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Song JY, Chie EK, Kang SH, Jeon YJ, Ko YA, Kim DY, Kang HC. Dosimetric evaluation of magnetic resonance imaging-guided adaptive radiation therapy in pancreatic cancer by extent of re-contouring of organs-at-risk. Radiat Oncol J 2022; 40:242-250. [PMID: 36606301 PMCID: PMC9830039 DOI: 10.3857/roj.2022.00332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 11/14/2022] [Indexed: 12/27/2022] Open
Abstract
PURPOSE The safety of online contouring and planning for adaptive radiotherapy is unknown. This study aimed to evaluate the dosimetric difference of the organ-at-risk (OAR) according to the extent of contouring in stereotactic magnetic resonance image-guided adaptive RT (SMART) for pancreatic cancer. MATERIALS AND METHODS We reviewed the treatment plan data used for SMART in patients with pancreatic cancer. For the online contouring and planning, OARs within 2 cm from the planning target volume (PTV) in the craniocaudal direction were re-controlled daily at the attending physician's discretion. The entire OARs were re-contoured retrospectively for data analysis. We termed the two contouring methods the Rough OAR and the Full OAR, respectively. The proportion of dose constraint violation and other dosimetric parameters was analyzed. RESULTS Nineteen patients with 94 fractions of SMART were included in the analysis. The dose constraint was violated in 10.6% and 43.6% of the fractions in Rough OAR and Full OAR methods, respectively (p = 0.075). Patients with a large tumor, a short distance from gross tumor volume (GTV) to OAR, and a tumor in the body or tail were associated with more occult dose constraint violations-large tumor (p = 0.027), short distance from GTV to OAR (p = 0.061), tumor in body or tail (p = 0.054). No dose constraint violation occurred outside 2 cm from the PTV. CONCLUSION More occult dose constraint violations can be found by the Full OAR method in patients with pancreatic cancer with some clinical factors in the online re-planning for SMART. Re-contouring all the OARs would be helpful to detect occult dose constraint violations in SMART planning. Since the dosimetric profile of SMART cannot be represented by a single fraction, patient selection for the Full OAR method should be weighted between the clinical usefulness and the time and workforce required.
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Affiliation(s)
- Jun Yeong Song
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea,Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Korea
| | - Eui Kyu Chie
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea,Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Korea
| | - Seong-Hee Kang
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea
| | - Yeon-Jun Jeon
- Seoul National University College of Medicine, Seoul, Korea
| | - Yoon-Ah Ko
- Seoul National University College of Medicine, Seoul, Korea
| | - Dong-Yun Kim
- Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Korea,Department of Radiation Oncology, Kyung Hee University Hospital at Gangdong, Seoul, Korea
| | - Hyun-Cheol Kang
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea,Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Korea,Correspondence: Hyun-Cheol Kang Department of Radiation Oncology, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul 03080, Korea. Tel: +82-2-2072-2526 E-mail:
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Sharma M, Nano TF, Akkati M, Milano MT, Morin O, Feng M. A systematic review and meta-analysis of liver tumor position variability during SBRT using various motion management and IGRT strategies. Radiother Oncol 2021; 166:195-202. [PMID: 34843841 DOI: 10.1016/j.radonc.2021.11.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 11/17/2021] [Accepted: 11/21/2021] [Indexed: 12/25/2022]
Abstract
PURPOSE To suggest PTV margins for liver SBRT with different motion management strategies based on a systematic review and meta-analysis. METHODS In accordance with Preferred-Reporting-Items-for-Systematic-Reviews-and-Meta-Analyses (PRISMA), a systematic review in PubMed, Embase and Medline databases was performed for liver tumor position variability. From an initial 533 studies published before October 2020, 36 studies were categorized as 18 free-breathing (FB; npatients = 401), 9 abdominal compression (AC; npatients = 145) and 9 breath-hold (BH; npatients = 126). A meta-analysis was performed on inter- and intra-fraction position variability to report weighted-mean with 95% confidence interval (CI95) in superior-inferior (SI), left-right (LR) and anterior-posterior (AP) directions. Furthermore, weighted-mean ITV margins were computed for FB (nstudies = 15, npatients = 373) and AC (nstudies = 6, npatients = 97) and PTV margins were computed for FB (nstudies = 6, npatients = 95), AC (nstudies = 7, npatients = 106) and BH (nstudies = 8, npatients = 133). RESULTS The FB weighted-mean intra-fraction variability, ITV margins and weighted-standard-deviation in mm were SI-9.7, CI95 = 9.3-10.1, 13.5 ± 4.9; LR-5.4, CI95 = 5.3-5.6, 7.3 ± 7.9; and AP-4.2, CI95 = 4.0-4.4, 6.3 ± 7.6. The inter-fraction-based results were SI-4.7, CI95 = 4.3-5.1, 5.7 ± 1.7; LR-1.4, CI95 = 1.1-1.6, 3.6 ± 2.7; and AP-2.8, CI95 = 2.5-3.1, 4.8 ± 2.1. For AC intra-fraction results in mm were SI-1.8, CI95 = 1.6-2.0, 2.6 ± 1.2; LR-0.7, CI95 = 0.6-0.8, 1.7 ± 1.5; and AP-0.9, CI95 = 0.8-1.0, 1.9 ± 1.7. The inter-fraction results were SI-2.6, CI95 = 2.3-3.0, 5.2 ± 2.9; LR-1.9, CI95 = 1.7-2.1, 4.0 ± 2.2; and AP-2.9, CI95 = 2.5-3.2, 5.8 ± 2.7. For BH the inter-fraction variability, and the weighted-mean PTV margins and weighted-standard-deviation in mm were SI-2.4, CI95 = 2.1-2.7, 5.6 ± 2.9; LR-1.8, CI95 = 1.3-2.2, 5.5 ± 1.7; and AP-1.4; CI95 = 1.2-1.7, 6.1 ± 2.1. CONCLUSION Our meta-analysis suggests a symmetric weighted-mean PTV margin of 6 mm might be appropriate for BH. For AC and FB, asymmetric PTV margins (weighted-mean margin of 4 mm (AP), 6 mm (SI/LR)) might be appropriate. For FB, if larger (>ITV margin) intra-fraction variability observed, the additional intra- and inter-fraction variability should be accounted in the PTV margin.
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Affiliation(s)
- Manju Sharma
- University of California, San Francisco, United States.
| | - Tomi F Nano
- University of California, San Francisco, United States
| | | | | | - Olivier Morin
- University of California, San Francisco, United States
| | - Mary Feng
- University of California, San Francisco, United States
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Uchinami Y, Katoh N, Abo D, Taguchi H, Yasuda K, Nishioka K, Soyama T, Morita R, Miyamoto N, Suzuki R, Sho T, Nakai M, Ogawa K, Kakisaka T, Orimo T, Kamiyama T, Shimizu S, Aoyama H. Treatment outcomes of stereotactic body radiation therapy using a real-time tumor-tracking radiotherapy system for hepatocellular carcinomas. Hepatol Res 2021; 51:870-879. [PMID: 33894086 DOI: 10.1111/hepr.13649] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/07/2021] [Accepted: 04/17/2021] [Indexed: 01/07/2023]
Abstract
AIM To report the outcomes of stereotactic body radiotherapy using a real-time tumor-tracking radiotherapy system for hepatocellular carcinoma patients. METHODS From January 2005 to July 2018, 63 patients with 74 lesions with a maximum diameter ≤52 mm were treated by stereotactic body radiotherapy using a real-time tumor-tracking radiotherapy system. No patient with a Child-Pugh Score ≥9 was included, and 85.6% had a score of 5 or 6. Using the biological effective dose (BED) with an α/β ratio of 10 (BED10 ), the median dose in BED10 at the reference point was 76.8 Gy (range 60-122.5 Gy). Overall survival (OS) and local control rates were assessed using the Kaplan-Meier method. RESULTS With a median follow-up period of 24.6 months (range 0.9-118.4 months), the 1-year and 2-year OS rates were 86.8% (95% confidence interval [95% CI] 75.8-93.3) and 71.1% (57.8-81.6), respectively. The 2-year OS was 89.6% in patients with the baseline modified albumin-bilirubin (mALBI) grade =1, and 61.7% in patients with grade ≥2a. In the multivariate analysis, the mALBI grade (=1 vs. ≥2a) was a significant factor for OS (p = 0.028, 95% CI 1.11-6.18). The 1-year and 2-year local control rates were 100% (100-100%) and 92.0% (77.5-97.5%). The local control rates were significantly higher in the BED10 ≥100 Gy group than in the BED10 <100 Gy group (2-year 100% vs. 86.5%, p = 0.049) at the reference point. CONCLUSION This retrospective study of stereotactic body radiotherapy using real-time tumor-tracking radiotherapy for hepatocellular carcinoma showed favorable outcomes with lower incidence of toxicities, especially in patients treated with BED10 ≥100 Gy to the reference point.
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Affiliation(s)
- Yusuke Uchinami
- Department of Radiation Oncology, Faculty of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Norio Katoh
- Department of Radiation Oncology, Faculty of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Daisuke Abo
- Department of Diagnostic and Interventional Radiology, Hokkaido University Hospital, Sapporo, Hokkaido, Japan
| | - Hiroshi Taguchi
- Department of Radiation Oncology, Hokkaido University Hospital, Sapporo, Hokkaido, Japan
| | - Koichi Yasuda
- Department of Radiation Oncology, Hokkaido University Hospital, Sapporo, Hokkaido, Japan
| | - Kentaro Nishioka
- Department of Radiation Medical Science and Engineering, Faculty of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Takeshi Soyama
- Department of Diagnostic and Interventional Radiology, Hokkaido University Hospital, Sapporo, Hokkaido, Japan
| | - Ryo Morita
- Department of Diagnostic Imaging, Faculty of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Naoki Miyamoto
- Department of Medical Physics, Hokkaido University Hospital, Sapporo, Hokkaido, Japan
| | - Ryusuke Suzuki
- Department of Medical Physics, Hokkaido University Hospital, Sapporo, Hokkaido, Japan
| | - Takuya Sho
- Department of Gastroenterology and Hepatology, Faculty of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Masato Nakai
- Department of Gastroenterology and Hepatology, Faculty of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Koji Ogawa
- Department of Gastroenterology and Hepatology, Faculty of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Tatsuhiko Kakisaka
- Department of Gastroenterological Surgery I, Faculty of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Tatsuya Orimo
- Department of Gastroenterological Surgery I, Faculty of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Toshiya Kamiyama
- Department of Gastroenterological Surgery I, Faculty of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Shinichi Shimizu
- Department of Radiation Medical Science and Engineering, Faculty of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Hidefumi Aoyama
- Department of Radiation Oncology, Faculty of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
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Matrosic CK, Culberson W, Shepard A, Jupitz S, Bednarz B. 3D dosimetric validation of ultrasound-guided radiotherapy with a dynamically deformable abdominal phantom. Phys Med 2021; 84:159-167. [PMID: 33901860 DOI: 10.1016/j.ejmp.2021.04.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 03/01/2021] [Accepted: 04/06/2021] [Indexed: 12/25/2022] Open
Abstract
OBJECTIVES The purpose of this study was to dosimetrically benchmark gel dosimetry measurements in a dynamically deformable abdominal phantom for intrafraction image guidance through a multi-dosimeter comparison. Once benchmarked, the study aimed to perform a proof-of-principle study for validation measurements of an ultrasound image-guided radiotherapy delivery system. METHODS The phantom was dosimetrically benchmarked by delivering a liver VMAT plan and measuring the 3D dose distribution with DEFGEL dosimeters. Measured doses were compared to the treatment planning system and measurements acquired with radiochromic film and an ion chamber. The ultrasound image guidance validation was performed for a hands-free ultrasound transducer for the tracking of liver motion during treatment. RESULTS Gel dosimeters were compared to the TPS and film measurements, showing good qualitative dose distribution matches, low γ values through most of the high dose region, and average 3%/5 mm γ-analysis pass rates of 99.2%(0.8%) and 90.1%(0.8%), respectively. Gel dosimeter measurements matched ion chamber measurements within 3%. The image guidance validation study showed the measurement of the treatment delivery improvements due to the inclusion of the ultrasound image guidance system. Good qualitative matching of dose distributions and improvements of the γ-analysis results were observed for the ultrasound-gated dosimeter compared to the ungated dosimeter. CONCLUSIONS DEFGEL dosimeters in phantom showed good agreement with the planned dose and other dosimeters for dosimetric benchmarking. Ultrasound image guidance validation measurements showed good proof-of-principle of the utility of the phantom system as a method of validating ultrasound-based image guidance systems and potentially other image guidance methods.
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Affiliation(s)
- Charles K Matrosic
- School of Medicine and Public Health, Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, United States.
| | - Wesley Culberson
- School of Medicine and Public Health, Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, United States
| | - Andrew Shepard
- School of Medicine and Public Health, Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, United States
| | - Sydney Jupitz
- School of Medicine and Public Health, Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, United States
| | - Bryan Bednarz
- School of Medicine and Public Health, Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, United States
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Afzalifar A, Mowlavi AA, Mohammadi M. Performance of a linear accelerator couch positioning quality control task using an electronic portal imaging device. Radiol Phys Technol 2020; 13:195-200. [PMID: 32078138 DOI: 10.1007/s12194-020-00557-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 02/10/2020] [Accepted: 02/11/2020] [Indexed: 10/25/2022]
Abstract
Short and semi-automated quality assurance (QA) programs are becoming one of the most popular and highly demanding tasks in radiotherapy. The current research investigates the accuracy of a four degrees of freedom (4DoF) medical linear accelerator couch positioning with a fast and accurate method based on images acquired using an electronic portal imaging device (EPID). An accurate EPID QA phantom and a proper in-house code were used. A Siemens medical linear accelerator equipped with an a-Si EPID was used to acquire portal images. For verifying the mechanical performance of the EPID positioning, EPID sensitivity, and accuracy of the code response from the image processing point of view were investigated. To characterize the results, three deviations in the phantom positioning were deliberately created. The translational and rotational displacements of the treatment couch were then evaluated. The loading effect on the treatment couch was then investigated. The results of prerequisite tests, including the mechanical performance of the EPID, and the sensitivity and accuracy of the recognition codes, were assessed. The results were found to be within the tolerance range reported at AAPM TG-142. The mean deviations of the tests between expected and measured displacements by 4DoF treatment couch were found to be 0.13° ± 0.11°, 0.12 ± 0.17 mm, 0.17 ± 0.13 mm, and 0.04 ± 0.09 mm for rotational, longitudinal, lateral, and vertical shifts, respectively. The results showed that the proposed method is a reliable and fast approach to find the uncertainties occurring intreatment couch positioning.
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Affiliation(s)
- A Afzalifar
- Physics Department, School of Sciences, Hakim Sabzevari University, Sabzevar, Iran
| | - A A Mowlavi
- Physics Department, School of Sciences, Hakim Sabzevari University, Sabzevar, Iran.,ICTP, Associate Federation Scheme,, Medical Physics Field, Trieste, Italy
| | - M Mohammadi
- Department of Medical Physics, Royal Adelaide Hospital, Adelaide, SA, 5000, Australia. .,School of Physical Sciences, The University of Adelaide, Adelaide, SA, 5005, Australia.
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CyberKnife MLC-based treatment planning for abdominal and pelvic SBRT: Analysis of multiple dosimetric parameters, overall scoring index and clinical scoring. Phys Med 2018; 56:25-33. [DOI: 10.1016/j.ejmp.2018.11.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 11/13/2018] [Accepted: 11/17/2018] [Indexed: 12/31/2022] Open
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Kurosu K, Sumida I, Suzuki O, Shiomi H, Ota S, Otani K, Tamari K, Seo Y, Ogawa K. Dosimetric and clinical effects of interfraction and intrafraction correlation errors during marker-based real-time tumor tracking for liver SBRT. JOURNAL OF RADIATION RESEARCH 2018; 59:164-172. [PMID: 29253275 PMCID: PMC5951116 DOI: 10.1093/jrr/rrx067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 09/13/2017] [Indexed: 06/07/2023]
Abstract
Correlation model error (CME) between the internal target and the external surrogate, and marker-tumor correlation error (MTCE) between the tumor and the implanted marker occur during marker-based real-time tumor tracking. The effects of these intrafraction and interfraction errors on the dose coverage in the clinical target volume (CTV) and on tumor control probability (TCP) for hepatocellular carcinoma (HCC) were evaluated in this study. Eight HCC patients treated with non-isocentric dose delivery by a robotic radiosurgery system were enrolled. The CMEs were extracted from the treatment log file, and the MTCEs were calculated from the preceding study. The CMEs and MTCEs were randomly added to each beam's robot position, and the changes in the TCP and the 2%, 95% and 99% dose coverage values for the CTV (D2, D95 and D99) were simulated. The data were statistically analyzed as a function of the CTV to planning target volume (PTV) margin, the dose fraction and the marker-tumor distance. Significant differences were observed in the majority of the CTV D2, D95 and D99 values and the TCP values. However, a linear regression revealed that ∆CTV D2, D95 and D99 have a weak correlation with ∆TCP. A dose-difference metric would be unable to detect a critical error for tumor control if the coverage changes for the CTV and ∆TCP were weakly correlated. Because the simulated TCP-based parameter determination was based on the dose simulation, including predicted interfraction and intrafraction errors, we concluded that a 95th percentile TCP-based parameter determination would be a robust strategy for ensuring tumor control while reducing doses to normal structures.
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Affiliation(s)
- Keita Kurosu
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
- Department of Radiology, Osaka University Hospital, 2-15 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Iori Sumida
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Osamu Suzuki
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Hiroya Shiomi
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Seiichi Ota
- Department of Radiology, Osaka University Hospital, 2-15 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Keisuke Otani
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Keisuke Tamari
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yuji Seo
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Kazuhiko Ogawa
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
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Hu Y, Zhou YK, Chen YX, Zeng ZC. Magnitude and influencing factors of respiration-induced liver motion during abdominal compression in patients with intrahepatic tumors. Radiat Oncol 2017; 12:9. [PMID: 28073377 PMCID: PMC5223487 DOI: 10.1186/s13014-016-0762-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 12/30/2016] [Indexed: 12/26/2022] Open
Abstract
PURPOSE The purpose of this study was to use 4-dimensional-computed tomography (4D-CT) to evaluate respiration-induced liver motion magnitude and influencing factors in patients with intrahepatic tumors undergoing abdominal compression. METHODS From January 2012 to April 2016, 99 patients with intrahepatic tumors were included in this study. They all underwent 4D-CT to assess respiratory liver motion. This was performed during abdominal compression in 53 patients and during free-breathing (no abdominal compression) in 46 patients. We defined abdominal compression as being effective in managing the breath amplitude if respiration-induced liver motion in the cranial-caudal (CC) direction during compression was ≤5 mm and as being ineffective if >5 mm of motion was observed. Gender, age, body mass index (BMI), transarterial chemoembolization history, liver resection history, tumor area, tumor number, and tumor size (diameter) were determined. Multivariate logistic regression analysis was used to analyze influencing factors associated with a breath amplitude ≤5 mm in the CC direction. RESULTS The mean respiration-induced liver motion during abdominal compression in the left-right (LR), CC, anterior-posterior (AP), and 3-dimensional vector directions was 2.9 ± 1.2 mm, 5.3 ± 2.2 mm, 2.3 ± 1.1 mm and 6.7 ± 2.1 mm, respectively. Univariate analysis indicated that gender and BMI significantly affected abdominal compression effectiveness (both p < 0.05). Multivariate analysis confirmed these two factors as significant predictors of effective abdominal compression: gender (p = 0.030) and BMI (p = 0.006). There was a strong correlation between gender and compression effectiveness (odds ratio [OR] = 7.450) and an even stronger correlation between BMI and compression effectiveness (OR = 10.842). CONCLUSIONS The magnitude of respiration-induced liver motion of patients with intrahepatic carcinoma undergoing abdominal compression is affected by gender and BMI, with abdominal compression being less effective in men and overweight patients.
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Affiliation(s)
- Yong Hu
- Department of Radiation Oncology, Zhongshan Hospital, Fudan University, 180, Feng Lin Road, Shanghai, 200032 China
| | - Yong-Kang Zhou
- Department of Radiation Oncology, Zhongshan Hospital, Fudan University, 180, Feng Lin Road, Shanghai, 200032 China
| | - Yi-Xing Chen
- Department of Radiation Oncology, Zhongshan Hospital, Fudan University, 180, Feng Lin Road, Shanghai, 200032 China
| | - Zhao-Chong Zeng
- Department of Radiation Oncology, Zhongshan Hospital, Fudan University, 180, Feng Lin Road, Shanghai, 200032 China
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Nuyttens JJ, Moiseenko V, McLaughlin M, Jain S, Herbert S, Grimm J. Esophageal Dose Tolerance in Patients Treated With Stereotactic Body Radiation Therapy. Semin Radiat Oncol 2016; 26:120-8. [DOI: 10.1016/j.semradonc.2015.11.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Poulsen PR, Worm ES, Petersen JBB, Grau C, Fledelius W, Høyer M. Kilovoltage intrafraction motion monitoring and target dose reconstruction for stereotactic volumetric modulated arc therapy of tumors in the liver. Radiother Oncol 2014; 111:424-30. [PMID: 24997991 DOI: 10.1016/j.radonc.2014.05.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 04/30/2014] [Accepted: 05/24/2014] [Indexed: 12/21/2022]
Abstract
PURPOSE To use intrafraction kilovoltage (kV) imaging during liver stereotactic body radiotherapy (SBRT) delivered by volumetric modulated arc therapy (VMAT) to estimate the intra-treatment target motion and to reconstruct the delivered target dose. METHODS Six liver SBRT patients with 2-3 implanted gold markers received SBRT in three fractions of 18.75 Gy or 25 Gy. CTV-to-PTV margins of 5 mm in the axial plane and 10 mm in the cranio-caudal directions were applied. A VMAT plan was designed to give minimum target doses of 95% (CTV) and 67% (PTV). At each fraction, the 3D marker trajectory was estimated by fluoroscopic kV imaging throughout treatment delivery and used to reconstruct the actually delivered CTV dose. The reduction in D95 (minimum dose to 95% of the CTV) relative to the planned D95 was calculated. RESULTS The kV position estimation had mean root-mean-square errors of 0.36 mm and 0.47 mm parallel and perpendicular to the kV imager, respectively. Intrafraction motion caused a mean 3D target position error of 2.9 mm and a mean D95 reduction of 6.0%. The D95 reduction correlated with the mean 3D target position error during a fraction. CONCLUSIONS Kilovoltage imaging for detailed motion monitoring with dose reconstruction of VMAT-based liver SBRT was demonstrated for the first time showing large dosimetric impact of intrafraction tumor motion.
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Affiliation(s)
- Per Rugaard Poulsen
- Department of Oncology, Aarhus University Hospital, Denmark; Institute of Clinical Medicine, Aarhus University, Denmark.
| | - Esben S Worm
- Department of Oncology, Aarhus University Hospital, Denmark; Department of Medical Physics, Aarhus University Hospital, Denmark
| | | | - Cai Grau
- Department of Oncology, Aarhus University Hospital, Denmark; Institute of Clinical Medicine, Aarhus University, Denmark
| | - Walther Fledelius
- Department of Oncology, Aarhus University Hospital, Denmark; Department of Medical Physics, Aarhus University Hospital, Denmark
| | - Morten Høyer
- Department of Oncology, Aarhus University Hospital, Denmark; Institute of Clinical Medicine, Aarhus University, Denmark
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Abbas H, Chang B, Chen ZJ. Motion management in gastrointestinal cancers. J Gastrointest Oncol 2014; 5:223-35. [PMID: 24982771 DOI: 10.3978/j.issn.2078-6891.2014.028] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Accepted: 05/27/2014] [Indexed: 12/17/2022] Open
Abstract
The presence of tumor and organ motions complicates the planning and delivery of radiotherapy for gastrointestinal cancers. Without proper accounting of the movements, target volume could be under-dosed and the nearby normal critical organs could be over-dosed. This situation is further exacerbated by the close proximity of abdominal tumors to many normal organs at risk (OARs). A number of strategies have been developed to deal with tumor and organ motions in radiotherapy. This article presents a review of the techniques used in the evaluation, quantification, and management of tumor and organ motions for radiotherapy of gastrointestinal cancers.
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Affiliation(s)
- Hassan Abbas
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Bryan Chang
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Zhe Jay Chen
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut, USA
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Schmidhalter D, Fix MK, Wyss M, Schaer N, Munro P, Scheib S, Kunz P, Manser P. Evaluation of a new six degrees of freedom couch for radiation therapy. Med Phys 2013; 40:111710. [DOI: 10.1118/1.4823789] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Effect of dose prescription and block margin on small field treatment planning. JOURNAL OF RADIOTHERAPY IN PRACTICE 2013. [DOI: 10.1017/s1460396911000434] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractBackground and purpose: We evaluated the effect of block margin on small fields when point dose prescription (ICRU) or isodose line prescription (RTOG) formats are used.Material and methods: A total of 11 clinical SBRT cases, one 4-field prostate case and 2 phantom cases using 0, 0.5 or 1 cm block margins were analysed. Integral dose and target coverage were compared using DVHs and isodose volumes for either isodose line prescription (100% Rx dose to 95% PTV volume) or isocenter point prescription (100% Rx dose to the isocenter) were calculated.Results: Tight planning target margins using isodose line prescription leads to good target coverage but high dose heterogeneity with hot spots possibly exceeding 140% of the prescription dose for small target volumes. As block margin is increased, target coverage converges for the two methods but point dose prescriptions result in better dose homogeneity. For a given block margin, integral doses are consistently larger for isodose line prescription over point prescription, but are similar when block margins are adjusted to produce equal target coverage. As target size increases dose heterogeneity and integral dose differences disappear.Conclusions: For small targets, the ICRU point prescription method can produce comparable PTV coverage to the isodose line prescription method with less dose heterogeneity and comparable integral dose. Reduction of hot spots in potentially normal tissue and reporting clarity makes this internationally recommended prescription standard preferable.
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Hypofraction radiotherapy of liver tumor using cone beam computed tomography guidance combined with active breath control by long breath-holding. Radiother Oncol 2012; 104:379-85. [DOI: 10.1016/j.radonc.2011.11.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 11/07/2011] [Accepted: 11/22/2011] [Indexed: 12/25/2022]
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Boda-Heggemann J, Dinter D, Weiss C, Frauenfeld A, Siebenlist K, Attenberger U, Ottstadt M, Schneider F, Hofheinz RD, Wenz F, Lohr F. Hypofractionated image-guided breath-hold SABR (stereotactic ablative body radiotherapy) of liver metastases--clinical results. Radiat Oncol 2012; 7:92. [PMID: 22710033 PMCID: PMC3464721 DOI: 10.1186/1748-717x-7-92] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Accepted: 06/18/2012] [Indexed: 02/03/2023] Open
Abstract
Purpose Stereotactic Ablative Body Radiotherapy (SABR) is a non-invasive therapy option for inoperable liver oligometastases. Outcome and toxicity were retrospectively evaluated in a single-institution patient cohort who had undergone ultrasound-guided breath-hold SABR. Patients and methods 19 patients with liver metastases of various primary tumors consecutively treated with SABR (image-guidance with stereotactic ultrasound in combination with computer-controlled breath-hold) were analysed regarding overall-survival (OS), progression-free-survival (PFS), progression pattern, local control (LC), acute and late toxicity. Results PTV (planning target volume)-size was 108 ± 109cm3 (median 67.4 cm3). BED2 (Biologically effective dose in 2 Gy fraction) was 83.3 ± 26.2 Gy (median 78 Gy). Median follow-up and median OS were 12 months. Actuarial 2-year-OS-rate was 31%. Median PFS was 4 months, actuarial 1-year-PFS-rate was 20%. Site of first progression was predominantly distant. Regression of irradiated lesions was observed in 84% (median time to detection of regression was 2 months). Actuarial 6-month-LC-rate was 92%, 1- and 2-years-LC-rate 57%, respectively. BED2 influenced LC. When a cut-off of BED2 = 78 Gy was used, the higher BED2 values resulted in improved local control with a statistical trend to significance (p = 0.0999). Larger PTV-sizes, inversely correlated with applied dose, resulted in lower local control, also with a trend to significance (p-value = 0.08) when a volume cut-off of 67 cm3 was used. No local relapse was observed at PTV-sizes < 67 cm3 and BED2 > 78 Gy. No acute clinical toxicity > °2 was observed. Late toxicity was also ≤ °2 with the exception of one gastrointestinal bleeding-episode 1 year post-SABR. A statistically significant elevation in the acute phase was observed for alkaline-phosphatase; in the chronic phase for alkaline-phosphatase, bilirubine, cholinesterase and C-reactive protein. Conclusions A trend to statistically significant correlation of local progression was observed for BED2 and PTV-size. Dose-levels BED2 > 78 Gy cannot be reached in large lesions constituting a significant fraction of this series. Image-guided SABR (igSABR) is therefore an effective non-invasive treatment modality with low toxicity in patients with small inoperable liver metastases.
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Affiliation(s)
- Judit Boda-Heggemann
- Department of Radiation Oncology, University Medical Center Mannheim, University of Heidelberg, Mannheim, Germany.
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Bharat S, Parikh P, Noel C, Meltsner M, Bzdusek K, Kaus M. Motion-compensated estimation of delivered dose during external beam radiation therapy: implementation in Philips' Pinnacle(3) treatment planning system. Med Phys 2012; 39:437-43. [PMID: 22225314 DOI: 10.1118/1.3670374] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Recent research efforts investigating dose escalation techniques for three-dimensional conformal radiation therapy (3D CRT) and intensity modulated radiation therapy (IMRT) have demonstrated great benefit when high-dose hypofractionated treatment schemes are implemented. The use of these paradigms emphasizes the importance of smaller treatment margins to avoid high dose to surrounding normal tissue or organs at risk (OARs). However, tighter margins may lead to underdosage of the target due to the presence of organ motion. It is important to characterize organ motion and possibly account for it during treatment delivery. The need for real-time localization of dynamic targets has encouraged the use and development of more continuous motion monitoring systems such as kilo-voltage/fluoroscopic imaging, electromagnetic tracking, and optical monitoring systems. METHODS This paper presents the implementation of an algorithm to quantify translational and rotational interfractional and intrafractional prostate motion and compute the dosimetric effects of these motion patterns. The estimated delivered dose is compared with the static plan dose to evaluate the success of delivering the plan in the presence of prostate motion. The method is implemented on a commercial treatment planning system (Pinnacle(3), Philips Radiation Oncology Systems, Philips Healthcare) and is termed delivered dose investigational tool (DiDIT). The DiDIT implementation in Pinnacle(3) is validated by comparisons with previously published results. Finally, different workflows are discussed with respect to the potential use of this tool in clinical treatment planning. RESULTS The DiDIT dose estimation process took approximately 5-20 min (depending on the number of fractions analyzed) on a Pinnacle(3) 9.100 research version running on a Dell M90 system (Dell, Inc., Round Rock, TX, USA) equipped with an Intel Core 2 Duo processor (Intel Corporation, Santa Clara, CA, USA). The DiDIT implementation in Pinnacle(3) was found to be in agreement with previously published results, on the basis of the percent dose difference (PDD). This metric was also utilized to compare plan dose versus delivered dose, for prostate targets in three clinically acceptable treatment plans. CONCLUSIONS This paper presents results from the implementation of an algorithm on a commercially available treatment planning system that quantifies the dosimetric effects of interfractional and intrafractional motion in external beam radiation therapy (EBRT) of prostate cancer. The implementation of this algorithm within a commercial treatment planning system such as Pinnacle(3) enables easy deployment in the existing clinical workflow. The results of the PDD tests validate the implementation of the DiDIT algorithm in Pinnacle(3), in comparison with previously published results.
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Affiliation(s)
- Shyam Bharat
- Philips Medical Systems, Fitchburg, Wisconsin 53711, USA
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Law AL, Ng WT, Lee MC, Chan AT, Fung KH, Li F, Lao WC, Lee AW. Treatment of primary liver cancer using highly-conformal radiotherapy with kv-image guidance and respiratory control. Radiother Oncol 2012; 102:56-61. [DOI: 10.1016/j.radonc.2011.05.022] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 04/15/2011] [Accepted: 05/03/2011] [Indexed: 11/29/2022]
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Grimm J, LaCouture T, Croce R, Yeo I, Zhu Y, Xue J. Dose tolerance limits and dose volume histogram evaluation for stereotactic body radiotherapy. J Appl Clin Med Phys 2011; 12:3368. [PMID: 21587185 PMCID: PMC5718687 DOI: 10.1120/jacmp.v12i2.3368] [Citation(s) in RCA: 123] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Revised: 10/14/2010] [Accepted: 01/10/2011] [Indexed: 12/15/2022] Open
Abstract
Almost 20 years ago, Emami et al. presented a comprehensive set of dose tolerance limits for normal tissue organs to therapeutic radiation, which has proven essential to the field of radiation oncology. The paradigm of stereotactic body radiotherapy (SBRT) has dramatically different dosing schemes but, to date, there has still been no comprehensive set of SBRT normal organ dose tolerance limits. As an initial step toward that goal, we performed an extensive review of the literature to compare dose limits utilized and reported in existing publications. The impact on dose tolerance limits of some key aspects of the methods and materials of the various authors is discussed. We have organized a table of 500 dose tolerance limits of normal structures for SBRT. We still observed several dose limits that are unknown or not validated. Data for SBRT dose tolerance limits are still preliminary and further clinical trials and validation are required. This manuscript presents an extensive collection of normal organ dose tolerance limits to facilitate both clinical application and further research.
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Affiliation(s)
- Jimm Grimm
- Department of Radiation Oncology, Cooper University Hospital, One Cooper Plaza, Camden, NJ 08103, USA.
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Kuo HC, Liu WS, Wu A, Mah D, Chuang KS, Hong L, Yaparpalvi R, Guha C, Kalnicki S. Biological impact of geometric uncertainties: what margin is needed for intra-hepatic tumors? Radiat Oncol 2010; 5:48. [PMID: 20525298 PMCID: PMC2893459 DOI: 10.1186/1748-717x-5-48] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Accepted: 06/03/2010] [Indexed: 01/14/2023] Open
Abstract
Background To evaluate and compare the biological impact on different proposed margin recipes for the same geometric uncertainties for intra-hepatic tumors with different tumor cell types or clinical stages. Method Three different margin recipes based on tumor motion were applied to sixteen IMRT plans with a total of twenty two intra-hepatic tumors. One recipe used the full amplitude of motion measured from patients to generate margins. A second used 70% of the full amplitude of motion, while the third had no margin for motion. The biological effects of geometric uncertainty in these three situations were evaluated with Equivalent Uniform Doses (EUD) for various survival fractions at 2 Gy (SF2). Results There was no significant difference in the biological impact between the full motion margin and the 70% motion margin. Also, there was no significant difference between different tumor cell types. When the margin for motion was eliminated, the difference of the biological impact was significant among different cell types due to geometric uncertainties. Elimination of the motion margin requires dose escalation to compensate for the biological dose reduction due to the geometric misses during treatment. Conclusions Both patient-based margins of full motion and of 70% motion are sufficient to prevent serious dosimetric error. Clinical implementation of margin reduction should consider the tumor sensitivity to radiation.
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Affiliation(s)
- Hsiang-Chi Kuo
- Department of Radiation Oncology, Montefiore Medical Center, USA.
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Wunderink W, Méndez Romero A, Seppenwoolde Y, de Boer H, Levendag P, Heijmen B. Potentials and limitations of guiding liver stereotactic body radiation therapy set-up on liver-implanted fiducial markers. Int J Radiat Oncol Biol Phys 2010; 77:1573-83. [PMID: 20399034 DOI: 10.1016/j.ijrobp.2009.10.040] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Revised: 10/15/2009] [Accepted: 10/23/2009] [Indexed: 12/19/2022]
Abstract
PURPOSE We investigated the potentials and limitations of guiding liver stereotactic body radiation therapy (SBRT) set-up on liver-implanted fiducial markers. METHODS AND MATERIALS Twelve patients undergoing compression-supported SBRT in a stereotactic body frame received fluoroscopy at treatment preparation and before each treatment fraction. In fluoroscopic videos we localized the markers and diaphragm tip at expiration and the spine (measurements on free-breathing and abdominal compression). Day-to-day displacements, rotations (markers only), and deformations were determined. Marker guidance was compared to conventional set-up strategies in treatment set-up simulations. RESULTS For compression, day-to-day motion of markers with respect to their centers of mass (COM) was sigma = 0.9 mm (random error SD), Sigma = 0.4 mm (systematic error SD), and <2.1 mm (maximum). Consequently, assuming that markers were closely surrounding spherical tumors, marker COM-guided set-up would have required safety margins of approximately 2 mm. Using marker COM as the gold standard, other set-up methods (using no correction, spine registration, and diaphragm tip craniocaudal registration) resulted in set-up errors of 1.4 mm < sigma < 2.8 mm, 2.6 mm < Sigma < 5.1 mm, and 6.3 mm < max < 12.4 mm. Day-to-day intermarker motion of <16.7%, 2.2% median, and rotations between 3.5 degrees and 7.2 degrees were observed. For markers not surrounding the tumor, e.g., 5 cm between respective COMs, these changes could effect residual tumor set-up errors up to 8.4 mm, 1.1 mm median (deformations), and 3.1 mm to 6.3 mm (rotations). Compression did not systematically contribute to deformations and rotations, since similar results were observed for free-breathing. CONCLUSIONS If markers can be implanted near and around the tumor, residual set-up errors by marker guidance are small compared to those of conventional set-up methods, allowing high-precision tumor radiation set-up. However, substantial errors may result if markers are not implanted precisely, requiring further research to obtain adequate safety margins.
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Affiliation(s)
- Wouter Wunderink
- Erasmus Medical Center-Daniel den Hoed Cancer Center, Department of Radiation Oncology, Groene Hilledijk 301, 3008AE Rotterdam, The Netherlands.
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Rajagopalan MS, Heron DE. Role of PET/CT imaging in stereotactic body radiotherapy. Future Oncol 2010; 6:305-17. [DOI: 10.2217/fon.09.166] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Stereotactic body radiotherapy (SBRT) is a relatively new technique that enables delivery of high doses of radiation to malignancies throughout the body with a higher degree of precision than conventional radiation modalities. PET and computed tomography are rapidly being adopted for the evaluation of patients with cancer, and its role in conjunction with SBRT is under active investigation. This article reviews the literature regarding the utility of PET and computed tomography in treatment planning, follow-up imaging, relationship with clinical outcomes, and other topics in patients treated with SBRT. These questions are investigated for cancers of the lung, head and neck, pancreas and liver. A brief overview of various commercially available SBRT treatment systems is also included.
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Affiliation(s)
- Malolan S Rajagopalan
- BS UPMC Cancer Pavilion, University of Pittsburgh Cancer Institute, 5150 Centre Avenue, Suite No. 545, Pittsburgh, PA 15232, USA
| | - Dwight E Heron
- FACRO Department of Radiation Oncology, UPMC Cancer Pavilion, University of Pittsburgh Cancer Institute, 5150 Centre Ave, Suite No. 545, Pittsburgh, PA 15232, USA
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Jacso F, Kouznetsov A, Smith WL. Development and evaluation of an ultrasound-guided tracking and gating system for hepatic radiotherapy. Med Phys 2009; 36:5633-40. [DOI: 10.1118/1.3250893] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
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Reduction of respiratory liver tumor motion by abdominal compression in stereotactic body frame, analyzed by tracking fiducial markers implanted in liver. Int J Radiat Oncol Biol Phys 2008; 71:907-15. [PMID: 18514783 DOI: 10.1016/j.ijrobp.2008.03.010] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2007] [Revised: 03/11/2008] [Accepted: 03/12/2008] [Indexed: 12/11/2022]
Abstract
PURPOSE To investigate in a three-dimensional framework the effectiveness and reproducibility of reducing the respiratory motion of liver tumors using abdominal compression in a stereotactic body frame. METHODS AND MATERIALS A total of 12 patients with liver tumors, who were treated with stereotactic body radiotherapy, were included in this study. These patients had three gold fiducial markers implanted in the healthy liver tissue surrounding the tumor. Fluoroscopic videos were acquired on the planning day and before each treatment fraction to visualize the motion of the fiducial markers during free breathing and varying levels of abdominal compression. Software was developed to track the fiducial markers and measure their excursions. RESULTS Abdominal compression reduced the patient group median excursion by 62% in the craniocaudal and 38% in the anteroposterior direction with respect to the median free-breathing excursions. In the left-right direction, the median excursion increased 15% (maximal increase 1.6 mm). The median residual excursion was 4.1 mm in the craniocaudal, 2.4 mm in the anteroposterior, and 1.8 mm in the left-right direction. The mean excursions were reduced by compression to <5 mm in all patients and all directions, with two exceptions (craniocaudal excursion reduction of 20.5 mm to 7.4 mm and of 21.1 mm to 5.9 mm). The residual excursions reproduced well during the treatment course, and the craniocaudal excursions measured on the treatment days were never significantly (alpha = 0.05) greater than on the planning days. Fine tuning the compression did not considerably change the excursion on the treatment days. CONCLUSIONS Abdominal compression effectively reduced liver tumor motion, yielding small and reproducible excursions in three dimensions. The compression level established at planning could have been safely used on the treatment days.
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