• Progress in Medical Physics
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• v.28 no.2
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• pp.39-44
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• 2017

This study aims to analyze dose distribution and treatment time of endobronchial brachytherapy (EBBT) by changing the position step size of the dwell position. A solid water phantom and an intraluminal catheter were used in the treatment plan. The treatment plans were generated for 3, 5, 7, and 10 cm treatment lengths, respectively. For each treatment length, the source position step sizes were set as 2.5, 5, and 10 mm. Three reference points were set 1 cm away from the central axis of the catheter, along the axis, for uniform dose distribution. Volumetric dose distribution was calculated to evaluate the dosimetric effect. The total radiation delivery time and total dwell time were estimated for treatment efficiency, which were increased with position step sizes. At half-life time, the differences between the position step sizes in the total radiation delivery time were 18.1, 15.4, 18.0, and 24.0 s for 3, 5, 7, and 10 cm treatment lengths, respectively. The dose distributions were more homogenous by increasing the position step sizes. The dose difference of the reference point was less than 10%. In brachytherapy, this difference can be negligible. For EBBT, the treatment time is the key factor while considering the patient status. To reduce the total treatment time, EBBT can be performed with 2.5 mm position step size.

• Journal of radiological science and technology
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• v.33 no.3
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• pp.283-288
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• 2010

In order to evaluate radiation dose on the uterus and surrounding organs during brachytherapy for cervical cancer, of which the frequency of occurrence is high in Korean women, as well as radiation dose on medical staffs in proximity of patients receiving the therapy, a mathematical phantom based on reference Korean was established and the radiation dose was calculated accordingly. For simulation, $^{192}Ir$, which is useful in brachytherapy, was selected as radionuclide. Also, it was presumed that the intensity of initial radiation was 1 Ci. The result indicated the radiation of 4.92E-14 Gy/Ci in the uterus, the source organ. In addition, radiation on people around patient receiving the therapy was found to be 1.24E-07 Sv at a distance of 30 cm.

• Journal of the Korean Society of Radiology
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• v.12 no.2
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• pp.167-172
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• 2018

This study evaluated absorbed dose of brachytherapy according to the nanoparticle in prostate cancer which many occurred in Korean man and provided basic data. Absorbed dose evaluation was using MCNPX program which was applied Monte Carlo simulation. Source was applied $^{192}Ir$ which was many using in Korean HDR machine and gold, ferric oxide, gadolinium and iodine nanoparticle were applied. Prostate absorbed dose result was increased when using nanoparticle, in particular gold nanoparticle was the highest result as $3.13E-03J/kg{\cdot}e$. Absorbed dose of surrounding organs and distance was similar between using nanoparticle and non-using nanoparticle. Therefore, brachytherapy was used nanoparticle was increased therapeutic ratio and efficiency of radiation therapy.

• Journal of Sensor Science and Technology
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• v.17 no.6
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• pp.462-469
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• 2008

In this study, we have fabricated a fiber-optic radiation sensor using an organic scintillator and plastic optical fiber for brachytherapy dosimetry. Also, we have measured relative depth dose rates of Ir-192 source using a fiber-optic sensor and compared them with the results obtained using a conventional EBT film. Cerenkov lights which can be a noise in measuring scintillating light with a fiber-optic sensor are measured and eliminated by using of a background optical fiber. It is expected that a fiber-optic radiation sensor can be used in brachytherapy dosimetry due to its advantages such as a low cost, simple usage and a small volume.

• The Journal of Korean Society for Radiation Therapy
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• v.6 no.1
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• pp.56-60
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• 1994

In the past, brachytherapy was carried out mostly with radium or radon sources. Currently. use of artificially produced radionuclially produced radionuclides such as $^{137}Cs,\;^{192}Ir,\;^{198}Au,\;and\;^{125}I$ is rapidly increasing. Although electrons are often used as an alternative to interstitial implants, brachytherapy continues to remain an important mode of therapy, either alone or combined with external beam. The National Council on Radiation Protection and Measurements(NCRP) recommends that the strength of any ${\gamma}$ emitter should be specified directly in terms of exposure rate in air at a specified distance such as 1m. The air kerma strength is defined as the product of air kerma rate in 'free space' and the square of the disrance of the calibration point from the source center along the perpendicular bisector, i. e., $S_k=K_L{\times}L^2$. Where $S_K$ is the the air kerma strength and K is the air kerma rate at a specified distance L. (usually 1m). Recommended units for all kerma strength are ${\mu}Gym^{2}h^{-1}$.

• Progress in Medical Physics
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• v.13 no.2
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• pp.79-84
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• 2002

In this study, a cylindrical ultrasound applicator is developed for the treatment of vagina and rectum in combination with high dose rate brachytherapy. A cylindrical transducer (PZT-8, 1=1.5 cm, thickness=1.5mm OD=2.5 cm) was used as an energy source for induction of hyperthermia. Three single-element applicators were constructed to examine the performance of the PZT material. Vector impedance was measured to determine driving frequency. The efficiencies of the elements were determined using a radiation force technique to evaluate the feasibility of using the applicator as a hyperthermia source. A multi-element ultrasound applicator was designed using the PZT-8 material for the treatment of vagina. Results from the vector impedance measurements showed maximum magnitude at 1.78, 1.77, and 1.77 MHz for applicator 1,2, and 3, respectively. The radiation force measurements showed that the acoustic power of 40 watts was obtained in all three elements. The average efficiencies of the elements were 61.4, 65.2, and 54.0% for element 1, 2, and 3, respectively. The designed ultrasound hyperthermia applicator could be used in combination with high dose rate brachytherapy for the treatment of vagina and rectum. The use of this applicator with intracavitary brachytherapy could offer improved tumor control by increasing radiosensitiyity of the tumor.

• Radiation Oncology Journal
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• v.17 no.1
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• pp.43-51
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• 1999

Purpose : To discuss the technical aspect of interstitial brachytherapy including method of implant, insertion time of radioactive source, total radiation dose, and complication, we reviewed patients who had diagnoses of soft tissue sarcoma and were treated by conservative surgery, interstitial implant and external beam radiation therapy Materials and Methods : Between May 1995 and Dec. 1997, ten patients with primary or recurrent soft tissue sarcoma underwent surgical resection (wide margin excision) and received radiotherapy including interstitial brachytherapy. Catheters were placed with regular intervals of 1 ~l.5 cm immediately after tumor removal and covering the critical structures, such as neurovascular bundle or bone, with gelform, muscle, or tissue expander in the cases where the tumors were close to those structures. Brachytherapy consisted of high dose rate, iridium-192 implant which delivered 12~15 Gy to 1 cm distance from the center of source axis with 2~2.5 Gy/fraction, twice a day, starting on 6th day after the surgery, Within one month after the surgery, total dose of 50~55 Gy was delivered to the tumor bed with wide margin by the external beam radiotherapy. Results : All patients completed planned interstitial brachytherapy without acute side effects directly related with catheter implantation such as infection or bleeding. With median follow up duration of 25 months (range 12~41 months), no local recurrences were observed. And there was no severe form of chronic complication (RTOGIEORTC grade 3 or 4). Conclusion : The high dose rate interstitial brachytherapy is easy and safe way to minimize the radiation dose delivered to the adjacent normal tissue and to decrease radiation induced chronic morbidity such as fibrosis by reducing the total dose of external radiotherapy in the management of soft tissue sarcoma with conservative surgery.

• Journal of the Korean Society of Radiology
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• v.10 no.1
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• pp.39-44
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• 2016

This study is fulfilled to evaluate the exposure dose nearby a patient during the brachytherapy of the prostate cancer treatment and to minimize the radiation exposure by evaluating the exposure dose of the person near the relevant implanted patient, technicians and gardians. The experiment method is used on the study is MCNPX that is stood on the basis monte-carlo method and implant the source to MIRD-type phantom in $^{192}Ir$, $^{125}I$, and $^{103}Pd$ in virtual space. For dose evaluations according to distance, the radiation dose on the patient near the corresponding implanted patient is evaluated by each distance of 30, 50, 100, 200 cm to anterior from the implanted patient. As a result, $^{192}Ir$ showed a higher dose than $^{125}I$ and $^{103}Pd$ in every distance.

• Progress in Medical Physics
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• v.26 no.4
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• pp.280-285
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• 2015

In radiation therapy fields, a brachytherapy is a treatment that kills lesion of cells by inserting a radioisotope that keeps emitting radiation into the body. We currently verify the consistency of radiation treatment plan and dose distribution through film/screen system (F/S system), provide therapy after checking dose. When we check dose distribution, F/S systems have radiation signal distortion because there is low resolution by penumbra depending on the condition of film developed. In this study, We fabricated a $HgI_2$ Semiconductor radiation sensor for base study in order that we verify the real dose distribution weather it's same as plans or not in brachytherapy. Also, we attempt to evaluate the feasibility of QA system by utilizing and evaluating the sensor to brachytherapy source. As shown in the result of detected signal with various source-to-detector distance (SDD), we quantitatively verified the real range of treatment which is also equivalent to treatment plans because only the low signal estimated as scatters was measured beyond the range of treatment. And the result of experiment that we access reproducibility on the same condition of ${\gamma}$-ray, we have made sure that the CV (coefficient of variation) is within 1.5 percent so we consider that the $HgI_2$ sensor is available at QA of brachytherapy based on the result.

• Journal of the Korean Society of Radiology
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• v.17 no.3
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• pp.433-440
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• 2023

High dose rate brachytherapy is a cancer treatment that intensively irradiates radiation to tumors by inserting isotopes with high dose rates into the body. For such a treatment, it is necessary to deliver an accurate dose to the tumor tissue through an accurate treatment plan while delivering only a minimum dose to the normal tissue. Therefore, it is very important to check the location accuracy of the source through accurate Quality Assurance (QA) in clinical practice. However, since the source position is determined using a ruler, automatic radiographer, video monitor, etc. in clinical practice, it yields inaccurate results. In this study, a semiconductor dosimeter using CsPbI₂Br and CsPbIBr₂ was fabricated. And, in order to analyze whether it is more suitable for the relative QA dosimeter for brachytherapy device among the two materials, the radiation detection ability of each was compared and evaluated. In order to evaluate the radiation detection ability in brachytherapy, the reproducibility and linearity of the two materials were evaluated in ¹⁹²IR. In the reproducibility evaluation, CsPbI₂Br presented a Relative Standard Deviatio(RSD) of 0.98% and CsPbIBr₂ presented an RSD of 3.45%. In the linearity evaluation, the coefficient of determination (R²) of CsPbI₂Br was presented as 0.9998, and the R² of CsPbIBr₂ was presented as 0.9994. As a result of the evaluation, it was found that CsPbI₂Br was more stable in radiation detection while satisfying the evaluation criteria in the dosimeter manufactured in this experiment. Therefore, CsPbI₂Br material is suitable for application as a relative dosimeter for radiation detection in brachytherapy devices.