• Progress in Medical Physics
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• v.24 no.1
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• pp.1-24
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• 2013

As image-guided radiation therapy (IGRT) has been commonly used for more accurate patient setup and monitoring tumor movement during radiation therapy, the necessity for management of imaging dose is increased. However, it has not been an interest issue to radiation therapy communities because the imaging dose is much lower than the therapeutic dose. However, since the cumulative dose from 4DCT and repeated imaging for daily setup verificationin would not be ignorable, appropriate dose management based on ALARA (As Low As Reasonably Achievable) principle is required. In this study, we aimed that (1) survey on imaging equipments and modalities used for IGRT, (2) estimation of IGRT imaging dose depending on treatment types and equipments, (3) collecting data of effective dose on treatment sites from each equipment and imaging protocol, and thus finally provide guideline for imaging dose reduction and optimization.

• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.3
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• pp.290-295
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• 2011

During tooth formation, tooth development can be affected by physical action or metabolic changes around dental follicle. Especially trauma to primary dentition is the most representative physical factor that can cause development disorders of succedaneous tooth. Enamel hypoplasia and crown discoloration of succedaneous tooth are common complications of trauma. And impaction, ectopic eruption, arrest of root formation and root dilaceration of succedaneous tooth are rare. In this case, a 6-year and 5-month-old female patient visited for dental evaluation after trauma. She was diagnosed with alveolar bone fracture near upper front teeth, extrusion of the upper right and left primary central incisors, intrusion of the upper right primary lateral incisor, and palatal luxation of the upper left primary lateral incisor. Upper right and left primary central incisors with severe mobility were extracted, with gingival suture on the day of the visit. During 24 months check up, root dilacerations were found near the cemento enamel junction in the upper lateral incisors and arrests of root formation were found on the coronal 1/3 of the root in the upper central incisors. Although alveolar bone fracture is rare type of trauma in children, a thorough examination of alveolar bone is essential for prognosis and following treatment in patients with trauma.

• Progress in Medical Physics
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• v.20 no.4
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• pp.269-276
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• 2009

Radiation treatment techniques using photon beam such as three-dimensional conformal radiation therapy (3D-CRT) as well as intensity modulated radiotherapy treatment (IMRT) demand accurate dose calculation in order to increase target coverage and spare healthy tissue. Both jaw collimator and multi-leaf collimators (MLCs) for photon beams have been used to achieve such goals. In the Pinnacle3 treatment planning system (TPS), which we are using in our clinics, a set of model parameters like jaw collimator transmission factor (JTF) and MLC transmission factor (MLCTF) are determined from the measured data because it is using a model-based photon dose algorithm. However, model parameters obtained by this auto-modeling process can be different from those by direct measurement, which can have a dosimetric effect on the dose distribution. In this paper we estimated JTF and MLCTF obtained by the auto-modeling process in the Pinnacle3 TPS. At first, we obtained JTF and MLCTF by direct measurement, which were the ratio of the output at the reference depth under the closed jaw collimator (MLCs for MLCTF) to that at the same depth with the field size $10{\times}10\;cm^2$ in the water phantom. And then JTF and MLCTF were also obtained by auto-modeling process. And we evaluated the dose difference through phantom and patient study in the 3D-CRT plan. For direct measurement, JTF was 0.001966 for 6 MV and 0.002971 for 10 MV, and MLCTF was 0.01657 for 6 MV and 0.01925 for 10 MV. On the other hand, for auto-modeling process, JTF was 0.001983 for 6 MV and 0.010431 for 10 MV, and MLCTF was 0.00188 for 6 MV and 0.00453 for 10 MV. JTF and MLCTF by direct measurement were very different from those by auto-modeling process and even more reasonable considering each beam quality of 6 MV and 10 MV. These different parameters affect the dose in the low-dose region. Since the wrong estimation of JTF and MLCTF can lead some dosimetric error, comparison of direct measurement and auto-modeling of JTF and MLCTF would be helpful during the beam commissioning.

• Progress in Medical Physics
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• v.21 no.3
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• pp.253-260
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• 2010

Most brachytherapy treatment planning systems employ a dosimetry formalism based on the AAPM TG-43 report which does not appropriately consider tissue heterogeneity. In this study we aimed to set up a simple Monte Carlo-based intracavitary high-dose-rate brachytherapy (IC-HDRB) plan verification platform, focusing particularly on the robustness of the direct Monte Carlo dose calculation using material and density information derived from CT images. CT images of slab phantoms and a uterine cervical cancer patient were used for brachytherapy plans based on the Plato (Nucletron, Netherlands) brachytherapy planning system. Monte Carlo simulations were implemented using the parameters from the Plato system and compared with the EBT film dosimetry and conventional dose computations. EGSnrc based DOSXYZnrc code was used for Monte Carlo simulations. Each $^{192}Ir$ source of the afterloader was approximately modeled as a parallel-piped shape inside the converted CT data set whose voxel size was $2{\times}2{\times}2\;mm^3$. Bracytherapy dose calculations based on the TG-43 showed good agreement with the Monte Carlo results in a homogeneous media whose density was close to water, but there were significant errors in high-density materials. For a patient case, A and B point dose differences were less than 3%, while the mean dose discrepancy was as much as 5%. Conventional dose computation methods might underdose the targets by not accounting for the effects of high-density materials. The proposed platform was shown to be feasible and to have good dose calculation accuracy. One should be careful when confirming the plan using a conventional brachytherapy dose computation method, and moreover, an independent dose verification system as developed in this study might be helpful.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.3
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• pp.341-347
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• 2003

Smith-Magenis syndrome (SMS) is a clinically recognizable multiple congenital anomaly and mental retardation syndrome caused by an interstitial deletion of chromosome 17 p11.2. Physical features include short stature, characteristic facial appearance: flattened mid-face, down-turned mouth, prominent and often rosy cheeks; prominent jaw in older children and adults, chronic ear infections, hearing impairment, eye problems, including: strabismus (an eye which turns in or out) and myopia (nearsightedness), hoarse voice, short fingers and toes, heart defects or murmurs, problems related to the urinary system, scoliosis (curvature of the spine), an unusual gait (walking pattern), and decreased sensitivity to pain. Behavioral and developmental characteristics include speech delay and articulation problems, developmental delay, learning disability, mental retardation, hyperactivity, self-injury, including: head banging; hand biting; picking at skin, sores and nails; pulling off finger- and toenails; inserting foreign objects into ears, nose, or other body orifices, explosive outbursts, prolonged tantrums, destructive and aggressive behavior, excitability, arm hugging or hand squeezing when excited. This report is the case of a Korean 3-year-3-month old male with Smith-Magenis syndrome referred from local clinic for the treatment of dental caries. The patient was treated by physical restraint after prophylatic administration of antibiotic(Amoxacillin 50mg/kg).

• Physical Therapy Korea
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• v.20 no.1
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• pp.18-27
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• 2013

The purpose of this study was to compare the ring lock type knee-ankle-foot orthosis (KAFO) with newly developed 4-bar linkage KAFO on the gait characteristics of persons with poliomyelitis clinically. This 4-bar linkage is the stance control type KAFO which provide the stability during stance phase and knee flexion during swing phase. Two subjects participated in this study voluntarily. We provided the customized 4-bar linkage KAFO then asked the subjects to walk in level surface and stairs under the two different KAFO conditions. The characteristics of gait in the persons with poliomyelitis were evaluated using a 3D motion analysis system and force plate. Additionally 6 minute walk test for physiological cost index were conducted using pulse oximeter to measure the energy consumption. In the results of this study, the differences of 4-bar linkage KAFO compared with ring lock type KAFO are as follows: (1) Walking speed, stride length, and step length on level increased in subjects, (2) The gait symmetry was improved by generated knee flexion and decreased pelvic external rotation on level and stairs walking, (3) Decreased vertical excursion of center of mass and pelvic elevation during swing phase was decreased on level, (4) Knee extension moment, hip flexion moment, hip and knee internal rotation moment of non-braced limb were decreased on level walking, (5) Walking speed in 6-minute walk test was increased and physiological cost index was decreased. These findings indicate that 4-bar linkage KAFO compared with ring lock type KAFO is effective in enhancing pattern, endurance, and energy consumption in level surface and stairs walking.

• Progress in Medical Physics
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• v.23 no.4
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• pp.234-238
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• 2012

A tumor on the eyelid is often treated using a high-energy electron beam, with a metallic eye shield inserted between the eyelid and the eyeball to preserve the patient's sight. Pretreatment quality assurance of the inner eyelid dose on the metallic shield requires a very small dosimetry tool. For enhanced accuracy, a flexible device fitting the curved interface between the eyelid and the shield is also required. The radiochromic film is the best candidate for this device. To measure the doses along the curved interface and small area, a 3-mm-wide strip of EBT2 film was inserted between the phantom eyelid and the shield. After irradiation with 6 MeV electron beams, the film was evaluated for the dose profile. An acrylic eye shield of the same size as the real eye shield was machined, and CT images free from metal artifacts were obtained. Monte Carlo simulation was performed on the CT images, taking into account eye shield material, such as tungsten, aluminum, and steel. The film-based interface dose distribution agreed with the MC calculation within 2.1%. In the small (millimeter scale) and curved region, radiochromic film dosimetry promises a satisfactory result with easy handling.

• Progress in Medical Physics
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• v.21 no.3
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• pp.291-297
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• 2010

This study examined the dosimetric influence of implanted gold markers in proton therapy and the effects of their positions in the spread-out Bragg peak (SOBP) proton beam. The implanted cylindrical gold markers were 3 mm long and 1.2 mm in diameter. The dosimetric influence of the gold markers was determined with markers at various locations in a proton-beam field. Spatial dose distributions were measured using a three-dimensional moving water phantom and a stereotactic diode detector with an effective diameter of 0.5 mm. Also, a film dosimetry was performed using Gafchromic External Beam Treatment (EBT) film. The GEANT4 simulation toolkit was used for Monte-Carlo simulations to confirm the measurements and to construct the dose-volume histogram with implanting markers. Motion data were obtained from the portal images of 10 patients to investigate the effect of organ motions on the dosimetric influence of markers in the presence of a rectal balloon. The underdosed volume due to a single gold marker, in which the dose was less than 95% of a prescribed amount, was 0.15 cc. The underdosed volume due to the presence of a gold marker is much smaller than the target volume. However, the underdosed volume is inside the gross tumor volume and is not smeared out due to translational prostate motions. The positions of gold markers and the conditions of the proton-beam field give different impacts on the dose distribution of a target with implanted gold markers, and should be considered in all clinical proton-based therapies.

• Radiation Oncology Journal
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• v.20 no.2
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• pp.186-192
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• 2002

Purpose : Measurement of transmission dose is useful for in vivo dosimetry. In this study, previous algorithm for estimation of transmission dose was modified for use in cases with tissue deficit. Materials and Methods : The beam data was measured with flat solid phantom in various conditions of tissue deficit. New algorithm for correction of transmission dose for tissue deficit was developed by physical reasoning. The algorithm was tested in experimental settings with irregular contours mimicking breast cancer patients using multiple sheets of solid phantoms. Results : The correction algorithm for tissue deficit could accurately reflect the effect of tissue deficit with errors within ${\pm}1.0\%$ in most situations and within ${\pm}3.0\%$ in experimental settings with irregular contours mimicking breast cancer treatment set-up. Conclusion : Developed algorithm could accurately reflect the effect of tissue deficit and irregularly shaped body contour on transmission dosimetry.

• The Journal of Korean Physical Therapy
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• v.24 no.5
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• pp.377-382
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• 2012

Purpose: The purpose of this qualitative study was to understand the application of clinical reasoning throughout clinical and therapeutic knowledge of clinical pediatric physical therapists under physician prescriptions. Methods: Purposive sampling techniques were used in selection of nine clinical pediatric physical therapists in South Korea. Open and semi structured interviews were conducted, and were thoroughly examined and reviewed, followed by analysis of the clinical reasoning portion. Results: Pediatric physical therapists have been influenced by information gathering, physical function and evaluation of their patients, hypothesis-orientation, and re-evaluation and self-monitoring. Novice physical therapists were more dependent on physician prescriptions and parent's hope than the result of their own evaluation and critical pathway. Middle experienced pediatric physical therapists were more dependent on rapport with children and their parents. Highly experienced pediatric physical therapists were more reliant on hypothesis-orientation and self-monitoring. As reports on clinical experience of pediatric physical therapists have accumulated, clinical reasoning of pediatric physical therapists has been influenced by their experience, such as education, clinical pathology conference, their own clinical experience and rapport with patients and their parents than physicians' prescriptions. Conclusion: The findings of the current study are generally consistent with existing research on clinical reasoning. The results of the current study may be used by educators for enhancement of clinical reasoning abilities and knowledge of students or novices as well as development of a guide for use by suitable novices or students, and could provide important information for use in physical therapy practice and research.