김찬형 교수

Radiation dose enhancement by injection of a high atomic number (Z) material into tumor volumes has been studied for various radiation sources and different concentrations of gold nanoparticles. Brachytherapy employs low energy photons of less than 0.5 MeV, which indeed is the optimal energy range for radiation dose enhancement by introduction of high-Z material. The present study uses the MCNPXTM code to estimate the dose enhancement by gold nanoparticles for the four common brachytherapy sourc

In the present study, we established a comprehensive dataset of dose coefficients (DCs) of the new meshtypeICRP reference computational phantoms (MRCPs) for idealized external exposures of photons andelectrons with the Geant4 code. Subsequently, the DCs for the nine organs/tissues, calculated for theirthin radiosensitive target regions, were compared with the values calculated by averaging the absorbeddoses over the entire organ/tissue regions to observe the influence of the thin sensitive regio

Recently, the International Commission on Radiological Protection (ICRP) has developed the Mesh-type Reference Computational Phantoms (MRCPs) for adult male and female to overcome the limitations of the current Voxel-type Reference Computational Phantoms (VRCPs) described in ICRP Publication 110 due to the limited voxel resolutions and the nature of voxel geometry. In our previous study, the MRCPs were used to calculate the dose coefficients (DCs) for idealized external exposures of photons and

In this research, a multi-slit prompt-gamma camera was developed to locate the distal dose falloff of theproton beam spots in spot scanning proton therapy. To see the performance of the developed camera,therapeutic proton beams were delivered to a solid plate phantom and then the prompt gammas fromthe phantom were measured using the camera. Our results show that the camera locates the 90% distaldose falloff (¼ d90%), within about 2e3 mm of error for the spots which are composed 3.8 108 protonsor

If the proton therapy modality allowing excellent dose localization to the tumor volume and negligible exit dose in the patient is to be taken advantage of, a proper dosimetry system is required. We have recently designed a prompt-gamma scanning system to measure the proton range in situ by using a Monte Carlo technique employing MCNPX, FLUKA, and SabrinaTM. The gamma scanning system was designed to measure only the right-angled prompt gammas passing through a narrow collimation hole in order to

Purpose: Adjuvant radiotherapy of breast cancer using a photon tangential field incurs a risk of late heart and lung toxicity. The use of free breathing (FB), expiration breath hold (EBH), and deep inspiration breath hold (DIBH) during tangential breast radiotherapy as a means of reducing irradiated lung and heart volume was evaluated. Methods: In 10 women with left-sided breast cancer (mean age, 44 years) post-operative computed tomography (CT) scanning was done under different respiratory cond

For radiological protection from exposure to ionizing radiation, in which a population-averaged dose evaluation is used, establishing a system of reference anatomical and physiological data for a specific population of interest is important. Some studies were done in the past to establish Korean reference data; however, the data provided the mass values only for a limited number of organs/tissues. In addition, the standing height and total body mass are based on ~ 20-year-old data. In the presen

In the present study, we developed a position-sensitive NaI(Tl) scintillation detector module for use in the development of a large-area Compton camera. The developed detector module employs a large (i.e., 27 × 27 × 2 cm3) monolithic NaI(Tl) scintillator coupled with a closely packed array of 6 × 6 square PMTs. A multiplexer-based signal processing circuit and a data acquisition system were developed to estimate the interaction position in the scintillator from the signals of the PMTs by using t

The counting efficiencies obtained using anthropomorphic physical phantoms are generally used inwhole-body counting measurements to determine the level of internal contamination in the body. Geometrical discrepancies between phantoms and measured individuals affect the counting efficiency,and thus, considering individual physical characteristics is crucial to improve the accuracy of activityestimates. In the present study, the counting efficiencies of whole-body counting measurements werecalcula

Recently a prototype prompt gamma scanner system, named the PGS (prompt gamma scanner), was constructed and used to demonstrate that there is a clear correlation between prompt gamma distribution and the range of the proton beam in a patient. However, the PGS system requires a scanning process to obtain the prompt gamma distribution; consequently, it cannot be used in ``spot scanning'', in which the proton beam is continuously moving during treatment. The present Monte Carlo study explored the f

As part of the ICRP Task Group 103 project, we developed ten thyroid models for the pediatric mesh-type reference computational phantoms (MRCPs). The thyroid is not only a radiosensitive target organ needed for effective dose calculation but an important source region particularly for radioactive iodines. The thyroid models for the pediatric MRCPs were constructed by converting those of the pediatric voxel-type reference computational phantoms (VRCPs) in ICRP Publication 143 to a high-quality me

In the present study, iodine-131 S values (rT ) thyroid) were calculated for 30 target organs and tissuesusing the most recently developed Korean reference computational phantoms. The calculated S valueswere then compared with those of the International Commission on Radiological Protection (ICRP)reference computational phantoms to investigate the dosimetric impact of the Korean S values againstthose of the ICRP reference phantoms. The results showed significant differences in the S values due t

International Commission on Radiological Protection (ICRP) recently developed the adult and pediatric meshtype reference computational phantoms (MRCPs) in high-quality/fidelity mesh format, featuring high deformability into various body sizes and poses. Utilizing this feature, the adult MRCPs-based body-size-dependent phantom library was developed for individualized dosimetry. To complete the full phantom library set, the present study produced the pediatric-MRCPs-based body-size-dependent pedia

In proton therapy, a highly conformal proton dose can be delivered to the tumor by means of the steepdistal dose penumbra at the end of the beam range. The proton beam range, however, is highly sensitiveto range uncertainty, which makes accurately locating the proton range in the patient difficult. In-vivorange verification is a method to manage range uncertainty, one of the promising techniques beingprompt gamma imaging (PGI). In earlier studies, we proposed gamma electron vertex imaging (GEVI)

To enhance skeletal dosimetry in conjunction with the adult mesh-type reference Korean phantoms (MRKPs), Korean/Asian photon fluence-to-skeletal dose response functions (DRFs) were established utilizing an updated version of micro-CT-based detailed bone models from Tsinghua University. These bone models were incorporated into the MRKPs using the parallel geometry feature of Geant4. We calculated bone-site-specific electron absorbed fractions and used them to generate DRFs, following a similar me