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PURPOSE: Intensity modulated radiation therapy (IMRT) is a high precision therapy technique that can achieve a conformal dose distribution on a given target. However, organ motion induced by respiration can result in significant dosimetric error. Therefore, this study explores the dosimetric error that result from various patterns of respiration. MATERIALS AND METHODS: Experiments were designed to deliver a treatment plan made for a real patient to an in-house developed motion phantom. The motion pattern; the amplitude and period as well as inhale-exhale period, could be controlled by in-house developed software. Dose distribution was measured using EDR2 film and analysis was performed by RIT113 software. Three respiratory patterns were generated for the purpose of this study; first the 'even inhale-exhale pattern', second the slightly long exhale pattern (0.35 seconds longer than inhale period) named 'general signal pattern', and third a 'long exhale pattern' (0.7 seconds longer than inhale period). One dimensional dose profile comparisons and gamma index analysis on 2 dimensions were performed RESULTS: In one-dimensional dose profile comparisons, 5% in the target and 30% dose difference at the boundary were observed in the long exhale pattern. The center of high dose region in the profile was shifted 1 mm to inhale (caudal) direction for the 'even inhale-exhale pattern', 2 mm and 5 mm shifts to exhale (cranial) direction were observed for 'slightly long exhale pattern' and 'long exhale pattern', respectively. The areas of gamma index >1 were 11.88%, 15.11%, and 24.33% for 'even inhale-exhale pattern', 'general pattern', and 'long exhale pattern', respectively. The long exhale pattern showed largest errors. CONCLUSION: To reduce the dosimetric error due to respiratory motions, controlling patient's breathing to be closer to even inhaleexhale period is helpful with minimizing the motion amplitude.
Humans ; Respiration

5.Anesthesia machine breathing tube holder.

A Ram DOO ; Sang Kyi LEE

Korean Journal of Anesthesiology 2015;68(1):87-88

6.Pathophysiologic Effects of Mechanical Ventilation.

Cheung Soo SHIN

Korean Journal of Anesthesiology 2006;50(1):1-14

7.Mercury Concentration in Air and in Urine of Workers in A Fluorescent Lamp Manufacturing Factory.

Seung Hoi PARK ; Kwang Jong KIM ; Soung Hoon CHANG ; Chul Whan CHA

Korean Journal of Occupational and Environmental Medicine 1989;1(2):197-205

In order In interpret the relationship among many variables, urinary mercury and at the same time mercury concentration in air were measured for 254 workers of a fluorescent lamp manufacturing factory. And monthly mercury consumption amounts, numbers of monthly producing fluorescent lamps, numbers of inferior lamps and numbers of breakage lamps, numbers of vacuum exhaustion pumps and frequencies of mercury infusion were also investigated from January 1988 to March in 1989. The results were as follows; 1. On the mercury concentration in air by producing line and by working site, all of them were exceed the threshold limit value (0.05mg/m(2)). 2. The highest mercury concentration in air by sampling point was found at the floor of workplace (0.334mg/m(2)) and next were at vacuum exhaustion pimp (0.183mg/m(2)), and breathing zone of workers (0.103mg/m(2)) in order. 3. The highest mean of the mercury concentration in urine by producing line was the automatic exhausting line (80.8microgram/1) and next were high speed exhausting line (72.4microgram/1), and Manual exhausting line (35.8microgram/1) in order. Distribution of workers of the mercury concentration in urine more than 200microgram/1 by working site was the highest (10%) in the vacuum exhaustion pump part and next were sealing part (6.6%), packing part (4.6%), and stem part (4.1%) in order. 4. The correlation coefficient between mercury concentration in urine and in air was the highest (0.302) and next were numbers of breakage lamps (0.223), frequencies of mercury infusion (0.223), numbers of inferior lamps (0.205) in order.
Respiration ; Vacuum