Korean Society of Medical Physics

Original Article

Development of a Flexible Eye Shield Phantom for Artifact-Free Computed Tomography Images

Progress in Medical Physics 2024; 35(3): 59-64

Original Article

Analysis of the Multi-Leaf Collimator Quality Assurance for the Halcyon^TM Linear Accelerator

Progress in Medical Physics 2024; 35(2): 45-51

Original Article

Dosimetric Evaluations of HyperArc and RapidArc in Stereotactic Radiosurgery for a Single Brain Metastasis

Progress in Medical Physics 2024; 35(2): 36-44

Review Article

Motion Management and Image-Guided Technique in Photon Radiation Therapy: A Review of an Advanced Technology

Progress in Medical Physics 2024; 35(2): 21-35

Original Article 2024-09-30

Development of a Flexible Eye Shield Phantom for Artifact-Free Computed Tomography Images

Seonghee Kang^1,2,3 , Chang Heon Choi^1,2,3 , Jung-in Kim^1,2,3 , Geum Bong Yu^2,4 , Jin Dong Cho⁵

Progress in Medical Physics 2024; 35(3): 59-64
https://doi.org/10.14316/pmp.2024.35.3.59

Abstract

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Purpose: This study aimed to develop a flexible eye shield phantom to acquire artifact-free computed tomography (CT) images for electron beam radiotherapy.
Methods: A flexible eye shield phantom for a newly designed eye shield was fabricated. Because of metal artifacts caused by an eye shield composed of high-density materials such as tungsten or lead, CT image acquisition is not appropriate for treatment planning because of inaccurate dose calculation and organ-at-risk delineation. To acquire artifact-free CT images, a mold of the same size as the outer dimension of the metallic eye shield was manufactured using 3D printing. The flexible eye shield phantom was imaged using a Philips Brilliance CT Big Bore under the same condition as the measurement. The phantom image with an average of 200 Hounsfield unit (HU) was imported into the treatment planning systems (TPS) and assigned a value of 26,750 HU to consider the material density of tungsten. The dosimetric comparison using a 6-MeV electron beam was performed. Measurement was performed using a metal oxide semiconductor field effect transistor detector for point doses at 3 and 10 mm.
Results: The artifact-free CT images using a flexible eye shield phantom without air bubbles were transferred into the TPS. The dose at 10 mm calculated using the TPS agreed with the ionchamber measurements within 2 cGy. Conversely, a larger dose discrepancy between the measured and calculated doses was found at 3 mm depth.
Conclusions: The flexible eye shield phantom was successfully fabricated to apply electron treatment planning by acquiring artifact-free CT images. The dose calculated using the artifact-free image was comparable to the measured dose at lens depth when applying an eye shield.
Original Article 2024-09-30

Impact of Smaller Gantry Arc Increments on Volumetric Modulated Arc Radiation Therapy in the Monaco Treatment Planning System

Seonghee Kang^1,2,3 , Hyejo Ryu⁴ , Do Hoon Oh⁴ , Lee Yoo⁴ , Minsoo Chun^2,4,5

Progress in Medical Physics 2024; 35(3): 65-72
https://doi.org/10.14316/pmp.2024.35.3.65

Abstract

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Purpose: This study aims to evaluate the impact of smaller gantry arc increment (GAI) values on the plan quality and deliverability of volumetric modulated arc therapy (VMAT) for head and neck (HN) and prostate cancer cases using the Monaco treatment planning system. The study investigates whether a smaller GAI can enhance organ at risk (OAR) sparing without compromising target coverage or significantly increasing plan complexity.
Methods: VMAT plans were created for 20 patients (10 HN and 10 prostate cancer) using GAI values of 15° and 30°. Dose-volumetric parameters, such as conformity number, homogeneity and gradient indices, were assessed alongside plan complexity metrics like the modulation complexity score for VMAT (MCSv) and monitor unit (MU). Statistical significance was determined using the Wilcoxon signed-rank test.
Results: For HN cases, a 15° increment significantly reduced the D_0.03cc for the spinal cord and the D_mean for both parotid glands compared to a 30° increment, improving OAR sparing. However, no significant differences were observed in the OAR doses for prostate cases. The 15° increment resulted in higher plan complexity, reflected by a lower MCS_v, but the MU difference was not significant.
Conclusions: Smaller GAI values, such as 15°, can significantly reduce OAR doses in HN VMAT plans, offering potential clinical benefits despite increased plan complexity. However, no substantial advantages were observed in prostate cases. These findings suggest that smaller GAI values may be particularly beneficial for cases requiring high modulation.

Technical Note 2022-12-31

50–300 kVp X-ray Transmission Ratios for Lead, Steel and Concrete

Tae Hwan Kim^2,5 , Kum Bae Kim³ , Geun Beom Kim¹ , Dong Wook Kim³ , Sang Rok Kim² , Sang Hyoun Choi¹

Progress in Medical Physics 2022; 33(4): 164-171
https://doi.org/10.14316/pmp.2022.33.4.164

Abstract

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The number of facilities using radiation generators increases and related regulations are strengthened, the establishment of a shielding management and evaluation technology has become important. The characteristics of the radiation generator used in previous report differ from those of currently available high-frequency radiation generators. This study aimed to manufacture lead, iron, and concrete shielding materials for the re-verification of half-value layers, tenth-value layers, and attenuation curve. For a comparison of attenuation ratio, iron, lead, and concrete shields were manufactured in this study. The initial dose was measured without shielding materials, and doses measured under different types and thicknesses of shielding material were compared with the initial dose to calculate the transmission rate on 50–300 kVp X-ray. All the three shielding materials showed a tendency to require greater shielding thickness for higher energy. The attenuation graph showed an exponential shape as the thickness decreased and a straight line as the thickness increased. The difference between the measurement results and the previous study, except in extrapolated parts, may be due to the differences in the radiation generation characteristics between the generators used in the two studies. The attenuated graph measured in this study better reflects the characteristics of current radiation generators, which would be more effective for shield designing.
Review Article 2022-12-31

Image Guided Radiation Therapy

Ui-Jung Hwang¹ , Byong Jun Min² , Meyoung Kim³ , Ki-Hwan Kim¹

Progress in Medical Physics 2022; 33(4): 37-52
https://doi.org/10.14316/pmp.2022.33.4.37

Abstract

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Over the past decades, radiation therapy combined with imaging modalities that ensure optimal image guidance has revolutionized cancer treatment. The two major purposes of using imaging modalities in radiotherapy are to clearly delineate the target prior to treatment and set up the patient during radiation delivery. Image guidance secures target position prior to and during the treatment. High quality images provide an accurate definition of the treatment target and the possibility to reduce the treatment margin of the target volume, further lowering radiation toxicity and improving the quality of life of cancer patients. In this review, the various types of image guidance modalities used in radiation therapy are distinguished into ionized (kilovoltage and megavoltage image) and nonionized imaging (magnetic resonance image, ultrasound, surface imaging, and radiofrequency). The functional aspects, advantages, and limitation of imaging using these modalities are described as a subsection of each category. This review only focuses on the technological viewpoint of these modalities and any clinical aspects are omitted. Image guidance is essential, and its importance is rapidly increasing in modern radiotherapy. The most important aspect of using image guidance in clinical settings is to monitor the performance of image quality, which must be checked during the periodic quality assurance process.
Review Article 2022-12-31

Review of Shielding Evaluation Methodology for Facilities Using kV Energy Radiation Generating Devices Based on the NCRP-49 Report

Na Hye Kwon^1,2 , Hye Sung Park³ , Taehwan Kim^4,5 , Sang Rok Kim⁵ , Kum Bae Kim^6,7 , Jin Sung Kim^1,2,8 , Sang Hyoun Choi^6,7 , Dong Wook Kim^1,2

Progress in Medical Physics 2022; 33(4): 53-62
https://doi.org/10.14316/pmp.2022.33.4.53

Abstract

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In this study, we have investigated the shielding evaluation methodology for facilities using kV energy generators. We have collected and analysis of safety evaluation criteria and methodology for overseas facilities using radiation generators. And we investigated the current status of shielding evaluation of domestic industrial radiation generators. According to the statistical data from the Radiation Safety Information System, as of 2022, a total of 7,679 organizations are using radiation generating devices. Among them, 6,299 facilities use these devices for industrial purposes, which accounts for a considerable portion of radiation. The organizations that use these devices evaluate whether the exposure dose for workers and frequent visitors is suitable as per the limit regulated by the Nuclear Safety Act. Moreover, during this process, the safety shields are evaluated at the facilities that use the radiation generating devices. However, the facilities that use radiating devices having energy less than or equal to 6 MV for industrial purposes are still mostly evaluated and analyzed according to the National Council on Radiation Protection and Measurements 49 (NCRP 49) report published in 1976. We have investigated the technical standards of safety management, including the maximum permissible dose and parameters assessment criteria for facilities using radiation generating devices, based on the NCRP 49 and the American National Standards Institute/Health Physics Society N.43.3 reports, which are the representative reports related to radiation shielding management cases overseas.
Original Article 2023-09-30

Influence of Two-Dimensional and Three-Dimensional Acquisitions of Radiomic Features for Prediction Accuracy

Ryohei Fukui , Ryutarou Matsuura , Katsuhiro Kida , Sachiko Goto

Progress in Medical Physics 2023; 34(3): 23-32
https://doi.org/10.14316/pmp.2023.34.3.23

Abstract

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Purpose: In radiomics analysis, to evaluate features, and predict genetic characteristics and survival time, the pixel values of lesions depicted in computed tomography (CT) and magnetic resonance imaging (MRI) images are used. CT and MRI offer three-dimensional images, thus producing three-dimensional features (Features_3d) as output. However, in reports, the superiority between Features_3d and two-dimensional features (Features_2d) is distinct. In this study, we aimed to investigate whether a difference exists in the prediction accuracy of radiomics analysis of lung cancer using Features_2d and Features_3d.
Methods: A total of 38 cases of large cell carcinoma (LCC) and 40 cases of squamous cell carcinoma (SCC) were selected for this study. Two- and three-dimensional lesion segmentations were performed. A total of 774 features were obtained. Using least absolute shrinkage and selection operator regression, seven Features_2d and six Features_3d were obtained.
Results: Linear discriminant analysis revealed that the sensitivities of Features_2d and Features_3d to LCC were 86.8% and 89.5%, respectively. The coefficients of determination through multiple regression analysis and the areas under the receiver operating characteristic curve (AUC) were 0.68 and 0.70 and 0.93 and 0.94, respectively. The P-value of the estimated AUC was 0.87.
Conclusions: No difference was found in the prediction accuracy for LCC and SCC between Features_2d and Features_3d.
Original Article 2022-12-31

Dead Layer Thickness and Geometry Optimization of HPGe Detector Based on Monte Carlo Simulation

Suah Yu^1,2 , Na Hye Kwon³ , Young Jae Jang¹ , Byungchae Lee⁴ , Jihyun Yu⁴ , Dong-Wook Kim³ , Gyu-Seok Cho¹ , Kum-Bae Kim¹ , Geun Beom Kim¹ , Cheol Ha Baek² , Sang Hyoun Choi¹

Progress in Medical Physics 2022; 33(4): 129-135
https://doi.org/10.14316/pmp.2022.33.4.129

Abstract

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Purpose: A full-energy-peak (FEP) efficiency correction is required through a Monte Carlo simulation for accurate radioactivity measurement, considering the geometrical characteristics of the detector and the sample. However, a relative deviation (RD) occurs between the measurement and calculation efficiencies when modeling using the data provided by the manufacturers due to the randomly generated dead layer. This study aims to optimize the structure of the detector by determining the dead layer thickness based on Monte Carlo simulation.
Methods: The high-purity germanium (HPGe) detector used in this study was a coaxial p-type GC2518 model, and a certified reference material (CRM) was used to measure the FEP efficiency. Using the MC N-Particle Transport Code (MCNP) code, the FEP efficiency was calculated by increasing the thickness of the outer and inner dead layer in proportion to the thickness of the electrode.
Results: As the thickness of the outer and inner dead layer increased by 0.1 mm and 0.1 µm, the efficiency difference decreased by 2.43% on average up to 1.0 mm and 1.0 µm and increased by 1.86% thereafter. Therefore, the structure of the detector was optimized by determining 1.0 mm and 1.0 µm as thickness of the dead layer.
Conclusions: The effect of the dead layer on the FEP efficiency was evaluated, and an excellent agreement between the measured and calculated efficiencies was confirmed with RDs of less than 4%. It suggests that the optimized HPGe detector can be used to measure the accurate radioactivity using in dismantling and disposing medical linear accelerators.
Original Article 2023-09-30

Initial Dosimetry of a Prototype Ultra-High Dose Rate Electron-Beam Irradiator for FLASH RT Preclinical Studies

Hyun Kim , Heuijin Lim , Sang Koo Kang , Sang Jin Lee , Tae Woo Kang , Seung Wook Kim , Wung-Hoa Park , Manwoo Lee , Kyoung Won Jang , Dong Hyeok Jeong

Progress in Medical Physics 2023; 34(3): 33-39
https://doi.org/10.14316/pmp.2023.34.3.33

Abstract

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Purpose: FLASH radiotherapy (RT) using ultra-high dose rate (>40 Gy/s) radiation is being studied worldwide. However, experimental studies such as preclinical studies using small animals are difficult to perform due to the limited availability of irradiation devices and methods for generating a FLASH beam. In this paper, we report the initial dosimetry results of a prototype electron linear accelerator (LINAC)-based irradiation system to perform ultra-high dose rate (UHDR) preclinical experiments.
Methods: The present study used the prototype electron LINAC developed by the Research Center of Dongnam Institute of Radiological and Medical Sciences (DIRAMS) in Korea. We investigated the beam current dependence of the depth dose to determine the optimal beam current for preclinical experiments. The dose rate in the UHDR region was measured by film dosimetry.
Results: Depth dose measurements showed that the optimal beam current for preclinical experiments was approximately 33 mA, corresponding to a mean energy of 4.4 MeV. Additionally, the average dose rates of 80.4 Gy/s and 162.0 Gy/s at a source-to-phantom surface distance of 30 cm were obtained at pulse repetition frequencies of 100 Hz and 200 Hz, respectively. The dose per pulse and instantaneous dose rate were estimated to be approximately 0.80 Gy and 3.8×10⁵ Gy/s, respectively.
Conclusions: Film dosimetry verified the appropriate dose rates to perform FLASH RT preclinical studies using the developed electron-beam irradiator. However, further research on the development of innovative beam monitoring systems and stabilization of the accelerator beam is required.
Technical Note 2023-03-31

Clinical Impact of Patient’s Head Position in Supraclavicular Irradiation of the Whole Breast Radiotherapy

Surega Anbumani , Lohith G. Reddy , Priyadarshini V , Sasikala P , Ramesh S. Bilimagga

Progress in Medical Physics 2023; 34(1): 10-13
https://doi.org/10.14316/pmp.2023.34.1.10

Abstract

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Patients with breast cancer can be positioned with their head turned to the contra lateral side or with their head straight during the radiation therapy treatment set-up. In our hospital, patients with locally advanced breast cancer who were receiving radiation therapy have experienced swallowing difficulty after 2 weeks of irradiation. In this pilot study, the impact of head position on reducing dysphagia occurrence was dosimetrically evaluated. Patients were divided into two groups viz., HT (head turned to the contra lateral side of the breast) and HS (head straight) with 10 members in each. Treatment planning was performed, and the dosimetric parameters such as Dmin, Dmax, Dmean, V₅, V₁₀, V₂₀, V₃₀, V₄₀, and V₅₀ of both groups were extracted from the dose volume histogram (DVH) of esophagus. The target coverage in the supraclavicular fossa (SCF) region was analyzed using D₉₅ and D₉₈; moreover, the dose heterogeneity was assessed with D₂ from the DVHs. The average values of the dose volume parameters were 27.6%, 58.6%, 35.4%, 19%, 13.8%, 14.1%, 11.8%, 8.4%, and 8.1% higher in the HT group compared with those in the HS group. Furthermore, for the SCF, the mean values of D₉₈, D₉₅, and D₂ were 42.4, 47.5, and 54 Gy, respectively, in the HS group and 38.9, 45.35, and 55.5 Gy, respectively, in the HT group. This pilot study attempts to give a solution for the poor quality of life of patients after breast radiotherapy due to dysphagia. The findings confirm that the head position could play a significant role in alleviating esophageal toxicity without compromising tumor control.
Technical Note 2023-06-30

Comparison between Old and New Versions of Electron Monte Carlo (eMC) Dose Calculation

Seongmoon Jung^1,2,3,4 , Jaeman Son^1,2,3 , Hyeongmin Jin^1,2,3 , Seonghee Kang^1,2,3 , Jong Min Park^1,2,3,5 , Jung-in Kim^1,3,5 , Chang Heon Choi^1,3,5

Progress in Medical Physics 2023; 34(2): 15-22
https://doi.org/10.14316/pmp.2023.34.2.15

Abstract

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This study compared the dose calculated using the electron Monte Carlo (eMC) dose calculation algorithm employing the old version (eMC V13.7) of the Varian Eclipse treatment-planning system (TPS) and its newer version (eMC V16.1). The eMC V16.1 was configured using the same beam data as the eMC V13.7. Beam data measured using the VitalBeam linear accelerator were implemented. A box-shaped water phantom (30×30×30 cm³) was generated in the TPS. Consequently, the TPS with eMC V13.7 and eMC V16.1 calculated the dose to the water phantom delivered by electron beams of various energies with a field size of 10×10 cm². The calculations were repeated while changing the dose-smoothing levels and normalization method. Subsequently, the percentage depth dose and lateral profile of the dose distributions acquired by eMC V13.7 and eMC V16.1 were analyzed. In addition, the dose-volume histogram (DVH) differences between the two versions for the heterogeneous phantom with bone and lung inserted were compared. The doses calculated using eMC V16.1 were similar to those calculated using eMC V13.7 for the homogenous phantoms. However, a DVH difference was observed in the heterogeneous phantom, particularly in the bone material. The dose distribution calculated using eMC V16.1 was comparable to that of eMC V13.7 in the case of homogenous phantoms. The version changes resulted in a different DVH for the heterogeneous phantoms. However, further investigations to assess the DVH differences in patients and experimental validations for eMC V16.1, particularly for heterogeneous geometry, are required.
Original Article 2023-03-31

Feasibility of a Linear Diode Array Detector for Commissioning of a Radiotherapy Planning System

Seung Mo Hong , Uiseob Lee , Sung-woo Kim , Youngmoon Goh , Min-Jae Park , Chiyoung Jeong , Jungwon Kwak , Byungchul Cho

Progress in Medical Physics 2023; 34(1): 1-9
https://doi.org/10.14316/pmp.2023.34.1.1

Abstract

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Purpose: Although ionization chambers are widely used to measure beam commissioning data, point-by-point measurements of all the profiles with various field size and depths are timeconsuming tasks. As an alternative, we investigated the feasibility of a linear diode array for commissioning a treatment planning system.
Methods: The beam data of a Varian TrueBeam^® radiotherapy system at 6 and 10 MV with/without a flattening filter were measured for commissioning of an Eclipse Analytical Anisotropic Algorithm (AAA) ver.15.6. All of the necessary beam data were measured using an IBA CC13 ionization chamber and validated against Varian “Golden Beam” data. After validation, the measured CC13 profiles were used for commissioning the Eclipse AAA (AAA_CC13). In addition, an IBA LDA-99SC linear diode array detector was used to measure all of the beam profiles and for commissioning a separate model (AAA_LDA99). Finally, the AAA_CC13 and AAA_LDA99 dose calculations for each of the 10 clinical plans were compared.
Results: The agreement of the CC13 profiles with the Varian Golden Beam data was confirmed within 1% except in the penumbral region, where ≤2% of a discrepancy related to machinespecific jaw calibration was observed. Since the volume was larger for the CC13 chamber than for the LDA-99SC chamber, the penumbra widths were larger in the CC13 profiles, resulting in ≤5% differences. However, after beam modeling, the penumbral widths agreed within 0.1 mm. Finally the AAA_LDA99 and AAA_CC13 dose distributions agreed within 1% for all voxels inside the body for the 10 clinical plans.
Conclusions: In conclusion, the LDA-99SC diode array detector was found to be accurate and efficient for measuring photon beam profiles to commission treatment planning systems.
Original Article 2022-12-31

Measurement of Proton Beam Dose-Averaged Linear Energy Transfer Using a Radiochromic Film

Seohyeon An^1,2 , Sang-il Pak¹ , Seonghoon Jeong¹ , Soonki Min³ , Tae Jeong Kim² , Dongho Shin¹ , Youngkyung Lim¹ , Jong Hwi Jeong¹ , Haksoo Kim¹ , Se Byeong Lee¹

Progress in Medical Physics 2022; 33(4): 80-87
https://doi.org/10.14316/pmp.2022.33.4.80

Abstract

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Purpose: Proton therapy has different relative biological effectiveness (RBE) compared with X-ray treatment, which is the standard in radiation therapy, and the fixed RBE value of 1.1 is widely used. However, RBE depends on a charged particle’s linear energy transfer (LET); therefore, measuring LET is important. We have developed a LET measurement method using the inefficiency characteristic of an EBT3 film on a proton beam’s Bragg peak (BP) region.
Methods: A Gafchromic EBT3 film was used to measure the proton beam LET. It measured the dose at a 10-cm pristine BP proton beam in water to determine the quenching factor of the EBT3 film as a reference beam condition. Monte Carlo (MC) calculations of dose-averaged LET (LET_d) were used to determine the quenching factor and validation. The dose-averaged LETs at the 12-, 16-, and 20-cm pristine BP proton beam in water were calculated with the quenching factor.
Results: Using the passive scattering proton beam nozzle of the National Cancer Center in Korea, the LET_d was measured for each beam range. The quenching factor was determined to be 26.15 with 0.3% uncertainty under the reference beam condition. The dose-averaged LETs were measured for each test beam condition.
Conclusions: We developed a method for measuring the proton beam LET using an EBT3 film. This study showed that the magnitude of the quenching effect can be estimated using only one beam range, and the quenching factor determined under the reference condition can be applied to any therapeutic proton beam range.
Technical Note 2022-12-31

TET2DICOM-GUI: Graphical User Interface Based TET2DICOM Program to Convert Tetrahedral-Mesh-Phantom to DICOM-RT Dataset

Se Hyung Lee^1,2 , Bo-Wi Cheon³ , Chul Hee Min³ , Haegin Han¹ , Chan Hyeong Kim¹ , Min Cheol Han⁴ , Seonghoon Kim⁵

Progress in Medical Physics 2022; 33(4): 172-179
https://doi.org/10.14316/pmp.2022.33.4.172

Abstract

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Recently, tetrahedral phantoms have been newly adopted as international standard mesh-type reference computational phantoms (MRCPs) by the International Commission on Radiological Protection, and a program has been developed to convert them to computational tomography images and DICOM-RT structure files for application of radiotherapy. Through this program, the use of the tetrahedral standard phantom has become available in clinical practice, but utilization has been difficult due to various library dependencies requiring a lot of time and effort for installation. To overcome this limitation, in this study a newly developed TET2DICOM-GUI, a TET2DICOM program based on a graphical user interface (GUI), was programmed using only the MATLAB language so that it can be used without additional library installation and configuration. The program runs in the same order as TET2DICOM and has been optimized to run on a personal computer in a GUI environment. A tetrahedron-based male international standard human phantom, MRCP-AM, was used to evaluate TET2DICOM-GUI. Conversion into a DICOM-RT dataset applicable in clinical practice in about one hour with a personal computer as a basis was confirmed. Also, the generated DICOM-RT dataset was confirmed to be effectively implemented in the radiotherapy planning system. The program developed in this study is expected to replace actual patient data in future studies.
Review Article 2024-03-31

Impact of Planning Target Volume Margins in Stereotactic Radiosurgery for Brain Metastasis: A Review

Emmanuel Fiagbedzi^1,2 , Francis Hasford¹ , Samuel Nii Tagoe¹

Progress in Medical Physics 2024; 35(1): 1-9
https://doi.org/10.14316/pmp.2024.35.1.1

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Margin inclusion or exclusion remains the most critical and controversial aspect of stereotactic radiosurgery (SRS) for metastatic brain tumors. This review aimed to examine the available literature on the impact of margins in SRS of brain metastasis and to assess the response of some medical physicists on the use of these margins. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses method was used to review articles published in PubMed, Embase, and Science Direct databases from January 2012 to December 2022 using the following keywords: planning target volume, brain metastasis, margin, and stereotactic radiosurgery. A simple survey consisting of five questions was completed by ten medical physicists with experience in SRS treatment planning. The results were analyzed using IBM SPSS Statistics version 26.0. Of the 1,445 articles identified, only 38 articles were chosen. Of these, eight papers were deemed relevant to the focus of this review. These papers showed an increase in the risk of radionecrosis, whereas differences in local control were variable as the margin increased. In the survey, the response rate to whether or not to use margins in SRS, a critical question, was 50%. Margin addition increases the risk of radio necrosis. The local control rate varies among treatment modalities and cannot be generalized. From the survey, no consensus was reached regarding the use of these margins. This calls for further deliberations among professionals directly involved in SRS.
Original Article 2022-12-31

Determination of Absorbed Dose for Gafchromic EBT3 Film Using Texture Analysis of Scanning Electron Microscopy Images: A Feasibility Study

So-Yeon Park

Progress in Medical Physics 2022; 33(4): 158-163
https://doi.org/10.14316/pmp.2022.33.4.158

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Purpose: We subjected scanning electron microscopic (SEM) images of the active layer of EBT3 film to texture analysis to determine the dose-response curve.
Methods: Uncoated Gafchromic EBT3 films were prepared for direct surface SEM scanning. Absorbed doses of 0–20 Gy were delivered to the film’s surface using a 6 MV TrueBeam STx photon beam. The film’s surface was scanned using a SEM under 100× and 3,000× magnification. Four textural features (Homogeneity, Correlation, Contrast, and Energy) were calculated based on the gray level co-occurrence matrix (GLCM) using the SEM images corresponding to each dose. We used R-square to evaluate the linear relationship between delivered doses and textural features of the film’s surface.
Results: C orrelation r esulted i n h igher l inearity a nd d ose-response c urve s ensitivity t han Homogeneity, Contrast, or Energy. The R-square value was 0.964 for correlation using 3,000× magnified SEM images with 9-pixel offsets. Dose verification was used to determine the difference between the prescribed and measured doses for 0, 5, 10, 15, and 20 Gy as 0.09, 1.96, −2.29, 0.17, and 0.08 Gy, respectively.
Conclusions: Texture analysis can be used to accurately convert microscopic structural changes to the EBT3 film’s surface into absorbed doses. Our proposed method is feasible and may improve the accuracy of film dosimetry used to protect patients from excess radiation exposure.
Original Article 2022-12-31

Proficiency Test for the Dosimetry Audit Service Provider

Chul-Young Yi , In Jung Kim , Jong In Park , Yun Ho Kim , Young Min Seong

Progress in Medical Physics 2022; 33(4): 72-79
https://doi.org/10.14316/pmp.2022.33.4.72

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Purpose: The proficiency test was conducted to assess the performance of the dosimetry audit service provider in the readout practice of the dose delivered to patients in medical institutions.
Methods: A certain amount of the absorbed dose to water for the high-energy X-ray from the medical linear accelerator (LINAC) installed in the Korea Research Institute of Standards and Science (KRISS) was delivered to the postal dose audit package given by the dosimetry audit service provider, in which the radio-photoluminescence (RPL) glass dosimeters were mounted. The dosimetry audit service provider read the RPL glass dosimeters and sent the readout dose value with its uncertainty to KRISS. The performance of the dosimetry audit service provider was evaluated based on the E_n number given in ISO/IEC 17043:2010.
Results: The evaluated E_n number was −0.954. Based on the ISO/IEC 17043, the performance of the dosimetry service provider is “satisfactory.”
Conclusions: As part of the conformity assessment, the KRISS performed the proficiency test over the postal dose audit practice run by the dosimetry audit service provider. The proficiency test is in line with confirming the traceability of the medical institutions to the primary standard of absorbed dose to the water of the KRISS and ensuring the confidence of the dosimetry audit service provider.
Original Article 2022-12-31

Development of a Breath Control Training System for Breath-Hold Techniques and Respiratory-Gated Radiation Therapy

Hyung Jin Choun¹ , Jung-in Kim^2,3,4 , Jong Min Park^2,3,4 , Jaeman Son^2,3,4

Progress in Medical Physics 2022; 33(4): 136-141
https://doi.org/10.14316/pmp.2022.33.4.136

Abstract

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Purpose: This study aimed to develop a breath control training system for breath-hold technique and respiratory-gated radiation therapy wherein the patients can learn breath-hold techniques in their convenient environment.
Methods: The breath control training system comprises a sensor device and software. The sensor device uses a loadcell sensor and an adjustable strap around the chest to acquire respiratory signals. The device connects via Bluetooth to a computer where the software is installed. The software visualizes the respiratory signal in near real-time with a graph. The developed system can signal patients through visual (software), auditory (buzzer), and tactile (vibrator) stimulation when breath-holding starts. A motion phantom was used to test the basic functions of the developed breath control training system. The relative standard deviation of the maxima of the emulated free breathing data was calculated. Moreover, a relative standard deviation of a breath-holding region was calculated for the simulated breath-holding data.
Results: The average force of the maxima was 487.71 N, and the relative standard deviation was 4.8%, while the average force of the breath hold region was 398.5 N, and the relative standard deviation was 1.8%. The data acquired through the sensor was consistent with the motion created by the motion phantom.
Conclusions: We have developed a breath control training system comprising a sensor device and software that allow patients to learn breath-hold techniques in their convenient environment.
Original Article 2022-12-31

Evaluation of Treatment Plan Quality between Magnetic Resonance-Guided Radiotherapy and Volumetric Modulated Arc Therapy for Prostate Cancer

Chang Heon Choi^1,2,3 , Jin Ho Kim^1,3 , Jaeman Son^1,2,3 , Jong Min Park^1,2,3,4 , Jung-in Kim^1,2,3

Progress in Medical Physics 2022; 33(4): 121-128
https://doi.org/10.14316/pmp.2022.33.4.121

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Purpose: T his s tudy e valuated t he q uality of plans based on magnetic resonance-guided radiotherapy (MRgRT) tri-Co-60, linac, and conventional linac-based volumetric modulated arc therapy (linac-VMAT) for prostate cancer.
Methods: Twenty patients suffering from prostate cancer with intermediate risk who were treated by MAT were selected. Additional treatment plans (primary and boost plans) were generated based on MRgRT-tri-Co-60 and MRgRT-linac. The planning target volume (PTV) of MRgRT-based plans was created by adding a 3 mm margin from the clinical target volume (CTV) due to high soft-tissue contrast and real-time motion imaging. On the other hand, the PTV of conventional linac was generated based on a 1 cm margin from CTV. The targets of primary and boost plans were prostate plus seminal vesicle and prostate only, respectively. All plans were normalized to cover 95% of the target volume by 100% of the prescribed dose. Dosimetric characteristics were evaluated for each of the primary, boost, and sum plans.
Results: For target coverage and conformity, the three plans showed similar results. In the sum plans, the average value of V_65Gy of the rectum of MRgRT-linac (2.62%±2.21%) was smaller than those of MRgRT tri-Co-60 (9.04%±3.01%) and linac-VMAT (9.73%±7.14%) (P<0.001). In the case of bladder, the average value of V_65Gy of MRgRT-linac was also smaller.
Conclusions: In terms of organs at risk sparing, MRgRT-linac shows the best value while maintaining comparable target coverage among the three plans.
Original Article 2022-12-31

Feasibility Test of Flat-Type Faraday Cup for Ultrahigh-Dose-Rate Transmission Proton Beam Therapy

Sang-il Pak¹ , Sungkoo Cho² , Seohyeon An^1,3 , Seonghoon Jeong¹ , Dongho Shin¹ , Youngkyung Lim¹ , Jong Hwi Jeong¹ , Haksoo Kim¹ , Se Byeong Lee¹

Progress in Medical Physics 2022; 33(4): 108-113
https://doi.org/10.14316/pmp.2022.33.4.108

Abstract

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Purpose: Proton therapy has been used for optimal cancer treatment by adapting its Bragg-peak characteristics. Recently, a tissue-sparing effect was introduced in ultrahigh-dose-rate (FLASH) radiation; the high-energy transmission proton beam is considered in proton FLASH therapy. In measuring high-energy/ultrahigh-dose-rate proton beam, Faraday Cup is considered as a dose-rate- independent measurement device, which has been widely studied. In this paper, the feasibility of the simply designed Faraday Cup (Poor Man’s Faraday Cup, PMFC) for transmission proton FLASH therapy is investigated.
Methods: In general, Faraday cups were used in the measurement of charged particles. The simply designed Faraday Cup and Advanced Markus ion chamber were used for high-energy proton beam measurement in this study.
Results: The PMFC shows an acceptable performance, including accuracy in general dosimetric tests. The PMFC has a linear response to the dose and dose rate. The proton fluence was decreased with the increase of depth until the depth was near the proton beam range. Regarding secondary particles backscatter from PMFC, the effect was negligible.
Conclusions: In this study, we performed an experiment to investigate the feasibility of PMFC for measuring high-energy proton beams. The PMFC can be used as a beam stopper and secondary monitoring system for transmission proton beam FLASH therapy.
Original Article 2022-12-31

Monte Carlo Investigation of Dose Enhancement due to Gold Nanoparticle in Carbon-12, Helium-4, and Proton Beam Therapy

Sang Hee Ahn

Progress in Medical Physics 2022; 33(4): 114-120
https://doi.org/10.14316/pmp.2022.33.4.114

Abstract

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Purpose: Particle beam therapy is advantageous over photon therapy. However, adequately delivering therapeutic doses to tumors near critical organs is difficult. Nanoparticle-aided radiation therapy can be used to alleviate this problem, wherein nanoparticles can passively accumulate at higher concentrations in the tumor tissue compared to the surrounding normal tissue. In this study, we investigate the dose enhancement effect due to gold nanoparticle (GNP) when Carbon-12, He-4, and proton beams are irradiated on GNP.
Methods: First, monoenergetic Carbon-12 and He-4 ion beams of energy of 283.33 MeV/u and 150 MeV/u, respectively, and a proton beam of energy of 150 MeV were irradiated on a water phantom of dimensions 30 cm×30 cm×30 cm. Subsequently, the secondary-particle information generated near the Bragg peak was recorded in a phase-space (phsp) file. Second, the obtained phsp file was scaled down to a nanometer scale to irradiate GNP of diameter 50 nm located at the center of a 4 µm×4 µm×4 µm water phantom. The dose enhancement ratio (DER) was calculated in intervals of 1 nm from the GNP surface.
Results: The DER of GNP computed at 1 nm from the GNP surface was 4.70, 4.86, and 4.89 for Carbon-12, He-4, and proton beams, respectively; the DER decreased rapidly with increasing distance from the GNP surface.
Conclusions: The results indicated that GNP can be used as radiosensitizers in particle beam therapy. Furthermore, the dose enhancement effect of the GNP absorbed by tumor cells can aid in delivering higher therapeutic doses.
Original Article 2022-12-31

Contribution of Microbleeds on Microvascular Magnetic Resonance Imaging Signal

Chang Hyun Yoo¹ , Junghwan Goh¹ , Geon-Ho Jahng²

Progress in Medical Physics 2022; 33(4): 88-100
https://doi.org/10.14316/pmp.2022.33.4.88

Abstract

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Purpose: Cerebral microbleeds are more susceptible than surrounding tissues and have been associated with a variety of neurological and neurodegenerative disorders that are indicative of an underlying vascular pathology. We investigated relaxivity changes and microvascular indices in the presence of microbleeds in an imaging voxel by evaluating those before and after contrast agent injection.
Methods: Monte Carlo simulations were run with a variety of conditions, including different magnetic field strengths (B₀), different echo times, and different contrast agents. ΔR2* and ΔR2 and microvascular indices were calculated with varying microvascular vessel sizes and microbleed loads.
Results: As B₀ and the concentration of microbleeds increased, ΔR2* and ΔR2 increased. ΔR2* increased, but ΔR2 decreased slightly as the vessel radius increased. When the vessel radius was increased, the vessel size index (VSI) and mean vessel diameter (mVD) increased, and all other microvascular indices except mean vessel density (Q) increased when the concentration of microbleeds was increased.
Conclusions: Because patients with neurodegenerative diseases often have microbleeds in their brains and VSI and mVD increase with increasing microbleeds, microbleeds can be altered microvascular signals in a voxel in the brain of a neurodegenerative disease at 3T magnetic resonance imaging.
Original Article 2022-12-31

Minimization of Treatment Time Using Partial-Arc Volumetric Modulated Arc Therapy with Bladder Filling Protocol for Prostate Cancer

Hojeong Lee¹ , Dong Woon Kim¹ , Ji Hyeon Joo^1,2 , Yongkan Ki^1,2 , Wontaek Kim^2,3 , Dahl Park³ , Jiho Nam³ , Dong Hyeon Kim^2,3 , Hosang Jeon¹

Progress in Medical Physics 2022; 33(4): 101-107
https://doi.org/10.14316/pmp.2022.33.4.101

Abstract

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Purpose: Radiotherapy after bladder filling protocol (BFP) is known to enhance treatment quality and reduce side effects in prostate cancer, a common male solid cancer globally. However, due to the need to hold back urine during treatment, patients frequently complain of discomfort, and treatment is frequently suspended when patients urinate during treatment and urine penetrates the treatment device, causing malfunction. Therefore, the effect of minimizing treatment time when partial-arc volumetric modulated arc therapy (VMAT) was used instead of full-arc was assessed in this study.
Methods: A total of 70 plans were created in 10 patients using 7 different arc sizes, and the treatment time for each plan was calculated.
Results: Reduced arc size by half resulted in a 54.4% decrease in mean treatment duration, with a proportional tendency observed. Furthermore, the effect of VMAT arc size reduction on target dose homogeneity was significantly limited, and the effect on surrounding organs at risk (OAR) was negligible. It should be noted, however, that when the arc size decreases by >40%, the dose increases in the area without OAR around the target.
Conclusions: The results of this study demonstrated that partial-arc VMAT for enhancing treatment convenience and efficacy of prostate cancer patients undergoing BFP can achieve a considerable reduction in treatment time while preserving treatment quality, and it is expected to be useful for partial-arc VMAT plan design and implementation in practice.
Original Article 2022-12-31

Dosimetric Evaluation of Synthetic Computed Tomography Technique on Position Variation of Air Cavity in Magnetic Resonance-Guided Radiotherapy

Hyeongmin Jin^1,2 , Hyun Joon An¹ , Eui Kyu Chie^1,2,3 , Jong Min Park^1,2,3 , Jung-in Kim^1,2

Progress in Medical Physics 2022; 33(4): 142-149
https://doi.org/10.14316/pmp.2022.33.4.142

Abstract

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Purpose: This study seeks to compare the dosimetric parameters of the bulk electron density (ED) approach and synthetic computed tomography (CT) image in terms of position variation of the air cavity in magnetic resonance-guided radiotherapy (MRgRT) for patients with pancreatic cancer.
Methods: This study included nine patients that previously received MRgRT and their simulation CT and magnetic resonance (MR) images were collected. Air cavities were manually delineated on simulation CT and MR images in the treatment planning system for each patient. The synthetic CT images were generated using the deep learning model trained in a prior study. Two more plans with identical beam parameters were recalculated with ED maps that were either manually overridden by the cavities or derived from the synthetic CT. Dose calculation accuracy was explored in terms of dose-volume histogram parameters and gamma analysis.
Results: The D_95% averages were 48.80 Gy, 48.50 Gy, and 48.23 Gy for the original, manually assigned, and synthetic CT-based dose distributions, respectively. The greatest deviation was observed for one patient, whose D_95% to synthetic CT was 1.84 Gy higher than the original plan.
Conclusions: The variation of the air cavity position in the gastrointestinal area affects the treatment dose calculation. Synthetic CT-based ED modification would be a significant option for shortening the time-consuming process and improving MRgRT treatment accuracy.
Original Article 2022-12-31

Monte Carlo Algorithm-Based Dosimetric Comparison between Commissioning Beam Data across Two Elekta Linear Accelerators with Agility^TM MLC System

Geum Bong Yu¹ , Chang Heon Choi^1,2,3 , Jung-in Kim^1,2,3 , Jin Dong Cho^1,2 , Euntaek Yoon⁴ , Hyung Jin Choun^2,4 , Jihye Choi^5,6 , Soyeon Kim^5,6 , Yongsik Kim⁶ , Do Hoon Oh⁷ , Hwajung Lee⁷ , Lee Yoo⁷ , Minsoo Chun^3,7

Progress in Medical Physics 2022; 33(4): 150-157
https://doi.org/10.14316/pmp.2022.33.4.150

Abstract

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Purpose: Elekta synergy^® was commissioned in the Seoul National University Veterinary Medical Teaching Hospital. Recently, Chung-Ang University Gwang Myeong Hospital commissioned Elekta Versa HD^TM. The beam characteristics of both machines are similar because of the same Agility^TM MLC Model. We compared measured beam data calculated using the Elekta treatment planning system, Monaco^®, for each institute.
Methods: Beam of the commissioning Elekta linear accelerator were measured in two independent institutes. After installing the beam model based on the measured beam data into the Monaco^®, Monte Carlo (MC) simulation data were generated, mimicking the beam data in a virtual water phantom. Measured beam data were compared with the calculated data, and their similarity was quantitatively evaluated by the gamma analysis.
Results: We compared the percent depth dose (PDD) and off-axis profiles of 6 MV photon and 6 MeV electron beams with MC calculation. With a 3%/3 mm gamma criterion, the photon PDD and profiles showed 100% gamma passing rates except for one inplane profile at 10 cm depth from VMTH. Gamma analysis of the measured photon beam off-axis profiles between the two institutes showed 100% agreement. The electron beams also indicated 100% agreement in PDD distributions. However, the gamma passing rates of the off-axis profiles were 91%–100% with a 3%/3 mm gamma criterion.
Conclusions: The beam and their comparison with MC calculation for each institute showed good performance. Although the measuring tools were orthogonal, no significant difference was found.
Original Article 2024-03-31

Evaluations of a Commercial CLEANBOLUS-WHITE for Clinical Application

Geum Bong Yu^1,2 , Jung-in Kim^1,2 , Jaeman Son^1,2

Progress in Medical Physics 2024; 35(1): 10-15
https://doi.org/10.14316/pmp.2024.35.1.10

Abstract

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Purpose: This study aimed to comprehensively investigate the diverse characteristics of a novel commercial bolus, CLEANBOLUS-WHITE (CBW), to ascertain its suitability for clinical application.
Methods: The evaluation of CBW encompassed both physical and biological assessments. Physical parameters such as mass density and shore hardness were measured alongside analyses of element composition. Biological evaluations included assessments for skin irritation and cytotoxicity. Dosimetric properties were examined by calculating surface dose and beam quality using a treatment planning system (TPS). Additionally, doses were measured at maximum and reference depths, and the results were compared with those obtained using a solid water phantom. The effect of air gap on dose measurement was also investigated by comparing measured doses on the RANDO phantom, under the bolus, with doses calculated from the TPS.
Results: Biological evaluation confirmed that CBW is non-cytotoxic, nonirritant, and non-sensitizing. The bolus exhibited a mass density of 1.02 g/cm³ and 14 shore 00. Dosimetric evaluations revealed that using the 0.5 cm CBW resulted in less than a 1% difference compared to using the solid water phantom. Furthermore, beam quality calculations in the TPS indicated increased surface dose with the bolus. The air gap effect on dose measurement was deemed negligible, with a difference of approximately 1% between calculated and measured doses, aligning with measurement uncertainty.
Conclusions: CBW demonstrates outstanding properties for clinical utilization. The dosimetric evaluation underscores a strong agreement between calculated and measured doses, validating its reliability in both planning and clinical settings.
Original Article 2023-12-31

Dosimetric Comparison of Three-Dimensional Conformal, Intensity-Modulated Radiotherapy, Volumetric Modulated Arc Therapy, and Dynamic Conformal Arc Therapy Techniques in Prophylactic Cranial Irradiation

Ismail Faruk Durmuş¹ , Dursun Esitmez² , Guner Ipek Arslan¹ , Ayse Okumus¹

Progress in Medical Physics 2023; 34(4): 41-47
https://doi.org/10.14316/pmp.2023.34.4.41

Abstract

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Purpose: This study aimed to dosimetrically compare the technique of three-dimensional conformal radiotherapy (3D CRT), which is a traditional prophylactic cranial irradiation method, and the intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) techniques used in the last few decades with the dynamic conformal arc therapy (DCAT) technique.
Methods: The 3D CRT, VMAT, IMRT, and DCAT plans were prepared with 25 Gy in 10 fractions in a Monaco planning system. The target volume and the critical organ doses were compared. A comparison of the body V₂, V₅, and V₁₀ doses, monitor unit (MU), and beam on-time values was also performed.
Results: In planned target volume of the brain (PTV_Brain), the highest D99 dose value (P<0.001) and the most homogeneous (P =0.049) dose distribution according to the heterogeneity index were obtained using the VMAT technique. In contrast, the lowest values were obtained using the 3D CRT technique in the body V₂, V₅, and V₁₀ doses. The MU values were the lowest when DCAT (P =0.001) was used. These values were 0.34% (P =0.256) lower with the 3D CRT technique, 66% (P =0.001) lower with IMRT, and 72% (P =0.001) lower with VMAT. The beam on-time values were the lowest with the 3D CRT planning (P<0.001), 3.8% (P =0.008) lower than DCAT, 65% (P =0.001) lower than VMAT planning, and 76% (P =0.001) lower than IMRT planning.
Conclusions: Without sacrificing the homogeneous dose distribution and the critical organ doses in IMRTs, three to four times less treatment time, less low-dose volume, less leakage radiation, and less radiation scattering could be achieved when the DCAT technique is used similar to conventional methods. In short, DCAT, which is applicable in small target volumes, can also be successfully planned in large target volumes, such as the whole-brain.
Review Article 2024-06-30

Motion Management and Image-Guided Technique in Photon Radiation Therapy: A Review of an Advanced Technology

Jin Jegal^1,2 , Hyojun Park^1,2 , Seonghee Kang^1,2,3,4 , Chang Heon Choi^1,2,3,4 , Jung-in Kim^1,2,3,4

Progress in Medical Physics 2024; 35(2): 21-35
https://doi.org/10.14316/pmp.2024.35.2.21

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Herein, we provide a concise review of the critical role of motion management in radiation therapy, with a focus on photon radiation therapy, real-time control of respiratory motion, and image-guided radiation therapy (IGRT) in lung stereotactic body radiation therapy (SBRT). The dynamic nature of human anatomy, particularly in regions prone to movement such as the thoracic and abdominal areas, poses significant challenges in accurately targeting tumors during radiation therapy. This review explores the implications of organ and tumor motion, emphasizing the necessity for precise treatment delivery. We assess the advancements in four-dimensional (4D) imaging techniques such as 4D computed tomography, which provide time-resolved images for enhanced treatment planning. The review highlights various motion management strategies, including motionencompassing methods, respiratory-gating, breath-hold techniques, and real-time tumor tracking, discussing their implementation and impact on treatment efficacy. The role of IGRT in lung SBRT is particularly emphasized, showcasing how real-time imaging and advanced targeting techniques enhance the precision of high-dose radiation delivery while minimizing exposure to surrounding healthy tissues. This comprehensive review aims to underscore the significance of integrating motion management in radiation therapy, highlighting its pivotal role in improving treatment accuracy, reducing toxicity, and ultimately enhancing patient outcomes in cancer care.
Original Article 2023-12-31

Dosimetric Analysis of Lung Stereotactic Body Radiotherapy Using Halcyon Linear Accelerator

Shinhaeng Cho¹ , Ick Joon Cho¹ , Yong Hyub Kim¹ , Jea-Uk Jeong² , Mee Sun Yoon² , Taek-Keun Nam² , Sung-Ja Ahn² , Ju-Young Song²

Progress in Medical Physics 2023; 34(4): 48-54
https://doi.org/10.14316/pmp.2023.34.4.48

Abstract

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Purpose: In this study, the dosimetric characteristics of lung stereotactic body radiotherapy (SBRT) plans using the new Halcyon system were analyzed to assess its suitability.
Methods: We compared the key dosimetric parameters calculated for the Halcyon SBRT plans with those of a conventional C-arm linear accelerator (LINAC) equipped with a high-definition multileaf collimator (HD-MLC)—Trilogy Tx. A total of 10 patients with non-small-cell lung cancer were selected, and all SBRT plans were generated using the RapidArc technique.
Results: Trilogy Tx exhibited significant superiority over Halcyon in terms of target dose coverage (conformity index, homogeneity index, D_{0.1 cc}, and D_95%) and dose spillage (gradient). Trilogy Tx was more efficient than Halcyon in the lung SBRT beam delivery process in terms of the total number of monitor units, modulation factor, and beam-on time. However, it was feasible to achieve a dose distribution that met SBRT plan requirements using Halcyon, with no significant differences in satisfying organs at risk dose constraints between both plans.
Conclusions: Results confirm that Halcyon is a viable alternative for performing lung SBRT in the absence of a LINAC equipped with HD-MLC. However, extra consideration should be taken in determining whether to use Halcyon when the planning target volume setting is enormous, as in the case of significant tumor motions.
Original Article 2022-12-31

Effect of Bead Device Diameter on Z-Resolution Measurement in Tomosynthesis Images: A Simulation Study

Ryohei Fukui¹ , Miho Numata² , Saki Nishioka² , Ryutarou Matsuura¹ , Katsuhiro Kida¹ , Sachiko Goto¹

Progress in Medical Physics 2022; 33(4): 63-71
https://doi.org/10.14316/pmp.2022.33.4.63

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Purpose: To clarify the relationship between the diameter of the simulated bead and the Z-resolution of the tomosynthesis image.
Methods: A simulated bead was placed on a 1,024×1,024×1,024-pixel base image. The diameters were set to 0.025, 0.05, 0.1, 0.2, 0.3, 0.7, 1.0, and 1.3 mm. A bead was placed at the center of the base image and projected at a simulated X-ray angle range of ±45° to obtain a projected image. A region of interest was placed at the center of the bead image and the slice sensitivity profile (SSP) was obtained by acquiring pixel values in the z-direction. The full width at half maximum of the SSP was defined as the Z-resolution and the frequency response was obtained by the 1-D Fourier transform of the SSP.
Results: Z-resolution increased with increasing bead diameter. However, there was no change in Z-resolution between 0.025 and 0.1 mm. The frequency response was similar to that of the Z-resolution, with a significant difference between 0.1 and 0.2 mm diameter.
Conclusions: Z-resolution is dependent on the diameter of the bead, which should be selected considering the pixel size of the tomosynthesis image.
Corrigendum 2022-12-31

Corrigendum: Assessing Commercial CLEANBOLUS Based on Silicone for Clinical Use

Jaeman Son^1,2 , Seongmoon Jung^1,2 , Jong Min Park^1,2,3,4 , Chang Heon Choi^1,2,3 , Jung-in Kim^1,2,3

Progress in Medical Physics 2022; 33(4): 180-180
https://doi.org/10.14316/pmp.2022.33.4.180

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Corrigendum 2023-03-31

Corrigendum: Image Guided Radiation Therapy

Ui-Jung Hwang¹ , Byung Jun Min² , Meyoung Kim³ , Ki-Hwan Kim¹

Progress in Medical Physics 2023; 34(1): 14-14
https://doi.org/10.14316/pmp.2023.34.1.14

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Letter to the Editor 2024-03-31

Formulation of a New E_n Score in the Proficiency Test

Chul-Young Yi , In Jung Kim , Jong In Park , Yun Ho Kim , Young Min Seong

Progress in Medical Physics 2024; 35(1): 16-19
https://doi.org/10.14316/pmp.2024.35.1.16

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A new E_n score of the proficiency test (PT) is formulated; it is applicable when a correlation exists between the reference and participant’s values. Based on the uncertainty propagation rule given in ISO/IEC Guide 98-3 (GUM:1995), the E_n score covering the correlation case is newly developed for the PT. The new E_n score will be applied in a future PT organized by the Korea Research Institute of Standards and Science (KRISS) dosimetry team. The new E_n score will enhance measurement traceability and contribute to improving the quality management system of participants in the KRISS PT by avoiding performance underestimation.