• Progress in Medical Physics
• /
• v.29 no.4
• /
• pp.137-142
• /
• 2018

This study aimed to evaluate and verify a process for correcting the extended source-to-imager distance (SID) in portal dosimetry (PD). In this study, eight treatment plans (four volumetric modulated arc therapy and four intensity-modulated radiation therapy plans) at different treatment sites and beam energies were selected for measurement. A Varian PD system with portal dose image prediction (PDIP) was used for the measurement and verification. To verify the integrity of the plan, independent measurements were performed with the MapCHECK device. The predicted and measured fluence were evaluated using the gamma passing rate. The output ratio was defined as the ratio of the absolute dose of the reference SID (100 cm) to that of each SID (120 cm or 140 cm). The measured fluence for each SID was absolutely and relatively compared. The average SID output ratios were 0.687 and 0.518 for 120 SID and 140 SID, respectively; the ratio showed less than 1% agreement with the calculation obtained by using the inverse square law. The resolution of the acquired EPIDs were 0.336, 0.280, and 0.240 for 100, 120, and 140 SID, respectively. The gamma passing rates with PD and MapCHECK exceeded 98% for all treatment plans and SIDs. When autoalignment was performed in PD, the X-offset showed no change, and the Y-offset decreased with increasing SID. The PD-generated PDIP can be used for extended SID without additional correction.

• Progress in Medical Physics
• /
• v.25 no.4
• /
• pp.210-217
• /
• 2014

This study investigated the dosimetric effects of different dose calculation algorithm for lung stereotactic ablative radiotherapy (SABR) using flattening filter-free (FFF) beams. A total of 10 patients with lung cancer who were treated with SABR were evaluated. All treatment plans were created using an Acuros XB (AXB) of an Eclipse treatment planning system. An additional plans for comparison of different alagorithm recalcuated with anisotropic analytic algorithm (AAA) algorithm. To address both algorithms, the cumulative dose-volume histogram (DVH) was analyzed for the planning target volume (PTV) and organs at risk (OARs). Technical parameters, such as the computation times and total monitor units (MUs), were also evaluated. A comparison analysis of DVHs from these plans revealed the PTV for AXB estimated a higher maximum dose (5.2%) and lower minimum dose (4.2%) than that of the AAA. The highest dose difference observed 7.06% for the PTV $V_{105%}$. The maximum dose to the lung was also slightly larger in the AXB plans. The percentate volumes of the ipsilateral lung ($V_5$, $V_{10}$, $V_{20}$) receiving 5, 10, and 20 Gy were also larger in AXB plans than for AAA plans. However, these parameters were comparable between both AAA and AXB plans for the contralateral lung. The differences of the maximum dose for the spinal cord and heart were also small. The computation time of AXB plans was 13.7% shorter than that of AAA plans. The average MUs were 3.47% larger for AXB plans than for AAA plans. The results of this study suggest that AXB algorithm can provide advantages such as accurate dose calculations and reduced computation time in lung SABR plan using FFF beams, especially for volumetric modulated arc therapy technique.

• Radiation Oncology Journal
• /
• v.15 no.4
• /
• pp.287-296
• /
• 1997

Purpose : This is study of whether 3-D conformal radiotherapy for carcino-mas of the ethmoid sinus were better than those treated with conventional 2-D plan, Materials and Methods : The 3-D conformal treatment Plans were compared with conventional 2-D plans in 4 patients with malignancy of the ethmoid sinus. Isodose distribution, dose statistics, and dose volume histogram of the planning target volume were used to evaluate differences between 2-D and 3-D plans. In addition. the risk of radiation exposure of surrounding normal critical organs are evaluated by means of point dose calculation and dose volume histogram. Results : 3-D conformal treatment plans for each patient that the better tumor coverages by the planning target volume with improved dose homo-geneity, compared to 2-D conventional treatment Plans in the same Patient. On the other hand, the radiation dose distributions to the surrounding nor-mal tissue organs, such as the orbit and optic nerves are not significantly reduced with our technique, but a substantial sparing in the brain stem and optic chiasm for each patient. Conclusion : Our findings represented the potential advantage of 3-D treatment planning for dose homogeniety as well as sparing of the normal tissue surrounding the tumor. However, further investigational studies are required to define the clinical benefit.

• Radiation Oncology Journal
• /
• v.30 no.3
• /
• pp.146-151
• /
• 2012

Purpose: This treatment planning study was undertaken to evaluate the impact of beam angle configuration of intensity-modulated radiotherapy (IMRT) on the dose of the normal liver in hepatocellular carcinoma (HCC). Materials and Methods: The computed tomography datasets of 25 patients treated with IMRT for HCC were selected. Two IMRT plans using five beams were made in each patient; beams with equidistance of $72^{\circ}$ (Plan I), and beams with a $30^{\circ}$ angle of separation entering the body near the tumor (Plan II). Both plans were generated using the same constraints in each patient. Conformity index (CI), homogeneity index (HI), gamma index, mean dose of the normal liver (Dmean_NL), Dmean_NL difference between the two plans, and percentage normal liver volumes receiving at least 10, 20, and 30 Gy (V10, V20, and V30) were evaluated and compared. Results: Dmean_NL, V10, and V20 were significantly better for Plan II. The Dmean_NL was significantly lower for peripheral (p = 0.001) and central tumors (p = 0.034). Dmean_NL differences between the two plans increased in proportion to gross tumor volume to normal liver volume ratios (p = 0.002). CI, HI, and gamma indices were not significantly different for the two plans. Conclusion: The IMRT plan based on beams with narrow separations reduced the irradiated dose of the normal liver, which would allow radiation dose escalation for HCC.

• Progress in Medical Physics
• /
• v.29 no.4
• /
• pp.106-114
• /
• 2018

This study aimed to compare the performance of previous optimization algorithms against new a photon optimizer (PO) algorithm for intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) plans for prostate cancer. Eighteen patients with prostate cancer were retrospectively selected and planned to receive 78 Gy in 39 fractions of the planning target volume (PTV). All plans for each patient optimized with the dose volume optimizer (DVO) and progressive resolution optimizer (PRO) algorithms for IMRT and VMAT were compared against plans optimized with the PO within Eclipse version 13.7. No interactive action was performed during optimization. Dosimetric and radiobiological indices for the PTV and organs at risk were analyzed. The monitor units (MU) per plan were recorded. Based on the plan quality for the target coverage, prostate IMRT and VMAT plans using the PO showed an improvement over DVO and PRO. In addition, the PO generally showed improvement in the tumor control probability for the PTV and normal tissue control probability for the rectum. From a technical perspective, the PO generated IMRT treatment plans with fewer MUs than DVO, whereas it produced slightly more MUs in the VMAT plan, compared with PRO. The PO showed over potentiality of DVO and PRO whenever available, although it led to more MUs in VMAT than PRO. Therefore, the PO has become the preferred choice for planning prostate IMRT and VMAT at our institution.

• The Journal of the Korean dental association
• /
• v.53 no.11
• /
• pp.770-778
• /
• 2015

This article discusses how to conduct treatment planning and decision making in special needs dentistry. Special needs patients often lack cooperative ability during dental treatment and have a deteriorated oral health status. To overcome the limitation in communication with special needs patients and solve their complicated dental problems, dentists need to have extensive preoperative information about the patients and their caregivers. Treatment procedures should be organized in a patient-centered and cost-effective manner. Additionally, clinical outcomes need to be predicted taking into consideration of the patients' condition. The clinical experience of committed dentists is another factor that enhances the benefits of extensive treatment in special needs patients with many limitations. The insightful treatment decision-making of dentists will contribute to improving the oral health of special needs patients despite the various obstacles.

• Environmental Analysis Health and Toxicology
• /
• v.6 no.1_2
• /
• pp.83-93
• /
• 1991

The specified industrial wastes increased 26% annually during the last 5 years from 1984 to 1988 in Korea, and the special treatment and proper management are required. The effective methods are studied on the process of generation, keeping, transportation, and treatment/disposal for specified industrial wastes and materials. Also, in this paper, the author describes the plans to develop the public disposal facilities and manage specific industrial waste properly in Korea.

• International Journal of Advanced Culture Technology
• /
• v.11 no.3
• /
• pp.9-17
• /
• 2023

Parkinson's disease is a complex neurodegenerative disease characterized by the progressive loss of dopamine-producing neurons in the substantia nigra, resulting in a variety of motor and non-motor symptoms. This study aimed to provide a comprehensive overview of Parkinson's disease, including classification of Parkinson's disease, impairment due to impairment, how disability is assessed, and how it is treated. Major symptoms of Parkinson's disease include tremors, stiffness, bradykinesia, and postural instability, and treatment methods include rehabilitation through drugs, surgical procedures, physical therapy, and occupational therapy. Early diagnosis, individualized treatment interventions, and comprehensive treatment involving a multidisciplinary medical team will be essential to manage Parkinson's disease and improve patients' quality of life. In conclusion, this study will provide comprehensive information on the complex nature of Parkinson's disease and serve as a useful guide for healthcare providers designing treatment plans for Parkinson's patients.

• Journal of Oral Medicine and Pain
• /
• v.33 no.2
• /
• pp.219-228
• /
• 2008

The purpose of this study is to compare the differences between first visits and the recurred time of TMD patients about the number of visits, the treatment plans, the symptoms and the results after the conservative treatments. This could lead us to assess the prognoses of TMDs treated conservatively. We investigated 54 patients who have visited the Department of Oral Medicine in PNUH from 1991 to 2001, diagnosed as TMDs and treated conservatively with medications, physical therapies and splints. The treatments were terminated since the subjects have shown much improvements and resumed when TMDs recurred from 1992 to 2002. We researched the diagnoses, symptoms, the number of visits, the treatment plans and the results comparing the time before and after the treatments were carried out and following are the results. 1. Both the primary and the recurred groups improved after having been treated conservatively. 2. Both the primary and the recurred groups showed no differences in pains and MCOs when they first visited though the noises and LOMs turned out to be more serious in primary group. 3. Both the primary and the recurred groups had no differences in pains, noises, LOMs, MCOs when the treatments were over. 4. The results of treatments were not affected by treatment plans, sex, diagnoses in both primary and recurred groups. 5. Most of the patents tended to visit less than 10 times in recurred patients.

• Progress in Medical Physics
• /
• v.32 no.4
• /
• pp.116-121
• /
• 2021

Purpose: To investigate the effects of dose rate on intensity-modulated radiation therapy (IMRT) quality assurance (QA). Methods: We performed gamma tests using portal dose image prediction and log files of a multileaf collimator. Thirty treatment plans were randomly selected for the IMRT QA plan, and three verification plans for each treatment plan were generated with different dose rates (200, 400, and 600 monitor units [MU]/min). These verification plans were delivered to an electronic portal imager attached to a Varian medical linear accelerator, which recorded and compared with the planned dose. Root-mean-square (RMS) error values of the log files were also compared. Results: With an increase in dose rate, the 2%/2-mm gamma passing rate decreased from 90.9% to 85.5%, indicating that a higher dose rate was associated with lower radiation delivery accuracy. Accordingly, the average RMS error value increased from 0.0170 to 0.0381 cm as dose rate increased. In contrast, the radiation delivery time reduced from 3.83 to 1.49 minutes as the dose rate increased from 200 to 600 MU/min. Conclusions: Our results indicated that radiation delivery accuracy was lower at higher dose rates; however, the accuracy was still clinically acceptable at dose rates of up to 600 MU/min.