영상유도 양성자치료를 위한 콘빔 CT 재구성 알고리즘: 기하학적 보정방법에 관한 연구 = Geometric Calibration of Cone-beam CT System for Image Guided Proton Therapy

다국어 초록 (Multilingual Abstract)

According to improved radiation therapy technology such as IMRT and proton therapy, the accuracy of patient alignment system is more emphasized and IGRT is dominated research field in radiation oncology. We proposed to study the feasibility of cone-beam CT system using simple x-ray imaging systems for image guided proton therapy at National Cancer Center. 180 projection views ($2,304{\times}3,200$, 14 bit with 127 ${\mu}m$ pixel pitch) for the geometrical calibration phantom and humanoid phantoms (skull, abdomen) were acquired with $2^{\circ}$ step angle using x-ray imaging system of proton therapy gantry room ($360^{\circ}$ for 1 rotation). The geometrical calibration was performed for misalignments between the x-ray source and the flat-panel detector, such as distances and slanted angle using available algorithm. With the geometrically calibrated projection view, Feldkamp cone-beam algorithm using Ram-Lak filter was implemented for CBCT reconstruction images for skull and abdomen phantom. The distance from x-ray source to the gantry isocenter, the distance from the flat panel to the isocenter were calculated as 1,517.5 mm, 591.12 mm and the rotated angle of flat panel detector around x-ray beam axis was considered as $0.25^{\circ}$. It was observed that the blurring artifacts, originated from the rotation of the detector, in the reconstructed toomographs were significantly reduced after the geometrical calibration. The demonstrated CBCT images for the skull and abdomen phantoms are very promising. We performed the geometrical calibration of the large gantry rotation system with simple x-ray imaging devices for CBCT reconstruction. The CBCT system for proton therapy will be used as a main patient alignment system for image guided proton therapy.

참고문헌 (Reference)

1 Bissonnette JP, "Quality assurance for the geometric accuracy of cone-beam CT guidance in radiation therapy" 71 : S57-S61, 2008

2 Brada M, "Proton therapy in clinical practice: current clinical evidence" 25 (25): 965-970, 207

3 Smith AR, "Proton therapy" 51 (51): R491-R504, 2006

4 MacDonald SM, "Proton beam radiation therapy" 24 (24): 199-208, 2006

5 Kak AC, "Principles of computerized tomographic imaging. in SIAM" 2001

6 Guckenberger M, "Precision of image-guided radiotherapy (IGRT) in six degrees of freedom and limitations in clinical practice" 183 (183): 307-313, 2007

7 Feldkamp LA, "Practical cone-beam algorithm" 1 (1): 612-619, 1984

8 Moyers MF, "Point/Counterpoint. Protontherapy is the best radiation treatment modality for prostate cancer" 342 (342): 375-378, 2007

9 Karellas A, "Point/Counterpoint. Cone beam x-ray CT will be superior to digital x-ray tomosynthesis in imaging the breast and delineating cancer" 35 (35): 409-411, 2008

10 Brada M, "Pijls-Johannesma M: Evidence for Proton Therapy" 2008

11 Sawada A, "Patient positioning method based on binary image correlation between two edge images for proton-beam radiation therapy" 32 (32): 3106-3111, 2005

12 Xing L, "Overview of image-guided radiation therapy" 31 (31): 91-112, 2006

13 Wu QJ, "On-board patient positioning for head-and-neck IMRT: comparing digital tomosynthesis to kilovoltage radiography and cone-beam computed tomography" 69 (69): 598-606, 2007

14 Bachar G, "Image quality and localization accuracy in C-arm tomosynthesis- guided head and neck surgery" 34 (34): 4664-4677, 2007

15 Daly MJ, "Geometric calibration of a mobile C-arm for intraoperative cone-beam CT" 35 (35): 2124-2136, 2008

16 Godfrey DJ, "Evaluation of three types of reference image data for external beam radiotherapy target localization using digital tomosynthesis (DTS)" 34 (34): 3374-3384, 2007

17 Song WY, "Evaluation of image-guided radiation therapy (IGRT) technologies and their impact on the outcomes of hypofractionated prostate cancer treatments: a radiobiologic analysis" 64 (64): 289-300, 2006

18 Dobbins JT 3rd, "Digital x-ray tomosynthesis: current state of the art and clinical potential" 48 (48): R65-R106, 2003

19 Godfrey DJ, "Digital tomosynthesis with an on-board kilovoltage imaging device" 65 (65): 8-15, 2006

20 Kim HK, "Cone-beam microtomography and its applications" 22 (22): 7-14, 2005

21 Dawson LA, "Advances in image-guided radiation therapy" 25 (25): 938-946, 2007

22 Cho Y, "Accurate technique for complete geometric calibration of cone-beam computed tomography systems" 32 (32): 968-983, 2005

23 Yan H, "Accelerating reconstruction of reference digital tomosynthesis using graphics hardware" 34 (34): 3768-3776, 2007

24 Amies C, "A multi-platform approach to image guided radiation therapy (IGRT)" 31 (31): 12-19, 2006