four shielding methods. Shielding rates were 83.89%, 87.14%, 87.39% at 6, 9, and 12 MeV without shielding, 1 cm (92.04%, 87.48%, 86.49%), 1.5 cm (91.13%, 91.88% with PSCB), 92.66%) The shielding rate was measured as 1 cm (90.7%, 92.23%, 88.08%) and 1.5 cm (88.31%, 90.66%, 91.81%) when the shielding block and the patient-specific shield were used together. PCSB fabrication improves shielding efficiency over conventional shielding methods. Therefore, PSCB may be useful for clinical application.

• Journal of Magnetics
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• v.21 no.2
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• pp.293-297
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• 2016

For mastectomy patients, sufficient doses of radiation should be delivered to the surface of the chest wall to prevent recurrence. A bolus is used to increase the surface dose on the chest wall, whereby the surface dose is confirmed with the use of a virtual bolus during the computerized treatment-planning process. The purpose of this study is an examination of the difference between the dose of the computerized treatment plan and the dose that is measured on the bolus. Part of the left breast of an Anderson Rando phantom was removed, followed by the attainment of computed tomography (CT) images that were used as the basis for computerized treatment plans that were established with no bolus, a 3 mm-thick bolus, a 5 mm-thick bolus, and a 10 mm-thick bolus. For the computerized treatment plan, a prescribed dose regimen was dispensed daily and planning target volume (PTV) coverage was applied according to the RTOG 1304 guidelines. Using each of the established computerized treatment plans, chest-wall doses of 5 points were measured; this chest-wall dose was used as the standard for the analysis of this study, while the level of significance was set at P < 0.05. The measurement of the chest-wall dose with no bolus is 1.6 % to 10.3 % higher, and the differences of the minimum average and the maximum average of the five measurement points are -13.8 and -1.9, respectively (P < 0.05); however, when the bolus was used, the dosage was measured as 3.7 % to 9.2 % lower, and the differences of the minimum average and the maximum average are 7.4 and 9.0, -1.2 and 17.4, and 8.1 and 19.8 for 3 mm, 5 mm, and 10 mm, respectively (P < 0.05). As the thickness of the bolus is increased, the differences of the average surface dose are further increased. There are a variety of factors that affect the surface dose on the chest wall during post-mastectomy radiation therapy, for which verification is required; in particular, a consideration of the appropriate thickness and the number of uses when a bolus is used, and which has the greatest effect on the surface dose on the chest wall, is considered necessary.

• Journal of radiological science and technology
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• v.42 no.3
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• pp.217-222
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• 2019

The purpose of this study is to evaluate the dose distribution by gantry rotation and MLC moving speed on treatment planning system(TPS) and linear accelerator. The dose analyzer phantom(Delta 4) was scanned by CT simulator for treatment planning. The planning target volumes(PTVs) of prostate and pancreas was prescribed 6,500 cGy, 5,000 cGy on VMAT(Volumetric Modulated Arc Therapy) by TPS while MLC speed changed. The analyzer phantom was irradiated linear accelerator using by planned parameters. Dose distribution of PTVs were evaluated by the homogeneity index, conformity index, dose volume histogram of organ at risk(rectum, bladder, spinal cord, kidney). And irradiated dose analysis were evaluated dose distribution and conformity by gamma index. The PTV dose of pancreas was 4,993 cGy during 0.1 cm/deg leaf and gantry that was the most closest prescribed dose(5,000 cGy). The dose of spinal cord, left kidney, and right kidney were accessed the lowest during 0.1 cm/deg, 1.5 cm/deg, 0.3 cm/deg. The PTV dose of prostate was 6,466 cGy during 0.1 cm/deg leaf and gantry that was the most closest prescribed dose(6,500 cGy). The dose of bladder and rectum were accessed the lowest during 0.3 cm/deg, 2.0 cm/deg. For gamma index, pancreas and prostate were analyzed the lowest error 100% at 0.8, 1.0 cm/deg and 99.6% at 0.3, 0.5 cm/deg. We should used the optimal leaf speed according to the gantry rotation if the treatment cases are performed VMAT.

• Progress in Medical Physics
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• v.23 no.3
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• pp.145-153
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• 2012

In this study, we quantify the residual motion artifact in 4D-CT scan using the dynamic lung phantom which could simulate respiratory target motion and suggest a simple one-dimension theoretical model to explain and characterize the source of motion artifacts in 4DCT scanning. We set-up regular 1D sine motion and adjusted three level of amplitude (10, 20, 30 mm) with fixed period (4s). The 4DCT scans are acquired in helical mode and phase information provided by the belt type respiratory monitoring system. The images were sorted into ten phase bins ranging from 0% to 90%. The reconstructed images were subsequently imported into the Treatment Planning System (CorePLAN, SC&J) for target delineation using a fixed contour window and dimensions of the three targets are measured along the direction of motion. Target dimension of each phase image have same changing trend. The error is minimum at 50% phase in all case (10, 20, 30 mm) and we found that ${\Delta}S$ (target dimension change) of 10, 20 and 30 mm amplitude were 0 (0%), 0.1 (5%), 0.1 (5%) cm respectively compare to the static image of target diameter (2 cm). while the error is maximum at 30% and 80% phase ${\Delta}S$ of 10, 20 and 30 mm amplitude were 0.2 (10%), 0.7 (35%), 0.9 (45%) cm respectively. Based on these result, we try to analysis the residual motion artifact in 4D-CT scan using a simple one-dimension theoretical model and also we developed a simulation program. Our results explain the effect of residual motion on each phase target displacement and also shown that residual motion artifact was affected that the target velocity at each phase. In this study, we focus on provides a more intuitive understanding about the residual motion artifact and try to explain the relationship motion parameters of the scanner, treatment couch and tumor. In conclusion, our results could help to decide the appropriate reconstruction phase and CT parameters which reduce the residual motion artifact in 4DCT.