Characteristics of 15 MV Photon Beam from a Varian Clinac 1800 Dual Energy Linear Accelerator

김계준,이종영,박경란,Kim, Kye-Jun,Lee, Jong-Young,Park, Kyung-Ran The Korean Society for Radiation Oncology 1991 Radiation Oncology Journal Vol.9 No.2

국내에서 처음으로 사용되는 CLINAC 1800에서 발생된 15MV X-선의 특성을 구하기 위하여 3 Dimensional water Phantom Dosimetry system)를 이용하여 방사선 치료에 근간이 되는 심부선량 백분율(POD), 최대 조직 비율(TMR), 편평도(beam profile), 대칭도, Wedge인자 등을 측정하였고 선량계산을 위하여 출력 인자들을 구하였다. 1. 선축상 최대치 지점(Dmax)은 SSD 100cm일때 조사면이 $10\times10cm^2$에서 $3.0\pm0.1$ cm이였고 $4\times4cm^2,\;35\times35cm^2$에서 각각 $3.1\pm0.1\;cm,2.2\pm0.1$ cm으로 조사면이 넓어지면서 측정치가 표면에 가까워지는 결과를 보였다. 2. 조직표면 선량(Surface Dose)는 SSD 100cm일때 조사면이 $10\times10cm^2$에서 $15.5\%$이였고 $4\times4cm^2,\;35\times35cm^2$에서 각각 $9.8\%\;,51.2\%$로 조사면이 넓어지면서 표면 선량은 증가하는 결과를 보였다. 3. 심부선량 백분율(PDO)은 SSD 100cm에서 측정하였고 조사면이 $10\times10cm^2$이고 10cm depth에서 $76.8\%$이였고 $80\%,\;50\%$ 선량의 깊이는 각각 $9.1\pm0.1\;cm,19.9\pm0.2\;cm$으로 측정되었다. 4. 최대조직비율(TMR)은 심부선량 백분율(PDD)로부터 계산하였고 측정값과의 차이는 $10\times10cm^2$ 조사면에서 평균 $1\;%$ 이내의 오차를 보였다. 5. 대칭도(symmetry)와 편평도(flatness)는 조사면 $10\times10cm^2$일때 각각 $0.73\%,\;2.72\%$이였다. 6. 출력인자(output factor)는 $10\times10cm^2$ 기준 조사면에서 흡수선량을 1로 하였을때 $4\times4cm^2,\;35\times35cm^2$ 조사면에서는 각각 0.927, 1.087로 측정되었는데 조사면이 증가할수록 흡수량이 증가하는 결과를 보였다. 7. Wedge factor는 $15^{\circ}\;30^{\circ}\;45^{\circ}\;60^{\circ}$를 10cm깊이에서 측정하였는데 0.825, 0.099, 0.560, 0.457로 각각 측정되었고 아크릴 0.4 mm Tray의 투과율은 0.976이였다. 8. 15 MV X-선에 의한 납벽층의 반가층 두께는 13 mm였고 Cerrobend의 반가층은 15.5 mm으로 측정되었다. A comprehensive set of dosimetric measurements has been made on the Varian Clinac 1800 15 MV photon beam. Beam quality, percentage depth dose, dose in the build up region, output, symmetry and flatness, transmission through iead (Cerrobend), tray attenuation, isodose curves for the open and wedged fields were measured using 3 dimensional water phantom dosimetry system (including film densitometer system) and polystyrene phantoms. These dosimetric measurements sufficiently characterized the beam to permit clinical use. The depth dose characteristics of photon beam is $d_{max}$ of 3.0 cm and percentage depth dose of $76.8\%$ at 10 cm,100 cm source-surface distance, field size of $10\times10\;cm^2$ for 15 MV X-ray beam. The Output factors ranged 0.927 for $4\times4\;cm^2$ field to 1,087 for $35\times35\;cm^2$ field. The build-up level of maximum dose was at 3.0 cm and surface dose was approximately $15.5\%$ for a field size $10\times10\;cm^2$ The stability of output is $within\pm1\%$ and flatness and symmetry are $within\pm3\%$. The half value thickness (HVL) of lead is 13 mm, which corresponds to an attenuation coefficient of $0.053\;mm^{-1}$. These figures compare facorably with the manufacturesr`s specifications.

The dosimetric Properties of Electron Beam Using Lyon Intraoperative Device for Intraoperative Radiation Therapy

김계준(Kye Jun Kim),박경란(Kyung Ran Park),이종영(Jong Young Lee),김희연(Hie Yeon Kim),성기준(Ki Joon Sung),추성실(Sung Sil Chu) 대한방사선종양학회 1992 Radiation Oncology Journal Vol.10 No.1

수술중 방사선치료를 환자에 적용하기에 앞서 본원이 보유하고 있는 LID를 이용한 전자선의선량분포 특성을 연구하였다. 이러한 선량 특성에 대한 자료는 적절한 Cone의 모향이나 크기, 에너지를 결정하게하며 빠르고 정확한 계산을 위하여 필요하다. 따라서, 본 저자들은 3-Dimensional Water Phantom Dosimetry System를 이용하여 Cone의 크기, Cone의 모양, 보상필터 사용 유무에 따라 Cone의 출력인자, 조직표면선량, 선축상 최대치 지점, 90%의 깊이, 대칭도와 편평도, SSD 보상인자, 선량분포 등을 측정하여 다음과 같은 결과를 얻었다. 1) Cone의 출력인자는 Cone 모양에 따라 각각 측정하였으며 Cone의 크기와 에너지가 작을수록 급격하게 감소하는 결과를 보였다. 2) 보상 필터의 하나인 Flattening Filter를 사용한 결과 표면 선량이 6MeV, 9MeV, 12MeV에 대하여 각각 85.3%, 89.2%, 93.4%였고, 이 보상 필터를 사용하므로 선량률과 beam의 투과율은 감소하지만 치료부위에 따라 beam의 모양을 변형시키며 특히, 표면선량을 90%나 그 이상으로 증가시킬수 있었다. 3) 3차에 걸친 beam의 collimation과 보상 필터를 결합하여 사용한 결과 매우 좋은 beam의 균일성과 편평도 뿐만아니라 90% 등선량곡선 넓이가 커지는 결과를 보였다. 4) 치료를 위하여 중요한 간격인 SSD 100cm에서 SSD 110cm까지의 출력인자는 측정치와 계산치가 Cone의 크기와 모양, 에너지에 따라 1~3%의 차이를 보였다. We have studied the dosimetric properties of electron beam using Lyon intraoperative device for intraoperative radiation therapy. The dosimetry data had compiled in such a way that a quick and correct decision regarding the cone shape, energy, and accurate calculations could be made. Using 3 dimensional water phantom, we have got the following data: cone output ratios. surface dose. dmax, d90 flatness, symmetry, beam profiles, isodose curve. and SSD correction factors, The cone output ratios were measured with straight and bevelled cone. respectively. As the cone size and the energy were reduced, the cone output ratios decreased rapidly. With the flattening filter. the surface dose increased by electron beam to 85.3%, 89.2%, and 93.4%. for 6 MeV. 9 MeV, and 12 MeV. respectively. It is important to increase the surface dose to 90% or more. Inspite of diminishing dose rate and beam penetration. this flattening filter increases the treatment volume significantly. With the combination of the three levels Collimation and the flattening filter. we achieved good homogeneity of the beam and better flatness and the diameter of the 90% isodose curve was increased. It is important to increase the area that is included in the 90% isodose level. The value of measured no calculated SSD correction factors did not agree over the clinically important range from 100 cm to 110 cm.

Characteristics of 15 MV Photon Beam from a Varian Clinac 1800 Dual Energy Linear Accelerator

Kye Jun Kim(김계준),Jong Yong Lee(이종영),kyung Ran Park(박경란) 대한방사선종양학회 1991 Radiation Oncology Journal Vol.9 No.1

국내에서 처음으로 사용되는 CLINAC 1800에서 발생된 15MV X-선의 특성을 구하기 위하여 3 Dimensional water Phantom Dosimetry system를 이용하여 방사선 치료에 근간이 되는 신부선량 백분율(PDD), 최대 조직 비율(TMR), 편평도 (beam profile), 대칭도, Wedge 인자 등을 측정하였고 선량계산을 위하여 출력인자들을 구하였다. 1. 선축상 최대치 지점(Dmax)은 SSD 100cm일때 조사면이 10x10㎠에서 3.0±0.1 cm 이였고 4x4㎠ 35x35㎠에서 각각 3.1±0.1cm, 2.2±0.1cm으로 오사면이 넓어지면서 측정치가 표면에 가까워지는 결과를 보였다. 2. 조직표면 선량(Surface Dose)는 SSD 100cm 일때 조사면이 10x10㎠에서 15.5%이였고 4x4㎠ 35x35㎠에서 각각 9.8%, 51.2%로 조사면이 넓어지면서 표면 선량은 증가하는 결과를 보였다. 3. 심부선량 백분율(PDD)은 SSD 100cm에서 측정하였고 조사면이 10x10㎠이고 10cm depth에서 76.8%이었고 80%, 50% 선량의 깊이는 각각 9.1±0.1cm, 19.9±0.2cm으로 측정되었다. 4. 최대조직비율(TMR)은 심부선량 백분율(PDD)로부터 계산하였고 측정값과의 차이는 10x10㎠ 조사면에서 평균 1% 이내의 오차를 보였다. 5. 대칭도(symmerty)와 편평도(flatness)는 조사면 10x10㎠일때 각각 0.73%, 2.72%이였다. 6. 출력인자(output factor)는 10x10㎠ 기준 조사면에서 흡수선량을 1로 하였을때 4x4㎠, 35x35㎠ 조사면에서는 각각 0.927, 1.087로 측정되었는데 조사면이 증가할수록 흡수량이 증가하는 결과를 보였다. 7. Wedge factor는 15° 30° 45° 60°를 10cm 깊이에서 측정하였는데 0.825, 0.699, 0.560, 0.457로 각각 측정되었고 아크릴 6.4mm Tray의 투과율은 0.976이였다. 8. 15MV X-선에 의한 납벽층의 반가층 두께는 13mm였고 Cerrobend의 반가층은 15.5mm으로 측정되었다. A comprehensive set of dosimetric measurements has been made on the Varian Clinac 1800 15 MV photon beam. Beam quality, percentage depth dose, dose in the build up region, output, symmetry and flatness, transmission through lead (Cerrobend), tray attenuation, isodose curves for the open and wedged fields were measured using 3 dimensional water phantom dosimetry system (including film densitometer system) and polystyrene phantoms. These dosimetric measurements sufficient-ly characterized the beam to permit clinical use. The depth dose characteristics of photon beam is dmax of 3.0 cm and percentage depth dose of 76.8% at 10 cm, 100 cm source-surface distance, field size 10x10 ㎠ for 15 MV X-ray beam. The Output factors ranged 0.927 for 4x4 ㎠ field to 1.087 for 35x35 ㎠ field. The build-up level of maximum dose was at 3.0 cm and surface dose was approximately 15.5% for a field size 10x10 ㎠. The stability of output is within ±1% and flatness and symmety are within ±3%. The half value thickness (HVL) of lead is 13mm, which corresponds to an attenuation coefficient of 0.053mm. These figures compare favorably with the manufacturer's specifications.

쐐기 인자 결정 깊이에 관한 연구

김현자,이병용,김계준,배훈식,최은경,장혜숙,안기정 한국의학물리학회 1992 의학물리 Vol.3 No.2

쐐기 인자의 깊이 의존성 연구를 통하여 적절한 쐐기 인자 결정 깊이에 관한 연구를 하였다. 4 MV, 6MV, 10MV, 15MV (사용가속기 Varian, Siemens, Mitsubishi) 선종에 대하여 명목 쐐기 각도 15$^{\circ}$, 30$^{\circ}$, 45$^{\circ}$, 60$^{\circ}$, 쐐기를 사용하여, 깊이 변화에 따르는 쐐기 인자 변화를 살펴보았다. 적정 쐐기 인자 결정 깊이를 알아보기 위하여 서울중앙병원, 부산침례병원, 원주기독병원에서 1990. 1991. 12 사이에 쐐기를 이용하여 방사선 치료를 받은 환자중 무작위로 614명을 추출하여 사용 에너지별, 쐐기 각도별, 치료 깊이별 분석을 시도하였다. 전체 환자의 60% 이상이 8cm$\pm$2.5cm 깊이에서 치료를 받았다. 쐐기 인자를 선량 최대 깊이로 결정할 경우 모든 환자가 평균 2%(최대 4%)의 치료 오차를 갖게 된다. 그러나 8cm깊이를 쐐기 인자 결정 깊이로 할 경우 평균 0.5% 선량 오차 이내로(사용가속기 기종, 에너지, 쐐기 각도에 관계 없이 최대 오차 1.7% 이내) 정확한 치료를 받을 수 있음을 알았다. 따라서 쐐기 인자는 5-10cm(8cm) 깊이에서 결정되는 것이 합리적인 것을 알았다. Traditionally. the wedge factor of universal wedge is regarded as constant for small depth. Recently. some investigators have reported the beam hardening effect from wedged beam even in small depth. suggesting that the wedge factors are depth dependent values. Here authors performed the study to determine the proper depth of measurement for wedge factor. In this study. we have measured the wedge factors (nominal wedge angles 15, 30, 45, and 60) not only for depth maximum. but also for each depth, for several energies (4MV, 6MV, 10MV, and 15MV) of various machines (Varian, Siemens, Mitsubishi). And we have analysed the treatment depth of 614 patients who had been treated with wedged field at our hospitals to determine of the proper depth of the measurement point for wedge factor. More than 60% of the patients are treated at the depth of 8cm$\pm$2.5cm with the wedged field for various machines. energies, and wedge angles. The results of the wedge factor measurements show that the systemic error of average 2% (maximum 4%) might be inherently originated for the patients who had been treated with wedged field if we adapt the depth maximum as the wedge factor determination depth due to beam hardening effect. But we could achieve average error less than 0.5% (maximum within 1.7%) if we use 8cm for wedge factor measurement point We conclude that the measurement depth point for wedge factor should be 8cm in order to deliver more accurate dose to target for Korean patients. instead of depth maximum.

선형가속기를 이용한 방사선 수술의 선량분포의 실험적 확인

박경란(Kyung Ran Park),김계준(Kye Jun Kim),추성실(Sung Sil Chu),이종영(Jong Young Lee),조철우(Chul Woo Joh),이창걸(Chang Geol Lee),서창옥(Chang Ok Suh),김귀언(Gwi Eon Kim) 대한방사선종양학회 1993 Radiation Oncology Journal Vol.11 No.2

The calculation of dose distribution in multiple arc stereotactic radiotherapy is a three-dimensional problem and, therefore, the three-dimensional dose calculation algorithm is important and the algorithm's accuracy and reliability should be confirmed experimentally. The aim of this study is to verify the dose distribution of stereotactic radiosurgery experimentally and to investigate the effect of the beam quality, the number of arcs of radiation, and the tertiary collimation on the resulting dose distribution. Film dosimetry with phantom measurements was done to get the three-dimensional orthogonal isodose distribution. All experiments were carried out with a 6 MV X-ray, except for the study of the effects of beam energy on dose distribution, which was done for X-ray energies of 6 and 15 MV. The irradiation technique was from 4 to 11 arcs at intervals of from 15 to 45 degrees between each arc with various field sizes with additional circular collimator. The dose distributions of square field with linear accelerator collimator compared with the dose distributions obtained using circular field with tertiary collimator. The parameters used for comparing the results were the shape of the isodose curve, dose fall-offs fom 90% to 50% and from 90%;to;20% isodose line for the steepest and shallowest profile, and A={90% isodose area / (50% isodose area - 90% isodose area)}(modified from Chierego). This ratio may be considered as being proportional to the sparing of normal tissue around the target volume. The effect of beam energy in 6 and 15 MV X-ray indicated that the shapes of isodose curves were the same. The value of ratio A and the steepest and shallowest dose fall-offs for 6 MV X-ray was minimally better than that for 15 MV X-ray. These data illustrated that an increase in the dimensions of the field from 10 to 28 mm in diameter did not significantly change the isodose distribution. There was no significant difference in dose gradient and the shape of isodose curve regardless of the number of arcs for field sizes of 10, 21, and 32 mm in diameter. The shape of isodose curves was more circular in circular field and square in square field. And the dose gradient for the circular field was slightly better than that for the square field.

Thermal Distribution in a Phantom Using 8MHz RF capacitive Type hyperthermia

이종영(Jong Young Lee),박경란(Kyung Ran Park),김계준(Kye Jun Kim),성기준(Ki Joon Sung) 대한방사선종양학회 1991 Radiation Oncology Journal Vol.9 No.2

8MHz 고주파 유전형 가열장치로 모형을 가열할 때에 전극의 크기와 모형의 두께에 따른 온도 분포를 알아보기 위하여 다양한 크기의 전극과 다양한 두께의 모형을 조합하여 실험하였다. 전극은 10, 15, 20, 25, 그리고 30cm 크기를 사용하였고 모형은 10, 15, 20, 25, 그리고 30cm 두께를 사용하였다. 모형의 두께가 25cm이상일 경우에는 전극의 크기가 모형의 두께보다 크거나 혹은 같을때에 중심부에 균일한 온도 분포를 얻을 수 있었으나, 무형의 두께가 20cm이하일 경우에는 전극의 크기가 모형의 두께와 같을 때는 균일한 온도 분포를 얻을 수 없었고 전극의 크기가 모형의 두께보다 클 때만 균일한 온도 분포를 얻을 수 있었다. 크기가 다른 한쌍의 전극을 사용하여 가열시에는 작은 전극 쪽으로 가열 부분이 집중되었고 그 현상은 전극크기의 차가 클 수록 심하였다. To evaluate the temperature distribution according to the size of the electorde and the thickness of the phantom using 8MHz radiofrequency capacitive heating device, various sized electrodoes and phantoms were used in combination. The radii of the electrodes are 10, 15, 20, 25, and 30cm and the thickness of cylindrical phantoms with diameter 30cm were 10, 15, 20, 25, 30, and 35cm. When the thickness of the phantom was 25cm or 30cm, homogenous heating was achieved by using the electrode which diameter was equal to or greater than the thickness of the phantom. When the thickness of the phantom was 20cm or less. homogenous heating was not achieved by using the electrode which diameter was equal to the thickness of the phantom, but achieved by the larger diameter of the electorode. When the sizes of paird electrodes were not equal, the smaller electrode side was preferentially heated.

부정형 조사면에서의 TLD를 이용한 방사선 흡수선량 측정

이종영(Jong Young Lee),박경란(Kyung Ran Park),김계준(Kye Jun Kim) 대한방사선종양학회 1994 Radiation Oncology Journal Vol.12 No.2

In clinical radiotherapy, the use of wide and irregular field techniques frequently results in considerable tumor dose inhomogeneity because of, the variation in physical characteristics of irradiated volumes. This report describes an analysis of the dosimetry of the irregular fields such as radaition fields for Hodgkin's disease(mantle field), esophageal cancer, and lung cancer when a 6MV and a 15MV linear accelerators are utilized. Doses were measured in a Rando phantom using methods of thermoluminescence dosimetry(TLD) and were calculated by radiotherapy planning computer system with the Clarkson's method for calculation of a irregular field. A dose variation of 5-22%, 6-9%, 6-14% were found in the mantle field, esophageal cancer field, lung cancer field respectively. Higher doses occurred in the superior portion of the irregular field. The sites of maximum dose variation were the supraclavicular and the upper spinal cord region. To adjust for these substantial differences, a compensator or a shrinking field technique should be adopted.