491 原著 kv-cbct 川村哲朗 2 宮脇大輔 1 村上直基 1 木村邦彦 1 岡村佳明土師 1 守 2 西村英輝 2 佐々木良平 Code No 緒言 image-guided radiation therapy: IGRT kv

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1 49 原著 kv-cbct 川村哲朗 2 宮脇大輔村上直基木村邦彦岡村佳明土師守 2 西村英輝 2 佐々木良平 Code No 緒言 image-guided radiation therapy: IGRT kv cone-beam computed tomography kv-cbct, 2 kv-cbct CT dose index CTDI thermoluminescent dosimeter TLD 3 5, 6 7, 8 kv-cbct kv-cbct radiotherapy planning system: RTPS) kv-cbct Evaluation of Absorbed Dose from Kilovoltage Cone-beam Computed Tomography by Radiotherapy Planning System: Influence on the Radiation Therapy for Prostate Cancer Tetsuro Kawamura, Naoki Murakami, Yoshiaki Okamura, Hideki Nishimura, 2 Daisuke Miyawaki, 2 Kunihiko Kimura, Mamoru Hase, and Ryohei Sasaki 2 Department of Radiology, Kakogawa West City Hospital 2 Division of Radiation Oncology, Kobe University Graduate School of Medicine Received March 27, 202; Revision accepted March 2, 203 Code No. 754 Summary Image-guided radiation therapy (IGRT) is increasingly being used in modern radiation therapy, and it is now possible to verify a patient s position using kilo-voltage cone-beam computed tomography (kv-cbct). However, if kv-cbct is used frequently, the dose absorbed by the body cannot be disregarded. A number of studies have been made on the absorbed dose of kv-cbct, in which absorbed dose measurements were made using a computed tomography dose index (CTDI) or a thermoluminescent dosimeter (TLD). Other methods include comparison of the absorbed dose between a kv-cbct and other modalities. These techniques are now in common use. However, dose distribution within the patient varies with the patient s size, posture and the part of the body to which radiation therapy is applied. The chief purpose of this study was to evaluate the dose distribution of kv-cbct by employing a radiotherapy planning system (RTPS); a secondary aim was to examine the influence of a dose of kv-cbct radiation when used to treat prostate cancer. The beam data of an on-board imager (OBI) was registered in the RTPS, after which modeling was performed. The radiation dosimetry was arranged by the dosimeter in an elliptical phantom. Rotational radiation treatment was used to obtain the dose distribution of the kv-cbct within the patient, and the patient dose was evaluated based on the simulation of the dose distribution. In radiation therapy for prostate cancer, if kv-cbct was applied daily, the dose increment within the planning target volume (PTV) and the organ in question was about Gy. Key words: image-guided radiation therapy, kilovoltage cone-beam computed tomography, absorbed dose, dose distribution *Proceeding author Vol. 69 No. 5 May 203

2 492. 方法 - X X-ray simulator Varian Medical Systems Clinac-ix X on-board imager OBI version.4 half bow-tie filter X 0 gantry 90 6 cc Radcal half value layer: HVL HVL 50 Radcal Model 905 Radiation Monitor Controller 9 isocenter X isocenter GAMMEX RMI RMI5A 99 X X 25 kv 80 ma 00 ms 3 3 cm HVL 0 Fig. -2 kv-cbct kv-cbct Mode Name Pelvis kv 80 ma 3 ms 680 ma second mas half bow-tie filter + IBA Dosimetry I mrt Phantom Isocenter PTW-Freiburg 0.6 cc Farmer chamber type 3003 kv-cbct X=6.8 cm X2=23.5 cm Y=Y2=5.4 cm long 8 cm - 0, D med=x out F K (W air/e) (μ en/ρ) water/(μ en/ρ) air X out F K W air W ev (μ en/ρ) water (μ en/ρ) air Fig. Geometry of the half-value layer s measurement. Radcal 6 cc F X 25 kv 80 ma 00 ms 0 0 cm 6 cc 0.6 cc Farmer chamber isocenter quality index half bow-tai filter -3 X percent depth dose: PDD off-center ratio: OCR PTW-Freiburg MP PTW-Freiburg 0.25 cc Semiflex chamber type300 PTW-Freiburg 0.35 cc Roos chamber type3400 PTW-Freiburg UNIDOS webline PTW-Freiburg MEPHYSTO mc 2 MP X X X PDD kv-cbct 25 kv 80 ma half bow-tie filter + SSD 00 cm 0 ms PTW300 Semiflex PTW 3400 Roos PTW 3400 Roos PDD 0 mm mm cm OCR 25 kv 80 ma 00 ms 0 PTW300 Semiflex

3 cm JIS MP OCR X Y cm cm -4 Philips Medical Systems Pinnacle 3 Version 8.0 m clarkson convolution superposition wedge half bow-tie filter wedge auto-modeling manual half bow-tie filter -5 kv-cbct monitor unit MU kv-cbct -2 MU kv-cbct MU fraction size kv-cbct -6 CT kv-cbct PDD OCR kv-cbct -2 PTW 3003 farmer kv-cbct Fig. 2 4 Fig. 2 PTW 3003 farmer CT MU -5 Fig. 2 Measurement points in the elliptical phantom. -7 CT kv-cbct intensity modulated radiation therapy: IMRT dose volume histogram DVH D95% 74 Gy/37 fr kv-cbct 結果 2- kv-cbct kv-cbct 25 kv 80 ma 00 ms half bow-tie filter mm 44.9 kev quality index mm kv-cbct cgy 2-2 OBI OBI PDD OCR Fig. 3 4 Crossplane half bow-tie filter PDD OCR half bow-tie filter Vol. 69 No. 5 May 203

4 494 Fig. 3 PDD curve of the X-ray simulator in the water phantom. Fig. 5 The shape of the half bow-tie filter registered in the RTPS. Fig. 6 Comparison of the PDD between measurement of the X-ray simulator and the modeling results of the RTPS. Fig. 4 OCR curves of the X-ray simulator in the water phantom. Table PDD OCR -5 kv-cbct MU calibration point dose/mu 0.0 cgy/mu 473 MU MU Fig. 0 Table 2 ±2 Fig. 5 PDD Fig. 6 depth cm OCR Fig. 7 PDD depth PDD OCR Fig. 8 9 PDD RTPS 2-5 A B C kv-cbct Fig. 2 kv-cbct Table 3 kv-cbct kv-cbct maximum dose cgy

5 495 Fig. 7 Comparison of the OCR between measurement of the X-ray simulator and the modeling results of the RTPS. Fig. 8 Comparison of the PDD between measurement of the X-ray simulator and calculation results of the RTPS. Fig. 9 Comparison of the OCR between measurement of the X-ray simulator and calculation results of the RTPS. Vol. 69 No. 5 May 203

496 Table Relative error of the PDD between measurement of the X-ray simulator and calculation results of the RTPS Measurement depth (cm) 0.0 0.

The kv-cbct dose distribution was calculated by RTPS. Table 2.0 Fig. 3.0 4.0 7.0 0.0 3.0 6.0 9.0 2.0 0.77 0.43 0.0 0.82.34.39.2 0.

72 3.73 2.06 2.07 2.37±0.04 2.85±0.04 2.82±0.04 2.30±0.0 2.27±0.0 3.66±0.0 3.36±0.0 2.06±0.02 2.05±0.0 0.00 0.

6 496 Table Relative error of the PDD between measurement of the X-ray simulator and calculation results of the RTPS Measurement depth (cm) Error (%) Fig Measurement point Simulation dose (cgy) Measurement dose (cgy) Error (%) Dose distribution in the elliptical phantom. The kv-cbct dose distribution was calculated by RTPS. Table 2.0 Fig Proﬁle curve of dose distribution in the elliptical phantom. Measurement values in the elliptical phantom ① ② ③ ④ ⑤ ⑥ ⑦ ⑧ ⑨ ± ± ± ± ± ± ± ± ± Comparison of the absorbed dose between measured values and simulated values. Fig. 2 Dose distribution in the pelvis. The kv-cbct dose distribution was calculated by RTPS. 日本放射線技術学会雑誌

497 Table 3 The kv-cbct dose in the pelvis, when the kv-cbct was used once Patient s physique A B C Maximum dose Bladder 3.9 3.4.7 (cgy) Rectum 3.2 3..9 PTV 3. 2.6.8 Mean dose Bladder 2.9 2.4.3 (cgy) Rectum 2.

7 497 Table 3 The kv-cbct dose in the pelvis, when the kv-cbct was used once Patient s physique A B C Maximum dose Bladder (cgy) Rectum PTV Mean dose Bladder (cgy) Rectum PTV Fig. 3 Dose distribution in the pelvis. Comparison of the dose distribution between IMRT and IMRT+kV-CBCT. Fig. 4 Comparison of the dose volume histogram between IMRT and IMRT+kV-CBCT. Table 4 Comparison of the absorbed dose between IMRT and IMRT+kV-CBCT Bladder Rectum PTV Maximum dose IMRT (cgy) IMRT+kV-CBCT (cgy) Dose increment (cgy) Percentage increase (%)... Mean dose IMRT (cgy) IMRT+kV-CBCT (cgy) Dose increment (cgy) Percentage increase (%) D95% 74 Gy cgy planning target volume: PTV.8 3. cgy B IMRT IMRT+kV-CBCT DVH Fig. 3 4 Table 4 kv-cbct PTV maximum dose 82.4 cgy 85.7 cgy 90. cgy Vol. 69 No. 5 May 203

8 498 mean dose 90.0 cgy 92.3 cgy 88.3 cgy 3. 考察 HVL Song 5 PDD depth Fig. 6 OBI 0. MeV Fig. 8 9 RTPS kv-cbct OCR Fig. 4 crossplane half bow-tie filter crossplane 2 CT 320 mm 0. CT kv-cbct half bow-tie filter kv-cbct Table 2 Fig. ±2 Table 2 contouring PTV MV kv Fig. 0 kv MV CT Fig. 2 A B C kv-cbct CT X kv-cbct Fig. 2 Table 3 Ding 3 kv-cbct X 4 RTPS Ding 25 kv 80 ma 25 ms X=8.3 cm X2=24.9 cm Y=Y2=.8 cm 4 cgy RTPS 25 kv 80 ma 3 ms X=6.8 cm X2=23.5 cm Y=Y2=5.4 cm PTV cgy kv-cbct PTV Table 4 maximum dose PTV. mean dose 3. Michalski 4 60 Gy 45 Gy 3D-CRT IMRT V50<50 V60<35 V70<20 V75<5 Viswanathan 5 V80<5 V75<25 V70<35 V65<30

9 499 kv-cbct kv-cbct kv-cbct adaptive radiotherapy kv-cbct kv-cbct kv-cbct kv-cbct IGRT 4. 結語 OBI kv-cbct IMRT kv-cbct IMRT kv-cbct kv-cbct kv-cbct kv-cbct kv-cbct 謝辞参考文献 FPD 2009; 65(6): FPD On Board Imager 2009; 65(6): Wen N, Guan H, Hammoud R, et al. Dose delivered from Varian s CBCT to patients receiving IMRT for prostate cancer. Phys Med Biol 2007; 52(8): Amer A, Marchant T, Sykes J, et al. Imaging doses from the Elekta Synergy X-ray cone beam CT system. Br J Radiol 2007; 80(954): Song WY, Kamath S, Ozawa S, et al. A dose comparison study between XVI and OBI CBCT systems. Med Phys 2008; 35(2): Hyer DE, Serago CF, Kim S, et al. An organ and effective dose study of XVI and OBI cone-beam CT system. J Appl Clin Med Phys 200; (2): Kim S, Yoshizumi TT, Toncheva G, et al. Comparison of radiation doses between cone beam CT and multi detector CT: TLD measurements. Radiat Prot Dosimetry 2008; 32(3): IMRT CBCT 20; 67(3): X 2002; 58(3): X CT 2003; 59(8): CT 200; 57(): Ding GX, Duggan DM, Coffey CW. Accurate patient dosimetry of kilovoltage cone-beam CT in radiation therapy. Med Phys 2008; 35(3): Michalski JM, Gay H, Jackson A, et al. Radiation dose-volume effects in radiation-induced rectal injury. Int J Radiat Oncol Biol Phys 200; 76(3 Suppl): S23-S29. 5 Viswanathan AN, Yorke ED, Marks LB, et al. Radiation dose-volume effects of the urinary bladder. Int J Radiat Oncol Biol Phys 200; 76(3 Suppl): S6-S Vol. 69 No. 5 May 203

753 原著 Code No. 490 kv-cone beam CT 1, 2 河野友宏 3 荒木不次男 4 中口裕二大野 3 剛緒言 intensity modulated radiotherapy: IMRT volumetric

753 原著 Code No. 490 kv-cone beam CT 1, 2 河野友宏 3 荒木不次男 4 中口裕二大野 3 剛緒言 intensity modulated radiotherapy: IMRT volumetric 753 原著 2012 10 27 2013 5 21 de No. 490 kv-cone beam CT 1, 2 河野友宏 3 荒木不次男 4 中口裕二 1 2 3 4 大野 3 剛緒言 intensity modulated radiotherapy: IMRT volumetric modulated arc radiotherapy: VMAT image-guided radiotherapy:

491 原著 kv-cbct 川村哲朗 2 宮脇大輔 1 村上直基 1 木村邦彦 1 岡村佳明 土師 1 守 2 西村英輝 2 佐々木良平 Code No 緒言 image-guided radiation therapy: IGRT kv

491 原著 kv-cbct 川村哲朗 2 宮脇大輔 1 村上直基 1 木村邦彦 1 岡村佳明土師 1 守 2 西村英輝 2 佐々木良平 Code No 緒言 image-guided radiation therapy: IGRT kv