전립선암의 위치는 방사선 치료도중 변하는 경우가 많으며 이는 종양선량을 낮추고 정상조직선량이 높아질 수 있다. 이 논문의 목적은 방사선 치료중에 전립선암의 위치 및 깊이 변화를 자동적으로 감지하는 시스템을 개발하고 이를 적용해 환자의 국부에 조사되는 방사선량의 변화를 최소화 하는 데 있다. 이 연구에서는 10명의 환자로부터 38장의 영상자료를 통해 수행되었으며 전립선암에 부착된 금-표지자를 이용해 종양의 질량중심을 구하고 이를 기반으로 종양의 위치변화를 감지하였다. 전립선암의 평균적인 위치변화는 좌우와 위아래로 각각 0.9 mm와 2.3 mm이었으며 최고 위치변화는 각 각 3.3 mm와 7.2 mm였다. 일상적으로 전립선암의 양성자치료에 많이 사용되는 마주보는 두 개의 양성자빔(bilateral beam configuration) 조건에서 좌우의 위치변화는 깊이 변화를 의미하며 이는 약 0.7 mm에서 3.3 mm까지 변화하고 있음을 알 수 있었다. 실험결과 종양의 깊이 변화가 1 mm, 2 mm 그리고 3 mm 보다 많이 차이 나는 경우가 각각 42.1%, 26.3% 그리고 2.6%로 나타났다. 이러한 결과를 토대로 봤을 때 양성자치료에서 자동적으로 종양의 깊이 변화를 분석하는 것이 가능하다는 것을 알 수 있었으며 이를 이용한다면 종양선량을 높이고 정상조직선량을 낮추어 치료효과를 높일 수 있다.
전립선암의 위치는 방사선 치료도중 변하는 경우가 많으며 이는 종양선량을 낮추고 정상조직선량이 높아질 수 있다. 이 논문의 목적은 방사선 치료중에 전립선암의 위치 및 깊이 변화를 자동적으로 감지하는 시스템을 개발하고 이를 적용해 환자의 국부에 조사되는 방사선량의 변화를 최소화 하는 데 있다. 이 연구에서는 10명의 환자로부터 38장의 영상자료를 통해 수행되었으며 전립선암에 부착된 금-표지자를 이용해 종양의 질량중심을 구하고 이를 기반으로 종양의 위치변화를 감지하였다. 전립선암의 평균적인 위치변화는 좌우와 위아래로 각각 0.9 mm와 2.3 mm이었으며 최고 위치변화는 각 각 3.3 mm와 7.2 mm였다. 일상적으로 전립선암의 양성자치료에 많이 사용되는 마주보는 두 개의 양성자빔(bilateral beam configuration) 조건에서 좌우의 위치변화는 깊이 변화를 의미하며 이는 약 0.7 mm에서 3.3 mm까지 변화하고 있음을 알 수 있었다. 실험결과 종양의 깊이 변화가 1 mm, 2 mm 그리고 3 mm 보다 많이 차이 나는 경우가 각각 42.1%, 26.3% 그리고 2.6%로 나타났다. 이러한 결과를 토대로 봤을 때 양성자치료에서 자동적으로 종양의 깊이 변화를 분석하는 것이 가능하다는 것을 알 수 있었으며 이를 이용한다면 종양선량을 높이고 정상조직선량을 낮추어 치료효과를 높일 수 있다.
Depth of prostate volume from the skin can vary due to intra-fractional and inter-fractional movements, which may result in dose reduction to the target volume. Therefore we evaluated the feasibility of automated depth determination-based adaptive proton therapy to minimize the effect of inter-fract...
Depth of prostate volume from the skin can vary due to intra-fractional and inter-fractional movements, which may result in dose reduction to the target volume. Therefore we evaluated the feasibility of automated depth determination-based adaptive proton therapy to minimize the effect of inter-fractional movements of the prostate. Based on the center of mass method, using three fiducial gold markers in the prostate target volume, we determined the differences between the planning and treatment stages in prostate target location. Thirty-eight images from 10 patients were used to assess the automated depth determination method, which was also compared with manually determined depth values. The mean differences in prostate target location for the left to right (LR) and superior to inferior (SI) directions were 0.9 mm and 2.3 mm, respectively, while the maximum discrepancies in location in individual patients were 3.3 mm and 7.2 mm, respectively. In the bilateral beam configuration, the difference in the LR direction represents the target depth changes from 0.7 mm to 3.3 mm in this study. We found that 42.1%, 26.3% and 2.6% of thirty-eight inspections showed greater than 1 mm, 2 mm and 3 mm depth differences, respectively, between the planning and treatment stages. Adaptive planning based on automated depth determination may be a solution for inter-fractional movements of the prostate in proton therapy since small depth changes of the target can significantly reduce target dose during proton treatment of prostate cancer patients.
Depth of prostate volume from the skin can vary due to intra-fractional and inter-fractional movements, which may result in dose reduction to the target volume. Therefore we evaluated the feasibility of automated depth determination-based adaptive proton therapy to minimize the effect of inter-fractional movements of the prostate. Based on the center of mass method, using three fiducial gold markers in the prostate target volume, we determined the differences between the planning and treatment stages in prostate target location. Thirty-eight images from 10 patients were used to assess the automated depth determination method, which was also compared with manually determined depth values. The mean differences in prostate target location for the left to right (LR) and superior to inferior (SI) directions were 0.9 mm and 2.3 mm, respectively, while the maximum discrepancies in location in individual patients were 3.3 mm and 7.2 mm, respectively. In the bilateral beam configuration, the difference in the LR direction represents the target depth changes from 0.7 mm to 3.3 mm in this study. We found that 42.1%, 26.3% and 2.6% of thirty-eight inspections showed greater than 1 mm, 2 mm and 3 mm depth differences, respectively, between the planning and treatment stages. Adaptive planning based on automated depth determination may be a solution for inter-fractional movements of the prostate in proton therapy since small depth changes of the target can significantly reduce target dose during proton treatment of prostate cancer patients.
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가설 설정
13) As one can see from Fig. 5(c), (d), edges from bony structures are the most significant features in images. Therefore, if two images from pelvis are matched based on edge correlation, it is most likely to be matched based on the bony structures of two images.
제안 방법
All patients were scanned in the supine position and two images, a reference image and a test image, were obtained from a digitally reconstructed radiograph (DRR) through an Eclipse treatment planning system and a 2D x-ray digital image using an on-board digital imaging patient setup (DIPS) system in the proton treatment room. In the DIPS system, the patient position can be manually adjusted based on two orthogonal x-ray images.
In addition, a balloon was inserted into the rectum of each patient and filled with 100 ml water. For each patient, the clinical target volume (CTV) was defined as the whole prostate with involved seminal vesicles, and the planning target volume (PTV) was designed to be a uniform 10 mm expansion around the CTV. The DVH showed that the rectal volume received a mean of 20% to 40% of the prescribed dose.
대상 데이터
Table 1. Displacement of prostate target volume relative to initial location, based on an analysis of 38 coronal images of 10 prostate cancer patients.
이론/모형
10. Depth variations of prostate volume for 10 proton patients based on the automated depth determination method.
8. Difference in data acquired using the automated depth determination and manual methods.
성능/효과
2 mm in the y-direction. Based on the analysis of 10 patients, the mean differences in prostate location between the reference and test images in the x and y directions were 0.9 mm and 2.3 mm, respectively, and the maximum discrepancies were 3.3 mm and 7.2 mm, respectively. The data for displacement in the x-direction, i.
2 mm, respectively. The data for displacement in the x-direction, i.e., the depth changes, shows that 42.1%, 26.3% and 2.6% in 38 image comparisons showed greater than 1 mm, 2 mm and 3 mm depth differences, respectively, between the planning and treatment stages. Fig.
8 shows a comparison for depth changes between the automatic method and a manual method. The mean difference between the two methods was less than 1.0 mm, with a less than 1 mm standard deviation, indicating that the proposed method can effectively determine the depth of the prostate target volume.
참고문헌 (13)
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Mah D, Freedman G, Milestone B, et al: Measurement of intra-fractional prostate motion using magnetic resonance imaging. Int J Radiat Oncol Biol Phys 54:568-575 (2002)
Soete G, De Cock M, Verellen D, Michielsen D, Keuppens F, Storme G: X-ray-assisted positioning of patients treated by conformal arc radiotherapy for prostate cancer: comparison of setup accuracy using implanted markers versus bony structures. Int J Radiat Oncol Biol Phys 67:823-827 (2007)
Kitamura K, Shirato H, Seppenwoolde Y, et al: Three-dimensional intrafractional movement of prostate measured during real-time tumor-tracking radiotherapy in supine and prone treatment positions. Int J Radiat Oncol Biol Phys 53:1117-1123 (2002)
Schallenkamp JM, Herman MG, Kruse JJ, Pisansky TM: Prostate position relative to pelvic bony anatomy based on intraprostatic gold markers and electronic portal imaging. Int J Radiat Oncol Biol Phys 63:800-811 (2005)
Zhang X, Dong L, Lee A, et al: Effect of anatomic motion on proton therapy dose distributions in prostate cancer treatment. Int J Radiat Oncol Biol Phys 67:620-629 (2007)
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