PACS 도입에 의한 현상시스템 폐수 감소효과에 관한 연구

고신관(Shin-Kwan Ko),양한준(Han-Jun Yang),한동균(Dong-Kyoon Han),김욱동(Wook-Dong Kim),강병삼(Bung-Sam Kang) 대한방사선과학회(구 대한방사선기술학회) 2007 방사선기술과학 Vol.30 No.2

  2001년부터 본격적으로 보급되기 시작한 PACS 도입은 영상의학과에서는 필름비용 절감, 인건비 절감, 현상액 사용량 절감, 관리업무 축소, 재 촬영 건수의 감소 등의 효과를 볼 수 있었고, 임상 의사들에게는 의료영상동시 활용, 임상정보의 증대, 진료 환자수의 증가, 의료영상 및 판독결과 활용성 증대 효과를 기대할 수 있는 것으로 알려져 있다.<BR>  환자들에게는 방사선 피폭선량 감소, 진료비 절감, 임상정보를 신속하게 알 수 있는 효과가 있다. 이에 본 저자들은 Full PACS를 도입한 서울 및 경기도의 10개 종합병원을 대상으로 하여 PACS로 인한 긍정적인 여러가지 효과 중 현상, 정착 폐수의 감소 추이를 알아보기 위하여 도입 1년 전과 도입 3년 후를 비교 분석하여 다음과 같은 결론을 얻었다.<BR>  1. 1개월 당 검사 건수는 7357.7건이 증가하였으나 필름 사용량은 90%가 감소하였다.<BR>  2. 현상액 월 평균 소모량은 3년 후 92%가 감소하였고, 정착액은 86%가 감소하였다.<BR>  3. 필름 1장 당월 평균 현상액 소모량은 3년 후 149%가 증가하였고, 정착액은 300%가 증가하였다.<BR>  4. 현상 폐수 발생량은 3년 후 월 평균 88%가 감소하였고, 정착 폐수는 87%가 감소하였다.<BR>  5. 3년 후 필름 1장 당월 평균 현상폐수 발생량은 377%, 정착폐수 발생량은 385%가 증가하였다.   There are some positive effects by the introduction of PACS(Picture Archiving Communication System). This study is to analyze the mutual relation between before and after of the introduction of PACS in terms of the environment effect. It is supposed to cause the reduction of developing and fixing wastewater according to the increase in the rate of a non-film. This study will also show the amount of wastewater.<BR>  Target places were the department of image medicine(diagnostic radiation) of the general hospitals in Seoul and Gyeonggi-Do, which are equiped with full PACS. The authors examined questionnaires on the number of projection, the number of indirect projection, the amount of the film used, the number of radiation image CD loan, the amount of the developing and fixing solution used, the change of the amount of fixing wastewater.<BR>  According to the analysis, we analyzed the change of the amount of developing and fixing solution per a film and the change of the amount of developing and fixing wastewater which is supposed to be reduced proportionally by the introduction of PACS.<BR>  We got conclusion as below after analyzing 8 hospitals except the largest and the least amount of examination, film used, developing and fixing solution and the amount of developing and fixing wastewater in order to decrease the deviation from 10 general hospitals located in Seoul and Gyeonggi- Do. We compared data one year before adopting PACS Versus 3 years after adopting PACS.<BR>  1. The frequences of examination increased to 7,357.7 cases per month but the amount of film used decreased to 90%, from 42,774.4 to 4,181.88 after adopting the PACS.<BR>  2. 3 years after adopting PACS, monthly average amount of developing solution used decreased to 92% and the monthly average amount of fixing solution decreased to 86%.<BR>  3. Monthly average amount of developing solution used per film increased to 1.49 times and fixing solution increased as much as three times.<BR>  4. Monthly average wastewater for developing decreased to 88% and wastewater for fixing decreased up to 87%.<BR>  5. Monthly average wastewater for developing per film increased to 3.77 times and wastewater for fixing increased to 3.85 times.<BR>  Although the amount of film used and the amount of developing and fixing wastewater affected by the reduction of the developing and fixing solution became less on the whole by introduction of PACS, they did not decrease proportionally.<BR>  Moreover the amount of the developing and fixing solution used and the amount of developing and fixing wastewater per a film increased. That means the expectation for an environmental improvement differs from the actual condition.

중재적 방사선 분야 방호용구 차폐효과

고신관(Shin-Kwan Ko),강병삼(Byung-Sam Kang),임청환(Chung-Hwang Lim) 대한방사선과학회(구 대한방사선기술학회) 2007 방사선기술과학 Vol.30 No.3

  중재적 시술의 시술자를 대상으로 방사선 방호용구의 안과 밖의 실제 방사선량을 측정하여 이를 바탕으로 방사선 방호용구의 방사선 차폐율을 비교 분석하는 것이다.<BR>  2005년 5월부터 9월까지 중재적 시술 중에서 시행 빈도가 높은 TACE, PTBD를 시행하는 중재적 시술자 4인에게 방사선 방호용구의 착용 시 피폭선량 감쇄효과를 측정하기 위해 각 신체부위별 방호용구 안과 밖에 TLD를 부착하여 피폭선량을 측정하였다. TLD 부착부위는 Goggle inside, Goggle outside, Thyroid protector inside, Thyroid protector outside, Apron inside(waist level), Apron outside(upper chest level), Hand 4th finger(ring type TLD)와 환경방사선을 측정하기 위해 TLD 10개를 Control room 여러 곳에 위치시켰다.<BR>  TACE 검사시 0.07mmPb Goggle의 사용으로 연속투시방식에서는 평균 53.8%의 선량율감쇄를 보였으며 펄스투시방식에서는 77.6%의 감쇄효과를 보였고, 0.5mmPb Thyroid protector의 사용에서는 연속투시방식에서는 평균 88.9%의 선량율감쇄를 보였으며 펄스투시방식에서는 92.8%로 선량율감쇄에서는 유의한 차이가 없었다.<BR>  PTBD 검사시 0.07mmPb Goggle의 사용으로 평균 62.7%의 선량율감쇄를 보였으며, 0.5mmPb Thyroid protector의 사용에서는 평균 89.1% 선량율이 감쇄 되었고 0.5mmPb Apron의 사용에서도 평균 87.9%의 감쇄효과가 있었다. PTBD 시술은 TACE 시술에 비해 평균 투시시간은 6.14min이나 적었으나 피폭선량은 체부에서 약 3배, 손에서는 40배 이상 피폭되었다.<BR>  납당량이 두꺼운 방호용구를 착용하거나 최소한 권고되어지는 0.5mmPb 이상의 것을 착용하여야 하며, 시술시 눈을 보호하는 Goggle의 착용을 생활화해야 한다. 테이블 아래쪽에 납커튼을 장착하면 복부의 피폭선량율은 평균 38.4% 감쇄하므로 납커튼을 장착하여 산란선을 차폐하여야 한다. 펄스투시방식을 이용하면 연속투시에 비해 피폭선량율이 평균 59.0% 감쇄되므로 연속투시보다 펄스투시방식을 선택하여 피폭선량을 감소시켜야 한다.   The purpose of this study is to evaluate shielding effect of radiation protector for interventional radiologists in procedures by measuring inside and outside of radiation protector.<BR>  In this study, we measured the radiation dose of 4 interventional radiologists during TACE and PTBD procedure for 4 month(2005.05-2005.09).<BR>  Absorbed dose were measured by TLD placed underneath and over radiation protector such as Goggle, Thyroid protector, Apron and placed on the 4th finger of Hand. In addition, we measured background radiation dose in the control room using TLD.<BR>  During TACE procedure, using 0.07mmPb Goggle decreased average 53.8% of radiation dose rate in continuous fluoroscopic mode and decreased average 77.6% of radiation dose rate in pulse fluoroscopic mode. Using 0.5mmPb Thyroid protector decreased average 88.9% of radiation dose rate in continuous fluoroscopic mode and decreased average 92.8% in pulse fluoroscopic mode.<BR>  During PTBD procedure, using 0.07mmPb Goggle decreased radiation dose rate average 62.7%, 87.9% by 0.5mmPb Thyroid protector, 90.5% by 0.5mmPb Apron.<BR>  The average fluoroscopic time of PTBD was 6.14min. shorter than TACE procedure, but radiation exposure dose rate of PTBD was 3 times higher in total body dose, and 40 times higher in hand dose rate than TACE.<BR>  Interventional radiologists must wear thicker protector recommended over 0.5mmPb. Also, they must use lead Goggle during interventional procedure.<BR>  Abdomen dose decreased average 38.4% by drawing a lead curtain under the patient"s table, therefore, they must draw a lead curtain to shield scattering ray.<BR>  Radiation exposure dose decreased average 59.0% by using pulse fluoroscopic mode. So radiologists would better use pulse fluoroscopic mode than continuous fluoroscopic mode to decrease exposure dose.

고정형 쐐기(Physical wedge)와 동적 쐐기(Dynamic wedge)의 조사야 주변 선량에 관한 연구

고신관(Shin-Gwan Ko),민제순(Je-Soon Min),나경수(Kyung-Soo Na),이제희(Je-Hee Lee),박흥득(Heung-Deuk Park),한동균(Dong-Kyoon Han) 대한방사선과학회(구 대한방사선기술학회) 2008 방사선기술과학 Vol.31 No.4

Measurements of the peripheral dose were performed using a 2D array ion chamber and solid water phantom for a 10×10 cm, source-surface distance (SSD) 90 cm, 6 and 15 MV photon beam at depths of 0.5 cm, 5 cm through dmax. Measurements of peripheral dose at 0.5 cm and 5 cm depths were performed from 1 cm to 5 cm outside of fields for the dynamic wedge and physical wedge 15°, 45°. For 6 MV photon beam, the average peripheral dose of dynamic wedge were lower by 1.4% and 0.1% than that of physical wedge For 15 MV photon beam, the peripheral dose of dynamic wedge were lower by maximum 1.6% that of physical wedge. The results showed that dynamic wedge can reduce scattered dose of clinical organ close to the field edge. The wedge systems produce different peripheral dose that should be considered in properly choosing a wedge system for clinical use. 2D-ARRAY chamber를 이용하여 고정형쐐기(Physical wedge filter)와 동적쐐기(Dynamic wedge)의 조사 야 주변의 선량을 비교 ․ 평가하고자 하였다. 고체팬텀 위에 2D-ARRAY seven 29 (PTW, Germany) chamber 를 이용하여 조사야 10 cm×10 cm, SSD 90 cm로 고정시키고, 에너지는 6 MV와 15 MV로 변화시켜 산란선의 영향을 많이 받는 피부 깊이인 5 mm 깊이의 조사야 밖 인접 선량을 측정하였다. 고정형 쐐기 15°, 45°와 선형가속기에 장착된 동적쐐기의 15°, 45°를 측정하여 조사야 끝에서 쐐기의 heel부분과 toe 부분의 1 cm되 는 지점에서 5 cm 지점까지의 1 cm 간격으로 주변선량을 비교, 분석하였다. 6 MV 에너지는 동적쐐기가 고정 형쐐기 보다 조사야 주변 선량이 0.1∼1.4% 정도 모두 낮았다. 15 MV 에너지는 조사야에서 근접한 거리에서 동적쐐기의 선량이 0.4∼0.9% 정도 높지만 멀어지면서 급격하게 감소하여 동적쐐기가 최대 1.6% 낮게 측정 되었다. 동적쐐기는 heel부분과 toe부분의 선량차이가 없는 반면 고정형쐐기는 에너지가 높고 쐐기 각도가 클수록 heel부분 보다 toe부분의 선량이 2% 정도 높게 측정되었다. 따라서 동적쐐기를 사용할 경우 치료주 위선량을 균일하게 감소시킬 수 있으므로 치료부위와 근접한 표면에 가까운 주요장기의 선량을 최소화 할 수 있었다.

X-선 장치의 기술적 인자의 변화에 따른 선량 비교 평가

한동균,고신관,선종률,윤석환,정재은,Han, Dong-Kyoon,Ko, Shin-Gwan,Seon, Jong-Ryul,Yoon, Seok-Hwan,Jung, Jae-Eun 대한디지털의료영상학회 2009 대한디지털의료영상학회논문지 Vol.11 No.2

With the recent development of diagnosis using radiation and increasing demand of the medical treatment, we need to minimize radiation exposure dose. So, This is the method which reduce patient dose by measuring surface dose of radiographic change factor and by comparing theoretical and actual dose, when we take an X-ray which is generally used. By changing the factor of kV, mAs, FSD, whose range is 60 to 120 kV, 20 to 100 mAs, 80 to 180 cm, we compared theoretical surface dose with actual surface dose calculated by the simple calculation program, Bit system, and NDD-M method As a result, when kV and mAs were higher, theoretical surface dose and actual surface dose were more increased. but the higher FSD was, the more decreased surface dose was. According to this, the error were measured about 0.1 to 0.2 mGy in low dose part and about 0.7 to 1.5 mGy in high dose part. Therefore, this shows that theoretical surface dose calculation method is more correct in low dose part than in high dose part. In conclusion, we will have to make constant efforts which can reduce patient and radiographer's exposure dose, studying methods which can predict patient's radiation exposure dose more exactly.

두부(頭部) 단순촬영시(單純撮影時) 적정(適正)한 관전압(管電壓)에 관(關)한 검토(檢討)

안봉선,고신관,박영선,Ahn, Bong-Seon,Ko, Shin-Gwan,Park, Young-Sun 대한방사선과학회 1980 방사선기술과학 Vol.3 No.1

It is the experimental report by using 17cm, 19cm in thickness water-phantom to investigate optimum tube voltage in taking skull roentgenography. The obtained results are as follows: 1. An adequate kVp for P-A projection is range from 80-90. 2. An adequate kVp for lateral projection is range from 75-85.

재구성 알고리즘 변화에 따른 CT 영상의 화질 평가

한동균,박건진,고신관,Han, Dong-Kyoon,Park, Kun-Jin,Ko, Shin-Kwan 대한디지털의료영상학회 2010 대한디지털의료영상학회논문지 Vol.12 No.2

In this study, the correlation among the changes of Modulation Transfer Function(MTF) in the noise and high-contrast resolution and the change of Contrast to noise ratio(CNR) in the low-contrast resolution will be examined to investigate the estimation of image quality according to the type of algorithms. The image data obtained by scanning American Association of Physicists in Medicine(AAPM) phantom was applied to each algorithm and the exposure condition of 120 kVp, 250 mAs, and then the CT number and noise were measured. The MTF curved line of the high-contrast resolution was calculated with Point Spread Function(PSF) by using the analysis program by Philips, resulting in 0.5 MTF, 0.1 MTF and 0.02 MTF respectively. The low-contrast resolution was calculated with CNR and the uniformity was measured to each algorithm. Since the measurement value for the uniformity of the equipment was below ${\pm}$ 5 HU, which is the criterion figure, it was found to belong to the normal range. As the algorithm got closer from soft to edge, the standard deviation of CT number increased, which indicates that the noise increased as well. As for MTF, 0.5 MTF, 0.1 MTF and 0.02 MTF were all sharp algorithms, and as the algorithm got closer from soft to edge, it was possible to distinguish more clearly with the naked eye. On the other hand, CNR gradually decreased, because the difference between the contrast hole CT number and the acrylic CT number was the same while the noise of hole increased.

MDCT에서 화질과 방사선량에 관한 연구

한동균(Dong-Kyoon Han),고신관(Shin-Gwan Ko),양한준(Han-Joon Yang),김문찬(Moon-Chan Kim) 대한방사선과학회(구 대한방사선기술학회) 2007 방사선기술과학 Vol.30 No.2

  본 연구는 MDCT장치에 있어 화질평가와 선량평가 방법을 통하여 장치의 항상성을 유지하며 양질의 의료영상을 제공하는 기초자료로 사용함과 더불어, MDCT의 각 장비에 따른 선량을 평가하고 제시하고자 서울소재 14대의 MDCT장치를 대상으로 시행하여 그 기준을 정량화 하였다.<BR>  MDCT를 이용한 화질측정 즉, CT number와 노이즈, 균일도, 공간분해능, 대조도 분해능과 선량 측정 즉, CTDI와 CTDI<SUB>W</SUB>, CTDI<SUB>W</SUB>/100㎃s의 결과는 다음과 같았다.<BR>  CT number는 평균 0.56±0.70HU, 노이즈는 평균 0.39±0.09HU, 균일도는 평균 1.08±0.52HU이었다. 그리고 공간분해능은 평균 0.48±0.05㎜, 대조도 분해능은 평균 3.65±1.16㎜이었다. CTDI는 head phantom을 이용한 경우 중앙부는 평균 43.2±15.4m㏉, 주변부는 45.6±17.5m㏉이었다, 그리고 body phantom에 있어 중앙부 평균은 13.5±4.5m㏉, 주변부는 29.2±10.2m㏉이었다. 주변부가 중앙부에 비해 2.16배 증가되어 나타났다. head phantom을 이용한 경우 CTDI<SUB>W</SUB><SUB></SUB>는 평균 44.8±16.8m㏉, CTDI<SUB>W</SUB>/100㎃s는 평균 18.8±5.3m㏉, body phantom을 이용한 경우 CTDI<SUB>W</SUB>는 평균 24.0±8.3m㏉이고, CTDI<SUB>W</SUB>/100㎃s는 평균 10.1±2.5m㏉이었다.<BR>  위에서 알 수 있듯 MDCT의 CT number와 노이즈, 균일도, 공간분해능, 대조도 분해능과 CTDI와 CTDI<SUB>W</SUB>, CTDI<SUB>W</SUB>/100㎃s는 전체 장치에서 모두 우수하게 나타났다.   The Purpose of this study is to suggest the basic data for making good quality image and maintaining equipment homeostasis by accepting image quality evaluation and radiation dose evaluation in Multi- detector CT. In this study we surveyed 14 CT equipments in Seoul. The results obtained were as follows; CT number was 0.56±0.70HU. Noise was 0.39±0.09HU.<BR>  Uniformity was 1.08±0.52HU. High contrast resolution was 0.48±0.05㎜ and low contrast resolution was 3.65±1.16㎜. For CTDI, the central part and the peripheral part of head phantom were 43.2±15.4m㏉ and 45.6±17.5m㏉, respectively. For body phantom, the central part and the peripheral part of head phantom were 13.5±4.5 and 29.2±10.2m㏉, respectively.<BR>  CTDI<SUB>W</SUB> was 44.8±16.8m㏉ and CTDI<SUB>W</SUB>/100㎃s was 18.8±5.3m㏉ using head phantom. CTDI<SUB>W</SUB> was 24.0±8.3m㏉ and CTDI<SUB>W</SUB>/100㎃s was 10.1±2.5m㏉ using body phantom.<BR>  The refore, CT number, noise, high contrast resolution, low contrast resolution, CTDI, CTDI<SUB>W</SUB> and CTDI<SUB>W</SUB>/100㎃s of MDCT were showed excellently in all equipments.

유방촬영용 X선관 target/filter 조합에 따른 MTF영상평가에 관한 고찰

양한준(Han-Jun Yang),고신관(Sin-Kwan Ko),주미화(Mi-Hwa Joo) 대한방사선과학회(구 대한방사선기술학회) 2007 방사선기술과학 Vol.30 No.2

  인체의 유방은 조직 간의 엑스선 흡수차가 작기 때문에 엑스선관 Target/Filter의 적절한 조합으로 피사체의대 조도를 높이는 일이 중요하다. 최근 장비들은 다양한 유방두께와 유선조직 밀도에 따라서 Target/Filter의 조합을 변화시켜 환자의 피폭 선량 경감 및 진단에 알맞는 화질을 얻고 있다. 본 실험은 Target/Filter의 조합에 따라 해상력 챠트를 이용하여 MTF 영상의 평가와 유방 팬톰 영상을 평가하여 다음과 같은 결론을 얻었다.<BR>  1. 아크릴 두께(2㎝, 3㎝, 4㎝)의 조합(Mo/Mo, Mo/Rh. Mo/Al, Rh/Rh, Rh/Al)에 따라 고유원자번호에 의해 엑스선 에너지에서 큰 차이를 보였다.<BR>  2. MTF 곡선에서 선예도를 나타내는 MTF 0.5에서의 Lp/㎜ 값은 아크릴 2㎝일 때 Mo/Mo은 2.4Lp/㎜, 4㎝일 때 Mo/Rh은 2.63Lp/㎜, 6㎝일 때 Rh/Rh은 2.9Lp/㎜로 높게 나타났다.<BR>  3. 분해능을 나타내는 MTF 값은 아크릴 2㎝일 때 Mo/Mo은 6.0Lp/㎜, 4㎝일 때 Rh/Al은 4.60Lp/㎜, 6㎝일 때 Rh/Al은 6.03Lp/㎜로 MTF 값이 높게 나타났다.<BR>  4. 시각적 식별이 가능한 2.5Lp/㎜에서 MTF 값은 2㎝일 때 Mo/Mo은 0.48Lp/㎜, 4㎝일 때 Mo/Rh은 0.53Lp/㎜, 6㎝일 때 Rh/Rh은 0.59Lp/㎜로 높게 나타났다.<BR>  5. 유방 팬톰 영상평가에서는 Mo/Mo일 때 12점, Mo/Rh일 때 11점, Rh/Rh일 때 10.5점, Mo/Al일 때 10점, Rh/Al일 때 9점 순으로 나타났다.   It is important to consider the contrast of object in Mammography because an absorption gap between tissues of body and breast in breast is low. This study is to evaluate MTF image with resolution chart according to change of combination of target and filter. The results were as follows :<BR>  1. There were significant differences in X-ray energy according to combination of filter(Mo/Mo, Mo/Rh. Mo/Al, Rh/Rh, Rh/Al) and acrylic thickness(2㎝, 3㎝, 4㎝).<BR>  2. The value of lp/㎜ on MTF to 0.5 showed that the sharpness in MTF curve was 2.4 compared to Mo/Mo and 2㎝ acryl, 2.63 in Mo/Rh and 4cm acryl, and 2.9 in Rh/Rh and 6㎝ acryl.<BR>  3. The value of lp/㎜ on MTF showed that the resolution in MTF curve was 6.0 compared to Mo/Mo and 2㎝ acryl, 4.60 in Rh/Al and 4㎝ acryl, and 6.03 in Rh/Al and 6㎝ acryl.<BR>  4. The value of MTF on 2.5lp/㎜ distinguishable visually was 0.48 compared to Mo/Mo and 2㎝ acryl, 0.53 in Mo/Rh and 4㎝ acryl, and 0.59 in Rh/Rh and 6㎝ acryl.<BR>  5. For the evaluation of an image of the mammo-phantom, the score of Mo/Mo was 12 points, Mo/Rh 11, Rh/Rh 10.5, Mo/Al 10, Rh/Al 9.0, respectively.

CT장치의 성능평가에 관한 연구

한동균,김문찬,양한준,고신관,Han Dong Kyoon,Kim Moon Chan,Yang Han Joon,Ko Shin Kwan 대한방사선사협회 2001 대한방사선사협회지 Vol.27 No.2

In medical equipments as complex as a computed tomographic equipment, routine quality control procedures are essential to the detection of small pathologic change in soft tissue as well as and the maintenance of optimal image quality. This study was condu

공동(air cavity)의 존재 시 실험적 선량분포와 치료계획상의 선량분포 비교

김연래(Yon-Lae Kim),서태석(Tae-Suk Suh),고신관(Shin-Gwan Ko),이정우(Jeong-Woo Lee) 대한방사선과학회(구 대한방사선기술학회) 2010 방사선기술과학 Vol.33 No.3

고 에너지 광자선 치료 시 공동의 존재로 인한 실험적 선량분포와 치료계획상의 선량분포의 변화를 비교, 평가 하고자 하였으며, 선형가속기의 6 MV 광자선을 이용해서 폴리스틸렌 팬텀, 자체 제작한 아크릴 팬텀으로 공동을 만들고 표면에서 공동까지의 거리는 3 cm로 하고 선원-측정기간 거리는 100 cm로 고정하였고 공동의 크기는 가로 × 세로 × 높이로 정하였다. 공동의 넓이, 높이, 존재 유무, 그리고 조사면과 공동의 크기 비율에 따른 깊이에 대한 선량변화를 평판형전리함과 미소전류계를 이용하여 측정하였다. 치료계획상의 선량분포는 불균질 보정을 하고 치료계획을 하여 비교하였다. 그 결과 공동의 넓이가 커짐에 따라 선량은 점차 감소하였다. 공동의 존재 시에, 공동후면 이후 깊이선량은 공동의 비존재시보다 크게 나타났다. 공동의 크기를 5×5×3 cm 3 로 고정했을 때 조사면이 4×4 cm 2 , 5×5cm, 6×6 cm일 경우에 rebuild-up이 일어났다. 그러나 조사면이 10×10 cm에서는 선량감소만이 나타났다. 또한 조사면을 5×5 cm 2로 고정했을 때, 공동의 넓이가 4×4 cm , 5×5 cm 2 일 경우에는 rebuild-up현상 이 일어났지만, 2×2 cm 2 , 3×3 cm 2 일 경우에는 일어나지 않았다. 모든 경우에서 치료계획상의 선량분포에서 rebuild-up 현상이 나타나지 않았다. 따라서 공동이 위치한 곳에 종양이 존재할 때는 치료계획상의 선량분포에 차이가 있으므로 주의를 할 필요가 있다. This study is compared that the dose distribution by experimentation and radiation therapy planning (RTP) when the air cavity region was treated high energy photon.The dose measurements were performed with a 6 MV photon beam of linear accelerator. The poly-styrene and self made acyl phantom were similar to tissue density of the human body. A parallel plate chamber was connected to an electrometer. The measurement setup was SCD (Source Chamber Distance) 100 cm and the distance of surface from air cavity was 3 cm. Absorbed dose of interface were measured by area and height. The percent depth dose were measured presence and absence of air cavity, depth ac-cording to a ratio of field size and air cavity size. The dose distribution on planning was expressed to do the inhomogeneity correction. As the area of air cavity was increased, the absorbed dose were gradually reduced. It was slightly in-creased, when the height of air cavity was changed from 0 cm to 0.5 cm. After the point, dose was decreased. In case of presence of air cavity, dose after distal air cavity interface was more great than ab-sence of air cavity. The rebuild up by field size and area of air cavity occurred for field size, 4×4 cm 2 , 5×5 cm and 6×6 cm, with fixed on area of air cavity, 5×5 cm. But it didn't occur at 10×10 cmfield size. On the contrary, the field size was fixed on 5×5 cm 2 , rebuild up occurred in area of air cavity, 4×4 cm 2 , 5×5 cm 2 . but, it did not occur for air cavity, 2×2 cm 2 , 3×3 cm 2 . All of the radiation therapy planning were not occurred rebuild up. It was required to pay attention to treat tumor in air cavity because the dose distribution of planning was different from the dose distribution of patient.