• Journal of Radiation Protection and Research
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• v.48 no.1
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• pp.9-14
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• 2023

Background: The detectors of both computed radiography (CR) and direct digital radiography (DR) have a wide dynamic range that could tolerate high values of exposure factors without an adverse effect on image quality. Therefore, this study aims to assess patient radiation dose and proposes institutional diagnostic reference levels (DRLs) for two teaching hospitals in Ghana. Materials and Methods: CR and DR systems were utilized in this study from two teaching hospitals. The CR system was manufactured by Philips Medical Systems DMC GmbH, while the DR system was manufactured by General Electric. The entrance skin doses (ESDs) were calculated using the standard equation and the tube output measurements. Free-in-air kerma (µGy) was measured using a calibrated radiation dosimeter. The proposed institutional DRLs were estimated using 75^th percentiles values of the estimated ESDs for nine radiographic projections. Results and Discussion: The calculated DRLs were 0.4, 1.6, 3.4, 0.5, 0.4, 1.1, 1.0, 1.2, and 1.7 mGy for chest posteroanterior (PA), lumbar spine anteroposterior (AP), lumbar spine lateral (LAT), cervical spine AP, cervical spine LAT, skull PA, pelvis AP, and abdomen AP, respectively in CR system. In the DR system, the values were 0.3, 1.6, 3.1, 0.4, 0.3, 0.7, 0.6, 0.9, and 1.3 for chest PA, lumbar spine AP, lumbar spine LAT, cervical spine AP, cervical spine LAT, skull PA, pelvis AP, and abdomen AP, respectively. Conclusion: Institutional DRLs in nine radiographic projections have been proposed for two teaching hospitals in Ghana for the first time. The proposed DRLs will serve as baseline data for establishing local DRLs in the hospitals and will be a valuable tool in optimizing patient doses.

• Anatomy and Cell Biology
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• v.56 no.2
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• pp.161-165
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• 2023

The depressor anguli oris (DAO) muscle is a thin, superficial muscle located below the corner of the mouth. It is the target for botulinum neurotoxin (BoNT) injection therapy, aimed at treating drooping mouth corners. Hyperactivity of the DAO muscle can lead to a sad, tired, or angry appearance in some patients. However, it is difficult to inject BoNT into the DAO muscle because its medial border overlaps with the depressor labii inferioris and its lateral border is adjacent to the risorius, zygomaticus major, and platysma muscles. Moreover, a lack of knowledge of the anatomy of the DAO muscle and the properties of BoNT can lead to side effects, such as asymmetrical smiles. Anatomical-based injection sites were provided for the DAO muscle, and the proper injection technique was reviewed. We proposed optimal injection sites based on the external anatomical landmarks of the face. The aim of these guidelines is to standardize the procedure and maximize the effects of BoNT injections while minimizing adverse events, all by reducing the dose unit and injection points.

• The Korean Journal of Nuclear Medicine Technology
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• v.19 no.2
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• pp.74-80
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• 2015

Purpose Breast lymphoscintigraphy is an important technique to present for body surface precisely, which shows a lymph node metastasis of malignant tumors at an early stage and is performed before and after surgery in patients with breast cancer. In this study, we evaluated several methods of body outline imaging to present exact location of lesions, as well as compared respective exposure doses. Materials and Methods RANDO phantom and SYMBIA T-16 were used for obtaining imaging. A lesion and an injection site were created by inserting a point source of 0.11 MBq on the axillary sentinel lymph node and 37 MBq on the right breast, respectively. The first method for acquiring the image was used by drawing the body surface of phantom for 30 sec using $Na^{99m}TcO_4$ as a point source. The second, the image was acquired with $^{57}Co$ flood source for 30 seconds on the rear side and the left side of the phantom, the image as the third method was obtained using a syringe filled with 37 MBq of $Na^{99m}TcO_4$ in 10 ml of saline, and as the fourth, we used a photon energy and scatter energy of $^{99m}Tc$ emitting from phantom without any addition radiation exposure. Finally, the image was fused the scout image and the basal image of SPECT/CT using MATLAB$^{(R)}$ program. Anterior and lateral images were acquired for 3 min, and radiation exposure was measured by the personal exposure dosimeter. We conducted preference of 10 images from nuclear medicine doctors by the survey. Results TBR values of anterior and right image in the first to fifth method were 334.9 and 117.2 ($1^{st}$), 266.1 and 124.4 ($2^{nd}$), 117.4 and 99.6 ($3^{rd}$), 3.2 and 7.6 ($4^{th}$), and 565.6 and 141.8 ($5^{th}$). And also exposure doses of these method were 2, 2, 2, 0, and $30{\mu}Sv$, respectively. Among five methods, the fifth method showed the highest TBR value as well as exposure dose, where as the fourth method showed the lowest TBR value and exposure dose. As a result, the last method ($5^{th}$) is the best method and the fourth method is the worst method in this study. Conclusion Scout method of SPECT/CT can be useful that provides the best values of TBR and the best score of survey result. Even though personal exposure dose when patients take scout of SPECT/CT was higher than another scan, it was slight level comparison to 1 mSv as the dose limit to non-radiation workers. If the scout is possible to less than 80 kV, exposure dose can be reduced, and also useful lesion localization provided.

• Radiation Oncology Journal
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• v.18 no.1
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• pp.1-10
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• 2000

Purpose : Although using the high energy Photon beam with conventional Parallel-opposed beams radiotherapy for nasopharyngeal carcinoma, radiation-induced xerostomia is a troublesome problem for patients. We conducted this study to explore a new parotid gland sparing technique in 3-D conformal radiotherapy (3-D CRT) in an effort to prevent the radiation-induced xerostomia. Materials and Methods : We peformed three different planning for four clinically node-negative nasopharyngeal cancer patients with different location of tumor(intracranial extension, nasal cavity extension, oropharyngeal extension, parapharyngeal extension), and intercompared the plans. Total prescription dose was 70.2 Gy to the isocenter. For plan-A, 2-D parallel opposing fields, a conventional radiotherapy technique, were employed. For plan-B, 2-D parallel opposing fields were used up until 54 Gy and afterwards 3-D non-coplanar beams were used. For plan-C, the new technique, 54 Gy was delivered by 3-D conformal 3-port beams (AP and both lateral ports with wedge compensator; shielding both superficial lobes of parotid glands at the AP beam using BEV) from the beginning of the treatment and early spinal cord block (at 36 Gy) was peformed. And bilateral posterior necks were treated with electron after 36 Gy. After 54 Gy, non-coplanar beams were used for cone-down plan. We intercompared dose statistics (Dmax, Dmin, Dmean, D95, DO5, V95, VOS, Volume receiving 46 Gy) and dose volume histograms (DVH) of tumor and normal tissues and NTCP values of parotid glands for the above three plans. Results : For all patients, the new technique (plan-C) was comparable or superior to the other plans in target volume isodose distribution and dose statistics and it has more homogenous target volume coverage. The new technique was most superior to the other plans in parotid glands sparing (volume receiving 46 Gy: 100, 98, 69$\%$ for each plan-A, B and C). And it showed the lowest NTCP value of parotid glands in all patients (range of NTCP; 96$\~$100$\%$, 79$\~$99$\%$, 51$\~$72$\%$ for each plan-A, B and C). Conclusion : We conclude that the new technique employing 3-D conformal radiotherapy at the beginning of radiotherapy and cone down using non-coplanar beams with early spinal cord block is highly recommended to spare parotid glands for node-negative nasopharygeal cancer patients.

• The Journal of Korean Society for Radiation Therapy
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• v.16 no.1
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• pp.29-37
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• 2004

Purpose : A rectum and a bladder should be carefully considered in order to decrease side effects when HDR patient of uterine cervix cancer. Generally speaking, the value of dosimeter at a rectum and a bladder only depends on the value of a planning equipment, while some analyses of the value of dosimetry at rectum with TLD has been reported Or the contrary, it is hardly to find a report with in vivo dosimetry(diode detector). On this thesis, we would like to suggest the following. When a patient of uterine cervix cancer is in therapy, it is helpful to put a diode detector inside of a rectum in order to measure the rectal dose Based upon the result of the dosimetry, the result can be used as basic data at decreasing side effects. Materials and Methods : Six patients of uterine cervix cancer(four with tandem and ovoid, one with cylinder, and the other one with tandem and cylinder) who had been irradiated with HDR. Ir-192 totally 28 times from February 2003 to June 2003. We irradiated twice in the same distant spots with anterior film and lateral film whenever we measured with a diode detector. Then we did planning and compared each film. Results : The result of the measurement 4 patients with a diode detector is the following. The average and deviation from 3 patients with tandem and ovoid were $274.1{\pm}13.4cGy$, from 1 patient with tandem and ovoid were $126.1{\pm}7.2cGy$, from 1 patient with cylinder were $99.7{\pm}7.1cGy$, and from 1 patient with tandem and cylinder were $77.7{\pm}11.5cGy$. Conclusion : It is difficult to predict how the side effect of a rectum since the result of measurement with a diode detector depends on the state of a rectum. According to the result of the study, it is effective to use a TLD or an in vivo dosimetry and measure a rectum in order to consider the side effect. It is very necessary to decrease the amount of irradiation by controlling properly the duration of the irradiation and gauze packing, and by using shield equipments especially when side effects can be expected.

• Journal of radiological science and technology
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• v.28 no.4
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• pp.293-299
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• 2005

In the present investigation, we analyzed the data of 1,318 patients (2,636 images) who underwent mammographic examinations and obtained the distribution of the patient age and compressed breast thickness. We measured also average glandular doses (AGD) as function of compressed breast thickness. In order to obtain the values of AGD, we measured half value layer (HVL) and tube output (mR/mAs) for each kVp and target/filter combination. Entrance surface air kerma (ESAK) was calculated from the tube output as measured for each voltage used under clinical conditions and from the tube loading (mAs). AGD per exposure were calculated by multiplying the ESAK values by the conversion factors tabulated by Dance. We obtained in this study the following conclusions. The mean value of compressed breast thickness for cranio-caudal (CC) view was 35.8mm and that for medio-lateral oblique (MLO) view was 43.3 mm. The mean value of AGD for CC view was 1.55 mGy and that for MLO view was 1.70 mGy. The AGD for MLO view was 0.15 mGy (10%) higher than that for CC view because the thickness for MLO view was on average 4.8 mm higher than that for CC view. The values of AGD increased with increasing compressed brest thickness. The increased AGD value was on average 0.34 mGy per 10 mm in the thickness ranges $10{\sim}80\;mm$, therefore differences between the AGD values of each thickness were relative large. Thus, it is considered to need limited doses for mammography with the upper end of exposure range at several different compressed brest thickness.

• Radiation Oncology Journal
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• v.23 no.4
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• pp.236-242
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• 2005

Purpose: To evaluate the role of surgical clips and scars in determining electron boost field for early stage breast cancer undergoing conserving surgery and postoperative radiotherapy and to provide an optimal method in drawing the boost field. Materials and Methods: Twenty patients who had $4{\sim}7$ surgical clips in the excision cavity were selected for this study. The depth informations were obtained to determine electron energy by measuring the distance from the skin to chest wall (SCD) and to the clip implanted in the most posterior area of tumor bed. Three different electron fields were outlined on a simulation film. The radiological tumor bed was determined by connecting all the clips implanted during surgery Clinical field (CF) was drawn by adding 3 cm margin around surgical scar. Surgical field (SF) was drawn by adding 2 cm margin around surgical clips and an Ideal field (IF) was outlined by adding 2 cm margin around both scar and clips. These fields were digitized into our planning system to measure the area of each separate field. The areas of the three different electron boost fields were compared. Finally, surgical clips were contoured on axial CT images and dose volume histogram was plotted to investigate 3-dimensional coverage of the clips. Results : The average depth difference between SCD and the maximal clip location was $0.7{\pm}0.55cm$. Greater difference of 5 mm or more was seen in 12 patients. The average shift between the borders of scar and clips were 1.7 1.2, 1.2, and 0.9 cm in superior, inferior, medial, and lateral directions, respectively. The area of the CF was larger than SF and IF in 6y20 patients. In 15/20 patients, the area difference between SF and if was less than 5%. One to three clips were seen outside the CF in 15/20 patients. In addition, dosimetrically inadequate coverage of clips (less than 80% of prescribed dose) were observed in 17/20 patients when CF was used as the boost field. Conclusion: The electron field determined from clinical scar underestimates the tumor bed in superior-inferior direction significantly and thereby underdosing the tissue at risk. The electron field obtained from surgical clips alone dose not cover the entire scar properly As a consequence, our technique, which combines the surgical clips and clinical scars in determining electron boost field, was proved to be effective in minimizing the geographical miss as well as normal tissue complications.

• The Journal of Korean Society for Radiation Therapy
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• v.26 no.1
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• pp.69-76
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• 2014

Purpose : To evaluate the changes of the motion of abdominal cavity between interfraction and intrafraction by using abdominal compression for reducing abdominal motion. Materials and Methods : 60 MVCT images were obtained before and after tomotherapy from 10 prostate cancer patients over the whole radiotherapy period. Shift values ( X -lateral Y -longitudinal Z -vertical and Roll ) were measured and from it, the correlation of between interfraction set up change and intrafraction target motion was analyzed when applying abdominal compression. Results : The motion changes of interfraction were X-average $0.65{\pm}2.32mm$, Y-average $1.41{\pm}4.83mm$, Z-average $0.73{\pm}0.52mm$ and Roll-average $0.96{\pm}0.21mm$. The motion changes of intrafraction were X-average $0.15{\pm}0.44mm$, Y-average $0.13{\pm}0.44mm$, Z-average $0.24{\pm}0.64mm$ and Roll-average $0.1{\pm}0.9mm$. The average PTV maximum dose difference was minimum for 10% phase and maximum for 70% phase. The average Spain cord maximum dose difference was minimum for 0% phase and maximum for 50% phase. The average difference of $V_{20}$, $V_{10}$, $V_5$ of Lung show bo certain trend. Conclusion : Abdominal compression can minimize the motion of internal organs and patients. So it is considered to be able to get more ideal dose volume without damage of normal structures from generating margin in small in producing PTV.

• The Journal of Korean Society for Radiation Therapy
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• v.16 no.2
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• pp.43-61
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• 2004

Purpose : For qualify improvement in radiotherapy, it is important to set up and evaluate equipment (linac) accurately. In addition, technicians are needed to be fully aware of the equipment's detailed quality and its manual. Therefore, the result of ATP is evaluated and introduced, in order that the technicians are skilled by participating in quality assurance (QA) and understanding the quality of the equipment before clinical use. Method and Material : QA for LINAC 21EX (Varian, US) was done with suppliers its procedure was divided into radiation survey, mechanical test, radiation isocenter test, bean performance, dosimetry, and enhanced dynamic wedge and using X-omat film (Kodak), multidata, densitometer, and electrometer. QA of MLC (Millennium, 120 leaf) attached to LINAC and EPID (Portal vision) were done separately. Result : The leakage dose by survey meter was below the tolerance. In mechanical test, collimater, gantry, and couch rotation were less than 1mm, and the angles were ${\pm}0.1^{\circ}$ for digital and ${\pm}0.5^{\circ}$ for mechanical. The alignment test of the light field and crosshair were evaluated less than 1mm. The (a)symmetrical jaw field was less than ${\pm}0.5mm$. The radiation isocenter test using X-mat film was less than 1mm. The consistency of light field and radiation field was less than ${\pm}0.1mm$. PDD for photon energy was less than ${\pm}1\%$ and for electron energy of $90\%,\;80\%,\;50\%,\;and\;30\%$ were evaluated within the tolerance. Flatness for photon and electron energy was evaluated $2.3\%$ (tolerance $3\%$) and $3\%$ (tolerance $4.5\%$), respectively, and symmetry was $0.45\%$ (tolerance $2\%$) and $0.3\%$ (tolerance $2\%$), respectively. Dosimetry test for short term, MU setting, rep rate, and dose rate accuracy of photon and electron energy was within the tolerance depending on energy, MU, and gantry angle. Conclusion : Accuracy and safety for clinical use of Clinac 21EX was verified through customer acceptance procedure and the quality of the equipment was found out. These can reduce the difficulties in using the equipment. Furthermore, it is useful for clinically treatment of patients by technicians' active participations.

• Journal of radiological science and technology
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• v.35 no.3
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• pp.265-273
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• 2012

Aquisition of accurate beam data is very important to calculate a reliable dose distribution of the treatment planning system for small radiation fields in intensity-modulated radiation therapy(IMRT) and stereotactic radiosurgery(SRS). For the measurement of small fields, the choice of a suitable detector is important due to the shape gradient in profile penumbra, the lack of lateral electronic equilibrium, and the effect of effective detector volume. Therefore, this study was to analyze the dosimetric characteristics of various detectors in measurement of beam data for small fields of linear accelerator. 0.01cc and 0.13cc ion chambers (CC01 and CC13) and a stereotactic diode detector(SFD) were used for measurement of small fields. The beam data, including the percent depth dose, output factor, and beam profile were acquired under 6 MV and 15 MV photon beams. Measurements were performed with the field size ranging from $2{\times}2cm^2$ to $5{\times}5cm^2$. For $2{\times}2cm^2$ field size, the differences of the ratios of $PDD_{20}$ and $PDD_{10}$ measured by CC01 and SFD detectors were 1.02% and 0.12% for 6 MV and 15 MV photon beams, respectively. For field sizes larger than $3{\times}3cm^2$, the differences of values of $PDD_{20}/PDD_{10}$ obtained from each detector were 1.15% and 0.71% for 6 MV and 15 MV photon beams, respectively. The output factors obtained from CC01 and SFD for $2{\times}2cm^2$ field size were within 0.5% and 1.5% for 6 MV and 15 MV, respectively. The differences in output factor of three detectors for $3{\times}3cm^2$ to $5{\times}5cm^2$ field sizes were within 0.5%. Profile penumbras measured by the SFD, CC01, and CC13 detectors at three depths were average 2.7 mm and 3.5 mm, 3.4 mm and 4.3 mm, and 5.2 mm and 6.1 mm for 6 MV and 15 MV photon beams, respectively. In conclusion, it could be possible to use of the CC01 and SFD detectors for the measurement of percent depth dose and output factor for $2{\times}2cm^2$ field size, and to use of three detectors for $3{\times}3cm^2$ to $5{\times}5cm^2$ field sizes. CC01 and SFD detectors, consider ably smaller than the radiation field, should be used in order to accurately measure the profile penumbra for small field sizes.