• Journal of radiological science and technology
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• v.43 no.1
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• pp.9-14
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• 2020

Commercial plate bolus is generally used for treatment of surface tumor and required surface dose. We fabricated 3D-printed bolus by using 3D printing technology and usability of 3D-printed bolus was evaluated. RT-structure of contoured plate bolus in the TPS was exported to DICOM files and converted to STL file by using converting program. The 3D-printed bolus was manufactured with rubber-like translucent materials using a 3D printer. The dose distribution calculated in the TPS and compared the characteristics of the plate bolus and the 3D printed bolus. The absolute dose was measured inserting an ion chamber to the depth of 5 cm and 10 cm from the surface of the blue water phantom. HU and ED were measured to compare the material characteristics. 100% dose was distributed at Dmax of 1.5 cm below the surface when was applied without bolus. When the plate bolus and 3D-plate bolus were applied, dose distributed at 0.9 cm and 0.8 cm below the surface of the bolus. After the comparative analysis of the radiation dose at the reference depth, differences in radiation dose of 0.1 ~ 0.3% were found, but there was no difference dose. The usability of the 3D-printed bolus was thus confirmed and it is considered that the 3D-printed bolus can be applied in radiation therapy.

• Nuclear Engineering and Technology
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• v.52 no.10
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• pp.2410-2414
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• 2020

Heavy ions have a high potential for destroying deep tumors that carry the highest dose at the peak of Bragg. The peak caused by a single-energy carbon beam is too narrow, which requires special measures for improvement. Here, carbon-12 (¹²C) ion with different energies has been used as a source for calculating the dose distribution in the water phantom, soft tissue and bone by the code of Monte Carlobased FLUKA code. By increasing the energy of the initial beam, the amount of absorbed dose at Bragg peak in all three targets decreased, but the trend for this reduction was less severe in bone. While the maximum absorbed dose per bone-mass unit in energy of 200 MeV/u was about 30% less than the maximum absorbed dose per unit mass of water or soft tissue, it was merely 2.4% less than soft tissue in 400 MeV/u. The simulation result showed a good agreement with experimental data at GSI Darmstadt facility of biophysics group by 0.15 cm average accuracy in Bragg peak positioning. From 200 to 400 MeV/u incident energy, the Bragg peak location increased about 18 cm in soft tissue. Correspondingly, the bone and soft tissue revealed a reduction dose ratio by 2.9 and 1.9. Induced neutrons did not contribute more than 1.8% to the total energy deposited in the water phantom. Also during ¹²C ion bombardment, secondary fragments showed 76% and 24% of primary 200 and 400 MeV/u, respectively, were present at the Bragg-peak position. The combined treatment of carbon ions with neutron or electron beams may be more effective in local dose delivery and also treating malignant tumors.

• Radiation Oncology Journal
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• v.15 no.1
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• pp.65-69
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• 1997

Purpose : To obtain the actual dose distribution from measured data by doconvolution method using the measured ion chamber response function. Materials and Methods : The chamber response functions for 2 ionization chambers (diameter 5mm, 6.4mm) were measured. and dose Profiles were measured for $10{\times}20cm^2$ field size using two different detectors. The deconvolution of chamber response function from the measured data were performed for these Profiles. The same procedures were repeated for 4MV, 6MV and 1 SMV photon energies. Results : Different dose Profiles were obtained for the same field with the chambers which have the different response functions. Nearly the same results could be obtained with deconvolution for the profiles from various detectors. Conclusion : The effect of the chamber response function can be extracted by deconvolution method. Deconvolved dose profile using various ionization chambers gave better dose distributions. Technical improvements are needed for practical application.

• Journal of the Korean Society of Radiology
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• v.15 no.5
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• pp.723-730
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• 2021

This study tries to compare dose distribution between arc radiation therapy and Tomotherapy, which are main radiation therapy modalities. The subjects of this study are lung cancer patients. For planning target volume (PTV), a dose of 60.0 Gy was set as a basis. The PTVmean of Arc was 61.04 Gy, and that of Tomotherapy was 58.50 Gy. The total lung capacities of Arc and Tomotherapy were 3.0 Gy and 4.24 Gy, respectively. The mean heart doses of Arc and Tomotherapy were 0.13 and 0.34, respectively; the mean trachea dose of Arc and Tomotherapy were 1.35 and 2.58, respectively; the mean esophagus dose of Arc and Tomotherapy were 0.41 and 0.86, respectively; the mean spinal cord dose of Arc and Tomotherapy were 3.65 and 4.68, respectively. With regard to the appropriateness of therapeutic effect in DHV, both modalities seemed appropriate. Tomotherapy protected normal tissues better than Arc radiation therapy. In Tomotherapy, patients need to have treatment long in a limited space. If such a point is overcome, Tomotherapy is better. Otherwise, Arc radiation therapy can be applied. This study was conducted with treatment planning images. Therefore, the results of this study are different from actual treatment results. If more research is conducted to overcome the limitation, the effects of radiation therapy are expected to increase further.

• Radiation Oncology Journal
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• v.38 no.1
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• pp.60-67
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• 2020

Purpose: We performed three-dimensional (3D) dose reconstruction-based pretreatment verification to evaluate gamma analysis acceptance criteria in volumetric modulated arc therapy (VMAT) for prostate cancer. Materials and Methods: Pretreatment verification for 28 VMAT plans for prostate cancer was performed using the COMPASS system with a dolphin detector. The 3D reconstructed dose distribution of the treatment planning system calculation (TC) was compared with that of COMPASS independent calculation (CC) and COMPASS reconstruction from the dolphin detector measurement (CR). Gamma results (gamma failure rate and average gamma value [GFR and γAvg]) and dose-volume histogram (DVH) deviations, 98%, 2% and mean dose-volume difference (DD_98%, DD_2% and DD_mean), were evaluated. Gamma analyses were performed with two acceptance criteria, 2%/2 mm and 3%/3 mm. Results: The GFR in 2%/2 mm criteria were less than 8%, and those in 3%/3 mm criteria were less than 1% for all structures in comparisons between TC, CC, and CR. In the comparison between TC and CR, GFR and γAvg in 2%/2 mm criteria were significantly higher than those in 3%/3 mm criteria. The DVH deviations were within 2%, except for DD_mean (%) for rectum and bladder. Conclusions: The 3%/3 mm criteria were not strict enough to identify any discrepancies between planned and measured doses, and DVH deviations were less than 2% in most parameters. Therefore, gamma criteria of 2%/2 mm and DVH related parameters could be a useful tool for pretreatment verification for VMAT in prostate cancer.

• Journal of dental hygiene science
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• v.15 no.3
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• pp.254-258
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• 2015

To compare the stationary dental X-ray generator and the portable dental X-ray generator and to understand spatial radiation dose depended on locations by measuring spatial radiation dose of the portable dental X-ray generator. The researchers used an Ionization chamber to measure spatial radiation dose which was generated while applying X-ray radiation to real bone skull phantom with both portable and stationary dental X-ray generator. There were 4 measurement locations which were immediate anterior, right, left and posterior. Distance of measurement was 50 cm in every location and the recorded result is an average of two applications of X-ray radiation to the maxillary molar area under the condition of 70 kVp, 3 mA, 0.1 sec. Average spatial radiation dose of portable X-ray generator was $37.51{\mu}Sv$, much higher than that of stationary X-ray generator which was $10.77{\mu}Sv$ (p<0.001). The result of the spatial radiation dose of the portable X-ray generator showed a huge difference depending on types of units which varied from $17.77{\mu}Sv$ to $68.90{\mu}Sv$ (p<0.05), also depending on the measurement location, immediate anterior resulted in the highest radiation dose of $54.14{\mu}Sv$ and immediate right was the lowest of $13.60{\mu}Sv$. Immediate left and posterior, however, resulted in similar radiation dose which were $42.12{\mu}Sv$, $40.18{\mu}Sv$ (p<0.01). With this result, we claim that usage of portable dental X-ray generator should be restricted to patients who can't move and exposure to radiation should be minimized by wearing lead-apron.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.161-163
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• 1997

In this paper, a two-dimensional electron beam dose calculational algorithm implented for use in a two-dimensional radiation therapy planning system is described. The 2-D electron beam calculations have been in use clinically for a few decades. Our algorithm uses Age-diffusion model based int the Boltzman Transport Equation. Our implementation provides convenient user interface associated with electron beam therapy planning and displays radiation dose distribution according to different electron energy on patient images.

• The Journal of Korean Society for Radiation Therapy
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• v.1 no.1
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• pp.79-83
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• 1985

Carcinoma of the breast has been treated by surgery followed by irradiation of the chest wall and regional lymphatics treatment planning of the breast cancer is required that lung must be spared as much as possible. However megavoltage irradiation of the internal mammary chain results in high dose to underlying heart, esophagus and spinal cord. Electron beam can be used for the irradiation of the internal mammary chain instead of megavoltage beam. We studied dose distribution of single anterior electron field, compared with traditional treatment methods. 12 and 15MeV electron beam with bolus has good dose distribution to spare underlying lung tissue and other organs.

• Journal of the Korean Society of Radiology
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• v.18 no.6
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• pp.681-690
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• 2024

This study aimed to quantitatively analyze the effect of anode angle on the heel effect and image quality in digital radiography systems. For this purpose, two X-ray devices with anode angles of 12° and 16° (Accuray D6 and INNOVISION-SH) were used to compare the radiation dose distribution and the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in thoracic spine images, using a chest phantom under identical imaging conditions. In the radiation dose distribution study, it was observed that the device with a 12° anode angle showed more pronounced dose distribution non-uniformity, with a sharp decrease in dose from the cathode side to the anode side. In contrast, the 16° anode angle device exhibited a more gradual dose decrease and a more uniform distribution than the 12° device. It was confirmed that a smaller anode angle intensified the heel effect, causing the radiation intensity to be distributed unevenly. In the thoracic spine image analysis, it was found that, with an anode angle of 16°, the SNR and CNR improved when the chest phantom was placed in the standard orientation (T12 on the cathode side and T1 on the anode side). This suggests that the anode angle and patient positioning influence the effect of the heel effect on image quality. Compared to the reverse orientation (T1 on the cathode side and T12 on the anode side), the standard orientation provided superior image quality. Based on these findings, it is recommended that, in clinical practice, awareness of the anode angle and accurate differentiation between standard and reverse positioning during thoracic spine imaging with digital radiography systems can enhance image quality and improve diagnostic reliability.

• Journal of radiological science and technology
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• v.42 no.2
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• pp.137-143
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• 2019

The aim of this study was analyzed the setup error of breast cancer patients in intensity modulated radiation therapy(IMRT) with deep inspiration breath holding(DIBH) and was analyzed the dose distribution due to setup error. A total of 45 breast cancer cases were performed a retrospective clinical analysis of setup error. In addition, the re-treatment planning was carried by shifting the setup error from the isocenter at the treatment. Based on this, the dose distribution of PTV and OARs was compared and analyzed. The 3D error for small breast group and medium breast group and large breast group were 3.1 mm and 3.7 mm and 4.1 mm, respectively. The difference between the groups was statistically significant(P=0.003). DVH results showed HI, CI for the PTV difference between standard treatment plan and re-treatment plan of 14.4%, 4%. The difference in $D_5$ and $V_{20}$ of the ipsilateral lung was 5.6%, 13% respectively. The difference in $D_5$ and $V_5$ of the heart of right breast cancer patients was 6.8%, 8% respectively. The difference in $D_5$, $V_{20}$ of the heart of left breast cancer patients was 7.2%, 23.5% respectively. In this study, there was a significant association between breast size and significant setup error in breast cancer patients with DIBH. In addition, it was found that the dose distribution of the PTV and OARs varied according to the setup error.