Image-guided radiation therapy: physician's perspectives

International Nuclear Information System (INIS)

Gupta, T.; Anand Narayan, C.

2012-01-01

The evolution of radiotherapy has been ontogenetically linked to medical imaging. Over the years, major technological innovations have resulted in substantial improvements in radiotherapy planning, delivery, and verification. The increasing use of computed tomography imaging for target volume delineation coupled with availability of computer-controlled treatment planning and delivery systems have progressively led to conformation of radiation dose to the target tissues while sparing surrounding normal tissues. Recent advances in imaging technology coupled with improved treatment delivery allow near-simultaneous soft-tissue localization of tumor and repositioning of patient. The integration of various imaging modalities within the treatment room for guiding radiation delivery has vastly improved the management of geometric uncertainties in contemporary radiotherapy practice ushering in the paradigm of image-guided radiation therapy (IGRT). Image-guidance should be considered a necessary and natural corollary to high-precision radiotherapy that was long overdue. Image-guided radiation therapy not only provides accurate information on patient and tumor position on a quantitative scale, it also gives an opportunity to verify consistency of planned and actual treatment geometry including adaptation to daily variations resulting in improved dose delivery. The two main concerns with IGRT are resource-intensive nature of delivery and increasing dose from additional imaging. However, increasing the precision and accuracy of radiation delivery through IGRT is likely to reduce toxicity with potential for dose escalation and improved tumor control resulting in favourable therapeutic index. The radiation oncology community needs to leverage this technology to generate high-quality evidence to support widespread adoption of IGRT in contemporary radiotherapy practice. (author)

Adaptive Motion Compensation in Radiotherapy

CERN Document Server

Murphy, Martin J

2011-01-01

External-beam radiotherapy has long been challenged by the simple fact that patients can (and do) move during the delivery of radiation. Recent advances in imaging and beam delivery technologies have made the solution--adapting delivery to natural movement--a practical reality. Adaptive Motion Compensation in Radiotherapy provides the first detailed treatment of online interventional techniques for motion compensation radiotherapy. This authoritative book discusses: Each of the contributing elements of a motion-adaptive system, including target detection and tracking, beam adaptation, and pati

Automated replication of cone beam CT-guided treatments in the Pinnacle(3) treatment planning system for adaptive radiotherapy.

Science.gov (United States)

Hargrave, Catriona; Mason, Nicole; Guidi, Robyn; Miller, Julie-Anne; Becker, Jillian; Moores, Matthew; Mengersen, Kerrie; Poulsen, Michael; Harden, Fiona

2016-03-01

Time-consuming manual methods have been required to register cone-beam computed tomography (CBCT) images with plans in the Pinnacle(3) treatment planning system in order to replicate delivered treatments for adaptive radiotherapy. These methods rely on fiducial marker (FM) placement during CBCT acquisition or the image mid-point to localise the image isocentre. A quality assurance study was conducted to validate an automated CBCT-plan registration method utilising the Digital Imaging and Communications in Medicine (DICOM) Structure Set (RS) and Spatial Registration (RE) files created during online image-guided radiotherapy (IGRT). CBCTs of a phantom were acquired with FMs and predetermined setup errors using various online IGRT workflows. The CBCTs, DICOM RS and RE files were imported into Pinnacle(3) plans of the phantom and the resulting automated CBCT-plan registrations were compared to existing manual methods. A clinical protocol for the automated method was subsequently developed and tested retrospectively using CBCTs and plans for six bladder patients. The automated CBCT-plan registration method was successfully applied to thirty-four phantom CBCT images acquired with an online 0 mm action level workflow. Ten CBCTs acquired with other IGRT workflows required manual workarounds. This was addressed during the development and testing of the clinical protocol using twenty-eight patient CBCTs. The automated CBCT-plan registrations were instantaneous, replicating delivered treatments in Pinnacle(3) with errors of ±0.5 mm. These errors were comparable to mid-point-dependant manual registrations but superior to FM-dependant manual registrations. The automated CBCT-plan registration method quickly and reliably replicates delivered treatments in Pinnacle(3) for adaptive radiotherapy.

Adaptive Radiotherapy Planning on Decreasing Gross Tumor Volumes as Seen on Megavoltage Computed Tomography Images

International Nuclear Information System (INIS)

Woodford, Curtis; Yartsev, Slav; Dar, A. Rashid; Bauman, Glenn; Van Dyk, Jake

2007-01-01

Purpose: To evaluate gross tumor volume (GTV) changes for patients with non-small-cell lung cancer by using daily megavoltage (MV) computed tomography (CT) studies acquired before each treatment fraction on helical tomotherapy and to relate the potential benefit of adaptive image-guided radiotherapy to changes in GTV. Methods and Materials: Seventeen patients were prescribed 30 fractions of radiotherapy on helical tomotherapy for non-small-cell lung cancer at London Regional Cancer Program from Dec 2005 to March 2007. The GTV was contoured on the daily MVCT studies of each patient. Adapted plans were created using merged MVCT-kilovoltage CT image sets to investigate the advantages of replanning for patients with differing GTV regression characteristics. Results: Average GTV change observed over 30 fractions was -38%, ranging from -12 to -87%. No significant correlation was observed between GTV change and patient's physical or tumor features. Patterns of GTV changes in the 17 patients could be divided broadly into three groups with distinctive potential for benefit from adaptive planning. Conclusions: Changes in GTV are difficult to predict quantitatively based on patient or tumor characteristics. If changes occur, there are points in time during the treatment course when it may be appropriate to adapt the plan to improve sparing of normal tissues. If GTV decreases by greater than 30% at any point in the first 20 fractions of treatment, adaptive planning is appropriate to further improve the therapeutic ratio

TH-CD-202-11: Implications for Online Adaptive and Non-Adaptive Radiotherapy of Gastic and Gastroesophageal Junction Cancers Using MRI-Guided Radiotherapy

International Nuclear Information System (INIS)

Mittauer, K; Geurts, M; Toya, R; Bassetti, M; Harari, P; Paliwal, B; Bayouth, J

2016-01-01

Purpose: Radiotherapy for gastric and gastroesophageal junction (GEJ) tumors commonly requires large margins due to deformation, motion and variable changes of the stomach anatomy, at the risk of increased normal tissue toxicities. This work quantifies the interfraction variation of stomach deformation from daily MRI-guided radiotherapy to allow for a more targeted determination of margin expansion in the treatment of gastric and GEJ tumors. Methods: Five patients treated for gastric (n=3) and gastroesophageal junction (n=2) cancers with conventionally fractionated radiotherapy underwent daily MR imaging on a clinical MR-IGRT system. Treatment planning and contours were performed based on the MR simulation. The stomach was re-contoured on each daily volumetric setup MR. Dice similarity coefficients (DSC) of the daily stomach were computed to evaluate the stomach interfraction deformation. To evaluate the stomach margin, the maximum Hausdorff distance (HD) between the initial and fractional stomach surface was measured for each fraction. The margin expansion, needed to encompass all fractions, was evaluated from the union of all fractional stomachs. Results: In total, 94 fractions with daily stomach contours were evaluated. For the interfraction stomach differences, the average DSC was 0.67±0.1 for gastric and 0.62±0.1 for GEJ cases. The maximum HD of each fraction was 3.5±2.0cm (n=94) with mean HD of 0.8±0.4cm (across all surface voxels for all fractions). The margin expansion required to encompass all individual fractions (averaged across 5 patients) was 1.4 cm(superior), 2.3 cm(inferior), 2.5 cm(right), 3.2 cm(left), 3.7 cm(anterior), 3.4 cm(posterior). Maximum observed difference for margin expansion was 8.7cm(posterior) among one patient. Conclusion: We observed a notable interfractional change in daily stomach shape (i.e., mean DSC of 0.67, p<0.0001) in both gastric and GEJ patients, for which adaptive radiotherapy is indicated. A minimum PTV margin of 3

TH-CD-202-11: Implications for Online Adaptive and Non-Adaptive Radiotherapy of Gastic and Gastroesophageal Junction Cancers Using MRI-Guided Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Mittauer, K; Geurts, M; Toya, R; Bassetti, M; Harari, P; Paliwal, B; Bayouth, J [University of Wisconsin, Madison, WI (United States)

2016-06-15

Purpose: Radiotherapy for gastric and gastroesophageal junction (GEJ) tumors commonly requires large margins due to deformation, motion and variable changes of the stomach anatomy, at the risk of increased normal tissue toxicities. This work quantifies the interfraction variation of stomach deformation from daily MRI-guided radiotherapy to allow for a more targeted determination of margin expansion in the treatment of gastric and GEJ tumors. Methods: Five patients treated for gastric (n=3) and gastroesophageal junction (n=2) cancers with conventionally fractionated radiotherapy underwent daily MR imaging on a clinical MR-IGRT system. Treatment planning and contours were performed based on the MR simulation. The stomach was re-contoured on each daily volumetric setup MR. Dice similarity coefficients (DSC) of the daily stomach were computed to evaluate the stomach interfraction deformation. To evaluate the stomach margin, the maximum Hausdorff distance (HD) between the initial and fractional stomach surface was measured for each fraction. The margin expansion, needed to encompass all fractions, was evaluated from the union of all fractional stomachs. Results: In total, 94 fractions with daily stomach contours were evaluated. For the interfraction stomach differences, the average DSC was 0.67±0.1 for gastric and 0.62±0.1 for GEJ cases. The maximum HD of each fraction was 3.5±2.0cm (n=94) with mean HD of 0.8±0.4cm (across all surface voxels for all fractions). The margin expansion required to encompass all individual fractions (averaged across 5 patients) was 1.4 cm(superior), 2.3 cm(inferior), 2.5 cm(right), 3.2 cm(left), 3.7 cm(anterior), 3.4 cm(posterior). Maximum observed difference for margin expansion was 8.7cm(posterior) among one patient. Conclusion: We observed a notable interfractional change in daily stomach shape (i.e., mean DSC of 0.67, p<0.0001) in both gastric and GEJ patients, for which adaptive radiotherapy is indicated. A minimum PTV margin of 3

Imaging and concomitant dose in radiotherapy

International Nuclear Information System (INIS)

Negi, P.S.

2008-01-01

Image guidance in radiotherapy now involves multiple imaging procedures for planning, simulation, set-up inter and intrafraction monitoring. Presently ALARA (i.e. as low as reasonable achievable) is the principle of management of dose to radiation workers and patients in any diagnostic imaging procedures including image guided surgery. The situation is different in repeated radiographic/fluoroscopic imaging performed for simulation, dose planning, patient positioning and set-up corrections during preparation/execution of Image guided radiotherapy (IGRT) as well as for Intensity Modulated Radiotherapy (IMRT). Reported imaging and concomitant doses will be highlighted and discussed for the management and optimization of imaging techniques in IMRT and IGRT

Feasibility study of image guided radiotherapy for lung tumor using online and offline cone-beam CT setup verification

International Nuclear Information System (INIS)

Li Hongsheng; Li Baosheng; Lu Jie; Yin Yong; Yu Ningsha; Chen Yiru

2009-01-01

Objective: To investigate the feasibility of online and offline cone-beam CT(CBCT) guided radiotherapy for lung cancer. Methods: Fourteen patients with lung tumor treated by three-dimensional conformal radiotherapy were investigated. Online kV CBCT scan, image registration and setup correction were performed before and immediately after radiotherapy. CBCT online-guided correction data were used to calculate the population-based CTV-PTV margins under the condition of non-correction and correction in every fraction respectively. The numbers of initial images and the population-based CTV-PTV margins after the offline compensation of the system setup error were evaluated with the permission of 0.5 mm and 1.5 mm maximal residue error, respectively. Results: Under the condition of non-correction, the required margins for total error were 5.7 mm, 8.0 mm and 7.8 mm in the left-right (x axis), cranio-caudal (y axis) and anterior-posterior(z axis) directions, respectively. When the tumor was corrected in every fraction, the required margins for intra-fraction error were 2.4 mm, 2.4 mm and 2.3 mm in x,y and z axes, respectively. To correct the systematic setup error, 9 sets of CBCT images for 3.3 mm, 3.7 mm and 3.6 mm PTV margins, and 7 sets of CBCT images for 3.9 mm, 4.3 mm and 4.3 mm PTV margins in x,y and z axes were necessary when 0.5 mm and 1.5 mm maximal residue error were permitted respectively. Conclusions: Both of the online CBCT correction and the offline adaptive correction can markedly reduce the impact of setup error and reduce the required PTV margins accordingly. It is feasible to deliver the online and offline image guided radiation for patients with lung tumor. (authors)

First Clinical Release of an Online, Adaptive, Aperture-Based Image-Guided Radiotherapy Strategy in Intensity-Modulated Radiotherapy to Correct for Inter- and Intrafractional Rotations of the Prostate

International Nuclear Information System (INIS)

Deutschmann, Heinz; Kametriser, Gerhard; Steininger, Philipp; Scherer, Philipp; Schöller, Helmut; Gaisberger, Christoph; Mooslechner, Michaela; Mitterlechner, Bernhard; Weichenberger, Harald; Fastner, Gert; Wurstbauer, Karl; Jeschke, Stephan; Forstner, Rosemarie; Sedlmayer, Felix

2012-01-01

Purpose: We developed and evaluated a correction strategy for prostate rotations using direct adaptation of segments in intensity-modulated radiotherapy (IMRT). Method and Materials: Implanted fiducials (four gold markers) were used to determine interfractional translations, rotations, and dilations of the prostate. We used hybrid imaging: The markers were automatically detected in two pretreatment planar X-ray projections; their actual position in three-dimensional space was reconstructed from these images at first. The structure set comprising prostate, seminal vesicles, and adjacent rectum wall was transformed accordingly in 6 degrees of freedom. Shapes of IMRT segments were geometrically adapted in a class solution forward-planning approach, derived within seconds on-site and treated immediately. Intrafractional movements were followed in MV electronic portal images captured on the fly. Results: In 31 of 39 patients, for 833 of 1013 fractions (supine, flat couch, knee support, comfortably full bladder, empty rectum, no intraprostatic marker migrations >2 mm of more than one marker), the online aperture adaptation allowed safe reduction of margins clinical target volume–planning target volume (prostate) down to 5 mm when only interfractional corrections were applied: Dominant L-R rotations were found to be 5.3° (mean of means), standard deviation of means ±4.9°, maximum at 30.7°. Three-dimensional vector translations relative to skin markings were 9.3 ± 4.4 mm (maximum, 23.6 mm). Intrafractional movements in 7.7 ± 1.5 min (maximum, 15.1 min) between kV imaging and last beam’s electronic portal images showed further L-R rotations of 2.5° ± 2.3° (maximum, 26.9°), and three-dimensional vector translations of 3.0 ±3.7 mm (maximum, 10.2 mm). Addressing intrafractional errors could further reduce margins to 3 mm. Conclusion: We demonstrated the clinical feasibility of an online adaptive image-guided, intensity-modulated prostate protocol on a standard

First clinical release of an online, adaptive, aperture-based image-guided radiotherapy strategy in intensity-modulated radiotherapy to correct for inter- and intrafractional rotations of the prostate.

Science.gov (United States)

Deutschmann, Heinz; Kametriser, Gerhard; Steininger, Philipp; Scherer, Philipp; Schöller, Helmut; Gaisberger, Christoph; Mooslechner, Michaela; Mitterlechner, Bernhard; Weichenberger, Harald; Fastner, Gert; Wurstbauer, Karl; Jeschke, Stephan; Forstner, Rosemarie; Sedlmayer, Felix

2012-08-01

We developed and evaluated a correction strategy for prostate rotations using direct adaptation of segments in intensity-modulated radiotherapy (IMRT). Implanted fiducials (four gold markers) were used to determine interfractional translations, rotations, and dilations of the prostate. We used hybrid imaging: The markers were automatically detected in two pretreatment planar X-ray projections; their actual position in three-dimensional space was reconstructed from these images at first. The structure set comprising prostate, seminal vesicles, and adjacent rectum wall was transformed accordingly in 6 degrees of freedom. Shapes of IMRT segments were geometrically adapted in a class solution forward-planning approach, derived within seconds on-site and treated immediately. Intrafractional movements were followed in MV electronic portal images captured on the fly. In 31 of 39 patients, for 833 of 1013 fractions (supine, flat couch, knee support, comfortably full bladder, empty rectum, no intraprostatic marker migrations >2 mm of more than one marker), the online aperture adaptation allowed safe reduction of margins clinical target volume-planning target volume (prostate) down to 5 mm when only interfractional corrections were applied: Dominant L-R rotations were found to be 5.3° (mean of means), standard deviation of means ±4.9°, maximum at 30.7°. Three-dimensional vector translations relative to skin markings were 9.3 ± 4.4 mm (maximum, 23.6 mm). Intrafractional movements in 7.7 ± 1.5 min (maximum, 15.1 min) between kV imaging and last beam's electronic portal images showed further L-R rotations of 2.5° ± 2.3° (maximum, 26.9°), and three-dimensional vector translations of 3.0 ±3.7 mm (maximum, 10.2 mm). Addressing intrafractional errors could further reduce margins to 3 mm. We demonstrated the clinical feasibility of an online adaptive image-guided, intensity-modulated prostate protocol on a standard linear accelerator to correct 6 degrees of freedom of

Deep architecture neural network-based real-time image processing for image-guided radiotherapy.

Science.gov (United States)

Mori, Shinichiro

2017-08-01

To develop real-time image processing for image-guided radiotherapy, we evaluated several neural network models for use with different imaging modalities, including X-ray fluoroscopic image denoising. Setup images of prostate cancer patients were acquired with two oblique X-ray fluoroscopic units. Two types of residual network were designed: a convolutional autoencoder (rCAE) and a convolutional neural network (rCNN). We changed the convolutional kernel size and number of convolutional layers for both networks, and the number of pooling and upsampling layers for rCAE. The ground-truth image was applied to the contrast-limited adaptive histogram equalization (CLAHE) method of image processing. Network models were trained to keep the quality of the output image close to that of the ground-truth image from the input image without image processing. For image denoising evaluation, noisy input images were used for the training. More than 6 convolutional layers with convolutional kernels >5×5 improved image quality. However, this did not allow real-time imaging. After applying a pair of pooling and upsampling layers to both networks, rCAEs with >3 convolutions each and rCNNs with >12 convolutions with a pair of pooling and upsampling layers achieved real-time processing at 30 frames per second (fps) with acceptable image quality. Use of our suggested network achieved real-time image processing for contrast enhancement and image denoising by the use of a conventional modern personal computer. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Image-guided radiotherapy in near real time with intensity-modulated radiotherapy megavoltage treatment beam imaging.

Science.gov (United States)

Mao, Weihua; Hsu, Annie; Riaz, Nadeem; Lee, Louis; Wiersma, Rodney; Luxton, Gary; King, Christopher; Xing, Lei; Solberg, Timothy

2009-10-01

To utilize image-guided radiotherapy (IGRT) in near real time by obtaining and evaluating the online positions of implanted fiducials from continuous electronic portal imaging device (EPID) imaging of prostate intensity-modulated radiotherapy (IMRT) delivery. Upon initial setup using two orthogonal images, the three-dimensional (3D) positions of all implanted fiducial markers are obtained, and their expected two-dimensional (2D) locations in the beam's-eye-view (BEV) projection are calculated for each treatment field. During IMRT beam delivery, EPID images of the megavoltage treatment beam are acquired in cine mode and subsequently analyzed to locate 2D locations of fiducials in the BEV. Simultaneously, 3D positions are estimated according to the current EPID image, information from the setup portal images, and images acquired at other gantry angles (the completed treatment fields). The measured 2D and 3D positions of each fiducial are compared with their expected 2D and 3D setup positions, respectively. Any displacements larger than a predefined tolerance may cause the treatment system to suspend the beam delivery and direct the therapists to reposition the patient. Phantom studies indicate that the accuracy of 2D BEV and 3D tracking are better than 1 mm and 1.4 mm, respectively. A total of 7330 images from prostate treatments were acquired and analyzed, showing a maximum 2D displacement of 6.7 mm and a maximum 3D displacement of 6.9 mm over 34 fractions. This EPID-based, real-time IGRT method can be implemented on any external beam machine with portal imaging capabilities without purchasing any additional equipment, and there is no extra dose delivered to the patient.

TU-AB-BRA-12: Quality Assurance of An Integrated Magnetic Resonance Image Guided Adaptive Radiotherapy Machine Using Cherenkov Imaging

Energy Technology Data Exchange (ETDEWEB)

Andreozzi, J; Bruza, P; Saunders, S; Pogue, B [Dartmouth College, Hanover, NH (United States); Mooney, K; Curcuru, A; Green, O [Washington University School of Medicine, Saint Louis, MO (United States); Gladstone, D [Dartmouth-Hitchcock Med. Ctr., Lebanon, NH (Lebanon)

2016-06-15

Purpose: To investigate the viability of using Cherenkov imaging as a fast and robust method for quality assurance tests in the presence of a magnetic field, where other instruments can be limited. Methods: Water tank measurements were acquired from a clinically utilized adaptive magnetic resonance image guided radiation therapy (MR-IGRT) machine with three multileaf-collimator equipped 60Co sources. Cherenkov imaging used an intensified charge coupled device (ICCD) camera placed 3.5m from the treatment isocenter, looking down the bore of the 0.35T MRI into a water tank. Images were post-processed to make quantitative comparison between Cherenkov light intensity with both film and treatment planning system predictions, in terms of percent depth dose curves as well as lateral beam profile measurements. A TG-119 commissioning test plan (C4: C-Shape) was imaged in real-time at 6.33 frames per second to investigate the temporal and spatial resolution of the Cherenkov imaging technique. Results: A .33mm/pixel Cherenkov image resolution was achieved across 1024×1024 pixels in this setup. Analysis of the Cherenkov image of a 10.5×10.5cm treatment beam in the water tank successfully measured the beam width at the depth of maximum dose within 1.2% of the film measurement at the same point. The percent depth dose curve for the same beam was on average within 2% of ionization chamber measurements for corresponding depths between 3–100mm. Cherenkov video of the TG-119 test plan provided qualitative agreement with the treatment planning system dose predictions, and a novel temporal verification of the treatment. Conclusions: Cherenkov imaging was successfully used to make QA measurements of percent depth dose curves and cross beam profiles of MRI-IGRT radiotherapy machines after only several seconds of beam-on time and data capture; both curves were extracted from the same data set. Video-rate imaging of a dynamic treatment plan provided new information regarding temporal

WE-EF-BRD-01: Past, Present and Future: MRI-Guided Radiotherapy From 2005 to 2025

Energy Technology Data Exchange (ETDEWEB)

Lagendijk, J. [University Medical Center Utrecht (Netherlands)

2015-06-15

MRI-guided treatment is a growing area of medicine, particularly in radiotherapy and surgery. The exquisite soft tissue anatomic contrast offered by MRI, along with functional imaging, makes the use of MRI during therapeutic procedures very attractive. Challenging the utility of MRI in the therapy room are many issues including the physics of MRI and the impact on the environment and therapeutic instruments, the impact of the room and instruments on the MRI; safety, space, design and cost. In this session, the applications and challenges of MRI-guided treatment will be described. The session format is: Past, present and future: MRI-guided radiotherapy from 2005 to 2025: Jan Lagendijk Battling Maxwell’s equations: Physics challenges and solutions for hybrid MRI systems: Paul Keall I want it now!: Advances in MRI acquisition, reconstruction and the use of priors to enable fast anatomic and physiologic imaging to inform guidance and adaptation decisions: Yanle Hu MR in the OR: The growth and applications of MRI for interventional radiology and surgery: Rebecca Fahrig Learning Objectives: To understand the history and trajectory of MRI-guided radiotherapy To understand the challenges of integrating MR imaging systems with linear accelerators To understand the latest in fast MRI methods to enable the visualisation of anatomy and physiology on radiotherapy treatment timescales To understand the growing role and challenges of MRI for image-guided surgical procedures My disclosures are publicly available and updated at: http://sydney.edu.au/medicine/radiation-physics/about-us/disclosures.php.

Image-Guided Radiotherapy in Near Real Time With Intensity-Modulated Radiotherapy Megavoltage Treatment Beam Imaging

International Nuclear Information System (INIS)

Mao Weihua; Hsu, Annie; Riaz, Nadeem; Lee, Louis; Wiersma, Rodney; Luxton, Gary; King, Christopher; Xing Lei; Solberg, Timothy

2009-01-01

Purpose: To utilize image-guided radiotherapy (IGRT) in near real time by obtaining and evaluating the online positions of implanted fiducials from continuous electronic portal imaging device (EPID) imaging of prostate intensity-modulated radiotherapy (IMRT) delivery. Methods and Materials: Upon initial setup using two orthogonal images, the three-dimensional (3D) positions of all implanted fiducial markers are obtained, and their expected two-dimensional (2D) locations in the beam's-eye-view (BEV) projection are calculated for each treatment field. During IMRT beam delivery, EPID images of the megavoltage treatment beam are acquired in cine mode and subsequently analyzed to locate 2D locations of fiducials in the BEV. Simultaneously, 3D positions are estimated according to the current EPID image, information from the setup portal images, and images acquired at other gantry angles (the completed treatment fields). The measured 2D and 3D positions of each fiducial are compared with their expected 2D and 3D setup positions, respectively. Any displacements larger than a predefined tolerance may cause the treatment system to suspend the beam delivery and direct the therapists to reposition the patient. Results: Phantom studies indicate that the accuracy of 2D BEV and 3D tracking are better than 1 mm and 1.4 mm, respectively. A total of 7330 images from prostate treatments were acquired and analyzed, showing a maximum 2D displacement of 6.7 mm and a maximum 3D displacement of 6.9 mm over 34 fractions. Conclusions: This EPID-based, real-time IGRT method can be implemented on any external beam machine with portal imaging capabilities without purchasing any additional equipment, and there is no extra dose delivered to the patient.

Intra-patient semi-automated segmentation of the cervix-uterus in CT-images for adaptive radiotherapy of cervical cancer

Science.gov (United States)

Luiza Bondar, M.; Hoogeman, Mischa; Schillemans, Wilco; Heijmen, Ben

2013-08-01

For online adaptive radiotherapy of cervical cancer, fast and accurate image segmentation is required to facilitate daily treatment adaptation. Our aim was twofold: (1) to test and compare three intra-patient automated segmentation methods for the cervix-uterus structure in CT-images and (2) to improve the segmentation accuracy by including prior knowledge on the daily bladder volume or on the daily coordinates of implanted fiducial markers. The tested methods were: shape deformation (SD) and atlas-based segmentation (ABAS) using two non-rigid registration methods: demons and a hierarchical algorithm. Tests on 102 CT-scans of 13 patients demonstrated that the segmentation accuracy significantly increased by including the bladder volume predicted with a simple 1D model based on a manually defined bladder top. Moreover, manually identified implanted fiducial markers significantly improved the accuracy of the SD method. For patients with large cervix-uterus volume regression, the use of CT-data acquired toward the end of the treatment was required to improve segmentation accuracy. Including prior knowledge, the segmentation results of SD (Dice similarity coefficient 85 ± 6%, error margin 2.2 ± 2.3 mm, average time around 1 min) and of ABAS using hierarchical non-rigid registration (Dice 82 ± 10%, error margin 3.1 ± 2.3 mm, average time around 30 s) support their use for image guided online adaptive radiotherapy of cervical cancer.

The evaluation of composite dose using deformable image registration in adaptive radiotherapy for head and neck cancer

International Nuclear Information System (INIS)

Hwang, Chul Hwan; Ko, Seong Jin; Kim, Chang Soo; Kim, Jung Hoon; Kim, Dong Hyun; Choi, Seok Yoon; Ye, Soo Young; Kang, Se Sik

2013-01-01

In adaptive radiotherapy(ART), generated composite dose of surrounding normal tissue on overall treatment course which is using deformable image registration from multistage images. Also, compared with doses summed by each treatment plan and clinical significance is considered. From the first of May, 2011 to the last of July, 2012. Patients who were given treatment and had the head and neck cancer with 3-dimension conformal radiotherapy or intensity modulated radiotherapy, those who were carried out adaptive radiotherapy cause of tumor shrinkage and weight loss. Generated composite dose of surrounding normal tissue using deformable image registration was been possible, statistically significant difference was showed to mandible(48.95±3.89 vs 49.10±3.55 Gy), oral cavity(36.93±4.03 vs 38.97±5.08 Gy), parotid gland(35.71±6.22 vs 36.12±6.70 Gy) and temporomandibular joint(18.41±9.60 vs 20.13±10.42 Gy) compared with doses summed by each treatment plan. The results of this study show significant difference between composite dose by deformable image registration and doses summed by each treatment plan, composite dose by deformable image registration may generate more exact evaluation to surrounding normal tissue in adaptive radiotherapy

The evaluation of composite dose using deformable image registration in adaptive radiotherapy for head and neck cancer

Energy Technology Data Exchange (ETDEWEB)

Hwang, Chul Hwan; Ko, Seong Jin; Kim, Chang Soo; Kim, Jung Hoon; Kim, Dong Hyun; Choi, Seok Yoon; Ye, Soo Young; Kang, Se Sik [Dept. of Radiological Science, College of Health Sciences, Catholic University of Pusan, Pusan (Korea, Republic of)

2013-09-15

In adaptive radiotherapy(ART), generated composite dose of surrounding normal tissue on overall treatment course which is using deformable image registration from multistage images. Also, compared with doses summed by each treatment plan and clinical significance is considered. From the first of May, 2011 to the last of July, 2012. Patients who were given treatment and had the head and neck cancer with 3-dimension conformal radiotherapy or intensity modulated radiotherapy, those who were carried out adaptive radiotherapy cause of tumor shrinkage and weight loss. Generated composite dose of surrounding normal tissue using deformable image registration was been possible, statistically significant difference was showed to mandible(48.95±3.89 vs 49.10±3.55 Gy), oral cavity(36.93±4.03 vs 38.97±5.08 Gy), parotid gland(35.71±6.22 vs 36.12±6.70 Gy) and temporomandibular joint(18.41±9.60 vs 20.13±10.42 Gy) compared with doses summed by each treatment plan. The results of this study show significant difference between composite dose by deformable image registration and doses summed by each treatment plan, composite dose by deformable image registration may generate more exact evaluation to surrounding normal tissue in adaptive radiotherapy.

Dosimetric Advantages of Four-Dimensional Adaptive Image-Guided Radiotherapy for Lung Tumors Using Online Cone-Beam Computed Tomography

International Nuclear Information System (INIS)

Harsolia, Asif; Hugo, Geoffrey D.; Kestin, Larry L.; Grills, Inga S.; Yan Di

2008-01-01

Purpose: This study compares multiple planning techniques designed to improve accuracy while allowing reduced planning target volume (PTV) margins though image-guided radiotherapy (IGRT) with four-dimensional (4D) cone-beam computed tomography (CBCT). Methods and Materials: Free-breathing planning and 4D-CBCT scans were obtained in 8 patients with lung tumors. Four plans were generated for each patient: 3D-conformal, 4D-union, 4D-offline adaptive with a single correction (offline ART), and 4D-online adaptive with daily correction (online ART). For the 4D-union plan, the union of gross tumor volumes from all phases of the 4D-CBCT was created with a 5-mm expansion applied for setup uncertainty. For offline and online ART, the gross tumor volume was delineated at the mean position of tumor motion from the 4D-CBCT. The PTV margins were calculated from the random components of tumor motion and setup uncertainty. Results: Adaptive IGRT techniques provided better PTV coverage with less irradiated normal tissues. Compared with 3D plans, mean relative decreases in PTV volumes were 15%, 39%, and 44% using 4D-union, offline ART, and online ART planning techniques, respectively. This resulted in mean lung volume receiving ≥ 20Gy (V20) relative decreases of 21%, 23%, and 31% and mean lung dose relative decreases of 16%, 26%, and 31% for the 4D-union, 4D-offline ART, and 4D-online ART, respectively. Conclusions: Adaptive IGRT using CBCT is feasible for the treatment of patients with lung tumors and significantly decreases PTV volume and dose to normal tissues, allowing for the possibility of dose escalation. All analyzed 4D planning strategies resulted in improvements over 3D plans, with 4D-online ART appearing optimal

Dual source and dual detector arrays tetrahedron beam computed tomography for image guided radiotherapy

Science.gov (United States)

Kim, Joshua; Lu, Weiguo; Zhang, Tiezhi

2014-02-01

Cone-beam computed tomography (CBCT) is an important online imaging modality for image guided radiotherapy. But suboptimal image quality and the lack of a real-time stereoscopic imaging function limit its implementation in advanced treatment techniques, such as online adaptive and 4D radiotherapy. Tetrahedron beam computed tomography (TBCT) is a novel online imaging modality designed to improve on the image quality provided by CBCT. TBCT geometry is flexible, and multiple detector and source arrays can be used for different applications. In this paper, we describe a novel dual source-dual detector TBCT system that is specially designed for LINAC radiation treatment machines. The imaging system is positioned in-line with the MV beam and is composed of two linear array x-ray sources mounted aside the electrical portal imaging device and two linear arrays of x-ray detectors mounted below the machine head. The detector and x-ray source arrays are orthogonal to each other, and each pair of source and detector arrays forms a tetrahedral volume. Four planer images can be obtained from different view angles at each gantry position at a frame rate as high as 20 frames per second. The overlapped regions provide a stereoscopic field of view of approximately 10-15 cm. With a half gantry rotation, a volumetric CT image can be reconstructed having a 45 cm field of view. Due to the scatter rejecting design of the TBCT geometry, the system can potentially produce high quality 2D and 3D images with less radiation exposure. The design of the dual source-dual detector system is described, and preliminary results of studies performed on numerical phantoms and simulated patient data are presented.

Improvement in toxicity in high risk prostate cancer patients treated with image-guided intensity-modulated radiotherapy compared to 3D conformal radiotherapy without daily image guidance.

Science.gov (United States)

Sveistrup, Joen; af Rosenschöld, Per Munck; Deasy, Joseph O; Oh, Jung Hun; Pommer, Tobias; Petersen, Peter Meidahl; Engelholm, Svend Aage

2014-02-04

Image-guided radiotherapy (IGRT) facilitates the delivery of a very precise radiation dose. In this study we compare the toxicity and biochemical progression-free survival between patients treated with daily image-guided intensity-modulated radiotherapy (IG-IMRT) and 3D conformal radiotherapy (3DCRT) without daily image guidance for high risk prostate cancer (PCa). A total of 503 high risk PCa patients treated with radiotherapy (RT) and endocrine treatment between 2000 and 2010 were retrospectively reviewed. 115 patients were treated with 3DCRT, and 388 patients were treated with IG-IMRT. 3DCRT patients were treated to 76 Gy and without daily image guidance and with 1-2 cm PTV margins. IG-IMRT patients were treated to 78 Gy based on daily image guidance of fiducial markers, and the PTV margins were 5-7 mm. Furthermore, the dose-volume constraints to both the rectum and bladder were changed with the introduction of IG-IMRT. The 2-year actuarial likelihood of developing grade > = 2 GI toxicity following RT was 57.3% in 3DCRT patients and 5.8% in IG-IMRT patients (p analysis, 3DCRT was associated with a significantly increased risk of developing grade > = 2 GI toxicity compared to IG-IMRT (p analysis there was no difference in biochemical progression-free survival between 3DCRT and IG-IMRT. The difference in toxicity can be attributed to the combination of the IMRT technique with reduced dose to organs-at-risk, daily image guidance and margin reduction.

Developing Quality Assurance Processes for Image-Guided Adaptive Radiation Therapy

International Nuclear Information System (INIS)

Yan Di

2008-01-01

Quality assurance has long been implemented in radiation treatment as systematic actions necessary to provide adequate confidence that the radiation oncology service will satisfy the given requirements for quality care. The existing reports from the American Association of Physicists in Medicine Task Groups 40 and 53 have provided highly detailed QA guidelines for conventional radiotherapy and treatment planning. However, advanced treatment processes recently developed with emerging high technology have introduced new QA requirements that have not been addressed previously in the conventional QA program. Therefore, it is necessary to expand the existing QA guidelines to also include new considerations. Image-guided adaptive radiation therapy (IGART) is a closed-loop treatment process that is designed to include the individual treatment information, such as patient-specific anatomic variation and delivered dose assessed during the therapy course in treatment evaluation and planning optimization. Clinical implementation of IGART requires high levels of automation in image acquisition, registration, segmentation, treatment dose construction, and adaptive planning optimization, which brings new challenges to the conventional QA program. In this article, clinical QA procedures for IGART are outlined. The discussion focuses on the dynamic or four-dimensional aspects of the IGART process, avoiding overlap with conventional QA guidelines

Accelerated Deformable Registration of Repetitive MRI during Radiotherapy in Cervical Cancer

DEFF Research Database (Denmark)

Noe, Karsten Østergaard; Tanderup, Kari; Kiritsis, Christian

2006-01-01

Tumour regression and organ deformations during radiotherapy (RT) of cervical cancer represent major challenges regarding accurate conformation and calculation of dose when using image-guided adaptive radiotherapy. Deformable registration algorithms are able to handle organ deformations, which can...... be useful with advanced tools such as auto segmentation of organs and dynamic adaptation of radiotherapy. The aim of this study was to accelerate and validate deformable registration in MRI-based image-guided radiotherapy of cervical cancer.    ...

Image guided, adaptive, accelerated, high dose brachytherapy as model for advanced small volume radiotherapy

International Nuclear Information System (INIS)

Haie-Meder, Christine; Siebert, Frank-Andre; Poetter, Richard

2011-01-01

Brachytherapy has consistently provided a very conformal radiation therapy modality. Over the last two decades this has been associated with significant improvements in imaging for brachytherapy applications (prostate, gynecology), resulting in many positive advances in treatment planning, application techniques and clinical outcome. This is emphasized by the increased use of brachytherapy in Europe with gynecology as continuous basis and prostate and breast as more recently growing fields. Image guidance enables exact knowledge of the applicator together with improved visualization of tumor and target volumes as well as of organs at risk providing the basis for very individualized 3D and 4D treatment planning. In this commentary the most important recent developments in prostate, gynecological and breast brachytherapy are reviewed, with a focus on European recent and current research aiming at the definition of areas for important future research. Moreover the positive impact of GEC-ESTRO recommendations and the highlights of brachytherapy physics are discussed what altogether presents a full overview of modern image guided brachytherapy. An overview is finally provided on past and current international brachytherapy publications focusing on 'Radiotherapy and Oncology'. These data show tremendous increase in almost all research areas over the last three decades strongly influenced recently by translational research in regard to imaging and technology. In order to provide high level clinical evidence for future brachytherapy practice the strong need for comprehensive prospective clinical research addressing brachytherapy issues is high-lighted.

Clinical Experience With Image-Guided Radiotherapy in an Accelerated Partial Breast Intensity-Modulated Radiotherapy Protocol

International Nuclear Information System (INIS)

Leonard, Charles E.; Tallhamer, Michael M.S.; Johnson, Tim; Hunter, Kari C.M.D.; Howell, Kathryn; Kercher, Jane; Widener, Jodi; Kaske, Terese; Paul, Devchand; Sedlacek, Scot; Carter, Dennis L.

2010-01-01

Purpose: To explore the feasibility of fiducial markers for the use of image-guided radiotherapy (IGRT) in an accelerated partial breast intensity modulated radiotherapy protocol. Methods and Materials: Nineteen patients consented to an institutional review board approved protocol of accelerated partial breast intensity-modulated radiotherapy with fiducial marker placement and treatment with IGRT. Patients (1 patient with bilateral breast cancer; 20 total breasts) underwent ultrasound guided implantation of three 1.2- x 3-mm gold markers placed around the surgical cavity. For each patient, table shifts (inferior/superior, right/left lateral, and anterior/posterior) and minimum, maximum, mean error with standard deviation were recorded for each of the 10 BID treatments. The dose contribution of daily orthogonal films was also examined. Results: All IGRT patients underwent successful marker placement. In all, 200 IGRT treatment sessions were performed. The average vector displacement was 4 mm (range, 2-7 mm). The average superior/inferior shift was 2 mm (range, 0-5 mm), the average lateral shift was 2 mm (range, 1-4 mm), and the average anterior/posterior shift was 3 mm (range, 1 5 mm). Conclusions: This study shows that the use of IGRT can be successfully used in an accelerated partial breast intensity-modulated radiotherapy protocol. The authors believe that this technique has increased daily treatment accuracy and permitted reduction in the margin added to the clinical target volume to form the planning target volume.

18F-Fdg-PET-guided Planning and Re-Planning (Adaptive) Radiotherapy in Head and Neck Cancer: Current State of Art.

Science.gov (United States)

Farina, Eleonora; Ferioli, Martina; Castellucci, Paolo; Farina, Arianna; Zanirato Rambaldi, Giuseppe; Cilla, Savino; Cammelli, Silvia; Fanti, Stefano; Morganti, Alessio G

2017-12-01

A review of the literature is proposed as a contribution to current knowledge on technical, physical, and clinical issues about PET-guided planning and re-planning radiotherapy (RT) in head and neck cancer. PubMed and Scopus electronic databases were searched for articles including clinical trials. Search terms were "gross tumor volume (GTV) delineation", "head and neck cancer", "radiotherapy", "adaptive radiotherapy" in combination with "PET". A 18 F-FDG-PET and CT-scan comparison in GTV definition for RT planning of head and neck cancer was shown in twenty-seven clinical trials with a total of 712 patients. Only two clinical trials focused on PET-guided adaptive radiotherapy (ART) with a total of 31 patients. 18 F-FDG-PET is able to achieve an accurate and precise definition of GTV boundaries during RT planning, especially in combination with CT-scan. ART strategies are proposed to evaluate tumor volume changes, plan boost irradiation on metabolically active residual neoplasm and protect organs at risk (OaRs). Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

Automatic block-matching registration to improve lung tumor localization during image-guided radiotherapy

Science.gov (United States)

Robertson, Scott Patrick

To improve relatively poor outcomes for locally-advanced lung cancer patients, many current efforts are dedicated to minimizing uncertainties in radiotherapy. This enables the isotoxic delivery of escalated tumor doses, leading to better local tumor control. The current dissertation specifically addresses inter-fractional uncertainties resulting from patient setup variability. An automatic block-matching registration (BMR) algorithm is implemented and evaluated for the purpose of directly localizing advanced-stage lung tumors during image-guided radiation therapy. In this algorithm, small image sub-volumes, termed "blocks", are automatically identified on the tumor surface in an initial planning computed tomography (CT) image. Each block is independently and automatically registered to daily images acquired immediately prior to each treatment fraction. To improve the accuracy and robustness of BMR, this algorithm incorporates multi-resolution pyramid registration, regularization with a median filter, and a new multiple-candidate-registrations technique. The result of block-matching is a sparse displacement vector field that models local tissue deformations near the tumor surface. The distribution of displacement vectors is aggregated to obtain the final tumor registration, corresponding to the treatment couch shift for patient setup correction. Compared to existing rigid and deformable registration algorithms, the final BMR algorithm significantly improves the overlap between target volumes from the planning CT and registered daily images. Furthermore, BMR results in the smallest treatment margins for the given study population. However, despite these improvements, large residual target localization errors were noted, indicating that purely rigid couch shifts cannot correct for all sources of inter-fractional variability. Further reductions in treatment uncertainties may require the combination of high-quality target localization and adaptive radiotherapy.

Dual source and dual detector arrays tetrahedron beam computed tomography for image guided radiotherapy

International Nuclear Information System (INIS)

Kim, Joshua; Zhang, Tiezhi; Lu, Weiguo

2014-01-01

Cone-beam computed tomography (CBCT) is an important online imaging modality for image guided radiotherapy. But suboptimal image quality and the lack of a real-time stereoscopic imaging function limit its implementation in advanced treatment techniques, such as online adaptive and 4D radiotherapy. Tetrahedron beam computed tomography (TBCT) is a novel online imaging modality designed to improve on the image quality provided by CBCT. TBCT geometry is flexible, and multiple detector and source arrays can be used for different applications. In this paper, we describe a novel dual source–dual detector TBCT system that is specially designed for LINAC radiation treatment machines. The imaging system is positioned in-line with the MV beam and is composed of two linear array x-ray sources mounted aside the electrical portal imaging device and two linear arrays of x-ray detectors mounted below the machine head. The detector and x-ray source arrays are orthogonal to each other, and each pair of source and detector arrays forms a tetrahedral volume. Four planer images can be obtained from different view angles at each gantry position at a frame rate as high as 20 frames per second. The overlapped regions provide a stereoscopic field of view of approximately 10–15 cm. With a half gantry rotation, a volumetric CT image can be reconstructed having a 45 cm field of view. Due to the scatter rejecting design of the TBCT geometry, the system can potentially produce high quality 2D and 3D images with less radiation exposure. The design of the dual source–dual detector system is described, and preliminary results of studies performed on numerical phantoms and simulated patient data are presented. (paper)

[Head and neck adaptive radiotherapy].

Science.gov (United States)

Graff, P; Huger, S; Kirby, N; Pouliot, J

2013-10-01

Onboard volumetric imaging systems can provide accurate data of the patient's anatomy during a course of head and neck radiotherapy making it possible to assess the actual delivered dose and to evaluate the dosimetric impact of complex daily positioning variations and gradual anatomic changes such as geometric variations of tumors and normal tissues or shrinkage of external contours. Adaptive radiotherapy is defined as the correction of a patient's treatment planning to adapt for individual variations observed during treatment. Strategies are developed to selectively identify patients that require replanning because of an intolerable dosimetric drift. Automated tools are designed to limit time consumption. Deformable image registration algorithms are the cornerstones of these strategies, but a better understanding of their limits of validity is required before adaptive radiotherapy can be safely introduced to daily practice. Moreover, strict evaluation of the clinical benefits is yet to be proven. Copyright © 2013 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

Automatic prostate localization on cone-beam CT scans for high precision image-guided radiotherapy

NARCIS (Netherlands)

Smitsmans, Monique H. P.; de Bois, Josien; Sonke, Jan-Jakob; Betgen, Anja; Zijp, Lambert J.; Jaffray, David A.; Lebesque, Joos V.; van Herk, Marcel

2005-01-01

PURPOSE: Previously, we developed an automatic three-dimensional gray-value registration (GR) method for fast prostate localization that could be used during online or offline image-guided radiotherapy. The method was tested on conventional computed tomography (CT) scans. In this study, the

Five-year follow-up using a prostate stent as fiducial in image-guided radiotherapy of prostate cancer.

Science.gov (United States)

Carl, Jesper; Sander, Lotte

2015-06-01

To report results from the five-year follow-up on a previously reported study using image-guided radiotherapy (IGRT) of localized or locally advanced prostate cancer (PC) and a removable prostate stent as fiducial. Patients with local or locally advanced PC were treated using five-field 3D conformal radiotherapy (3DRT). The clinical target volumes (CTV) were treated to 78 Gy in 39 fractions using daily on-line image guidance (IG). Late genito-urinary (GU) and gastro-intestinal (GI) toxicities were scored using the radiotherapy oncology group (RTOG) score and the common toxicity score of adverse events (CTC) score. Urinary symptoms were also scored using the international prostate symptom score (IPSS). Median observation time was 5.4 year. Sixty-two of the 90 patients from the original study cohort were eligible for toxicity assessment. Overall survival, cancer-specific survival and biochemical freedom from failure were 85%, 96% and 80%, respectively at five years after radiotherapy. Late toxicity GU and GI RTOG scores≥2 were 5% and 0%. Comparing pre- and post-radiotherapy IPSS scores indicate that development in urinary symptoms after radiotherapy may be complex. Prostate image-guided radiotherapy using a prostate stent demonstrated survival data comparable with recently published data. GU and GI toxicities at five-year follow-up were low and comparable to the lowest toxicity rates reported. These findings support that the precision of the prostate stent technique is at least as good as other techniques. IPSS revealed a complex development in urinary symptoms after radiotherapy.

X-ray volumetric imaging in image-guided radiotherapy: The new standard in on-treatment imaging

International Nuclear Information System (INIS)

McBain, Catherine A.; Henry, Ann M.; Sykes, Jonathan; Amer, Ali; Marchant, Tom; Moore, Christopher M.; Davies, Julie; Stratford, Julia; McCarthy, Claire; Porritt, Bridget; Williams, Peter; Khoo, Vincent S.; Price, Pat

2006-01-01

Purpose: X-ray volumetric imaging (XVI) for the first time allows for the on-treatment acquisition of three-dimensional (3D) kV cone beam computed tomography (CT) images. Clinical imaging using the Synergy System (Elekta, Crawley, UK) commenced in July 2003. This study evaluated image quality and dose delivered and assessed clinical utility for treatment verification at a range of anatomic sites. Methods and Materials: Single XVIs were acquired from 30 patients undergoing radiotherapy for tumors at 10 different anatomic sites. Patients were imaged in their setup position. Radiation doses received were measured using TLDs on the skin surface. The utility of XVI in verifying target volume coverage was qualitatively assessed by experienced clinicians. Results: X-ray volumetric imaging acquisition was completed in the treatment position at all anatomic sites. At sites where a full gantry rotation was not possible, XVIs were reconstructed from projection images acquired from partial rotations. Soft-tissue definition of organ boundaries allowed direct assessment of 3D target volume coverage at all sites. Individual image quality depended on both imaging parameters and patient characteristics. Radiation dose ranged from 0.003 Gy in the head to 0.03 Gy in the pelvis. Conclusions: On-treatment XVI provided 3D verification images with soft-tissue definition at all anatomic sites at acceptably low radiation doses. This technology sets a new standard in treatment verification and will facilitate novel adaptive radiotherapy techniques

Dosimetric and geometric evaluation of a hybrid strategy of offline adaptive planning and online image guidance for prostate cancer radiotherapy

International Nuclear Information System (INIS)

Liu Han; Wu Qiuwen

2011-01-01

For prostate cancer patients, online image-guided (IG) radiotherapy has been widely used in clinic to correct the translational inter-fractional motion at each treatment fraction. For uncertainties that cannot be corrected online, such as rotation and deformation of the target volume, margins are still required to be added to the clinical target volume (CTV) for the treatment planning. Offline adaptive radiotherapy has been implemented to optimize the treatment for each individual patient based on the measurements at early stages of treatment process. It has been shown that offline adaptive radiotherapy can effectively reduce the required margin. Recently a hybrid strategy of offline adaptive replanning and online IG was proposed and the geometric evaluation was performed. It was found that the planning margins can further be reduced by 1-2 mm compared to online IG only strategy. The purpose of this study was to investigate the dosimetric benefits of such a hybrid strategy on the target and organs at risk. A total of 420 repeated helical computed tomography scans from 28 patients were included in the study. Both low-risk patients (LRP, CTV = prostate) and intermediate-risk patients (IRP, CTV = prostate + seminal vesicles, SV) were included in the simulation. Two registration methods, based on center-of-mass shift of prostate only and prostate plus SV, were performed for IRP. The intensity-modulated radiotherapy was used in the simulation. Criteria on both cumulative and fractional doses were evaluated. Furthermore, the geometric evaluation was extended to investigate the optimal number of fractions necessary to construct the internal target volume (ITV) for the hybrid strategy. The dosimetric margin improvement was smaller than its geometric counterpart and was in the range of 0-1 mm. The optimal number of fractions necessary for the ITV construction is 2 for LRPs and 3-4 for IRPs in a hypofractionation protocol. A new cumulative index of target volume was proposed

Image guided multibeam radiotherapy

International Nuclear Information System (INIS)

Freijo, J.L.

2008-01-01

This paper provides an outlook of the status of the first development stages for an updated design of radiotherapy conformal system based on tumor 3D images obtained as an output the last generation imaging machines as PET, CT and MR which offer a very valuable output in cancer diagnosis. Prospective evaluation of current software codes and acquisition of useful experience in surgical planning involves a multidisciplinary process as an initial and unavoidable stage to develop an expert software and user skills which assures the delivery of the radiation dose is done correctly in geometry and value in each voxel as a radiation protection basic condition. The validation of the images obtained has been done by the production of anatomical models of interest regions by rapid proto typing of the 3D segmented images and its evaluation by contrasting with the real regions during surgical procedures. (author)

Longitudinal diffusion MRI for treatment response assessment: Preliminary experience using an MRI-guided tri-cobalt 60 radiotherapy system.

Science.gov (United States)

Yang, Yingli; Cao, Minsong; Sheng, Ke; Gao, Yu; Chen, Allen; Kamrava, Mitch; Lee, Percy; Agazaryan, Nzhde; Lamb, James; Thomas, David; Low, Daniel; Hu, Peng

2016-03-01

To demonstrate the preliminary feasibility of a longitudinal diffusion magnetic resonance imaging (MRI) strategy for assessing patient response to radiotherapy at 0.35 T using an MRI-guided radiotherapy system (ViewRay). Six patients (three head and neck cancer, three sarcoma) who underwent fractionated radiotherapy were enrolled in this study. A 2D multislice spin echo single-shot echo planar imaging diffusion pulse sequence was implemented on the ViewRay system and tested in phantom studies. The same pulse sequence was used to acquire longitudinal diffusion data (every 2-5 fractions) on the six patients throughout the entire course of radiotherapy. The reproducibility of the apparent diffusion coefficient (ADC) measurements was assessed using reference regions and the temporal variations of the tumor ADC values were evaluated. In diffusion phantom studies, the ADC values measured on the ViewRay system matched well with reference ADC values with ViewRay MRI. Larger patient cohort studies are warranted to correlate the longitudinal diffusion measurements to patient outcomes. Such an approach may enable response-guided adaptive radiotherapy.

Commissioning an image-guided localization system for radiotherapy

International Nuclear Information System (INIS)

Phillips, Mark H.; Singer, Karen; Miller, Elizabeth; Stelzer, Keith

2000-01-01

Purpose: To describe the design and commissioning of a system for the treatment of classes of tumors that require highly accurate target localization during a course of fractionated external-beam therapy. This system uses image-guided localization techniques in the linac vault to position patients being treated for cranial tumors using stereotactic radiotherapy, conformal radiotherapy, and intensity-modulated radiation therapy techniques. Design constraints included flexibility in the use of treatment-planning software, accuracy and precision of repeat localization, limits on the time and human resources needed to use the system, and ease of use. Methods and Materials: A commercially marketed, stereotactic radiotherapy system, based on a system designed at the University of Florida, Gainesville, was adapted for use at the University of Washington Medical Center. A stereo pair of cameras in the linac vault were used to detect the position and orientation of an array of fiducial markers that are attached to a patient's biteblock. The system was modified to allow the use of either a treatment-planning system designed for stereotactic treatments, or a general, three-dimensional radiation therapy planning program. Measurements of the precision and accuracy of the target localization, dose delivery, and patient positioning were made using a number of different jigs and devices. Procedures were developed for the safe and accurate clinical use of the system. Results: The accuracy of the target localization is comparable to that of other treatment-planning systems. Gantry sag, which cannot be improved, was measured to be 1.7 mm, which had the effect of broadening the dose distribution, as confirmed by a comparison of measurement and calculation. The accuracy of positioning a target point in the radiation field was 1.0 ± 0.2 mm. The calibration procedure using the room-based lasers had an accuracy of 0.76 mm, and using a floor-based radiosurgery system it was 0.73 mm

Commissioning and quality assurance of the x-ray volume imaging system of an image-guided radiotherapy capable linear accelerator

International Nuclear Information System (INIS)

Muralidhar, K.R.; Narayana Murthy, P.; Kumar, Rajneesh

2008-01-01

An Image-Guided Radiotherapy-capable linear accelerator (Elekta Synergy) was installed at our hospital, which is equipped with a kV x-ray volume imaging (XVI) system and electronic portal imaging device (iViewGT). The objective of this presentation is to describe the results of commissioning measurements carried out on the XVI facility to verify the manufacturer's specifications and also to evolve a QA schedule which can be used to test its performance routinely. The QA program consists of a series of tests (safety features, geometric accuracy, and image quality). These tests were found to be useful to assess the performance of the XVI system and also proved that XVI system is very suitable for image-guided high-precision radiation therapy. (author)

Commissioning and quality assurance of the X-ray volume Imaging system of an image-guided radiotherapy capable linear accelerator

Directory of Open Access Journals (Sweden)

Muralidhar K

2008-01-01

Full Text Available An Image-Guided Radiotherapy-capable linear accelerator (Elekta Synergy was installed at our hospital, which is equipped with a kV x-ray volume imaging (XVI system and electronic portal imaging device (iViewGT. The objective of this presentation is to describe the results of commissioning measurements carried out on the XVI facility to verify the manufacturer′s specifications and also to evolve a QA schedule which can be used to test its performance routinely. The QA program consists of a series of tests (safety features, geometric accuracy, and image quality. These tests were found to be useful to assess the performance of the XVI system and also proved that XVI system is very suitable for image-guided high-precision radiation therapy.

Improvement in toxicity in high risk prostate cancer patients treated with image-guided intensity-modulated radiotherapy compared to 3D conformal radiotherapy without daily image guidance

International Nuclear Information System (INIS)

Sveistrup, Joen; Rosenschöld, Per Munck af; Deasy, Joseph O; Oh, Jung Hun; Pommer, Tobias; Petersen, Peter Meidahl; Engelholm, Svend Aage

2014-01-01

Image-guided radiotherapy (IGRT) facilitates the delivery of a very precise radiation dose. In this study we compare the toxicity and biochemical progression-free survival between patients treated with daily image-guided intensity-modulated radiotherapy (IG-IMRT) and 3D conformal radiotherapy (3DCRT) without daily image guidance for high risk prostate cancer (PCa). A total of 503 high risk PCa patients treated with radiotherapy (RT) and endocrine treatment between 2000 and 2010 were retrospectively reviewed. 115 patients were treated with 3DCRT, and 388 patients were treated with IG-IMRT. 3DCRT patients were treated to 76 Gy and without daily image guidance and with 1–2 cm PTV margins. IG-IMRT patients were treated to 78 Gy based on daily image guidance of fiducial markers, and the PTV margins were 5–7 mm. Furthermore, the dose-volume constraints to both the rectum and bladder were changed with the introduction of IG-IMRT. The 2-year actuarial likelihood of developing grade > = 2 GI toxicity following RT was 57.3% in 3DCRT patients and 5.8% in IG-IMRT patients (p < 0.001). For GU toxicity the numbers were 41.8% and 29.7%, respectively (p = 0.011). On multivariate analysis, 3DCRT was associated with a significantly increased risk of developing grade > = 2 GI toxicity compared to IG-IMRT (p < 0.001, HR = 11.59 [CI: 6.67-20.14]). 3DCRT was also associated with an increased risk of developing GU toxicity compared to IG-IMRT. The 3-year actuarial biochemical progression-free survival probability was 86.0% for 3DCRT and 90.3% for IG-IMRT (p = 0.386). On multivariate analysis there was no difference in biochemical progression-free survival between 3DCRT and IG-IMRT. The difference in toxicity can be attributed to the combination of the IMRT technique with reduced dose to organs-at-risk, daily image guidance and margin reduction

Credentialing of radiotherapy centres for a clinical trial of adaptive radiotherapy for bladder cancer (TROG 10.01)

International Nuclear Information System (INIS)

Kron, Tomas; Pham, Daniel; Roxby, Paul; Rolfo, Aldo; Foroudi, Farshad

2012-01-01

Background: Daily variations in bladder filling make conformal treatment of bladder cancer challenging. On-line adaptive radiotherapy with a choice of plans has been demonstrated to reduce small bowel irradiation in single institution trials. In order to support a multicentre feasibility clinical trial on adaptive radiotherapy for bladder cancer (TROG 10.01) a credentialing programme was developed for centres wishing to participate. Methods: The credentialing programme entails three components: a facility questionnaire; a planning exercise which tests the ability of centres to create three adaptive plans based on a planning and five cone beam CTs; and a site visit during which image quality, imaging dose and image guidance procedures are assessed. Image quality and decision making were tested using customised inserts for a Perspex phantom (Modus QUASAR) that mimic different bladder sizes. Dose was assessed in the same phantom using thermoluminescence dosimetry (TLD). Results: All 12 centres participating in the full credentialing programme were able to generate appropriate target volumes in the planning exercise and identify the correct target volume and position the bladder phantom in the phantom within 3 mm accuracy. None of the imaging doses exceeded the limit of 5 cGy with a CT on rails system having the lowest overall dose. Conclusion: A phantom mimicking the decision making process for adaptive radiotherapy was found to be well suited during site visits for credentialing of centres participating in a clinical trial of adaptive radiotherapy for bladder cancer. Combined with a planning exercise the site visit allowed testing the ability of centres to create adaptive treatment plans and make appropriate decisions based on the volumetric images acquired at treatment.

Feasibility of intensity-modulated and image-guided radiotherapy for locally advanced esophageal cancer

International Nuclear Information System (INIS)

Nguyen, Nam P; Desai, Anand; Smith-Raymond, Lexie; Jang, Siyoung; Vock, Jacqueline; Vinh-Hung, Vincent; Chi, Alexander; Vos, Paul; Pugh, Judith; Vo, Richard A; Ceizyk, Misty

2014-01-01

In this study the feasibility of intensity-modulated radiotherapy (IMRT) and tomotherapy-based image-guided radiotherapy (IGRT) for locally advanced esophageal cancer was assessed. A retrospective study of ten patients with locally advanced esophageal cancer who underwent concurrent chemotherapy with IMRT (1) and IGRT (9) was conducted. The gross tumor volume was treated to a median dose of 70 Gy (62.4-75 Gy). At a median follow-up of 14 months (1-39 months), three patients developed local failures, six patients developed distant metastases, and complications occurred in two patients (1 tracheoesophageal fistula, 1 esophageal stricture requiring repeated dilatations). No patients developed grade 3-4 pneumonitis or cardiac complications. IMRT and IGRT may be effective for the treatment of locally advanced esophageal cancer with acceptable complications

Automatic Delineation of On-Line Head-And-Neck Computed Tomography Images: Toward On-Line Adaptive Radiotherapy

International Nuclear Information System (INIS)

Zhang Tiezhi; Chi Yuwei; Meldolesi, Elisa; Yan Di

2007-01-01

Purpose: To develop and validate a fully automatic region-of-interest (ROI) delineation method for on-line adaptive radiotherapy. Methods and Materials: On-line adaptive radiotherapy requires a robust and automatic image segmentation method to delineate ROIs in on-line volumetric images. We have implemented an atlas-based image segmentation method to automatically delineate ROIs of head-and-neck helical computed tomography images. A total of 32 daily computed tomography images from 7 head-and-neck patients were delineated using this automatic image segmentation method. Manually drawn contours on the daily images were used as references in the evaluation of automatically delineated ROIs. Two methods were used in quantitative validation: (1) the dice similarity coefficient index, which indicates the overlapping ratio between the manually and automatically delineated ROIs; and (2) the distance transformation, which yields the distances between the manually and automatically delineated ROI surfaces. Results: Automatic segmentation showed agreement with manual contouring. For most ROIs, the dice similarity coefficient indexes were approximately 0.8. Similarly, the distance transformation evaluation results showed that the distances between the manually and automatically delineated ROI surfaces were mostly within 3 mm. The distances between two surfaces had a mean of 1 mm and standard deviation of <2 mm in most ROIs. Conclusion: With atlas-based image segmentation, it is feasible to automatically delineate ROIs on the head-and-neck helical computed tomography images in on-line adaptive treatments

A new fiducial marker for Image-guided radiotherapy of prostate cancer: Clinical experience

Energy Technology Data Exchange (ETDEWEB)

Carl, Jesper; Nielsen, Jane; Holmberg, Mats; Hoejkjaer Larsen, Erik; Fabrin, Knud; Fisker, Rune V. (Dept. of Medical Physics, Oncology, Aalborg Hospital (Denmark))

2008-08-15

Background. A new fiducial marker for image guided radiotherapy (IGRT) based on a removable prostate stent made of Ni Ti has been developed during two previous clinical feasibility studies. The marker is currently being evaluated for IGRT treatment in a third clinical study. Method. The new marker is used to co-register MR and planning CT scans with high accuracy in the region around the prostate. The co-registered MR-CT volumes are used for delineation of GTV before planning. In each treatment session the IGRT system is used to position the patient before treatment. The IGRT system use a stereo pair of kV images matched to corresponding Digital Reconstructed Radiograms (DRR) from the planning CT scan. The match is done using mutual gray scale information. The pair of DRR's for positioning is created in the IGRT system with a threshold in the Look Up Table (LUT). The resulting match provides the necessary shift in couch coordinates to position the stent with an accuracy of 1-2 mm within the planned position. Results. At the present time 39 patients have received the new marker. Of the 39 one has migrated to the bladder. Deviations of more than 5 mm between CTV outlined on CT and MR are seen in several cases and in anterior-posterior (AP), left-right (LR) and cranial-caudal (CC) directions. Intra-fraction translation movements up to +/- 3 mm are seen as well. As the stent is also clearly visible on images taken with high voltage x-rays using electronic portal images devices (EPID), the positioning has been verified independently of the IGRT system. Discussion. The preliminary result of an on going clinical study of a Ni Ti prostate stent, potentially a new fiducial marker for image guided radiotherapy, looks promising. The risk of migration appears to be much lower compared to previous designs

A new fiducial marker for Image-guided radiotherapy of prostate cancer: clinical experience.

Science.gov (United States)

Carl, Jesper; Nielsen, Jane; Holmberg, Mats; Højkjaer Larsen, Erik; Fabrin, Knud; Fisker, Rune V

2008-01-01

A new fiducial marker for image guided radiotherapy (IGRT) based on a removable prostate stent made of Ni Ti has been developed during two previous clinical feasibility studies. The marker is currently being evaluated for IGRT treatment in a third clinical study. The new marker is used to co-register MR and planning CT scans with high accuracy in the region around the prostate. The co-registered MR-CT volumes are used for delineation of GTV before planning. In each treatment session the IGRT system is used to position the patient before treatment. The IGRT system use a stereo pair of kV images matched to corresponding Digital Reconstructed Radiograms (DRR) from the planning CT scan. The match is done using mutual gray scale information. The pair of DRR's for positioning is created in the IGRT system with a threshold in the Look Up Table (LUT). The resulting match provides the necessary shift in couch coordinates to position the stent with an accuracy of 1-2 mm within the planned position. At the present time 39 patients have received the new marker. Of the 39 one has migrated to the bladder. Deviations of more than 5 mm between CTV outlined on CT and MR are seen in several cases and in anterior-posterior (AP), left-right (LR) and cranial-caudal (CC) directions. Intra-fraction translation movements up to +/- 3 mm are seen as well. As the stent is also clearly visible on images taken with high voltage x-rays using electronic portal images devices (EPID), the positioning has been verified independently of the IGRT system. The preliminary result of an on going clinical study of a Ni Ti prostate stent, potentially a new fiducial marker for image guided radiotherapy, looks promising. The risk of migration appears to be much lower compared to previous designs.

A new fiducial marker for Image-guided radiotherapy of prostate cancer: Clinical experience

International Nuclear Information System (INIS)

Carl, Jesper; Nielsen, Jane; Holmberg, Mats; Hoejkjaer Larsen, Erik; Fabrin, Knud; Fisker, Rune V.

2008-01-01

Background. A new fiducial marker for image guided radiotherapy (IGRT) based on a removable prostate stent made of Ni Ti has been developed during two previous clinical feasibility studies. The marker is currently being evaluated for IGRT treatment in a third clinical study. Method. The new marker is used to co-register MR and planning CT scans with high accuracy in the region around the prostate. The co-registered MR-CT volumes are used for delineation of GTV before planning. In each treatment session the IGRT system is used to position the patient before treatment. The IGRT system use a stereo pair of kV images matched to corresponding Digital Reconstructed Radiograms (DRR) from the planning CT scan. The match is done using mutual gray scale information. The pair of DRR's for positioning is created in the IGRT system with a threshold in the Look Up Table (LUT). The resulting match provides the necessary shift in couch coordinates to position the stent with an accuracy of 1-2 mm within the planned position. Results. At the present time 39 patients have received the new marker. Of the 39 one has migrated to the bladder. Deviations of more than 5 mm between CTV outlined on CT and MR are seen in several cases and in anterior-posterior (AP), left-right (LR) and cranial-caudal (CC) directions. Intra-fraction translation movements up to +/- 3 mm are seen as well. As the stent is also clearly visible on images taken with high voltage x-rays using electronic portal images devices (EPID), the positioning has been verified independently of the IGRT system. Discussion. The preliminary result of an on going clinical study of a Ni Ti prostate stent, potentially a new fiducial marker for image guided radiotherapy, looks promising. The risk of migration appears to be much lower compared to previous designs

On-line MRI guidance for Radiotherapy

NARCIS (Netherlands)

Crijns, S.P.M.

2013-01-01

Image-guided radiotherapy has the potential to increase success of treatment by decreasing uncertainties concerning tumour position and shape. MRI is the modality of choice when it comes to imaging for tumour delineation and characterisation, set-up correction, treatment plan adaptation, response

WE-G-BRF-01: Adaptation to Intrafraction Tumor Deformation During Intensity-Modulated Radiotherapy: First Proof-Of-Principle Demonstration

International Nuclear Information System (INIS)

Ge, Y; OBrien, R; Shieh, C; Booth, J; Keall, P

2014-01-01

Purpose: Intrafraction tumor deformation limits targeting accuracy in radiotherapy and cannot be adapted to by current motion management techniques. This study simulated intrafractional treatment adaptation to tumor deformations using a dynamic Multi-Leaf Collimator (DMLC) tracking system during Intensity-modulated radiation therapy (IMRT) treatment for the first time. Methods: The DMLC tracking system was developed to adapt to the intrafraction tumor deformation by warping the planned beam aperture guided by the calculated deformation vector field (DVF) obtained from deformable image registration (DIR) at the time of treatment delivery. Seven single phantom deformation images up to 10.4 mm deformation and eight tumor system phantom deformation images up to 21.5 mm deformation were acquired and used in tracking simulation. The intrafraction adaptation was simulated at the DMLC tracking software platform, which was able to communicate with the image registration software, reshape the instantaneous IMRT field aperture and log the delivered MLC fields.The deformation adaptation accuracy was evaluated by a geometric target coverage metric defined as the sum of the area incorrectly outside and inside the reference aperture. The incremental deformations were arbitrarily determined to take place equally over the delivery interval. The geometric target coverage of delivery with deformation adaptation was compared against the delivery without adaptation. Results: Intrafraction deformation adaptation during dynamic IMRT plan delivery was simulated for single and system deformable phantoms. For the two particular delivery situations, over the treatment course, deformation adaptation improved the target coverage by 89% for single target deformation and 79% for tumor system deformation compared with no-tracking delivery. Conclusion: This work demonstrated the principle of real-time tumor deformation tracking using a DMLC. This is the first step towards the development of an

The Role of Seminal Vesicle Motion in Target Margin Assessment for Online Image-Guided Radiotherapy for Prostate Cancer

International Nuclear Information System (INIS)

Liang Jian; Wu Qiuwen; Yan Di

2009-01-01

Purpose: For patients with intermediate- and high-risk prostate cancer, the seminal vesicles (SVs) are included in the clinical target volume (CTV). The purposes of this study are to investigate interfraction motion characteristics of the SVs and determine proper margins for online computed tomography image guidance. Methods and Materials: Twenty-four patients, each with 16 daily helical computed tomography scans, were included in this study. A binary image mask was used for image registration to determine daily organ motion. Two online image-guided radiotherapy strategies (prostate only and prostate + SVs) were simulated in a hypofractionated scheme. Three margin designs were studied for both three-dimensional conformal radiotherapy and intensity-modulated radiotherapy (IMRT). In prostate-only guidance, Margin A was uniformly applied to the whole CTV, and Margin B was applied to the SVs with a fixed 3-mm prostate margin. In prostate plus SV guidance, Margin C was uniformly applied to the CTV. The minimum margins were sought to satisfy the criterion that minimum cumulative CTV dose be more than those of the planning target volume in the plan for greater than 95% of patients. Results: The prostate and SVs move significantly more in the anterior-posterior and superior-inferior than right-left directions. The anterior-posterior motion of the prostate and SVs correlated (R 2 = 0.7). The SVs move significantly more than the prostate. The minimum margins found were 2.5 mm for three-dimensional conformal radiotherapy and 4.5, 4.5, and 3.0 mm for Margins A, B, and C for IMRT, respectively. Margins for IMRT were larger, but the irradiated volume and doses to critical structures were smaller. Minimum margins of 4.5 mm to the SVs and 3 mm to the prostate are recommended for IMRT with prostate-only guidance. Conclusions: The SVs move independently from the prostate gland, and additional margins are necessary for image-guided radiotherapy

Image-guided radiotherapy and motion management in lung cancer

DEFF Research Database (Denmark)

Korreman, Stine

2015-01-01

In this review, image guidance and motion management in radiotherapy for lung cancer is discussed. Motion characteristics of lung tumours and image guidance techniques to obtain motion information are elaborated. Possibilities for management of image guidance and motion in the various steps...

Cost minimisation analysis: kilovoltage imaging with automated repositioning versus electronic portal imaging in image-guided radiotherapy for prostate cancer.

Science.gov (United States)

Gill, S; Younie, S; Rolfo, A; Thomas, J; Siva, S; Fox, C; Kron, T; Phillips, D; Tai, K H; Foroudi, F

2012-10-01

To compare the treatment time and cost of prostate cancer fiducial marker image-guided radiotherapy (IGRT) using orthogonal kilovoltage imaging (KVI) and automated couch shifts and orthogonal electronic portal imaging (EPI) and manual couch shifts. IGRT treatment delivery times were recorded automatically on either unit. Costing was calculated from real costs derived from the implementation of a new radiotherapy centre. To derive cost per minute for EPI and KVI units the total annual setting up and running costs were divided by the total annual working time. The cost per IGRT fraction was calculated by multiplying the cost per minute by the duration of treatment. A sensitivity analysis was conducted to test the robustness of our analysis. Treatment times without couch shift were compared. Time data were analysed for 8648 fractions, 6057 from KVI treatment and 2591 from EPI treatment from a total of 294 patients. The median time for KVI treatment was 6.0 min (interquartile range 5.1-7.4 min) and for EPI treatment it was 10.0 min (interquartile range 8.3-11.8 min) (P value time for EPI was 8.8 min and for KVI was 5.1 min. Treatment time is less on KVI units compared with EPI units. This is probably due to automation of couch shift and faster evaluation of imaging on KVI units. Annual running costs greatly outweigh initial setting up costs and therefore the cost per fraction was less with KVI, despite higher initial costs. The selection of appropriate IGRT equipment can make IGRT practical within radiotherapy departments. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

Multifractionated image-guided and stereotactic intensity-modulated radiotherapy of paraspinal tumors: A preliminary report

International Nuclear Information System (INIS)

Yamada, Yoshiya; Lovelock, D. Michael; Yenice, Kamil M.; Bilsky, Mark H.; Hunt, Margaret A.; Zatcky, Joan; Leibel, Steven A.

2005-01-01

Purpose: The use of image-guided and stereotactic intensity-modulated radiotherapy (IMRT) techniques have made the delivery of high-dose radiation to lesions within close proximity to the spinal cord feasible. This report presents clinical and physical data regarding the use of IMRT coupled with noninvasive body frames (stereotactic and image-guided) for multifractionated radiotherapy. Methods and Materials: The Memorial Sloan-Kettering Cancer Center (Memorial) stereotactic body frame (MSBF) and Memorial body cradle (MBC) have been developed as noninvasive immobilizing devices for paraspinal IMRT using stereotactic (MSBF) and image-guided (MBC) techniques. Patients were either previously irradiated or prescribed doses beyond spinal cord tolerance (54 Gy in standard fractionation) and had unresectable gross disease involving the spinal canal. The planning target volume (PTV) was the gross tumor volume with a 1 cm margin. The PTV was not allowed to include the spinal cord contour. All treatment planning was performed using software developed within the institution. Isocenter verification was performed with an in-room computed tomography scan (MSBF) or electronic portal imaging devices, or both. Patients were followed up with serial magnetic resonance imaging every 3-4 months, and no patients were lost to follow-up. Kaplan-Meier statistics were used for analysis of clinical data. Results: Both the MSBF and MBC were able to provide setup accuracy within 2 mm. With a median follow-up of 11 months, 35 patients (14 primary and 21 secondary malignancies) underwent treatment. The median dose previously received was 3000 cGy in 10 fractions. The median dose prescribed for these patients was 2000 cGy/5 fractions (2000-3000 cGy), which provided a median PTV V100 of 88%. In previously unirradiated patients, the median prescribed dose was 7000 cGy (5940-7000 cGy) with a median PTV V100 of 90%. The median Dmax to the cord was 34% and 68% for previously irradiated and never

Target coverage in image-guided stereotactic body radiotherapy of liver tumors.

Science.gov (United States)

Wunderink, Wouter; Méndez Romero, Alejandra; Vásquez Osorio, Eliana M; de Boer, Hans C J; Brandwijk, René P; Levendag, Peter C; Heijmen, Ben J M

2007-05-01

To determine the effect of image-guided procedures (with computed tomography [CT] and electronic portal images before each treatment fraction) on target coverage in stereotactic body radiotherapy for liver patients using a stereotactic body frame (SBF) and abdominal compression. CT guidance was used to correct for day-to-day variations in the tumor's mean position in the SBF. By retrospectively evaluating 57 treatment sessions, tumor coverage, as obtained with the clinically applied CT-guided protocol, was compared with that of alternative procedures. The internal target volume-plus (ITV(+)) was introduced to explicitly include uncertainties in tumor delineations resulting from CT-imaging artifacts caused by residual respiratory motion. Tumor coverage was defined as the volume overlap of the ITV(+), derived from a tumor delineated in a treatment CT scan, and the planning target volume. Patient stability in the SBF, after acquisition of the treatment CT scan, was evaluated by measuring the displacement of the bony anatomy in the electronic portal images relative to CT. Application of our clinical protocol (with setup corrections following from manual measurements of the distances between the contours of the planning target volume and the daily clinical target volume in three orthogonal planes, multiple two-dimensional) increased the frequency of nearly full (> or = 99%) ITV(+) coverage to 77% compared with 63% without setup correction. An automated three-dimensional method further improved the frequency to 96%. Patient displacements in the SBF were generally small (design, patient stability in the SBF should be verified with portal imaging.

Interactive adaptation of a volumetric imaging radiotherapy treatment: development and validation of tools for its implementation in clinical routine

International Nuclear Information System (INIS)

Huger, Sandrine

2013-01-01

Changing anatomy during radiotherapy can lead to significant dosimetric consequences for organs at risk (OARs) and/or target volumes. Adaptive radiotherapy can compensate for these variations however its deployment for clinical work is hampered by the increased workload for the medical staff and there is still no commercialized software available for clinical use. We developed a simple in vivo dosimetric alert tool allowing rapid identification of patients who might benefit from an adaptive radiotherapy. Dosimetric evaluation of delivered treatment has been conducted onto 3D on board imaging (CBCT) whose dose calculation accuracy has been evaluated. The tool does not require a new volume of interest delineation. Tool alert is based on objectives and quantifiable criteria defined by the exceeding volumes of interest dose thresholds. Tool precision and detectability have been validated and applied in a retrospective study on 10 head and neck patients. The tool allows detecting patients where an adaptive treatment could have been considered. In its clinical implementation, adaptive radiotherapy process requires deformable matching algorithms to follow patient local's deformations occurring during treatment. Nevertheless, their use has not been validated. We conducted an evaluation of the Block Matching deformable algorithm, suitable for multimodality imaging (CT/CBCT), in comparison to rigid algorithm. A study has been conducted for 10 head and neck patients based on volume of interest contours comparison for 76 CBCT. Similarity parameters used consisted on Dice Similarity Index, Robust Hausdorff Distance (in mm) and the absolute volume difference (in cc). (author)

Towards real-time plan adaptation for MRI-guided radiotherapy

NARCIS (Netherlands)

Kontaxis, Charis

2017-01-01

The introduction of hybrid MRI and linear accelerator (MRI-linac) machines enables the online volumetric imaging during radiation delivery with the superior soft tissue contrast of the diagnostic quality MRI. In this context, conventional radiotherapy workflow will gradually transfer from an offline

Feasibility of dose planning using CBCT images combined with MSCT images for adaptive radiotherapy

International Nuclear Information System (INIS)

Usui, Keisuke; Kunieda, Etsuo; Ogawa, Koichi

2013-01-01

If a kilo-voltage cone-beam computed tomography (CBCT) system mounted on a linear accelerator becomes available for dose calculation, we can confirm the dose distribution of treatment in each day by referring it to the initially planned dose distribution. In this paper, we verified the validity of the calculation method using CBCT images combined with multi-slice CT images. To evaluate the accuracy of calculated dose distribution, γ analysis, distance-to-agreement analysis and dose-volume-histogram analysis were used as the conventional dose calculation methods using CBCT images. The results showed that the dose distribution calculated by our proposed method agreed with the initial treatment plan better compared with the other methods. In addition, our method was so stable that the calculated dose distribution was insensitive to variations in clinical conditions. We demonstrated the feasibility of our proposed method for adaptive radiotherapy. (author)

Patient dose in image guided radiotherapy: Monte Carlo study of the CBCT dose contribution

OpenAIRE

Leotta, Salvatore; Amato, Ernesto; Settineri, Nicola; Basile, Emilia; Italiano, Antonio; Auditore, Lucrezia; Santacaterina, Anna; Pergolizzi, Stefano

2018-01-01

Image Guided RadioTherapy (IGRT) is a technique whose diffusion is growing thanks to the well-recognized gain in accuracy of dose delivery. However, multiple Cone Beam Computed Tomography (CBCT) scans add dose to patients, and its contribution has to be assessed and minimized. Aim of our work was to evaluate, through Monte Carlo simulations, organ doses in IGRT due to CBCT and therapeutic MV irradiation in head-neck, thorax and pelvis districts. We developed a Monte Carlo simulation in GAMOS ...

Study of inter-fractional variations and adaptive radiotherapy in pancreatic cancer

International Nuclear Information System (INIS)

Yang Chengliang; Wang Jianhua; Li Dingjie; Mao Ronghu; Li, X. Allen

2012-01-01

Objective: To quantitatively characterize the inter-fractional anatomy variations and advantages of dosimetry for the adaptive radiotherapy in pancreatic cancer. Methods: A total of 226 daily CT images acquired from 10 patients with pancreatic cancer treated with image-guided radiotherapy were analyzed retrospectively. Targets and organs at risk (OARs) were delineated by the atlas-based automatic segmentation and modified by the skilled physician. Various parameters,including the center of mass (COM) distance, the maximal overlap ratio (MOR) and the Dice coefficient (DC), were used to quantify the inter-fractional organ displacement and deformation. The adaptive radiation therapy (ART) was applied to handle the daily GT images. The dose distributions parameters from the ART plan were compared with those from the repositioning plan. Results: The inter-fractional anatomy variations of pancreas head were obvious in the pancreatic cancer irradiation. The mean COM distance, MOR and DC of pancreas head after the bony or soft tissue alignment and registration was (7.8 ± 1.3)mm, (87.2 ± 8.4)% and (77.2 ±7.9)% respectively. Compared with the repositioning plan, the ART plan had better target coverage and OARs sparing. For example, the mean V 100 of PTV was improved from (93.32 ± 2.89) % for repositioning plan to (96.03 ± 1.42)% for ART plan with t =2.79, P =0.008 and the mean V 50.4 for duodenum was reduced from (43.4 ± 12.71)% for the repositioning plan to (15.6 ± 6.25)% for the ART plan with t =3.52, P=0.000. Conclusions: The ART can effectively account for the obvious inter-fractional anatomy variations in pancreatic cancer irradiation and be used to escalate the radiotherapy dose for the pancreatic cancer, which will lead to a promising higher local control rate. (authors)

A comparison of kV and MV imaging in head and neck image guided radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Devereux, B. [Radiation Oncology Queensland, 280 North St, Toowoomba 4350 (Australia)], E-mail: beth.devereux@roq.net.au; Frantzis, J.; Sisson, T.; Jones, M.; Martin, J.; Middleton, M. [Radiation Oncology Queensland, 280 North St, Toowoomba 4350 (Australia)

2010-02-15

Purpose: To compare and assess kV and MV imaging modalities and their role in image guided radiotherapy (IGRT) for head and neck cancer patients. Method: Twelve patients receiving radical radiotherapy to the head and neck were analysed in this study. Six patients undertook MV daily online intervention and a further six patients undertook kV daily online intervention. Pre-intervention field placement data were collected from three separate observers' image match analysis for each patient. The radiotherapy collective involved in the daily online image match analysis formed the fourth observer in the study. The primary end point was to establish the difference in inter- and intra-observer variance between kV and MV imaging modalities. Results: The range of the standard deviations of systematic set-up error for MV imaging calculated was 1.47-2.33 mm (MV) and 1.61-1.64 mm (kV) for the right-left (RL), 2.10-2.17 mm (MV) and 1.53-1.84 mm (kV) for the cranio-caudal (CC) and 1.43-1.63 mm (MV) and 1.02-1.11 mm (kV) for the anterior-posterior (AP). The mean inter-observer variance was 0.21 mm (MV) and 0.41 mm (kV) for the RL, 0.53 mm (MV) and 0.55 mm (kV) for the CC and 0.23 mm (MV) and 0.16 mm (kV) for the AP direction. Intra-observer mean variance was in the order of 0.60 mm (MV) and 0.16 mm (kV) for the RL, 1.41 mm (MV) and 0.05 mm (kV) for the CC and 1.41 mm (MV) and 0.08 mm (kV) for the AP. Discussion: The data in this study suggest both inter- and intra-observer consistency across kV and MV imaging modalities were comparable. However, it is felt that the improved clarity and quality of kV imaging allows all observers to analyse images in a consistent manner, identifying and acting on potential field placement moves. Conclusion: The introduction of kV imaging has maintained the high levels of inter- and intra-observer consistency achieved with MV imaging. This in turn further enables positive verification outcomes and supports the implementation of potential

Evaluation of volume change in rectum and bladder during application of image-guided radiotherapy for prostate carcinoma

Energy Technology Data Exchange (ETDEWEB)

Luna, J. A., E-mail: yosimoon13@hotmail.com [Departamento de Física, Universidad Nacional de Costa Rica, Heredia (Costa Rica); Rojas, J. I., E-mail: isaac.rojas@siglo21.cr [Centro Médico Radioterapia Siglo XX1, La Uruca (Costa Rica); PROXTRONICS CR, Ltda, Heredia (Costa Rica)

2016-07-07

All prostate cancer patients from Centro Médico Radioterapia Siglo XXI receive Volumetric Modulated Arc Therapy (VMAT). This therapy uses image-guided radiotherapy (IGRT) with the Cone Beam Computed Tomography (CBCT). This study compares the planned dose in the reference CT image against the delivered dose recalculate in the CBCT image. The purpose of this study is to evaluate the anatomic changes and related dosimetric effect based on weekly CBCT directly for patients with prostate cancer undergoing volumetric modulated arc therapy (VMAT) treatment. The collected data were analyzed using one-way ANOVA.

Constructing a clinical decision-making framework for image-guided radiotherapy using a Bayesian Network

International Nuclear Information System (INIS)

Hargrave, C; Deegan, T; Gibbs, A; Poulsen, M; Moores, M; Harden, F; Mengersen, K

2014-01-01

A decision-making framework for image-guided radiotherapy (IGRT) is being developed using a Bayesian Network (BN) to graphically describe, and probabilistically quantify, the many interacting factors that are involved in this complex clinical process. Outputs of the BN will provide decision-support for radiation therapists to assist them to make correct inferences relating to the likelihood of treatment delivery accuracy for a given image-guided set-up correction. The framework is being developed as a dynamic object-oriented BN, allowing for complex modelling with specific subregions, as well as representation of the sequential decision-making and belief updating associated with IGRT. A prototype graphic structure for the BN was developed by analysing IGRT practices at a local radiotherapy department and incorporating results obtained from a literature review. Clinical stakeholders reviewed the BN to validate its structure. The BN consists of a sub-network for evaluating the accuracy of IGRT practices and technology. The directed acyclic graph (DAG) contains nodes and directional arcs representing the causal relationship between the many interacting factors such as tumour site and its associated critical organs, technology and technique, and inter-user variability. The BN was extended to support on-line and off-line decision-making with respect to treatment plan compliance. Following conceptualisation of the framework, the BN will be quantified. It is anticipated that the finalised decision-making framework will provide a foundation to develop better decision-support strategies and automated correction algorithms for IGRT.

Constructing a clinical decision-making framework for image-guided radiotherapy using a Bayesian Network

Science.gov (United States)

Hargrave, C.; Moores, M.; Deegan, T.; Gibbs, A.; Poulsen, M.; Harden, F.; Mengersen, K.

2014-03-01

A decision-making framework for image-guided radiotherapy (IGRT) is being developed using a Bayesian Network (BN) to graphically describe, and probabilistically quantify, the many interacting factors that are involved in this complex clinical process. Outputs of the BN will provide decision-support for radiation therapists to assist them to make correct inferences relating to the likelihood of treatment delivery accuracy for a given image-guided set-up correction. The framework is being developed as a dynamic object-oriented BN, allowing for complex modelling with specific subregions, as well as representation of the sequential decision-making and belief updating associated with IGRT. A prototype graphic structure for the BN was developed by analysing IGRT practices at a local radiotherapy department and incorporating results obtained from a literature review. Clinical stakeholders reviewed the BN to validate its structure. The BN consists of a sub-network for evaluating the accuracy of IGRT practices and technology. The directed acyclic graph (DAG) contains nodes and directional arcs representing the causal relationship between the many interacting factors such as tumour site and its associated critical organs, technology and technique, and inter-user variability. The BN was extended to support on-line and off-line decision-making with respect to treatment plan compliance. Following conceptualisation of the framework, the BN will be quantified. It is anticipated that the finalised decision-making framework will provide a foundation to develop better decision-support strategies and automated correction algorithms for IGRT.

A Web application for the management of clinical workflow in image-guided and adaptive proton therapy for prostate cancer treatments.

Science.gov (United States)

Yeung, Daniel; Boes, Peter; Ho, Meng Wei; Li, Zuofeng

2015-05-08

Image-guided radiotherapy (IGRT), based on radiopaque markers placed in the prostate gland, was used for proton therapy of prostate patients. Orthogonal X-rays and the IBA Digital Image Positioning System (DIPS) were used for setup correction prior to treatment and were repeated after treatment delivery. Following a rationale for margin estimates similar to that of van Herk,(1) the daily post-treatment DIPS data were analyzed to determine if an adaptive radiotherapy plan was necessary. A Web application using ASP.NET MVC5, Entity Framework, and an SQL database was designed to automate this process. The designed features included state-of-the-art Web technologies, a domain model closely matching the workflow, a database-supporting concurrency and data mining, access to the DIPS database, secured user access and roles management, and graphing and analysis tools. The Model-View-Controller (MVC) paradigm allowed clean domain logic, unit testing, and extensibility. Client-side technologies, such as jQuery, jQuery Plug-ins, and Ajax, were adopted to achieve a rich user environment and fast response. Data models included patients, staff, treatment fields and records, correction vectors, DIPS images, and association logics. Data entry, analysis, workflow logics, and notifications were implemented. The system effectively modeled the clinical workflow and IGRT process.

A technique for adaptive image-guided helical tomotherapy for lung cancer

International Nuclear Information System (INIS)

Ramsey, Chester R.; Langen, Katja M.; Kupelian, Patrick A.; Scaperoth, Daniel D.; Meeks, Sanford L.; Mahan, Stephen L.; Seibert, Rebecca M.

2006-01-01

Purpose: The gross tumor volume (GTV) for many lung cancer patients can decrease during the course of radiation therapy. As the tumor reduces in size during treatment, the margin added around the GTV effectively becomes larger, which can result in the excessive irradiation of normal lung tissue. The specific goal of this study is to evaluate the feasibility of using image-guided adaptive radiation therapy to adjust the planning target volume weekly based on the previous week's CT image sets that were used for image-guided patient setup. Methods and Materials: Megavoltage computed tomography (MVCT) images of the GTV were acquired daily on a helical tomotherapy system. These images were used to position the patient and to measure reduction in GTV volume. A planning study was conducted to determine the amount of lung-sparing that could have been achieved if adaptive therapy had been used. Treatment plans were created in which the target volumes were reduced after tumor reduction was measured. Results: A total of 158 MVCT imaging sessions were performed on 7 lung patients. The GTV was reduced by 60-80% during the course of treatment. The tumor reduction in the first 60 days of treatment can be modeled using the second-order polynomial R 0.0002t 2 - 0.0219t + 1.0, where R is the percent reduction in GTV, and t is the number of elapsed days. Based on these treatment planning studies, the absolute volume of ipsilateral lung receiving 20 Gy can be reduced between 17% and 23% (21% mean) by adapting the treatment delivery. The benefits of adaptive therapy are the greatest for tumor volumes ≥25 cm 3 and are directly dependent on GTV reduction during treatment. Conclusions: Megavoltage CT-based image guidance can be used to position lung cancer patients daily. This has the potential to decrease margins associated with daily setup error. Furthermore, the adaptive therapy technique described in this article can decrease the volume of healthy lung tissue receiving above 20 Gy

Target Coverage in Image-Guided Stereotactic Body Radiotherapy of Liver Tumors

International Nuclear Information System (INIS)

Wunderink, Wouter; Romero, Alejandra Mendez; Osorio, Eliana M. Vasquez; Boer, Hans C.J. de; Brandwijk, Rene P.; Levendag, Peter C.; Heijmen, Ben

2007-01-01

Purpose: To determine the effect of image-guided procedures (with computed tomography [CT] and electronic portal images before each treatment fraction) on target coverage in stereotactic body radiotherapy for liver patients using a stereotactic body frame (SBF) and abdominal compression. CT guidance was used to correct for day-to-day variations in the tumor's mean position in the SBF. Methods and Materials: By retrospectively evaluating 57 treatment sessions, tumor coverage, as obtained with the clinically applied CT-guided protocol, was compared with that of alternative procedures. The internal target volume-plus (ITV + ) was introduced to explicitly include uncertainties in tumor delineations resulting from CT-imaging artifacts caused by residual respiratory motion. Tumor coverage was defined as the volume overlap of the ITV + , derived from a tumor delineated in a treatment CT scan, and the planning target volume. Patient stability in the SBF, after acquisition of the treatment CT scan, was evaluated by measuring the displacement of the bony anatomy in the electronic portal images relative to CT. Results: Application of our clinical protocol (with setup corrections following from manual measurements of the distances between the contours of the planning target volume and the daily clinical target volume in three orthogonal planes, multiple two-dimensional) increased the frequency of nearly full (≥99%) ITV + coverage to 77% compared with 63% without setup correction. An automated three-dimensional method further improved the frequency to 96%. Patient displacements in the SBF were generally small (≤2 mm, 1 standard deviation), but large craniocaudal displacements (maximal 7.2 mm) were occasionally observed. Conclusion: Daily, CT-assisted patient setup may substantially improve tumor coverage, especially with the automated three-dimensional procedure. In the present treatment design, patient stability in the SBF should be verified with portal imaging

SU-E-J-191: Motion Prediction Using Extreme Learning Machine in Image Guided Radiotherapy

International Nuclear Information System (INIS)

Jia, J; Cao, R; Pei, X; Wang, H; Hu, L

2015-01-01

Purpose: Real-time motion tracking is a critical issue in image guided radiotherapy due to the time latency caused by image processing and system response. It is of great necessity to fast and accurately predict the future position of the respiratory motion and the tumor location. Methods: The prediction of respiratory position was done based on the positioning and tracking module in ARTS-IGRT system which was developed by FDS Team (www.fds.org.cn). An approach involving with the extreme learning machine (ELM) was adopted to predict the future respiratory position as well as the tumor’s location by training the past trajectories. For the training process, a feed-forward neural network with one single hidden layer was used for the learning. First, the number of hidden nodes was figured out for the single layered feed forward network (SLFN). Then the input weights and hidden layer biases of the SLFN were randomly assigned to calculate the hidden neuron output matrix. Finally, the predicted movement were obtained by applying the output weights and compared with the actual movement. Breathing movement acquired from the external infrared markers was used to test the prediction accuracy. And the implanted marker movement for the prostate cancer was used to test the implementation of the tumor motion prediction. Results: The accuracy of the predicted motion and the actual motion was tested. Five volunteers with different breathing patterns were tested. The average prediction time was 0.281s. And the standard deviation of prediction accuracy was 0.002 for the respiratory motion and 0.001 for the tumor motion. Conclusion: The extreme learning machine method can provide an accurate and fast prediction of the respiratory motion and the tumor location and therefore can meet the requirements of real-time tumor-tracking in image guided radiotherapy

SU-E-J-191: Motion Prediction Using Extreme Learning Machine in Image Guided Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Jia, J; Cao, R; Pei, X; Wang, H; Hu, L [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); Engineering Technology Research Center of Accurate Radiotherapy of Anhui Province, Hefei 230031 (China); Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, SuZhou (China)

2015-06-15

Purpose: Real-time motion tracking is a critical issue in image guided radiotherapy due to the time latency caused by image processing and system response. It is of great necessity to fast and accurately predict the future position of the respiratory motion and the tumor location. Methods: The prediction of respiratory position was done based on the positioning and tracking module in ARTS-IGRT system which was developed by FDS Team (www.fds.org.cn). An approach involving with the extreme learning machine (ELM) was adopted to predict the future respiratory position as well as the tumor’s location by training the past trajectories. For the training process, a feed-forward neural network with one single hidden layer was used for the learning. First, the number of hidden nodes was figured out for the single layered feed forward network (SLFN). Then the input weights and hidden layer biases of the SLFN were randomly assigned to calculate the hidden neuron output matrix. Finally, the predicted movement were obtained by applying the output weights and compared with the actual movement. Breathing movement acquired from the external infrared markers was used to test the prediction accuracy. And the implanted marker movement for the prostate cancer was used to test the implementation of the tumor motion prediction. Results: The accuracy of the predicted motion and the actual motion was tested. Five volunteers with different breathing patterns were tested. The average prediction time was 0.281s. And the standard deviation of prediction accuracy was 0.002 for the respiratory motion and 0.001 for the tumor motion. Conclusion: The extreme learning machine method can provide an accurate and fast prediction of the respiratory motion and the tumor location and therefore can meet the requirements of real-time tumor-tracking in image guided radiotherapy.

Cone beam computed tomography guided treatment delivery and planning verification for magnetic resonance imaging only radiotherapy of the brain

DEFF Research Database (Denmark)

Edmund, Jens M.; Andreasen, Daniel; Mahmood, Faisal

2015-01-01

CT (CBCT) can be used for MRI-only image-guided radiotherapy (IGRT) and for verifying the correctness of the corresponding pCT. Material and methods. Six patients receiving palliative cranial RT were included in the study. Each patient had three-dimensional (3D) T1W MRI, a CBCT and a CT for reference...

Hybrid adaptive radiotherapy with on-line MRI in cervix cancer IMRT

International Nuclear Information System (INIS)

Oh, Seungjong; Stewart, James; Moseley, Joanne; Kelly, Valerie; Lim, Karen; Xie, Jason; Fyles, Anthony; Brock, Kristy K.; Lundin, Anna; Rehbinder, Henrik; Milosevic, Michael; Jaffray, David

2014-01-01

Purpose: Substantial organ motion and tumor shrinkage occur during radiotherapy for cervix cancer. IMRT planning studies have shown that the quality of radiation delivery is influenced by these anatomical changes, therefore the adaptation of treatment plans may be warranted. Image guidance with off-line replanning, i.e. hybrid-adaptation, is recognized as one of the most practical adaptation strategies. In this study, we investigated the effects of soft tissue image guidance using on-line MR while varying the frequency of off-line replanning on the adaptation of cervix IMRT. Materials and method: 33 cervical cancer patients underwent planning and weekly pelvic MRI scans during radiotherapy. 5 patients of 33 were identified in a previous retrospective adaptive planning study, in which the coverage of gross tumor volume/clinical target volume (GTV/CTV) was not acceptable given single off-line IMRT replan using a 3 mm PTV margin with bone matching. These 5 patients and a randomly selected 10 patients from the remaining 28 patients, a total of 15 patients of 33, were considered in this study. Two matching methods for image guidance (bone to bone and soft tissue to dose matrix) and three frequencies of off-line replanning (none, single, and weekly) were simulated and compared with respect to target coverage (cervix, GTV, lower uterus, parametrium, upper vagina, tumor related CTV and elective lymph node CTV) and OAR sparing (bladder, bowel, rectum, and sigmoid). Cost (total process time) and benefit (target coverage) were analyzed for comparison. Results: Hybrid adaptation (image guidance with off-line replanning) significantly enhanced target coverage for both 5 difficult and 10 standard cases. Concerning image guidance, bone matching was short of delivering enough doses for 5 difficult cases even with a weekly off-line replan. Soft tissue image guidance proved successful for all cases except one when single or more frequent replans were utilized in the difficult cases

Preliminary comparison of the registration effect of 4D-CBCT and 3D-CBCT in image-guided radiotherapy of Stage IA non–small-cell lung cancer

OpenAIRE

Tan, Zhibo; Liu, Chuanyao; Zhou, Ying; Shen, Weixi

2017-01-01

Abstract In this study, we compared the registration effectiveness of 4D cone-beam computed tomography (CBCT) and 3D-CBCT for image-guided radiotherapy in 20 Stage IA non–small-cell lung cancer (NSCLC) patients. Patients underwent 4D-CBCT and 3D-CBCT immediately before radiotherapy, and the X-ray Volume Imaging software system was used for image registration. We performed automatic bone registration and soft tissue registration between 4D-CBCT or 3D-CBCT and 4D-CT images; the regions of inter...

X-ray volume imaging in bladder radiotherapy verification

International Nuclear Information System (INIS)

Henry, Ann M.; Stratford, Julia; McCarthy, Claire; Davies, Julie; Sykes, Jonathan R.; Amer, Ali; Marchant, Tom; Cowan, Richard; Wylie, James; Logue, John; Livsey, Jacqueline; Khoo, Vincent S.; Moore, Chris; Price, Pat

2006-01-01

Purpose: To assess the clinical utility of X-ray volume imaging (XVI) for verification of bladder radiotherapy and to quantify geometric error in bladder radiotherapy delivery. Methods and Materials: Twenty subjects undergoing conformal bladder radiotherapy were recruited. X-ray volume images and electronic portal images (EPIs) were acquired for the first 5 fractions and then once weekly. X-ray volume images were co-registered with the planning computed tomography scan and clinical target volume coverage assessed in three dimensions (3D). Interfraction bladder volume change was described by quantifying changes in bladder volume with time. Bony setup errors were compared from both XVI and EPI. Results: The bladder boundary was clearly visible on coronal XVI views in nearly all images, allowing accurate 3D treatment verification. In 93.5% of imaged fractions, the clinical target volume was within the planning target volume. Most subjects displayed consistent bladder volumes, but 25% displayed changes that could be predicted from the first three XVIs. Bony setup errors were similar whether calculated from XVI or EPI. Conclusions: Coronal XVI can be used to verify 3D bladder radiotherapy delivery. Image-guided interventions to reduce geographic miss and normal tissue toxicity are feasible with this technology

Dose-volume analysis of predictors for chronic rectal toxicity after treatment of prostate cancer with adaptive image-guided radiotherapy

International Nuclear Information System (INIS)

Vargas, Carlos; Martinez, Alvaro; Kestin, Larry L.; Yan Di; Grills, Inga; Brabbins, Donald S.; Lockman, David M.; Liang Jian; Gustafson, Gary S.; Chen, Peter Y.; Vicini, Frank A.; Wong, John W.

2005-01-01

Purpose We analyzed our experience treating localized prostate cancer with image-guided off-line correction with adaptive high-dose radiotherapy (ART) in our Phase II dose escalation study to identify factors predictive of chronic rectal toxicity. Materials and Methods From 1999-2002, 331 patients with clinical stage T1-T3N0M0 prostate cancer were prospectively treated in our Phase II 3D conformal dose escalation ART study to a median dose of 75.6 Gy (range, 63.0-79.2 Gy), minimum dose to confidence limited-planning target volume (cl-PTV) in 1.8 Gy fractions (median isocenter dose = 79.7 Gy). Seventy-four patients (22%) also received neoadjuvant/adjuvant androgen deprivation therapy. A patient-specific cl-PTV was constructed using 5 computed tomography scans and 4 sets of electronic portal images by applying an adaptive process to assure target accuracy and minimize PTV margin. For each case, the rectum (rectal solid) was contoured from the sacroiliac joints or rectosigmoid junction (whichever was higher) to the anal verge or ischial tuberosities (whichever was lower), with a median volume of 81.2 cc. The rectal wall was defined using the rectal solid with an individualized 3-mm wall thickness (median volume = 29.8 cc). Rectal wall dose-volume histogram was used to determine the prescribed dose. Toxicity was quantified using the National Cancer Institute Common Toxicity Criteria 2.0. Multiple dose-volume endpoints were evaluated for their association with chronic rectal toxicity. Results Median follow-up was 1.6 years. Thirty-four patients (crude rate 10.3%) experienced Grade 2 chronic rectal toxicity at a median interval of 1.1 years. Nine patients (crude rate = 2.7%) experienced Grade ≥3 chronic rectal toxicity (1 was Grade 4) at a median interval of 1.2 years. The 3-year rates of Grade ≥2 and Grade ≥3 chronic rectal toxicity were 20% and 4%, respectively. Acute toxicity predicted for chronic: Acute Grade 2-3 rectal toxicity (p 40% respectively. The volume

A quantitative image quality comparison of four different image guided radiotherapy devices

International Nuclear Information System (INIS)

Stuetzel, Julia; Oelfke, Uwe; Nill, Simeon

2008-01-01

Purpose: A study to quantitatively compare the image quality of four different image guided radiotherapy (IGRT) devices based on phantom measurements with respect to the additional dose delivered to the patient. Methods: Images of three different head-sized phantoms (diameter 16-18 cm) were acquired with the following four IGRT-CT solutions: (i) the Siemens Primatom single slice fan beam computed tomography (CT) scanner with an acceleration voltage of 130 kV, (ii) a Tomotherapy HI-ART II unit using a fan beam scanner with an energy of 3.5 MeV and (iii) the Siemens Artiste prototype, providing the possibility to perform kV (121 kV) and MV (6 MV) cone beam (CB) CTs. For each device three scan protocols (named low, normal, high) were selected to yield the same weighted computed tomography dose index (CTDI w ). Based on the individual inserts of the different phantoms the image quality achieved with each device at a certain dose level was characterized in terms of homogeneity, spatial resolution, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and electron density-to-CT-number conversion. Results: Based on the current findings for head-sized phantoms all devices show an electron density-to-CT-number conversion almost independent of the imaging parameters and hence can be suited for treatment planning purposes. The evaluation of the image quality, however, points out clear differences due to the different energies and geometries. The Primatom standard CT scanner shows throughout the best performance, especially for soft tissue contrast and spatial resolution with low imaging doses. Reasonable soft tissue contrast can be obtained with slightly higher doses compared to the CT scanner with the kVCB and the Tomotherapy unit. In order to get similar results with the MVCB system a much higher dose needs to be applied to the patient. Conclusion: Considering the entire investigations, especially in terms of contrast and spatial resolution, a rough tendency for

SU-E-J-181: Magnetic Resonance Image-Guided Radiation Therapy Workflow: Initial Clinical Experience

International Nuclear Information System (INIS)

Green, O; Kashani, R; Santanam, L; Wooten, H; Li, H; Rodriguez, V; Hu, Y; Mutic, S; Hand, T; Victoria, J; Steele, C

2014-01-01

Purpose: The aims of this work are to describe the workflow and initial clinical experience treating patients with an MRI-guided radiotherapy (MRIGRT) system. Methods: Patient treatments with a novel MR-IGRT system started at our institution in mid-January. The system consists of an on-board 0.35-T MRI, with IMRT-capable delivery via doubly-focused MLCs on three 60 Co heads. In addition to volumetric MR-imaging, real-time planar imaging is performed during treatment. So far, eleven patients started treatment (six finished), ranging from bladder to lung SBRT. While the system is capable of online adaptive radiotherapy and gating, a conventional workflow was used to start, consisting of volumetric imaging for patient setup using visible tumor, evaluation of tumor motion outside of PTV on cine images, and real-time imaging. Workflow times were collected and evaluated to increase efficiency and evaluate feasibility of adding the adaptive and gating features while maintaining a reasonable patient throughput. Results: For the first month, physicians attended every fraction to provide guidance on identifying the tumor and an acceptable level of positioning and anatomical deviation. Average total treatment times (including setup) were reduced from 55 to 45 min after physician presence was no longer required and the therapists had learned to align patients based on soft-tissue imaging. Presently, the source strengths were at half maximum (7.7K Ci each), therefore beam-on times will be reduced after source replacement. Current patient load is 10 per day, with increase to 25 anticipated in the near future. Conclusion: On-board, real-time MRI-guided RT has been incorporated into clinical use. Treatment times were kept to reasonable lengths while including volumetric imaging, previews of tumor movement, and physician evaluation. Workflow and timing is being continuously evaluated to increase efficiency. In near future, adaptive and gating capabilities of the system will be

SU-E-J-47: Development of a High-Precision, Image-Guided Radiotherapy, Multi- Purpose Radiation Isocenter Quality-Assurance Calibration and Checking System

International Nuclear Information System (INIS)

Liu, C; Yan, G; Helmig, R; Lebron, S; Kahler, D

2014-01-01

Purpose: To develop a system that can define the radiation isocenter and correlate this information with couch coordinates, laser alignment, optical distance indicator (ODI) settings, optical tracking system (OTS) calibrations, and mechanical isocenter walkout. Methods: Our team developed a multi-adapter, multi-purpose quality assurance (QA) and calibration device that uses an electronic portal imaging device (EPID) and in-house image-processing software to define the radiation isocenter, thereby allowing linear accelerator (Linac) components to be verified and calibrated. Motivated by the concept that each Linac component related to patient setup for image-guided radiotherapy based on cone-beam CT should be calibrated with respect to the radiation isocenter, we designed multiple concentric adapters of various materials and shapes to meet the needs of MV and KV radiation isocenter definition, laser alignment, and OTS calibration. The phantom's ability to accurately define the radiation isocenter was validated on 4 Elekta Linacs using a commercial ball bearing (BB) phantom as a reference. Radiation isocenter walkout and the accuracy of couch coordinates, ODI, and OTS were then quantified with the device. Results: The device was able to define the radiation isocenter within 0.3 mm. Radiation isocenter walkout was within ±1 mm at 4 cardinal angles. By switching adapters, we identified that the accuracy of the couch position digital readout, ODI, OTS, and mechanical isocenter walkout was within sub-mm. Conclusion: This multi-adapter, multi-purpose isocenter phantom can be used to accurately define the radiation isocenter and represents a potential paradigm shift in Linac QA. Moreover, multiple concentric adapters allowed for sub-mm accuracy for the other relevant components. This intuitive and user-friendly design is currently patent pending

Long-term decision regret after post-prostatectomy image-guided intensity-modulated radiotherapy.

Science.gov (United States)

Shakespeare, Thomas P; Chin, Stephen; Manuel, Lucy; Wen, Shelly; Hoffman, Matthew; Wilcox, Shea W; Aherne, Noel J

2017-02-01

Decision regret (DR) may occur when a patient believes their outcome would have been better if they had decided differently about their management. Although some studies investigate DR after treatment for localised prostate cancer, none report DR in patients undergoing surgery and post-prostatectomy radiotherapy. We evaluated DR in this group of patients overall, and for specific components of therapy. We surveyed 83 patients, with minimum 5 years follow-up, treated with radical prostatectomy (RP) and post-prostatectomy image-guided intensity-modulated radiotherapy (IG-IMRT) to 64-66 Gy following www.EviQ.org.au protocols. A validated questionnaire identified DR if men either indicated that they would have been better off had they chosen another treatment, or they wished they could change their mind about treatment. There was an 85.5% response rate, with median follow-up post-IMRT 78 months. Adjuvant IG-IMRT was used in 28% of patients, salvage in 72% and ADT in 48%. A total of 70% of patients remained disease-free. Overall, 16.9% of patients expressed DR for treatment, with fourfold more regret for the RP component of treatment compared to radiotherapy (16.9% vs 4.2%, P = 0.01). DR for androgen deprivation was 14.3%. Patients were regretful of surgery due to toxicity, not being adequately informed about radiotherapy as an alternative, positive margins and surgery costs (83%, 33%, 25% and 8% of regretful patients respectively). Toxicity caused DR in the three radiotherapy-regretful and four ADT-regretful patients. Patients were twice as regretful overall, and of surgery, for salvage vs adjuvant approaches (both 19.6% vs 10.0%). Decision regret after RP and post-prostatectomy IG-IMRT is uncommon, although patients regret RP more than post-operative IG-IMRT. This should reassure urologists referring patients for post-prostatectomy IG-IMRT, particularly in the immediate adjuvant setting. Other implications include appropriate patient selection for RP (and

Integration of PET-CT and cone-beam CT for image-guided radiotherapy with high image quality and registration accuracy

Science.gov (United States)

Wu, T.-H.; Liang, C.-H.; Wu, J.-K.; Lien, C.-Y.; Yang, B.-H.; Huang, Y.-H.; Lee, J. J. S.

2009-07-01

Hybrid positron emission tomography-computed tomography (PET-CT) system enhances better differentiation of tissue uptake of 18F-fluorodeoxyglucose (18F-FDG) and provides much more diagnostic value in the non-small-cell lung cancer and nasopharyngeal carcinoma (NPC). In PET-CT, high quality CT images not only offer diagnostic value on anatomic delineation of the tissues but also shorten the acquisition time for attenuation correction (AC) compared with PET-alone imaging. The linear accelerators equipped with the X-ray cone-beam computed tomography (CBCT) imaging system for image-guided radiotherapy (IGRT) provides excellent verification on position setup error. The purposes of our study were to optimize the CT acquisition protocols of PET-CT and to integrate the PET-CT and CBCT for IGRT. The CT imaging parameters were modified in PET-CT for increasing the image quality in order to enhance the diagnostic value on tumour delineation. Reproducibility and registration accuracy via bone co-registration algorithm between the PET-CT and CBCT were evaluated by using a head phantom to simulate a head and neck treatment condition. Dose measurement in computed tomography dose index (CTDI) was also estimated. Optimization of the CT acquisition protocols of PET-CT was feasible in this study. Co-registration accuracy between CBCT and PET-CT on axial and helical modes was in the range of 1.06 to 2.08 and 0.99 to 2.05 mm, respectively. In our result, it revealed that the accuracy of the co-registration with CBCT on helical mode was more accurate than that on axial mode. Radiation doses in CTDI were 4.76 to 18.5 mGy and 4.83 to 18.79 mGy on axial and helical modes, respectively. Registration between PET-CT and CBCT is a state-of-the-art registration technology which could provide much information on diagnosis and accurate tumour contouring on radiotherapy while implementing radiotherapy procedures. This novelty technology of PET-CT and cone-beam CT integration for IGRT may have a

Integration of PET-CT and cone-beam CT for image-guided radiotherapy with high image quality and registration accuracy

International Nuclear Information System (INIS)

Wu, T-H; Liang, C-H; Wu, J-K; Lien, C-Y; Yang, B-H; Lee, J J S; Huang, Y-H

2009-01-01

Hybrid positron emission tomography-computed tomography (PET-CT) system enhances better differentiation of tissue uptake of 18 F-fluorodeoxyglucose ( 18 F-FDG) and provides much more diagnostic value in the non-small-cell lung cancer and nasopharyngeal carcinoma (NPC). In PET-CT, high quality CT images not only offer diagnostic value on anatomic delineation of the tissues but also shorten the acquisition time for attenuation correction (AC) compared with PET-alone imaging. The linear accelerators equipped with the X-ray cone-beam computed tomography (CBCT) imaging system for image-guided radiotherapy (IGRT) provides excellent verification on position setup error. The purposes of our study were to optimize the CT acquisition protocols of PET-CT and to integrate the PET-CT and CBCT for IGRT. The CT imaging parameters were modified in PET-CT for increasing the image quality in order to enhance the diagnostic value on tumour delineation. Reproducibility and registration accuracy via bone co-registration algorithm between the PET-CT and CBCT were evaluated by using a head phantom to simulate a head and neck treatment condition. Dose measurement in computed tomography dose index (CTDI) was also estimated. Optimization of the CT acquisition protocols of PET-CT was feasible in this study. Co-registration accuracy between CBCT and PET-CT on axial and helical modes was in the range of 1.06 to 2.08 and 0.99 to 2.05 mm, respectively. In our result, it revealed that the accuracy of the co-registration with CBCT on helical mode was more accurate than that on axial mode. Radiation doses in CTDI were 4.76 to 18.5 mGy and 4.83 to 18.79 mGy on axial and helical modes, respectively. Registration between PET-CT and CBCT is a state-of-the-art registration technology which could provide much information on diagnosis and accurate tumour contouring on radiotherapy while implementing radiotherapy procedures. This novelty technology of PET-CT and cone-beam CT integration for IGRT may have a

In-room CT techniques for image-guided radiation therapy

International Nuclear Information System (INIS)

Ma, C.-M. Charlie; Paskalev, Kamen M.S.

2006-01-01

Accurate patient setup and target localization are essential to advanced radiation therapy treatment. Significant improvement has been made recently with the development of image-guided radiation therapy, in which image guidance facilitates short treatment course and high dose per fraction radiotherapy, aiming at improving tumor control and quality of life. Many imaging modalities are being investigated, including x-ray computed tomography (CT), ultrasound imaging, positron emission tomography, magnetic resonant imaging, magnetic resonant spectroscopic imaging, and kV/MV imaging with flat panel detectors. These developments provide unique imaging techniques and methods for patient setup and target localization. Some of them are different; some are complementary. This paper reviews the currently available kV x-ray CT systems used in the radiation treatment room, with a focus on the CT-on-rails systems, which are diagnostic CT scanners moving on rails installed in the treatment room. We will describe the system hardware including configurations, specifications, operation principles, and functionality. We will review software development for image fusion, structure recognition, deformation correction, target localization, and alignment. Issues related to the clinical implementation of in-room CT techniques in routine procedures are discussed, including acceptance testing and quality assurance. Clinical applications of the in-room CT systems for patient setup, target localization, and adaptive therapy are also reviewed for advanced radiotherapy treatments

Adaptive radiotherapy: what to do and to get from it

International Nuclear Information System (INIS)

Di, Y.

2015-01-01

Adaptive radiotherapy individualizes patient treatment by systematically including treatment image feedback in the treatment planning and dose delivering control process. Treatment image feedback can provide information of daily patient treatment position, volume and delivered dose in organs of interest, as well as dose-response-induced bio-activity in tumor and normal tissues. (Author)

[Novel irradiation techniques in the treatment of solid tumours. Radiotherapy for metastases].

Science.gov (United States)

Mayer, Arpád; Póti, Zsuzsa

2014-02-23

Novel developments in percutaneous radiotherapy, such as positron emission tomography/computed tomography, adaptive radiation planning, intensity modulation radiotherapy and intensity modulated arc therapy (RapidArc), as well as the newer generation of image control (cone-beam computed tomography) and image guided radiotherapy ensure increased dosages of planning target volume and clinical target volume of solid tumours without damaging surrounding tissues and providing maximal protection. By raising the dosages of planned target volume and clinical target volume, these novel technical developments have created new indications in the treatment of solid tumours. With the aid of the cone-beam computed tomography and image guided radiotherapy the organ metastasis (lung, liver, spinal cord) and the primary tumour can be treated safety and effectively. Hypofractionation, dose escalation and the use of stereotactic devices can probably decrease radiation damage. The authors review the most common forms of evidence-based fractionation schemes used in irradiation therapy.

Target position uncertainty during visually guided deep-inspiration breath-hold radiotherapy in locally advanced lung cancer

DEFF Research Database (Denmark)

Rydhog, Jonas Scherman; de Blanck, Steen Riisgaard; Josipovic, Mirjana

2017-01-01

Purpose: The purpose of this study was to estimate the uncertainty in voluntary deep-inspiration breath hold (DISH) radiotherapy for locally advanced non-small cell lung cancer (NSCLC) patients.Methods: Perpendicular fluoroscopic movies were acquired in free breathing (FB) and DIBH during a course...... of visually guided DIBH radiotherapy of nine patients with NSCLC. Patients had liquid markers injected in mediastinal lymph nodes and primary tumours. Excursion, systematic- and random errors, and inter-breath-hold position uncertainty were investigated using an image based tracking algorithm.Results: A mean...... small in visually guided breath-hold radiotherapy of NSCLC. Target motion could be substantially reduced, but not eliminated, using visually guided DIBH. (C) 2017 Elsevier B.V. All rights reserved....

SU-F-J-145: MRI-Guided Interventional Boost Radiotherapy for Rectal Cancer: Investigating the Feasibility of Adapting the Anatomy

Energy Technology Data Exchange (ETDEWEB)

Kleijnen, J J E; Couwenberg, A M; Asselen, B van; Lagendijk, J J W; Intven, M; Raaymakers, B W [University Medical Center Utrecht, Utrecht, Utrecht (Netherlands)

2016-06-15

Purpose: The recent development of an MRI-linac allows adaptation of treatments to the anatomy of the moment. This anatomy, in turn, could be altered into a more favorable situation for radiotherapy purposes. The purpose of this study is to investigate the potential dosimetric benefits of manipulating rectal anatomy in MRI-guided interventional external-beam radiotherapy for rectal cancer. Methods: For this retrospective analysis, four patients (1M/3F) diagnosed with rectal cancer were included. These underwent MR-imaging using sonography transmission gel as endorectal contrast at time of diagnosis and standard, non-contrast, MR-imaging prior to radiotherapy planning. In the contrast scan, the rectum is inflated by the inserted contrast gel, thereby potentially increasing the distance between tumor and the organs-at-risk (OAR). Both anatomies were delineated and 7- beam IMRT-plans were calculated for both situations (RT-standard and RT-inflated), using in-house developed treatment planning software. Each plan was aimed to deliver 15Gy to the planning target volume (PTV; tumor+3mm margin) with a D99>95% and Dmax<120% of the planned dose. The D2cc dose to the OAR were then compared for both situations. Results: At equal (or better) target coverage, we found a mean reduction in D2cc of 4.1Gy/237% [range 2.6Gy–6.3Gy/70%–621%] for the bladder and of 2.0Gy/145% [range −0.7Gy–7.9Gy/−73%–442%] for the small-bowel, for the RT-inflated compared to the RT-standard plans. For the three female patients, a reduction in D2cc of 5.2Gy/191% [range 3.2Gy–9.2Gy/44%–475%] for the gynecological organs was found. We found all D2cc doses to be better for the RT-inflated plans, except for one patient for whom the bladder D2cc dose was slightly increased. Conclusion: Reduction of OAR dose by manipulation of anatomy is feasible. Inflation of the rectum results in more distance between OAR and PTV. This leads to a substantial reduction in dose to OAR at equal or better target

Current Brachytherapy Quality Assurance Guidance: Does It Meet the Challenges of Emerging Image-Guided Technologies?

International Nuclear Information System (INIS)

Williamson, Jeffrey F.

2008-01-01

In the past decade, brachytherapy has shifted from the traditional surgical paradigm to more modern three-dimensional image-based planning and delivery approaches. The role of intraoperative and multimodality image-based planning is growing. Published American Association of Physicists in Medicine, American College of Radiology, European Society for Therapeutic Radiology and Oncology, and International Atomic Energy Agency quality assurance (QA) guidelines largely emphasize the QA of planning and delivery devices rather than processes. These protocols have been designed to verify compliance with major performance specifications and are not risk based. With some exceptions, complete and clinically practical guidance exists for sources, QA instrumentation, non-image-based planning systems, applicators, remote afterloading systems, dosimetry, and calibration. Updated guidance is needed for intraoperative imaging systems and image-based planning systems. For non-image-based brachytherapy, the American Association of Physicists in Medicine Task Group reports 56 and 59 provide reasonable guidance on procedure-specific process flow and QA. However, improved guidance is needed even for established procedures such as ultrasound-guided prostate implants. Adaptive replanning in brachytherapy faces unsolved problems similar to that of image-guided adaptive external beam radiotherapy

Prospective phase II study of image-guided local boost using a real-time tumor-tracking radiotherapy (RTRT) system for locally advanced bladder cancer

International Nuclear Information System (INIS)

Nishioka, Kentaro; Shimizu, Shinichi; Shinohara, Nobuo

2014-01-01

The real-time tumor-tracking radiotherapy system with fiducial markers has the advantage that it can be used to verify the localization of the markers during radiation delivery in real-time. We conducted a prospective Phase II study of image-guided local-boost radiotherapy for locally advanced bladder cancer using a real-time tumor-tracking radiotherapy system for positioning, and here we report the results regarding the safety and efficacy of the technique. Twenty patients with a T2-T4N0M0 urothelial carcinoma of the bladder who were clinically inoperable or refused surgery were enrolled. Transurethral tumor resection and 40 Gy irradiation to the whole bladder was followed by the transurethral endoscopic implantation of gold markers in the bladder wall around the primary tumor. A boost of 25 Gy in 10 fractions was made to the primary tumor while maintaining the displacement from the planned position at less than ±2 mm during radiation delivery using a real-time tumor-tracking radiotherapy system. The toxicity, local control and survival were evaluated. Among the 20 patients, 14 were treated with concurrent chemoradiotherapy. The median follow-up period was 55.5 months. Urethral and bowel late toxicity (Grade 3) were each observed in one patient. The local-control rate, overall survival and cause-specific survival with the native bladder after 5 years were 64, 61 and 65%. Image-guided local-boost radiotherapy using a real-time tumor-tracking radiotherapy system can be safely accomplished, and the clinical outcome is encouraging. A larger prospective multi-institutional study is warranted for more precise evaluations of the technological efficacy and patients' quality of life. (author)

Method for automatic re contouring straight adaptive radiotherapy for prostate cancer

International Nuclear Information System (INIS)

Rodriguez Vila, B.; Garcia Vicente, F.; Aguilera, E. J.

2011-01-01

Outline of quickly and accurately the rectal wall is important in Image Guided Radiotherapy (IGRT in the acronym) as an organ of greatest influence in limiting the dose in the planning of radiation therapy in prostate cancer. Deformabies registration methods based on image intensity can not create a correct spatial transformation if there is no correspondence between the image and image planning session. The rectal content variation creates a non-correspondence in the image intensity becomes a major obstacle to the deformable registration based on image intensity.

Knowledge-light adaptation approaches in case-based reasoning for radiotherapy treatment planning.

Science.gov (United States)

Petrovic, Sanja; Khussainova, Gulmira; Jagannathan, Rupa

2016-03-01

Radiotherapy treatment planning aims at delivering a sufficient radiation dose to cancerous tumour cells while sparing healthy organs in the tumour-surrounding area. It is a time-consuming trial-and-error process that requires the expertise of a group of medical experts including oncologists and medical physicists and can take from 2 to 3h to a few days. Our objective is to improve the performance of our previously built case-based reasoning (CBR) system for brain tumour radiotherapy treatment planning. In this system, a treatment plan for a new patient is retrieved from a case base containing patient cases treated in the past and their treatment plans. However, this system does not perform any adaptation, which is needed to account for any difference between the new and retrieved cases. Generally, the adaptation phase is considered to be intrinsically knowledge-intensive and domain-dependent. Therefore, an adaptation often requires a large amount of domain-specific knowledge, which can be difficult to acquire and often is not readily available. In this study, we investigate approaches to adaptation that do not require much domain knowledge, referred to as knowledge-light adaptation. We developed two adaptation approaches: adaptation based on machine-learning tools and adaptation-guided retrieval. They were used to adapt the beam number and beam angles suggested in the retrieved case. Two machine-learning tools, neural networks and naive Bayes classifier, were used in the adaptation to learn how the difference in attribute values between the retrieved and new cases affects the output of these two cases. The adaptation-guided retrieval takes into consideration not only the similarity between the new and retrieved cases, but also how to adapt the retrieved case. The research was carried out in collaboration with medical physicists at the Nottingham University Hospitals NHS Trust, City Hospital Campus, UK. All experiments were performed using real-world brain cancer

Introduction of online adaptive radiotherapy for bladder cancer through a multicentre clinical trial (Trans-Tasman Radiation Oncology Group 10.01): lessons learned

International Nuclear Information System (INIS)

Pham, Daniel; Roxby, Paul; Kron, Tomas; Rolfo, Aldo; Foroudi, Farshad

2013-01-01

Online adaptive radiotherapy for bladder cancer is a novel radiotherapy technique that was found feasible in a pilot study at a single academic institution. In September 2010 this technique was opened as a multicenter study through the Trans-Tasman Radiation Oncology Group (TROG 10.01 bladder online adaptive radiotherapy treatment). Twelve centers across Australia and New-Zealand registered interest into the trial. A multidisciplinary team of radiation oncologists, radiation therapists and medical physicists represented the trial credentialing and technical support team. To provide timely activation and proper implementation of the adaptive technique the following key areas were addressed at each site: Staff education/training; Practical image guided radiotherapy assessment; provision of help desk and feedback. The trial credentialing process involved face-to-face training and technical problem solving via full day site visits. A dedicated 'help-desk' team was developed to provide support for the clinical trial. 26% of the workload occurred at the credentialing period while the remaining 74% came post-center activation. The workload was made up of the following key areas; protocol clarification (36%), technical problems (46%) while staff training was less than 10%. Clinical trial credentialing is important to minimizing trial deviations. It should not only focus on site activation quality assurance but also provide ongoing education and technical support. (author)

Guide for External Beam Radiotherapy. Procedures 2007

International Nuclear Information System (INIS)

Ardiet, Jean-Michel; Bourhis, Jean; Eschwege, Francois; Gerard, Jean-Pierre; Martin, Philippe; Mazeron, Jean-Jacques; Barillot, Isabelle; Bey, Pierre; Cosset, Jean-Marc; Thomas, Olivier; Bolla, Michel; Bourguignon, Michel; Godet, Jean-Luc; Krembel, David; Valero, Marc; Bara, Christine; Beauvais-March, Helene; Derreumaux, Sylvie; Vidal, Jean-Pierre; Drouard, Jean; Sarrazin, Thierry; Lindecker-Cournil, Valerie; Robin, Sun Hee Lee; Thevenet, Nicolas; Depenweiller, Christian; Le Tallec, Philippe; Ortholan, Cecile; Aimone, Nicole; Baldeschi, Carine; Cantelli, Andree; Estivalet, Stephane; Le Prince, Cyrille; QUERO, Laurent; Costa, Andre; Gerard, Jean-Pierre; Ardiet, Jean-Michel; Bensadoun, Rene-Jean; Bourhis, Jean; Calais, Gilles; Lartigau, Eric; Ginot, Aurelie; Girard, Nicolas; Mornex, Francoise; Bolla, Michel; Chauvet, Bruno; Maingon, Philippe; Martin, Etienne; Azria, David; Gerard, Jean-Pierre; Grehange, Gilles; Hennequin, Christophe; Peiffert, Didier; Toledano, Alain; Belkacemi, Yazid; Courdi, Adel; Belliere, Aurelie; Peignaux, Karine; Mahe, Marc; Bondiau, Pierre-Yves; Kantor, Guy; Lepechoux, Cecile; Carrie, Christian; Claude, Line

2007-01-01

In order to optimize quality and security in the delivery of radiation treatment, the French SFRO (Societe francaise de radiotherapie oncologique) is publishing a Guide for Radiotherapy. This guide is realized according to the HAS (Haute Autorite de sante) methodology of 'structured experts consensus'. This document is made of two parts: a general description of external beam radiation therapy and chapters describing the technical procedures of the main tumors to be irradiated (24). For each procedure, a special attention is given to dose constraints in the organs at risk. This guide will be regularly updated

Deep inspiration breath-hold radiotherapy for lung cancer: impact on image quality and registration uncertainty in cone beam CT image guidance

DEFF Research Database (Denmark)

Josipovic, Mirjana; Persson, Gitte F; Bangsgaard, Jens Peter

2016-01-01

OBJECTIVE: We investigated the impact of deep inspiration breath-hold (DIBH) and tumour baseline shifts on image quality and registration uncertainty in image-guided DIBH radiotherapy (RT) for locally advanced lung cancer. METHODS: Patients treated with daily cone beam CT (CBCT)-guided free...

A 3D global-to-local deformable mesh model based registration and anatomy-constrained segmentation method for image guided prostate radiotherapy

International Nuclear Information System (INIS)

Zhou Jinghao; Kim, Sung; Jabbour, Salma; Goyal, Sharad; Haffty, Bruce; Chen, Ting; Levinson, Lydia; Metaxas, Dimitris; Yue, Ning J.

2010-01-01

Purpose: In the external beam radiation treatment of prostate cancers, successful implementation of adaptive radiotherapy and conformal radiation dose delivery is highly dependent on precise and expeditious segmentation and registration of the prostate volume between the simulation and the treatment images. The purpose of this study is to develop a novel, fast, and accurate segmentation and registration method to increase the computational efficiency to meet the restricted clinical treatment time requirement in image guided radiotherapy. Methods: The method developed in this study used soft tissues to capture the transformation between the 3D planning CT (pCT) images and 3D cone-beam CT (CBCT) treatment images. The method incorporated a global-to-local deformable mesh model based registration framework as well as an automatic anatomy-constrained robust active shape model (ACRASM) based segmentation algorithm in the 3D CBCT images. The global registration was based on the mutual information method, and the local registration was to minimize the Euclidian distance of the corresponding nodal points from the global transformation of deformable mesh models, which implicitly used the information of the segmented target volume. The method was applied on six data sets of prostate cancer patients. Target volumes delineated by the same radiation oncologist on the pCT and CBCT were chosen as the benchmarks and were compared to the segmented and registered results. The distance-based and the volume-based estimators were used to quantitatively evaluate the results of segmentation and registration. Results: The ACRASM segmentation algorithm was compared to the original active shape model (ASM) algorithm by evaluating the values of the distance-based estimators. With respect to the corresponding benchmarks, the mean distance ranged from -0.85 to 0.84 mm for ACRASM and from -1.44 to 1.17 mm for ASM. The mean absolute distance ranged from 1.77 to 3.07 mm for ACRASM and from 2.45 to

Integral test phantom for dosimetric quality assurance of image guided and intensity modulated stereotactic radiotherapy.

Science.gov (United States)

Létourneau, Daniel; Keller, Harald; Sharpe, Michael B; Jaffray, David A

2007-05-01

The objective of this work is to develop a dosimetric phantom quality assurance (QA) of linear accelerators capable of cone-beam CT (CBCT) image guided and intensity-modulated radiotherapy (IG-IMRT). This phantom is to be used in an integral test to quantify in real-time both the performance of the image guidance and the dose delivery systems in terms of dose localization. The prototype IG-IMRT QA phantom consisted of a cylindrical imaging phantom (CatPhan) combined with an array of 11 radiation diodes mounted on a 10 cm diameter disk, oriented perpendicular to the phantom axis. Basic diode response characterization was performed for 6 and 18 MV photons. The diode response was compared to planning system calculations in the open and penumbrae regions of simple and complex beam arrangements. The clinical use of the QA phantom was illustrated in an integral test of an IG-IMRT treatment designed for a clinical spinal radiosurgery case. The sensitivity of the phantom to multileaf collimator (MLC) calibration and setup errors in the clinical setting was assessed by introducing errors in the IMRT plan or by displacing the phantom. The diodes offered good response linearity and long-term reproducibility for both 6 and 18 MV. Axial dosimetry of coplanar beams (in a plane containing the beam axes) was made possible with the nearly isoplanatic response of the diodes over 360 degrees of gantry (usually within +/-1%). For single beam geometry, errors in phantom placement as small as 0.5 mm could be accurately detected (in gradient > or = 1% /mm). In clinical setting, MLC systematic errors of 1 mm on a single MLC bank introduced in the IMRT plan were easily detectable with the QA phantom. The QA phantom demonstrated also sufficient sensitivity for the detection of setup errors as small as 1 mm for the IMRT delivery. These results demonstrated that the prototype can accurately and efficiently verify the entire IG-IMRT process. This tool, in conjunction with image guidance

Integral test phantom for dosimetric quality assurance of image guided and intensity modulated stereotactic radiotherapy

International Nuclear Information System (INIS)

Letourneau, Daniel; Keller, Harald; Sharpe, Michael B.; Jaffray, David A.

2007-01-01

The objective of this work is to develop a dosimetric phantom quality assurance (QA) of linear accelerators capable of cone-beam CT (CBCT) image guided and intensity-modulated radiotherapy (IG-IMRT). This phantom is to be used in an integral test to quantify in real-time both the performance of the image guidance and the dose delivery systems in terms of dose localization. The prototype IG-IMRT QA phantom consisted of a cylindrical imaging phantom (CatPhan) combined with an array of 11 radiation diodes mounted on a 10 cm diameter disk, oriented perpendicular to the phantom axis. Basic diode response characterization was performed for 6 and 18 MV photons. The diode response was compared to planning system calculations in the open and penumbrae regions of simple and complex beam arrangements. The clinical use of the QA phantom was illustrated in an integral test of an IG-IMRT treatment designed for a clinical spinal radiosurgery case. The sensitivity of the phantom to multileaf collimator (MLC) calibration and setup errors in the clinical setting was assessed by introducing errors in the IMRT plan or by displacing the phantom. The diodes offered good response linearity and long-term reproducibility for both 6 and 18 MV. Axial dosimetry of coplanar beams (in a plane containing the beam axes) was made possible with the nearly isoplanatic response of the diodes over 360 deg. of gantry (usually within ±1%). For single beam geometry, errors in phantom placement as small as 0.5 mm could be accurately detected (in gradient ≥1%/mm). In clinical setting, MLC systematic errors of 1 mm on a single MLC bank introduced in the IMRT plan were easily detectable with the QA phantom. The QA phantom demonstrated also sufficient sensitivity for the detection of setup errors as small as 1 mm for the IMRT delivery. These results demonstrated that the prototype can accurately and efficiently verify the entire IG-IMRT process. This tool, in conjunction with image guidance capabilities

Intermediate-term results of image-guided brachytherapy and high-technology external beam radiotherapy in cervical cancer: Chiang Mai University experience.

Science.gov (United States)

Tharavichitkul, Ekkasit; Chakrabandhu, Somvilai; Wanwilairat, Somsak; Tippanya, Damrongsak; Nobnop, Wannapha; Pukanhaphan, Nantaka; Galalae, Razvan M; Chitapanarux, Imjai

2013-07-01

To evaluate the outcomes of image-guided brachytherapy combined with 3D conformal or intensity modulated external beam radiotherapy (3D CRT/IMRT) in cervical cancer at Chiang Mai University. From 2008 to 2011, forty-seven patients with locally advanced cervical cancer were enrolled in this study. All patients received high-technology (3D CRT/IMRT) whole pelvic radiotherapy with a total dose of 45-46 Gy plus image-guided High-Dose-Rate intracavitary brachytherapy 6.5-7 Gy × 4 fractions to a High-Risk Clinical Target Volume (HR-CTV) according to GEC-ESTRO recommendations. The dose parameters of the HR-CTV for bladder, rectum and sigmoid colon were recorded, as well as toxicity profiles. In addition, the endpoints for local control, disease-free, metastasis-free survival and overall survival were calculated. At the median follow-up time of 26 months, the local control, disease-free survival, and overall survival rates were 97.9%, 85.1%, and 93.6%, respectively. The mean dose of HR-CTV, bladder, rectum and sigmoid were 93.1, 88.2, 69.6, and 72 Gy, respectively. In terms of late toxicity, the incidence of grade 3-4 bladder and rectum morbidity was 2.1% and 2.1%, respectively. A combination of image-guided brachytherapy and IMRT/3D CRT showed very promising results of local control, disease-free survival, metastasis-free survival and overall survival rates. It also caused a low incidence of grade 3-4 toxicity in treated study patients. Copyright © 2013 Elsevier Inc. All rights reserved.

TU-AB-BRA-11: Indications for Online Adaptive Radiotherapy Based On Dosimetric Consequences of Interfractional Pancreas-To-Duodenum Motion in MRI-Guided Pancreatic Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Mittauer, K; Rosenberg, S; Geurts, M; Bassetti, M; Wojcieszynski, A; Harari, P; Labby, Z; Hill, P; Paliwal, B; Bayouth, J [University of Wisconsin, School of Medicine and Public Health, Madison, WI (United States); Chen, I; Henke, L; Kashani, R; Parikh, P [Washington University School of Medicine, St. Louis, MO (United States); Olsen, J [University of Colorado- Denver, Aurora, CO (United States)

2016-06-15

Purpose: Dose limiting structures, such as the duodenum, render the treatment of pancreatic cancer challenging. In this multi-institutional study, we assess dosimetric differences caused by interfraction pancreas-to-duodenum motion using MR-IGRT to determine the potential impact of adaptive replanning. Methods: Ten patients from two institutions undergoing MRI-guided radiotherapy with conventional fractionation (n=5) or SBRT (n=5) for pancreatic cancer were included. Initial plans were limited by duodenal dose constraints of 50 Gy (0.5 cc)/31 Gy (0.1 cc) for conventional/SBRT with prescriptions of 30 Gy/5 fractions (SBRT) and 40–50 Gy/25 fractions (conventional). Daily volumetric MR images were acquired under treatment conditions on a clinical MR-IGRT system. The correlation was assessed between interfractional GTV-to-duodenum positional variation and daily recalculations of duodenal dose metrics. Positional variation was quantified as the interfraction difference in Hausdorff distance from simulation baseline (ΔHD) between the GTV and proximal duodenal surface, or volume overlap between GTV and duodenum for cases with HD{sub 0}=0 (GTV abutting duodenum). Adaptation was considered indicated when daily positional variations enabled dose escalation to the target while maintaining duodenal constraints. Results: For fractions with ΔHD>0 (n=14, SBRT only), the mean interfraction duodenum dose decrease from simulation to treatment was 44±53 cGy (maximum 136 cGy). A correlation was found between ΔHD and dosimetric difference (R{sup 2}=0.82). No correlation was found between volume of overlap and dosimetric difference (R{sup 2}=0.31). For 89% of fractions, the duodenum remained overlapped with the target and the duodenal dose difference was negligible. The maximum observed indication for adaptation was for interfraction ΔHD=11.6 mm with potential for adaptive dose escalation of 136 cGy. Conclusion: This assessment showed that Hausdorff distance was a reasonable

TU-AB-BRA-11: Indications for Online Adaptive Radiotherapy Based On Dosimetric Consequences of Interfractional Pancreas-To-Duodenum Motion in MRI-Guided Pancreatic Radiotherapy

International Nuclear Information System (INIS)

Mittauer, K; Rosenberg, S; Geurts, M; Bassetti, M; Wojcieszynski, A; Harari, P; Labby, Z; Hill, P; Paliwal, B; Bayouth, J; Chen, I; Henke, L; Kashani, R; Parikh, P; Olsen, J

2016-01-01

Purpose: Dose limiting structures, such as the duodenum, render the treatment of pancreatic cancer challenging. In this multi-institutional study, we assess dosimetric differences caused by interfraction pancreas-to-duodenum motion using MR-IGRT to determine the potential impact of adaptive replanning. Methods: Ten patients from two institutions undergoing MRI-guided radiotherapy with conventional fractionation (n=5) or SBRT (n=5) for pancreatic cancer were included. Initial plans were limited by duodenal dose constraints of 50 Gy (0.5 cc)/31 Gy (0.1 cc) for conventional/SBRT with prescriptions of 30 Gy/5 fractions (SBRT) and 40–50 Gy/25 fractions (conventional). Daily volumetric MR images were acquired under treatment conditions on a clinical MR-IGRT system. The correlation was assessed between interfractional GTV-to-duodenum positional variation and daily recalculations of duodenal dose metrics. Positional variation was quantified as the interfraction difference in Hausdorff distance from simulation baseline (ΔHD) between the GTV and proximal duodenal surface, or volume overlap between GTV and duodenum for cases with HD_0=0 (GTV abutting duodenum). Adaptation was considered indicated when daily positional variations enabled dose escalation to the target while maintaining duodenal constraints. Results: For fractions with ΔHD>0 (n=14, SBRT only), the mean interfraction duodenum dose decrease from simulation to treatment was 44±53 cGy (maximum 136 cGy). A correlation was found between ΔHD and dosimetric difference (R"2=0.82). No correlation was found between volume of overlap and dosimetric difference (R"2=0.31). For 89% of fractions, the duodenum remained overlapped with the target and the duodenal dose difference was negligible. The maximum observed indication for adaptation was for interfraction ΔHD=11.6 mm with potential for adaptive dose escalation of 136 cGy. Conclusion: This assessment showed that Hausdorff distance was a reasonable metric to use to

Image guided radiotherapy with the Cone Beam CT kV (ElektaTM): Experience of the Leon Berard Centre

International Nuclear Information System (INIS)

Pommier, P.; Gassa, F.; Lafay, F.; Claude, L.

2009-01-01

Image guide radiotherapy with the Cone Beam CT kV (C.B.C.T.-kV) developed by Elekta has been implemented at the centre Leon Berard in November 2006. The treatment procedure is presented and detailed for prostate cancer I.G.R.T. and non small cell lung cancer (N.S.C.L.C.) stereotactic radiotherapy (S.R.T.). C.B.C.T.-kV is routinely used for S.R.T., selected paediatric cancers, all prostate carcinomas, primitive brain tumours and head and neck cancers that do not require nodes irradiation. Thirty-five to 40 patients are treated within a daily 11-hours period. The general procedure for 3-dimensional images acquisition and their analysis is described. The C.B.C.T.-kV permitted to identify about 10% of prostate cancer patients for whom a positioning with bone-based 2-dimensional images only would have led to an unacceptable dose distribution for at least one session. S.R.T. is now used routinely for inoperable N.S.C.L.C.. The easiness of implementing C.B.C.T.-kV imaging and its expected medical benefit should lead to a rapid diffusion of this technology that is also submitted to prospective and multi centric medico-economical evaluations. (authors)

Quality assurance in MR image guided adaptive brachytherapy for cervical cancer: Final results of the EMBRACE study dummy run.

Science.gov (United States)

Kirisits, Christian; Federico, Mario; Nkiwane, Karen; Fidarova, Elena; Jürgenliemk-Schulz, Ina; de Leeuw, Astrid; Lindegaard, Jacob; Pötter, Richard; Tanderup, Kari

2015-12-01

Upfront quality assurance (QA) is considered essential when starting a multicenter clinical trial in radiotherapy. Despite the long experience gained for external beam radiotherapy (EBRT) trials, there are only limited audit QA methods for brachytherapy (BT) and none include the specific aspects of image guided adaptive brachytherapy (IGABT). EMBRACE is a prospective multicenter trial aiming to assess the impact of (MRI)-based IGABT in locally advanced cervical cancer. An EMBRACE dummy run was designed to identify sources and magnitude of uncertainties and errors considered important for the evaluation of clinical, and dosimetric parameters and their relation to outcome. Contouring, treatment planning and dose reporting was evaluated and scored with a categorical scale of 1-10. Active feedback to centers was provided to improve protocol compliance and reporting. A second dummy run was required in case of major deviations (score 30 cases) had better performance as compared to centers with limited experience. The comprehensive dummy run designed for the EMBRACE trial has been a feasible tool for QA in IGABT of cervix cancer. It should be considered for future IGABT trials and could serve as the basis for continuous quality checks for brachytherapy centers. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Testicular Doses in Image-Guided Radiotherapy of Prostate Cancer

International Nuclear Information System (INIS)

Deng Jun; Chen Zhe; Yu, James B.; Roberts, Kenneth B.; Peschel, Richard E.; Nath, Ravinder

2012-01-01

Purpose: To investigate testicular doses contributed by kilovoltage cone-beam computed tomography (kVCBCT) during image-guided radiotherapy (IGRT) of prostate cancer. Methods and Materials: An EGS4 Monte Carlo code was used to calculate three-dimensional dose distributions from kVCBCT on 3 prostate cancer patients. Absorbed doses to various organs were compared between intensity-modulated radiotherapy (IMRT) treatments and kVCBCT scans. The impact of CBCT scanning mode, kilovoltage peak energy (kVp), and CBCT field span on dose deposition to testes and other organs was investigated. Results: In comparison with one 10-MV IMRT treatment, a 125-kV half-fan CBCT scan delivered 3.4, 3.8, 4.1, and 5.7 cGy to the prostate, rectum, bladder, and femoral heads, respectively, accounting for 1.7%, 3.2%, 3.2%, and 8.4% of megavoltage photon dose contributions. However, the testes received 2.9 cGy from the same CBCT scan, a threefold increase as compared with 0.7 cGy received during IMRT. With the same kVp, full-fan mode deposited much less dose to organs than half-fan mode, ranging from 9% less for prostate to 69% less for testes, except for rectum, where full-fan mode delivered 34% more dose. As photon beam energy increased from 60 to 125 kV, kVCBCT-contributed doses increased exponentially for all organs, irrespective of scanning mode. Reducing CBCT field span from 30 to 10 cm in the superior–inferior direction cut testicular doses from 5.7 to 0.2 cGy in half-fan mode and from 1.5 to 0.1 cGy in full-fan mode. Conclusions: Compared with IMRT, kVCBCT-contributed doses to the prostate, rectum, bladder, and femoral heads are clinically insignificant, whereas dose to the testes is threefold more. Full-fan CBCT usually deposits much less dose to organs (except for rectum) than half-fan mode in prostate patients. Kilovoltage CBCT–contributed doses increase exponentially with photon beam energy. Reducing CBCT field significantly cuts doses to testes and other organs.

Testicular Doses in Image-Guided Radiotherapy of Prostate Cancer

Energy Technology Data Exchange (ETDEWEB)

Deng Jun, E-mail: jun.deng@yale.edu [Department of Therapeutic Radiology, Yale University, New Haven, CT (United States); Chen Zhe; Yu, James B.; Roberts, Kenneth B.; Peschel, Richard E.; Nath, Ravinder [Department of Therapeutic Radiology, Yale University, New Haven, CT (United States)

2012-01-01

Purpose: To investigate testicular doses contributed by kilovoltage cone-beam computed tomography (kVCBCT) during image-guided radiotherapy (IGRT) of prostate cancer. Methods and Materials: An EGS4 Monte Carlo code was used to calculate three-dimensional dose distributions from kVCBCT on 3 prostate cancer patients. Absorbed doses to various organs were compared between intensity-modulated radiotherapy (IMRT) treatments and kVCBCT scans. The impact of CBCT scanning mode, kilovoltage peak energy (kVp), and CBCT field span on dose deposition to testes and other organs was investigated. Results: In comparison with one 10-MV IMRT treatment, a 125-kV half-fan CBCT scan delivered 3.4, 3.8, 4.1, and 5.7 cGy to the prostate, rectum, bladder, and femoral heads, respectively, accounting for 1.7%, 3.2%, 3.2%, and 8.4% of megavoltage photon dose contributions. However, the testes received 2.9 cGy from the same CBCT scan, a threefold increase as compared with 0.7 cGy received during IMRT. With the same kVp, full-fan mode deposited much less dose to organs than half-fan mode, ranging from 9% less for prostate to 69% less for testes, except for rectum, where full-fan mode delivered 34% more dose. As photon beam energy increased from 60 to 125 kV, kVCBCT-contributed doses increased exponentially for all organs, irrespective of scanning mode. Reducing CBCT field span from 30 to 10 cm in the superior-inferior direction cut testicular doses from 5.7 to 0.2 cGy in half-fan mode and from 1.5 to 0.1 cGy in full-fan mode. Conclusions: Compared with IMRT, kVCBCT-contributed doses to the prostate, rectum, bladder, and femoral heads are clinically insignificant, whereas dose to the testes is threefold more. Full-fan CBCT usually deposits much less dose to organs (except for rectum) than half-fan mode in prostate patients. Kilovoltage CBCT-contributed doses increase exponentially with photon beam energy. Reducing CBCT field significantly cuts doses to testes and other organs.

Risk-adapted targeted intraoperative radiotherapy versus whole-breast radiotherapy for breast cancer

DEFF Research Database (Denmark)

Vaidya, Jayant S; Wenz, Frederik; Bulsara, Max

2014-01-01

The TARGIT-A trial compared risk-adapted radiotherapy using single-dose targeted intraoperative radiotherapy (TARGIT) versus fractionated external beam radiotherapy (EBRT) for breast cancer. We report 5-year results for local recurrence and the first analysis of overall survival....

Image-guided radiotherapy for fifty-eight patients with lung cancer

International Nuclear Information System (INIS)

Liang Jun; Zhang Tao; Wang Wenqin

2009-01-01

Objective: To study the value of image-guided radiotherapy (IGRT) in lung cancer. Methods: From Mar. 2007 to Dec. 2007,58 patients with lung cancer were treated with IGRT. Set-up errors in each axial direction was calculated based on IGRT images of each patient. The change of GTV was evaluated on both cone-beam CT and CT simulator images. Results: Twenty-two patients with left lung cancer,30 with right lung cancer, 5 with mediastinal lymphanode metastasis and one with vertebra metastasis were included. The set-up error in x, y and z axes was (0.02±0.26) cm, (0.14±0.49) cm and ( -0.13± 0.27) cm, respectively,while the rotary set-up error in each axis was -0.15 degree ± 1.59 degree, -0.01 degree ± 1.50 degree and 0.12 degree ±1.08 degree, respectively. The set-up errors were significantly decreased by using of IGRT. GTV movement was observed in 15 patients (25.9%) ,including 5 with left upper lung cancer. GTV moving to the anterior direction was observed in 9 patients,including 4 with]eft upper lung cancer. GTV reduced in 23 (44.2%) patients during treatment. Asymmetric GTV reduction of 22 lesions was observed,with a mean reductive volume of 4.9 cm 3 . When GTV began to shrink,the irradiation dose was 4 -46 Gy, with 20 -30 Gy in 9 patients. Conclusions: The use of IGRT can significantly reduce set-up errors. GTV movement and reduction are observed in some cases. The time to modify the target volume needs to be further studied. (authors)

Toxicity after intensity-modulated, image-guided radiotherapy for prostate cancer

International Nuclear Information System (INIS)

Flentje, Michael; Guckenberger, Matthias; Ok, Sami; Polat, Buelent; Sweeney, Reinhart A.

2010-01-01

Purpose: To evaluate toxicity after dose-escalated radiotherapy for prostate cancer using intensity-modulated treatment planning (IMRT) and image-guided treatment (IGRT) delivery. Patients and Methods: 100 patients were treated with simultaneous integrated boost (SIB) IMRT for prostate cancer: doses of 76.23 Gy and 60 Gy in 33 fractions were prescribed to the prostate and the seminal vesicles, respectively, for intermediate- and high-risk patients (n = 74). The total dose was 73.91 Gy in 32 fractions for low-risk patients and after transurethral resection of the prostate (n = 26). The pelvic lymphatics were treated with 46 Gy in 25 fractions in patients with high risk of lymph node metastases using an SIB to the prostate (n = 25). IGRT was practiced with cone-beam computed tomography. Acute and late gastrointestinal (GI) and genitourinary (GU) toxicity was evaluated prospectively (CTCAE v3.0). Results: Treatment was completed as planned by all patients. Acute GI and GU toxicity grade ≥ 2 was observed in 12% and 42% of the patients, respectively, with 4% suffering from GU toxicity grade 3. 6 weeks after treatment, the incidence of acute toxicity grade ≥ 2 had decreased to 12%. With a median follow-up of 26 months, late GI and GU toxicity grade ≥ 2 was seen in 1.5% and 7.7% of the patients at 24 months. Four patients developed late toxicity grade 3 (GI n = 1; GU n = 3). Presence of acute GI and GU toxicity was significantly associated with late GI (p = 0.0007) and GU toxicity (p = 0.006). Conclusion: High-dose radiotherapy for prostate cancer using IMRT and IGRT resulted in low rates of acute toxicity and preliminary results of late toxicity are promising. (orig.)

Toxicity after intensity-modulated, image-guided radiotherapy for prostate cancer

Energy Technology Data Exchange (ETDEWEB)

Flentje, Michael [Dept. of Radiotherapy, Univ. Hospital Wuerzburg (Germany); Guckenberger, Matthias; Ok, Sami; Polat, Buelent; Sweeney, Reinhart A.

2010-10-15

Purpose: To evaluate toxicity after dose-escalated radiotherapy for prostate cancer using intensity-modulated treatment planning (IMRT) and image-guided treatment (IGRT) delivery. Patients and Methods: 100 patients were treated with simultaneous integrated boost (SIB) IMRT for prostate cancer: doses of 76.23 Gy and 60 Gy in 33 fractions were prescribed to the prostate and the seminal vesicles, respectively, for intermediate- and high-risk patients (n = 74). The total dose was 73.91 Gy in 32 fractions for low-risk patients and after transurethral resection of the prostate (n = 26). The pelvic lymphatics were treated with 46 Gy in 25 fractions in patients with high risk of lymph node metastases using an SIB to the prostate (n = 25). IGRT was practiced with cone-beam computed tomography. Acute and late gastrointestinal (GI) and genitourinary (GU) toxicity was evaluated prospectively (CTCAE v3.0). Results: Treatment was completed as planned by all patients. Acute GI and GU toxicity grade {>=} 2 was observed in 12% and 42% of the patients, respectively, with 4% suffering from GU toxicity grade 3. 6 weeks after treatment, the incidence of acute toxicity grade {>=} 2 had decreased to 12%. With a median follow-up of 26 months, late GI and GU toxicity grade {>=} 2 was seen in 1.5% and 7.7% of the patients at 24 months. Four patients developed late toxicity grade 3 (GI n = 1; GU n = 3). Presence of acute GI and GU toxicity was significantly associated with late GI (p = 0.0007) and GU toxicity (p = 0.006). Conclusion: High-dose radiotherapy for prostate cancer using IMRT and IGRT resulted in low rates of acute toxicity and preliminary results of late toxicity are promising. (orig.)

Functional Image-Guided Radiotherapy Planning in Respiratory-Gated Intensity-Modulated Radiotherapy for Lung Cancer Patients With Chronic Obstructive Pulmonary Disease

Energy Technology Data Exchange (ETDEWEB)

Kimura, Tomoki, E-mail: tkkimura@hiroshima-u.ac.jp [Department of Radiation Oncology, Hiroshima University, Graduate School of Biomedical Sciences, Hiroshima City (Japan); Nishibuchi, Ikuno; Murakami, Yuji; Kenjo, Masahiro; Kaneyasu, Yuko; Nagata, Yasushi [Department of Radiation Oncology, Hiroshima University, Graduate School of Biomedical Sciences, Hiroshima City (Japan)

2012-03-15

Purpose: To investigate the incorporation of functional lung image-derived low attenuation area (LAA) based on four-dimensional computed tomography (4D-CT) into respiratory-gated intensity-modulated radiotherapy (IMRT) or volumetric modulated arc therapy (VMAT) in treatment planning for lung cancer patients with chronic obstructive pulmonary disease (COPD). Methods and Materials: Eight lung cancer patients with COPD were the subjects of this study. LAA was generated from 4D-CT data sets according to CT values of less than than -860 Hounsfield units (HU) as a threshold. The functional lung image was defined as the area where LAA was excluded from the image of the total lung. Two respiratory-gated radiotherapy plans (70 Gy/35 fractions) were designed and compared in each patient as follows: Plan A was an anatomical IMRT or VMAT plan based on the total lung; Plan F was a functional IMRT or VMAT plan based on the functional lung. Dosimetric parameters (percentage of total lung volume irradiated with {>=}20 Gy [V20], and mean dose of total lung [MLD]) of the two plans were compared. Results: V20 was lower in Plan F than in Plan A (mean 1.5%, p = 0.025 in IMRT, mean 1.6%, p = 0.044 in VMAT) achieved by a reduction in MLD (mean 0.23 Gy, p = 0.083 in IMRT, mean 0.5 Gy, p = 0.042 in VMAT). No differences were noted in target volume coverage and organ-at-risk doses. Conclusions: Functional IGRT planning based on LAA in respiratory-guided IMRT or VMAT appears to be effective in preserving a functional lung in lung cancer patients with COPD.

Impact of field number and beam angle on functional image-guided lung cancer radiotherapy planning

Science.gov (United States)

Tahir, Bilal A.; Bragg, Chris M.; Wild, Jim M.; Swinscoe, James A.; Lawless, Sarah E.; Hart, Kerry A.; Hatton, Matthew Q.; Ireland, Rob H.

2017-09-01

To investigate the effect of beam angles and field number on functionally-guided intensity modulated radiotherapy (IMRT) normal lung avoidance treatment plans that incorporate hyperpolarised helium-3 magnetic resonance imaging (3He MRI) ventilation data. Eight non-small cell lung cancer patients had pre-treatment 3He MRI that was registered to inspiration breath-hold radiotherapy planning computed tomography. IMRT plans that minimised the volume of total lung receiving  ⩾20 Gy (V20) were compared with plans that minimised 3He MRI defined functional lung receiving  ⩾20 Gy (fV20). Coplanar IMRT plans using 5-field manually optimised beam angles and 9-field equidistant plans were also evaluated. For each pair of plans, the Wilcoxon signed ranks test was used to compare fV20 and the percentage of planning target volume (PTV) receiving 90% of the prescription dose (PTV90). Incorporation of 3He MRI led to median reductions in fV20 of 1.3% (range: 0.2-9.3% p  =  0.04) and 0.2% (range: 0 to 4.1%; p  =  0.012) for 5- and 9-field arrangements, respectively. There was no clinically significant difference in target coverage. Functionally-guided IMRT plans incorporating hyperpolarised 3He MRI information can reduce the dose received by ventilated lung without comprising PTV coverage. The effect was greater for optimised beam angles rather than uniformly spaced fields.

Reliability of the Bony Anatomy in Image-Guided Stereotactic Radiotherapy of Brain Metastases

International Nuclear Information System (INIS)

Guckenberger, Matthias; Baier, Kurt; Guenther, Iris; Richter, Anne; Wilbert, Juergen; Sauer, Otto; Vordermark, Dirk; Flentje, Michael

2007-01-01

Purpose: To evaluate whether the position of brain metastases remains stable between planning and treatment in cranial stereotactic radiotherapy (SRT). Methods and Materials: Eighteen patients with 20 brain metastases were treated with single-fraction (17 lesions) or hypofractionated (3 lesions) image-guided SRT. Median time interval between planning and treatment was 8 days. Before treatment a cone-beam CT (CBCT) and a conventional CT after application of i.v. contrast were acquired. Setup errors using automatic bone registration (CBCT) and manual soft-tissue registration of the brain metastases (conventional CT) were compared. Results: Tumor size was not significantly different between planning and treatment. The three-dimensional setup error (mean ± SD) was 4.0 ± 2.1 mm and 3.5 ± 2.2 mm according to the bony anatomy and the lesion itself, respectively. A highly significant correlation between automatic bone match and soft-tissue registration was seen in all three directions (r ≥ 0.88). The three-dimensional distance between the isocenter according to bone match and soft-tissue registration was 1.7 ± 0.7 mm, maximum 2.8 mm. Treatment of intracranial pressure with steroids did not influence the position of the lesion relative to the bony anatomy. Conclusion: With a time interval of approximately 1 week between planning and treatment, the bony anatomy of the skull proved to be an excellent surrogate for the target position in image-guided SRT

Introduction of online adaptive radiotherapy for bladder cancer through a multicentre clinical trial (Trans-Tasman Radiation Oncology Group 10.01: Lessons learned

Directory of Open Access Journals (Sweden)

Daniel Pham

2013-01-01

Full Text Available Online adaptive radiotherapy for bladder cancer is a novel radiotherapy technique that was found feasible in a pilot study at a single academic institution. In September 2010 this technique was opened as a multicenter study through the Trans-Tasman Radiation Oncology Group (TROG 10.01 bladder online adaptive radiotherapy treatment. Twelve centers across Australia and New-Zealand registered interest into the trial. A multidisciplinary team of radiation oncologists, radiation therapists and medical physicists represented the trial credentialing and technical support team. To provide timely activation and proper implementation of the adaptive technique the following key areas were addressed at each site: Staff education/training; Practical image guided radiotherapy assessment; provision of help desk and feedback. The trial credentialing process involved face-to-face training and technical problem solving via full day site visits. A dedicated "help-desk" team was developed to provide support for the clinical trial. 26% of the workload occurred at the credentialing period while the remaining 74% came post-center activation. The workload was made up of the following key areas; protocol clarification (36%, technical problems (46% while staff training was less than 10%. Clinical trial credentialing is important to minimizing trial deviations. It should not only focus on site activation quality assurance but also provide ongoing education and technical support.

The influence of the image registration method on the adaptive radiotherapy. A proof of the principle in a selected case of prostate IMRT.

Science.gov (United States)

Berenguer, Roberto; de la Vara, Victoria; Lopez-Honrubia, Veronica; Nuñez, Ana Teresa; Rivera, Miguel; Villas, Maria Victoria; Sabater, Sebastia

2018-01-01

To analyse the influence of the image registration method on the adaptive radiotherapy of an IMRT prostate treatment, and to compare the dose accumulation according to 3 different image registration methods with the planned dose. The IMRT prostate patient was CT imaged 3 times throughout his treatment. The prostate, PTV, rectum and bladder were segmented on each CT. A Rigid, a deformable (DIR) B-spline and a DIR with landmarks registration algorithms were employed. The difference between the accumulated doses and planned doses were evaluated by the gamma index. The Dice coefficient and Hausdorff distance was used to evaluate the overlap between volumes, to quantify the quality of the registration. When comparing adaptive vs no adaptive RT, the gamma index calculation showed large differences depending on the image registration method (as much as 87.6% in the case of DIR B-spline). The quality of the registration was evaluated using an index such as the Dice coefficient. This showed that the best result was obtained with DIR with landmarks compared with the rest and it was always above 0.77, reported as a recommended minimum value for prostate studies in a multi-centre review. Apart from showing the importance of the application of an adaptive RT protocol in a particular treatment, this work shows that the election of the registration method is decisive in the result of the adaptive radiotherapy and dose accumulation. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

SU-E-J-10: Imaging Dose and Cancer Risk in Image-Guided Radiotherapy of Cancers

International Nuclear Information System (INIS)

Zhou, L; Bai, S; Zhang, Y; Deng, J

2015-01-01

Purpose: To systematically evaluate imaging doses and cancer risks to organs-at-risk as a Result of cumulative doses from various radiological imaging procedures in image-guided radiotherapy (IGRT) in a large cohort of cancer patients. Methods: With IRB approval, imaging procedures (computed tomography, kilo-voltage portal imaging, megavoltage portal imaging and kilo-voltage cone-beam computed tomography) of 4832 cancer patients treated during 4.5 years were collected with their gender, age and circumference. Correlations between patient’s circumference and Monte Carlo simulated-organ dose were applied to estimate organ doses while the cancer risks were reported as 1+ERR using BEIR VII models. Results: 80 cGy or more doses were deposited to brain, lungs and RBM in 273 patients (maximum 136, 278 and 267 cGy, respectively), due largely to repetitive imaging procedures and non-personalized imaging settings. Regardless of gender, relative cancer risk estimates for brain, lungs, and RBM were 3.4 (n = 55), 2.6 (n = 49), 1.8 (n = 25) for age group of 0–19; 1.2 (n = 87), 1.4 (n = 98), 1.3 (n = 51) for age group of 20–39; 1.0 (n = 457), 1.1 (n = 880), 1.8 (n=360) for age group of 40–59; 1.0 (n = 646), 1.1 (n = 1400), 2.3 (n = 716) for age group of 60–79 and 1.0 (n = 108),1.1 (n = 305),1.6 (n = 147) for age group of 80–99. Conclusion: The cumulative imaging doses and associated cancer risks from multi-imaging procedures were patient-specific and site-dependent, with up to 2.7 Gy imaging dose deposited to critical structures in some pediatric patients. The associated cancer risks in brain and lungs for children of age 0 to 19 were 2–3 times larger than those for adults. This study indicated a pressing need for personalized imaging protocol to maximize its clinical benefits while reducing associated cancer risks. Sichuan University Scholarship

Remote Cherenkov imaging-based quality assurance of a magnetic resonance image-guided radiotherapy system.

Science.gov (United States)

Andreozzi, Jacqueline M; Mooney, Karen E; Brůža, Petr; Curcuru, Austen; Gladstone, David J; Pogue, Brian W; Green, Olga

2018-06-01

Tools to perform regular quality assurance of magnetic resonance image-guided radiotherapy (MRIgRT) systems should ideally be independent of interference from the magnetic fields. Remotely acquired optical Cherenkov imaging-based dosimetry measurements in water were investigated for this purpose, comparing measures of dose accuracy, temporal dynamics, and overall integrated IMRT delivery. A 40 × 30.5 × 37.5 cm 3 water tank doped with 1 g/L of quinine sulfate was imaged using an intensified charge-coupled device (ICCD) to capture the Cherenkov emission while being irradiated by a commercial MRIgRT system (ViewRay™). The ICCD was placed down-bore at the end of the couch, 4 m from treatment isocenter and behind the 5-Gauss line of the 0.35-T MRI. After establishing optimal camera acquisition settings, square beams of increasing size (4.2 × 4.2 cm 2 , 10.5 × 10.5 cm 2 , and 14.7 × 14.7 cm 2 ) were imaged at 0.93 frames per second, from an individual cobalt-60 treatment head, to develop projection measures related to percent depth dose (PDD) curves and cross beam profiles (CPB). These Cherenkov-derived measurements were compared to ionization chamber (IC) and radiographic film dosimetry data, as well as simulation data from the treatment planning system (TPS). An intensity-modulated radiotherapy (IMRT) commissioning plan from AAPM TG-119 (C4:C-Shape) was also imaged at 2.1 frames per second, and the single linear sum image from 509 s of plan delivery was compared to the dose volume prediction generated by the TPS using gamma index analysis. Analysis of standardized test target images (1024 × 1024 pixels) yielded a pixel resolution of 0.37 mm/pixel. The beam width measured from the Cherenkov image-generated projection CBPs was within 1 mm accuracy when compared to film measurements for all beams. The 502 point measurements (i.e., pixels) of the Cherenkov image-based projection percent depth dose curves (pPDDs) were compared to p

Toward efficient biomechanical-based deformable image registration of lungs for image-guided radiotherapy

Science.gov (United States)

Al-Mayah, Adil; Moseley, Joanne; Velec, Mike; Brock, Kristy

2011-08-01

Both accuracy and efficiency are critical for the implementation of biomechanical model-based deformable registration in clinical practice. The focus of this investigation is to evaluate the potential of improving the efficiency of the deformable image registration of the human lungs without loss of accuracy. Three-dimensional finite element models have been developed using image data of 14 lung cancer patients. Each model consists of two lungs, tumor and external body. Sliding of the lungs inside the chest cavity is modeled using a frictionless surface-based contact model. The effect of the type of element, finite deformation and elasticity on the accuracy and computing time is investigated. Linear and quadrilateral tetrahedral elements are used with linear and nonlinear geometric analysis. Two types of material properties are applied namely: elastic and hyperelastic. The accuracy of each of the four models is examined using a number of anatomical landmarks representing the vessels bifurcation points distributed across the lungs. The registration error is not significantly affected by the element type or linearity of analysis, with an average vector error of around 2.8 mm. The displacement differences between linear and nonlinear analysis methods are calculated for all lungs nodes and a maximum value of 3.6 mm is found in one of the nodes near the entrance of the bronchial tree into the lungs. The 95 percentile of displacement difference ranges between 0.4 and 0.8 mm. However, the time required for the analysis is reduced from 95 min in the quadratic elements nonlinear geometry model to 3.4 min in the linear element linear geometry model. Therefore using linear tetrahedral elements with linear elastic materials and linear geometry is preferable for modeling the breathing motion of lungs for image-guided radiotherapy applications.

WE-EF-BRD-03: I Want It Now!: Advances in MRI Acquisition, Reconstruction and the Use of Priors to Enable Fast Anatomic and Physiologic Imaging to Inform Guidance and Adaptation Decisions

Energy Technology Data Exchange (ETDEWEB)

Hu, Y. [Mayo Clinic Arizona (United States)

2015-06-15

MRI-guided treatment is a growing area of medicine, particularly in radiotherapy and surgery. The exquisite soft tissue anatomic contrast offered by MRI, along with functional imaging, makes the use of MRI during therapeutic procedures very attractive. Challenging the utility of MRI in the therapy room are many issues including the physics of MRI and the impact on the environment and therapeutic instruments, the impact of the room and instruments on the MRI; safety, space, design and cost. In this session, the applications and challenges of MRI-guided treatment will be described. The session format is: Past, present and future: MRI-guided radiotherapy from 2005 to 2025: Jan Lagendijk Battling Maxwell’s equations: Physics challenges and solutions for hybrid MRI systems: Paul Keall I want it now!: Advances in MRI acquisition, reconstruction and the use of priors to enable fast anatomic and physiologic imaging to inform guidance and adaptation decisions: Yanle Hu MR in the OR: The growth and applications of MRI for interventional radiology and surgery: Rebecca Fahrig Learning Objectives: To understand the history and trajectory of MRI-guided radiotherapy To understand the challenges of integrating MR imaging systems with linear accelerators To understand the latest in fast MRI methods to enable the visualisation of anatomy and physiology on radiotherapy treatment timescales To understand the growing role and challenges of MRI for image-guided surgical procedures My disclosures are publicly available and updated at: http://sydney.edu.au/medicine/radiation-physics/about-us/disclosures.php.

Guide of external radiotherapy procedures 2007

International Nuclear Information System (INIS)

Anon.

2008-01-01

This work aims at participating in the permanent optimization of the returned medical service and the ratio profit-risk. This first version of the guide of external radiotherapy procedures 2007 processes only techniques of external radiotherapy, by opposition to the techniques of brachytherapy which use radioactive sources (iridium 192 , iodine 125 , cesium 137 ) placed in the contact of the tumor to be irradiated. Only, also, will be considered the irradiations of the most frequent cunning(malignant) tumors with the exception of the radiotherapy of the mild pathologies and the re-irradiations after a first radiotherapy. The first part is shared in eight chapters as follow: introduction, the steps of a treatment by radiotherapy, infrastructure, equipment and human resources, radiobiology mechanism of action of ionising radiations in radiotherapy, dose in radiotherapy, quality of treatment and radiation protection of patients in radiotherapy, prevention and risk management in radiotherapy, quality assurance and radiation protection for the pediatrics cancers and the case of pregnant women. The second part gives the tumoral localizations and the procedures; the third part is a glossary and different annexes such regulations and legislative texts. (N.C.)

Validation of deformable image registration algorithms on CT images of ex vivo porcine bladders with fiducial markers

NARCIS (Netherlands)

Wognum, S.; Heethuis, S. E.; Rosario, T.; Hoogeman, M. S.; Bel, A.

2014-01-01

The spatial accuracy of deformable image registration (DIR) is important in the implementation of image guided adaptive radiotherapy techniques for cancer in the pelvic region. Validation of algorithms is best performed on phantoms with fiducial markers undergoing controlled large deformations.

Image-guided radiotherapy of bladder cancer: bladder volume variation and its relation to margins

DEFF Research Database (Denmark)

Muren, Ludvig; Redpath, Anthony Thomas; Lord, Hannah

2007-01-01

: The correlation between the relative bladder volume (RBV, defined as repeat scan volume/planning scan volume) and the margins required to account for internal motion was first studied using a series of 20 bladder cancer patients with weekly repeat CT scanning during treatment. Both conformal RT (CRT) and IGRT......BACKGROUND AND PURPOSE: To control and account for bladder motion is a major challenge in radiotherapy (RT) of bladder cancer. This study investigates the relation between bladder volume variation and margins in conformal and image-guided RT (IGRT) for this disease. MATERIALS AND METHODS...... these patients were given fluid intake restrictions on alternating weeks during treatment. RESULTS: IGRT gave the strongest correlation between the RBV and margin size (R(2)=0.75; p10mm were required in only 1% of the situations when the RBV1, whereas isotropic margins >10...

Integration of molecular imaging in treatment planning and delivery of modern radiotherapy

International Nuclear Information System (INIS)

Jacob, V.; Wilkens, J.J.

2011-01-01

Among various imaging modalities currently available, positron emission tomography (PET) has the potential to visualize processes on a molecular level. Molecular imaging, often also referred to as functional or biological imaging, brought a new dimension to diagnostics and therapy of cancer by providing images of metabolism and other processes in the human body and in tumours. PET was first applied for diagnostics and staging of various tumours with high diagnostic precision. Modern radiotherapy asks increasingly for individualized treatment strategies, taking molecular imaging into account. Technical developments over the last years, in particular methods to register various imaging modalities within software packages for treatment planning and target delineation, facilitated the use of PET imaging in radiotherapy. In order to exploit the full potential of modern high-precision radiotherapy, exact imaging procedures are necessary, for example for precise target volume definition. In the long run, concepts employing an inhomogeneous dose prescription based on biological imaging may become routine in clinical applications, leading to individualized, biologically adaptive therapy. (orig.)

On-line MR imaging for dose validation of abdominal radiotherapy

NARCIS (Netherlands)

Glitzner, M; Crijns, S P M; de Senneville, B Denis; Kontaxis, C; Prins, F M; Lagendijk, J J W; Raaymakers, B W

2015-01-01

For quality assurance and adaptive radiotherapy, validation of the actual delivered dose is crucial.Intrafractional anatomy changes cannot be captured satisfactorily during treatment with hitherto available imaging modalitites. Consequently, dose calculations are based on the assumption of static

X-ray volume imaging in image-guided radiotherapy

International Nuclear Information System (INIS)

Thorson, Theodore; Prosser, Tim

2006-01-01

Treatment simulation has significantly improved the accuracy and precision of radiation therapy delivery. A new generation of therapy systems promises to take the simulation and imaging process to a new level of accuracy; however, this will require changes in the workflow process. We describe the first generation of these devices, review the various imaging options and how they might be used in the clinic to improve treatment outcomes, and suggest several workflow approaches. Workflows discussed include on-line interventional, off-line adaptive, and off-line predictive approaches, with both geometric and dosimetric considerations. These changes will place new knowledge requirements on the medical dosimetrist and will necessitate involvement in the development of new departmental processes

Characteristics and performance of a micro-MOSFET: An 'imageable' dosimeter for image-guided radiotherapy

International Nuclear Information System (INIS)

Rowbottom, Carl G.; Jaffray, David A.

2004-01-01

The performance and characteristics of a miniature metal oxide semiconductor field effect transistor (micro-MOSFET) detector was investigated for its potential application to integral system tests for image-guided radiotherapy. In particular, the position of peak response to a slit of radiation was determined for the three principal axes to define the co-ordinates for the center of the active volume of the detector. This was compared to the radiographically determined center of the micro-MOSFET visible using cone-beam CT. Additionally, the angular sensitivity of the micro-MOSFET was measured. The micro-MOSFETs are clearly visible on the cone-beam CT images, and produce no artifacts. The center of the active volume of the micro-MOSFET aligned with the center of the visible micro-MOSFET on the cone-beam CT images for the x and y axes to within 0.20 mm and 0.15 mm, respectively. In z, the long axis of the detector, the peak response was found to be 0.79 mm from the tip of the visible micro-MOSFET. Repeat experiments verified that the position of the peak response of the micro-MOSFET was reproducible. The micro-MOSFET response for 360 deg. of rotation in the axial plane to the micro-MOSFET was ±2%, consistent with values quoted by the manufacturer. The location of the active volume of the micro-MOSFETs under investigation can be determined from the centroid of the visible micro-MOSFET on cone-beam CT images. The CT centroid position corresponds closely to the center of the detector response to radiation. The ability to use the cone-beam CT to locate the active volume to within 0.20 mm allows their use in an integral system test for the imaging of and dose delivery to a phantom containing an array of micro-MOSFETs. The small angular sensitivity allows the investigation of noncoplanar beams

Image-guided intensity-modulated radiotherapy of prostate cancer. Analysis of interfractional errors and acute toxicity

Energy Technology Data Exchange (ETDEWEB)

Rudat, Volker; Nour, A.; Hammoud, M.; Alaradi, A.; Mohammed, A. [Saad Specialist Hospital, Department of Radiation Oncology, Al Khobar (Saudi Arabia)

2016-02-15

The aim of the study was to estimate interfractional deviations in patient and prostate position, the impact of the frequency of online verification on the treatment margins, and to assess acute radiation reactions of high-dose external beam image-guided intensity-modulated radiotherapy (IG-IMRT) of localized prostate cancer. IG-IMRT was performed by daily online verification of implanted fiducial prostate markers using a megavoltage electronic portal imaging device (EPID). A total of 1011 image-guided treatment fractions from 23 consecutive unselected prostate cancer patients were analyzed. The median total dose was 79.2 Gy (range 77.4-81.0 Gy). Acute radiation reactions were assessed weekly during radiotherapy using the Common Terminology Criteria for Adverse Events (CTCAE) v.4.03. A relevant combined patient set-up and prostate motion population random error of 4-5 mm was observed. Compared to daily IGRT, image guidance every other day required an expansion of the CTV-PTV (clinical target volume-planning target volume) margin of 8.1, 6.6, and 4.1 mm in the longitudinal, vertical, and lateral directions, thereby, increasing the PTV by approximately 30-40 %. No grade 3 or 4 acute radiation reactions were observed with daily IG-IMRT. A high dose with surprisingly low acute toxicity can be applied with daily IG-IMRT using implanted fiducial prostate markers. Daily image guidance is clearly superior to image guidance every other fraction concerning adequate target coverage with minimal margins. (orig.) [German] Ziel der Studie war es, die interfraktionelle Variabilitaet der Patientenlagerung und Prostataposition, den Einfluss der Bildgebungsfrequenz und die akuten Strahlenreaktionen bei einer hochdosierten bildgesteuerten intensitaetsmodulierten Strahlentherapie (IG-IMRT) des Prostatakarzinoms zu untersuchen. IG-IMRT wurde durch taegliche Verifikation von implantierten roentgendichten Prostatamarkern mittels Megavolt-Bildgebung (''electronic portal imaging

Image-Guided Hypofractionated Radiotherapy in Low-Risk Prostate Cancer Patients

Directory of Open Access Journals (Sweden)

Maurizio Valeriani

2014-01-01

Full Text Available Aim. To evaluate efficacy and toxicity of image-guided hypofractionated radiotherapy (HFRT in the treatment of low-risk prostate cancer. Outcomes and toxicities of this series of patients were compared to another group of 32 low-risk patients treated with conventional fractionation (CFRT. Methods. Fifty-nine patients with low-risk prostate cancer were analysed. Total dose for the prostate and proximal seminal vesicles was 60 Gy delivered in 20 fractions. Results. The median follow-up was 30 months. The actuarial 4-year overall survival, biochemical free survival, and disease specific survival were 100%, 97.4%, and 97.4%, respectively. Acute grade 1-2 gastrointestinal (GI and genitourinary (GU toxicity rates were 11.9% and 40.7%, respectively. Grade 1 GI and GU late toxicity rates were 8.5% and 13.6%, respectively. No grade ≥2 late toxicities were recorded. Acute grade 2-3 GU toxicity resulted significantly lower (P=0.04 in HFRT group compared to the CFRT group. The cumulative 4-year incidence of grade 1-2 GU toxicity was significantly higher (P<0.001 for HFRT patients. Conclusions. Our study demonstrated that hypofractionated regimen provided excellent biochemical control in favorable risk prostate cancer patients. The incidence of GI and GU toxicity was low. However, HFRT presented higher cumulative incidence of low-grade late GU toxicity than CFRT.

Distortion-free diffusion MRI using an MRI-guided Tri-Cobalt 60 radiotherapy system: Sequence verification and preliminary clinical experience.

Science.gov (United States)

Gao, Yu; Han, Fei; Zhou, Ziwu; Cao, Minsong; Kaprealian, Tania; Kamrava, Mitchell; Wang, Chenyang; Neylon, John; Low, Daniel A; Yang, Yingli; Hu, Peng

2017-10-01

Monitoring tumor response during the course of treatment and adaptively modifying treatment plan based on tumor biological feedback may represent a new paradigm for radiotherapy. Diffusion MRI has shown great promises in assessing and predicting tumor response to radiotherapy. However, the conventional diffusion-weighted single-shot echo-planar-imaging (DW-ssEPI) technique suffers from limited resolution, severe distortion, and possibly inaccurate ADC at low field strength. The purpose of this work was to develop a reliable, accurate and distortion-free diffusion MRI technique that is practicable for longitudinal tumor response evaluation and adaptive radiotherapy on a 0.35 T MRI-guided radiotherapy system. A diffusion-prepared turbo spin echo readout (DP-TSE) sequence was developed and compared with the conventional diffusion-weighted single-shot echo-planar-imaging sequence on a 0.35 T MRI-guided radiotherapy system (ViewRay). A spatial integrity phantom was used to quantitate and compare the geometric accuracy of the two diffusion sequences for three orthogonal orientations. The apparent diffusion coefficient (ADC) accuracy was evaluated on a diffusion phantom under both 0 °C and room temperature to cover a diffusivity range between 0.40 × 10 -3 and 2.10 × 10 -3 mm 2 /s. Ten room temperature measurements repeated on five different days were conducted to assess the ADC reproducibility of DP-TSE. Two glioblastoma (GBM) and six sarcoma patients were included to examine the in vivo feasibility. The target registration error (TRE) was calculated to quantitate the geometric accuracy where structural CT or MR images were co-registered to the diffusion images as references. ADC maps from DP-TSE and DW-ssEPI were calculated and compared. A tube phantom was placed next to patients not treated on ViewRay, and ADCs of this reference tube were also compared. The proposed DP-TSE passed the spatial integrity test (< 1 mm within 100 mm radius and < 2 mm within 175 mm radius

Predicting respiratory motion signals for image-guided radiotherapy using multi-step linear methods (MULIN)

International Nuclear Information System (INIS)

Ernst, Floris; Schweikard, Achim

2008-01-01

Forecasting of respiration motion in image-guided radiotherapy requires algorithms that can accurately and efficiently predict target location. Improved methods for respiratory motion forecasting were developed and tested. MULIN, a new family of prediction algorithms based on linear expansions of the prediction error, was developed and tested. Computer-generated data with a prediction horizon of 150 ms was used for testing in simulation experiments. MULIN was compared to Least Mean Squares-based predictors (LMS; normalized LMS, nLMS; wavelet-based multiscale autoregression, wLMS) and a multi-frequency Extended Kalman Filter (EKF) approach. The in vivo performance of the algorithms was tested on data sets of patients who underwent radiotherapy. The new MULIN methods are highly competitive, outperforming the LMS and the EKF prediction algorithms in real-world settings and performing similarly to optimized nLMS and wLMS prediction algorithms. On simulated, periodic data the MULIN algorithms are outperformed only by the EKF approach due to its inherent advantage in predicting periodic signals. In the presence of noise, the MULIN methods significantly outperform all other algorithms. The MULIN family of algorithms is a feasible tool for the prediction of respiratory motion, performing as well as or better than conventional algorithms while requiring significantly lower computational complexity. The MULIN algorithms are of special importance wherever high-speed prediction is required. (orig.)

Predicting respiratory motion signals for image-guided radiotherapy using multi-step linear methods (MULIN)

Energy Technology Data Exchange (ETDEWEB)

Ernst, Floris; Schweikard, Achim [University of Luebeck, Institute for Robotics and Cognitive Systems, Luebeck (Germany)

2008-06-15

Forecasting of respiration motion in image-guided radiotherapy requires algorithms that can accurately and efficiently predict target location. Improved methods for respiratory motion forecasting were developed and tested. MULIN, a new family of prediction algorithms based on linear expansions of the prediction error, was developed and tested. Computer-generated data with a prediction horizon of 150 ms was used for testing in simulation experiments. MULIN was compared to Least Mean Squares-based predictors (LMS; normalized LMS, nLMS; wavelet-based multiscale autoregression, wLMS) and a multi-frequency Extended Kalman Filter (EKF) approach. The in vivo performance of the algorithms was tested on data sets of patients who underwent radiotherapy. The new MULIN methods are highly competitive, outperforming the LMS and the EKF prediction algorithms in real-world settings and performing similarly to optimized nLMS and wLMS prediction algorithms. On simulated, periodic data the MULIN algorithms are outperformed only by the EKF approach due to its inherent advantage in predicting periodic signals. In the presence of noise, the MULIN methods significantly outperform all other algorithms. The MULIN family of algorithms is a feasible tool for the prediction of respiratory motion, performing as well as or better than conventional algorithms while requiring significantly lower computational complexity. The MULIN algorithms are of special importance wherever high-speed prediction is required. (orig.)

Acute toxicity in prostate cancer patients treated with and without image-guided radiotherapy

Directory of Open Access Journals (Sweden)

Williams Scott

2011-10-01

Full Text Available Abstract Background Image-guided radiotherapy (IGRT increases the accuracy of treatment delivery through daily target localisation. We report on toxicity symptoms experienced during radiotherapy treatment, with and without IGRT in prostate cancer patients treated radically. Methods Between 2006 and 2009, acute toxicity data for ten symptoms were collected prospectively onto standardized assessment forms. Toxicity was scored during radiotherapy, according to the Common Terminology Criteria Adverse Events V3.0, for 275 prostate cancer patients before and after the implementation of a fiducial marker IGRT program and dose escalation from 74Gy in 37 fractions, to 78Gy in 39 fractions. Margins and planning constraints were maintained the same during the study period. The symptoms scored were urinary frequency, cystitis, bladder spasm, urinary incontinence, urinary retention, diarrhoea, haemorrhoids, proctitis, anal skin discomfort and fatigue. Analysis was conducted for the maximum grade of toxicity and the median number of days from the onset of that toxicity to the end of treatment. Results In the IGRT group, 14228 toxicity scores were analysed from 249 patients. In the non-IGRT group, 1893 toxicity scores were analysed from 26 patients. Urinary frequency ≥G3 affected 23% and 7% in the non-IGRT and IGRT group respectively (p = 0.0188. Diarrhoea ≥G2 affected 15% and 3% of patients in the non-IGRT and IGRT groups (p = 0.0174. Fatigue ≥G2 affected 23% and 8% of patients in the non-IGRT and IGRT groups (p = 0.0271. The median number of days with a toxicity was higher for ≥G2 (p = 0.0179 and ≥G3 frequency (p = 0.0027, ≥G2 diarrhoea (p = 0.0033 and ≥G2 fatigue (p = 0.0088 in the non-IGRT group compared to the IGRT group. Other toxicities were not of significant statistical difference. Conclusions In this study, prostate cancer patients treated radically with IGRT had less severe urinary frequency, diarrhoea and fatigue during treatment

Comparison of onboard low-field magnetic resonance imaging versus onboard computed tomography for anatomy visualization in radiotherapy.

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Noel, Camille E; Parikh, Parag J; Spencer, Christopher R; Green, Olga L; Hu, Yanle; Mutic, Sasa; Olsen, Jeffrey R

2015-01-01

Onboard magnetic resonance imaging (OB-MRI) for daily localization and adaptive radiotherapy has been under development by several groups. However, no clinical studies have evaluated whether OB-MRI improves visualization of the target and organs at risk (OARs) compared to standard onboard computed tomography (OB-CT). This study compared visualization of patient anatomy on images acquired on the MRI-(60)Co ViewRay system to those acquired with OB-CT. Fourteen patients enrolled on a protocol approved by the Institutional Review Board (IRB) and undergoing image-guided radiotherapy for cancer in the thorax (n = 2), pelvis (n = 6), abdomen (n = 3) or head and neck (n = 3) were imaged with OB-MRI and OB-CT. For each of the 14 patients, the OB-MRI and OB-CT datasets were displayed side-by-side and independently reviewed by three radiation oncologists. Each physician was asked to evaluate which dataset offered better visualization of the target and OARs. A quantitative contouring study was performed on two abdominal patients to assess if OB-MRI could offer improved inter-observer segmentation agreement for adaptive planning. In total 221 OARs and 10 targets were compared for visualization on OB-MRI and OB-CT by each of the three physicians. The majority of physicians (two or more) evaluated visualization on MRI as better for 71% of structures, worse for 10% of structures, and equivalent for 14% of structures. 5% of structures were not visible on either. Physicians agreed unanimously for 74% and in majority for > 99% of structures. Targets were better visualized on MRI in 4/10 cases, and never on OB-CT. Low-field MR provides better anatomic visualization of many radiotherapy targets and most OARs as compared to OB-CT. Further studies with OB-MRI should be pursued.

SU-E-J-153: MRI Based, Daily Adaptive Radiotherapy for Rectal Cancer: Contour Adaptation

International Nuclear Information System (INIS)

Kleijnen, J; Burbach, M; Verbraeken, T; Weggers, R; Zoetelief, A; Reerink, O; Lagendijk, J; Raaymakers, B; Asselen, B

2014-01-01

Purpose: A major hurdle in adaptive radiotherapy is the adaptation of the planning MRI's delineations to the daily anatomy. We therefore investigate the accuracy and time needed for online clinical target volume (CTV) adaptation by radiation therapists (RTT), to be used in MRI-guided adaptive treatments on a MRI-Linac (MRL). Methods: Sixteen patients, diagnosed with early stage rectal cancer, underwent a T2-weighted MRI prior to each fraction of short-course radiotherapy, resulting in 4–5 scans per patient. On these scans, the CTV was delineated according to guidelines by an experienced radiation oncologist (RO) and considered to be the gold standard. For each patient, the first MRI was considered as the planning MRI and matched on bony anatomy to the 3–4 daily MRIs. The planning MRI's CTV delineation was rigidly propagated to the daily MRI scans as a proposal for adaptation. Three RTTs in training started the adaptation of the CTV conform guidelines, after a two hour training lecture and a two patient (n=7) training set. To assess the inter-therapist variation, all three RTTs altered delineations of 3 patients (n=12). One RTT altered the CTV delineations (n=53) of the remaining 11 patients. Time needed for adaptation of the CTV to guidelines was registered.As a measure of agreement, the conformity index (CI) was determined between the RTTs' delineations as a group. Dice similarity coefficients were determined between delineations of the RTT and the RO. Results: We found good agreement between RTTs' and RO's delineations (average Dice=0.91, SD=0.03). Furthermore, the inter-observer agreement between the RTTs was high (average CI=0.94, SD=0.02). Adaptation time reduced from 10:33 min (SD= 3:46) to 2:56 min (SD=1:06) between the first and last ten delineations, respectively. Conclusion: Daily CTV adaptation by RTTs, seems a feasible and safe way to introduce daily, online MRI-based plan adaptation for a MRL

Learning statistical correlation for fast prostate registration in image-guided radiotherapy

International Nuclear Information System (INIS)

Shi Yonghong; Liao Shu; Shen Dinggang

2011-01-01

Purpose: In adaptive radiation therapy of prostate cancer, fast and accurate registration between the planning image and treatment images of the patient is of essential importance. With the authors' recently developed deformable surface model, prostate boundaries in each treatment image can be rapidly segmented and their correspondences (or relative deformations) to the prostate boundaries in the planning image are also established automatically. However, the dense correspondences on the nonboundary regions, which are important especially for transforming the treatment plan designed in the planning image space to each treatment image space, are remained unresolved. This paper presents a novel approach to learn the statistical correlation between deformations of prostate boundary and nonboundary regions, for rapidly estimating deformations of the nonboundary regions when given the deformations of the prostate boundary at a new treatment image. Methods: The main contributions of the proposed method lie in the following aspects. First, the statistical deformation correlation will be learned from both current patient and other training patients, and further updated adaptively during the radiotherapy. Specifically, in the initial treatment stage when the number of treatment images collected from the current patient is small, the statistical deformation correlation is mainly learned from other training patients. As more treatment images are collected from the current patient, the patient-specific information will play a more important role in learning patient-specific statistical deformation correlation to effectively reflect prostate deformation of the current patient during the treatment. Eventually, only the patient-specific statistical deformation correlation is used to estimate dense correspondences when a sufficient number of treatment images have been acquired from the current patient. Second, the statistical deformation correlation will be learned by using a

A hybrid strategy of offline adaptive planning and online image guidance for prostate cancer radiotherapy

International Nuclear Information System (INIS)

Lei Yu; Wu Qiuwen

2010-01-01

Offline adaptive radiotherapy (ART) has been used to effectively correct and compensate for prostate motion and reduce the required margin. The efficacy depends on the characteristics of the patient setup error and interfraction motion through the whole treatment; specifically, systematic errors are corrected and random errors are compensated for through the margins. In online image-guided radiation therapy (IGRT) of prostate cancer, the translational setup error and inter-fractional prostate motion are corrected through pre-treatment imaging and couch correction at each fraction. However, the rotation and deformation of the target are not corrected and only accounted for with margins in treatment planning. The purpose of this study was to investigate whether the offline ART strategy is necessary for an online IGRT protocol and to evaluate the benefit of the hybrid strategy. First, to investigate the rationale of the hybrid strategy, 592 cone-beam-computed tomography (CBCT) images taken before and after each fraction for an online IGRT protocol from 16 patients were analyzed. Specifically, the characteristics of prostate rotation were analyzed. It was found that there exist systematic inter-fractional prostate rotations, and they are patient specific. These rotations, if not corrected, are persistent through the treatment fraction, and rotations detected in early fractions are representative of those in later fractions. These findings suggest that the offline adaptive replanning strategy is beneficial to the online IGRT protocol with further margin reductions. Second, to quantitatively evaluate the benefit of the hybrid strategy, 412 repeated helical CT scans from 25 patients during the course of treatment were included in the replanning study. Both low-risk patients (LRP, clinical target volume, CTV = prostate) and intermediate-risk patients (IRP, CTV = prostate + seminal vesicles) were included in the simulation. The contours of prostate and seminal vesicles were

Implementation of an image guided intensity-modulated protocol for post-prostatectomy radiotherapy: planning data and acute toxicity outcomes.

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Chua, Benjamin; Min, Myo; Wood, Maree; Edwards, Sarah; Hoffmann, Matthew; Greenham, Stuart; Kovendy, Andrew; McKay, Michael J; Shakespeare, Thomas P

2013-08-01

There is substantial interest in implementation of image-guided intensity-modulated radiotherapy (IG-IMRT) in the post-prostatectomy setting. We describe our implementation of IG-IMRT, and examine how often published organ-at-risk (OAR) constraints were met. Furthermore, we evaluate the incidence of acute genitourinary and gastrointestinal toxicities when patients were treated according to our protocol. Patients were eligible if they received post-prostatectomy radiotherapy (PPRT). Planning data were collected prospectively, and toxicity assessments were collected before, during and after treatment. Seventy-five eligible patients received either 64 Gy (19%) or 66 Gy (81%) in a single phase to the prostate bed. Suggested rectal dose-constraints of V40Gy < 60% and V60Gy < 40% were met in 64 (85%) and 75 (100%) patients, respectively. IMRT-specific rectal dose-constraints of V40Gy < 35% and V65Gy < 17% were achieved in 5 (7%) and 57 (76%) of patients. Bladder dose-constraint (V50Gy < 50%) was met in 58 (77%) patients. Two patients (3%) experienced new grade 3 genitourinary toxicity and one patient (1%) experienced new grade 3 gastroinestinal toxicity. All grade 3 toxicities had improved by 3-month review. Overall deterioration in urinary and gastrointestinal symptoms occurred in 33 (44%) and 35 (47%) of patients respectively. We report on our implementation of PPRT which takes into account nationally adopted guidelines, with a margin reduction supported by use of daily image guidance. Non-IMRT OAR constraints were met in most cases. IMRT-specific constraints were less often achieved despite margin reductions, suggesting the need for review of guidelines. Severe toxicity was rare, and most patients did not experience deterioration in urinary or bowel function attributable to radiotherapy. © 2013 The Authors. Journal of Medical Imaging and Radiation Oncology © 2013 The Royal Australian and New Zealand College of Radiologists.

[The need for a paradigm shift in radiotherapy].

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Mayer, Árpád; Katona, Csilla; Farkas, Róbert; Póti, Zsuzsa

2015-11-01

The status and indications of radiotherapy have significantly changed in the past decade because novel techniques, radiobiological research and major advances in informatics have made better local control possible. Using supplemented marking of the target volume with computer tomography based other image-making methods adapted made it possible to define the tumor and intact surrounding tissues more precisely. With novel radiotherapy techniques the dosage of the homogenity and the covering in the target volume can be raised optimally, especially with intensity modulated arc radiotherapy (volumetric modulated arc therapy) without causing radiation injury or damage to intact surrounding tissues. Furthermore, with novel techniques and target volume marking, new indications have appeared in clinical practice and besides stereotactic radiotherapy for intracranial metastases, the extracranial so-called oligometastic conditions can be maintained close to a curative state (or in remission) for many years. Among these, perhaps the most striking is the stereotactic radiotherapy treatment of liver, lung and spinal cord metastases in one or more fractions, for which the indispensable condition is the image or respiratory guided technique.

Adapting radiotherapy to hypoxic tumours

International Nuclear Information System (INIS)

Malinen, Eirik; Soevik, Aste; Hristov, Dimitre; Bruland, Oeyvind S; Olsen, Dag Rune

2006-01-01

In the current work, the concepts of biologically adapted radiotherapy of hypoxic tumours in a framework encompassing functional tumour imaging, tumour control predictions, inverse treatment planning and intensity modulated radiotherapy (IMRT) were presented. Dynamic contrast enhanced magnetic resonance imaging (DCEMRI) of a spontaneous sarcoma in the nasal region of a dog was employed. The tracer concentration in the tumour was assumed related to the oxygen tension and compared to Eppendorf histograph measurements. Based on the pO 2 -related images derived from the MR analysis, the tumour was divided into four compartments by a segmentation procedure. DICOM structure sets for IMRT planning could be derived thereof. In order to display the possible advantages of non-uniform tumour doses, dose redistribution among the four tumour compartments was introduced. The dose redistribution was constrained by keeping the average dose to the tumour equal to a conventional target dose. The compartmental doses yielding optimum tumour control probability (TCP) were used as input in an inverse planning system, where the planning basis was the pO 2 -related tumour images from the MR analysis. Uniform (conventional) and non-uniform IMRT plans were scored both physically and biologically. The consequences of random and systematic errors in the compartmental images were evaluated. The normalized frequency distributions of the tracer concentration and the pO 2 Eppendorf measurements were not significantly different. 28% of the tumour had, according to the MR analysis, pO 2 values of less than 5 mm Hg. The optimum TCP following a non-uniform dose prescription was about four times higher than that following a uniform dose prescription. The non-uniform IMRT dose distribution resulting from the inverse planning gave a three times higher TCP than that of the uniform distribution. The TCP and the dose-based plan quality depended on IMRT parameters defined in the inverse planning procedure

Adapting radiotherapy to hypoxic tumours

Science.gov (United States)

Malinen, Eirik; Søvik, Åste; Hristov, Dimitre; Bruland, Øyvind S.; Rune Olsen, Dag

2006-10-01

In the current work, the concepts of biologically adapted radiotherapy of hypoxic tumours in a framework encompassing functional tumour imaging, tumour control predictions, inverse treatment planning and intensity modulated radiotherapy (IMRT) were presented. Dynamic contrast enhanced magnetic resonance imaging (DCEMRI) of a spontaneous sarcoma in the nasal region of a dog was employed. The tracer concentration in the tumour was assumed related to the oxygen tension and compared to Eppendorf histograph measurements. Based on the pO2-related images derived from the MR analysis, the tumour was divided into four compartments by a segmentation procedure. DICOM structure sets for IMRT planning could be derived thereof. In order to display the possible advantages of non-uniform tumour doses, dose redistribution among the four tumour compartments was introduced. The dose redistribution was constrained by keeping the average dose to the tumour equal to a conventional target dose. The compartmental doses yielding optimum tumour control probability (TCP) were used as input in an inverse planning system, where the planning basis was the pO2-related tumour images from the MR analysis. Uniform (conventional) and non-uniform IMRT plans were scored both physically and biologically. The consequences of random and systematic errors in the compartmental images were evaluated. The normalized frequency distributions of the tracer concentration and the pO2 Eppendorf measurements were not significantly different. 28% of the tumour had, according to the MR analysis, pO2 values of less than 5 mm Hg. The optimum TCP following a non-uniform dose prescription was about four times higher than that following a uniform dose prescription. The non-uniform IMRT dose distribution resulting from the inverse planning gave a three times higher TCP than that of the uniform distribution. The TCP and the dose-based plan quality depended on IMRT parameters defined in the inverse planning procedure (fields

Online Magnetic Resonance Image Guided Adaptive Radiation Therapy: First Clinical Applications

International Nuclear Information System (INIS)

Acharya, Sahaja; Fischer-Valuck, Benjamin W.; Kashani, Rojano; Parikh, Parag; Yang, Deshan; Zhao, Tianyu; Green, Olga; Wooten, Omar; Li, H. Harold; Hu, Yanle; Rodriguez, Vivian; Olsen, Lindsey; Robinson, Clifford; Michalski, Jeff; Mutic, Sasa; Olsen, Jeffrey

2016-01-01

Purpose: To demonstrate the feasibility of online adaptive magnetic resonance (MR) image guided radiation therapy (MR-IGRT) through reporting of our initial clinical experience and workflow considerations. Methods and Materials: The first clinically deployed online adaptive MR-IGRT system consisted of a split 0.35T MR scanner straddling a ring gantry with 3 multileaf collimator-equipped "6"0Co heads. The unit is supported by a Monte Carlo–based treatment planning system that allows real-time adaptive planning with the patient on the table. All patients undergo computed tomography and MR imaging (MRI) simulation for initial treatment planning. A volumetric MRI scan is acquired for each patient at the daily treatment setup. Deformable registration is performed using the planning computed tomography data set, which allows for the transfer of the initial contours and the electron density map to the daily MRI scan. The deformed electron density map is then used to recalculate the original plan on the daily MRI scan for physician evaluation. Recontouring and plan reoptimization are performed when required, and patient-specific quality assurance (QA) is performed using an independent in-house software system. Results: The first online adaptive MR-IGRT treatments consisted of 5 patients with abdominopelvic malignancies. The clinical setting included neoadjuvant colorectal (n=3), unresectable gastric (n=1), and unresectable pheochromocytoma (n=1). Recontouring and reoptimization were deemed necessary for 3 of 5 patients, and the initial plan was deemed sufficient for 2 of the 5 patients. The reasons for plan adaptation included tumor progression or regression and a change in small bowel anatomy. In a subsequently expanded cohort of 170 fractions (20 patients), 52 fractions (30.6%) were reoptimized online, and 92 fractions (54.1%) were treated with an online-adapted or previously adapted plan. The median time for recontouring, reoptimization, and QA was 26�

Online Magnetic Resonance Image Guided Adaptive Radiation Therapy: First Clinical Applications

Energy Technology Data Exchange (ETDEWEB)

Acharya, Sahaja; Fischer-Valuck, Benjamin W.; Kashani, Rojano; Parikh, Parag; Yang, Deshan; Zhao, Tianyu; Green, Olga; Wooten, Omar; Li, H. Harold; Hu, Yanle; Rodriguez, Vivian; Olsen, Lindsey; Robinson, Clifford; Michalski, Jeff; Mutic, Sasa; Olsen, Jeffrey, E-mail: jolsen@radonc.wustl.edu

2016-02-01

Purpose: To demonstrate the feasibility of online adaptive magnetic resonance (MR) image guided radiation therapy (MR-IGRT) through reporting of our initial clinical experience and workflow considerations. Methods and Materials: The first clinically deployed online adaptive MR-IGRT system consisted of a split 0.35T MR scanner straddling a ring gantry with 3 multileaf collimator-equipped {sup 60}Co heads. The unit is supported by a Monte Carlo–based treatment planning system that allows real-time adaptive planning with the patient on the table. All patients undergo computed tomography and MR imaging (MRI) simulation for initial treatment planning. A volumetric MRI scan is acquired for each patient at the daily treatment setup. Deformable registration is performed using the planning computed tomography data set, which allows for the transfer of the initial contours and the electron density map to the daily MRI scan. The deformed electron density map is then used to recalculate the original plan on the daily MRI scan for physician evaluation. Recontouring and plan reoptimization are performed when required, and patient-specific quality assurance (QA) is performed using an independent in-house software system. Results: The first online adaptive MR-IGRT treatments consisted of 5 patients with abdominopelvic malignancies. The clinical setting included neoadjuvant colorectal (n=3), unresectable gastric (n=1), and unresectable pheochromocytoma (n=1). Recontouring and reoptimization were deemed necessary for 3 of 5 patients, and the initial plan was deemed sufficient for 2 of the 5 patients. The reasons for plan adaptation included tumor progression or regression and a change in small bowel anatomy. In a subsequently expanded cohort of 170 fractions (20 patients), 52 fractions (30.6%) were reoptimized online, and 92 fractions (54.1%) were treated with an online-adapted or previously adapted plan. The median time for recontouring, reoptimization, and QA was 26�

Magnetic resonance imaging for assessment of parametrial tumour spread and regression patterns in adaptive cervix cancer radiotherapy

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Schmid, Maximilian P.; Fidarova, Elena [Dept. of Radiotherapy, Comprehensive Cancer Center, Medical Univ. of Vienna, Vienna (Austria)], e-mail: maximilian.schmid@akhwien.at; Poetter, Richard [Dept. of Radiotherapy, Comprehensive Cancer Center, Medical Univ. of Vienna, Vienna (Austria); Christian Doppler Lab. for Medical Radiation Research for Radiation Oncology, Medical Univ. of Vienna (Austria)] [and others

2013-10-15

Purpose: To investigate the impact of magnetic resonance imaging (MRI)-morphologic differences in parametrial infiltration on tumour response during primary radio chemotherapy in cervical cancer. Material and methods: Eighty-five consecutive cervical cancer patients with FIGO stages IIB (n = 59) and IIIB (n = 26), treated by external beam radiotherapy ({+-}chemotherapy) and image-guided adaptive brachytherapy, underwent T2-weighted MRI at the time of diagnosis and at the time of brachytherapy. MRI patterns of parametrial tumour infiltration at the time of diagnosis were assessed with regard to predominant morphology and maximum extent of parametrial tumour infiltration and were stratified into five tumour groups (TG): 1) expansive with spiculae; 2) expansive with spiculae and infiltrating parts; 3) infiltrative into the inner third of the parametrial space (PM); 4) infiltrative into the middle third of the PM; and 5) infiltrative into the outer third of the PM. MRI at the time of brachytherapy was used for identifying presence (residual vs. no residual disease) and signal intensity (high vs. intermediate) of residual disease within the PM. Left and right PM of each patient were evaluated separately at both time points. The impact of the TG on tumour remission status within the PM was analysed using {chi}2-test and logistic regression analysis. Results: In total, 170 PM were analysed. The TG 1, 2, 3, 4, 5 were present in 12%, 11%, 35%, 25% and 12% of the cases, respectively. Five percent of the PM were tumour-free. Residual tumour in the PM was identified in 19%, 68%, 88%, 90% and 85% of the PM for the TG 1, 2, 3, 4, and 5, respectively. The TG 3 - 5 had significantly higher rates of residual tumour in the PM in comparison to TG 1 + 2 (88% vs. 43%, p < 0.01). Conclusion: MRI-morphologic features of PM infiltration appear to allow for prediction of tumour response during external beam radiotherapy and chemotherapy. A predominantly infiltrative tumour spread at the

Patient dose in image guided radiotherapy: Monte Carlo study of the CBCT dose contribution

Directory of Open Access Journals (Sweden)

Salvatore Leotta

2018-02-01

Full Text Available Image Guided RadioTherapy (IGRT is a technique whose diffusion is growing thanks to the well-recognized gain in accuracy of dose delivery. However, multiple Cone Beam Computed Tomography (CBCT scans add dose to patients, and its contribution has to be assessed and minimized. Aim of our work was to evaluate, through Monte Carlo simulations, organ doses in IGRT due to CBCT and therapeutic MV irradiation in head-neck, thorax and pelvis districts. We developed a Monte Carlo simulation in GAMOS (Geant4-based Architecture for Medicine-Oriented Simulations, reproducing an Elekta Synergy medical linac operating at 6 and 10 MV photon energy, and we set up a scalable anthropomorphic model. After a validation by comparison with the experimental quality indexes, we evaluated the average doses to all organs and tissues belonging to the model for the three cases of irradiated district. Scattered radiation in therapy is larger than that diffused by CBCT by one to two orders of magnitude.

Deformable registration of the planning image (kVCT) and the daily images (MVCT) for adaptive radiation therapy

International Nuclear Information System (INIS)

Lu Weiguo; Olivera, Gustavo H; Chen, Quan; Ruchala, Kenneth J; Haimerl, Jason; Meeks, Sanford L; Langen, Katja M; Kupelian, Patrick A

2006-01-01

The incorporation of daily images into the radiotherapy process leads to adaptive radiation therapy (ART), in which the treatment is evaluated periodically and the plan is adaptively modified for the remaining course of radiotherapy. Deformable registration between the planning image and the daily images is a key component of ART. In this paper, we report our researches on deformable registration between the planning kVCT and the daily MVCT image sets. The method is based on a fast intensity-based free-form deformable registration technique. Considering the noise and contrast resolution differences between the kVCT and the MVCT, an 'edge-preserving smoothing' is applied to the MVCT image prior to the deformable registration process. We retrospectively studied daily MVCT images from commercial TomoTherapy machines from different clinical centers. The data set includes five head-neck cases, one pelvis case, two lung cases and one prostate case. Each case has one kVCT image and 20-40 MVCT images. We registered the MVCT images with their corresponding kVCT image. The similarity measures and visual inspections of contour matches by physicians validated this technique. The applications of deformable registration in ART, including 'deformable dose accumulation', 'automatic re-contouring' and 'tumour growth/regression evaluation' throughout the course of radiotherapy are also studied

Automatic analysis of image quality control for Image Guided Radiation Therapy (IGRT) devices in external radiotherapy

International Nuclear Information System (INIS)

Torfeh, Tarraf

2009-01-01

On-board imagers mounted on a radiotherapy treatment machine are very effective devices that improve the geometric accuracy of radiation delivery. However, a precise and regular quality control program is required in order to achieve this objective. Our purpose consisted of developing software tools dedicated to an automatic image quality control of IGRT devices used in external radiotherapy: 2D-MV mode for measuring patient position during the treatment using high energy images, 2D-kV mode (low energy images) and 3D Cone Beam Computed Tomography (CBCT) MV or kV mode, used for patient positioning before treatment. Automated analysis of the Winston and Lutz test was also proposed. This test is used for the evaluation of the mechanical aspects of treatment machines on which additional constraints are carried out due to the on-board imagers additional weights. Finally, a technique of generating digital phantoms in order to assess the performance of the proposed software tools is described. Software tools dedicated to an automatic quality control of IGRT devices allow reducing by a factor of 100 the time spent by the medical physics team to analyze the results of controls while improving their accuracy by using objective and reproducible analysis and offering traceability through generating automatic monitoring reports and statistical studies. (author) [fr

A practical implementation of physics quality assurance for photon adaptive radiotherapy.

Science.gov (United States)

Cai, Bin; Green, Olga L; Kashani, Rojano; Rodriguez, Vivian L; Mutic, Sasa; Yang, Deshan

2018-03-14

The fast evolution of technology in radiotherapy (RT) enabled the realization of adaptive radiotherapy (ART). However, the new characteristics of ART pose unique challenges for efficiencies and effectiveness of quality assurance (QA) strategies. In this paper, we discuss the necessary QAs for ART and introduce a practical implementation. A previously published work on failure modes and effects analysis (FMEA) of ART is introduced first to explain the risks associated with ART sub-processes. After a brief discussion of QA challenges, we review the existing QA strategies and tools that might be suitable for each ART step. By introducing the MR-guided online ART QA processes developed at our institute, we demonstrate a practical implementation. The limitations and future works to develop more robust and efficient QA strategies are discussed at the end. Copyright © 2018. Published by Elsevier GmbH.

The outcome of a multi-centre feasibility study of online adaptive radiotherapy for muscle-invasive bladder cancer TROG 10.01 BOLART

International Nuclear Information System (INIS)

Foroudi, Farshad; Pham, Daniel; Rolfo, Aldo; Bressel, Mathias; Tang, Colin I.; Tan, Alex; Turner, Sandra; Hruby, George; Williams, Stephen; Hayne, Dickon; Lehman, Margot; Skala, Marketa; Jose, Chakiath C.; Gogna, Kumar; Kron, Tomas

2014-01-01

Purpose: To assess whether online adaptive radiotherapy for bladder cancer is feasible across multiple Radiation Oncology departments using different imaging, delivery and recording technology. Materials and methods: A multi-centre feasibility study of online adaptive radiotherapy, using a choice of three “plan of the day”, was conducted at 12 departments. Patients with muscle-invasive bladder cancer were included. Departments were activated if part of the pilot study or after a site-credentialing visit. There was real time review of the first two cases from each department. Results: 54 patients were recruited, with 50 proceeding to radiotherapy. There were 43 males and 7 females with a mean age of 78 years. The tumour stages treated included T1 (1 patient), T2 (35), T3 (10) and T4 (4). One patient died of an unrelated cause during radiotherapy. The three adaptive plans were created before the 10th fraction in all cases. In 8 (16%) of the patients, a conventional plan using a ‘standard’ CTV to PTV margin of 1.5 cm was used for one or more fractions where the pre-treatment bladder CTV was larger than any of the three adaptive plans. The bladder CTV extended beyond the PTV on post treatment imaging in 9 (18%) of the 49 patients. Conclusions: From a technical perspective an online adaptive radiotherapy technique can be instituted in a multi-centre setting. However, without further bladder filling control or imaging, a CTV to PTV margin of 7 mm is insufficient

Image denoising via adaptive eigenvectors of graph Laplacian

Science.gov (United States)

Chen, Ying; Tang, Yibin; Xu, Ning; Zhou, Lin; Zhao, Li

2016-07-01

An image denoising method via adaptive eigenvectors of graph Laplacian (EGL) is proposed. Unlike the trivial parameter setting of the used eigenvectors in the traditional EGL method, in our method, the eigenvectors are adaptively selected in the whole denoising procedure. In detail, a rough image is first built with the eigenvectors from the noisy image, where the eigenvectors are selected by using the deviation estimation of the clean image. Subsequently, a guided image is effectively restored with a weighted average of the noisy and rough images. In this operation, the average coefficient is adaptively obtained to set the deviation of the guided image to approximately that of the clean image. Finally, the denoised image is achieved by a group-sparse model with the pattern from the guided image, where the eigenvectors are chosen in the error control of the noise deviation. Moreover, a modified group orthogonal matching pursuit algorithm is developed to efficiently solve the above group sparse model. The experiments show that our method not only improves the practicality of the EGL methods with the dependence reduction of the parameter setting, but also can outperform some well-developed denoising methods, especially for noise with large deviations.

Fiducial registration error as a statistical process control metric in image-guided radiotherapy with prostatic markers

International Nuclear Information System (INIS)

Ung, M.N.; Wee, Leonard

2010-01-01

Full text: Portal imaging of implanted fiducial markers has been in use for image-guided radiotherapy (TORT) of prostate cancer, with ample attention to localization accuracy and organ motion. The geometric uncertainties in point-based rigid-body (PBRB) image registration during localization of prostate fiducial markers can be quantified in terms of a fiducial registration error (FRE). Statistical process control charts for individual patients can be designed to identify potentially significant deviation of FRE from expected behaviour. In this study, the aim was to retrospectively apply statistical process control methods to FREs in 34 individuals to identify parameters that may impact on the process stability in image-based localization. A robust procedure for estimating control parameters, control lim its and fixed tolerance levels from a small number of initial observations has been proposed and discussed. Four distinct types of qualitative control chart behavior have been observed. Probable clinical factors leading to IORT process instability are discussed in light of the control chart behaviour. Control charts have been shown to be a useful decision-making tool for detecting potentially out-of control processes on an individual basis. It can sensitively identify potential problems that warrant more detailed investigation in the 10RT of prostate cancer.

Adaptive treatment-length optimization in spatiobiologically integrated radiotherapy

Science.gov (United States)

Ajdari, Ali; Ghate, Archis; Kim, Minsun

2018-04-01

Recent theoretical research on spatiobiologically integrated radiotherapy has focused on optimization models that adapt fluence-maps to the evolution of tumor state, for example, cell densities, as observed in quantitative functional images acquired over the treatment course. We propose an optimization model that adapts the length of the treatment course as well as the fluence-maps to such imaged tumor state. Specifically, after observing the tumor cell densities at the beginning of a session, the treatment planner solves a group of convex optimization problems to determine an optimal number of remaining treatment sessions, and a corresponding optimal fluence-map for each of these sessions. The objective is to minimize the total number of tumor cells remaining (TNTCR) at the end of this proposed treatment course, subject to upper limits on the biologically effective dose delivered to the organs-at-risk. This fluence-map is administered in future sessions until the next image is available, and then the number of sessions and the fluence-map are re-optimized based on the latest cell density information. We demonstrate via computer simulations on five head-and-neck test cases that such adaptive treatment-length and fluence-map planning reduces the TNTCR and increases the biological effect on the tumor while employing shorter treatment courses, as compared to only adapting fluence-maps and using a pre-determined treatment course length based on one-size-fits-all guidelines.

SU-E-J-159: Analysis of Total Imaging Uncertainty in Respiratory-Gated Radiotherapy

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Suzuki, J; Okuda, T [Toyota memorial hospital, Toyota, Aichi (Japan); Sakaino, S; Yokota, N [Suzukake central hospital, Hamamatsu, Shizuoka (Japan)

2015-06-15

Purpose: In respiratory-gated radiotherapy, the gating phase during treatment delivery needs to coincide with the corresponding phase determined during the treatment plan. However, because radiotherapy is performed based on the image obtained for the treatment plan, the time delay, motion artifact, volume effect, and resolution in the images are uncertain. Thus, imaging uncertainty is the most basic factor that affects the localization accuracy. Therefore, these uncertainties should be analyzed. This study aims to analyze the total imaging uncertainty in respiratory-gated radiotherapy. Methods: Two factors of imaging uncertainties related to respiratory-gated radiotherapy were analyzed. First, CT image was used to determine the target volume and 4D treatment planning for the Varian Realtime Position Management (RPM) system. Second, an X-ray image was acquired for image-guided radiotherapy (IGRT) for the BrainLAB ExacTrac system. These factors were measured using a respiratory gating phantom. The conditions applied during phantom operation were as follows: respiratory wave form, sine curve; respiratory cycle, 4 s; phantom target motion amplitude, 10, 20, and 29 mm (which is maximum phantom longitudinal motion). The target and cylindrical marker implanted in the phantom coverage of the CT images was measured and compared with the theoretically calculated coverage from the phantom motion. The theoretical position of the cylindrical marker implanted in the phantom was compared with that acquired from the X-ray image. The total imaging uncertainty was analyzed from these two factors. Results: In the CT image, the uncertainty between the target and cylindrical marker’s actual coverage and the coverage of CT images was 1.19 mm and 2.50mm, respectively. In the Xray image, the uncertainty was 0.39 mm. The total imaging uncertainty from the two factors was 1.62mm. Conclusion: The total imaging uncertainty in respiratory-gated radiotherapy was clinically acceptable. However

SU-E-J-159: Analysis of Total Imaging Uncertainty in Respiratory-Gated Radiotherapy

International Nuclear Information System (INIS)

Suzuki, J; Okuda, T; Sakaino, S; Yokota, N

2015-01-01

Purpose: In respiratory-gated radiotherapy, the gating phase during treatment delivery needs to coincide with the corresponding phase determined during the treatment plan. However, because radiotherapy is performed based on the image obtained for the treatment plan, the time delay, motion artifact, volume effect, and resolution in the images are uncertain. Thus, imaging uncertainty is the most basic factor that affects the localization accuracy. Therefore, these uncertainties should be analyzed. This study aims to analyze the total imaging uncertainty in respiratory-gated radiotherapy. Methods: Two factors of imaging uncertainties related to respiratory-gated radiotherapy were analyzed. First, CT image was used to determine the target volume and 4D treatment planning for the Varian Realtime Position Management (RPM) system. Second, an X-ray image was acquired for image-guided radiotherapy (IGRT) for the BrainLAB ExacTrac system. These factors were measured using a respiratory gating phantom. The conditions applied during phantom operation were as follows: respiratory wave form, sine curve; respiratory cycle, 4 s; phantom target motion amplitude, 10, 20, and 29 mm (which is maximum phantom longitudinal motion). The target and cylindrical marker implanted in the phantom coverage of the CT images was measured and compared with the theoretically calculated coverage from the phantom motion. The theoretical position of the cylindrical marker implanted in the phantom was compared with that acquired from the X-ray image. The total imaging uncertainty was analyzed from these two factors. Results: In the CT image, the uncertainty between the target and cylindrical marker’s actual coverage and the coverage of CT images was 1.19 mm and 2.50mm, respectively. In the Xray image, the uncertainty was 0.39 mm. The total imaging uncertainty from the two factors was 1.62mm. Conclusion: The total imaging uncertainty in respiratory-gated radiotherapy was clinically acceptable. However

Anatomical imaging for radiotherapy

International Nuclear Information System (INIS)

Evans, Philip M

2008-01-01

The goal of radiation therapy is to achieve maximal therapeutic benefit expressed in terms of a high probability of local control of disease with minimal side effects. Physically this often equates to the delivery of a high dose of radiation to the tumour or target region whilst maintaining an acceptably low dose to other tissues, particularly those adjacent to the target. Techniques such as intensity modulated radiotherapy (IMRT), stereotactic radiosurgery and computer planned brachytherapy provide the means to calculate the radiation dose delivery to achieve the desired dose distribution. Imaging is an essential tool in all state of the art planning and delivery techniques: (i) to enable planning of the desired treatment, (ii) to verify the treatment is delivered as planned and (iii) to follow-up treatment outcome to monitor that the treatment has had the desired effect. Clinical imaging techniques can be loosely classified into anatomic methods which measure the basic physical characteristics of tissue such as their density and biological imaging techniques which measure functional characteristics such as metabolism. In this review we consider anatomical imaging techniques. Biological imaging is considered in another article. Anatomical imaging is generally used for goals (i) and (ii) above. Computed tomography (CT) has been the mainstay of anatomical treatment planning for many years, enabling some delineation of soft tissue as well as radiation attenuation estimation for dose prediction. Magnetic resonance imaging is fast becoming widespread alongside CT, enabling superior soft-tissue visualization. Traditionally scanning for treatment planning has relied on the use of a single snapshot scan. Recent years have seen the development of techniques such as 4D CT and adaptive radiotherapy (ART). In 4D CT raw data are encoded with phase information and reconstructed to yield a set of scans detailing motion through the breathing, or cardiac, cycle. In ART a set of

Design of planning target volume margin using an active breathing control and Varian image-guided radiotherapy (IGRT) system in unresectable liver tumor

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Yue Jinbo; Yu Jinming; Liu Jing; Liu Tonghai; Yin Yong; Shi Xuetao; Song Jinlong

2007-01-01

Objective: To define the planning target volume(PTV) margin with an active breathing control (ABC) and the Varian image-guided radiotherapy (IGRT) system. Methods: Thirteen patients with liver cancer were treated with radiotherapy from May 2006 to September 2006. Prior to radiotherapy, all patients had undergone transarterial chemoembolization (TACE) by infusing a mixture of iodized oil contrast medium and chemotherapeutic agents, kV fluoroscopy was used to measure the potential motion of lipiodol spot positions during ABC breath-holds. ABC was used for planning CT scan and radiation delivery, with the breath held at the same phase of the respiratory cycle (near end-exhalation). Cone beam CT (CBCT) was taken using Varian IGRT system, which was then compared online with planning CT using a 3 D-3 D matching tool. Analysis relied on lipiodol spots on planning CT and CBCT manually. The treatment table was moved to produce acceptable setup before treatment delivery. Repeated CBCT image and another analysis were obtained after irradiation. Results: No motion of the intrahepatic tumor was observed on fluoroscopy during ABC breath-holds. The estimated required PTV margins, calculated according to the Stroom formula, were 4.4 mm, 5.3 mm and 7.8 mm in the x, y and z axis directions before radiotherapy. The corresponding parameters were 2.5m, 2.6 mm and 3.9 mm after radiotherapy. Conclusions: We have adopted a PTV margin of 5 mm, 6 mm and 8 mm in the x, y and z axis directions with ABC, and 3,3 and 4 mm with ABC and on-line kilovoltage CBCT. (authors)

Clinical Outcome of Dose-Escalated Image-Guided Radiotherapy for Spinal Metastases

International Nuclear Information System (INIS)

Guckenberger, Matthias; Goebel, Joachim; Wilbert, Juergen; Baier, Kurt; Richter, Anne; Sweeney, Reinhart A.; Bratengeier, Klaus; Flentje, Michael

2009-01-01

Purpose: To evaluate the outcomes after dose-escalated radiotherapy (RT) for spinal metastases and paraspinal tumors. Methods and Materials: A total of 14 patients, 12 with spinal metastases and a long life expectancy and 2 with paraspinal tumors, were treated for 16 lesions with intensity-modulated, image-guided RT. A median biologic effective dose of 74 Gy 10 (range, 55-86) in a median of 20 fractions (range, 3-34) was prescribed to the target volume. The spinal canal was treated to 40 Gy in 20 fractions using a second intensity-modulated RT dose level in the case of epidural involvement. Results: After median follow-up of 17 months, one local recurrence was observed, for an actuarial local control rate of 88% after 2 years. Local control was associated with rapid and long-term pain relief. Of 11 patients treated for a solitary spinal metastasis, 6 developed systemic disease progression. The actuarial overall survival rate for metastatic patients was 85% and 63% after 1 and 2 years, respectively. Acute Grade 2-3 skin toxicity was seen in 2 patients with no late toxicity greater than Grade 2. No radiation-induced myelopathy was observed. Conclusion: Dose-escalated irradiation of spinal metastases was safe and resulted in excellent local control. Oligometastatic patients with a long life expectancy and epidural involvement are considered to benefit the most from fractionated RT.

Image guided radiotherapy: equipment specifications and performance - an analysis of the dosimetric consequences of anatomic variations during head-and-neck radiotherapy treatment

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Marguet, Maud

2009-01-01

Anatomic variations during head-and-neck radiotherapy treatment may compromise the delivery of the planned dose distribution, particularly in the case of IMRT treatments. The aim of this thesis was to establish 'dosimetric indicators' to identify patients who delivered dose deviates from the planned dose, to allow an eventual re-optimisation of the patient's dosimetry, if necessary, during the course of their radiotherapy treatment. These anatomic variations were monitored by regular acquisition of 3D patient images using an onboard imaging system, for which a rigorous quality control program was implemented. The patient dose distribution analysis and comparison was performed using a modified gamma index technique which was named gammaLSC3D. This improved gamma index technique quantified and identified the location of changes in the dose distribution in a stack of 2D images, with particular reference to the target volume (PTV) or organs at risk (parotids). The changes observed in the dose distribution for the PTV or parotids were then analysed and presented in the form of gamma-volume histograms in order to facilitate the follow up of dosimetric changes during the radiotherapy treatment. This analysis method has been automated, and is applicable in clinical routine to follow dose variations during head and neck radiotherapy treatment. (author) [fr

Introducing an on-line adaptive procedure for prostate image guided intensity modulate proton therapy.

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Zhang, M; Westerly, D C; Mackie, T R

2011-08-07

With on-line image guidance (IG), prostate shifts relative to the bony anatomy can be corrected by realigning the patient with respect to the treatment fields. In image guided intensity modulated proton therapy (IG-IMPT), because the proton range is more sensitive to the material it travels through, the realignment may introduce large dose variations. This effect is studied in this work and an on-line adaptive procedure is proposed to restore the planned dose to the target. A 2D anthropomorphic phantom was constructed from a real prostate patient's CT image. Two-field laterally opposing spot 3D-modulation and 24-field full arc distal edge tracking (DET) plans were generated with a prescription of 70 Gy to the planning target volume. For the simulated delivery, we considered two types of procedures: the non-adaptive procedure and the on-line adaptive procedure. In the non-adaptive procedure, only patient realignment to match the prostate location in the planning CT was performed. In the on-line adaptive procedure, on top of the patient realignment, the kinetic energy for each individual proton pencil beam was re-determined from the on-line CT image acquired after the realignment and subsequently used for delivery. Dose distributions were re-calculated for individual fractions for different plans and different delivery procedures. The results show, without adaptive, that both the 3D-modulation and the DET plans experienced delivered dose degradation by having large cold or hot spots in the prostate. The DET plan had worse dose degradation than the 3D-modulation plan. The adaptive procedure effectively restored the planned dose distribution in the DET plan, with delivered prostate D(98%), D(50%) and D(2%) values less than 1% from the prescription. In the 3D-modulation plan, in certain cases the adaptive procedure was not effective to reduce the delivered dose degradation and yield similar results as the non-adaptive procedure. In conclusion, based on this 2D phantom

Image-Guided Radiotherapy via Daily Online Cone-Beam CT Substantially Reduces Margin Requirements for Stereotactic Lung Radiotherapy

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Grills, Inga S.; Hugo, Geoffrey; Kestin, Larry L.; Galerani, Ana Paula; Chao, K. Kenneth; Wloch, Jennifer; Yan Di

2008-01-01

Purpose: To determine treatment accuracy and margins for stereotactic lung radiotherapy with and without cone-beam CT (CBCT) image guidance. Methods and Materials: Acquired for the study were 308 CBCT of 24 patients with solitary peripheral lung tumors treated with stereotactic radiotherapy. Patients were immobilized in a stereotactic body frame (SBF) or alpha-cradle and treated with image guidance using daily CBCT. Four (T1) or five (T2/metastatic) 12-Gy fractions were prescribed to the planning target volume (PTV) edge. The PTV margin was ≥5 mm depending on a pretreatment estimate of tumor excursion. Initial daily setup was according to SBF coordinates or tattoos for alpha-cradle cases. A CBCT was performed and registered to the planning CT using soft tissue registration of the target. The initial setup error/precorrection position, was recorded for the superior-inferior, anterior-posterior, and medial-lateral directions. The couch was adjusted to correct the tumor positional error. A second CBCT verified tumor position after correction. Patients were treated in the corrected position after the residual errors were ≤2 mm. A final CBCT after treatment assessed intrafraction tumor displacement. Results: The precorrection systematic (Σ) and random errors (σ) for the population ranged from 2-3 mm for SBF and 2-6 mm for alpha-cradle patients; postcorrection errors ranged from 0.4-1.0 mm. Calculated population margins were 9 to 13 mm (SBF) and 10-14 mm (cradle) precorrection, 1-2 mm (SBF), and 2-3 mm (cradle) postcorrection, and 2-4 mm (SBF) and 2-5 mm (cradle) posttreatment. Conclusions: Setup for stereotactic lung radiotherapy using a SBF or alpha-cradle alone is suboptimal. CBCT image guidance significantly improves target positioning and substantially reduces required target margins and normal tissue irradiation

Image-guided positioning and tracking.

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Ruan, Dan; Kupelian, Patrick; Low, Daniel A

2011-01-01

Radiation therapy aims at maximizing tumor control while minimizing normal tissue complication. The introduction of stereotactic treatment explores the volume effect and achieves dose escalation to tumor target with small margins. The use of ablative irradiation dose and sharp dose gradients requires accurate tumor definition and alignment between patient and treatment geometry. Patient geometry variation during treatment may significantly compromise the conformality of delivered dose and must be managed properly. Setup error and interfraction/intrafraction motion are incorporated in the target definition process by expanding the clinical target volume to planning target volume, whereas the alignment between patient and treatment geometry is obtained with an adaptive control process, by taking immediate actions in response to closely monitored patient geometry. This article focuses on the monitoring and adaptive response aspect of the problem. The term "image" in "image guidance" will be used in a most general sense, to be inclusive of some important point-based monitoring systems that can be considered as degenerate cases of imaging. Image-guided motion adaptive control, as a comprehensive system, involves a hierarchy of decisions, each of which balances simplicity versus flexibility and accuracy versus robustness. Patient specifics and machine specifics at the treatment facility also need to be incorporated into the decision-making process. Identifying operation bottlenecks from a system perspective and making informed compromises are crucial in the proper selection of image-guidance modality, the motion management mechanism, and the respective operation modes. Not intended as an exhaustive exposition, this article focuses on discussing the major issues and development principles for image-guided motion management systems. We hope these information and methodologies will facilitate conscientious practitioners to adopt image-guided motion management systems

Usefulness of a guide book for patients to self-help during radiotherapy for anxiety before radiotherapy

International Nuclear Information System (INIS)

Hoshino, Naoko; Yamada, Nami; Morita, Kozo.

1995-01-01

From May through August 1993, 'a guide book for patients to self-help during radiotherapy' prepared at our department was given 80 patients before radiotherapy and the usefulness of this book for understanding of radiotherapy and reduction of anxiety for radiotherapy was investigated. In 83% of patients could read it through, and in 67% of these patients anxiety for treatment reduced. It is necessary that medical staffs make it clear more often, to let them understand this book more correctly. (author)

Performance of a Novel Repositioning Head Frame for Gamma Knife Perfexion and Image-Guided Linac-Based Intracranial Stereotactic Radiotherapy

International Nuclear Information System (INIS)

Ruschin, Mark; Nayebi, Nazanin; Carlsson, Per; Brown, Kevin

2010-01-01

Purpose: To evaluate the geometric positioning and immobilization performance of a vacuum bite-block repositioning head frame (RHF) system for Perfexion (PFX-SRT) and linac-based intracranial image-guided stereotactic radiotherapy (SRT). Methods and Materials: Patients with intracranial tumors received linac-based image-guided SRT using the RHF for setup and immobilization. Three hundred thirty-three fractions of radiation were delivered in 12 patients. The accuracy of the RHF was estimated for linac-based SRT with online cone-beam CT (CBCT) and for PFX-SRT with a repositioning check tool (RCT) and offline CBCT. The RCT's ability to act as a surrogate for anatomic position was estimated through comparison to CBCT image matching. Immobilization performance was evaluated daily with pre- and postdose delivery CBCT scans and RCT measurements. Results: The correlation coefficient between RCT- and CBCT-reported displacements was 0.59, 0.75, 0.79 (Right, Superior, and Anterior, respectively). For image-guided linac-based SRT, the mean three-dimensional (3D) setup error was 0.8 mm with interpatient (Σ) and interfraction (σ) variations of 0.1 and 0.4 mm, respectively. For PFX-SRT, the initial, uncorrected mean 3D positioning displacement in stereotactic coordinates was 2.0 mm, with Σ = 1.1 mm and σ = 0.8 mm. Considering only RCT setups o in pitch. The mean 3D intrafraction motion was 0.4 ± 0.3 mm. Conclusion: The RHF provides excellent immobilization for intracranial SRT and PFX-SRT. Some small systematic uncertainties in stereotactic positioning exist and must be considered when generating PFX-SRT treatment plans. The RCT provides reasonable surrogacy for internal anatomic displacement.

Reduced rectal toxicity with ultrasound-based image guided radiotherapy using BAT trademark (B-mode acquisition and targeting system) for prostate cancer

International Nuclear Information System (INIS)

Bohrer, Markus; Schroeder, Peter; Welzel, Grit; Wertz, Hansjoerg; Lohr, Frank; Wenz, Frederik; Mai, Sabine Kathrin

2008-01-01

To evaluate the effect of image guided radiotherapy with stereotactic ultrasound BAT (B-mode acquisition and targeting system) on rectal toxicity in conformal radiotherapy of prostate cancer. Patients and Methods 42 sequential patients with prostate cancer undergoing radiotherapy before and after the introduction of BAT were included. Planning computed tomography (CT) was performed with empty rectum and moderately filled bladder. The planning target volume (PTV) included the prostate and seminal vesicles with a safety margin of 1.5 cm in anterior and lateral direction. In posterior direction the anterior 1/3 of the rectum circumference were included. Total dose was 66 Gy and a boost of 4 Gy excluding the seminal vesicles. 22 patients (BAT group) were treated with daily stereotactic ultrasound positioning, for the other 20 patients (NoBAT group) an EPID (electronic portal imaging device) was performed once a week. Acute and late genito-urinary (GU) and rectal toxicity and PSA values were evaluated after 1.5, 3, 6, 9 and 12 months. The total median follow up of toxicity was 3 years in the BAT group and 4 years in the NoBAT group. Results In the NoBAT group significant more rectal toxicity occurred, while in GU toxicity no difference was seen. Two patients in the NoBAT group showed late rectal toxicity grade 3, no toxicity > grade 2 occurred in the BAT group. There was no significant difference in PSA reduction between the groups. Conclusion Without BAT significant more acute and a trend to more late rectal toxicity was found. With regard to dose escalation this aspect is currently evaluated with a larger number of patients using intensity-modulated radiotherapy (IMRT). (orig.)

Implementation of an image guided intensity-modulated protocol for post-prostatectomy radiotherapy: planning data and acute toxicity outcomes

International Nuclear Information System (INIS)

Chua, Benjamin; Min, Myo; Wood, Maree; Edwards, Sarah; Hoffmann, Matthew; Greenham, Stuart; Kovendy, Andrew; McKay, Michael J.; Shakespeare, Thomas P.

2013-01-01

There is substantial interest in implementation of image-guided intensity-modulated radiotherapy (IG-IMRT) in the post-prostatectomy setting. We describe our implementation of IG-IMRT, and examine how often published organ-at-risk (OAR) constraints were met. Furthermore, we evaluate the incidence of acute genitourinary and gastrointestinal toxicities when patients were treated according to our protocol. Patients were eligible if they received post-prostatectomy radiotherapy (PPRT). Planning data were collected prospectively, and toxicity assessments were collected before, during and after treatment. Seventy-five eligible patients received either 64Gy (19%) or 66Gy (81%) in a single phase to the prostate bed. Suggested rectal dose-constraints of V40Gy<60% and V60Gy<40% were met in 64 (85%) and 75 (100%) patients, respectively. IMRT-specific rectal dose-constraints of V40Gy<35% and V65Gy<17% were achieved in 5 (7%) and 57 (76%) of patients. Bladder dose-constraint (V50Gy<50%) was met in 58 (77%) patients. Two patients (3%) experienced new grade 3 genitourinary toxicity and one patient (1%) experienced new grade 3 gastrointestinal toxicity. All grade 3 toxicities had improved by 3-month review. Overall deterioration in urinary and gastrointestinal symptoms occurred in 33 (44%) and 35 (47%) of patients respectively. We report on our implementation of PPRT which takes into account nationally adopted guidelines, with a margin reduction supported by use of daily image guidance. Non-IMRT OAR constraints were met in most cases. IMRT-specific constraints were less often achieved despite margin reductions, suggesting the need for review of guidelines. Severe toxicity was rare, and most patients did not experience deterioration in urinary or bowel function attributable to radiotherapy.

Initial application of a geometric QA tool for integrated MV and kV imaging systems on three image guided radiotherapy systems.

Science.gov (United States)

Mao, Weihua; Speiser, Michael; Medin, Paul; Papiez, Lech; Solberg, Timothy; Xing, Lei

2011-05-01

Several linacs with integrated kilovoltage (kV) imaging have been developed for delivery of image guided radiation therapy (IGRT). High geometric accuracy and coincidence of kV imaging systems and megavoltage (MV) beam delivery are essential for successful image guidance. A geometric QA tool has been adapted for routine QA for evaluating and characterizing the geometric accuracy of kV and MV cone-beam imaging systems. The purpose of this work is to demonstrate the application of methodology to routine QA across three IGRT-dedicated linac platforms. It has been applied to a Varian Trilogy (Varian Medical Systems, Palo Alto, CA), an Elekta SynergyS (Elekta, Stockholm, Sweden), and a Brainlab Vero (Brainlab AG, Feldkirchen, Germany). Both the Trilogy and SynergyS linacs are equipped with a retractable kV x-ray tube and a flat panel detector. The Vero utilizes a rotating, rigid ring structure integrating a MV x-ray head mounted on orthogonal gimbals, an electronic portal imaging device (EPID), two kV x-ray tubes, and two fixed flat panel detectors. This dual kV imaging system provides orthogonal radiographs, CBCT images, and real-time fluoroscopic monitoring. Two QA phantoms were built to suit different field sizes. Projection images of a QA phantom were acquired using MV and kV imaging systems at a series of gantry angles. Software developed for this study was used to analyze the projection images and calculate nine geometric parameters for each projection. The Trilogy was characterized five times over one year, while the SynergyS was characterized four times and the Vero once. Over 6500 individual projections were acquired and analyzed. Quantitative geometric parameters of both MV and kV imaging systems, as well as the isocenter consistency of the imaging systems, were successfully evaluated. A geometric tool has been successfully implemented for calibration and QA of integrated kV and MV across a variety of radiotherapy platforms. X-ray source angle deviations up to

An image-guided radiotherapy decision support framework incorporating a Bayesian network and visualization tool.

Science.gov (United States)

Hargrave, Catriona; Deegan, Timothy; Bednarz, Tomasz; Poulsen, Michael; Harden, Fiona; Mengersen, Kerrie

2018-05-17

To describe a Bayesian network (BN) and complementary visualization tool that aim to support decision-making during online cone-beam computed tomography (CBCT)-based image-guided radiotherapy (IGRT) for prostate cancer patients. The BN was created to represent relationships between observed prostate, proximal seminal vesicle (PSV), bladder and rectum volume variations, an image feature alignment score (FAS TV _ OAR ), delivered dose, and treatment plan compliance (TPC). Variables influencing tumor volume (TV) targeting accuracy such as intrafraction motion, and contouring and couch shift errors were also represented. A score of overall TPC (FAS global ) and factors such as image quality were used to inform the BN output node providing advice about proceeding with treatment. The BN was quantified using conditional probabilities generated from published studies, FAS TV _ OAR /global modeling, and a survey of IGRT decision-making practices. A new IGRT visualization tool (IGRT REV ), in the form of Mollweide projection plots, was developed to provide a global summary of residual errors after online CBCT-planning CT registration. Sensitivity and scenario analyses were undertaken to evaluate the performance of the BN and the relative influence of the network variables on TPC and the decision to proceed with treatment. The IGRT REV plots were evaluated in conjunction with the BN scenario testing, using additional test data generated from retrospective CBCT-planning CT soft-tissue registrations for 13/36 patients whose data were used in the FAS TV _ OAR /global modeling. Modeling of the TV targeting errors resulted in a very low probability of corrected distances between the CBCT and planning CT prostate or PSV volumes being within their thresholds. Strength of influence evaluation with and without the BN TV targeting error nodes indicated that rectum- and bladder-related network variables had the highest relative importance. When the TV targeting error nodes were excluded

Promising results with image guided intensity modulated radiotherapy for muscle invasive bladder cancer

International Nuclear Information System (INIS)

Whalley, D.; Caine, H.; McCloud, P.; Guo, L.; Kneebone, A.; Eade, T.

2015-01-01

To describe the feasibility of image guided intensity modulated radiotherapy (IG-IMRT) using daily soft tissue matching in the treatment of bladder cancer. Twenty-eight patients with muscle-invasive carcinoma of the bladder were recruited to a protocol of definitive radiation using IMRT with accelerated hypofractionation with simultaneous integrated boost (SIB). Isotropic margins of .5 and 1 cm were used to generate the high risk and intermediate risk planning target volumes respectively. Cone beam CT (CBCT) was acquired daily and a soft tissue match was performed. Cystoscopy was scheduled 6 weeks post treatment. The median age was 83 years (range 58-92). Twenty patients had stage II or III disease, and eight were stage IV. Gross disease received 66 Gy in 30 fractions in 11 patients (ten with concurrent chemotherapy) or 55 Gy in 20 fractions for those of poorer performance status or with palliative intent. All patients completed radiation treatment as planned. Three patients ceased chemotherapy early due to toxicity. Six patients (21 %) had acute Grade ≥ 2 genitourinary (GU) toxicity and six (21 %) had acute Grade ≥ 2 gastrointestinal (GI) toxicity. Five patients (18 %) developed Grade ≥2 late GU toxicity and no ≥2 late GI toxicity was observed. Nineteen patients underwent cystoscopy following radiation, with complete response (CR) in 16 cases (86 %), including all patients treated with chemoradiotherapy. Eight patients relapsed, four of which were local relapses. Of the patients with local recurrence, one underwent salvage cystectomy. For patients treated with definitive intent, freedom from locoregional recurrence (FFLR) and overall survival (OS) was 90 %/100 % for chemoradiotherapy versus 86 %/69 % for radiotherapy alone. IG- IMRT using daily soft tissue matching is a feasible in the treatment of bladder cancer, enabling the delivery of accelerated synchronous integrated boost with good early local control outcomes and low toxicity

MO-E-BRD-01: Adapt-A-Thon - Texas Hold’em Invitational

International Nuclear Information System (INIS)

Kessler, M; Brock, K; Pouliot, J; Dong, L

2014-01-01

Software tools for image-based adaptive radiotherapy such as deformable image registration, contour propagation and dose mapping have progressed beyond the research setting and are now commercial products available as part of both treatment planning systems and stand-alone applications. These software tools are used together to create clinical workflows to detect, track and evaluate changes in the patient and to accumulate dose. Deviations uncovered in this process are used to guide decisions about replanning/adaptation with the goal of keeping the delivery of prescribed dose “on target” throughout the entire course of radiotherapy. Since the output from one step of the adaptive process is used as an input for another, it is essential to understand and document the uncertainty associated with each of the step and how these uncertainties are propagated. This in turn requires an understanding how the underlying tools work. Unfortunately, important details about the algorithms used to implement these tools are scarce or incomplete, too often for competitive reasons. This is in contrast to the situation involving other basic treatment planning algorithms such as dose calculations, where the medical physics community essentially requires vendors to provide physically important details about their underlying theory and clinical implementation. Vendors should adopt this same level of information sharing when it comes to the tools and techniques for image guided adaptive radiotherapy. The goal of this session is to start this process by inviting vendors and medical physicists to discuss and demonstrate the available tools and describe how they are intended to be used in clinical practice. The format of the session will involve a combination of formal presentations, interactive demonstrations, audience participation and some friendly “Texas style” competition. Learning Objectives: Understand the components of the image-based adaptive radiotherapy process. Understand

MO-E-BRD-01: Adapt-A-Thon - Texas Hold’em Invitational

Energy Technology Data Exchange (ETDEWEB)

Kessler, M; Brock, K; Pouliot, J; Dong, L [The University of Michigan, Ann Arbor, MI (United States)

2014-06-15

Software tools for image-based adaptive radiotherapy such as deformable image registration, contour propagation and dose mapping have progressed beyond the research setting and are now commercial products available as part of both treatment planning systems and stand-alone applications. These software tools are used together to create clinical workflows to detect, track and evaluate changes in the patient and to accumulate dose. Deviations uncovered in this process are used to guide decisions about replanning/adaptation with the goal of keeping the delivery of prescribed dose “on target” throughout the entire course of radiotherapy. Since the output from one step of the adaptive process is used as an input for another, it is essential to understand and document the uncertainty associated with each of the step and how these uncertainties are propagated. This in turn requires an understanding how the underlying tools work. Unfortunately, important details about the algorithms used to implement these tools are scarce or incomplete, too often for competitive reasons. This is in contrast to the situation involving other basic treatment planning algorithms such as dose calculations, where the medical physics community essentially requires vendors to provide physically important details about their underlying theory and clinical implementation. Vendors should adopt this same level of information sharing when it comes to the tools and techniques for image guided adaptive radiotherapy. The goal of this session is to start this process by inviting vendors and medical physicists to discuss and demonstrate the available tools and describe how they are intended to be used in clinical practice. The format of the session will involve a combination of formal presentations, interactive demonstrations, audience participation and some friendly “Texas style” competition. Learning Objectives: Understand the components of the image-based adaptive radiotherapy process. Understand

Temporary organ displacement coupled with image-guided, intensity-modulated radiotherapy for paraspinal tumors

International Nuclear Information System (INIS)

Katsoulakis, Evangelia; Thornton, Raymond H; Yamada, Yoshiya; Solomon, Stephen B; Maybody, Majid; Housman, Douglas; Niyazov, Greg; Riaz, Nadeem; Lovelock, Michael; Spratt, Daniel E; Erinjeri, Joseph P

2013-01-01

To investigate the feasibility and dosimetric improvements of a novel technique to temporarily displace critical structures in the pelvis and abdomen from tumor during high-dose radiotherapy. Between 2010 and 2012, 11 patients received high-dose image-guided intensity-modulated radiotherapy with temporary organ displacement (TOD) at our institution. In all cases, imaging revealed tumor abutting critical structures. An all-purpose drainage catheter was introduced between the gross tumor volume (GTV) and critical organs at risk (OAR) and infused with normal saline (NS) containing 5-10% iohexol. Radiation planning was performed with the displaced OARs and positional reproducibility was confirmed with cone-beam CT (CBCT). Patients were treated within 36 hours of catheter placement. Radiation plans were re-optimized using pre-TOD OARs to the same prescription and dosimetrically compared with post-TOD plans. A two-tailed permutation test was performed on each dosimetric measure. The bowel/rectum was displaced in six patients and kidney in four patients. One patient was excluded due to poor visualization of the OAR; thus 10 patients were analyzed. A mean of 229 ml (range, 80–1000) of NS 5-10% iohexol infusion resulted in OAR mean displacement of 17.5 mm (range, 7–32). The median dose prescribed was 2400 cGy in one fraction (range, 2100–3000 in 3 fractions). The mean GTV D min and PTV D min pre- and post-bowel TOD IG-IMRT dosimetry significantly increased from 1473 cGy to 2086 cGy (p=0.015) and 714 cGy to 1214 cGy (p=0.021), respectively. TOD increased mean PTV D95 by 27.14% of prescription (p=0.014) while the PTV D05 decreased by 9.2% (p=0.011). TOD of the bowel resulted in a 39% decrease in mean bowel D max (p=0.008) confirmed by CBCT. TOD of the kidney significantly decreased mean kidney dose and D max by 25% (0.022). TOD was well tolerated, reproducible, and facilitated dose escalation to previously radioresistant tumors abutting critical structures while

Deep inspiration breath-hold radiotherapy for lung cancer: impact on image quality and registration uncertainty in cone beam CT image guidance

DEFF Research Database (Denmark)

Josipovic, Mirjana; Persson, Gitte F; Bangsgaard, Jens Peter

2016-01-01

OBJECTIVE: We investigated the impact of deep inspiration breath-hold (DIBH) and tumour baseline shifts on image quality and registration uncertainty in image-guided DIBH radiotherapy (RT) for locally advanced lung cancer. METHODS: Patients treated with daily cone beam CT (CBCT)-guided free...... for the craniocaudal direction in FB, where it was >3 mm. On the 31st fraction, the intraobserver uncertainty increased compared with the second fraction. This increase was more pronounced in FB. Image quality scores improved in DIBH compared with FB for all parameters in all patients. Simulated tumour baseline shifts...... ≤2 mm did not affect the CBCT image quality considerably. CONCLUSION: DIBH CBCT improved image quality and reduced registration uncertainty in the craniocaudal direction in image-guided RT of locally advanced lung cancer. Baseline shifts ≤2 mm in DIBH during CBCT acquisition did not affect image...

Navigator channel adaptation to reconstruct three dimensional heart volumes from two dimensional radiotherapy planning data

International Nuclear Information System (INIS)

Ng, Angela; Nguyen, Thao-Nguyen; Moseley, Joanne L; Hodgson, David C; Sharpe, Michael B; Brock, Kristy K

2012-01-01

Biologically-based models that utilize 3D radiation dosimetry data to estimate the risk of late cardiac effects could have significant utility for planning radiotherapy in young patients. A major challenge arises from having only 2D treatment planning data for patients with long-term follow-up. In this study, we evaluate the accuracy of an advanced deformable image registration (DIR) and navigator channels (NC) adaptation technique to reconstruct 3D heart volumes from 2D radiotherapy planning images for Hodgkin's Lymphoma (HL) patients. Planning CT images were obtained for 50 HL patients who underwent mediastinal radiotherapy. Twelve image sets (6 male, 6 female) were used to construct a male and a female population heart model, which was registered to 23 HL 'Reference' patients' CT images using a DIR algorithm, MORFEUS. This generated a series of population-to-Reference patient specific 3D deformation maps. The technique was independently tested on 15 additional 'Test' patients by reconstructing their 3D heart volumes using 2D digitally reconstructed radiographs (DRR). The technique involved: 1) identifying a matching Reference patient for each Test patient using thorax measurements, 2) placement of six NCs on matching Reference and Test patients' DRRs to capture differences in significant heart curvatures, 3) adapting the population-to-Reference patient-specific deformation maps to generate population-to-Test patient-specific deformation maps using linear and bilinear interpolation methods, 4) applying population-to-Test patient specific deformation to the population model to reconstruct Test-patient specific 3D heart models. The percentage volume overlap between the NC-adapted reconstruction and actual Test patient's true heart volume was calculated using the Dice coefficient. The average Dice coefficient expressed as a percentage between the NC-adapted and actual Test model was 89.4 ± 2.8%. The modified NC adaptation

A multi-institution evaluation of deformable image registration algorithms for automatic organ delineation in adaptive head and neck radiotherapy

International Nuclear Information System (INIS)

Hardcastle, Nicholas; Kumar, Prashant; Oechsner, Markus; Richter, Anne; Song, Shiyu; Myers, Michael; Polat, Bülent; Bzdusek, Karl; Tomé, Wolfgang A; Cannon, Donald M; Brouwer, Charlotte L; Wittendorp, Paul WH; Dogan, Nesrin; Guckenberger, Matthias; Allaire, Stéphane; Mallya, Yogish

2012-01-01

Adaptive Radiotherapy aims to identify anatomical deviations during a radiotherapy course and modify the treatment plan to maintain treatment objectives. This requires regions of interest (ROIs) to be defined using the most recent imaging data. This study investigates the clinical utility of using deformable image registration (DIR) to automatically propagate ROIs. Target (GTV) and organ-at-risk (OAR) ROIs were non-rigidly propagated from a planning CT scan to a per-treatment CT scan for 22 patients. Propagated ROIs were quantitatively compared with expert physician-drawn ROIs on the per-treatment scan using Dice scores and mean slicewise Hausdorff distances, and center of mass distances for GTVs. The propagated ROIs were qualitatively examined by experts and scored based on their clinical utility. Good agreement between the DIR-propagated ROIs and expert-drawn ROIs was observed based on the metrics used. 94% of all ROIs generated using DIR were scored as being clinically useful, requiring minimal or no edits. However, 27% (12/44) of the GTVs required major edits. DIR was successfully used on 22 patients to propagate target and OAR structures for ART with good anatomical agreement for OARs. It is recommended that propagated target structures be thoroughly reviewed by the treating physician

The ViewRay system: magnetic resonance-guided and controlled radiotherapy.

Science.gov (United States)

Mutic, Sasa; Dempsey, James F

2014-07-01

A description of the first commercially available magnetic resonance imaging (MRI)-guided radiation therapy (RT) system is provided. The system consists of a split 0.35-T MR scanner straddling 3 (60)Co heads mounted on a ring gantry, each head equipped with independent doubly focused multileaf collimators. The MR and RT systems share a common isocenter, enabling simultaneous and continuous MRI during RT delivery. An on-couch adaptive RT treatment-planning system and integrated MRI-guided RT control system allow for rapid adaptive planning and beam delivery control based on the visualization of soft tissues. Treatment of patients with this system commenced at Washington University in January 2014. Copyright © 2014 Elsevier Inc. All rights reserved.

Adaptive radiotherapy in muscle invasive urinary bladder cancer - An effective method to reduce the irradiated bowel volume

International Nuclear Information System (INIS)

Tuomikoski, Laura; Collan, Juhani; Keyrilaeinen, Jani; Visapaeae, Harri; Saarilahti, Kauko; Tenhunen, Mikko

2011-01-01

Background and purpose: To evaluate the benefits of adaptive radiotherapy for bladder cancer in decreasing irradiation of small bowel. Material and methods: Five patients with muscle invasive bladder cancer received adaptive radiotherapy to a total dose of 55.8-65 Gy with daily cone-beam computed tomography scanning. The whole bladder was treated to 45-50.4 Gy, followed by a partial bladder boost. The plan of the day was chosen from 3 to 4 pre-planned treatment plans according to the visible extent of bladder wall in cone-beam computed tomography images. Dose volume histograms for intestinal cavity volumes were constructed and compared with corresponding histograms calculated for conventional non-adaptive radiotherapy with single treatment plan of 2 cm CTV-PTV margins. CTV dose coverage in adaptive treatment technique was compared with CTV dose coverage in conventional radiotherapy. Results: The average volume of intestinal cavity receiving ≥45 Gy was reduced from 335 ± 106 cm 3 to 180 ± 113 cm 3 (1SD). The maximum volume of intestinal cavity spared at 45 Gy on a single patient was 240 cm 3 , while the minimum volume was 65 cm 3 . The corresponding reduction in average intestinal cavity volume receiving ≥45 Gy calculated for the whole bladder treatment only was 66 ± 36 cm 3 . CTV dose coverage was improved on two out of five patients and decreased on three patients. Conclusions: Adaptive radiotherapy considerably reduces dose to the small bowel, while maintaining the dose coverage of CTV at similar level when compared to the conventional treatment technique.

Adaptive radiotherapy for head and neck cancer—Dosimetric results from a prospective clinical trial

International Nuclear Information System (INIS)

Schwartz, David L.; Garden, Adam S.; Shah, Shalin J.; Chronowski, Gregory; Sejpal, Samir; Rosenthal, David I.; Chen, Yipei; Zhang, Yongbin; Zhang, Lifei; Wong, Pei-Fong; Garcia, John A.; Kian Ang, K.; Dong, Lei

2013-01-01

Purpose: To conduct a clinical trial evaluating adaptive head and neck radiotherapy (ART). Methods: Patients with locally advanced oropharyngeal cancer were prospectively enrolled. Daily CT-guided setup and deformable image registration permitted mapping of dose to avoidance structures and CTVs. We compared four planning scenarios: (1) original IMRT plan aligned daily to marked isocenter (BB); (2) original plan aligned daily to bone (IGRT); (3) IGRT with one adaptive replan (ART1); and (4) actual treatment received by each study patient (IGRT with one or two adaptive replans, ART2). Results: All 22 study patients underwent one replan (ART1); eight patients had two replans (ART2). ART1 reduced mean dose to contralateral parotid by 0.6 Gy or 2.8% (paired t-test; p = 0.003) and ipsilateral parotid by 1.3 Gy (3.9%) (p = 0.002) over the IGRT alone. ART2 further reduced the mean contralateral parotid dose by 0.8 Gy or 3.8% (p = 0.026) and ipsilateral parotid by 4.1 Gy or 9% (p = 0.001). ART significantly reduced integral body dose. Conclusions: This pilot trial suggests that head and neck ART dosimetrically outperforms IMRT. IGRT that leverages conventional PTV margins does not improve dosimetry. One properly timed replan delivers the majority of achievable dosimetric improvement. The clinical impact of ART must be confirmed by future trials

MR-CT registration using a Ni-Ti prostate stent in image-guided radiotherapy of prostate cancer.

Science.gov (United States)

Korsager, Anne Sofie; Carl, Jesper; Østergaard, Lasse Riis

2013-06-01

In image-guided radiotherapy of prostate cancer defining the clinical target volume often relies on magnetic resonance (MR). The task of transferring the clinical target volume from MR to standard planning computed tomography (CT) is not trivial due to prostate mobility. In this paper, an automatic local registration approach is proposed based on a newly developed removable Ni-Ti prostate stent. The registration uses the voxel similarity measure mutual information in a two-step approach where the pelvic bones are used to establish an initial registration for the local registration. In a phantom study, the accuracy was measured to 0.97 mm and visual inspection showed accurate registration of all 30 data sets. The consistency of the registration was examined where translation and rotation displacements yield a rotation error of 0.41° ± 0.45° and a translation error of 1.67 ± 2.24 mm. This study demonstrated the feasibility for an automatic local MR-CT registration using the prostate stent.

Helical tomo-therapy in the anal canal cancer: dosimetric comparison with conformal radiotherapy with intensity modulation and classical conformal radiotherapy

International Nuclear Information System (INIS)

Ozsahin, M.; Ugurluer, G.; Ballerini, G.; Letenneur, G.; Zouhair, A.; Mirimanoff, R.O.

2009-01-01

A dosimetry comparison was made between helical tomo-therapy, I.M.R.T. and classical conformal three dimensional radiotherapy for twelve first patients that received a image guided radiotherapy, the toxicity was tackled with a minimum follow-up of fourteen months. In conclusion, the CT-guided radiotherapy allows to save organs at risks superior to I.M.R.T. and conformal radiotherapy and a best homogeneity in the target volume. the toxicity is moderated and the break time is limited. (N.C.)

Prostate image-guided radiotherapy by megavolt cone-beam CT

International Nuclear Information System (INIS)

Zucca, Sergio; Carau, Barbara; Solla, Ignazio; Garibaldi, Elisabetta; Farace, Paolo; Lay, Giancarlo; Meleddu, Gianfranco; Gabriele, Pietro

2011-01-01

To test megavolt cone-beam CT (MV-CBCT) in order to evaluate setup errors in prostate radiotherapy. The setup of 9 patients was verified weekly by electronic portal imaging (EPI) and MV-CBCT, both performed in the same treatment session. EPI were compared with digitally reconstructed radiographies (DRRs). MV-CBCTs were matched to simulation CTs by manual registration based on bone markers (BMR), by manual registration based on soft tissues (STR) - rectum, bladder, and seminal vesicles - and by automatic registration (AR) performed by a mutual information algorithm. Shifts were evaluated along the three main axes: anteroposterior (AP), craniocaudal (CC), and laterolateral (LL). Finally, in 4 additional patients showing intraprostatic calcifications, the calcification mismatch error was used to evaluate the three MV-CBCT matching methods. A total of 50 pairs of orthogonal EPIs and 50 MV-CBCTs were analyzed. Assuming an overall tolerance of 2 mm, no significant differences were observed comparing EPI vs BMR in any axis. A significant difference (p < 0.001) was observed along the AP axis comparing EPI vs AR and EPI vs STR. On the calcification data set (22 measures), the calcification mismatch along the AP direction was significantly lower (p < 0.05) after STR than after BMR or AR. Bone markers were not an effective surrogate of the target position and significant differences were observed comparing EPI or BMR vs STR, supporting the assessment of soft tissue position by MVCBs to verify and correct patient setup in prostate radiotherapy. (orig.)

Prostate image-guided radiotherapy by megavolt cone-beam CT

Energy Technology Data Exchange (ETDEWEB)

Zucca, Sergio; Carau, Barbara; Solla, Ignazio; Garibaldi, Elisabetta; Farace, Paolo; Lay, Giancarlo; Meleddu, Gianfranco; Gabriele, Pietro [Regional Oncological Hospital, Cagliari (Italy). Dept. of Radiooncology

2011-08-15

To test megavolt cone-beam CT (MV-CBCT) in order to evaluate setup errors in prostate radiotherapy. The setup of 9 patients was verified weekly by electronic portal imaging (EPI) and MV-CBCT, both performed in the same treatment session. EPI were compared with digitally reconstructed radiographies (DRRs). MV-CBCTs were matched to simulation CTs by manual registration based on bone markers (BMR), by manual registration based on soft tissues (STR) - rectum, bladder, and seminal vesicles - and by automatic registration (AR) performed by a mutual information algorithm. Shifts were evaluated along the three main axes: anteroposterior (AP), craniocaudal (CC), and laterolateral (LL). Finally, in 4 additional patients showing intraprostatic calcifications, the calcification mismatch error was used to evaluate the three MV-CBCT matching methods. A total of 50 pairs of orthogonal EPIs and 50 MV-CBCTs were analyzed. Assuming an overall tolerance of 2 mm, no significant differences were observed comparing EPI vs BMR in any axis. A significant difference (p < 0.001) was observed along the AP axis comparing EPI vs AR and EPI vs STR. On the calcification data set (22 measures), the calcification mismatch along the AP direction was significantly lower (p < 0.05) after STR than after BMR or AR. Bone markers were not an effective surrogate of the target position and significant differences were observed comparing EPI or BMR vs STR, supporting the assessment of soft tissue position by MVCBs to verify and correct patient setup in prostate radiotherapy. (orig.)

WE-FG-206-08: Pulmonary Functional Imaging Biomarkers of NSCLC to Guide and Optimize Functional Lung Avoidance Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Sheikh, Khadija; Capaldi, Dante PI; Parraga, Grace [Robarts Research Institute (Canada); Hoover, Douglas A; Palma, David A [Department of Medical Biophysics, Department of Oncology, The University of Western Ontario, London (Canada); Yaremko, Brian P [Department of Oncology, The University of Western Ontario, London (Canada)

2016-06-15

Purpose: Functional lung avoidance radiotherapy promises optimized therapy planning by minimizing dose to well-functioning lung and maximizing dose to the rest of the lung. Patients with NSCLC commonly present with co-morbid COPD and heterogeneously distributed ventilation abnormalities stemming from emphysema, airways disease, and tumour burden. We hypothesized that pulmonary functional imaging methods may be used to optimize radiotherapy plans to avoid regions of well-functioning lung and significantly improve outcomes like quality-of-life and survival. To ascertain the utility of functional lung avoidance therapy in clinical practice, we measured COPD phenotypes in NSCLC patients enrolled in a randomized-controlled-clinical-trial prior to curative intent therapy. Methods: Thirty stage IIIA/IIIB NSCLC patients provided written informed consent to a randomized-controlled-clinical-trial ( http://clinicaltrials.gov/ct2/show/NCT02002052 ) comparing outcomes in patients randomized to standard or image-guided radiotherapy. Hyperpolarized noble gas MRI ventilation-defect-percent (VDP) (Kirby et al, Acad Radiol, 2012) as well as CT-emphysema measurements were determined. Patients were stratified based on quantitative imaging evidence of ventilation-defects and emphysema into two subgroups: 1) tumour-specific ventilation defects only (TSD), and, 2) tumour-specific and other ventilation defects with and without emphysema (TSD{sub VE}). Receiver-operating-characteristic (ROC) curves were used to characterize the performance of clinical measures as predictors of the presence of non-tumour specific ventilation defects. Results: Twenty-one out of thirty subjects (70%) had non-tumour specific ventilation defects (TSD{sub VE}) and nine subjects had ONLY tumour-specific defects (TSD). Subjects in the TSD{sub VE} group had significantly greater smoking-history (p=.006) and airflow obstruction (FEV{sub 1}/FVC) (p=.001). ROC analysis demonstrated an 87% classification rate for

Analysis of Magnetic Resonance Image Signal Fluctuations Acquired During MR-Guided Radiotherapy.

Science.gov (United States)

Breto, Adrian L; Padgett, Kyle R; Ford, John C; Kwon, Deukwoo; Chang, Channing; Fuss, Martin; Stoyanova, Radka; Mellon, Eric A

2018-03-28

Magnetic resonance-guided radiotherapy (MRgRT) is a new and evolving treatment modality that allows unprecedented visualization of the tumor and surrounding anatomy. MRgRT includes daily 3D magnetic resonance imaging (MRI) for setup and rapidly repeated near real-time MRI scans during treatment for target tracking. One of the more exciting potential benefits of MRgRT is the ability to analyze serial MRIs to monitor treatment response or predict outcomes. A typical radiation treatment (RT) over the span of 10-15 minutes on the MRIdian system (ViewRay, Cleveland, OH) yields thousands of "cine" images, each acquired in 250 ms. This unique data allows for a glimpse in image intensity changes during RT delivery. In this report, we analyze cine images from a single fraction RT of a glioblastoma patient on the ViewRay platform in order to characterize the dynamic signal changes occurring during RT therapy. The individual frames in the cines were saved into DICOM format and read into an MIM image analysis platform (MIM Software, Cleveland, OH) as a time series. The three possible states of the three Cobalt-60 radiation sources-OFF, READY, and ON-were also recorded. An in-house Java plugin for MIM was created in order to perform principal component analysis (PCA) on each of the datasets. The analysis resulted in first PC, related to monotonous signal increase over the course of the treatment fraction. We found several distortion patterns in the data that we postulate result from the perturbation of the magnetic field due to the moving metal parts in the platform while treatment was being administered. The largest variations were detected when all Cobalt-60 sources were OFF. During this phase of the treatment, the gantry and multi-leaf collimators (MLCs) are moving. Conversely, when all Cobalt-60 sources were in the ON position, the image signal fluctuations were minimal, relating to very little mechanical motion. At this phase, the gantry, the MLCs, and sources are fixed

MRI-based treatment plan simulation and adaptation for ion radiotherapy using a classification-based approach

International Nuclear Information System (INIS)

Rank, Christopher M; Tremmel, Christoph; Hünemohr, Nora; Nagel, Armin M; Jäkel, Oliver; Greilich, Steffen

2013-01-01

In order to benefit from the highly conformal irradiation of tumors in ion radiotherapy, sophisticated treatment planning and simulation are required. The purpose of this study was to investigate the potential of MRI for ion radiotherapy treatment plan simulation and adaptation using a classification-based approach. Firstly, a voxelwise tissue classification was applied to derive pseudo CT numbers from MR images using up to 8 contrasts. Appropriate MR sequences and parameters were evaluated in cross-validation studies of three phantoms. Secondly, ion radiotherapy treatment plans were optimized using both MRI-based pseudo CT and reference CT and recalculated on reference CT. Finally, a target shift was simulated and a treatment plan adapted to the shift was optimized on a pseudo CT and compared to reference CT optimizations without plan adaptation. The derivation of pseudo CT values led to mean absolute errors in the range of 81 - 95 HU. Most significant deviations appeared at borders between air and different tissue classes and originated from partial volume effects. Simulations of ion radiotherapy treatment plans using pseudo CT for optimization revealed only small underdosages in distal regions of a target volume with deviations of the mean dose of PTV between 1.4 - 3.1% compared to reference CT optimizations. A plan adapted to the target volume shift and optimized on the pseudo CT exhibited a comparable target dose coverage as a non-adapted plan optimized on a reference CT. We were able to show that a MRI-based derivation of pseudo CT values using a purely statistical classification approach is feasible although no physical relationship exists. Large errors appeared at compact bone classes and came from an imperfect distinction of bones and other tissue types in MRI. In simulations of treatment plans, it was demonstrated that these deviations are comparable to uncertainties of a target volume shift of 2 mm in two directions indicating that especially

TH-E-202-02: The Use of Hypoxia PET Imaging for Radiotherapy

International Nuclear Information System (INIS)

Humm, J.

2016-01-01

PET/CT is a very important imaging tool in the management of oncology patients. PET/CT has been applied for treatment planning and response evaluation in radiation therapy. This educational session will discuss: Pitfalls and remedies in PET/CT imaging for RT planning The use of hypoxia PET imaging for radiotherapy PET for tumor response evaluation The first presentation will address the issue of mis-registration between the CT and PET images in the thorax and the abdomen. We will discuss the challenges of respiratory gating and introduce an average CT technique to improve the registration for dose calculation and image-guidance in radiation therapy. The second presentation will discuss the use of hypoxia PET Imaging for radiation therapy. We will discuss various hypoxia radiotracers, the choice of clinical acquisition protocol (in particular a single late static acquisition versus a dynamic acquisition), and the compartmental modeling with different transfer rate constants explained. We will demonstrate applications of hypoxia imaging for dose escalation/de-escalation in clinical trials. The last presentation will discuss the use of PET/CT for tumor response evaluation. We will discuss anatomic response assessment vs. metabolic response assessment, visual evaluation and semi-quantitative evaluation, and limitations of current PET/CT assessment. We will summarize clinical trials using PET response in guiding adaptive radiotherapy. Finally, we will summarize recent advancements in PET/CT radiomics and non-FDG PET tracers for response assessment. Learning Objectives: Identify the causes of mis-registration of CT and PET images in PET/CT, and review the strategies to remedy the issue. Understand the basics of PET imaging of tumor hypoxia (radiotracers, how PET measures the hypoxia selective uptake, imaging protocols, applications in chemo-radiation therapy). Understand the basics of dynamic PET imaging, compartmental modeling and parametric images. Understand the

TH-E-202-02: The Use of Hypoxia PET Imaging for Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Humm, J. [Memorial Sloan-Kettering Cancer Center (United States)

2016-06-15

PET/CT is a very important imaging tool in the management of oncology patients. PET/CT has been applied for treatment planning and response evaluation in radiation therapy. This educational session will discuss: Pitfalls and remedies in PET/CT imaging for RT planning The use of hypoxia PET imaging for radiotherapy PET for tumor response evaluation The first presentation will address the issue of mis-registration between the CT and PET images in the thorax and the abdomen. We will discuss the challenges of respiratory gating and introduce an average CT technique to improve the registration for dose calculation and image-guidance in radiation therapy. The second presentation will discuss the use of hypoxia PET Imaging for radiation therapy. We will discuss various hypoxia radiotracers, the choice of clinical acquisition protocol (in particular a single late static acquisition versus a dynamic acquisition), and the compartmental modeling with different transfer rate constants explained. We will demonstrate applications of hypoxia imaging for dose escalation/de-escalation in clinical trials. The last presentation will discuss the use of PET/CT for tumor response evaluation. We will discuss anatomic response assessment vs. metabolic response assessment, visual evaluation and semi-quantitative evaluation, and limitations of current PET/CT assessment. We will summarize clinical trials using PET response in guiding adaptive radiotherapy. Finally, we will summarize recent advancements in PET/CT radiomics and non-FDG PET tracers for response assessment. Learning Objectives: Identify the causes of mis-registration of CT and PET images in PET/CT, and review the strategies to remedy the issue. Understand the basics of PET imaging of tumor hypoxia (radiotracers, how PET measures the hypoxia selective uptake, imaging protocols, applications in chemo-radiation therapy). Understand the basics of dynamic PET imaging, compartmental modeling and parametric images. Understand the

Magnetic Resonance Imaging and conformal radiotherapy: Characterization of MRI alone simulation for conformal radiotherapy. Development and evaluation of an automatic volumes of interest segmentation tool for prostate cancer radiotherapy

International Nuclear Information System (INIS)

Pasquier, David

2006-01-01

Radiotherapy is a curative treatment of malignant tumours. Radiotherapy techniques considerably evolved last years with the increasing integration of medical images in conformal radiotherapy. This technique makes it possible to elaborate a complex ballistics conforming to target volume and sparing healthy tissues. The examination currently used to delineate volumes of interest is Computed Tomography (CT), on account of its geometrical precision and the information that it provides on electronic densities needed to dose calculation. Magnetic Resonance Imaging (MRI) ensures a more precise delineation of target volumes in many locations, such as pelvis and brain. For pelvic tumours, the use of MRI needs image registration, which complicates treatment planning and poses the problem of the lack of in vivo standard method of validation. The obstacles in the use of MRI alone in treatment planning were evaluated. Neither geometrical distortion linked with the system and the patient nor the lack of information on electronic densities represent stumbling obstacles. Distortion remained low even in edge of large field of view on modern machines. The assignment of electronic densities to bone structures and soft tissues in MR images permitted to obtain equivalent dosimetry to that carried out on the original CT, with a good reproducibility and homogeneous distribution within target volume. The assignment of electronic densities could not be carried out using 20 MV photons and suitable ballistics. The development of Image Guided Radiotherapy could facilitate the use of MRI alone in treatment planning. Target volumes and organ at risk delineation is a time consuming task in radiotherapy planning. We took part in the development and evaluated a method of automatic and semi automatic delineation of volumes of interest from MRI images for prostate cancer radiotherapy. For prostate and organ at risk automatic delineation an organ model-based method and a seeded region growing method

Assessment of contrast enhanced respiration managed cone-beam CT for image guided radiotherapy of intrahepatic tumors

International Nuclear Information System (INIS)

Jensen, Nikolaj K. G.; Stewart, Errol; Lock, Michael; Fisher, Barbara; Kozak, Roman; Chen, Jeff; Lee, Ting-Yim; Wong, Eugene

2014-01-01

Purpose: Contrast enhancement and respiration management are widely used during image acquisition for radiotherapy treatment planning of liver tumors along with respiration management at the treatment unit. However, neither respiration management nor intravenous contrast is commonly used during cone-beam CT (CBCT) image acquisition for alignment prior to radiotherapy. In this study, the authors investigate the potential gains of injecting an iodinated contrast agent in combination with respiration management during CBCT acquisition for liver tumor radiotherapy. Methods: Five rabbits with implanted liver tumors were subjected to CBCT with and without motion management and contrast injection. The acquired CBCT images were registered to the planning CT to determine alignment accuracy and dosimetric impact. The authors developed a simulation tool for simulating contrast-enhanced CBCT images from dynamic contrast enhanced CT imaging (DCE-CT) to determine optimal contrast injection protocols. The tool was validated against contrast-enhanced CBCT of the rabbit subjects and was used for five human patients diagnosed with hepatocellular carcinoma. Results: In the rabbit experiment, when neither motion management nor contrast was used, tumor centroid misalignment between planning image and CBCT was 9.2 mm. This was reduced to 2.8 mm when both techniques were employed. Tumors were not visualized in clinical CBCT images of human subjects. Simulated contrast-enhanced CBCT was found to improve tumor contrast in all subjects. Different patients were found to require different contrast injections to maximize tumor contrast. Conclusions: Based on the authors’ animal study, respiration managed contrast enhanced CBCT improves IGRT significantly. Contrast enhanced CBCT benefits from patient specific tracer kinetics determined from DCE-CT

Assessment of contrast enhanced respiration managed cone-beam CT for image guided radiotherapy of intrahepatic tumors

Energy Technology Data Exchange (ETDEWEB)

Jensen, Nikolaj K. G., E-mail: nkyj@regionsjaelland.dk [Physics and Engineering, London Regional Cancer Program, London, Ontario N6A3K7 (Canada); Stewart, Errol [Radiology, St. Joseph' s Health Care, London, Ontario N6A 4V2 (Canada); Imaging Research Lab, Robarts Research Institute, London, Ontario N6A 5B7 (Canada); Imaging Program, Lawson Health Research Institute, London, Ontario N6C 2R5 (Canada); Lock, Michael; Fisher, Barbara [Radiation Oncology, London Regional Cancer Program, London, Ontario N6A3K7 (Canada); Department of Oncology, University of Western Ontario, London, Ontario N6A 4L6 (Canada); Kozak, Roman [Radiology, St. Joseph' s Health Care, London, Ontario N6A 4V2 (Canada); Chen, Jeff [Physics and Engineering, London Regional Cancer Program, London, Ontario N6A3K7 (Canada); Department of Oncology, University of Western Ontario, London, Ontario N6A 4L6 (Canada); Department of Medical Biophysics, University of Western Ontario, London, Ontario N6A 5C1 (Canada); Lee, Ting-Yim [Radiology, St. Joseph' s Health Care, London, Ontario N6A 4V2 (Canada); Imaging Research Lab, Robarts Research Institute, London, Ontario N6A 5B7 (Canada); Imaging Program, Lawson Health Research Institute, London, Ontario N6C 2R5 (Canada); Department of Oncology, University of Western Ontario, London, Ontario N6A 4L6 (Canada); Department of Medical Biophysics, University of Western Ontario, London, Ontario N6A 5C1 (Canada); Wong, Eugene [Physics and Engineering, London Regional Cancer Program, London, Ontario N6A3K7 (Canada); Department of Oncology, University of Western Ontario, London, Ontario N6A 4L6 (Canada); Department of Medical Biophysics, University of Western Ontario, London, Ontario N6A 5C1 (Canada); Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7 (Canada)

2014-05-15

Purpose: Contrast enhancement and respiration management are widely used during image acquisition for radiotherapy treatment planning of liver tumors along with respiration management at the treatment unit. However, neither respiration management nor intravenous contrast is commonly used during cone-beam CT (CBCT) image acquisition for alignment prior to radiotherapy. In this study, the authors investigate the potential gains of injecting an iodinated contrast agent in combination with respiration management during CBCT acquisition for liver tumor radiotherapy. Methods: Five rabbits with implanted liver tumors were subjected to CBCT with and without motion management and contrast injection. The acquired CBCT images were registered to the planning CT to determine alignment accuracy and dosimetric impact. The authors developed a simulation tool for simulating contrast-enhanced CBCT images from dynamic contrast enhanced CT imaging (DCE-CT) to determine optimal contrast injection protocols. The tool was validated against contrast-enhanced CBCT of the rabbit subjects and was used for five human patients diagnosed with hepatocellular carcinoma. Results: In the rabbit experiment, when neither motion management nor contrast was used, tumor centroid misalignment between planning image and CBCT was 9.2 mm. This was reduced to 2.8 mm when both techniques were employed. Tumors were not visualized in clinical CBCT images of human subjects. Simulated contrast-enhanced CBCT was found to improve tumor contrast in all subjects. Different patients were found to require different contrast injections to maximize tumor contrast. Conclusions: Based on the authors’ animal study, respiration managed contrast enhanced CBCT improves IGRT significantly. Contrast enhanced CBCT benefits from patient specific tracer kinetics determined from DCE-CT.

Patient positioning and immobilization in static and dynamic adaptive radiotherapy: an integral part of IGRT

International Nuclear Information System (INIS)

Oinam, Arun S.

2016-01-01

Radiotherapy treatment deals with different varieties of treatment procedures depending on type and stages of tumors. These treatments are grossly classified into palliative curative treatment. Immobilizations used in this treatment are designed with respect to this classification as well as the techniques. With the improvements in imaging technology used in Radiotherapy, patient position set up margin can be reduced as compared to the conventional radiotherapy. Still immobilization in patient position setup has been an integral part of Image Guided Radiotherapy (lGRT) and Stereotactic Radio Surgery (SRS) and Radiotherapy (SRT). Immobilization used in this technique should produce a minimum attenuation of radiation beam as well as positioning comfort and this will enhance the reproducibility for the daily position setup and immobilize the patient during the treatment. Advanced dose delivery technique like Intensity Modulated Radiotherapy (IMRT) and Volumetric Modulated Arc Radiotherapy (VMAT) can do differential dose sculpting around and inside the irregular shape different target volumes while minimizing the dose to the surrounding organs at risk. A small positional error may produce the mistreatment of target and exposure of organs at risk beyond the acceptable dose limits. Such a potential positional error can be reduced if different varieties of good immobilizing devices are properly utilized. The immobilization used in the treatment of Head and Neck and Cranial tumor can produce better immobilization as compared to abdominal and pelvic tumors which are forced to move by the inability to control movements of lung and heart as well as the very large flabby tissues which are attached skeleton bones

Radiotherapy in prostate cancer. Innovative techniques and current controversies

International Nuclear Information System (INIS)

Geinitz, Hans

2015-01-01

Examines in detail the role of innovative radiation techniques in the management of prostate cancer, including IMRT, IGRT, BART, and modern brachytherapy. Explores a range of current controversies in patient treatment. Intended for both radiation oncologists and urologists. Radiation treatment is rapidly evolving owing to the coordinated research of physicists, engineers, computer and imaging specialists, and physicians. Today, the arsenal of ''high-precision'' or ''targeted'' radiotherapy includes multimodal imaging, in vivo dosimetry, Monte Carlo techniques for dose planning, patient immobilization techniques, intensity-modulated radiotherapy (IMRT), image-guided radiotherapy (IGRT), biologically adapted radiotherapy (BART), quality assurance methods, novel methods of brachytherapy, and, at the far end of the scale, particle beam radiotherapy using protons and carbon ions. These approaches are like pieces of a puzzle that need to be put together to provide the prostate cancer patient with high-level optimized radiation treatment. This book examines in detail the role of the above-mentioned innovative radiation techniques in the management of prostate cancer. In addition, a variety of current controversies regarding treatment are carefully explored, including whether prophylactic treatment of the pelvic lymphatics is essential, the magnitude of the effect of dose escalation, whether a benefit accrues from hypofractionation, and what evidence exists for the superiority of protons or heavy ions. Radiotherapy in Prostate Cancer: Innovative Techniques and Current Controversies is intended for both radiation oncologists and urologists with an interest in the up-to-date capabilities of modern radiation oncology for the treatment of prostate cancer.

Imaging for cancer therapy

International Nuclear Information System (INIS)

Schlegel, W.

2005-01-01

During the last three decades, 3D imaging with X-ray computerized tomography (CT) and magnetic resonance imaging (MRI) were introduced to characterize tumour morphology for improved delineation of target volumes. At present, the time has come to also start the assessment and correction of the temporal alterations of the target volume. This is leading to 'image guided radiotherapy' (IGRT), which is characterized by the integration of 2D and 3D imaging modalities into the radiotherapy workflow. The vision is to detect deformations and motion between radiotherapy fractions (inter-fractional IGRT) and during beam delivery (intra fractional IGRT). Considering these changes and correcting for them either by gating or tracking of the irradiation beam is leading a step further to 'time adapted radiotherapy' (ART). Many institutions are currently addressing this technical challenge, with the goal of implementing IGRT and ART into radiotherapy as a faster, safer and more efficient treatment technique. Another innovation, which is currently coming up is 'biological adaptive radiotherapy'. The background for this approach is the fact, that the old hypothesis of radiotherapy assuming that the tumor consists of homogenous tissue and therefore a homogeneous dose distribution has to be delivered to the target can no longer be sustained. It is known today, that a tumor may consist of various subvolumes with different radiobiological properties. New methods are currently being developed to characterize these properties more appropriately, e.g. by functional and molecular imaging using new tracers for Positron Emission Tomography (PET) and by functional magnetic resonance imaging (fMRI). The challenge in radiotherapy is to develop concepts to include and integrate this information into radiotherapy planning and beam delivery, first by extending the morphological image content towards a biological planning target volume including subvolumes of different radiosensitivity, and second by

SU-E-J-254: Utility of Pinnacle Dynamic Planning Module Utilizing Deformable Image Registration in Adaptive Radiotherapy

International Nuclear Information System (INIS)

Jani, S

2014-01-01

Purpose For certain highly conformal treatment techniques, changes in patient anatomy due to weight loss and/or tumor shrinkage can result in significant changes in dose distribution. Recently, the Pinnacle treatment planning system added a Dynamic Planning module utilizing Deformable Image Registration (DIR). The objective of this study was to evaluate the effectiveness of this software in adapting to altered anatomy and adjusting treatment plans to account for it. Methods We simulated significant tumor response by changing patient thickness and altered chin positions using a commercially-available head and neck (H and N) phantom. In addition, we studied 23 CT image sets of fifteen (15) patients with H and N tumors and eight (8) patients with prostate cancer. In each case, we applied deformable image registration through Dynamic Planning module of our Pinnacle Treatment Planning System. The dose distribution of the original CT image set was compared to the newly computed dose without altering any treatment parameter. Result was a dose if we did not adjust the plan to reflect anatomical changes. Results For the H and N phantom, a tumor response of up to 3.5 cm was correctly deformed by the Pinnacle Dynamic module. Recomputed isodose contours on new anatomies were within 1 mm of the expected distribution. The Pinnacle system configuration allowed dose computations resulting from original plans on new anatomies without leaving the planning system. Original and new doses were available side-by-side with both CT image sets. Based on DIR, about 75% of H and N patients (11/15) required a re-plan using new anatomy. Among prostate patients, the DIR predicted near-correct bladder volume in 62% of the patients (5/8). Conclusions The Dynamic Planning module of the Pinnacle system proved to be an accurate and useful tool in our ability to adapt to changes in patient anatomy during a course of radiotherapy

Automatic prostate localization on cone-beam CT scans for high precision image-guided radiotherapy

International Nuclear Information System (INIS)

Smitsmans, Monique H.P.; Bois, Josien de; Sonke, Jan-Jakob; Betgen, Anja; Zijp, Lambert J.; Jaffray, David A.; Lebesque, Joos V.; Herk, Marcel van

2005-01-01

Purpose: Previously, we developed an automatic three-dimensional gray-value registration (GR) method for fast prostate localization that could be used during online or offline image-guided radiotherapy. The method was tested on conventional computed tomography (CT) scans. In this study, the performance of the algorithm to localize the prostate on cone-beam CT (CBCT) scans acquired on the treatment machine was evaluated. Methods and Materials: Five to 17 CBCT scans of 32 prostate cancer patients (332 scans in total) were used. For 18 patients (190 CBCT scans), the CBCT scans were acquired with a collimated field of view (FOV) (craniocaudal). This procedure improved the image quality considerably. The prostate (i.e., prostate plus seminal vesicles) in each CBCT scan was registered to the prostate in the planning CT scan by automatic 3D gray-value registration (normal GR) starting from a registration on the bony anatomy. When these failed, registrations were repeated with a fixed rotation point locked at the prostate apex (fixed apex GR). Registrations were visually assessed in 3D by one observer with the help of an expansion (by 3.6 mm) of the delineated prostate contours of the planning CT scan. The percentage of successfully registered cases was determined from the combined normal and fixed apex GR assessment results. The error in gray-value registration for both registration methods was determined from the position of one clearly defined calcification in the prostate gland (9 patients, 71 successful registrations). Results: The percentage of successfully registered CBCT scans that were acquired with a collimated FOV was about 10% higher than for CBCT scans that were acquired with an uncollimated FOV. For CBCT scans that were acquired with a collimated FOV, the percentage of successfully registered cases improved from 65%, when only normal GR was applied, to 83% when the results of normal and fixed apex GR were combined. Gray-value registration mainly failed (or

Development of an ultrasmall C-band linear accelerator guide for a four-dimensional image-guided radiotherapy system with a gimbaled x-ray head.

Science.gov (United States)

Kamino, Yuichiro; Miura, Sadao; Kokubo, Masaki; Yamashita, Ichiro; Hirai, Etsuro; Hiraoka, Masahiro; Ishikawa, Junzo

2007-05-01

We are developing a four-dimensional image-guided radiotherapy system with a gimbaled x-ray head. It is capable of pursuing irradiation and delivering irradiation precisely with the help of an agile moving x-ray head on the gimbals. Requirements for the accelerator guide were established, system design was developed, and detailed design was conducted. An accelerator guide was manufactured and basic beam performance and leakage radiation from the accelerator guide were evaluated at a low pulse repetition rate. The accelerator guide including the electron gun is 38 cm long and weighs about 10 kg. The length of the accelerating structure is 24.4 cm. The accelerating structure is a standing wave type and is composed of the axial-coupled injector section and the side-coupled acceleration cavity section. The injector section is composed of one prebuncher cavity, one buncher cavity, one side-coupled half cavity, and two axial coupling cavities. The acceleration cavity section is composed of eight side-coupled nose reentrant cavities and eight coupling cavities. The electron gun is a diode-type gun with a cerium hexaboride (CeB6) direct heating cathode. The accelerator guide can be operated without any magnetic focusing device. Output beam current was 75 mA with a transmission efficiency of 58%, and the average energy was 5.24 MeV. Beam energy was distributed from 4.95 to 5.6 MeV. The beam profile, measured 88 mm from the beam output hole on the axis of the accelerator guide, was 0.7 mm X 0.9 mm full width at half maximum (FWHM) width. The beam loading line was 5.925 (MeV)-Ib (mA) X 0.00808 (MeV/mA), where Ib is output beam current. The maximum radiation leakage of the accelerator guide at 100 cm from the axis of the accelerator guide was calculated as 0.33 cGy/min at the rated x-ray output of 500 cGy/min from the measured value. This leakage requires no radiation shielding for the accelerator guide itself per IEC 60601-2-1.

Feasibility of Tomotherapy-based image-guided radiotherapy to reduce aspiration risk in patients with non-laryngeal and non-pharyngeal head and neck cancer.

Directory of Open Access Journals (Sweden)

Nam P Nguyen

Full Text Available PURPOSE: The study aims to assess the feasibility of Tomotherapy-based image-guided radiotherapy (IGRT to reduce the aspiration risk in patients with non-laryngeal and non-hypopharyngeal cancer. A retrospective review of 48 patients undergoing radiation for non-laryngeal and non-hypopharyngeal head and neck cancers was conducted. All patients had a modified barium swallow (MBS prior to treatment, which was repeated one month following radiotherapy. Mean middle and inferior pharyngeal dose was recorded and correlated with the MBS results to determine aspiration risk. RESULTS: Mean pharyngeal dose was 23.2 Gy for the whole group. Two patients (4.2% developed trace aspiration following radiotherapy which resolved with swallowing therapy. At a median follow-up of 19 months (1-48 months, all patients were able to resume normal oral feeding without aspiration. CONCLUSION AND CLINICAL RELEVANCE: IGRT may reduce the aspiration risk by decreasing the mean pharyngeal dose in the presence of large cervical lymph nodes. Further prospective studies with IGRT should be performed in patients with non-laryngeal and non-hypopharyngeal head and neck cancers to verify this hypothesis.

Image-guided intensity-modulated radiotherapy for prostate cancer: Dose constraints for the anterior rectal wall to minimize rectal toxicity

Energy Technology Data Exchange (ETDEWEB)

Peterson, Jennifer L., E-mail: peterson.jennifer2@mayo.edu [Department of Radiation Oncology, Mayo Clinic Florida, Jacksonville, FL (United States); Buskirk, Steven J. [Department of Radiation Oncology, Mayo Clinic Florida, Jacksonville, FL (United States); Heckman, Michael G.; Diehl, Nancy N. [Section of Biostatistics, Mayo Clinic Florida, Jacksonville, FL (United States); Bernard, Johnny R. [Section of Biostatistics, Mayo Clinic Florida, Jacksonville, FL (United States); Department of Radiation Oncology, Southern Ohio Medical Center, Portsmouth, OH (United States); Tzou, Katherine S.; Casale, Henry E.; Bellefontaine, Louis P.; Serago, Christopher; Kim, Siyong; Vallow, Laura A.; Daugherty, Larry C.; Ko, Stephen J. [Department of Radiation Oncology, Mayo Clinic Florida, Jacksonville, FL (United States)

2014-04-01

Rectal adverse events (AEs) are a major concern with definitive radiotherapy (RT) treatment for prostate cancer. The anterior rectal wall is at the greatest risk of injury as it lies closest to the target volume and receives the highest dose of RT. This study evaluated the absolute volume of anterior rectal wall receiving a high dose to identify potential ideal dose constraints that can minimize rectal AEs. A total of 111 consecutive patients with Stage T1c to T3a N0 M0 prostate cancer who underwent image-guided intensity-modulated RT at our institution were included. AEs were graded according to the Common Terminology Criteria for Adverse Events, version 4.0. The volume of anterior rectal wall receiving 5 to 80 Gy in 2.5-Gy increments was determined. Multivariable Cox regression models were used to identify cut points in these volumes that led to an increased risk of early and late rectal AEs. Early AEs occurred in most patients (88%); however, relatively few of them (13%) were grade ≥2. At 5 years, the cumulative incidence of late rectal AEs was 37%, with only 5% being grade ≥2. For almost all RT doses, we identified a threshold of irradiated absolute volume of anterior rectal wall above which there was at least a trend toward a significantly higher rate of AEs. Most strikingly, patients with more than 1.29, 0.73, or 0.45 cm{sup 3} of anterior rectal wall exposed to radiation doses of 67.5, 70, or 72.5 Gy, respectively, had a significantly increased risk of late AEs (relative risks [RR]: 2.18 to 2.72; p ≤ 0.041) and of grade ≥ 2 early AEs (RR: 6.36 to 6.48; p = 0.004). Our study provides evidence that definitive image-guided intensity-modulated radiotherapy (IG-IMRT) for prostate cancer is well tolerated and also identifies dose thresholds for the absolute volume of anterior rectal wall above which patients are at greater risk of early and late complications.

Image-guided intensity-modulated radiotherapy for prostate cancer: Dose constraints for the anterior rectal wall to minimize rectal toxicity

International Nuclear Information System (INIS)

Peterson, Jennifer L.; Buskirk, Steven J.; Heckman, Michael G.; Diehl, Nancy N.; Bernard, Johnny R.; Tzou, Katherine S.; Casale, Henry E.; Bellefontaine, Louis P.; Serago, Christopher; Kim, Siyong; Vallow, Laura A.; Daugherty, Larry C.; Ko, Stephen J.

2014-01-01

Rectal adverse events (AEs) are a major concern with definitive radiotherapy (RT) treatment for prostate cancer. The anterior rectal wall is at the greatest risk of injury as it lies closest to the target volume and receives the highest dose of RT. This study evaluated the absolute volume of anterior rectal wall receiving a high dose to identify potential ideal dose constraints that can minimize rectal AEs. A total of 111 consecutive patients with Stage T1c to T3a N0 M0 prostate cancer who underwent image-guided intensity-modulated RT at our institution were included. AEs were graded according to the Common Terminology Criteria for Adverse Events, version 4.0. The volume of anterior rectal wall receiving 5 to 80 Gy in 2.5-Gy increments was determined. Multivariable Cox regression models were used to identify cut points in these volumes that led to an increased risk of early and late rectal AEs. Early AEs occurred in most patients (88%); however, relatively few of them (13%) were grade ≥2. At 5 years, the cumulative incidence of late rectal AEs was 37%, with only 5% being grade ≥2. For almost all RT doses, we identified a threshold of irradiated absolute volume of anterior rectal wall above which there was at least a trend toward a significantly higher rate of AEs. Most strikingly, patients with more than 1.29, 0.73, or 0.45 cm 3 of anterior rectal wall exposed to radiation doses of 67.5, 70, or 72.5 Gy, respectively, had a significantly increased risk of late AEs (relative risks [RR]: 2.18 to 2.72; p ≤ 0.041) and of grade ≥ 2 early AEs (RR: 6.36 to 6.48; p = 0.004). Our study provides evidence that definitive image-guided intensity-modulated radiotherapy (IG-IMRT) for prostate cancer is well tolerated and also identifies dose thresholds for the absolute volume of anterior rectal wall above which patients are at greater risk of early and late complications

A study of image-guided radiotherapy of bladder cancer based on lipiodol injection in the bladder wall

International Nuclear Information System (INIS)

Soendergaard, Jimmi; Muren, Ludvig Paul; Elstroem, Ulrik Vindelev; Grau, Cai; Hoeyer, Morten; Oerding Olsen, Kasper

2010-01-01

Purpose. We have tested a procedure of focal injection of the contrast medium Lipiodol as a fiducial marker for image-guided boost of the tumor in bladder cancer radiotherapy (RT). In this study, we have evaluated the feasibility and the safety of the method as well as the inter- and intra-fraction shift of the bladder tumor. Materials and methods. Five patients with muscle invasive urinary bladder cancer were included in the study. Lipiodol was injected during flexible cystoscopy into the submucosa of the bladder wall at the periphery of the tumor or the post resection tumor-bed. Cone-beam CT (CBCT) scans were acquired daily throughout the course of RT. Results. Lipiodol demarcation of the bladder tumor was feasible and safe with only a minimum of side effects related to the procedure. The Lipiodol spots were visible on CT and CBCT scans for the duration of the RT course. More than half of all the treatment fractions required a geometric shift of 5 mm or more to match on the Lipiodol spots. The mean intra-fraction shift (3D) of the tumor was 3 mm, largest in the anterior-posterior and cranial-caudal directions. Conclusion. This study demonstrates that Lipiodol can be injected into the bladder mucosa and subsequently visualized on CT and CBCT as a fiducial marker. The relatively large inter-fraction shifts in the positions of Lipiodol spots compared to the intra-fraction movement indicates that image-guided RT based on radio-opaque markers is important for RT of the bladder cancer tumor.

SU-F-J-57: Effectiveness of Daily CT-Based Three-Dimensional Image Guided and Adaptive Proton Therapy

Energy Technology Data Exchange (ETDEWEB)

Moriya, S [University of Tsukuba, Tsukuba, Ibaraki (Japan); National Cancer Center, Kashiwa, Chiba (Japan); Tachibana, H; Hotta, K; Baba, H; Kohno, R; Akimoto, T [National Cancer Center, Kashiwa, Chiba (Japan); Nakamura, N [National Cancer Center Hospital East, Kashiwa, Chiba (Japan); Miyakawa, S; Kurosawa, T [Komazawa University, Setagaya, Tokyo (Japan)

2016-06-15

Purpose: Daily CT-based three-dimensional image-guided and adaptive (CTIGRT-ART) proton therapy system was designed and developed. We also evaluated the effectiveness of the CTIGRT-ART. Methods: Retrospective analysis was performed in three lung cancer patients: Proton treatment planning was performed using CT image datasets acquired by Toshiba Aquilion ONE. Planning target volume and surrounding organs were contoured by a well-trained radiation oncologist. Dose distribution was optimized using 180-deg. and 270-deg. two fields in passive scattering proton therapy. Well commissioned Simplified Monte Carlo algorithm was used as dose calculation engine. Daily consecutive CT image datasets was acquired by an in-room CT (Toshiba Aquilion LB). In our in-house program, two image registrations for bone and tumor were performed to shift the isocenter using treatment CT image dataset. Subsequently, dose recalculation was performed after the shift of the isocenter. When the dose distribution after the tumor registration exhibits change of dosimetric parameter of CTV D90% compared to the initial plan, an additional process of was performed that the range shifter thickness was optimized. Dose distribution with CTV D90% for the bone registration, the tumor registration only and adaptive plan with the tumor registration was compared to the initial plan. Results: In the bone registration, tumor dose coverage was decreased by 16% on average (Maximum: 56%). The tumor registration shows better coverage than the bone registration, however the coverage was also decreased by 9% (Maximum: 22%) The adaptive plan shows similar dose coverage of the tumor (Average: 2%, Maximum: 7%). Conclusion: There is a high possibility that only image registration for bone and tumor may reduce tumor coverage. Thus, our proposed methodology of image guidance and adaptive planning using the range adaptation after tumor registration would be effective for proton therapy. This research is partially supported

Feasibility study on 3D image reconstruction from 2D orthogonal cine-MRI for MRI-guided radiotherapy.

Science.gov (United States)

Paganelli, Chiara; Lee, Danny; Kipritidis, John; Whelan, Brendan; Greer, Peter B; Baroni, Guido; Riboldi, Marco; Keall, Paul

2018-02-11

In-room MRI is a promising image guidance strategy in external beam radiotherapy to acquire volumetric information for moving targets. However, limitations in spatio-temporal resolution led several authors to use 2D orthogonal images for guidance. The aim of this work is to present a method to concurrently compensate for non-rigid tumour motion and provide an approach for 3D reconstruction from 2D orthogonal cine-MRI slices for MRI-guided treatments. Free-breathing sagittal/coronal interleaved 2D cine-MRI were acquired in addition to a pre-treatment 3D volume in two patients. We performed deformable image registration (DIR) between cine-MRI slices and corresponding slices in the pre-treatment 3D volume. Based on an extrapolation of the interleaved 2D motion fields, the 3D motion field was estimated and used to warp the pre-treatment volume. Due to the lack of a ground truth for patients, the method was validated on a digital 4D lung phantom. On the phantom, the 3D reconstruction method was able to compensate for tumour motion and compared favourably to the results of previously adopted strategies. The difference in the 3D motion fields between the phantom and the extrapolated motion was 0.4 ± 0.3 mm for tumour and 0.8 ± 1.5 mm for whole anatomy, demonstrating feasibility of performing a 3D volumetric reconstruction directly from 2D orthogonal cine-MRI slices. Application of the method to patient data confirmed the feasibility of utilizing this method in real world scenarios. Preliminary results on phantom and patient cases confirm the feasibility of the proposed approach in an MRI-guided scenario, especially for non-rigid tumour motion compensation. © 2018 The Royal Australian and New Zealand College of Radiologists.

What is the value of Image guidance in external beam radiotherapy?

International Nuclear Information System (INIS)

Kron, Tomas

2010-01-01

Full text: Image guided radiation therapy (lGRT) has become available in many radiotherapy centres in Australia. It is intuitive that frequent imaging of the patient with a modality that identifies the target directly at the time of treatment delivery should benefit patients. However, TGRT is also associated with increased cost for equipment, associated training, quality assurance and imaging time. The Trans Tasman Radiation Oncology Group (TROG) has been contracted by the Australian Commonwealth Department of Health and Ageing (DoHA) to investigate a framework that could be applied to establish a cost/utility assessment of IGRT. The present work aims to develop a study that can test this for daily image guidance of prostate cancer patients. Approach Thirty intermediate risk prostate cancer patients treated at ten or more radiotherapy centres in Australia will be invited to participate. Their treatment as per local practice will not be modified; however two additional treatment plans will be created with margins that would reflect a typical margin appropriate for a treatment delivery with and without daily image guidance. Patients will be stratified for volumetric versus planar orthogonal imaging and for IMRT or conformal approaches. The outcome will be a comparison of dose volume histograms for critical structures based on equal target coverage in all plans.

Multi-centre experience of implementing image-guided intensity-modulated radiotherapy using the TomoTherapy platform

International Nuclear Information System (INIS)

Dean, J.C.; Tudor, G.S.J.; Mott, J.H.; Dunlop, P.R.; Morris, S.L.; Harron, E.C.; Christian, J.A.; Sanghera, P.; Elsworthy, M.; Burnet, N.G.

2013-01-01

Use of image guided (IG) intensity modulated radiotherapy (IMRT) is increasing, and helical tomotherapy provides an effective, integrated solution. Practical experience of implementation, shared at a recent UK TomoTherapy Users' meeting, may help centres introducing these techniques using TomoTherapy or other platforms. Seven centres participated, with data shared from 6, varying from 2500 - 4800 new patients per year. Case selection of patients “most likely” to benefit from IG-IMRT was managed in all centres by multi-professional groups comprising clinical oncologists, physicists, treatment planners and radiographers. Radical treatments ranged from 94% to 100%. The proportions of tumour types varied substantially: head and neck: range 0%–100% (mean of centres 50%), prostate: 3%–96% (mean of centres 28%). Head and neck cases were considered most likely to benefit from IMRT, prostate cases from IGRT, or IG-IMRT if pelvic nodes were being treated. IMRT was also selected for complex target volumes, to avoid field junctions, for technical treatment difficulties, and retreatments. Across the centres, every patient was imaged every day, with positional correction before treatment. In one centre, for prostate patients including pelvic treatment, the pelvis was also imaged weekly. All centres had designed a ‘ramp up’ of patient numbers, which was similar in 5. One centre, treating 96% prostate patients, started with 3 and increased to 36 patients per day within 3 months. The variation in case mix implies wide applicability of IG-IMRT. Daily on-line IGRT with IMRT can be routinely implemented into busy departments

Acute Toxicity in Definitive Versus Postprostatectomy Image-Guided Radiotherapy for Prostate Cancer

International Nuclear Information System (INIS)

Cheng, Jonathan C.; Schultheiss, Timothy E.; Nguyen, Khanh H.; Wong, Jeffrey Y.C.

2008-01-01

Purpose: To assess the incidence of acute gastrointestinal (GI) and genitourinary (GU) injury and the dose-volume response in patients with clinically localized prostate cancer treated with image-guided radiotherapy using helical tomotherapy. Methods and Materials: Between November 2004 and March 2007, 146 consecutive patients with localized prostate cancer were treated with helical tomotherapy at the City of Hope Medical Center. Of the 146 patients, 70 had undergone prostatectomy. Acute GI and GU toxicities were evaluated using the Radiation Therapy Oncology Group/European Organization for Research and Cancer of Medical scoring system. Events were scored for patients developing Grade 2 or greater morbidity within 90 days after the end of radiotherapy (RT). The dosimetric parameters included the minimal dose received by the highest 10%, 20%, 50%, 80%, and 90% of the target volume, the mean rectal dose, minimal rectal dose, maximal rectal dose, and the volume receiving ≥45, ≥65, and ≥70 Gy. These variables, plus the status of radical prostatectomy, hormonal therapy, RT techniques, and medical conditions, were included in a multivariate logistic regression analysis. A goodness-of-fit evaluation was done using the Hosmer-Lemeshow statistic. Results: A dose-response function for acute GI toxicity was elicited. The acute GI Grade 2 or greater toxicity was lower in the definitive RT group than in the postoperative RT group (25% vs. 41%, p <0.05). Acute GU Grade 2 or greater toxicity was comparable between the two groups. No grade 3 or greater complications were observed. No dosimetric variable was significant for GU toxicity. For acute GI toxicity, the significant dosimetric parameters were the minimal dose received by 10%, 20%, and 50% of the target volume and the mean rectal dose; the most predictive parameter was the minimal dose received by 10% of the target volume. The dose-modifying factor was 1.2 for radical prostatectomy. Conclusion: The results of our

Vaginal dose de-escalation in image guided adaptive brachytherapy for locally advanced cervical cancer

DEFF Research Database (Denmark)

Mohamed, Sandy; Lindegaard, Jacob Christian; de Leeuw, Astrid A C

2016-01-01

Purpose Vaginal stenosis is a major problem following radiotherapy in cervical cancer. We investigated a new dose planning strategy for vaginal dose de-escalation (VDD). Materials and methods Fifty consecutive locally advanced cervical cancer patients without lower or middle vaginal involvement...... at diagnosis from 3 institutions were analysed. External beam radiotherapy was combined with MRI-guided brachytherapy. VDD was obtained by decreasing dwell times in ovoid/ring and increasing dwell times in tandem/needles. The aim was to maintain the target dose (D90 of HR-CTV ⩾ 85 Gy EQD2) while reducing...... bladder and rectum (D2cm3) were reduced by 2 ± 2 Gy and 3 ± 2 Gy, respectively (p

Rectal dose variation during the course of image-guided radiation therapy of prostate cancer

International Nuclear Information System (INIS)

Chen Lili; Paskalev, Kamen; Xu Xiu; Zhu, Jennifer; Wang Lu; Price, Robert A.; Hu Wei; Feigenberg, Steven J.; Horwitz, Eric M.; Pollack, Alan; Charlie Ma, C.M.

2010-01-01

Background and purpose: To investigate the change in rectal dose during the treatment course for intensity-modulated radiotherapy (IMRT) of prostate cancer with image-guidance. Materials and methods: Twenty prostate cancer patients were recruited for this retrospective study. All patients have been treated with IMRT. For each patient, MR and CT images were fused for target and critical structure delineation. IMRT treatment planning was performed on the simulation CT images. Inter-fractional motion during the course of treatment was corrected using a CT-on-rails system. The rectum was outlined on both the original treatment plan and the subsequent daily CT images from the CT-on-rails by the same investigator. Dose distributions on these daily CT images were recalculated with the isocenter shifts relative to the simulation CT images using the leaf sequences/MUs based on the original treatment plan. The rectal doses from the subsequent daily CTs were compared with the original doses planned on the simulation CT using our clinical acceptance criteria. Results: Based on 20 patients with 139 daily CT sets, 28% of the subsequent treatment dose distributions did not meet our criterion of V 40 65 < 17%. The inter-fractional rectal volume variation is significant for some patients. Conclusions: Due to the large inter-fractional variation of the rectal volume, it is more favorable to plan prostate IMRT based on an empty rectum and deliver treatment to patients with an empty rectum. Over 70% of actual treatments showed better rectal doses than our clinical acceptance criteria. A significant fraction (27%) of the actual treatments would benefit from adaptive image-guided radiotherapy based on daily CT images.

Image-guided robotic surgery.

Science.gov (United States)

Marescaux, Jacques; Solerc, Luc

2004-06-01

Medical image processing leads to an improvement in patient care by guiding the surgical gesture. Three-dimensional models of patients that are generated from computed tomographic scans or magnetic resonance imaging allow improved surgical planning and surgical simulation that offers the opportunity for a surgeon to train the surgical gesture before performing it for real. These two preoperative steps can be used intra-operatively because of the development of augmented reality, which consists of superimposing the preoperative three-dimensional model of the patient onto the real intraoperative view. Augmented reality provides the surgeon with a view of the patient in transparency and can also guide the surgeon, thanks to the real-time tracking of surgical tools during the procedure. When adapted to robotic surgery, this tool tracking enables visual serving with the ability to automatically position and control surgical robotic arms in three dimensions. It is also now possible to filter physiologic movements such as breathing or the heart beat. In the future, by combining augmented reality and robotics, these image-guided robotic systems will enable automation of the surgical procedure, which will be the next revolution in surgery.

An automatic dose verification system for adaptive radiotherapy for helical tomotherapy

International Nuclear Information System (INIS)

Mo, Xiaohu; Chen, Mingli; Parnell, Donald; Olivera, Gustavo; Galmarini, Daniel; Lu, Weiguo

2014-01-01

Purpose: During a typical 5-7 week treatment of external beam radiotherapy, there are potential differences between planned patient's anatomy and positioning, such as patient weight loss, or treatment setup. The discrepancies between planned and delivered doses resulting from these differences could be significant, especially in IMRT where dose distributions tightly conforms to target volumes while avoiding organs-at-risk. We developed an automatic system to monitor delivered dose using daily imaging. Methods: For each treatment, a merged image is generated by registering the daily pre-treatment setup image and planning CT using treatment position information extracted from the Tomotherapy archive. The treatment dose is then computed on this merged image using our in-house convolution-superposition based dose calculator implemented on GPU. The deformation field between merged and planning CT is computed using the Morphon algorithm. The planning structures and treatment doses are subsequently warped for analysis and dose accumulation. All results are saved in DICOM format with private tags and organized in a database. Due to the overwhelming amount of information generated, a customizable tolerance system is used to flag potential treatment errors or significant anatomical changes. A web-based system and a DICOM-RT viewer were developed for reporting and reviewing the results. Results: More than 30 patients were analysed retrospectively. Our in-house dose calculator passed 97% gamma test evaluated with 2% dose difference and 2mm distance-to-agreement compared with Tomotherapy calculated dose, which is considered sufficient for adaptive radiotherapy purposes. Evaluation of the deformable registration through visual inspection showed acceptable and consistent results, except for cases with large or unrealistic deformation. Our automatic flagging system was able to catch significant patient setup errors or anatomical changes. Conclusions: We developed an automatic

Evaluation of deformable image registration for contour propagation between CT and cone-beam CT images in adaptive head and neck radiotherapy.

Science.gov (United States)

Li, X; Zhang, Y Y; Shi, Y H; Zhou, L H; Zhen, X

2016-04-29

Deformable image registration (DIR) is a critical technic in adaptive radiotherapy (ART) to propagate contours between planning computerized tomography (CT) images and treatment CT/Cone-beam CT (CBCT) image to account for organ deformation for treatment re-planning. To validate the ability and accuracy of DIR algorithms in organ at risk (OAR) contours mapping, seven intensity-based DIR strategies are tested on the planning CT and weekly CBCT images from six Head & Neck cancer patients who underwent a 6 ∼ 7 weeks intensity-modulated radiation therapy (IMRT). Three similarity metrics, i.e. the Dice similarity coefficient (DSC), the percentage error (PE) and the Hausdorff distance (HD), are employed to measure the agreement between the propagated contours and the physician delineated ground truths. It is found that the performance of all the evaluated DIR algorithms declines as the treatment proceeds. No statistically significant performance difference is observed between different DIR algorithms (p> 0.05), except for the double force demons (DFD) which yields the worst result in terms of DSC and PE. For the metric HD, all the DIR algorithms behaved unsatisfactorily with no statistically significant performance difference (p= 0.273). These findings suggested that special care should be taken when utilizing the intensity-based DIR algorithms involved in this study to deform OAR contours between CT and CBCT, especially for those organs with low contrast.

WE-AB-207A-08: BEST IN PHYSICS (IMAGING): Advanced Scatter Correction and Iterative Reconstruction for Improved Cone-Beam CT Imaging On the TrueBeam Radiotherapy Machine

Energy Technology Data Exchange (ETDEWEB)

Wang, A; Paysan, P; Brehm, M; Maslowski, A; Lehmann, M; Messmer, P; Munro, P; Yoon, S; Star-Lack, J; Seghers, D [Varian Medical Systems, Palo Alto, CA (United States)

2016-06-15

Purpose: To improve CBCT image quality for image-guided radiotherapy by applying advanced reconstruction algorithms to overcome scatter, noise, and artifact limitations Methods: CBCT is used extensively for patient setup in radiotherapy. However, image quality generally falls short of diagnostic CT, limiting soft-tissue based positioning and potential applications such as adaptive radiotherapy. The conventional TrueBeam CBCT reconstructor uses a basic scatter correction and FDK reconstruction, resulting in residual scatter artifacts, suboptimal image noise characteristics, and other artifacts like cone-beam artifacts. We have developed an advanced scatter correction that uses a finite-element solver (AcurosCTS) to model the behavior of photons as they pass (and scatter) through the object. Furthermore, iterative reconstruction is applied to the scatter-corrected projections, enforcing data consistency with statistical weighting and applying an edge-preserving image regularizer to reduce image noise. The combined algorithms have been implemented on a GPU. CBCT projections from clinically operating TrueBeam systems have been used to compare image quality between the conventional and improved reconstruction methods. Planning CT images of the same patients have also been compared. Results: The advanced scatter correction removes shading and inhomogeneity artifacts, reducing the scatter artifact from 99.5 HU to 13.7 HU in a typical pelvis case. Iterative reconstruction provides further benefit by reducing image noise and eliminating streak artifacts, thereby improving soft-tissue visualization. In a clinical head and pelvis CBCT, the noise was reduced by 43% and 48%, respectively, with no change in spatial resolution (assessed visually). Additional benefits include reduction of cone-beam artifacts and reduction of metal artifacts due to intrinsic downweighting of corrupted rays. Conclusion: The combination of an advanced scatter correction with iterative reconstruction

Characterization of Target Volume Changes During Breast Radiotherapy Using Implanted Fiducial Markers and Portal Imaging

International Nuclear Information System (INIS)

Harris, Emma J.; Donovan, Ellen M.; Yarnold, John R.; Coles, Charlotte E.; Evans, Philip M.

2009-01-01

Purpose: To determine target volume changes by using volume and shape analysis for patients receiving radiotherapy after breast conservation surgery and to compare different methods of automatically identifying changes in target volume, position, size, and shape during radiotherapy for use in adaptive radiotherapy. Methods and Materials: Eleven patients undergoing whole breast radiotherapy had fiducial markers sutured into the excision cavity at the time of surgery. Patients underwent imaging using computed tomography (for planning and at the end of treatment) and during treatment by using portal imaging. A marker volume (MV) was defined by using the measured marker positions. Changes in both individual marker positions and MVs were identified manually and using six automated similarity indices. Comparison of the two types of analysis (manual and automated) was undertaken to establish whether similarity indices can be used to automatically detect changes in target volumes. Results: Manual analysis showed that 3 patients had significant MV reduction. This analysis also showed significant changes between planning computed tomography and the start of treatment for 9 patients, including single and multiple marker movement, deformation (shape change), and rotation. Four of the six similarity indices were shown to be sensitive to the observed changes. Conclusions: Significant changes in size, shape, and position occur to the fiducial marker-defined volume. Four similarity indices can be used to identify these changes, and a protocol for their use in adaptive radiotherapy is suggested

Long-term outcomes from dose-escalated image-guided intensity-modulated radiotherapy with androgen deprivation: encouraging results for intermediate- and high-risk prostate cancer

Directory of Open Access Journals (Sweden)

Wilcox SW

2014-08-01

Full Text Available Shea W Wilcox,1,4 Noel J Aherne,2,4 Linus C Benjamin,1 Bosco Wu,1 Thomaz de Campos Silva,3 Craig S McLachlan,4 Michael J McKay,3,5 Andrew J Last,1 Thomas P Shakespeare1–4 1North Coast Cancer Institute, Port Macquarie, NSW, Australia; 2North Coast Cancer Institute, Coffs Harbour, NSW, Australia; 3North Coast Cancer Institute, Lismore, NSW, Australia; 4The University of New South Wales, Rural Clinical School, Sydney, NSW, Australia; 5The University of Sydney, Sydney, NSW, Australia Purpose: Dose-escalated (DE radiotherapy in the setting of localized prostate cancer has been shown to improve biochemical disease-free survival (bDFS in several studies. In the same group of patients, androgen deprivation therapy (ADT has been shown to confer a survival benefit when combined with radiotherapy doses of up to 70 Gy; however, there is currently little long-term data on patients who have received high-dose intensity-modulated radiotherapy (IMRT with ADT. We report the long-term outcomes in a large cohort of patients treated with the combination of DE image-guided IMRT (IG-IMRT and ADT. Methods and materials: Patients with localized prostate cancer were identified from a centralized database across an integrated cancer center. All patients received DE IG-IMRT, combined with ADT, and had a minimum follow up of 12 months post-radiotherapy. All relapse and toxicity data were collected prospectively. Actuarial bDFS, metastasis-free survival, prostate cancer-specific survival, and multivariate analyses were calculated using the SPSS v20.0 statistical package. Results: Seven hundred and eighty-two eligible patients were identified with a median follow up of 46 months. Overall, 4.3% of patients relapsed, 2.0% developed distant metastases, and 0.6% died from metastatic prostate cancer. At 5-years, bDFS was 88%, metastasis-free survival was 95%, and prostate cancer-specific survival was 98%. Five-year grade 2 genitourinary and gastrointestinal toxicity was 2

Determination of tolerances in the positioning of the treatment table from an image-guided system

International Nuclear Information System (INIS)

Perez Moreno, J. M.; Zucca Aparicio, D.; Fernandez leton, P.; Garcia Ruiz-Zorrilla, J.; Minanbres Moro, A.

2011-01-01

The use of techniques of image-guided radiotherapy (TGRT) aims to reduce the uncertainties associated with patient positioning. One of the techniques more recent development is the cone beam CT (CBCT), consisting of the acquisition of volumetric images of the patient by a detector integrated into the linear accelerator. By analyzing the results of all sessions of treatment to all patients in which the positioning has been carried out with image-guided system MV CBCT have been determined tolerance tables for translational coordinates of the table treatment based on pathology and immobilization system used. (Author)

Radiation therapy technology innovations applied to the treatment of head and neck patients: - Clinical results of Intensity Modulated Radiotherapy (IMRT), - Contribution of Image Guided Radiotherapy (IGRT) in the management of head and neck patients treated with IMRT

International Nuclear Information System (INIS)

Graff-Cailleaud, Pierre

2011-01-01

Numerous and exciting technological innovations were recently developed in radiotherapy. We aimed to assess benefits in two specific fields. 1) Clinical results of Intensity Modulated Radiotherapy (IMRT) applied to the treatment of Head and Neck (H and N) patients. The first study was a long-term mono-centric prospective registration of all H and N patients treated with IMRT in our institution. Locoregional control was excellent and toxicities limited. Recurrences were in-field. Dosimetric recommendations (parotids mean dose) were established. The second study assessed the impact of IMRT on health-related quality of life for H and N patients through a multicentric matched-pair comparison with conventional radiotherapy. Outstanding benefits were observed particularly in the fields of salivary dysfunction and oral discomfort. 2) Contribution of Image Guided Radiotherapy (IGRT) in the management of H and N patients treated with IMRT. The first study was a monitoring of delivered dose, using 3D dose recalculation from Megavoltage Cone-Beam CT (CBCT), as a quality assurance measure of a panel of H and N IMRT patients aligned with IGRT. Dosimetric consequences of anatomical changes were assessed. Contribution of color-coded MVCBCT dose-difference maps was studied. The aim of the second study was to quantify the inherent relative mobility between anatomic regions of the H and N area and to assess the dosimetric impact of several different matching procedures. Recommendations for the use of CBCT images in a daily practice were established. (author) [fr

MR-CT registration using a Ni-Ti prostate stent in image-guided radiotherapy of prostate cancer

International Nuclear Information System (INIS)

Korsager, Anne Sofie; Østergaard, Lasse Riis; Carl, Jesper

2013-01-01

Purpose: In image-guided radiotherapy of prostate cancer defining the clinical target volume often relies on magnetic resonance (MR). The task of transferring the clinical target volume from MR to standard planning computed tomography (CT) is not trivial due to prostate mobility. In this paper, an automatic local registration approach is proposed based on a newly developed removable Ni-Ti prostate stent.Methods: The registration uses the voxel similarity measure mutual information in a two-step approach where the pelvic bones are used to establish an initial registration for the local registration.Results: In a phantom study, the accuracy was measured to 0.97 mm and visual inspection showed accurate registration of all 30 data sets. The consistency of the registration was examined where translation and rotation displacements yield a rotation error of 0.41° ± 0.45° and a translation error of 1.67 ± 2.24 mm.Conclusions: This study demonstrated the feasibility for an automatic local MR-CT registration using the prostate stent.

MR-CT registration using a Ni-Ti prostate stent in image-guided radiotherapy of prostate cancer

Energy Technology Data Exchange (ETDEWEB)

Korsager, Anne Sofie; Ostergaard, Lasse Riis [Department of Health Science and Technology, Aalborg University, Aalborg 9220 (Denmark); Carl, Jesper [Department of Medical Physics, Oncology, Aalborg Hospital, Aalborg 9100 (Denmark)

2013-06-15

Purpose: In image-guided radiotherapy of prostate cancer defining the clinical target volume often relies on magnetic resonance (MR). The task of transferring the clinical target volume from MR to standard planning computed tomography (CT) is not trivial due to prostate mobility. In this paper, an automatic local registration approach is proposed based on a newly developed removable Ni-Ti prostate stent.Methods: The registration uses the voxel similarity measure mutual information in a two-step approach where the pelvic bones are used to establish an initial registration for the local registration.Results: In a phantom study, the accuracy was measured to 0.97 mm and visual inspection showed accurate registration of all 30 data sets. The consistency of the registration was examined where translation and rotation displacements yield a rotation error of 0.41 Degree-Sign {+-} 0.45 Degree-Sign and a translation error of 1.67 {+-} 2.24 mm.Conclusions: This study demonstrated the feasibility for an automatic local MR-CT registration using the prostate stent.

Adaptive optics and laser guide stars at Lick observatory

Energy Technology Data Exchange (ETDEWEB)

Brase, J.M. [Lawrence Livermore National Lab., CA (United States)

1994-11-15

For the past several years LLNL has been developing adaptive optics systems for correction of both atmospheric turbulence effects and thermal distortions in optics for high-power lasers. Our early work focused on adaptive optics for beam control in laser isotope separation and ground-based free electron lasers. We are currently developing innovative adaptive optics and laser systems for sodium laser guide star applications at the University of California`s Lick and Keck Observeratories. This talk will describe our adaptive optics technology and some of its applications in high-resolution imaging and beam control.

Adaptive radiotherapy using helical tomotherapy system

International Nuclear Information System (INIS)

Jeswani, Sam; Ruchala, Kenneth; Olivera, Gustavo; Mackie, T.R.

2008-01-01

As commonly known in the field, adaptive radiation therapy (ART) is the use of feedback to modify a radiotherapy treatment. There are numerous ways in which this feedback can be received and used, and this presentation will discuss some of the implementations of ART being investigated with a helical TomoTherapy system

Atlas-guided generation of pseudo-CT images for MRI-only and hybrid PET-MRI-guided radiotherapy treatment planning

DEFF Research Database (Denmark)

Arabi, H.; Koutsouvelis, N.; Rouzaud, M.

2016-01-01

Magnetic resonance imaging (MRI)-guided attenuation correction (AC) of positron emission tomography (PET) data and/or radiation therapy (RT) treatment planning is challenged by the lack of a direct link between MRI voxel intensities and electron density. Therefore, even if this is not a trivial t......-CT images from conventional Dixon MRI sequences with improved bone extraction accuracy. The approach is promising for potential use in PET AC and MRI-only or hybrid PET/MRI-guided RT treatment planning. © 2016 Institute of Physics and Engineering in Medicine.......Magnetic resonance imaging (MRI)-guided attenuation correction (AC) of positron emission tomography (PET) data and/or radiation therapy (RT) treatment planning is challenged by the lack of a direct link between MRI voxel intensities and electron density. Therefore, even if this is not a trivial...... the conventional MRI segmentation technique and a recently proposed multi-atlas approach. The clinical studies consisted of pelvic CT, PET and MRI scans of 12 patients with loco-regionally advanced rectal disease. In the first step, bone segmentation of the target image is optimized through local weighted atlas...

Radiotherapy in prostate cancer. Innovative techniques and current controversies

Energy Technology Data Exchange (ETDEWEB)

Geinitz, Hans [Krankenhaus der Barmherzigen Schwestern, Linz (Austria). Dept. of Radiation Oncology; Linz Univ. (Austria). Medical Faculty; Roach, Mack III [California Univ., San Francisco, CA (United States). Dept. of Radiation Oncology; Van As, Nicholas (ed.) [The Institute of Cancer Research, Sutton Surrey (United Kingdom)

2015-04-01

Examines in detail the role of innovative radiation techniques in the management of prostate cancer, including IMRT, IGRT, BART, and modern brachytherapy. Explores a range of current controversies in patient treatment. Intended for both radiation oncologists and urologists. Radiation treatment is rapidly evolving owing to the coordinated research of physicists, engineers, computer and imaging specialists, and physicians. Today, the arsenal of ''high-precision'' or ''targeted'' radiotherapy includes multimodal imaging, in vivo dosimetry, Monte Carlo techniques for dose planning, patient immobilization techniques, intensity-modulated radiotherapy (IMRT), image-guided radiotherapy (IGRT), biologically adapted radiotherapy (BART), quality assurance methods, novel methods of brachytherapy, and, at the far end of the scale, particle beam radiotherapy using protons and carbon ions. These approaches are like pieces of a puzzle that need to be put together to provide the prostate cancer patient with high-level optimized radiation treatment. This book examines in detail the role of the above-mentioned innovative radiation techniques in the management of prostate cancer. In addition, a variety of current controversies regarding treatment are carefully explored, including whether prophylactic treatment of the pelvic lymphatics is essential, the magnitude of the effect of dose escalation, whether a benefit accrues from hypofractionation, and what evidence exists for the superiority of protons or heavy ions. Radiotherapy in Prostate Cancer: Innovative Techniques and Current Controversies is intended for both radiation oncologists and urologists with an interest in the up-to-date capabilities of modern radiation oncology for the treatment of prostate cancer.

TH-AB-202-04: Auto-Adaptive Margin Generation for MLC-Tracked Radiotherapy

International Nuclear Information System (INIS)

Glitzner, M; Lagendijk, J; Raaymakers, B; Crijns, S; Fast, M; Nill, S; Oelfke, U; Denis de Senneville, B

2016-01-01

Purpose: To develop an auto-adaptive margin generator for MLC tracking. The generator is able to estimate errors arising in image guided radiotherapy, particularly on an MR-Linac, which depend on the latencies of machine and image processing, as well as on patient motion characteristics. From the estimated error distribution, a segment margin is generated, able to compensate errors up to a user-defined confidence. Method: In every tracking control cycle (TCC, 40ms), the desired aperture D(t) is compared to the actual aperture A(t), a delayed and imperfect representation of D(t). Thus an error e(t)=A(T)-D(T) is measured every TCC. Applying kernel-density-estimation (KDE), the cumulative distribution (CDF) of e(t) is estimated. With CDF-confidence limits, upper and lower error limits are extracted for motion axes along and perpendicular leaf-travel direction and applied as margins. To test the dosimetric impact, two representative motion traces were extracted from fast liver-MRI (10Hz). The traces were applied onto a 4D-motion platform and continuously tracked by an Elekta Agility 160 MLC using an artificially imposed tracking delay. Gafchromic film was used to detect dose exposition for static, tracked, and error-compensated tracking cases. The margin generator was parameterized to cover 90% of all tracking errors. Dosimetric impact was rated by calculating the ratio between underexposed points (>5% underdosage) to the total number of points inside FWHM of static exposure. Results: Without imposing adaptive margins, tracking experiments showed a ratio of underexposed points of 17.5% and 14.3% for two motion cases with imaging delays of 200ms and 300ms, respectively. Activating the margin generated yielded total suppression (<1%) of underdosed points. Conclusion: We showed that auto-adaptive error compensation using machine error statistics is possible for MLC tracking. The error compensation margins are calculated on-line, without the need of assuming motion or

TH-AB-202-04: Auto-Adaptive Margin Generation for MLC-Tracked Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Glitzner, M; Lagendijk, J; Raaymakers, B; Crijns, S [University Medical Center Utrecht, Utrecht (Netherlands); Fast, M; Nill, S; Oelfke, U [The Institute of Cancer Research, London (United Kingdom); Denis de Senneville, B [University Medical Center Utrecht, Utrecht (Netherlands); IMB, UMR 5251 CNRS/University of Bordeaux, Talence, FR (France)

2016-06-15

Purpose: To develop an auto-adaptive margin generator for MLC tracking. The generator is able to estimate errors arising in image guided radiotherapy, particularly on an MR-Linac, which depend on the latencies of machine and image processing, as well as on patient motion characteristics. From the estimated error distribution, a segment margin is generated, able to compensate errors up to a user-defined confidence. Method: In every tracking control cycle (TCC, 40ms), the desired aperture D(t) is compared to the actual aperture A(t), a delayed and imperfect representation of D(t). Thus an error e(t)=A(T)-D(T) is measured every TCC. Applying kernel-density-estimation (KDE), the cumulative distribution (CDF) of e(t) is estimated. With CDF-confidence limits, upper and lower error limits are extracted for motion axes along and perpendicular leaf-travel direction and applied as margins. To test the dosimetric impact, two representative motion traces were extracted from fast liver-MRI (10Hz). The traces were applied onto a 4D-motion platform and continuously tracked by an Elekta Agility 160 MLC using an artificially imposed tracking delay. Gafchromic film was used to detect dose exposition for static, tracked, and error-compensated tracking cases. The margin generator was parameterized to cover 90% of all tracking errors. Dosimetric impact was rated by calculating the ratio between underexposed points (>5% underdosage) to the total number of points inside FWHM of static exposure. Results: Without imposing adaptive margins, tracking experiments showed a ratio of underexposed points of 17.5% and 14.3% for two motion cases with imaging delays of 200ms and 300ms, respectively. Activating the margin generated yielded total suppression (<1%) of underdosed points. Conclusion: We showed that auto-adaptive error compensation using machine error statistics is possible for MLC tracking. The error compensation margins are calculated on-line, without the need of assuming motion or

SU-F-J-110: MRI-Guided Single-Session Simulation, Online Adaptation, and Treatment

International Nuclear Information System (INIS)

Hill, P; Geurts, M; Mittauer, K; Bayouth, J

2016-01-01

Purpose: To develop a combined simulation and treatment workflow for MRI-guided radiation therapy using the ViewRay treatment planning and delivery system. Methods: Several features of the ViewRay MRIdian planning and treatment workflows are used to simulate and treat patients that require emergent radiotherapy. A simple “pre-plan” is created on diagnostic imaging retrieved from radiology PACS, where conformal fields are created to target a volume defined by a physician based on review of the diagnostic images and chart notes. After initial consult in radiation oncology, the patient is brought to the treatment room, immobilized, and imaged in treatment position with a volumetric MR. While the patient rests on the table, the pre-plan is applied to the treatment planning MR and dose is calculated in the treatment geometry. After physician review, modification of the plan may include updating the target definition, redefining fields, or re-balancing beam weights. Once an acceptable treatment plan is finalized and approved, the patient is treated. Results: Careful preparation and judicious choices in the online planning process allow conformal treatment plans to be created and delivered in a single, thirty-minute session. Several advantages have been identified using this process as compared to conventional urgent CT simulation and delivery. Efficiency gains are notable, as physicians appreciate the predictable time commitment and patient waiting time for treatment is decreased. MR guidance in a treatment position offers both enhanced contrast for target delineation and reduction of setup uncertainties. The MRIdian system tools designed for adaptive radiotherapy are particularly useful, enabling plan changes to be made in minutes. Finally, the resulting plans, typically 6 conformal beams, are delivered as quickly as more conventional AP/PA beam arrangements with comparatively superior dose distributions. Conclusion: The ViewRay treatment planning software and

Complexity and accuracy of image registration methods in SPECT-guided radiation therapy

Energy Technology Data Exchange (ETDEWEB)

Yin, L S; Duzenli, C; Moiseenko, V [Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC, V6T 1Z1 (Canada); Tang, L; Hamarneh, G [Computing Science, Simon Fraser University, 9400 TASC1, Burnaby, BC, V5A 1S6 (Canada); Gill, B [Medical Physics, Vancouver Cancer Centre, BC Cancer Agency, 600 West 10th Ave, Vancouver, BC, V5Z 4E6 (Canada); Celler, A; Shcherbinin, S [Department of Radiology, University of British Columbia, 828 West 10th Ave, Vancouver, BC, V5Z 1L8 (Canada); Fua, T F; Thompson, A; Sheehan, F [Radiation Oncology, Vancouver Cancer Centre, BC Cancer Agency, 600 West 10th Ave, Vancouver, BC, V5Z 4E6 (Canada); Liu, M [Radiation Oncology, Fraser Valley Cancer Centre, BC Cancer Agency, 13750 9th Ave, Surrey, BC, V3V 1Z2 (Canada)], E-mail: lyin@bccancer.bc.ca

2010-01-07

The use of functional imaging in radiotherapy treatment (RT) planning requires accurate co-registration of functional imaging scans to CT scans. We evaluated six methods of image registration for use in SPECT-guided radiotherapy treatment planning. Methods varied in complexity from 3D affine transform based on control points to diffeomorphic demons and level set non-rigid registration. Ten lung cancer patients underwent perfusion SPECT-scans prior to their radiotherapy. CT images from a hybrid SPECT/CT scanner were registered to a planning CT, and then the same transformation was applied to the SPECT images. According to registration evaluation measures computed based on the intensity difference between the registered CT images or based on target registration error, non-rigid registrations provided a higher degree of accuracy than rigid methods. However, due to the irregularities in some of the obtained deformation fields, warping the SPECT using these fields may result in unacceptable changes to the SPECT intensity distribution that would preclude use in RT planning. Moreover, the differences between intensity histograms in the original and registered SPECT image sets were the largest for diffeomorphic demons and level set methods. In conclusion, the use of intensity-based validation measures alone is not sufficient for SPECT/CT registration for RTTP. It was also found that the proper evaluation of image registration requires the use of several accuracy metrics.

A new strategy for online adaptive prostate radiotherapy based on cone-beam CT

International Nuclear Information System (INIS)

Boggula, Ramesh; Lorenz, Friedlieb; Lohr, Frank; Wolff, Dirk; Boda-Heggemann, Judit; Hesser, Juergen; Wenz, Frederik; Wertz, Hansjoerg

2009-01-01

Interfractional organ motion and patient positioning errors during prostate radiotherapy can have deleterious clinical consequences. It has become clinical practice to re-position the patient with image-guided translational position correction before each treatment to compensate for those errors. However, tilt errors can only be corrected with table corrections in six degrees of freedom or ''full'' adaptive treatment planning strategies. Organ shape deformations can only be corrected by ''full'' plan adaptation. This study evaluates the potential of instant treatment plan adaptation (fast isodose line adaptation with real-time dose manipulating tools) based on cone-beam CT (CBCT) to further improve treatment quality. Using in-house software, CBCTs were modified to approximate a correct density calibration. To evaluate the dosimetric accuracy, dose distributions based on CBCTs were compared with dose distributions calculated on conventional planning CTs (PCT) for four datasets (one inhomogeneous phantom, three patient datasets). To determine the potential dosimetric benefit of a ''full'' plan adaptation over translational position correction, dose distributions were re-optimized using graphical ''online'' dose modification tools for three additional patients' CT-datasets with a substantially distended rectum while the original plans have been created with an empty rectum (single treatment fraction estimates). Absolute dose deviations of up to 51% in comparison to the PCT were observed when uncorrected CBCTs were used for replanning. After density calibration of the CBCTs, 97% of the dose deviations were ≤3% (gamma index: 3%/3 mm). Translational position correction restored the PTV dose (D 95 ) to 73% of the corresponding dose of the reference plan. After plan adaptation, larger improvements of dose restoration to 95% were observed. Additionally, the rectal dose (D 30 ) was further decreased by 42 percentage points (mean of three patient datasets). An accurate dose

Prospective economical evaluation of the image guided radiotherapy (I.G.R.T.) applied to prostate cancers. Preliminary results of the study 'program to support innovative and costly techniques (S.t.i.c.)-I.G.R.T

International Nuclear Information System (INIS)

Pommier, P.; Morelle, M.; Remonnay, R.; Crevoisier, R. de

2009-01-01

The preliminary results of the economical analysis of CT-guided radiotherapy use shows on one hand, a significant increase in the length of irradiation sessions related to the image guidance, but also on the other hand a substantial inter centrum variability yet to explore. (N.C.)

WE-FG-BRA-09: Using Graphene Oxide Nano Flakes During Image Guided Radiotherapy to Minimize the Potential of Cancer Recurrence Or Metastasis

Energy Technology Data Exchange (ETDEWEB)

Toomeh, D; Sajo, E; Hao, Y; Gadoue, S [University Massachusetts Lowell, Lowell, MA (United States); Ngwa, W [University Massachusetts Lowell, Lowell, MA (United States); Harvard Medical School, Boston, MA (United States)

2016-06-15

Purpose: An increasing number of studies show that cancer stem cells (CSCs) become more invasive (metastatic) and may escape into the blood stream and lymph nodes during radiotherapy (RT), before they have received a lethal dose during RT. Other Studies have shown that Graphene oxide (GO) can selectively inhibit the proliferative expansion of CSCs across multiplicative tumor types. In this study we investigate the feasibility of using GO during radiotherapy (RT) to minimize the escape of CSCs towards preventing cancer metastasis or recurrence. Methods: We hypothesize that sufficient amount of GO nano-flakes (GONFs) released from new design radiotherapy biomaterials (fiducials or spacers) loaded with the GONFs can reach all tumor cells within typical times of 14 or 21days before the beginning of image-guided radiotherapy (IGRT) following implantation. To test this hypothesis, the space-time diffusion of the GONFs was investigated. Knudsen’s and Cunningham’s numbers were calculated to get the Stokes’ velocities and mobility values, according to these values, diffusion coefficients were calculated. In a previous study it was shown that GONFs concentration of 50 µg/ml were effective. In the diffusion study, 100 µg/ml was chosen as an initial concentration because it has been shown to be relatively non-toxic. Results: The 50 µg/ml concentration in a 2 cm diameter volume of lung tumor could be only achieved using 2 nm and 6 nm GONFs with respective diffusion times of 14 and 21 days. As expected, increased nanoflake size requires longer times to achieve the target 50 µg/ml concentration. Conclusion: The preliminary results indicate the potential of using GONFs delivered via new design radiotherapy biomaterials (e.g. fiducials) to inhibit the proliferative expansion of CSCs. The study avails ongoing in-vivo studies on using GONFs to enhance treatment outcomes for cancer patients.

Specific recommendations for accurate and direct use of PET-CT in PET guided radiotherapy for head and neck sites

Energy Technology Data Exchange (ETDEWEB)

Thomas, C. M., E-mail: christopher.thomas@gstt.nhs.uk; Convery, D. J.; Greener, A. G. [Guy' s and St. Thomas’ NHS Foundation Trust, Medical Physics Department, St. Thomas’ Hospital, London SE1 7EH (United Kingdom); Pike, L. C.; Baker, S.; Woods, E. [Division of Imaging Sciences and Biomedical Engineering, King' s College London, King' s Health Partners, St. Thomas’ Hospital, London SE1 7EH (United Kingdom); Hartill, C. E. [Guy' s and St. Thomas’ NHS Foundation Trust, Radiotherapy, Clinical Outpatients Clinic, St. Thomas’ Hospital, London SE1 7EH (United Kingdom)

2014-04-15

Purpose: To provide specific experience-based guidance and recommendations for centers wishing to develop, validate, and implement an accurate and efficient process for directly using positron emission tomography-computed tomography (PET-CT) for the radiotherapy planning of head and neck cancer patients. Methods: A PET-CT system was modified with hard-top couch, external lasers and radiotherapy immobilization and indexing devices and was subject to a commissioning and quality assurance program. PET-CT imaging protocols were developed specifically for radiotherapy planning and the image quality and pathway tested using phantoms and five patients recruited into an in-house study. Security and accuracy of data transfer was tested throughout the whole data pathway. The patient pathway was fully established and tested ready for implementation in a PET-guided dose-escalation trial for head and neck cancer patients. Results: Couch deflection was greater than for departmental CT simulator machines. An area of high attenuation in the couch generated image artifacts and adjustments were made accordingly. Using newly developed protocols CT image quality was suitable to maintain delineation and treatment accuracy. Upon transfer of data to the treatment planning system a half pixel offset between PET and CT was observed and corrected. By taking this into account, PET to CT alignment accuracy was maintained below 1 mm in all systems in the data pathway. Transfer of structures delineated in the PET fusion software to the radiotherapy treatment planning system was validated. Conclusions: A method to perform direct PET-guided radiotherapy planning was successfully validated and specific recommendations were developed to assist other centers. Of major concern is ensuring that the quality of PET and CT data is appropriate for radiotherapy treatment planning and on-treatment verification. Couch movements can be compromised, bore-size can be a limitation for certain immobilization

Specific recommendations for accurate and direct use of PET-CT in PET guided radiotherapy for head and neck sites

International Nuclear Information System (INIS)

Thomas, C. M.; Convery, D. J.; Greener, A. G.; Pike, L. C.; Baker, S.; Woods, E.; Hartill, C. E.

2014-01-01

Purpose: To provide specific experience-based guidance and recommendations for centers wishing to develop, validate, and implement an accurate and efficient process for directly using positron emission tomography-computed tomography (PET-CT) for the radiotherapy planning of head and neck cancer patients. Methods: A PET-CT system was modified with hard-top couch, external lasers and radiotherapy immobilization and indexing devices and was subject to a commissioning and quality assurance program. PET-CT imaging protocols were developed specifically for radiotherapy planning and the image quality and pathway tested using phantoms and five patients recruited into an in-house study. Security and accuracy of data transfer was tested throughout the whole data pathway. The patient pathway was fully established and tested ready for implementation in a PET-guided dose-escalation trial for head and neck cancer patients. Results: Couch deflection was greater than for departmental CT simulator machines. An area of high attenuation in the couch generated image artifacts and adjustments were made accordingly. Using newly developed protocols CT image quality was suitable to maintain delineation and treatment accuracy. Upon transfer of data to the treatment planning system a half pixel offset between PET and CT was observed and corrected. By taking this into account, PET to CT alignment accuracy was maintained below 1 mm in all systems in the data pathway. Transfer of structures delineated in the PET fusion software to the radiotherapy treatment planning system was validated. Conclusions: A method to perform direct PET-guided radiotherapy planning was successfully validated and specific recommendations were developed to assist other centers. Of major concern is ensuring that the quality of PET and CT data is appropriate for radiotherapy treatment planning and on-treatment verification. Couch movements can be compromised, bore-size can be a limitation for certain immobilization

Evaluation of motion measurement using cine MRI for image guided stereotactic body radiotherapy on a new phantom platform

Science.gov (United States)

Cai, Jing; Wang, Ziheng; Yin, Fang-Fang

2011-01-01

The objective of this study is to investigate accuracy of motion tracking of cine magnetic resonance imaging (MRI) for image-guided stereotactic body radiotherapy. A phantom platform was developed in this work to fulfill the goal. The motion phantom consisted of a platform, a solid thread, a motor and a control system that can simulate motion in various modes. To validate its reproducibility, the phantom platform was setup three times and imaged with fluoroscopy using an electronic portal imaging device (EPID) for the same motion profile. After the validation test, the phantom platform was evaluated using cine MRI at 2.5 frames/second on a 1.5T GE scanner using five different artificial profiles and five patient profiles. The above profiles were again measured with EPID fluoroscopy and used as references. Discrepancies between measured profiles from cine MRI and EPID were quantified using root-mean-square (RMS) and standard deviation (SD). Pearson’s product moment correlational analysis was used to test correlation. The standard deviation for the reproducibility test was 0.28 mm. The discrepancies (RMS) between all profiles measured by cine MRI and EPID fluoroscopy ranged from 0.30 to 0.49 mm for artificial profiles and ranged from 0.75 to 0.91 mm for five patient profiles. The cine MRI sequence could precisely track phantom motion and the proposed motion phantom was feasible to evaluate cine MRI accuracy. PMID:29296304

Magnitude of speed of sound aberration corrections for ultrasound image guided radiotherapy for prostate and other anatomical sites

International Nuclear Information System (INIS)

Fontanarosa, Davide; Meer, Skadi van der; Bloemen-van Gurp, Esther; Stroian, Gabriela; Verhaegen, Frank

2012-01-01

Purpose: The purpose of this work is to assess the magnitude of speed of sound (SOS) aberrations in three-dimensional ultrasound (US) imaging systems in image guided radiotherapy. The discrepancy between the fixed SOS value of 1540 m/s assumed by US systems in human soft tissues and its actual nonhomogeneous distribution in patients produces small but systematic errors of up to a few millimeters in the positions of scanned structures. Methods: A correction, provided by a previously published density-based algorithm, was applied to a set of five prostate, five liver, and five breast cancer patients. The shifts of the centroids of target structures and the change in shape were evaluated. Results: After the correction the prostate cases showed shifts up to 3.6 mm toward the US probe, which may explain largely the reported positioning discrepancies in the literature on US systems versus other imaging modalities. Liver cases showed the largest changes in volume of the organ, up to almost 9%, and shifts of the centroids up to more than 6 mm either away or toward the US probe. Breast images showed systematic small shifts of the centroids toward the US probe with a maximum magnitude of 1.3 mm. Conclusions: The applied correction in prostate and liver cancer patients shows positioning errors of several mm due to SOS aberration; the errors are smaller in breast cancer cases, but possibly becoming more important when breast tissue thickness increases.

Impact of intensity-modulated and image-guided radiotherapy on elderly patients undergoing chemoradiation for locally advanced head and neck cancer

International Nuclear Information System (INIS)

Nguyen, N.P.; Chi, A.; Vock, J.

2012-01-01

Purpose: In this work, the treatment tolerance of elderly patients (≥ 70 years) undergoing intensity-modulated radiotherapy (IMRT) and image-guided radiotherapy (IGRT) and chemotherapy for locally advanced head and neck cancer was assessed. Patients and methods: A retrospective review of 112 patients undergoing concurrent chemoradiation for locally advanced head and neck cancer was performed. Treatment toxicity, protocol violations, long-term complications, and survival were compared between 85 younger patients (< 70 years) and 27 older patients (≥ 70 years). Results: Grade 3-4 treatment toxicity was observed in 88.2% and 88.8% for younger and older patients, respectively. Mean weight loss and treatment break were 5.9 and 3.9 kg (p = 0.03) and 7.3 and 7.8 days (p = 0.8) for younger and older patients, respectively. Seven patients (8.2%) did not complete treatment in the younger group compared to 1 patient (3.7%) in the older group (p = 0.6). No significant differences in protocol violations and survival were found between the two groups. Conclusion: Compared to younger patients, elderly patients with locally advanced head and neck cancer tolerated chemoradiation with IMRT and IGRT well, and should not be denied curative treatment based solely on age. (orig.)

Artificial neural network based gynaecological image-guided adaptive brachytherapy treatment planning correction of intra-fractional organs at risk dose variation.

Science.gov (United States)

Jaberi, Ramin; Siavashpour, Zahra; Aghamiri, Mahmoud Reza; Kirisits, Christian; Ghaderi, Reza

2017-12-01

Intra-fractional organs at risk (OARs) deformations can lead to dose variation during image-guided adaptive brachytherapy (IGABT). The aim of this study was to modify the final accepted brachytherapy treatment plan to dosimetrically compensate for these intra-fractional organs-applicators position variations and, at the same time, fulfilling the dosimetric criteria. Thirty patients with locally advanced cervical cancer, after external beam radiotherapy (EBRT) of 45-50 Gy over five to six weeks with concomitant weekly chemotherapy, and qualified for intracavitary high-dose-rate (HDR) brachytherapy with tandem-ovoid applicators were selected for this study. Second computed tomography scan was done for each patient after finishing brachytherapy treatment with applicators in situ. Artificial neural networks (ANNs) based models were used to predict intra-fractional OARs dose-volume histogram parameters variations and propose a new final plan. A model was developed to estimate the intra-fractional organs dose variations during gynaecological intracavitary brachytherapy. Also, ANNs were used to modify the final brachytherapy treatment plan to compensate dosimetrically for changes in 'organs-applicators', while maintaining target dose at the original level. There are semi-automatic and fast responding models that can be used in the routine clinical workflow to reduce individually IGABT uncertainties. These models can be more validated by more patients' plans to be able to serve as a clinical tool.

Artificial neural network based gynaecological image-guided adaptive brachytherapy treatment planning correction of intra-fractional organs at risk dose variation

Directory of Open Access Journals (Sweden)

Ramin Jaberi

2017-12-01

Full Text Available Purpose : Intra-fractional organs at risk (OARs deformations can lead to dose variation during image-guided adaptive brachytherapy (IGABT. The aim of this study was to modify the final accepted brachytherapy treatment plan to dosimetrically compensate for these intra-fractional organs-applicators position variations and, at the same time, fulfilling the dosimetric criteria. Material and methods : Thirty patients with locally advanced cervical cancer, after external beam radiotherapy (EBRT of 45-50 Gy over five to six weeks with concomitant weekly chemotherapy, and qualified for intracavitary high-dose-rate (HDR brachytherapy with tandem-ovoid applicators were selected for this study. Second computed tomography scan was done for each patient after finishing brachytherapy treatment with applicators in situ. Artificial neural networks (ANNs based models were used to predict intra-fractional OARs dose-volume histogram parameters variations and propose a new final plan. Results : A model was developed to estimate the intra-fractional organs dose variations during gynaecological intracavitary brachytherapy. Also, ANNs were used to modify the final brachytherapy treatment plan to compensate dosimetrically for changes in ‘organs-applicators’, while maintaining target dose at the original level. Conclusions : There are semi-automatic and fast responding models that can be used in the routine clinical workflow to reduce individually IGABT uncertainties. These models can be more validated by more patients’ plans to be able to serve as a clinical tool.

Toxicity after post-prostatectomy image-guided intensity-modulated radiotherapy using Australian guidelines.

Science.gov (United States)

Chin, Stephen; Aherne, Noel J; Last, Andrew; Assareh, Hassan; Shakespeare, Thomas P

2017-12-01

We evaluated single institution toxicity outcomes after post-prostatectomy radiotherapy (PPRT) via image-guided intensity-modulated radiation therapy (IG-IMRT) with implanted fiducial markers following national eviQ guidelines, for which late toxicity outcomes have not been published. Prospectively collected toxicity data were retrospectively reviewed for 293 men who underwent 64-66 Gy IG-IMRT to the prostate bed between 2007 and 2015. Median follow-up after PPRT was 39 months. Baseline grade ≥2 genitourinary (GU), gastrointestinal (GI) and sexual toxicities were 20.5%, 2.7% and 43.7%, respectively, reflecting ongoing toxicity after radical prostatectomy. Incidence of new (compared to baseline) acute grade ≥2 GU and GI toxicity was 5.8% and 10.6%, respectively. New late grade ≥2 GU, GI and sexual toxicity occurred in 19.1%, 4.7% and 20.2%, respectively. However, many patients also experienced improvements in toxicities. For this reason, prevalence of grade ≥2 GU, GI and sexual toxicities 4 years after PPRT was similar to or lower than baseline (21.7%, 2.6% and 17.4%, respectively). There were no grade ≥4 toxicities. Post-prostatectomy IG-IMRT using Australian contouring guidelines appears to have tolerable acute and late toxicity. The 4-year prevalence of grade ≥2 GU and GI toxicity was virtually unchanged compared to baseline, and sexual toxicity improved over baseline. This should reassure radiation oncologists following these guidelines. Late toxicity rates of surgery and PPRT are higher than following definitive IG-IMRT, and this should be taken into account if patients are considering surgery and likely to require PPRT. © 2017 The Royal Australian and New Zealand College of Radiologists.

Effect of rectal enema on intrafraction prostate movement during image-guided radiotherapy.

Science.gov (United States)

Choi, Youngmin; Kwak, Dong-Won; Lee, Hyung-Sik; Hur, Won-Joo; Cho, Won-Yeol; Sung, Gyung Tak; Kim, Tae-Hyo; Kim, Soo-Dong; Yun, Seong-Guk

2015-04-01

Rectal volume and movement are major factors that influence prostate location. The aim of this study was to assess the effect of a rectal enema on intrafraction prostate motion. The data from 12 patients with localised prostate cancer were analysed. Each patient underwent image-guided radiotherapy (RT), receiving a total dose of 70 Gy in 28 fractions. Rectal enemas were administered to all of the patients before each RT fraction. The location of the prostate was determined by implanting three fiducial markers under the guidance of transrectal ultrasound. Each patient underwent preparation for IGRT twice before an RT fraction and in the middle of the fraction. The intrafraction displacement of the prostate was calculated by comparing fiducial marker locations before and in the middle of an RT fraction. The rectal enemas were well tolerated by patients. The mean intrafraction prostate movement in 336 RT fractions was 1.11 ± 0.77 mm (range 0.08-7.20 mm). Intrafraction motions of 1, 2 and 3 mm were observed in 56.0%, 89.0% and 97.6% of all RT fractions, respectively. The intrafraction movements on supero-inferior and anteroposterior axes were larger than on the right-to-left axes (P movement, calculated using the van Herk formula (2.5Σ + 0.7σ), was 1.50 mm. A daily rectal enema before each RT fraction was tolerable and yielded little intrafraction prostate displacement. We think the use of rectal enemas is a feasible method to reduce prostate movement during RT. © 2014 The Royal Australian and New Zealand College of Radiologists.

Effect of rectal enema on intrafraction prostate movement during image-guided radiotherapy

International Nuclear Information System (INIS)

Choi, Youngmin; Kwak, Dong-Won; Lee, Hyung-Sik; Hur, Won-Jooh; Cho, Won-Yeol; Sung, Gyung Tak; Kim, Tae-Hyo; Kim, Soo-Dong; Yun, Seong-Guk

2015-01-01

Rectal volume and movement are major factors that influence prostate location. The aim of this study was to assess the effect of a rectal enema on intrafraction prostate motion. The data from 12 patients with localised prostate cancer were analysed. Each patient underwent image-guided radiotherapy (RT), receiving a total dose of 70 Gy in 28 fractions. Rectal enemas were administered to all of the patients before each RT fraction. The location of the prostate was determined by implanting three fiducial markers under the guidance of transrectal ultrasound. Each patient underwent preparation for IGRT twice before an RT fraction and in the middle of the fraction. The intrafraction displacement of the prostate was calculated by comparing fiducial marker locations before and in the middle of an RT fraction. The rectal enemas were well tolerated by patients. The mean intrafraction prostate movement in 336 RT fractions was 1.11 ± 0.77 mm (range 0.08–7.20 mm). Intrafraction motions of 1, 2 and 3 mm were observed in 56.0%, 89.0% and 97.6% of all RT fractions, respectively. The intrafraction movements on supero-inferior and anteroposterior axes were larger than on the right-to-left axes (P < 0.05). The CTV-to-PTV margin necessary to allow for movement, calculated using the van Herk formula (2.5Σ + 0.7σ), was 1.50 mm. A daily rectal enema before each RT fraction was tolerable and yielded little intrafraction prostate displacement. We think the use of rectal enemas is a feasible method to reduce prostate movement during RT.

SU-C-BRA-01: Interactive Auto-Segmentation for Bowel in Online Adaptive MRI-Guided Radiation Therapy by Using a Multi-Region Labeling Algorithm

International Nuclear Information System (INIS)

Lu, Y; Chen, I; Kashani, R; Wan, H; Maughan, N; Muccigrosso, D; Parikh, P

2016-01-01

Purpose: In MRI-guided online adaptive radiation therapy, re-contouring of bowel is time-consuming and can impact the overall time of patients on table. The study aims to auto-segment bowel on volumetric MR images by using an interactive multi-region labeling algorithm. Methods: 5 Patients with locally advanced pancreatic cancer underwent fractionated radiotherapy (18–25 fractions each, total 118 fractions) on an MRI-guided radiation therapy system with a 0.35 Tesla magnet and three Co-60 sources. At each fraction, a volumetric MR image of the patient was acquired when the patient was in the treatment position. An interactive two-dimensional multi-region labeling technique based on graph cut solver was applied on several typical MRI images to segment the large bowel and small bowel, followed by a shape based contour interpolation for generating entire bowel contours along all image slices. The resulted contours were compared with the physician’s manual contouring by using metrics of Dice coefficient and Hausdorff distance. Results: Image data sets from the first 5 fractions of each patient were selected (total of 25 image data sets) for the segmentation test. The algorithm segmented the large and small bowel effectively and efficiently. All bowel segments were successfully identified, auto-contoured and matched with manual contours. The time cost by the algorithm for each image slice was within 30 seconds. For large bowel, the calculated Dice coefficients and Hausdorff distances (mean±std) were 0.77±0.07 and 13.13±5.01mm, respectively; for small bowel, the corresponding metrics were 0.73±0.08and 14.15±4.72mm, respectively. Conclusion: The preliminary results demonstrated the potential of the proposed algorithm in auto-segmenting large and small bowel on low field MRI images in MRI-guided adaptive radiation therapy. Further work will be focused on improving its segmentation accuracy and lessening human interaction.

SU-C-BRA-01: Interactive Auto-Segmentation for Bowel in Online Adaptive MRI-Guided Radiation Therapy by Using a Multi-Region Labeling Algorithm

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Lu, Y; Chen, I; Kashani, R; Wan, H; Maughan, N; Muccigrosso, D; Parikh, P [Washington University School of Medicine, Saint Louis, MO (United States)

2016-06-15

Purpose: In MRI-guided online adaptive radiation therapy, re-contouring of bowel is time-consuming and can impact the overall time of patients on table. The study aims to auto-segment bowel on volumetric MR images by using an interactive multi-region labeling algorithm. Methods: 5 Patients with locally advanced pancreatic cancer underwent fractionated radiotherapy (18–25 fractions each, total 118 fractions) on an MRI-guided radiation therapy system with a 0.35 Tesla magnet and three Co-60 sources. At each fraction, a volumetric MR image of the patient was acquired when the patient was in the treatment position. An interactive two-dimensional multi-region labeling technique based on graph cut solver was applied on several typical MRI images to segment the large bowel and small bowel, followed by a shape based contour interpolation for generating entire bowel contours along all image slices. The resulted contours were compared with the physician’s manual contouring by using metrics of Dice coefficient and Hausdorff distance. Results: Image data sets from the first 5 fractions of each patient were selected (total of 25 image data sets) for the segmentation test. The algorithm segmented the large and small bowel effectively and efficiently. All bowel segments were successfully identified, auto-contoured and matched with manual contours. The time cost by the algorithm for each image slice was within 30 seconds. For large bowel, the calculated Dice coefficients and Hausdorff distances (mean±std) were 0.77±0.07 and 13.13±5.01mm, respectively; for small bowel, the corresponding metrics were 0.73±0.08and 14.15±4.72mm, respectively. Conclusion: The preliminary results demonstrated the potential of the proposed algorithm in auto-segmenting large and small bowel on low field MRI images in MRI-guided adaptive radiation therapy. Further work will be focused on improving its segmentation accuracy and lessening human interaction.

Definitive Upfront Stereotactic Ablative Radiotherapy Combined with Image-Guided, Intensity Modulated Radiotherapy (IG-IMRT or IG-IMRT Alone for Locally Advanced Non-Small Cell Lung Cancer.

Directory of Open Access Journals (Sweden)

Alexander Chi

Full Text Available Image-guided (IG intensity-modulated radiotherapy (IMRT enables maximal tumor margin reduction for the sparing of organs at risk (OARs when used to treat locally advanced non-small cell lung cancer (NSCLC with definitive chemo-radiation. It also allows for the incorporation of stereotactic ablative radiotherapy (SABR into the treatment regimen. Here, we describe our initial experience in combining definitive upfront SABR to the primary lesion with chemo-radiation delivered with conventionally fractionated IG-IMRT to the remaining regional disease; along with clinical outcome following chemo-radiation with conventionally fractionated IG-IMRT alone in the treatment of locally advanced NSCLC.The clinical outcome of 29 patients with locally advanced NSCLC who underwent conventionally fractionated IG-IMRT, or definitive upfront SABR followed by IG-IMRT combined with chemotherapy (induction, concurrent, or both was retrospectively reviewed.After a median follow up of 23.7 months, the median overall survival (OS and progression-free survival (PFS were 19.8 and 11.3 months, respectively. The 2 year local, regional, and distant control was 60%, 62%, and 38%, respectively. No local failure was observed in 3 patients following SABR + IG-IMRT while 6/26 patients failed locally following IG-IMRT alone. SABR + IG-IMRT was well tolerated. No ≥ grade 3 radiation-related toxicity was observed.Definitive upfront SABR followed by IG-IMRT in selected patients with locally advanced NSCLC warrants further investigation in future clinical trials, while chemo-radiation with IG-IMRT alone was well tolerated.

Feasibility of breathing-adapted PET/CT imaging for radiation therapy of Hodgkin lymphoma

DEFF Research Database (Denmark)

Aznar, M C; Andersen, Flemming; Berthelsen, A K

2011-01-01

Aim: Respiration can induce artifacts in positron emission tomography (PET)/computed tomography (CT) images leading to uncertainties in tumour volume, location and uptake quantification. Respiratory gating for PET images is now established but is not directly translatable to a radiotherapy setup....... in PET/CT images. These results suggest that advanced therapies (such as SUV-based dose painting) will likely require breathing-adapted PET images and that the relevant SUV thresholds are yet to be investigated....

Preoperative intensity-modulated and image-guided radiotherapy with a simultaneous integrated boost in locally advanced rectal cancer: Report on late toxicity and outcome

International Nuclear Information System (INIS)

Engels, Benedikt; Platteaux, Nele; Van den Begin, Robbe; Gevaert, Thierry; Sermeus, Alexandra; Storme, Guy; Verellen, Dirk; De Ridder, Mark

2014-01-01

Background and purpose: The addition of chemotherapy to preoperative radiotherapy has been established as the standard of care for patients with cT3-4 rectal cancer. As an alternative strategy, we explored intensity-modulated and image-guided radiotherapy (IMRT–IGRT) with a simultaneous integrated boost (SIB) in a prospective phase II study. Here, we report outcome and late toxicity after a median follow-up of 54 months. Methods and materials: A total of 108 patients were treated preoperatively with IMRT–IGRT, delivering a dose of 46 Gy in fractions of 2 Gy. Patients (n = 57) displaying an anticipated circumferential resection margin (CRM) of less than 2 mm based on magnetic resonance imaging received a SIB to the tumor up to a total dose of 55.2 Gy. Results: The absolute incidence of grade ⩾3 late gastrointestinal and urinary toxicity was 9% and 4%, respectively, with a 13% rate of any grade ⩾3 late toxicity. The actuarial 5-year local control (LC), progression-free survival (PFS) and overall survival (OS) were 97%, 57%, and 68%. On multivariate analysis, R1 resection and pN2 disease were associated with significantly impaired OS. Conclusions: The use of preoperative IMRT–IGRT with a SIB resulted in a high 5-year LC rate and non-negligible late toxicity

Clinical Outcomes of Patients Receiving Integrated PET/CT-Guided Radiotherapy for Head and Neck Carcinoma

International Nuclear Information System (INIS)

Vernon, Matthew R.; Maheshwari, Mohit; Schultz, Christopher J.; Michel, Michelle A.; Wong, Stuart J.; Campbell, Bruce H.; Massey, Becky L.; Wilson, J. Frank; Wang Dian

2008-01-01

Purpose: We previously reported the advantages of 18 F-fluorodeoxyglucose-positron emission tomography (PET) fused with CT for radiotherapy planning over CT alone in head and neck carcinoma (HNC). The purpose of this study was to evaluate clinical outcomes and the predictive value of PET for patients receiving PET/CT-guided definitive radiotherapy with or without chemotherapy. Methods and Materials: From December 2002 to August 2006, 42 patients received PET/CT imaging as part of staging and radiotherapy planning. Clinical outcomes including locoregional recurrence, distant metastasis, death, and treatment-related toxicities were collected retrospectively and analyzed for disease-free and overall survival and cumulative incidence of recurrence. Results: Median follow-up from initiation of treatment was 32 months. Overall survival and disease-free survival were 82.8% and 71.0%, respectively, at 2 years, and 74.1% and 66.9% at 3 years. Of the 42 patients, seven recurrences were identified (three LR, one DM, three both LR and DM). Mean time to recurrence was 9.4 months. Cumulative risk of recurrence was 18.7%. The maximum standard uptake volume (SUV) of primary tumor, adenopathy, or both on PET did not correlate with recurrence, with mean values of 12.0 for treatment failures vs. 11.7 for all patients. Toxicities identified in those patients receiving intensity modulated radiation therapy were also evaluated. Conclusions: A high level of disease control combined with favorable toxicity profiles was achieved in a cohort of HNC patients receiving PET/CT fusion guided radiotherapy plus/minus chemotherapy. Maximum SUV of primary tumor and/or adenopathy was not predictive of risk of disease recurrence

MR images of oral cancer treated with preoperative radiotherapy

International Nuclear Information System (INIS)

Onizawa, Kojiro; Niitsu Mamoru; Yusa, Hiroshi; Yanagawa, Toru; Yoshida, Hiroshi

2003-01-01

This study was carried out to evaluate the relationship between the effect of preoperative radiotherapy for oral cancer and the changes of signal intensity with MR images. T2-weighted images were compared before and after radiotherapy in 18 patients with primary oral cancer, and the effect on the lesions was histologically evaluated in surgically resected specimens obtained four weeks after the therapy. The MR images showed significantly decreased signal intensity of the lesions. The decrease of signal intensity was remarkable starting at two weeks after completion of the radiotherapy, compared with the decrease at less than two weeks after the therapy. The change of signal intensity was more obvious in tongue cancer than in other oral cancers. There was no significant difference in the change of the signal intensity between cancers with histologically poor response to the therapy and those with good response. These results suggested that signal intensity of oral cancer on T2-weighted images showed a significant decrease after preoperative radiotherapy, and that the intensity could be affected by duration after radiotherapy and primary sites. (author)

A modified VMAT adaptive radiotherapy for nasopharyngeal cancer patients based on CT-CT image fusion

International Nuclear Information System (INIS)

Jin, Xiance; Han, Ce; Zhou, Yongqiang; Yi, Jinling; Yan, Huawei; Xie, Congying

2013-01-01

To investigate the feasibility and benefits of a modified adaptive radiotherapy (ART) by replanning in the initial CT (iCT) with new contours from a repeat CT (rCT) based on CT-CT image fusion for nasopharyngeal cancer (NPC) patients underwent volumetric modulated arc radiotherapy (VMAT). Nine NPC patients underwent VMAT treatment with a rCT at 23rd fraction were enrolled in this study. Dosimetric differences for replanning VMAT plans in the iCT and in the rCT were compared. Volumetric and dosimetric changes of gross tumor volume (GTV) and organs at risk (OARs) of this modified ART were also investigated. No dosimetric differences between replanning in the iCT and in the rCT were observed. The average volume of GTV decreased from 78.83 ± 38.42 cm 3 in the iCT to 71.44 ± 37.46 cm 3 in the rCT, but with no significant difference (p = 0.42).The average volume of the left and right parotid decreased from 19.91 ± 4.89 cm 3 and 21.58 ± 6.16 cm 3 in the iCT to 11.80 ± 2.79 cm 3 and 13.29 ± 4.17 cm 3 in the rCT (both p < 0.01), respectively. The volume of other OARs did not shrink very much. No significant differences on PTV GTV and PTV CTV coverage were observed for replanning with this modified ART. Compared to the initial plans, the average mean dose of the left and right parotid after re-optimization were decreased by 62.5 cGy (p = 0.05) and 67.3 cGy (p = 0.02), respectively, and the V5 (the volume receiving 5 Gy) of the left and right parotids were decreased by 7.8% (p = 0.01) and 11.2% (p = 0.001), respectively. There was no significant difference on the dose delivered to other OARs. Patients with NPC undergoing VMAT have significant anatomic and dosimetric changes to parotids. Repeat CT as an anatomic changes reference and re-optimization in the iCT based on CT-CT image fusion was accurate enough to identify the volume changes and to ensure safe dose to parotids

A retrospective comparison of outcome and toxicity of preoperative image-guided intensity-modulated radiotherapy versus conventional pelvic radiotherapy for locally advanced rectal carcinoma

International Nuclear Information System (INIS)

Huang, Chun-Ming; Huang, Ming-Yii; Tsai, Hsiang-Lin; Huang, Ching-Wen; Ma, Cheng-Jen; Lin, Chih-Hung; Huang, Chih-Jen; Wang, Jaw-Yuan

2017-01-01

The aim of the study was to compare clinical outcomes and toxicity between 3D conformal radiotherapy (3DCRT) and image-guided intensity-modulated radiotherapy (IG-IMRT) administered through helical tomotherapy in locally advanced rectal cancer (LARC) patients receiving preoperative chemoradiotherapy. We reviewed 144 patients with Stage II–III rectal cancer receiving preoperative fluoropyrimidine-based chemoradiotherapy followed by radical resection. Tumor responses following chemoradiotherapy were evaluated using the Dworak tumor regression grade (TRG). Of the 144 patients, 45 received IG-IMRT and 99 received 3DCRT. A significant reduction in Grade 3 or 4 acute gastrointestinal toxicity (IG-IMRT, 6.7%; 3DCRT, 15.1%; P = 0.039) was observed by IG-IMRT. The pathologic complete response (pCR) rate did not differ between the IG-IMRT and the 3DCRT group (17.8% vs 15.1%, P = 0.52). Patients in the IG-IMRT group had the trend of favorable tumor regressions (TRG 3 or 4) compared with those in the 3DCRT group (66.7% vs 43.5%, P = 0.071). The median follow-up was 53 months (range, 18–95 months) in the 3DCRT group and 43 months (range, 17–69 months) in the IG-IMRT group. Four-year overall, disease-free, and local failure–free survival rates of the IG-IMRT and 3DCRT groups were 81.6% and 67.9% (P = 0.12), 53.8% and 51.8% (P = 0.51), and 88% and 75.1% (P = 0.031), respectively. LARC patients treated with preoperative IG-IMRT achieved lower acute gastrointestinal adverse effects and a higher local control rate than those treated with 3DCRT, but there was no prominent difference in distant metastasis rate and overall survival between two treatment modalities.

Feasibility of breathing-adapted PET/CT imaging for radiation therapy of Hodgkin lymphoma

DEFF Research Database (Denmark)

Aznar, M C; Andersen, Flemming; Berthelsen, A K

2011-01-01

Aim: Respiration can induce artifacts in positron emission tomography (PET)/computed tomography (CT) images leading to uncertainties in tumour volume, location and uptake quantification. Respiratory gating for PET images is now established but is not directly translatable to a radiotherapy setup....... uptake in PET/CT images. These results suggest that advanced therapies (such as SUV-based dose painting) will likely require breathing-adapted PET images and that the relevant SUV thresholds are yet to be investigated....

Guide for the self-assessment of risks brought upon patients in external radiotherapy - ASN guide nr 4, Index 0, Release of the 15/01/2009

International Nuclear Information System (INIS)

2009-01-01

This document contains a user's guide for radiotherapy centres which is to be read before completing the form of analysis of failure modes, their effects and criticality (AMDEC), this form which must be completed by each radiotherapy centre, and a report explaining the methodology which has been adopted to elaborate this guide

A digital fluoroscopic imaging system for verification during external beam radiotherapy

International Nuclear Information System (INIS)

Takai, Michikatsu

1990-01-01

A digital fluoroscopic (DF) imaging system has been constructed to obtain portal images for verification during external beam radiotherapy. The imaging device consists of a fluorescent screen viewed by a highly sensitive video camera through a mirror. The video signal is digitized and processed by an image processor which is linked on-line with a host microcomputer. The image quality of the DF system was compared with that of film for portal images of the Burger phantom and the Alderson anthropomorphic phantom using 10 MV X-rays. Contrast resolution of the DF image integrated for 8.5 sec. was superior to the film resolution, while spatial resolution was slightly inferior. The DF image of the Alderson phantom processed by the adaptive histogram equalization was better in showing anatomical landmarks than the film portal image. The DF image integrated for 1 sec. which is used for movie mode can show patient movement during treatment. (author)

Cranial radiotherapy guided by computed tomography with or without fields conformation in pediatric

International Nuclear Information System (INIS)

Fernandez, Diego; Caussa, Lucas; Murina, Patricia; Zunino, Silvia

2007-01-01

Many malignancies in children can be cured by radiotherapy, acute toxicity and the significant effect of delayed treatment are worrying for the patient, family and society. Therefore, the end of the pediatric radiotherapy is to maintain or improve the cure rate of cancer, diminishing the aftermath of treatment. The goal of this study is to measure differences in doses to the healthy tissue of the central nervous system with two radiotherapy techniques, both guided by computed tomography [es

Prospective Trial of High-Dose Reirradiation Using Daily Image Guidance With Intensity-Modulated Radiotherapy for Recurrent and Second Primary Head-and-Neck Cancer

International Nuclear Information System (INIS)

Chen, Allen M.; Farwell, D. Gregory; Luu, Quang; Cheng, Suzan; Donald, Paul J.; Purdy, James A.

2011-01-01

Purpose: To report a single-institutional experience using intensity-modulated radiotherapy with daily image-guided radiotherapy for the reirradiation of recurrent and second cancers of the head and neck. Methods and Materials: Twenty-one consecutive patients were prospectively treated with intensity-modulated radiotherapy from February 2006 to March 2009 to a median dose of 66 Gy (range, 60-70 Gy). None of these patients received concurrent chemotherapy. Daily helical megavoltage CT scans were obtained before each fraction as part of an image-guided radiotherapy registration protocol for patient alignment. Results: The 1- and 2-year estimates of in-field control were 72% and 65%, respectively. A total of 651 daily megavoltage CT scans were obtained. The mean systematic shift to account for interfraction motion was 1.38 ± 1.25 mm, 1.79 ± 1.45 mm, and 1.98 ± 1.75 mm for the medial-lateral, superior-inferior, and anterior-posterior directions, respectively. Pretreatment shifts of >3 mm occurred in 19% of setups in the medial-lateral, 27% in the superior-inferior, and 33% in the anterior-posterior directions, respectively. There were no treatment-related fatalities or hospitalizations. Complications included skin desquamation, odynophagia, otitis externa, keratitis, naso-lacrimal duct stenosis, and brachial plexopathy. Conclusions: Intensity-modulated radiotherapy with daily image guidance results in effective disease control with relatively low morbidity and should be considered for selected patients with recurrent and second primary cancers of the head and neck.

Evaluation of image guided motion management methods in lung cancer radiotherapy

International Nuclear Information System (INIS)

Zhuang, Ling; Yan, Di; Liang, Jian; Ionascu, Dan; Mangona, Victor; Yang, Kai; Zhou, Jun

2014-01-01

Purpose: To evaluate the accuracy and reliability of three target localization methods for image guided motion management in lung cancer radiotherapy. Methods: Three online image localization methods, including (1) 2D method based on 2D cone beam (CB) projection images, (2) 3D method using 3D cone beam CT (CBCT) imaging, and (3) 4D method using 4D CBCT imaging, have been evaluated using a moving phantom controlled by (a) 1D theoretical breathing motion curves and (b) 3D target motion patterns obtained from daily treatment of 3 lung cancer patients. While all methods are able to provide target mean position (MP), the 2D and 4D methods can also provide target motion standard deviation (SD) and excursion (EX). For each method, the detected MP/SD/EX values are compared to the analytically calculated actual values to calculate the errors. The MP errors are compared among three methods and the SD/EX errors are compared between the 2D and 4D methods. In the theoretical motion study (a), the dependency of MP/SD/EX error on EX is investigated with EX varying from 2.0 cm to 3.0 cm with an increment step of 0.2 cm. In the patient motion study (b), the dependency of MP error on target sizes (2.0 cm and 3.0 cm), motion patterns (four motions per patient) and EX variations is investigated using multivariant linear regression analysis. Results: In the theoretical motion study (a), the MP detection errors are −0.2 ± 0.2, −1.5 ± 1.1, and −0.2 ± 0.2 mm for 2D, 3D, and 4D methods, respectively. Both the 2D and 4D methods could accurately detect motion pattern EX (error < 1.2 mm) and SD (error < 1.0 mm). In the patient motion study (b), MP detection error vector (mm) with the 2D method (0.7 ± 0.4) is found to be significantly less than with the 3D method (1.7 ± 0.8,p < 0.001) and the 4D method (1.4 ± 1.0, p < 0.001) using paired t-test. However, no significant difference is found between the 4D method and the 3D method. Based on multivariant linear regression analysis, the

Evaluation of image guided motion management methods in lung cancer radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Zhuang, Ling [Department of Radiation Oncology, Wayne State University School of Medicine, 4100 John R, Detroit, Michigan 48201 (United States); Yan, Di; Liang, Jian; Ionascu, Dan; Mangona, Victor; Yang, Kai; Zhou, Jun, E-mail: jun.zhou@beaumont.edu [Department of Radiation Oncology, William Beaumont Hospital, 3601 West Thirteen Mile Road, Royal Oak, Michigan 48073 (United States)

2014-03-15

Purpose: To evaluate the accuracy and reliability of three target localization methods for image guided motion management in lung cancer radiotherapy. Methods: Three online image localization methods, including (1) 2D method based on 2D cone beam (CB) projection images, (2) 3D method using 3D cone beam CT (CBCT) imaging, and (3) 4D method using 4D CBCT imaging, have been evaluated using a moving phantom controlled by (a) 1D theoretical breathing motion curves and (b) 3D target motion patterns obtained from daily treatment of 3 lung cancer patients. While all methods are able to provide target mean position (MP), the 2D and 4D methods can also provide target motion standard deviation (SD) and excursion (EX). For each method, the detected MP/SD/EX values are compared to the analytically calculated actual values to calculate the errors. The MP errors are compared among three methods and the SD/EX errors are compared between the 2D and 4D methods. In the theoretical motion study (a), the dependency of MP/SD/EX error on EX is investigated with EX varying from 2.0 cm to 3.0 cm with an increment step of 0.2 cm. In the patient motion study (b), the dependency of MP error on target sizes (2.0 cm and 3.0 cm), motion patterns (four motions per patient) and EX variations is investigated using multivariant linear regression analysis. Results: In the theoretical motion study (a), the MP detection errors are −0.2 ± 0.2, −1.5 ± 1.1, and −0.2 ± 0.2 mm for 2D, 3D, and 4D methods, respectively. Both the 2D and 4D methods could accurately detect motion pattern EX (error < 1.2 mm) and SD (error < 1.0 mm). In the patient motion study (b), MP detection error vector (mm) with the 2D method (0.7 ± 0.4) is found to be significantly less than with the 3D method (1.7 ± 0.8,p < 0.001) and the 4D method (1.4 ± 1.0, p < 0.001) using paired t-test. However, no significant difference is found between the 4D method and the 3D method. Based on multivariant linear regression analysis, the

Automatic detection of patient identification and positioning errors in radiotherapy treatment using 3D setup images

OpenAIRE

Jani, Shyam

2015-01-01

The success of modern radiotherapy treatment depends on the correct alignment of the radiation beams with the target region in the patient. In the conventional paradigm of image-guided radiation therapy, 2D or 3D setup images are taken immediately prior to treatment and are used by radiation therapy technologists to localize the patient to the same position as defined from the reference planning CT dataset. However, numerous reports in the literature have described errors during this step, wh...

A DVH-guided IMRT optimization algorithm for automatic treatment planning and adaptive radiotherapy replanning

International Nuclear Information System (INIS)

Zarepisheh, Masoud; Li, Nan; Long, Troy; Romeijn, H. Edwin; Tian, Zhen; Jia, Xun; Jiang, Steve B.

2014-01-01

Purpose: To develop a novel algorithm that incorporates prior treatment knowledge into intensity modulated radiation therapy optimization to facilitate automatic treatment planning and adaptive radiotherapy (ART) replanning. Methods: The algorithm automatically creates a treatment plan guided by the DVH curves of a reference plan that contains information on the clinician-approved dose-volume trade-offs among different targets/organs and among different portions of a DVH curve for an organ. In ART, the reference plan is the initial plan for the same patient, while for automatic treatment planning the reference plan is selected from a library of clinically approved and delivered plans of previously treated patients with similar medical conditions and geometry. The proposed algorithm employs a voxel-based optimization model and navigates the large voxel-based Pareto surface. The voxel weights are iteratively adjusted to approach a plan that is similar to the reference plan in terms of the DVHs. If the reference plan is feasible but not Pareto optimal, the algorithm generates a Pareto optimal plan with the DVHs better than the reference ones. If the reference plan is too restricting for the new geometry, the algorithm generates a Pareto plan with DVHs close to the reference ones. In both cases, the new plans have similar DVH trade-offs as the reference plans. Results: The algorithm was tested using three patient cases and found to be able to automatically adjust the voxel-weighting factors in order to generate a Pareto plan with similar DVH trade-offs as the reference plan. The algorithm has also been implemented on a GPU for high efficiency. Conclusions: A novel prior-knowledge-based optimization algorithm has been developed that automatically adjust the voxel weights and generate a clinical optimal plan at high efficiency. It is found that the new algorithm can significantly improve the plan quality and planning efficiency in ART replanning and automatic treatment

Online Adaptive Replanning Method for Prostate Radiotherapy

International Nuclear Information System (INIS)

Ahunbay, Ergun E.; Peng Cheng; Holmes, Shannon; Godley, Andrew; Lawton, Colleen; Li, X. Allen

2010-01-01

Purpose: To report the application of an adaptive replanning technique for prostate cancer radiotherapy (RT), consisting of two steps: (1) segment aperture morphing (SAM), and (2) segment weight optimization (SWO), to account for interfraction variations. Methods and Materials: The new 'SAM+SWO' scheme was retroactively applied to the daily CT images acquired for 10 prostate cancer patients on a linear accelerator and CT-on-Rails combination during the course of RT. Doses generated by the SAM+SWO scheme based on the daily CT images were compared with doses generated after patient repositioning using the current planning target volume (PTV) margin (5 mm, 3 mm toward rectum) and a reduced margin (2 mm), along with full reoptimization scans based on the daily CT images to evaluate dosimetry benefits. Results: For all cases studied, the online replanning method provided significantly better target coverage when compared with repositioning with reduced PTV (13% increase in minimum prostate dose) and improved organ sparing when compared with repositioning with regular PTV (13% decrease in the generalized equivalent uniform dose of rectum). The time required to complete the online replanning process was 6 ± 2 minutes. Conclusion: The proposed online replanning method can be used to account for interfraction variations for prostate RT with a practically acceptable time frame (5-10 min) and with significant dosimetric benefits. On the basis of this study, the developed online replanning scheme is being implemented in the clinic for prostate RT.

Using dual-energy x-ray imaging to enhance automated lung tumor tracking during real-time adaptive radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Menten, Martin J., E-mail: martin.menten@icr.ac.uk; Fast, Martin F.; Nill, Simeon; Oelfke, Uwe, E-mail: uwe.oelfke@icr.ac.uk [Joint Department of Physics at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London SM2 5NG (United Kingdom)

2015-12-15

Purpose: Real-time, markerless localization of lung tumors with kV imaging is often inhibited by ribs obscuring the tumor and poor soft-tissue contrast. This study investigates the use of dual-energy imaging, which can generate radiographs with reduced bone visibility, to enhance automated lung tumor tracking for real-time adaptive radiotherapy. Methods: kV images of an anthropomorphic breathing chest phantom were experimentally acquired and radiographs of actual lung cancer patients were Monte-Carlo-simulated at three imaging settings: low-energy (70 kVp, 1.5 mAs), high-energy (140 kVp, 2.5 mAs, 1 mm additional tin filtration), and clinical (120 kVp, 0.25 mAs). Regular dual-energy images were calculated by weighted logarithmic subtraction of high- and low-energy images and filter-free dual-energy images were generated from clinical and low-energy radiographs. The weighting factor to calculate the dual-energy images was determined by means of a novel objective score. The usefulness of dual-energy imaging for real-time tracking with an automated template matching algorithm was investigated. Results: Regular dual-energy imaging was able to increase tracking accuracy in left–right images of the anthropomorphic phantom as well as in 7 out of 24 investigated patient cases. Tracking accuracy remained comparable in three cases and decreased in five cases. Filter-free dual-energy imaging was only able to increase accuracy in 2 out of 24 cases. In four cases no change in accuracy was observed and tracking accuracy worsened in nine cases. In 9 out of 24 cases, it was not possible to define a tracking template due to poor soft-tissue contrast regardless of input images. The mean localization errors using clinical, regular dual-energy, and filter-free dual-energy radiographs were 3.85, 3.32, and 5.24 mm, respectively. Tracking success was dependent on tumor position, tumor size, imaging beam angle, and patient size. Conclusions: This study has highlighted the influence of

Using dual-energy x-ray imaging to enhance automated lung tumor tracking during real-time adaptive radiotherapy

International Nuclear Information System (INIS)

Menten, Martin J.; Fast, Martin F.; Nill, Simeon; Oelfke, Uwe

2015-01-01

Purpose: Real-time, markerless localization of lung tumors with kV imaging is often inhibited by ribs obscuring the tumor and poor soft-tissue contrast. This study investigates the use of dual-energy imaging, which can generate radiographs with reduced bone visibility, to enhance automated lung tumor tracking for real-time adaptive radiotherapy. Methods: kV images of an anthropomorphic breathing chest phantom were experimentally acquired and radiographs of actual lung cancer patients were Monte-Carlo-simulated at three imaging settings: low-energy (70 kVp, 1.5 mAs), high-energy (140 kVp, 2.5 mAs, 1 mm additional tin filtration), and clinical (120 kVp, 0.25 mAs). Regular dual-energy images were calculated by weighted logarithmic subtraction of high- and low-energy images and filter-free dual-energy images were generated from clinical and low-energy radiographs. The weighting factor to calculate the dual-energy images was determined by means of a novel objective score. The usefulness of dual-energy imaging for real-time tracking with an automated template matching algorithm was investigated. Results: Regular dual-energy imaging was able to increase tracking accuracy in left–right images of the anthropomorphic phantom as well as in 7 out of 24 investigated patient cases. Tracking accuracy remained comparable in three cases and decreased in five cases. Filter-free dual-energy imaging was only able to increase accuracy in 2 out of 24 cases. In four cases no change in accuracy was observed and tracking accuracy worsened in nine cases. In 9 out of 24 cases, it was not possible to define a tracking template due to poor soft-tissue contrast regardless of input images. The mean localization errors using clinical, regular dual-energy, and filter-free dual-energy radiographs were 3.85, 3.32, and 5.24 mm, respectively. Tracking success was dependent on tumor position, tumor size, imaging beam angle, and patient size. Conclusions: This study has highlighted the influence of

Using dual-energy x-ray imaging to enhance automated lung tumor tracking during real-time adaptive radiotherapy.

Science.gov (United States)

Menten, Martin J; Fast, Martin F; Nill, Simeon; Oelfke, Uwe

2015-12-01

Real-time, markerless localization of lung tumors with kV imaging is often inhibited by ribs obscuring the tumor and poor soft-tissue contrast. This study investigates the use of dual-energy imaging, which can generate radiographs with reduced bone visibility, to enhance automated lung tumor tracking for real-time adaptive radiotherapy. kV images of an anthropomorphic breathing chest phantom were experimentally acquired and radiographs of actual lung cancer patients were Monte-Carlo-simulated at three imaging settings: low-energy (70 kVp, 1.5 mAs), high-energy (140 kVp, 2.5 mAs, 1 mm additional tin filtration), and clinical (120 kVp, 0.25 mAs). Regular dual-energy images were calculated by weighted logarithmic subtraction of high- and low-energy images and filter-free dual-energy images were generated from clinical and low-energy radiographs. The weighting factor to calculate the dual-energy images was determined by means of a novel objective score. The usefulness of dual-energy imaging for real-time tracking with an automated template matching algorithm was investigated. Regular dual-energy imaging was able to increase tracking accuracy in left-right images of the anthropomorphic phantom as well as in 7 out of 24 investigated patient cases. Tracking accuracy remained comparable in three cases and decreased in five cases. Filter-free dual-energy imaging was only able to increase accuracy in 2 out of 24 cases. In four cases no change in accuracy was observed and tracking accuracy worsened in nine cases. In 9 out of 24 cases, it was not possible to define a tracking template due to poor soft-tissue contrast regardless of input images. The mean localization errors using clinical, regular dual-energy, and filter-free dual-energy radiographs were 3.85, 3.32, and 5.24 mm, respectively. Tracking success was dependent on tumor position, tumor size, imaging beam angle, and patient size. This study has highlighted the influence of patient anatomy on the success rate of real

Image-Guided Radiotherapy for Liver Cancer Using Respiratory-Correlated Computed Tomography and Cone-Beam Computed Tomography

International Nuclear Information System (INIS)

Guckenberger, Matthias; Sweeney, Reinhart A.; Wilbert, Juergen; Krieger, Thomas; Richter, Anne; Baier, Kurt; Mueller, Gerd; Sauer, Otto; Flentje, Michael

2008-01-01

Purpose: To evaluate a novel four-dimensional (4D) image-guided radiotherapy (IGRT) technique in stereotactic body RT for liver tumors. Methods and Materials: For 11 patients with 13 intrahepatic tumors, a respiratory-correlated 4D computed tomography (CT) scan was acquired at treatment planning. The target was defined using CT series reconstructed at end-inhalation and end-exhalation. The liver was delineated on these two CT series and served as a reference for image guidance. A cone-beam CT scan was acquired after patient positioning; the blurred diaphragm dome was interpreted as a probability density function showing the motion range of the liver. Manual contour matching of the liver structures from the planning 4D CT scan with the cone-beam CT scan was performed. Inter- and intrafractional uncertainties of target position and motion range were evaluated, and interobserver variability of the 4D-IGRT technique was tested. Results: The workflow of 4D-IGRT was successfully practiced in all patients. The absolute error in the liver position and error in relation to the bony anatomy was 8 ± 4 mm and 5 ± 2 mm (three-dimensional vector), respectively. Margins of 4-6 mm were calculated for compensation of the intrafractional drifts of the liver. The motion range of the diaphragm dome was reproducible within 5 mm for 11 of 13 lesions, and the interobserver variability of the 4D-IGRT technique was small (standard deviation, 1.5 mm). In 4 patients, the position of the intrahepatic lesion was directly verified using a mobile in-room CT scanner after application of intravenous contrast. Conclusion: The results of our study have shown that 4D image guidance using liver contour matching between respiratory-correlated CT and cone-beam CT scans increased the accuracy compared with stereotactic positioning and compared with IGRT without consideration of breathing motion

Strategies for Biologic Image-Guided Dose Escalation: A Review

International Nuclear Information System (INIS)

Sovik, Aste; Malinen, Eirik; Olsen, Dag Rune

2009-01-01

There is increasing interest in how to incorporate functional and molecular information obtained by noninvasive, three-dimensional tumor imaging into radiotherapy. The key issues are to identify radioresistant regions that can be targeted for dose escalation, and to develop radiation dose prescription and delivery strategies providing optimal treatment for the individual patient. In the present work, we review the proposed strategies for biologic image-guided dose escalation with intensity-modulated radiation therapy. Biologic imaging modalities and the derived images are discussed, as are methods for target volume delineation. Different dose escalation strategies and techniques for treatment delivery and treatment plan evaluation are also addressed. Furthermore, we consider the need for response monitoring during treatment. We conclude with a summary of the current status of biologic image-based dose escalation and of areas where further work is needed for this strategy to become incorporated into clinical practice

Surveillance after prostate cancer radiotherapy

International Nuclear Information System (INIS)

Supiot, S.; Rio, E.; Clement-Colmou, K.; Bouchot, O.; Rigaud, J.

2011-01-01

Follow-up after prostate cancer radiotherapy aims at detecting local or metastatic relapse, as well as long-term toxicity, requiring adapted treatments. Several scientific societies have published guidelines including clinical, biological and imaging recommendations. More data suggest a role for aggressive salvage therapy in case of local failure following radiotherapy. An adequate follow-up is required for the sake of patients' safety, i.e. to a posteriori validate dose constraints and radiation technique in each radiotherapy department. (authors)

Cone Beam Computed Tomography-Derived Adaptive Radiotherapy for Radical Treatment of Esophageal Cancer

International Nuclear Information System (INIS)

Hawkins, Maria A.; Brooks, Corrinne; Hansen, Vibeke N.; Aitken, Alexandra; Tait, Diana M.

2010-01-01

Purpose: To investigate the potential for reduction in normal tissue irradiation by creating a patient specific planning target volume (PTV) using cone beam computed tomography (CBCT) imaging acquired in the first week of radiotherapy for patients receiving radical radiotherapy. Methods and materials: Patients receiving radical RT for carcinoma of the esophagus were investigated. The PTV is defined as CTV(tumor, nodes) plus esophagus outlined 3 to 5 cm cranio-caudally and a 1.5-cm circumferential margin is added (clinical plan). Prefraction CBCT are acquired on Days 1 to 4, then weekly. No correction for setup error made. The images are imported into the planning system. The tumor and esophagus for the length of the PTV are contoured on each CBCT and 5 mm margin is added. A composite volume (PTV1) is created using Week 1 composite CBCT volumes. The same process is repeated using CBCT Week 2 to 6 (PTV2). A new plan is created using PTV1 (adaptive plan). The coverage of the 95% isodose of PTV1 is evaluated on PTV2. Dose-volume histograms (DVH) for lungs, heart, and cord for two plans are compared. Results: A total of 139 CBCT for 14 cases were analyzed. For the adaptive plan the coverage of the 95% prescription isodose for PTV1 = 95.6% ± 4% and the PTV2 = 96.8% ± 4.1% (t test, 0.19). Lungs V20 (15.6 Gy vs. 10.2 Gy) and heart mean dose (26.9 Gy vs. 20.7 Gy) were significantly smaller for the adaptive plan. Conclusions: A reduced planning volume can be constructed within the first week of treatment using CBCT. A single plan modification can be performed within the second week of treatment with considerable reduction in organ at risk dose.

The effect of bowel preparation regime on interfraction rectal filling variation during image guided radiotherapy for prostate cancer.

Science.gov (United States)

Hosni, Ali; Rosewall, Tara; Craig, Timothy; Kong, Vickie; Bayley, Andrew; Berlin, Alejandro; Bristow, Robert; Catton, Charles; Warde, Padraig; Chung, Peter

2017-03-09

This study aimed to investigate the tolerability and impact of milk of magnesia (MoM) on interfraction rectal filling during prostate cancer radiotherapy. Two groups were retrospectively identified, each consisting of 40 patients with prostate cancer treated with radiotherapy to prostate+/-seminal vesicles, with daily image-guidance in 78Gy/39fractions/8 weeks. The first-group followed anti-flatulence diet with MoM started 3-days prior to planning-CT and continued during radiotherapy, while the second-group followed the same anti-flatulence diet only. The rectum between upper and lower limit of the clinical target volume (CTV) was delineated on planning-CT and on weekly cone-beam-CT (CBCT). Rectal filling was assessed by measurement of anterio-posterior diameter of the rectum at the superior and mid levels of CTV, rectal volume (RV), and average cross-sectional rectal area (CSA; RV/length). Overall 720 images (80 planning-CT and 640 CBCT images) from 80 patients were analyzed. Using linear mixed models, and after adjusting for baseline values at the time of planning-CT to test the differences in rectal dimensions between both groups over the 8-week treatment period, there were no significant differences in RV (p = 0.4), CSA (p = 0.5), anterio-posterior diameter of rectum at superior (p = 0.4) or mid level of CTV (p = 0.4). In the non-MoM group; 22.5% of patients had diarrhea compared to 60% in the MoM group, while 40% discontinued use of MoM by end of radiotherapy. The addition of MoM to antiflatulence diet did not reduce the interfraction variation in rectal filling but caused diarrhea in a substantial proportion of patients who then discontinued its use.

SU-E-I-39: Molecular Image Guided Cancer Stem Cells Therapy

Energy Technology Data Exchange (ETDEWEB)

Abdollahi, H

2014-06-01

Purpose: Cancer stem cells resistance to radiation is a problematic issue that has caused a big fail in cancer treatment. Methods: As a primary work, molecular imaging can indicate the main mechanisms of radiation resistance of cancer stem cells. By developing and commissioning new probes and nanomolecules and biomarkers, radiation scientist will able to identify the essential pathways of radiation resistance of cancer stem cells. As the second solution, molecular imaging is a best way to find biological target volume and delineate cancer stem cell tissues. In the other hand, by molecular imaging techniques one can image the treatment response in tumor and also in normal tissue. In this issue, the response of cancer stem cells to radiation during therapy course can be imaged, also the main mechanisms of radiation resistance and finding the best radiation modifiers (sensitizers) can be achieved by molecular imaging modalities. In adaptive radiotherapy the molecular imaging plays a vital role to have higher tumor control probability by delivering high radiation doses to cancer stem cells in any time of treatment. The outcome of a feasible treatment is dependent to high cancer stem cells response to radiation and removing all of which, so a good imaging modality can show this issue and preventing of tumor recurrence and metastasis. Results: Our results are dependent to use of molecular imaging as a new modality in the clinic. We propose molecular imaging as a new radiobiological technique to solve radiation therapy problems due to cancer stem cells. Conclusion: Molecular imaging guided cancer stem cell diagnosis and therapy is a new approach in the field of cancer treatment. This new radiobiological imaging technique should be developed in all clinics as a feasible tool that is more biological than physical imaging.

SU-E-I-39: Molecular Image Guided Cancer Stem Cells Therapy

International Nuclear Information System (INIS)

Abdollahi, H

2014-01-01

Purpose: Cancer stem cells resistance to radiation is a problematic issue that has caused a big fail in cancer treatment. Methods: As a primary work, molecular imaging can indicate the main mechanisms of radiation resistance of cancer stem cells. By developing and commissioning new probes and nanomolecules and biomarkers, radiation scientist will able to identify the essential pathways of radiation resistance of cancer stem cells. As the second solution, molecular imaging is a best way to find biological target volume and delineate cancer stem cell tissues. In the other hand, by molecular imaging techniques one can image the treatment response in tumor and also in normal tissue. In this issue, the response of cancer stem cells to radiation during therapy course can be imaged, also the main mechanisms of radiation resistance and finding the best radiation modifiers (sensitizers) can be achieved by molecular imaging modalities. In adaptive radiotherapy the molecular imaging plays a vital role to have higher tumor control probability by delivering high radiation doses to cancer stem cells in any time of treatment. The outcome of a feasible treatment is dependent to high cancer stem cells response to radiation and removing all of which, so a good imaging modality can show this issue and preventing of tumor recurrence and metastasis. Results: Our results are dependent to use of molecular imaging as a new modality in the clinic. We propose molecular imaging as a new radiobiological technique to solve radiation therapy problems due to cancer stem cells. Conclusion: Molecular imaging guided cancer stem cell diagnosis and therapy is a new approach in the field of cancer treatment. This new radiobiological imaging technique should be developed in all clinics as a feasible tool that is more biological than physical imaging

Performance characteristics of mobile MOSFET dosimeter for kilovoltage X-rays used in image guided radiotherapy.

Science.gov (United States)

Kumar, A Sathish; Singh, I Rabi Raja; Sharma, S D; Ravindran, B Paul

2015-01-01

The main objective of this study was to investigate the characteristics of metal oxide semiconductor field effect transistor (MOSFET) dosimeter for kilovoltage (kV) X-ray beams in order to perform the in vivo dosimetry during image guidance in radiotherapy. The performance characteristics of high sensitivity MOSFET dosimeters were investigated for 80, 90, 100, 110, 120, and 125 kV X-ray beams used for imaging in radiotherapy. This study was performed using Clinac 2100 C/D medical electron linear accelerator with on-board imaging and kV cone beam computed tomography system. The characteristics studied in this work include energy dependence, angular dependence, and linearity. The X-ray beam outputs were measured as per American Association of Physicists in Medicine (AAPM) TG 61 recommendations using PTW parallel plate (PP) ionization chamber, which was calibrated in terms of air kerma (Nk) by the National Standard Laboratory. The MOSFET dosimeters were calibrated against the PP ionization chamber for all the kV X-ray beams and the calibration coefficient was found to be 0.11 cGy/mV with a standard deviation of about ±1%. The response of MOSFET was found to be energy independent for the kV X-ray energies used in this study. The response of the MOSFET dosimeter was also found independent of angle of incidence for the gantry angles in the range of 0° to 360° in-air as well as at 3 cm depth in tissue equivalent phantom.

Doses to organs and tissues from concomitant imaging in radiotherapy: a suggested framework for clinical justification.

Science.gov (United States)

Harrison, R M

2008-12-01

The increasing use of imaging for localization and verification in radiotherapy has raised issues concerning the justifiable doses to critical organs and tissues from concomitant exposures, particularly when extensive image-guided radiotherapy is indicated. Doses at positions remote from the target volume include components from high-energy leakage and scatter, as well as from concomitant imaging. In this paper, simulated prostate, breast and larynx treatments are used to compare doses from both high-energy and concomitant exposures as a function of distance from the target volume. It is suggested that the fraction, R, of the total dose at any point within the patient that is attributable to concomitant exposures may be a useful aid in their justification. R is small within the target volume and at large distances from it. However, there is a critical region immediately adjacent to the planning target volume where the dose from concomitant imaging combines with leakage and scatter to give values of R that approach 0.5 in the examples given here. This is noteworthy because the regions just outside the target volume will receive total doses in the order of 1 Gy, where commensurately high risk factors may not be substantially reduced because of cell kill. Other studies have identified these regions as sites of second cancers. The justification of an imaging regimen might therefore usefully take into account the maximum value of R encountered from the combination of imaging and radiotherapy for particular treatment sites.

Atlas-guided generation of pseudo-CT images for MRI-only and hybrid PET-MRI-guided radiotherapy treatment planning

Science.gov (United States)

Arabi, Hossein; Koutsouvelis, Nikolaos; Rouzaud, Michel; Miralbell, Raymond; Zaidi, Habib

2016-09-01

Magnetic resonance imaging (MRI)-guided attenuation correction (AC) of positron emission tomography (PET) data and/or radiation therapy (RT) treatment planning is challenged by the lack of a direct link between MRI voxel intensities and electron density. Therefore, even if this is not a trivial task, a pseudo-computed tomography (CT) image must be predicted from MRI alone. In this work, we propose a two-step (segmentation and fusion) atlas-based algorithm focusing on bone tissue identification to create a pseudo-CT image from conventional MRI sequences and evaluate its performance against the conventional MRI segmentation technique and a recently proposed multi-atlas approach. The clinical studies consisted of pelvic CT, PET and MRI scans of 12 patients with loco-regionally advanced rectal disease. In the first step, bone segmentation of the target image is optimized through local weighted atlas voting. The obtained bone map is then used to assess the quality of deformed atlases to perform voxel-wise weighted atlas fusion. To evaluate the performance of the method, a leave-one-out cross-validation (LOOCV) scheme was devised to find optimal parameters for the model. Geometric evaluation of the produced pseudo-CT images and quantitative analysis of the accuracy of PET AC were performed. Moreover, a dosimetric evaluation of volumetric modulated arc therapy photon treatment plans calculated using the different pseudo-CT images was carried out and compared to those produced using CT images serving as references. The pseudo-CT images produced using the proposed method exhibit bone identification accuracy of 0.89 based on the Dice similarity metric compared to 0.75 achieved by the other atlas-based method. The superior bone extraction resulted in a mean standard uptake value bias of  -1.5  ±  5.0% (mean  ±  SD) in bony structures compared to  -19.9  ±  11.8% and  -8.1  ±  8.2% achieved by MRI segmentation-based (water

Expected treatment dose construction and adaptive inverse planning optimization: Implementation for offline head and neck cancer adaptive radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Yan Di; Liang Jian [Department of Radiation Oncology, Beaumont Health System, Royal Oak, Michigan 48073 (United States)

2013-02-15

Purpose: To construct expected treatment dose for adaptive inverse planning optimization, and evaluate it on head and neck (h and n) cancer adaptive treatment modification. Methods: Adaptive inverse planning engine was developed and integrated in our in-house adaptive treatment control system. The adaptive inverse planning engine includes an expected treatment dose constructed using the daily cone beam (CB) CT images in its objective and constrains. Feasibility of the adaptive inverse planning optimization was evaluated retrospectively using daily CBCT images obtained from the image guided IMRT treatment of 19 h and n cancer patients. Adaptive treatment modification strategies with respect to the time and the number of adaptive inverse planning optimization during the treatment course were evaluated using the cumulative treatment dose in organs of interest constructed using all daily CBCT images. Results: Expected treatment dose was constructed to include both the delivered dose, to date, and the estimated dose for the remaining treatment during the adaptive treatment course. It was used in treatment evaluation, as well as in constructing the objective and constraints for adaptive inverse planning optimization. The optimization engine is feasible to perform planning optimization based on preassigned treatment modification schedule. Compared to the conventional IMRT, the adaptive treatment for h and n cancer illustrated clear dose-volume improvement for all critical normal organs. The dose-volume reductions of right and left parotid glands, spine cord, brain stem and mandible were (17 {+-} 6)%, (14 {+-} 6)%, (11 {+-} 6)%, (12 {+-} 8)%, and (5 {+-} 3)% respectively with the single adaptive modification performed after the second treatment week; (24 {+-} 6)%, (22 {+-} 8)%, (21 {+-} 5)%, (19 {+-} 8)%, and (10 {+-} 6)% with three weekly modifications; and (28 {+-} 5)%, (25 {+-} 9)%, (26 {+-} 5)%, (24 {+-} 8)%, and (15 {+-} 9)% with five weekly modifications. Conclusions

Image-guided stereotactic radiotherapy for patients with vestibular schwannoma. A clinical study

Energy Technology Data Exchange (ETDEWEB)

Badakhshi, H.; Muellner, S.; Budach, V. [Charite School of Medicine and University Hospital of Berlin, Departments for Radiation Oncology, Berlin (Germany); Wiener, E. [School of Medicine and University Hospital of Berlin, Institute for Neuroradiology, Berlin (Germany)

2014-06-15

Local tumor control and functional outcome after linac-based stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (FSRT) for vestibular schwannoma (VS) were assessed. In all, 250 patients with VS were treated: 190 patients with tumors < 2 cm diameter underwent SRS and 60 patients with tumors >2 to 3.5 cm underwent FSRT. Dose prescription for all cases with SRS (n = 190, 76 %) was 13.5 Gy. For FSRT, mainly two hypofractionated schedules (n = 60, 24 %) with either 7 fractions of 5 Gy (total dose: 35 Gy; n = 35) or 11 fractions of 3.8 Gy (total dose: 41.8 Gy; n = 16) were used. The primary endpoint was local tumor control. Secondary endpoints were symptomatic control and morbidity. The median follow-up was 33.8 months. The 3-year local tumor control was 88.9 %. Local control for SRS and FSRT was 88 and 92 %, respectively. For FSRT with 35 and 41.8 Gy, local control was 90 and 100 %, respectively. There were no acute reactions exceeding grade I. In 61 cases (24.4 % of the entire cohort), trigeminal neuralgia was reported prior to treatment. At last follow-up, 16.3 % (10/61) of those patients reported relief of pain. Regarding facial nerve dysfunction, 45 patients (18 %) presented with symptoms prior to RT. At the last follow-up, 13.3% (6/45) of those patients reported a relief of dysesthesia. Using SRS to treat small VS results in good local control rates. FSRT for larger lesions also seems effective. Severe treatment-related complications are not frequent. Therefore, image-guided stereotactic radiotherapy is an appropriate alternative to microsurgery for patients with VS. (orig.) [German] Wir analysierten die lokale Kontrolle und die funktionellen Verlaeufe bei Patienten mit einem Vestibularisschwannom (VS), die sich einer linacbasierten stereotaktischen Radiochirurgie (SRS) oder einer fraktionierten stereotaktischen Radiotherapie (FSRT) unterzogen. Zwischen 1998 und 2008 wurden 250 Patienten mit einem VS behandelt. In dieser Kohorte wurden 190

A literature review of electronic portal imaging for radiotherapy dosimetry

NARCIS (Netherlands)

van Elmpt, Wouter; McDermott, Leah; Nijsten, Sebastiaan; Wendling, Markus; Lambin, Philippe; Mijnheer, Ben

2008-01-01

Electronic portal imaging devices (EPIDs) have been the preferred tools for verification of patient positioning for radiotherapy in recent decades. Since EPID images contain dose information, many groups have investigated their use for radiotherapy dose measurement. With the introduction of the

Neutrophilia in locally advanced cervical cancer: A novel biomarker for image-guided adaptive brachytherapy?

Science.gov (United States)

Escande, Alexandre; Haie-Meder, Christine; Maroun, Pierre; Gouy, Sébastien; Mazeron, Renaud; Leroy, Thomas; Bentivegna, Enrica; Morice, Philippe; Deutsch, Eric; Chargari, Cyrus

2016-01-01

Objective To study the prognostic value of leucocyte disorders in a prospective cohort of cervical cancer patients receiving definitive chemoradiation plus image—guided adaptive brachytherapy (IGABT). Results 113 patients were identified. All patients received a pelvic irradiation concomitant with chemotherapy, extended to the para-aortic area in 13 patients with IVB disease. Neutrophilia and leukocytosis were significant univariate prognostic factors for poorer local failure-free survival (p = 0.000 and p = 0.002, respectively), associated with tumor size, high-risk clinical target volume (HR-CTV) and anemia. No effect was shown for distant metastases but leukocytosis and neutrophila were both poor prognostic factors for in-field relapses (p = 0.003 and p 7,500/μl (p = 0.018) were independent factors for poorer survival without local failure, with hazard ratio (HR) of 3.1. Materials and methods We examined patients treated in our Institution between April 2009 and July 2015 by concurrent chemoradiation (45 Gy in 25 fractions +/− lymph node boosts) followed by a magnetic resonance imaging (MRI)-guided adaptive pulse-dose rate brachytherapy (15 Gy to the intermediate-risk clinical target volume). The prognostic value of pretreatment leucocyte disorders was examined. Leukocytosis and neutrophilia were defined as a leukocyte count or a neutrophils count exceeding 10,000 and 7,500/μl, respectively. Conclusions Neutrophilia is a significant prognostic factor for local relapse in locally advanced cervical cancer treated with MRI-based IGABT. This biomarker could help identifying patients with higher risk of local relapse and requiring dose escalation. PMID:27713124

Tissue feature-based intra-fractional motion tracking for stereoscopic x-ray image guided radiotherapy

Science.gov (United States)

Xie, Yaoqin; Xing, Lei; Gu, Jia; Liu, Wu

2013-06-01

Real-time knowledge of tumor position during radiation therapy is essential to overcome the adverse effect of intra-fractional organ motion. The goal of this work is to develop a tumor tracking strategy by effectively utilizing the inherent image features of stereoscopic x-ray images acquired during dose delivery. In stereoscopic x-ray image guided radiation delivery, two orthogonal x-ray images are acquired either simultaneously or sequentially. The essence of markerless tumor tracking is the reliable identification of inherent points with distinct tissue features on each projection image and their association between two images. The identification of the feature points on a planar x-ray image is realized by searching for points with high intensity gradient. The feature points are associated by using the scale invariance features transform descriptor. The performance of the proposed technique is evaluated by using images of a motion phantom and four archived clinical cases acquired using either a CyberKnife equipped with a stereoscopic x-ray imaging system, or a LINAC equipped with an onboard kV imager and an electronic portal imaging device. In the phantom study, the results obtained using the proposed method agree with the measurements to within 2 mm in all three directions. In the clinical study, the mean error is 0.48 ± 0.46 mm for four patient data with 144 sequential images. In this work, a tissue feature-based tracking method for stereoscopic x-ray image guided radiation therapy is developed. The technique avoids the invasive procedure of fiducial implantation and may greatly facilitate the clinical workflow.

Tissue feature-based intra-fractional motion tracking for stereoscopic x-ray image guided radiotherapy

International Nuclear Information System (INIS)

Xie Yaoqin; Gu Jia; Xing Lei; Liu Wu

2013-01-01

Real-time knowledge of tumor position during radiation therapy is essential to overcome the adverse effect of intra-fractional organ motion. The goal of this work is to develop a tumor tracking strategy by effectively utilizing the inherent image features of stereoscopic x-ray images acquired during dose delivery. In stereoscopic x-ray image guided radiation delivery, two orthogonal x-ray images are acquired either simultaneously or sequentially. The essence of markerless tumor tracking is the reliable identification of inherent points with distinct tissue features on each projection image and their association between two images. The identification of the feature points on a planar x-ray image is realized by searching for points with high intensity gradient. The feature points are associated by using the scale invariance features transform descriptor. The performance of the proposed technique is evaluated by using images of a motion phantom and four archived clinical cases acquired using either a CyberKnife equipped with a stereoscopic x-ray imaging system, or a LINAC equipped with an onboard kV imager and an electronic portal imaging device. In the phantom study, the results obtained using the proposed method agree with the measurements to within 2 mm in all three directions. In the clinical study, the mean error is 0.48 ± 0.46 mm for four patient data with 144 sequential images. In this work, a tissue feature-based tracking method for stereoscopic x-ray image guided radiation therapy is developed. The technique avoids the invasive procedure of fiducial implantation and may greatly facilitate the clinical workflow. (paper)

Imaged-guided liver stereotactic body radiotherapy using VMAT and real-time adaptive tumor gating. Concerns about technique and preliminary clinical results.

Science.gov (United States)

Llacer-Moscardo, Carmen; Riou, Olivier; Azria, David; Bedos, Ludovic; Ailleres, Norbert; Quenet, Francois; Rouanet, Philippe; Ychou, Marc; Fenoglietto, Pascal

2017-01-01

Motion management is a major challenge in abdominal SBRT. We present our study of SBRT for liver tumors using intrafraction motion review (IMR) allowing simultaneous KV information and MV delivery to synchronize the beam during gated RapidArc treatment. Between May 2012 and March 2015, 41 patients were treated by liver SBRT using gated RapidArc technique in a Varian Novalis Truebeam STx linear accelerator. PTV was created by expanding 5 mm from the ITV. Dose prescription ranged from 40 to 50 Gy in 5-10 fractions. The prescribed dose and fractionation were chosen depending on hepatic function and dosimetric results. Thirty-four patients with a minimal follow-up of six months were analyzed for local control and toxicity. Accuracy for tumor repositioning was evaluated for the first ten patients. With a median follow-up of 13 months, the treatment was well tolerated and no patient presented RILD, perforation or gastrointestinal bleeding. Acute toxicity was found in 3 patients with G1 abdominal pain, 2 with G1 nausea, 10 with G1 asthenia and 1 with G2 asthenia. 6 patients presented asymptomatic transitory perturbation of liver enzymes. In-field local control was 90.3% with 7 complete responses, 14 partial responses and 7 stabilisations. 3 patients evolved "in field". 12 patients had an intrahepatic progression "out of field". Mean intrafraction deviation of fiducials in the craneo-caudal direction was 0.91 mm (0-6 mm). The clinical tolerance and oncological outcomes were favorable when using image-guided liver SBRT with real-time adaptive tumor gating.

Towards multidimensional radiotherapy (MD-CRT): biological imaging and biological conformality

International Nuclear Information System (INIS)

Ling, C. Clifton; Humm, John; Larson, Steven; Amols, Howard; Fuks, Zvi; Leibel, Steven; Koutcher, Jason A.

2000-01-01

Purpose: The goals of this study were to survey and summarize the advances in imaging that have potential applications in radiation oncology, and to explore the concept of integrating physical and biological conformality in multidimensional conformal radiotherapy (MD-CRT). Methods and Materials: The advances in three-dimensional conformal radiotherapy (3D-CRT) have greatly improved the physical conformality of treatment planning and delivery. The development of intensity-modulated radiotherapy (IMRT) has provided the 'dose painting' or 'dose sculpting' ability to further customize the delivered dose distribution. The improved capabilities of nuclear magnetic resonance imaging and spectroscopy, and of positron emission tomography, are beginning to provide physiological and functional information about the tumor and its surroundings. In addition, molecular imaging promises to reveal tumor biology at the genotype and phenotype level. These developments converge to provide significant opportunities for enhancing the success of radiotherapy. Results: The ability of IMRT to deliver nonuniform dose patterns by design brings to fore the question of how to 'dose paint' and 'dose sculpt', leading to the suggestion that 'biological' images may be of assistance. In contrast to the conventional radiological images that primarily provide anatomical information, biological images reveal metabolic, functional, physiological, genotypic, and phenotypic data. Important for radiotherapy, the new and noninvasive imaging methods may yield three-dimensional radiobiological information. Studies are urgently needed to identify genotypes and phenotypes that affect radiosensitivity, and to devise methods to image them noninvasively. Incremental to the concept of gross, clinical, and planning target volumes (GTV, CTV, and PTV), we propose the concept of 'biological target volume' (BTV) and hypothesize that BTV can be derived from biological images and that their use may incrementally improve

The situation of radiotherapy in 2011

International Nuclear Information System (INIS)

2012-06-01

Published within the frame of the French 2009-2013 cancer plan, this report proposes an analysis of the situation of radiotherapy in France. More particularly, it analyses the French offer in terms of radiotherapy treatments and the French position in Europe. A second part analyses equipment (accelerators and other equipment) and techniques aimed at radiotherapy treatment preparation and delivery. The following techniques are addressed: three-dimensional conformational, intensity modulation, intracranial and extracranial stereotactic, image-guided, total body irradiation, hadron-therapy, and peri-operative radiotherapy. The last parts analyse the activity of radiotherapy centres in terms of treated patients, of patient age structure, of sessions and preparations, and of treated pathologies, the medical and paramedical personnel in charge of radiotherapy, and financial and cost aspects

Guidelines for primary radiotherapy of patients with prostate cancer

International Nuclear Information System (INIS)

Boehmer, Dirk; Maingon, Philippe; Poortmans, Philip; Baron, Marie-Helene; Miralbell, Raymond; Remouchamps, Vincent; Scrase, Christopher; Bossi, Alberto; Bolla, Michel

2006-01-01

Background and purposes: The appropriate application of 3-D conformal radiotherapy, intensity modulated radiotherapy or image guided radiotherapy for patients undergoing radiotherapy for prostate cancer requires a standardisation of target delineation as well as clinical quality assurance procedures. Patients and methods: Pathological and imaging studies provide valuable information on tumour extension. In addition, clinical investigations on patient positioning and immobilisation as well as treatment verification data offer an abundance of information. Results: Target volume definitions for different risk groups of prostate cancer patients based on pathological and imaging studies are provided. Available imaging modalities, patient positioning and treatment preparation studies as well as verification procedures are collected from literature studies. These studies are summarised and recommendations are given where appropriate. Conclusions: On behalf of the European Organisation for Research and Treatment of Cancer (EORTC) Radiation Oncology Group this article presents a common set of recommendations for external beam radiotherapy of patients with prostate cancer

Late toxicity and biochemical control in 554 prostate cancer patients treated with and without dose escalated image guided radiotherapy

International Nuclear Information System (INIS)

Kok, David; Gill, Suki; Bressel, Mathias; Byrne, Keelan; Kron, Tomas; Fox, Chris; Duchesne, Gillian; Tai, Keen Hun; Foroudi, Farshad

2013-01-01

Background and purpose: To compare rates of late gastrointestinal toxicity, late genitourinary toxicity and biochemical failure between patients treated for prostate cancer with implanted fiducial marker image guided radiotherapy (FMIGRT), and those treated without FMIGRT. Methods and materials: We performed a single institution retrospective study comparing all 311 patients who received 74 Gy without fiducial markers in 2006 versus all 243 patients who received our updated regimen of 78 Gy with FMIGRT in 2008. Patient records were reviewed 27 months after completing radiotherapy. Biochemical failure was defined using the Phoenix definition. Details of late gastrointestinal and genitourinary toxicities were graded according to CTCAEv4. Moderate/severe toxicity was defined as a grade 2 or higher toxicity. Cumulative incidence and prevalence curves for moderate/severe toxicity were constructed and compared using multistate modeling while biochemical failure free survival was compared using the log rank test. A Cox regression model was developed to correct for confounding factors. Results: Median follow-up time for both groups was 22 months. The hazard ratio for moderate/severe late gastrointestinal toxicity in the non-FMIGRT group was 3.66 [95% CI (1.63–8.23), p = 0.003] compared to patients in the FMIGRT group. There was no difference in the hazard ratio of moderate/severe late genitourinary toxicity between the two groups (0.44 [95% CI (0.19–1.00)]), but patients treated with FMIGRT did have a quicker recovery from their genitourinary toxicities HR = 0.24 [95% CI (0.10–0.59)]. We were unable to detect any differences in biochemical failure free survival between the cohorts HR = 0.60 [95% CI (0.30–1.20), p = 0.143]. Conclusion: Despite dose escalation, the use of FMIGRT in radical radiotherapy for prostate cancer significantly reduces the incidence of gastrointestinal toxicity and the duration of late genitourinary toxicity when compared to conventional non

Treatment outcome of high-dose image-guided intensity-modulated radiotherapy using intra-prostate fiducial markers for localized prostate cancer at a single institute in Japan

International Nuclear Information System (INIS)

Takeda, Ken; Shimizu, Eiji; Abe, Keiko; Shirata, Yuko; Ishikawa, Yohjiro

2012-01-01

Several studies have confirmed the advantages of delivering high doses of external beam radiotherapy to achieve optimal tumor-control outcomes in patients with localized prostate cancer. We evaluated the medium-term treatment outcome after high-dose, image-guided intensity-modulated radiotherapy (IMRT) using intra-prostate fiducial markers for clinically localized prostate cancer. In total, 141 patients with localized prostate cancer treated with image-guided IMRT (76 Gy in 13 patients and 80 Gy in 128 patients) between 2003 and 2008 were enrolled in this study. The patients were classified according to the National Comprehensive Cancer Network-defined risk groups. Thirty-six intermediate-risk patients and 105 high-risk patients were included. Androgen-deprivation therapy was performed in 124 patients (88%) for a median of 11 months (range: 2–88 months). Prostate-specific antigen (PSA) relapse was defined according to the Phoenix-definition (i.e., an absolute nadir plus 2 ng/ml dated at the call). The 5-year actuarial PSA relapse-free survival, the 5-year distant metastasis-free survival, the 5-year cause-specific survival (CSS), the 5-year overall survival (OS) outcomes and the acute and late toxicities were analyzed. The toxicity data were scored according to the Common Terminology Criteria for Adverse Events, version 4.0. The median follow-up was 60 months. The 5-year PSA relapse-free survival rates were 100% for the intermediate-risk patients and 82.2% for the high-risk patients; the 5-year actuarial distant metastasis-free survival rates were 100% and 95% for the intermediate- and high-risk patients, respectively; the 5-year CSS rates were 100% for both patient subsets; and the 5-year OS rates were 100% and 91.7% for the intermediate- and high-risk patients, respectively. The Gleason score (<8 vs. ≥8) was significant for the 5-year PSA relapse-free survival on multivariate analysis (p = 0.044). There was no grade 3 or 4 acute toxicity. The incidence of

Organization and visualization of medical images in radiotherapy

International Nuclear Information System (INIS)

Lorang, T.

2001-05-01

In modern radiotherapy, various imaging equipment is used to acquire views from inside human bodies. Tomographic imaging equipment is acquiring stacks of cross-sectional images, software implementations derive three-dimensional volumes from planar images to allow for visualization of reconstructed cross-sections at any orientation and location and higher-level visualization systems allow for transparent views and surface rendering. Of upcoming interest in radiotherapy is mutual information, the integration of information from multiple imaging equipment res. from the same imaging equipment at different time stamps and varying acquisition parameters. Huge amounts of images are acquired nowadays at radiotherapy centers, requiring organization of images with respect to patient, acquisition and equipment to allow for visualization of images in a comparative and integrative manner. Especially for integration of image information from different equipment, geometrical information is required to allow for registration of images res. volumes. DICOM 3.0 has been introduced as a standard for information interchange with respect to medical imaging. Geometric information of cross-sections, demographic information of patients and medical information of acquisitions and equipment are covered by this standard, allowing for a high-level automation with respect to organization and visualization of medical images. Reconstructing cross-sectional images from volumes at any orientation and location is required for the purpose of registration and multi-planar views. Resampling and addressing of discrete volume data need be implemented efficiently to allow for simultaneous visualization of multiple cross-sectional images, especially with respect to multiple, non-isotropy volume data sets. (author)

Method for automatic re contouring straight adaptive radiotherapy for prostate cancer; Metodo para el recontorneo automatico del recto en radioterapia adaptativa en cancer de prostata

Energy Technology Data Exchange (ETDEWEB)

Rodriguez Vila, B.; Garcia Vicente, F.; Aguilera, E. J.

2011-07-01

Outline of quickly and accurately the rectal wall is important in Image Guided Radiotherapy (IGRT in the acronym) as an organ of greatest influence in limiting the dose in the planning of radiation therapy in prostate cancer. Deformabies registration methods based on image intensity can not create a correct spatial transformation if there is no correspondence between the image and image planning session. The rectal content variation creates a non-correspondence in the image intensity becomes a major obstacle to the deformable registration based on image intensity.

Combined Inter- and Intrafractional Plan Adaptation Using Fraction Partitioning in Magnetic Resonance-guided Radiotherapy Delivery.

Science.gov (United States)

Lagerwaard, Frank; Bohoudi, Omar; Tetar, Shyama; Admiraal, Marjan A; Rosario, Tezontl S; Bruynzeel, Anna

2018-04-05

Magnetic resonance-guided radiation therapy (MRgRT) not only allows for superior soft-tissue setup and online MR-guidance during delivery but also for inter-fractional plan re-optimization or adaptation. This plan adaptation involves repeat MR imaging, organs at risk (OARs) re-contouring, plan prediction (i.e., recalculating the baseline plan on the anatomy of that moment), plan re-optimization, and plan quality assurance. In contrast, intrafractional plan adaptation cannot be simply performed by pausing delivery at any given moment, adjusting contours, and re-optimization because of the complex and composite nature of deformable dose accumulation. To overcome this limitation, we applied a practical workaround by partitioning treatment fractions, each with half the original fraction dose. In between successive deliveries, the patient remained in the treatment position and all steps of the initial plan adaptation were repeated. Thus, this second re-optimization served as an intrafractional plan adaptation at 50% of the total delivery. The practical feasibility of this partitioning approach was evaluated in a patient treated with MRgRT for locally advanced pancreatic cancer (LAPC). MRgRT was delivered in 40Gy in 10 fractions, with two fractions scheduled successively on each treatment day. The contoured gross tumor volume (GTV) was expanded by 3 mm, excluding parts of the OARs within this expansion to derive the planning target volume for daily re-optimization (PTV OPT ). The baseline GTVV 95%  achieved in this patient was 80.0% to adhere to the high-dose constraints for the duodenum, stomach, and bowel (V 33 Gy ViewRay Inc, Mountain View, USA) using video-assisted breath-hold in shallow inspiration. The dual plan adaptation resulted, for each partitioned fraction, in the generation of Plan PREDICTED1 , Plan RE-OPTIMIZED1  (inter-fractional adaptation), Plan PREDICTED2 , and Plan RE-OPTIMIZED2  (intrafractional adaptation). An offline analysis was

Comprehensive evaluation of ten deformable image registration algorithms for contour propagation between CT and cone-beam CT images in adaptive head & neck radiotherapy.

Science.gov (United States)

Li, Xin; Zhang, Yuyu; Shi, Yinghua; Wu, Shuyu; Xiao, Yang; Gu, Xuejun; Zhen, Xin; Zhou, Linghong

2017-01-01

Deformable image registration (DIR) is a critical technic in adaptive radiotherapy (ART) for propagating contours between planning computerized tomography (CT) images and treatment CT/cone-beam CT (CBCT) images to account for organ deformation for treatment re-planning. To validate the ability and accuracy of DIR algorithms in organ at risk (OAR) contour mapping, ten intensity-based DIR strategies, which were classified into four categories-optical flow-based, demons-based, level-set-based and spline-based-were tested on planning CT and fractional CBCT images acquired from twenty-one head & neck (H&N) cancer patients who underwent 6~7-week intensity-modulated radiation therapy (IMRT). Three similarity metrics, i.e., the Dice similarity coefficient (DSC), the percentage error (PE) and the Hausdorff distance (HD), were employed to measure the agreement between the propagated contours and the physician-delineated ground truths of four OARs, including the vertebra (VTB), the vertebral foramen (VF), the parotid gland (PG) and the submandibular gland (SMG). It was found that the evaluated DIRs in this work did not necessarily outperform rigid registration. DIR performed better for bony structures than soft-tissue organs, and the DIR performance tended to vary for different ROIs with different degrees of deformation as the treatment proceeded. Generally, the optical flow-based DIR performed best, while the demons-based DIR usually ranked last except for a modified demons-based DISC used for CT-CBCT DIR. These experimental results suggest that the choice of a specific DIR algorithm depends on the image modality, anatomic site, magnitude of deformation and application. Therefore, careful examinations and modifications are required before accepting the auto-propagated contours, especially for automatic re-planning ART systems.

Prostate bed motion may cause geographic miss in post-prostatectomy image-guided intensity-modulated radiotherapy

International Nuclear Information System (INIS)

Bell, Linda J.; Cox, Jennifer; Eade, Thomas; Rinks, Marianne; Kneebone, Andrew

2013-01-01

There is little data to guide radiation oncologists on appropriate margin selection in the post-prostatectomy setting. The aim of this study was to quantify interfraction variation in motion of the prostate bed to determine these margins. The superior and inferior surgical clips in the prostate bed were tracked on pretreatment cone beam CT images (n=377) for 40 patients who had received post-prostatectomy radiotherapy. Prostate bed motion was calculated for the upper and lower segments by measuring the position of surgical clips located close to midline relative to bony anatomy in the axial (translational) and sagittal (tilt) planes. The frequency of potential geographic misses was calculated for either 1cm or 0.5cm posterior planning target volume margins. The mean magnitude of movement of the prostate bed in the anterior–posterior, superior–inferior and left–right planes, respectively, were as follows: upper portion, 0.50cm, 0.28cm, 0.10cm; lower portion, 0.18cm, 0.18cm, 0.08cm. The random and systematic errors, respectively, of the prostate bed motion in the anterior–posterior, superior–inferior and left–right planes, respectively, were as follows: upper portion, 0.47cm and 0.50cm, 0.28cm and 0.27cm, 0.11cm and 0.11cm; lower portion, 0.17cm and 18cm, 0.17cm and 0.19cm, 0.08cm and 0.10cm. Most geographic misses occurred in the upper prostate bed in the anterior–posterior plane. The median prostate bed tilt was 1.8° (range −23.4° to 42.3°). Variability was seen in all planes for the movement of both surgical clips. The greatest movement occurred in the anterior–posterior plane in the upper prostate bed, which could cause geographic miss of treatment delivery. The variability in the movement of the superior and inferior clips indicates a prostate bed tilt that would be difficult to correct with standard online matching techniques. This creates a strong argument for using anisotropic planning target volume margins in post

Application of CT perfusion imaging in radiotherapy for lung cancer

International Nuclear Information System (INIS)

Xia Guangrong; Liu Guimei; He Wen; Jin Guohua; Xie Ruming; Xu Yongxiang; Li Xiaobo; Li Xuebing

2011-01-01

Objective: To investigate the value of CT perfusion imaging in evaluation of therapeutic effect and prognosis in radiotherapy for lung cancer. Methods: Fifty-one cases of lung cancer who were unable or refused to be operated on, 36 males and 15 females, aged 37-80, underwent CT perfusion imaging, 29 of which only before radiotherapy and 22 before and after radiotherapy twice. The images were collected by cine dynamic scanning (5 mm/4 slices) and input into the GE AW4.0 workstation for data processing. The slice positions of CT imaging were determined according to the largest tumor size in CT scan. Regions of interest of tumor were drawn at the region corresponding to the original images of CT perfusion. Radiotherapy was performed after CT perfusion imaging. Relevant parameters, including blood flow (BF), blood volume (BV), mean transit time (MTT), and permeability surface (PS) were calculated. The treatment response after radiotherapy was evaluated by RECIST. At 2 -4 weeks after the treatment, CT examination was conducted once more. Results: The tests of the 51 patients showed that the BV was 13.6 ml·100 g -1 , the BF was 129.5 ml·min -1 ·100 g -1 , the MTT was 9.1 s, and the PS was 10.0 ml· min -1 · 100 g -1 before radiotherapy. The tests of the 22 of the 51 patients showed that the values of BV and BF after radiotherapy were 7.6 ml· 100 g -1 and 97.8 ml·min -1 · 100 g -1 , respectively, both lower than those before radiotherapy (11.2 and 108.7 ml·min -1 ·100 g -1 , respectively), however, both not significantly (t=1.28, 0.40, P>0.05); and the values of MTT and PS after radiotherapy were 8.9 s and 7.8 ml·min -1 · 100 g -1 , respectively, both not significantly higher than those before radiotherapy (7.2 s and 6.8 ml· min -1 · 100 g -1 , respectively, t=-1.15, -0.57, P>0.05). The mean area of tumor after radiotherapy was 1189.6 mm 2 , significantly less than that before radiotherapy (1920.3 mm 2 , t=3.98, P<0.05). The MTT of the SCLC patients was 12

Curent requirements for image management in radiotherapy

International Nuclear Information System (INIS)

Steil, V.; Schneider, F.; Wenz, F.; Lohr, F.; Roehner, F.; Weisser, G.

2012-01-01

Treatment techniques of increasing complexity such as dynamic/rotational techniques mandate digital management and increasingly image guidance. This constantly increases requirements for image management and archiving. This article discusses the current status of these requirements and will present potential image administration strategies. Fundamentals of image administration and storage/archiving are presented (DICOM Standard, radiotherapy-specific issues) along the typical patient pathway (demographic data, radiotherapy treatment planning, signatures/approval of plan and image data, archiving of plan and image data). Different strategies for image management are presented (archiving centered on individual application vs. integral approach with central archiving in a DICOM-RT-PACS governed by a radiation oncology information system (ROCIS)). Infrastructural requirements depending on the amount of image data generated in the department are discussed. Application-centered image management provides access to image data including all relevant RT-specific elements. This approach, however, is not migration-safe, requires significant administrative work to ensure a redundancy level that protects against data loss and does not provide datasets that are linked to respective therapeutic interventions. Therefore, centralized image management and archiving that links images to patients and individual steps in the treatment pathway within a standardized DICOM(-RT) environment is preferable despite occasional problems with visualization of specific data elements. (orig.)

Imaging and dosimetric errors in 4D PET/CT-guided radiotherapy from patient-specific respiratory patterns: a dynamic motion phantom end-to-end study.

Science.gov (United States)

Bowen, S R; Nyflot, M J; Herrmann, C; Groh, C M; Meyer, J; Wollenweber, S D; Stearns, C W; Kinahan, P E; Sandison, G A

2015-05-07

of errors was comparable during PET/CT imaging and treatment delivery without motion compensation. Errors were moderately mitigated during PET/CT imaging and significantly mitigated during RT delivery with motion compensation. This dynamic motion phantom end-to-end workflow provides a method for quality assurance of 4D PET/CT-guided radiotherapy, including evaluation of respiratory motion compensation methods during imaging and treatment delivery.

A tri-modality image fusion method for target delineation of brain tumors in radiotherapy.

Directory of Open Access Journals (Sweden)

Lu Guo

Full Text Available To develop a tri-modality image fusion method for better target delineation in image-guided radiotherapy for patients with brain tumors.A new method of tri-modality image fusion was developed, which can fuse and display all image sets in one panel and one operation. And a feasibility study in gross tumor volume (GTV delineation using data from three patients with brain tumors was conducted, which included images of simulation CT, MRI, and 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET examinations before radiotherapy. Tri-modality image fusion was implemented after image registrations of CT+PET and CT+MRI, and the transparency weight of each modality could be adjusted and set by users. Three radiation oncologists delineated GTVs for all patients using dual-modality (MRI/CT and tri-modality (MRI/CT/PET image fusion respectively. Inter-observer variation was assessed by the coefficient of variation (COV, the average distance between surface and centroid (ADSC, and the local standard deviation (SDlocal. Analysis of COV was also performed to evaluate intra-observer volume variation.The inter-observer variation analysis showed that, the mean COV was 0.14(± 0.09 and 0.07(± 0.01 for dual-modality and tri-modality respectively; the standard deviation of ADSC was significantly reduced (p<0.05 with tri-modality; SDlocal averaged over median GTV surface was reduced in patient 2 (from 0.57 cm to 0.39 cm and patient 3 (from 0.42 cm to 0.36 cm with the new method. The intra-observer volume variation was also significantly reduced (p = 0.00 with the tri-modality method as compared with using the dual-modality method.With the new tri-modality image fusion method smaller inter- and intra-observer variation in GTV definition for the brain tumors can be achieved, which improves the consistency and accuracy for target delineation in individualized radiotherapy.

Multi-institutional MicroCT image comparison of image-guided small animal irradiators

Science.gov (United States)

Johnstone, Chris D.; Lindsay, Patricia; E Graves, Edward; Wong, Eugene; Perez, Jessica R.; Poirier, Yannick; Ben-Bouchta, Youssef; Kanesalingam, Thilakshan; Chen, Haijian; E Rubinstein, Ashley; Sheng, Ke; Bazalova-Carter, Magdalena

2017-07-01

was less than 20 s. We present image quality assurance recommendations for image-guided small animal radiotherapy systems that can aid researchers in maintaining high image quality, allowing for spatially precise conformal dose delivery to small animals.

SU-F-T-529: Dosimetric Investigation of a Rotating Gamma Ray System for ImagedGuided Modulated Arc Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Ma, C; Chibani, O; Eldib, A; Chen, L [Fox Chase Cancer Center, Philadelphia, PA (United States); Li, J [Cyber Medical Inc, Xian (China)

2016-06-15

Purpose: Because of their effectiveness and efficiency, rotational arc radiotherapy (MAT) techniques have been developed on both specialty machines such as Tomotherapy and conventional linear accelerators. This work investigates a new rotating Gamma therapy system for image guided MAT and SBRT of intra/extracranial tumors. Methods: The CyberMAT system (Cyber Medical Corp., China) consists of a ring gantry with a gamma source (effective source size 1cm and 1.7cm respectively), a 120-leaf MLC, a kV CBCT and an EPID. The treatment couch provides 6-degrees-of-freedom motion compensation and the kV CBCT system has a spatial resolution of 0.4mm for target localization. The maximum dose rate is >4.0 Gy/min and the maximum field size is 40cm × 40cm. Monte Carlo simulations were used to compute dose distributions and compare with measurements. A retrospective study of 125 previously treated SBRT patients was performed to evaluate the dosimetric characteristics of CyberMAT in comparison with existing VMAT systems. Results: Monte Carlo results confirmed the CyberMAT design parameters including output factors and 3D dose distributions. Its beam penumbra is 5mm to 10mm for field sizes 1cm to 10cm, respectively and its isocenter accuracy is <0.5mm. Compared to the 6 MV photons of Tomotherapy and conventional linacs, Cobalt beams produce lower-energy secondary electrons that exhibit better dose properties in low-density lung tissues. Cobalt beams are ideal for peripheral lung tumors with half-arc arrangements to spare the opposite lung and other critical structures. Superior dose distributions have been obtained for brain, head and neck, breast, spine and lung tumors with half/full arc arrangements. Conclusion: Because of the unique dosimetric properties of Cobalt sources and its accurate stereotaxy/dose delivery CyberMAT is ideally suited for image guided MAT and SBRT. Full-arc arrangements are superior for brain and H&N treatments while half-arc arrangements produce best dose

Dosimetric evaluation of the OneDoseTM MOSFET for measuring kilovoltage imaging dose from image-guided radiotherapy procedures.

Science.gov (United States)

Ding, George X; Coffey, Charles W

2010-09-01

The purpose of this study is to investigate the feasibility of using a single-use dosimeter, OneDose MOSFET designed for in vivo patient dosimetry, for measuring the radiation dose from kilovoltage (kV) x rays resulting from image-guided procedures. The OneDose MOSFET dosimeters were precalibrated by the manufacturer using Co-60 beams. Their energy response and characteristics for kV x rays were investigated by using an ionization chamber, in which the air-kerma calibration factors were obtained from an Accredited Dosimetry Calibration Laboratory (ADCL). The dosimetric properties have been tested for typical kV beams used in image-guided radiation therapy (IGRT). The direct dose reading from the OneDose system needs to be multiplied by a correction factor ranging from 0.30 to 0.35 for kilovoltage x rays ranging from 50 to 125 kVp, respectively. In addition to energy response, the OneDose dosimeter has up to a 20% reduced sensitivity for beams (70-125 kVp) incident from the back of the OneDose detector. The uncertainty in measuring dose resulting from a kilovoltage beam used in IGRT is approximately 20%; this uncertainty is mainly due to the sensitivity dependence of the incident beam direction relative to the OneDose detector. The ease of use may allow the dosimeter to be suitable for estimating the dose resulting from image-guided procedures.

Patient repositioning in prostate conformal radiotherapy by image fusion

International Nuclear Information System (INIS)

Betrouni, Nacim

2004-01-01

This research thesis first proposes an overview of imaging modalities which are generally used in radiotherapy, and briefly presents operation principles for ultrasound scans, scanners and MRI. The issue of patient repositioning in radiotherapy is then introduced, and already proposed solutions are presented. In the next part, the author addresses space location and ultrasound-based location, with a brief overview of methods used to track the displacements of a mobile object, in this case an ultrasound probe, and calibration. Then, after a presentation of the adopted method, and a discussion of published works related to contour extraction and to filtering and noise reduction methods in ultrasound imagery, the author addresses the issue of prostate segmentation based on ultrasound images. The next part deals with image registration with an overview of available methods and tools. A method of registration of pre-operation images obtained by MRI or scanner, and of intra-operation ultrasound images is proposed for a real-time registration. This method is aimed at supporting patient repositioning during prostate conformal radiotherapy

Image guided adaptive brachytherapy with combined intracavitary and interstitial technique improves the therapeutic ratio in locally advanced cervical cancer: Analysis from the retroEMBRACE study

DEFF Research Database (Denmark)

LU, Fokdal; Sturdza, Alina; Mazeron, Renaud

2016-01-01

Background and purpose Image guided adaptive brachytherapy (IGABT) using intracavitary applicators (IC) has led to a significant improvement of local control in locally advanced cervical cancer (LACC). Further improvement has been obtained with combined intracavitary/interstitial (IC/IS) applicat...... IC/IS brachytherapy improves the therapeutic ratio in LACC by enabling a tumour specific dose escalation resulting in significantly higher local control in large tumours without adding treatment related late morbidity.......Background and purpose Image guided adaptive brachytherapy (IGABT) using intracavitary applicators (IC) has led to a significant improvement of local control in locally advanced cervical cancer (LACC). Further improvement has been obtained with combined intracavitary/interstitial (IC....../IS) applicators. The aim of this analysis was to evaluate the impact on local control and late morbidity of application of combined IS/IC brachytherapy in a large multicentre population. Material/methods 610 patients with LACC from the retroEMBRACE study were included. Patients were divided into an IC group (N...

Multiple comparisons permutation test for image based data mining in radiotherapy

NARCIS (Netherlands)

Chen, Chun; Witte, Marnix; Heemsbergen, Wilma; van Herk, Marcel

2013-01-01

: Comparing incidental dose distributions (i.e. images) of patients with different outcomes is a straightforward way to explore dose-response hypotheses in radiotherapy. In this paper, we introduced a permutation test that compares images, such as dose distributions from radiotherapy, while tackling

WE-G-BRF-06: Positron Emission Tomography (PET)-Guided Dynamic Lung Tumor Tracking for Cancer Radiotherapy: First Patient Simulations

International Nuclear Information System (INIS)

Yang, J; Loo, B; Graves, E; Yamamoto, T; Keall, P

2014-01-01

Purpose: PET-guided dynamic tumor tracking is a novel concept of biologically targeted image guidance for radiotherapy. A dynamic tumor tracking algorithm based on list-mode PET data has been developed and previously tested on dynamic phantom data. In this study, we investigate if dynamic tumor tracking is clinically feasible by applying the method to lung cancer patient PET data. Methods: PET-guided tumor tracking estimates the target position of a segmented volume in PET images reconstructed continuously from accumulated coincidence events correlated with external respiratory motion, simulating real-time applications, i.e., only data up to the current time point is used to estimate the target position. A target volume is segmented with a 50% threshold, consistently, of the maximum intensity in the predetermined volume of interest. Through this algorithm, the PET-estimated trajectories are quantified from four lung cancer patients who have distinct tumor location and size. The accuracy of the PET-estimated trajectories is evaluated by comparing to external respiratory motion because the ground-truth of tumor motion is not known in patients; however, previous phantom studies demonstrated sub-2mm accuracy using clinically derived 3D tumor motion. Results: The overall similarity of motion patterns between the PET-estimated trajectories and the external respiratory traces implies that the PET-guided tracking algorithm can provide an acceptable level of targeting accuracy. However, there are variations in the tracking accuracy between tumors due to the quality of the segmentation which depends on target-to-background ratio, tumor location and size. Conclusion: For the first time, a dynamic tumor tracking algorithm has been applied to lung cancer patient PET data, demonstrating clinical feasibility of real-time tumor tracking for integrated PET-linacs. The target-to-background ratio is a significant factor determining accuracy: screening during treatment planning would

Present status and future of high-precision image guided adaptive brachytherapy for cervix carcinoma

International Nuclear Information System (INIS)

Poetter, Richard; Kirisits, Christian; Fidarova, Elena F.; Dimopoulos, Johan nes C. A.; Berger, Daniel; Tanderup, Kari; Lindegaard, Jacob C.

2008-01-01

Introduction. Image guided adaptive brachytherapy (IGABT) for cervical cancer, using mainly MRI, is an evolving method, increasingly replacing the 2D approach based on conventional radiography. During the complex 4D chain of this procedure image-assistance is provided for disease assessment, provisional treatment planning ('pre-planning'), applicator placement and reconstruction, as well as for contouring, definitive treatment planning and quality control of dose delivery. With IGABT changes of topography adjacent to the applicator, caused by tumour regression, oedema, organ changes and dilation are identified. Thus, the CTV for IGABT is primarily based on the tumour volume at the time of BT and takes into account both time and spatial domains. IGABT requires systematic concepts for target, OAR, biological modelling, DVH analysis, and dose-volume-adaptation. Methods and Results. This report focuses on the advantages and uncertainties, dose-effect relations and clinical results of the IGABT procedure addressing the current status and future perspectives. Uncertainties during the 4D chain of IGABT are mainly related to target contouring, applicator reconstruction, as well as to inter-fraction, intra-fraction and inter-application variability, as caused by tumour response and organ changes. Different from EBRT where set-up uncertainties are compensated by adding a margin to the CTV, no margins to the lateral and anterior-posterior directions can be used for IGABT. Discussion. By 3D treatment planning for IGABT significant improvement of the DVH parameters is achieved compared to 2D library plans. In small tumours the benefit is primarily obtained by a decrease of dose to nearby OAR while in large tumours the use of supplementary interstitial techniques and optimization may double the target volume that can be treated at a therapeutic dose level. The clinical impact of IGABT could recently be demonstrated by the establishment of some correlations between target- and

SU-D-BRB-05: Quantum Learning for Knowledge-Based Response-Adaptive Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

El Naqa, I; Ten, R [Haken University of Michigan, Ann Arbor, MI (United States)

2016-06-15

Purpose: There is tremendous excitement in radiotherapy about applying data-driven methods to develop personalized clinical decisions for real-time response-based adaptation. However, classical statistical learning methods lack in terms of efficiency and ability to predict outcomes under conditions of uncertainty and incomplete information. Therefore, we are investigating physics-inspired machine learning approaches by utilizing quantum principles for developing a robust framework to dynamically adapt treatments to individual patient’s characteristics and optimize outcomes. Methods: We studied 88 liver SBRT patients with 35 on non-adaptive and 53 on adaptive protocols. Adaptation was based on liver function using a split-course of 3+2 fractions with a month break. The radiotherapy environment was modeled as a Markov decision process (MDP) of baseline and one month into treatment states. The patient environment was modeled by a 5-variable state represented by patient’s clinical and dosimetric covariates. For comparison of classical and quantum learning methods, decision-making to adapt at one month was considered. The MDP objective was defined by the complication-free tumor control (P{sup +}=TCPx(1-NTCP)). A simple regression model represented state-action mapping. Single bit in classical MDP and a qubit of 2-superimposed states in quantum MDP represented the decision actions. Classical decision selection was done using reinforcement Q-learning and quantum searching was performed using Grover’s algorithm, which applies uniform superposition over possible states and yields quadratic speed-up. Results: Classical/quantum MDPs suggested adaptation (probability amplitude ≥0.5) 79% of the time for splitcourses and 100% for continuous-courses. However, the classical MDP had an average adaptation probability of 0.5±0.22 while the quantum algorithm reached 0.76±0.28. In cases where adaptation failed, classical MDP yielded 0.31±0.26 average amplitude while the

Comprehensive evaluation of ten deformable image registration algorithms for contour propagation between CT and cone-beam CT images in adaptive head & neck radiotherapy.

Directory of Open Access Journals (Sweden)

Xin Li

Full Text Available Deformable image registration (DIR is a critical technic in adaptive radiotherapy (ART for propagating contours between planning computerized tomography (CT images and treatment CT/cone-beam CT (CBCT images to account for organ deformation for treatment re-planning. To validate the ability and accuracy of DIR algorithms in organ at risk (OAR contour mapping, ten intensity-based DIR strategies, which were classified into four categories-optical flow-based, demons-based, level-set-based and spline-based-were tested on planning CT and fractional CBCT images acquired from twenty-one head & neck (H&N cancer patients who underwent 6~7-week intensity-modulated radiation therapy (IMRT. Three similarity metrics, i.e., the Dice similarity coefficient (DSC, the percentage error (PE and the Hausdorff distance (HD, were employed to measure the agreement between the propagated contours and the physician-delineated ground truths of four OARs, including the vertebra (VTB, the vertebral foramen (VF, the parotid gland (PG and the submandibular gland (SMG. It was found that the evaluated DIRs in this work did not necessarily outperform rigid registration. DIR performed better for bony structures than soft-tissue organs, and the DIR performance tended to vary for different ROIs with different degrees of deformation as the treatment proceeded. Generally, the optical flow-based DIR performed best, while the demons-based DIR usually ranked last except for a modified demons-based DISC used for CT-CBCT DIR. These experimental results suggest that the choice of a specific DIR algorithm depends on the image modality, anatomic site, magnitude of deformation and application. Therefore, careful examinations and modifications are required before accepting the auto-propagated contours, especially for automatic re-planning ART systems.

Image-guided radiotherapy quality control: Statistical process control using image similarity metrics.

Science.gov (United States)

Shiraishi, Satomi; Grams, Michael P; Fong de Los Santos, Luis E

2018-05-01

The purpose of this study was to demonstrate an objective quality control framework for the image review process. A total of 927 cone-beam computed tomography (CBCT) registrations were retrospectively analyzed for 33 bilateral head and neck cancer patients who received definitive radiotherapy. Two registration tracking volumes (RTVs) - cervical spine (C-spine) and mandible - were defined, within which a similarity metric was calculated and used as a registration quality tracking metric over the course of treatment. First, sensitivity to large misregistrations was analyzed for normalized cross-correlation (NCC) and mutual information (MI) in the context of statistical analysis. The distribution of metrics was obtained for displacements that varied according to a normal distribution with standard deviation of σ = 2 mm, and the detectability of displacements greater than 5 mm was investigated. Then, similarity metric control charts were created using a statistical process control (SPC) framework to objectively monitor the image registration and review process. Patient-specific control charts were created using NCC values from the first five fractions to set a patient-specific process capability limit. Population control charts were created using the average of the first five NCC values for all patients in the study. For each patient, the similarity metrics were calculated as a function of unidirectional translation, referred to as the effective displacement. Patient-specific action limits corresponding to 5 mm effective displacements were defined. Furthermore, effective displacements of the ten registrations with the lowest similarity metrics were compared with a three dimensional (3DoF) couch displacement required to align the anatomical landmarks. Normalized cross-correlation identified suboptimal registrations more effectively than MI within the framework of SPC. Deviations greater than 5 mm were detected at 2.8σ and 2.1σ from the mean for NCC and MI

Image registration assessment in radiotherapy image guidance based on control chart monitoring.

Science.gov (United States)

Xia, Wenyao; Breen, Stephen L

2018-04-01

Image guidance with cone beam computed tomography in radiotherapy can guarantee the precision and accuracy of patient positioning prior to treatment delivery. During the image guidance process, operators need to take great effort to evaluate the image guidance quality before correcting a patient's position. This work proposes an image registration assessment method based on control chart monitoring to reduce the effort taken by the operator. According to the control chart plotted by daily registration scores of each patient, the proposed method can quickly detect both alignment errors and image quality inconsistency. Therefore, the proposed method can provide a clear guideline for the operators to identify unacceptable image quality and unacceptable image registration with minimal effort. Experimental results demonstrate that by using control charts from a clinical database of 10 patients undergoing prostate radiotherapy, the proposed method can quickly identify out-of-control signals and find special cause of out-of-control registration events.

Quality assurance in MR image guided adaptive brachytherapy for cervical cancer: Final results of the EMBRACE study dummy run

DEFF Research Database (Denmark)

Kirisits, Christian; Federico, Mario; Nkiwane, Karen

2015-01-01

and BT. Centers with experience in IGABT (>30 cases) had better performance as compared to centers with limited experience. CONCLUSION: The comprehensive dummy run designed for the EMBRACE trial has been a feasible tool for QA in IGABT of cervix cancer. It should be considered for future IGABT trials...... aspects of image guided adaptive brachytherapy (IGABT). METHODS AND MATERIALS: EMBRACE is a prospective multicenter trial aiming to assess the impact of (MRI)-based IGABT in locally advanced cervical cancer. An EMBRACE dummy run was designed to identify sources and magnitude of uncertainties and errors...

Image quality and stability of image-guided radiotherapy (IGRT) devices: A comparative study.

Science.gov (United States)

Stock, Markus; Pasler, Marlies; Birkfellner, Wolfgang; Homolka, Peter; Poetter, Richard; Georg, Dietmar

2009-10-01

Our aim was to implement standards for quality assurance of IGRT devices used in our department and to compare their performances with that of a CT simulator. We investigated image quality parameters for three devices over a period of 16months. A multislice CT was used as a benchmark and results related to noise, spatial resolution, low contrast visibility (LCV) and uniformity were compared with a cone beam CT (CBCT) at a linac and simulator. All devices performed well in terms of LCV and, in fact, exceeded vendor specifications. MTF was comparable between CT and linac CBCT. Integral nonuniformity was, on average, 0.002 for the CT and 0.006 for the linac CBCT. Uniformity, LCV and MTF varied depending on the protocols used for the linac CBCT. Contrast-to-noise ratio was an average of 51% higher for the CT than for the linac and simulator CBCT. No significant time trend was observed and tolerance limits were implemented. Reasonable differences in image quality between CT and CBCT were observed. Further research and development are necessary to increase image quality of commercially available CBCT devices in order for them to serve the needs for adaptive and/or online planning.

Magnetic resonance imaging in radiotherapy treatment planning

NARCIS (Netherlands)

Moerland, Marinus Adriaan

1996-01-01

From its inception in the early 1970's up to the present, magnetic resonance imaging (MRI) has evolved into a sophisticated technique, which has aroused considerable interest in var- ious subelds of medicine including radiotherapy. MRI is capable of imaging in any plane and does not use ionizing

A strategy for the use of image-guided radiotherapy (IGRT) on linear accelerators and its impact on treatment margins for prostate cancer patients

International Nuclear Information System (INIS)

Nairz, Olaf; Deutschmann, Heinz; Zehentmayr, Franz; Sedlmayer, Felix; Paracelsus Medical University Salzburg; Merz, Florian; Kopp, Peter; Schoeller, Helmut; Wurstbauer, Karl; Kametriser, Gerhard

2008-01-01

In external beam radiotherapy of prostate cancer, the consideration of various systematic error types leads to wide treatment margins compromising normal tissue tolerance. We investigated if systematic set-up errors can be reduced by a set of initial image-guided radiotherapy (IGRT) sessions. 27 patients received daily IGRT resulting in a set of 882 cone-beam computed tomographies (CBCTs). After matching to bony structures, we analyzed the dimensions of remaining systematic errors from zero up to six initial IGRT sessions and aimed at a restriction of daily IGRT for 10% of all patients. For threshold definition, we determined the standard deviations (SD) of the shift corrections and selected patients out of this range for daily image guidance. To calculate total treatment margins, we demanded for a cumulative clinical target volume (CTV) coverage of at least 95% of the specified dose in 90% of all patients. The gain of accuracy was largest during the first three IGRTs. In order to match precision and workload criteria, thresholds for the SD of the corrections of 3.5 mm, 2.0 mm and 4.5 mm in the left-right (L-R), cranial-caudal (C-C), and anterior-posterior (A-P) direction, respectively, were identified. Including all other error types, the total margins added to the CTV amounted to 8.6 mm in L-R, 10.4 mm in C-C, and 14.4 mm in A-P direction. Only initially performed IGRT might be helpful for eliminating gross systematic errors especially after virtual simulation. However, even with daily IGRT performance, a substantial PTV margin reduction is only achievable by matching internal markers instead of bony anatomical structures. (orig.)

MO-E-BRC-02: MRI-Guided Online Adaptive Radiotherapy: The UCLA Approach to Quality Management

Energy Technology Data Exchange (ETDEWEB)

Lamb, J. [University of California, Los Angeles (United States)

2016-06-15

Online adaptive radiation therapy has the potential to ensure delivery of optimal treatment to the patient by accounting for anatomical and potentially functional changes that occur from one fraction to the next and over the course of treatment. While on-line adaptive RT (ART) has been a topic of many publications, discussions, and research, it has until very recently remained largely a concept and not a practical implementation. However, recent advances in on-table imaging, use of deformable image registration for contour generation and dose tracking, faster and more efficient plan optimization, as well as fast quality assurance method has enabled the implementation of ART in the clinic in the past couple of years. The introduction of these tools into routine clinical use requires many considerations and progressive knowledge to understand how processes that have historically taken hours/days to complete can now be done in less than 30 minutes. This session will discuss considerations to perform real time contouring, planning and patient specific QA, as well as a practical workflow and the required resources. Learning Objectives: To understand the difficulties, challenges and available technologies for online adaptive RT. To understand how to implement online adaptive therapy in a clinical environment and to understand the workflow and resources required. To understand the limitations and sources of uncertainty in the online adaptive process I have research funding from ViewRay Inc. and Philips Medical Systems.; R. Kashani, I have research funding from ViewRay Inc. and Philips Medical Systems.; X. Li, Research supported by Elekta Inc.

MO-E-BRC-02: MRI-Guided Online Adaptive Radiotherapy: The UCLA Approach to Quality Management

International Nuclear Information System (INIS)

Lamb, J.

2016-01-01

Online adaptive radiation therapy has the potential to ensure delivery of optimal treatment to the patient by accounting for anatomical and potentially functional changes that occur from one fraction to the next and over the course of treatment. While on-line adaptive RT (ART) has been a topic of many publications, discussions, and research, it has until very recently remained largely a concept and not a practical implementation. However, recent advances in on-table imaging, use of deformable image registration for contour generation and dose tracking, faster and more efficient plan optimization, as well as fast quality assurance method has enabled the implementation of ART in the clinic in the past couple of years. The introduction of these tools into routine clinical use requires many considerations and progressive knowledge to understand how processes that have historically taken hours/days to complete can now be done in less than 30 minutes. This session will discuss considerations to perform real time contouring, planning and patient specific QA, as well as a practical workflow and the required resources. Learning Objectives: To understand the difficulties, challenges and available technologies for online adaptive RT. To understand how to implement online adaptive therapy in a clinical environment and to understand the workflow and resources required. To understand the limitations and sources of uncertainty in the online adaptive process I have research funding from ViewRay Inc. and Philips Medical Systems.; R. Kashani, I have research funding from ViewRay Inc. and Philips Medical Systems.; X. Li, Research supported by Elekta Inc.

Long-term outcomes from dose-escalated image-guided intensity-modulated radiotherapy with androgen deprivation: encouraging results for intermediate- and high-risk prostate cancer.

Science.gov (United States)

Wilcox, Shea W; Aherne, Noel J; Benjamin, Linus C; Wu, Bosco; de Campos Silva, Thomaz; McLachlan, Craig S; McKay, Michael J; Last, Andrew J; Shakespeare, Thomas P

2014-01-01

Dose-escalated (DE) radiotherapy in the setting of localized prostate cancer has been shown to improve biochemical disease-free survival (bDFS) in several studies. In the same group of patients, androgen deprivation therapy (ADT) has been shown to confer a survival benefit when combined with radiotherapy doses of up to 70 Gy; however, there is currently little long-term data on patients who have received high-dose intensity-modulated radiotherapy (IMRT) with ADT. We report the long-term outcomes in a large cohort of patients treated with the combination of DE image-guided IMRT (IG-IMRT) and ADT. Patients with localized prostate cancer were identified from a centralized database across an integrated cancer center. All patients received DE IG-IMRT, combined with ADT, and had a minimum follow up of 12 months post-radiotherapy. All relapse and toxicity data were collected prospectively. Actuarial bDFS, metastasis-free survival, prostate cancer-specific survival, and multivariate analyses were calculated using the SPSS v20.0 statistical package. Seven hundred and eighty-two eligible patients were identified with a median follow up of 46 months. Overall, 4.3% of patients relapsed, 2.0% developed distant metastases, and 0.6% died from metastatic prostate cancer. At 5-years, bDFS was 88%, metastasis-free survival was 95%, and prostate cancer-specific survival was 98%. Five-year grade 2 genitourinary and gastrointestinal toxicity was 2.1% and 3.4%, respectively. No grade 3 or 4 late toxicities were reported. Pretreatment prostate specific antigen (P=0.001) and Gleason score (P=0.03) were significant in predicting biochemical failure on multivariate analysis. There is a high probability of tumor control with DE IG-IMRT combined with androgen deprivation, and this is a technique with a low probability of significant late toxicity. Our long term results corroborate the safety and efficacy of treating with IG-IMRT to high doses and compares favorably with published series for

An integrated multimodality image-guided robot system for small-animal imaging research

International Nuclear Information System (INIS)

Hsu, Wen-Lin; Hsin Wu, Tung; Hsu, Shih-Ming; Chen, Chia-Lin; Lee, Jason J.S.; Huang, Yung-Hui

2011-01-01

We design and construct an image-guided robot system for use in small-animal imaging research. This device allows the use of co-registered small-animal PET-MRI images to guide the movements of robotic controllers, which will accurately place a needle probe at any predetermined location inside, for example, a mouse tumor, for biological readouts without sacrificing the animal. This system is composed of three major components: an automated robot device, a CCD monitoring mechanism, and a multimodality registration implementation. Specifically, the CCD monitoring mechanism was used for correction and validation of the robot device. To demonstrate the value of the proposed system, we performed a tumor hypoxia study that involved FMISO small-animal PET imaging and the delivering of a pO 2 probe into the mouse tumor using the image-guided robot system. During our evaluation, the needle positioning error was found to be within 0.153±0.042 mm of desired placement; the phantom simulation errors were within 0.693±0.128 mm. In small-animal studies, the pO 2 probe measurements in the corresponding hypoxia areas showed good correlation with significant, low tissue oxygen tensions (less than 6 mmHg). We have confirmed the feasibility of the system and successfully applied it to small-animal investigations. The system could be easily adapted to extend to other biomedical investigations in the future.

Image and laparoscopic guided interstitial brachytherapy for locally advanced primary or recurrent gynaecological cancer using the adaptive GEC ESTRO target concept

International Nuclear Information System (INIS)

Fokdal, Lars; Tanderup, Kari; Nielsen, Soren Kynde; Christensen, Henrik Kidmose; Rohl, Lisbeth; Pedersen, Erik Morre; Schonemann, Niels Kim; Lindegaard, Jacob Christian

2011-01-01

Purpose: To retrospectively assess treatment outcome of image and laparoscopic guided interstitial pulsed dose rate brachytherapy (PDR-BT) for locally advanced gynaecological cancer using the adaptive GEC ESTRO target concept. Materials and methods: Between June 2005 and December 2010, 28 consecutive patients were treated for locally advanced primary vaginal (nine), recurrent endometrial (12) or recurrent cervical cancer (seven) with combined external beam radiotherapy (EBRT) and interstitial PDR-BT. Treatment was initiated with whole pelvic EBRT to a median dose of 45 Gy followed by PDR-BT using the Martinez Universal Perineal Interstitial Template (MUPIT). All implants were virtually preplanned using MRI of the pelvis with a dummy MUPIT in situ. The GEC ESTRO high risk clinical target volume (HR CTV), intermediate risk clinical target volume (IR CTV) and the organs at risk (OAR) were contoured and a preplan for implantation was generated (BrachyVision, Varian). The subsequent implantation was performed under laparoscopic visualisation. Final contouring and treatment planning were done using a post-implant CT. Planning aim of PDR-BT was to deliver 30 Gy in 50 hourly pulses to HR CTV. Manual dose optimisation was performed with the aim of reaching a D90 > 80 Gy in the HR CTV calculated as the total biologically equivalent to 2 Gy fractions of EBRT and BT (EQD2). Dose to the OAR were evaluated using dose volume constraints for D 2cc of 90 Gy for bladder and 70 Gy for rectum and sigmoid. Results: For HR CTV the median volume was 26 cm 3 (7-91 cm 3 ). Coverage of the HR CTV was 97% (90-100%) and D90 was 82 Gy (77-88 Gy). The D 2cc for bladder, rectum, and sigmoid were 65 Gy (47-81 Gy), 61 Gy (50-77 Gy), and 52 Gy (44-68 Gy), respectively. Median follow up was 18 months (6-61 months). The actuarial 2 years local control rate was 92% (SE 5), while disease-free survival and overall survival were 59% (SE 11) and 74%, respectively (SE 10). No complications to the

Realization of 3D evaluation algorithm in dose-guided radiotherapy

International Nuclear Information System (INIS)

Wang Yu; Li Gui; Wang Dong; Wu Yican; FDS Team

2012-01-01

3D evaluation algorithm instead of 2D evaluation method of clinical dose verification is highly needed for dose evaluation in Dose-guided Radiotherapy. 3D evaluation algorithm of three evaluation methods, including Dose Difference, Distance-To-Agreement and 7 Analysis, was realized by the tool of Visual C++ according to the formula. Two plans were designed to test the algorithm, plan 1 was radiation on equivalent water using square field for the verification of the algorithm's correctness; plan 2 was radiation on the emulation head phantom using conformal field for the verification of the algorithm's practicality. For plan 1, the dose difference, in the tolerance range has a pass rate of 100%, the Distance-To-Agreement and 7 analysis was of a pass rate of 100% in the tolerance range, and a pass rate of 99±1% at the boundary of range. For plan 2, the pass rate of algorithm were 88.35%, 100%, 95.07% for the three evaluation methods, respectively. It can be concluded that the 3D evaluation algorithm is feasible and could be used to evaluate 3D dose distributions in Dose-guided Radiotherapy. (authors)

Implementation of single-breath-hold cone beam CT guided hypofraction radiotherapy for lung cancer

International Nuclear Information System (INIS)

Zhong, Renming; Lu, You; Wang, Jin; Zhou, Lin; Xu, Feng; Liu, Li; Zhou, Jidan; Jiang, Xiaoqin; Chen, Nianyong; Bai, Sen

2014-01-01

To analyze the feasibility of active breath control (ABC), the lung tumor reproducibility and the rationale for single-breath-hold cone beam CT (CBCT)-guided hypofraction radiotherapy. Single-breath-hold CBCT images were acquired using ABC in a cohort of 83 lung cancer patients (95 tumors) treated with hypofraction radiotherapy. For all alignments between the reference CT and CBCT images (including the pre-correction, post-correction and post-treatment CBCT images), the tumor reproducibility was evaluated via online manual alignment of the tumors, and the vertebral bone uncertainties were evaluated via offline manual alignment of the vertebral bones. The difference between the tumor reproducibility and the vertebral bone uncertainty represents the change in the tumor position relative to the vertebral bone. The relative tumor positions along the coronal, sagittal and transverse axes were measured based on the reference CT image. The correlations between the vertebral bone uncertainty, the relative tumor position, the total treatment time and the tumor reproducibility were evaluated using the Pearson correlations. Pre-correction, the systematic/random errors of tumor reproducibility were 4.5/2.6 (medial-lateral, ML), 5.1/4.8 (cranial-caudal, CC) and 4.0/3.6 mm (anterior-posterior, AP). These errors were significantly decreased to within 3 mm, both post-correction and post-treatment. The corresponding PTV margins were 4.7 (ML), 7.4 (CC) and 5.4 (AP) mm. The changes in the tumor position relative to the vertebral bone displayed systematic/random errors of 2.2/2.0 (ML), 4.1/4.4 (CC) and 3.1/3.3 (AP) mm. The uncertainty of the vertebral bone significantly correlated to the reproducibility of the tumor position (P < 0.05), except in the CC direction post-treatment. However, no significant correlation was detected between the relative tumor position, the total treatment time and the tumor reproducibility (P > 0.05). Using ABC for single-breath-hold CBCT guidance is an

Actual Dose Variation of Parotid Glands and Spinal Cord for Nasopharyngeal Cancer Patients During Radiotherapy

International Nuclear Information System (INIS)

Han Chunhui; Chen Yijen; Liu An; Schultheiss, Timothy E.; Wong, Jeffrey Y.C.

2008-01-01

Purpose: For intensity-modulated radiotherapy of nasopharyngeal cancer, accurate dose delivery is crucial to the success of treatment. This study aimed to evaluate the significance of daily image-guided patient setup corrections and to quantify the parotid gland volume and dose variations for nasopharyngeal cancer patients using helical tomotherapy megavoltage computed tomography (CT). Methods and Materials: Five nasopharyngeal cancer patients who underwent helical tomotherapy were selected retrospectively. Each patient had received 70 Gy in 35 fractions. Daily megavoltage CT scans were registered with the planning CT images to correct the patient setup errors. Contours of the spinal cord and parotid glands were drawn on the megavoltage CT images at fixed treatment intervals. The actual doses delivered to the critical structures were calculated using the helical tomotherapy Planned Adaptive application. Results: The maximal dose to the spinal cord showed a significant increase and greater variation without daily setup corrections. The significant decrease in the parotid gland volume led to a greater median dose in the later phase of treatment. The average parotid gland volume had decreased from 20.5 to 13.2 cm 3 by the end of treatment. On average, the median dose to the parotid glands was 83 cGy and 145 cGy for the first and the last treatment fractions, respectively. Conclusions: Daily image-guided setup corrections can eliminate significant dose variations to critical structures. Constant monitoring of patient anatomic changes and selective replanning should be used during radiotherapy to avoid critical structure complications

Intrafractional prostate motion during online image guided intensity-modulated radiotherapy for prostate cancer

International Nuclear Information System (INIS)

Budiharto, Tom; Slagmolen, Pieter; Haustermans, Karin; Maes, Frederik; Junius, Sara; Verstraete, Jan; Oyen, Raymond; Hermans, Jeroen; Van den Heuvel, Frank

2011-01-01

Introduction: Intrafractional motion consists of two components: (1) the movement between the on-line repositioning procedure and the treatment start and (2) the movement during the treatment delivery. The goal of this study is to estimate this intrafractional movement of the prostate during prostate cancer radiotherapy. Material and methods: Twenty-seven patients with prostate cancer and implanted fiducials underwent a marker match procedure before a five-field IMRT treatment. For all fields, in-treatment images were obtained and then processed to enable automatic marker detection. Combining the subsequent projection images, five positions of each marker were determined using the shortest path approach. The residual set-up error (RSE) after kV-MV based prostate localization, the prostate position as a function of time during a radiotherapy session and the required margins to account for intrafractional motion were determined. Results: The mean RSE and standard deviation in the antero-posterior, cranio-caudal and left-right direction were 2.3 ± 1.5 mm, 0.2 ± 1.1 mm and -0.1 ± 1.1 mm, respectively. Almost all motions occurred in the posterior direction before the first treatment beam as the percentage of excursions >5 mm was reduced significantly when the RSE was not accounted for. The required margins for intrafractional motion increased with prolongation of the treatment. Application of a repositioning protocol after every beam could decrease the 1 cm margin from CTV to PTV by 2 mm. Conclusions: The RSE is the main contributor to intrafractional motion. This RSE after on-line prostate localization and patient repositioning in the posterior direction emphasizes the need to speed up the marker match procedure. Also, a prostate IMRT treatment should be administered as fast as possible, to ensure that the pre-treatment repositioning efforts are not erased by intrafractional prostate motion. This warrants an optimized workflow with the use of faster treatment

Measurement of cone beam CT coincidence with megavoltage isocentre and image sharpness using the QUASAR(TM) Penta-Guide phantom

International Nuclear Information System (INIS)

Sykes, J R; Lindsay, R; Dean, C J; Thwaites, D I; Brettle, D S; Magee, D R

2008-01-01

For image-guided radiotherapy (IGRT) systems based on cone beam CT (CBCT) integrated into a linear accelerator, the reproducible alignment of imager to x-ray source is critical to the registration of both the x-ray-volumetric image with the megavoltage (MV) beam isocentre and image sharpness. An enhanced method of determining the CBCT to MV isocentre alignment using the QUASAR(TM) Penta-Guide phantom was developed which improved both precision and accuracy. This was benchmarked against our existing method which used software and a ball-bearing (BB) phantom provided by Elekta. Additionally, a method of measuring an image sharpness metric (MTF 50 ) from the edge response function of a spherical air cavity within the Penta-Guide phantom was developed and its sensitivity was tested by simulating misalignments of the kV imager. Reproducibility testing of the enhanced Penta-Guide method demonstrated a systematic error of 50 for five measurements was 0.278 ± 0.004 lp mm -1 with no applied misalignment. Simulated misalignments exhibited a clear peak in the MTF 50 enabling misalignments greater than 0.4 mm to be detected. The Penta-Guide phantom can be used to precisely measure CBCT-MV coincidence and image sharpness on CBCT-IGRT systems

The future of personalised radiotherapy for head and neck cancer.

Science.gov (United States)

Caudell, Jimmy J; Torres-Roca, Javier F; Gillies, Robert J; Enderling, Heiko; Kim, Sungjune; Rishi, Anupam; Moros, Eduardo G; Harrison, Louis B

2017-05-01

Radiotherapy has long been the mainstay of treatment for patients with head and neck cancer and has traditionally involved a stage-dependent strategy whereby all patients with the same TNM stage receive the same therapy. We believe there is a substantial opportunity to improve radiotherapy delivery beyond just technological and anatomical precision. In this Series paper, we explore several new ideas that could improve understanding of the phenotypic and genotypic differences that exist between patients and their tumours. We discuss how exploiting these differences and taking advantage of precision medicine tools-such as genomics, radiomics, and mathematical modelling-could open new doors to personalised radiotherapy adaptation and treatment. We propose a new treatment shift that moves away from an era of empirical dosing and fractionation to an era focused on the development of evidence to guide personalisation and biological adaptation of radiotherapy. We believe these approaches offer the potential to improve outcomes and reduce toxicity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Image quality and stability of image-guided radiotherapy (IGRT) devices: A comparative study

International Nuclear Information System (INIS)

Stock, Markus; Pasler, Marlies; Birkfellner, Wolfgang; Homolka, Peter; Poetter, Richard; Georg, Dietmar

2009-01-01

Introduction: Our aim was to implement standards for quality assurance of IGRT devices used in our department and to compare their performances with that of a CT simulator. Materials and methods: We investigated image quality parameters for three devices over a period of 16 months. A multislice CT was used as a benchmark and results related to noise, spatial resolution, low contrast visibility (LCV) and uniformity were compared with a cone beam CT (CBCT) at a linac and simulator. Results: All devices performed well in terms of LCV and, in fact, exceeded vendor specifications. MTF was comparable between CT and linac CBCT. Integral nonuniformity was, on average, 0.002 for the CT and 0.006 for the linac CBCT. Uniformity, LCV and MTF varied depending on the protocols used for the linac CBCT. Contrast-to-noise ratio was an average of 51% higher for the CT than for the linac and simulator CBCT. No significant time trend was observed and tolerance limits were implemented. Discussion: Reasonable differences in image quality between CT and CBCT were observed. Further research and development are necessary to increase image quality of commercially available CBCT devices in order for them to serve the needs for adaptive and/or online planning.

Imaging and dosimetric errors in 4D PET/CT-guided radiotherapy from patient-specific respiratory patterns: a dynamic motion phantom end-to-end study

International Nuclear Information System (INIS)

Bowen, S R; Nyflot, M J; Meyer, J; Sandison, G A; Herrmann, C; Groh, C M; Wollenweber, S D; Stearns, C W; Kinahan, P E

2015-01-01

planning, and RT delivery under a dose painting paradigm is feasible within an integrated respiratory motion phantom workflow. For a limited set of cases, the magnitude of errors was comparable during PET/CT imaging and treatment delivery without motion compensation. Errors were moderately mitigated during PET/CT imaging and significantly mitigated during RT delivery with motion compensation. This dynamic motion phantom end-to-end workflow provides a method for quality assurance of 4D PET/CT-guided radiotherapy, including evaluation of respiratory motion compensation methods during imaging and treatment delivery. (paper)

Imaging and dosimetric errors in 4D PET/CT-guided radiotherapy from patient-specific respiratory patterns: a dynamic motion phantom end-to-end study

Science.gov (United States)

Bowen, S R; Nyflot, M J; Hermann, C; Groh, C; Meyer, J; Wollenweber, S D; Stearns, C W; Kinahan, P E; Sandison, G A

2015-01-01

magnitude of errors was comparable during PET/CT imaging and treatment delivery without motion compensation. Errors were moderately mitigated during PET/CT imaging and significantly mitigated during RT delivery with motion compensation. This dynamic motion phantom end-to-end workflow provides a method for quality assurance of 4D PET/CT-guided radiotherapy, including evaluation of respiratory motion compensation methods during imaging and treatment delivery. PMID:25884892

Long-term follow-up after modern radical prostate cancer radiotherapy

DEFF Research Database (Denmark)

Sander, Lotte

that clinical target volumes are up to 30% smaller on MRI delineation compared to computer tomography delineation. The overall aim of the thesis was to explore the use of MRI target planning and a Nicle-Titanium prostate stent as fiducial marker for both MR-CT co-registration and image guided radiotherapy....... radiotherapy is a well established treatment modality for prostate cancer. Accuracy and precision are key words with regard to optimal survival and minimal toxicity in modern radiotherapy and are fundamentals in modern radiotherapy. Modern imaging has improved the ability to define radiotherapy target volumes......A significant increase in the prostate cancer incidence has made prostate cancer a major health problem in recent years. Because of the often but unfortunately not always indolent nature of the disease, over-diagnosis and over-treatment are relevant clinical and ethic dilemmas. External beam...

SU-D-207A-04: Use of Gradient Echo Plural Contrast Imaging (GEPCI) in MR-Guided Radiation Therapy: A Feasibility Study Targeting Brain Treatment

International Nuclear Information System (INIS)

Cai, B; Rao, Y; Tsien, C; Huang, J; Green, O; Mutic, S; Gach, H; Wen, J; Yablonskiy, D

2016-01-01

Purpose: To implement the Gradient Echo Plural Contrast Imaging(GEPCI) technique in MRI-simulation for radiation therapy and assess the feasibility of using GEPCI images with advanced inhomogeneity correction in MRI-guided radiotherapy for brain treatment. Methods: An optimized multigradient-echo GRE sequence (TR=50ms;TE1=4ms;delta-TE=4ms;flip angle=300,11 Echoes) was developed to generate both structural (T1w and T2*w) and functional MRIs (field and susceptibility maps) from a single acquisition. One healthy subject (Subject1) and one post-surgical brain cancer patient (Subject2) were scanned on a Philips Ingenia 1.5T MRI used for radiation therapy simulation. Another healthy subject (Subject3) was scanned on a 0.35T MRI-guided radiotherapy (MR-IGRT) system (ViewRay). A voxel spread function (VSF) was used to correct the B0 inhomogeneities caused by surgical cavities and edema for Subject2. GEPCI images and standard radiotherapy planning MRIs for this patient were compared focusing the delineation of radiotherapy target region. Results: GEPCI brain images were successfully derived from all three subjects with scan times of <7 minutes. The images derived for Subjects1&2 demonstrated that GEPCI can be applied and combined into radiotherapy MRI simulation. Despite low field, T1-weighted and R2* images were successfully reconstructed for Subject3 and were satisfactory for contour and target delineation. The R2* distribution of grey matter (center=12,FWHM=4.5) and white matter (center=14.6, FWHM=2) demonstrated the feasibility for tissue segmentation and quantification. The voxel spread function(VSF) corrected surgical site related inhomogeneities for Subject2. R2* and quantitative susceptibility map(QSM) images for Subject2 can be used to quantitatively assess the brain structure response to radiation over the treatment course. Conclusion: We implemented the GEPCI technique in MRI-simulation and in MR-IGRT system for radiation therapy. The images demonstrated that it

Measurement of cone beam CT coincidence with megavoltage isocentre and image sharpness using the QUASAR Penta-Guide phantom.

Science.gov (United States)

Sykes, J R; Lindsay, R; Dean, C J; Brettle, D S; Magee, D R; Thwaites, D I

2008-10-07

For image-guided radiotherapy (IGRT) systems based on cone beam CT (CBCT) integrated into a linear accelerator, the reproducible alignment of imager to x-ray source is critical to the registration of both the x-ray-volumetric image with the megavoltage (MV) beam isocentre and image sharpness. An enhanced method of determining the CBCT to MV isocentre alignment using the QUASAR Penta-Guide phantom was developed which improved both precision and accuracy. This was benchmarked against our existing method which used software and a ball-bearing (BB) phantom provided by Elekta. Additionally, a method of measuring an image sharpness metric (MTF(50)) from the edge response function of a spherical air cavity within the Penta-Guide phantom was developed and its sensitivity was tested by simulating misalignments of the kV imager. Reproducibility testing of the enhanced Penta-Guide method demonstrated a systematic error of <0.2 mm when compared to the BB method with near equivalent random error (s=0.15 mm). The mean MTF(50) for five measurements was 0.278+/-0.004 lp mm(-1) with no applied misalignment. Simulated misalignments exhibited a clear peak in the MTF(50) enabling misalignments greater than 0.4 mm to be detected. The Penta-Guide phantom can be used to precisely measure CBCT-MV coincidence and image sharpness on CBCT-IGRT systems.

Guided SAR image despeckling with probabilistic non local weights

Science.gov (United States)

Gokul, Jithin; Nair, Madhu S.; Rajan, Jeny

2017-12-01

SAR images are generally corrupted by granular disturbances called speckle, which makes visual analysis and detail extraction a difficult task. Non Local despeckling techniques with probabilistic similarity has been a recent trend in SAR despeckling. To achieve effective speckle suppression without compromising detail preservation, we propose an improvement for the existing Generalized Guided Filter with Bayesian Non-Local Means (GGF-BNLM) method. The proposed method (Guided SAR Image Despeckling with Probabilistic Non Local Weights) replaces parametric constants based on heuristics in GGF-BNLM method with dynamically derived values based on the image statistics for weight computation. Proposed changes make GGF-BNLM method adaptive and as a result, significant improvement is achieved in terms of performance. Experimental analysis on SAR images shows excellent speckle reduction without compromising feature preservation when compared to GGF-BNLM method. Results are also compared with other state-of-the-art and classic SAR depseckling techniques to demonstrate the effectiveness of the proposed method.

Adaptive radiotherapy for long course neo-adjuvant treatment of rectal cancer

International Nuclear Information System (INIS)

Nijkamp, Jasper; Marijnen, Corrie; Herk, Marcel van; Triest, Baukelien van; Sonke, Jan-Jakob

2012-01-01

Purpose: To quantify the potential margin reduction with adaptive radiotherapy (ART) during neo-adjuvant treatment of locally-advanced rectal cancer. Methods and materials: Repeat CT scans were acquired for 28 patients treated with 25 × 2 Gy, daily during the first week, and followed by weekly scans. The CTV was delineated on all scans, and shape variation was estimated. Five ART strategies were tested, consisting of an average CTV over the planning CT and one to five repeat CTs. Required PTV margins were calculated for adapted and non-adapted treatment. The strategy with the least PTV volume over the whole treatment was selected and bowel area dose reduction was estimated. Results: Substantial systematic and random shape variation demanded for a PTV margin up to 2.4 cm at the upper-anterior part of the CTV. Plan adaptation after fraction 4 resulted in a maximum 0.7 cm margin reduction and a significant PTV reduction from 1185 to 1023 cc (p < 0.0001). The bowel area volume receiving 15, 45, and 50 Gy was reduced from 436 to 402 cc, 111 to 81 cc, and 49 to 29 cc, respectively (p < 0.0001). Conclusions: With adaptive radiotherapy, maximum required PTV margins can be reduced from 2.4 to 1.7 cm, resulting in significantly less dose to the bowel area.

Real-time 3D-surface-guided head refixation useful for fractionated stereotactic radiotherapy

International Nuclear Information System (INIS)

Li Shidong; Liu Dezhi; Yin Gongjie; Zhuang Ping; Geng, Jason

2006-01-01

Accurate and precise head refixation in fractionated stereotactic radiotherapy has been achieved through alignment of real-time 3D-surface images with a reference surface image. The reference surface image is either a 3D optical surface image taken at simulation with the desired treatment position, or a CT/MRI-surface rendering in the treatment plan with corrections for patient motion during CT/MRI scans and partial volume effects. The real-time 3D surface images are rapidly captured by using a 3D video camera mounted on the ceiling of the treatment vault. Any facial expression such as mouth opening that affects surface shape and location can be avoided using a new facial monitoring technique. The image artifacts on the real-time surface can generally be removed by setting a threshold of jumps at the neighboring points while preserving detailed features of the surface of interest. Such a real-time surface image, registered in the treatment machine coordinate system, provides a reliable representation of the patient head position during the treatment. A fast automatic alignment between the real-time surface and the reference surface using a modified iterative-closest-point method leads to an efficient and robust surface-guided target refixation. Experimental and clinical results demonstrate the excellent efficacy of <2 min set-up time, the desired accuracy and precision of <1 mm in isocenter shifts, and <1 deg. in rotation

Novel multimodality segmentation using level sets and Jensen-Renyi divergence

NARCIS (Netherlands)

Markel, Daniel; Zaidi, Habib; El Naqa, Issam

2013-01-01

Purpose: Positron emission tomography (PET) is playing an increasing role in radiotherapy treatment planning. However, despite progress, robust algorithms for PET and multimodal image segmentation are still lacking, especially if the algorithm were extended to image-guided and adaptive radiotherapy

Processing and evaluation of image matching tools in radiotherapy; Mise en oeuvre et evaluation d'outils de fusion d'image en radiotherapie

Energy Technology Data Exchange (ETDEWEB)

Bondiau, P Y

2004-11-15

Cancer is a major problem of public health. Treatment can be done in a general or loco-regional way, in this last case medical images are important as they specify the localization of the tumour. The objective of the radiotherapy is to deliver a curative dose of radiation in the target volume while sparing the organs at risks (O.A.R.). The determination of the accurate localization of the targets volume as well as O.A.R. make it possible to define the ballistic of irradiation beams. After the description of the principles of radiotherapy and cancers treatment, we specify the clinical stakes of ocular, cerebral and prostatic tumours. We present a state of the art of image matching, the various techniques reviewed with an aim of being didactic with respect to the medical community. The results of matching are presented within the framework of the planning of the cerebral and prostatic radiotherapy in order to specify the types of applicable matching in oncology and more particularly in radiotherapy. Then, we present the prospects for this type of application according to various anatomical areas. Applications of automatic segmentation and the evaluation of the results in the framework of brain tumour are described after a review of the various segmentation methods according to anatomical localizations. We will see an original application: the digital simulation of the virtual tumoral growth and the comparison with the real growth of a cerebral tumour presented by a patient. Lastly, we will expose the future developments possible of the tools for image processing in radiotherapy as well as the tracks of research to be explored in oncology. (author)

TU-AB-BRA-07: Distortion-Free 3D Diffusion MRI On An MRI-Guided Radiotherapy System for Longitudinal Tumor Response Assessment

International Nuclear Information System (INIS)

Gao, Y; Yang, Y; Rangwala, N; Cao, M; Low, D; Hu, P

2016-01-01

Purpose: To develop a reliable, 3D distortion-free diffusion MRI technique for longitudinal tumor response assessment and MRI-guided adaptive radiotherapy(RT). Methods: A diffusion prepared 3D turbo spin echo readout (DP-TSE) sequence was developed and compared with the conventional diffusion-weighted single-shot echo-planar-imaging (DW-ssEPI) sequence in a commercially available diffusion phantom, and one head-and-neck and one brain cancer patient on an MRI-guided RT system (ViewRay). In phantom study, the geometric fidelity was quantified as the ratio between the left-right (RL) and anterior-posterior (AP) dimension. Ten slices were measured on DP-TSE, DW-ssEPI and standard TSE images where the later was used as the geometric reference. ADC accuracy was verified at both 0°C (reference ADC available) and room temperature with a range of diffusivity between 0.35 and 2.0*10"−"3mm"2/s. The ADC reproducibility was assessed based on 8 room-temperature measurements on 6 different days. In the pilot single-slice in-vivo study, CT images were used as the geometric reference, and ADC maps from both diffusion sequences were compared. Results: Distortion and susceptive-related artifact were severe in DW-ssEPI, with significantly lower RL/AP ratio (0.9579±0.0163) than DP-TSE (0.9990±0.0031) and TSE (0.9995±0.0031). ADCs from the two diffusion sequences both matched well with the vendor-provided values at 0°C; however DW-ssEPI fails to provide accurate ADC for high diffusivity vials at room temperature due to high noise level (10 times higher than DP-TSE). The DP-TSE sequence had excellent ADC reproducibility with <4% ADC variation among 8 separate measurements. In patient study, DP-TSE exhibited substantially improved geometric reliability. ROI analysis in ADC maps generated from DP-TSE and DW-ssEPI showed <5% difference where high b-value images were excluded from the latter approach due to excessive noise level. Conclusion: A diffusion MRI sequence with excellent

TU-AB-BRA-07: Distortion-Free 3D Diffusion MRI On An MRI-Guided Radiotherapy System for Longitudinal Tumor Response Assessment

Energy Technology Data Exchange (ETDEWEB)

Gao, Y; Yang, Y; Rangwala, N; Cao, M; Low, D; Hu, P [UCLA School of Medicine, Los Angeles, CA (United States)

2016-06-15

Purpose: To develop a reliable, 3D distortion-free diffusion MRI technique for longitudinal tumor response assessment and MRI-guided adaptive radiotherapy(RT). Methods: A diffusion prepared 3D turbo spin echo readout (DP-TSE) sequence was developed and compared with the conventional diffusion-weighted single-shot echo-planar-imaging (DW-ssEPI) sequence in a commercially available diffusion phantom, and one head-and-neck and one brain cancer patient on an MRI-guided RT system (ViewRay). In phantom study, the geometric fidelity was quantified as the ratio between the left-right (RL) and anterior-posterior (AP) dimension. Ten slices were measured on DP-TSE, DW-ssEPI and standard TSE images where the later was used as the geometric reference. ADC accuracy was verified at both 0°C (reference ADC available) and room temperature with a range of diffusivity between 0.35 and 2.0*10{sup −3}mm{sup 2}/s. The ADC reproducibility was assessed based on 8 room-temperature measurements on 6 different days. In the pilot single-slice in-vivo study, CT images were used as the geometric reference, and ADC maps from both diffusion sequences were compared. Results: Distortion and susceptive-related artifact were severe in DW-ssEPI, with significantly lower RL/AP ratio (0.9579±0.0163) than DP-TSE (0.9990±0.0031) and TSE (0.9995±0.0031). ADCs from the two diffusion sequences both matched well with the vendor-provided values at 0°C; however DW-ssEPI fails to provide accurate ADC for high diffusivity vials at room temperature due to high noise level (10 times higher than DP-TSE). The DP-TSE sequence had excellent ADC reproducibility with <4% ADC variation among 8 separate measurements. In patient study, DP-TSE exhibited substantially improved geometric reliability. ROI analysis in ADC maps generated from DP-TSE and DW-ssEPI showed <5% difference where high b-value images were excluded from the latter approach due to excessive noise level. Conclusion: A diffusion MRI sequence with

Compact instrument for fluorescence image-guided surgery

Science.gov (United States)

Wang, Xinghua; Bhaumik, Srabani; Li, Qing; Staudinger, V. Paul; Yazdanfar, Siavash

2010-03-01

Fluorescence image-guided surgery (FIGS) is an emerging technique in oncology, neurology, and cardiology. To adapt intraoperative imaging for various surgical applications, increasingly flexible and compact FIGS instruments are necessary. We present a compact, portable FIGS system and demonstrate its use in cardiovascular mapping in a preclinical model of myocardial ischemia. Our system uses fiber optic delivery of laser diode excitation, custom optics with high collection efficiency, and compact consumer-grade cameras as a low-cost and compact alternative to open surgical FIGS systems. Dramatic size and weight reduction increases flexibility and access, and allows for handheld use or unobtrusive positioning over the surgical field.

Concurrent image-guided intensity modulated radiotherapy and chemotherapy following neoadjuvant chemotherapy for locally advanced nasopharyngeal carcinoma

International Nuclear Information System (INIS)

Shueng, Pei-Wei; Hsieh, Chen-Hsi; Shen, Bing-Jie; Wu, Le-Jung; Liao, Li-Jen; Hsiao, Chi-Huang; Lin, Yu-Chin; Cheng, Po-Wen; Lo, Wu-Chia; Jen, Yee-Min

2011-01-01

To evaluate the experience of induction chemotherapy followed by concurrent chemoradiationwith helical tomotherapy (HT) for nasopharyngeal carcinoma (NPC). Between August 2006 and December 2009, 28 patients with pathological proven nonmetastatic NPC were enrolled. All patients were staged as IIB-IVB. Patients were first treated with 2 to 3 cycles of induction chemotherapy with EP-HDFL (Epirubicin, Cisplatin, 5-FU, and Leucovorin). After induction chemotherapy, weekly based PFL was administered concurrent with HT. Radiation consisted of 70 Gy to the planning target volumes of the primary tumor plus any positive nodal disease using 2 Gy per fraction. After completion of induction chemotherapy, the response rates for primary and nodal disease were 96.4% and 80.8%, respectively. With a median follow-up after 33 months (Range, 13-53 months), there have been 2 primary and 1 nodal relapse after completion of radiotherapy. The estimated 3-year progression-free rates for local, regional, locoregional and distant metastasis survival rate were 92.4%, 95.7%, 88.4%, and 78.0%, respectively. The estimated 3-year overall survival was 83.5%. Acute grade 3, 4 toxicities for xerostomia and dermatitis were only 3.6% and 10.7%, respectively. HT for locoregionally advanced NPC is feasible and effective in regard to locoregional control with high compliance, even after neoadjuvant chemotherapy. None of out-field or marginal failure noted in the current study confirms the potential benefits of treating NPC patients by image-guided radiation modality. A long-term follow-up study is needed to confirm these preliminary findings

An enhanced block matching algorithm for fast elastic registration in adaptive radiotherapy

International Nuclear Information System (INIS)

Malsch, U; Thieke, C; Huber, P E; Bendl, R

2006-01-01

Image registration has many medical applications in diagnosis, therapy planning and therapy. Especially for time-adaptive radiotherapy, an efficient and accurate elastic registration of images acquired for treatment planning, and at the time of the actual treatment, is highly desirable. Therefore, we developed a fully automatic and fast block matching algorithm which identifies a set of anatomical landmarks in a 3D CT dataset and relocates them in another CT dataset by maximization of local correlation coefficients in the frequency domain. To transform the complete dataset, a smooth interpolation between the landmarks is calculated by modified thin-plate splines with local impact. The concept of the algorithm allows separate processing of image discontinuities like temporally changing air cavities in the intestinal track or rectum. The result is a fully transformed 3D planning dataset (planning CT as well as delineations of tumour and organs at risk) to a verification CT, allowing evaluation and, if necessary, changes of the treatment plan based on the current patient anatomy without time-consuming manual re-contouring. Typically the total calculation time is less than 5 min, which allows the use of the registration tool between acquiring the verification images and delivering the dose fraction for online corrections. We present verifications of the algorithm for five different patient datasets with different tumour locations (prostate, paraspinal and head-and-neck) by comparing the results with manually selected landmarks, visual assessment and consistency testing. It turns out that the mean error of the registration is better than the voxel resolution (2 x 2 x 3 mm 3 ). In conclusion, we present an algorithm for fully automatic elastic image registration that is precise and fast enough for online corrections in an adaptive fractionated radiation treatment course

Intensity modulated radiotherapy (IMRT) in bilateral retinoblastoma

International Nuclear Information System (INIS)

Atalar, Banu; Ozyar, Enis; Gunduz, Kaan; Gungor, Gorkem

2010-01-01

External beam radiotherapy (EBRT) for retinoblastoma has traditionally been done with conventional radiotherapy techniques which resulted high doses to the surrounding normal tissues. A 20 month-old girl with group D bilateral retinoblastoma underwent intensity modulated radiotherapy (IMRT) to both eyes after failing chemoreduction and focal therapies including cryotherapy and transpupillary thermotherapy. In this report, we discuss the use of IMRT as a method for reducing doses to adjacent normal tissues while delivering therapeutic doses to the tumour tissues compared with 3-dimensional conformal radiotherapy (3DCRT). At one year follow-up, the patient remained free of any obvious radiation complications. Image guided IMRT provides better dose distribution than 3DCRT in retinoblastoma eyes, delivering the therapeutic dose to the tumours and minimizing adjacent tissue damage

Molecular image guided radiation therapy-MIGRT in radiobioluminescence and nanoradioguidance

International Nuclear Information System (INIS)

Rao, V.L. Papineni

2014-01-01

Accurate dose delivery to malignant tissue in radiotherapy is essential for enhancing the treatment efficacy while minimizing morbidity of surrounding normal tissues. Advances in therapeutic strategies and diagnosis technologies along with our understanding of the biology of tumor response to radiation therapy have paved way to allow nearly 60% of current cancer patients to be treated with Radiation Therapy. The confluence of molecular imaging and nanotechnology fields are bridging physics and medicine and are quickly making strides in opening new avenues and therapeutic strategies that complement radiation therapy - with a distinct footprint in immunotherapy, adoptive cell therapy, and targeted chemotherapy. Incorporating optical imaging in radiation therapy in my laboratory, endogenous bioluminescence resulting from whole body irradiation in different organs, and in different animals, which is distinct from the Cherenkov radiation. The endogenous bioluminescence in response to irradiation is coined recently as radiobioluminescence. Thus with the necessity, the design, construction, and validation of Molecular Image Guided Radiation Therapy (MIGRT) instrumentation for preclinical theragnostics is carried out

Treatment of Locally Advanced Vaginal Cancer With Radiochemotherapy and Magnetic Resonance Image-Guided Adaptive Brachytherapy: Dose–Volume Parameters and First Clinical Results

International Nuclear Information System (INIS)

Dimopoulos, Johannes C.A.; Schmid, Maximilian P.; Fidarova, Elena; Berger, Daniel; Kirisits, Christian; Pötter, Richard

2012-01-01

Purpose: To investigate the clinical feasibility of magnetic resonance image-guided adaptive brachytherapy (IGABT) for patients with locally advanced vaginal cancer and to report treatment outcomes. Methods and Materials: Thirteen patients with vaginal cancer were treated with external beam radiotherapy (45–50.4 Gy) plus IGABT with or without chemotherapy. Distribution of International Federation of Gynecology and Obstetrics stages among patients were as follows: 4 patients had Stage II cancer, 5 patients had Stage III cancer, and 4 patients had Stage IV cancer. The concept of IGABT as developed for cervix cancer was transferred and adapted for vaginal cancer, with corresponding treatment planning and reporting. Doses were converted to the equivalent dose in 2 Gy, applying the linear quadratic model (α/β = 10 Gy for tumor; α/β = 3 for organs at risk). Endpoints studied were gross tumor volume (GTV), dose-volume parameters for high-risk clinical target volume (HRCTV), and organs at risk, local control (LC), adverse side effects, and survival. Results: The mean GTV (± 1 standard deviation) at diagnosis was 45.3 (±30) cm 3 , and the mean GTV at brachytherapy was 10 (±14) cm 3 . The mean D90 for the HRCTV was 86 (±13) Gy. The mean D2cc for bladder, urethra, rectum, and sigmoid colon were 80 (±20) Gy, 76 (±16) Gy, 70 (±9) Gy, and 60 (±9) Gy, respectively. After a median follow-up of 43 months (range, 19–87 months), one local recurrence and two distant metastases cases were observed. Actuarial LC and overall survival rates at 3 years were 92% and 85%. One patient with Stage IVA and 1 patient with Stage III disease experienced fistulas (one vesicovaginal, one rectovaginal), and 1 patient developed periurethral necrosis. Conclusions: The concept of IGABT, originally developed for treating cervix cancer, appears to be applicable to vaginal cancer treatment with only minor adaptations. Dose-volume parameters for HRCTV and organs at risk are in a comparable

Treatment of Locally Advanced Vaginal Cancer With Radiochemotherapy and Magnetic Resonance Image-Guided Adaptive Brachytherapy: Dose-Volume Parameters and First Clinical Results

Energy Technology Data Exchange (ETDEWEB)

Dimopoulos, Johannes C.A. [Department of Radiation Oncology, Metropolitan Hospital, Athens (Greece); Schmid, Maximilian P., E-mail: maximilian.schmid@akhwien.at [Department of Radiotherapy, Medical University of Vienna, Vienna (Austria); Fidarova, Elena; Berger, Daniel; Kirisits, Christian; Poetter, Richard [Department of Radiotherapy, Medical University of Vienna, Vienna (Austria)

2012-04-01

Purpose: To investigate the clinical feasibility of magnetic resonance image-guided adaptive brachytherapy (IGABT) for patients with locally advanced vaginal cancer and to report treatment outcomes. Methods and Materials: Thirteen patients with vaginal cancer were treated with external beam radiotherapy (45-50.4 Gy) plus IGABT with or without chemotherapy. Distribution of International Federation of Gynecology and Obstetrics stages among patients were as follows: 4 patients had Stage II cancer, 5 patients had Stage III cancer, and 4 patients had Stage IV cancer. The concept of IGABT as developed for cervix cancer was transferred and adapted for vaginal cancer, with corresponding treatment planning and reporting. Doses were converted to the equivalent dose in 2 Gy, applying the linear quadratic model ({alpha}/{beta} = 10 Gy for tumor; {alpha}/{beta} = 3 for organs at risk). Endpoints studied were gross tumor volume (GTV), dose-volume parameters for high-risk clinical target volume (HRCTV), and organs at risk, local control (LC), adverse side effects, and survival. Results: The mean GTV ({+-} 1 standard deviation) at diagnosis was 45.3 ({+-}30) cm{sup 3}, and the mean GTV at brachytherapy was 10 ({+-}14) cm{sup 3}. The mean D90 for the HRCTV was 86 ({+-}13) Gy. The mean D2cc for bladder, urethra, rectum, and sigmoid colon were 80 ({+-}20) Gy, 76 ({+-}16) Gy, 70 ({+-}9) Gy, and 60 ({+-}9) Gy, respectively. After a median follow-up of 43 months (range, 19-87 months), one local recurrence and two distant metastases cases were observed. Actuarial LC and overall survival rates at 3 years were 92% and 85%. One patient with Stage IVA and 1 patient with Stage III disease experienced fistulas (one vesicovaginal, one rectovaginal), and 1 patient developed periurethral necrosis. Conclusions: The concept of IGABT, originally developed for treating cervix cancer, appears to be applicable to vaginal cancer treatment with only minor adaptations. Dose-volume parameters for HRCTV and

Hypofractionated image-guided breath-hold SABR (Stereotactic Ablative Body Radiotherapy of liver metastases – clinical results

Directory of Open Access Journals (Sweden)

Boda-Heggemann Judit

2012-06-01

Full Text Available 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 3 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

SU-E-J-14: A Novel Approach to Evaluate the Dosimetric Effect of Rectal Variation During Image Guided Prostate Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Murray, J [The Institute of Cancer Research, London (United Kingdom); McQuaid, D; Dunlop, A; Nill, S; Gulliford, S [Joint Department of Physics at The Institute of Cancer Research and The Royal Marsden, London (United Kingdom); Buettner, F [Helmholtz Zentrum Munchen - German Research Center for Environmental Healt, Neuherberg (Germany); Hall, E [Clinical Trials and Statistics Unit, The Institute of Cancer Research, London (United Kingdom); Dearnaley, D [The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London (United Kingdom)

2014-06-01

Purpose: Deformable registration establishes the spatial correspondence back to the reference image in order to accumulate dose. However, in prostate radiotherapy the changing shape and volume of the rectum present a challenge to accurate deformable registration and consequently calculation of delivered dose. We explored an alternative approach to calculating accumulated dose to the rectum, independent of deformable registration. Methods: This study was performed on three patients who received online image-guided radiotherapy (IGRT) with daily CBCT (XVI-system,Elekta) and target localization using intraprostatic fiducials. On each CBCT, the rectum was manually contoured and bulk density assignments were made allowing dose to be calculated for each fraction. Dose-surface maps (DSM) were generated (MATLAB,Mathworks,Natick,MA) by considering the rectum as a cylinder and sampling the dose at 21-equispaced points on each CT slice. The cylinder was “cut” at the posterior-most position on each CT and unfolded to generate a DSM. These were normalised in the longitudinal direction by interpolation creating maps of 21×21 pixels. A DSM was produced for each CBCT and the dose was accumulated. Results: The mean accumulated delivered rectal surface dose was on average 7.5(+/−3.5)% lower than the planned dose. The dose difference maps consistently show that the greatest variation in dose between planned and delivered dose is away from where the rectal surface is adjacent to the prostate. Conclusion: Estimation of dose accumulation using DSM provides an alternative method for determining actual delivered dose to the rectum. The dose difference is greatest in areas away from the region where the rectal surface abuts the prostate, the region where set-up is verified. The change in size and shape of the rectum was shown to resultin a change in the accumulated dose compared to the planned dose and this will have an impact on determining the relationships between dose delivered

Review of potential improvements using MRI in the radiotherapy workflow

International Nuclear Information System (INIS)

Torresin, Alberto; Brambilla, Maria Grazia; Monti, Angelo F.; Moscato, Alessio; Brockmann, Marc A.; University Medical Center Mannheim; Schad, Lothar; Attenberger, Ulrike I.; Lohr, Frank

2015-01-01

The goal of modern radiotherapy is to deliver a lethal amount of dose to tissue volumes that contain a significant amount of tumour cells while sparing surrounding unaffected or healthy tissue. Online image guided radiotherapy with stereotactic ultrasound, fiducial-based planar X-ray imaging or helical/conebeam CT has dramatically improved the precision of radiotherapy, with moving targets still posing some methodical problems regarding positioning. Therefore, requirements for precise target delineation and identification of functional body structures to be spared by high doses become more evident. The identification of areas of relatively radioresistant cells or areas of high tumor cell density is currently under development. This review outlines the state of the art of MRI integration into treatment planning and its importance in follow up and the quantification of biological effects. Finally the current state of the art of online imaging for patient positioning will be outlined and indications will be given what the potential of integrated radiotherapy/online MRI systems is.

Impact of different setup approaches in image-guided radiotherapy as primary treatment for prostate cancer. A study of 2940 setup deviations in 980 MVCTs

International Nuclear Information System (INIS)

Schiller, Kilian; Specht, Hanno; Kampfer, Severin; Duma, Marciana Nona; Petrucci, Alessia; Geinitz, Hans; Schuster, Tibor

2014-01-01

The goal of this study was to assess the impact of different setup approaches in image-guided radiotherapy (IMRT) of the prostatic gland. In all, 28 patients with prostate cancer were enrolled in this study. After the placement of an endorectal balloon, the planning target volume (PTV) was treated to a dose of 70 Gy in 35 fractions. A simultaneously integrated boost (SIB) of 76 Gy (2.17 Gy per fraction and per day) was delivered to a smaller target volume. All patients underwent daily prostate-aligned IGRT by megavoltage CT (MVCT). Retrospectively, three different setup approaches were evaluated by comparison to the prostate alignment: setup by skin alignment, endorectal balloon alignment, and automatic registration by bones. A total of 2,940 setup deviations were analyzed in 980 fractions. Compared to prostate alignment, skin mark alignment was associated with substantial displacements, which were ≥ 8 mm in 13 %, 5 %, and 44 % of all fractions in the lateral, longitudinal, and vertical directions, respectively. Endorectal balloon alignment yielded displacements ≥ 8 mm in 3 %, 19 %, and 1 % of all setups; and ≥ 3 mm in 27 %, 58 %, and 18 % of all fractions, respectively. For bone matching, the values were 1 %, 1 %, and 2 % and 3 %, 11 %, and 34 %, respectively. For prostate radiotherapy, setup by skin marks alone is inappropriate for patient positioning due to the fact that, during almost half of the fractions, parts of the prostate would not be targeted successfully with an 8-mm safety margin. Bone matching performs better but not sufficiently for safety margins ≤ 3 mm. Endorectal balloon matching can be combined with bone alignment to increase accuracy in the vertical direction when prostate-based setup is not available. Daily prostate alignment remains the gold standard for high-precision radiotherapy with small safety margins. (orig.) [de

Processing and evaluation of image matching tools in radiotherapy

International Nuclear Information System (INIS)

Bondiau, P.Y.

2004-11-01

Cancer is a major problem of public health. Treatment can be done in a general or loco-regional way, in this last case medical images are important as they specify the localization of the tumour. The objective of the radiotherapy is to deliver a curative dose of radiation in the target volume while sparing the organs at risks (O.A.R.). The determination of the accurate localization of the targets volume as well as O.A.R. make it possible to define the ballistic of irradiation beams. After the description of the principles of radiotherapy and cancers treatment, we specify the clinical stakes of ocular, cerebral and prostatic tumours. We present a state of the art of image matching, the various techniques reviewed with an aim of being didactic with respect to the medical community. The results of matching are presented within the framework of the planning of the cerebral and prostatic radiotherapy in order to specify the types of applicable matching in oncology and more particularly in radiotherapy. Then, we present the prospects for this type of application according to various anatomical areas. Applications of automatic segmentation and the evaluation of the results in the framework of brain tumour are described after a review of the various segmentation methods according to anatomical localizations. We will see an original application: the digital simulation of the virtual tumoral growth and the comparison with the real growth of a cerebral tumour presented by a patient. Lastly, we will expose the future developments possible of the tools for image processing in radiotherapy as well as the tracks of research to be explored in oncology. (author)

MR image-guided portal verification for brain treatment field

International Nuclear Information System (INIS)

Yin Fangfang; Gao Qinghuai; Xie Huchen; Nelson, Diana F.; Yu Yan; Kwok, W. Edmund; Totterman, Saara; Schell, Michael C.; Rubin, Philip

1998-01-01

Purpose: To investigate a method for the generation of digitally reconstructed radiographs directly from MR images (DRR-MRI) to guide a computerized portal verification procedure. Methods and Materials: Several major steps were developed to perform an MR image-guided portal verification procedure. Initially, a wavelet-based multiresolution adaptive thresholding method was used to segment the skin slice-by-slice in MR brain axial images. Some selected anatomical structures, such as target volume and critical organs, were then manually identified and were reassigned to relatively higher intensities. Interslice information was interpolated with a directional method to achieve comparable display resolution in three dimensions. Next, a ray-tracing method was used to generate a DRR-MRI image at the planned treatment position, and the ray tracing was simply performed on summation of voxels along the ray. The skin and its relative positions were also projected to the DRR-MRI and were used to guide the search of similar features in the portal image. A Canny edge detector was used to enhance the brain contour in both portal and simulation images. The skin in the brain portal image was then extracted using a knowledge-based searching technique. Finally, a Chamfer matching technique was used to correlate features between DRR-MRI and portal image. Results: The MR image-guided portal verification method was evaluated using a brain phantom case and a clinical patient case. Both DRR-CT and DRR-MRI were generated using CT and MR phantom images with the same beam orientation and then compared. The matching result indicated that the maximum deviation of internal structures was less than 1 mm. The segmented results for brain MR slice images indicated that a wavelet-based image segmentation technique provided a reasonable estimation for the brain skin. For the clinical patient case with a given portal field, the MR image-guided verification method provided an excellent match between

An investigation into the use of CMOS active pixel technology in image-guided radiotherapy

International Nuclear Information System (INIS)

Osmond, J P F; Holland, A D; Harris, E J; Ott, R J; Evans, P M; Clark, A T

2008-01-01

The increased intelligence, read-out speed, radiation hardness and potential large size of CMOS active pixel sensors (APS) gives them a potential advantage over systems currently used for verification of complex treatments such as IMRT and the tracking of moving tumours. The aim of this work is to investigate the feasibility of using an APS-based system to image the megavoltage treatment beam produced by a linear accelerator (Linac), and to demonstrate the logic which may ultimately be incorporated into future sensor and FPGA design to evaluate treatment and track motion. A CMOS APS was developed by the MI 3 consortium and incorporated into a megavoltage imaging system using the standard lens and mirror configuration employed in camera-based EPIDs. The ability to resolve anatomical structure was evaluated using an Alderson RANDO head phantom, resolution evaluated using a quality control (QC3) phantom and contrast using an in-house developed phantom. A complex intensity-modulated radiotherapy (IMRT) treatment was imaged and two algorithms were used to determine the field-area and delivered dose, and the position of multi-leaf collimator (MLC) leaves off-line. Results were compared with prediction from the prescription and found to agree within a single image frame time for dose delivery and 0.02-0.03 cm for the position of collimator leaves. Such a system therefore shows potential as the basis for an on-line verification system capable of treatment verification and monitoring patient motion

Accuracy of image guidance using free-breathing cone-beam computed tomography for stereotactic lung radiotherapy.

Science.gov (United States)

Kamomae, Takeshi; Monzen, Hajime; Nakayama, Shinichi; Mizote, Rika; Oonishi, Yuuichi; Kaneshige, Soichiro; Sakamoto, Takashi

2015-01-01

Movement of the target object during cone-beam computed tomography (CBCT) leads to motion blurring artifacts. The accuracy of manual image matching in image-guided radiotherapy depends on the image quality. We aimed to assess the accuracy of target position localization using free-breathing CBCT during stereotactic lung radiotherapy. The Vero4DRT linear accelerator device was used for the examinations. Reference point discrepancies between the MV X-ray beam and the CBCT system were calculated using a phantom device with a centrally mounted steel ball. The precision of manual image matching between the CBCT and the averaged intensity (AI) images restructured from four-dimensional CT (4DCT) was estimated with a respiratory motion phantom, as determined in evaluations by five independent operators. Reference point discrepancies between the MV X-ray beam and the CBCT image-guidance systems, categorized as left-right (LR), anterior-posterior (AP), and superior-inferior (SI), were 0.33 ± 0.09, 0.16 ± 0.07, and 0.05 ± 0.04 mm, respectively. The LR, AP, and SI values for residual errors from manual image matching were -0.03 ± 0.22, 0.07 ± 0.25, and -0.79 ± 0.68 mm, respectively. The accuracy of target position localization using the Vero4DRT system in our center was 1.07 ± 1.23 mm (2 SD). This study experimentally demonstrated the sufficient level of geometric accuracy using the free-breathing CBCT and the image-guidance system mounted on the Vero4DRT. However, the inter-observer variation and systematic localization error of image matching substantially affected the overall geometric accuracy. Therefore, when using the free-breathing CBCT images, careful consideration of image matching is especially important.

Adaptive Radiotherapy for Locally Advanced Non–Small-Cell Lung Cancer Does Not Underdose the Microscopic Disease and has the Potential to Increase Tumor Control

International Nuclear Information System (INIS)

Guckenberger, Matthias; Richter, Anne; Wilbert, Juergen; Flentje, Michael; Partridge, Mike

2011-01-01

Purpose: To evaluate doses to the microscopic disease (MD) in adaptive radiotherapy (ART) for locally advanced non–small-cell lung cancer (NSCLC) and to model tumor control probability (TCP). Methods and Materials: In a retrospective planning study, three-dimensional conformal treatment plans for 13 patients with locally advanced NSCLC were adapted to shape and volume changes of the gross tumor volume (GTV) once or twice during conventionally fractionated radiotherapy with total doses of 66 Gy; doses in the ART plans were escalated using an iso-mean lung dose (MLD) approach compared to non-adapted treatment. Dose distributions to the volumes of suspect MD were simulated for a scenario with synchronous shrinkage of the MD and GTV and for a scenario of a stationary MD despite GTV shrinkage; simulations were performed using deformable image registration. TCP calculations considering doses to the GTV and MD were performed using three different models. Results: Coverage of the MD at 50 Gy was not compromised by ART. Coverage at 60 Gy in the scenario of a stationary MD was significantly reduced from 92% ± 10% to 73% ± 19% using ART; however, the coverage was restored by iso-MLD dose escalation. Dose distributions in the MD were sufficient to achieve a TCP >80% on average in all simulation experiments, with the clonogenic cell density the major factor influencing TCP. The combined TCP for the GTV and MD was 19.9% averaged over all patients and TCP models in non-adaptive treatment with 66 Gy. Iso-MLD dose escalation achieved by ART increased the overall TCP by absolute 6% (adapting plan once) and by 8.7% (adapting plan twice) on average. Absolute TCP values were significantly different between the TCP models; however, all TCP models suggested very similar TCP increase by using ART. Conclusions: Adaptation of radiotherapy to the shrinking GTV did not compromise dose coverage of volumes of suspect microscopic disease and has the potential to increase TCP by >40% compared

Prospective feasibility analysis of a novel off-line approach for MR-guided radiotherapy.

Science.gov (United States)

Bostel, Tilman; Pfaffenberger, Asja; Delorme, Stefan; Dreher, Constantin; Echner, Gernot; Haering, Peter; Lang, Clemens; Splinter, Mona; Laun, Frederik; Müller, Marco; Jäkel, Oliver; Debus, Jürgen; Huber, Peter E; Sterzing, Florian; Nicolay, Nils H

2018-05-01

The present work aimed to analyze the feasibility of a shuttle-based MRI-guided radiation therapy (MRgRT) in the treatment of pelvic malignancies. 20 patients with pelvic malignancies were included in this prospective feasibility analysis. Patients underwent daily MRI in treatment position prior to radiotherapy at the German Cancer Research Center. Positional inaccuracies, time and patient compliance were assessed for the application of off-line MRgRT. In 78% of applied radiation fractions, MR imaging for position verification could be performed without problems. Additionally, treatment-related side effects and reduced patient compliance were only responsible for omission of MRI in 9% of radiation fractions. The study workflow took a median time of 61 min (range 47-99 min); duration for radiotherapy alone was 13 min (range 7-26 min). Patient positioning, MR imaging and CT imaging including patient repositioning and the shuttle transfer required median times of 10 min (range 7-14 min), 26 min (range 15-60 min), 5 min (range 3-8 min) and 8 min (range 2-36 min), respectively. To assess feasibility of shuttle-based MRgRT, the reference point coordinates for the x, y and z axis were determined for the MR images and CT obtained prior to the first treatment fraction and correlated with the coordinates of the planning CT. In our dataset, the median positional difference between MR imaging and CT-based imaging based on fiducial matching between MR and CT imaging was equal to or less than 2 mm in all spatial directions. The limited space in the MR scanner influenced patient selection, as the bore of the scanner had to accommodate the immobilization device and the constructed stereotactic frame. Therefore, obese, extremely muscular or very tall patients could not be included in this trial in addition to patients for whom exposure to MRI was generally judged inappropriate. This trial demonstrated for the first time the feasibility and patient

Prospective phase II trial of image-guided radiotherapy in Hodgkin lymphoma

DEFF Research Database (Denmark)

Petersen, Peter M; Aznar, Marianne C; Berthelsen, Anne K

2015-01-01

BACKGROUND: Long-term Hodgkin lymphoma (HL) survivors have an increased risk of late cardiac morbidity and secondary lung cancer after chemotherapy and mediastinal radiotherapy. In this prospective study we investigate whether radiotherapy with deep inspiration breath-hold (DIBH) can reduce...... radiation doses to the lungs, heart, and cardiac structures without compromising the target dose. PATIENTS AND METHODS: Twenty-two patients (14 female, 8 male), median age 30 years (18-65 years), with supra-diaphragmatic HL were enrolled and had a thoracic PET/CT with DIBH in addition to staging FDG...... retrospectively. Patients were treated with the technique yielding the lowest doses to normal structures. RESULTS: Nineteen patients were treated with DIBH and three with FB. DIBH reduced the mean estimated lung dose by 2.0 Gy (median: 8.5 Gy vs. 7.2 Gy) (p 4 Gy (6.0 Gy vs. 3...

A high-precision system for conformal intracranial radiotherapy

International Nuclear Information System (INIS)

Tome, Wolfgang A.; Meeks, Sanford L.; Buatti, John M.; Bova, Francis J.; Friedman, William A.; Li Zuofeng

2000-01-01

Purpose: Currently, optimally precise delivery of intracranial radiotherapy is possible with stereotactic radiosurgery and fractionated stereotactic radiotherapy. We report on an optimally precise optically guided system for three-dimensional (3D) conformal radiotherapy using multiple noncoplanar fixed fields. Methods and Materials: The optically guided system detects infrared light emitting diodes (IRLEDs) attached to a custom bite plate linked to the patient's maxillary dentition. The IRLEDs are monitored by a commercially available stereo camera system, which is interfaced to a personal computer. An IRLED reference is established with the patient at the selected stereotactic isocenter, and the computer reports the patient's current position based on the location of the IRLEDs relative to this reference position. Using this readout from the computer, the patient may be dialed directly to the desired position in stereotactic space. The patient is localized on the first day and a reference file is established for 5 different couch positions. The patient's image data are then imported into a commercial convolution-based 3D radiotherapy planning system. The previously established isocenter and couch positions are then used as a template upon which to design a conformal 3D plan with maximum beam separation. Results: The use of the optically guided system in conjunction with noncoplanar radiotherapy treatment planning using fixed fields allows the generation of highly conformal treatment plans that exhibit a high degree of dose homogeneity and a steep dose gradient. To date, this approach has been used to treat 28 patients. Conclusion: Because IRLED technology improves the accuracy of patient localization relative to the linac isocenter and allows real-time monitoring of patient position, one can choose treatment-field margins that only account for beam penumbra and image resolution without adding margin to account for larger and poorly defined setup uncertainty. This

Personalized Assessment of kV Cone Beam Computed Tomography Doses in Image-guided Radiotherapy of Pediatric Cancer Patients

Energy Technology Data Exchange (ETDEWEB)

Zhang Yibao [Beijing Key Lab of Medical Physics and Engineering, Peking University, Beijing (China); Yan Yulong [Department of Radiation Oncology, University of Arkansas for Medical Sciences, Little Rock, Arkansas (United States); Nath, Ravinder [Department of Therapeutic Radiology, Yale University, New Haven, Connecticut (United States); Bao Shanglian [Beijing Key Lab of Medical Physics and Engineering, Peking University, Beijing (China); Deng Jun, E-mail: jun.deng@yale.edu [Department of Therapeutic Radiology, Yale University, New Haven, Connecticut (United States)

2012-08-01

Purpose: To develop a quantitative method for the estimation of kV cone beam computed tomography (kVCBCT) doses in pediatric patients undergoing image-guided radiotherapy. Methods and Materials: Forty-two children were retrospectively analyzed in subgroups of different scanned regions: one group in the head-and-neck and the other group in the pelvis. Critical structures in planning CT images were delineated on an Eclipse treatment planning system before being converted into CT phantoms for Monte Carlo simulations. A benchmarked EGS4 Monte Carlo code was used to calculate three-dimensional dose distributions of kVCBCT scans with full-fan high-quality head or half-fan pelvis protocols predefined by the manufacturer. Based on planning CT images and structures exported in DICOM RT format, occipital-frontal circumferences (OFC) were calculated for head-and-neck patients using DICOMan software. Similarly, hip circumferences (HIP) were acquired for the pelvic group. Correlations between mean organ doses and age, weight, OFC, and HIP values were analyzed with SigmaPlot software suite, where regression performances were analyzed with relative dose differences (RDD) and coefficients of determination (R{sup 2}). Results: kVCBCT-contributed mean doses to all critical structures decreased monotonically with studied parameters, with a steeper decrease in the pelvis than in the head. Empirical functions have been developed for a dose estimation of the major organs at risk in the head and pelvis, respectively. If evaluated with physical parameters other than age, a mean RDD of up to 7.9% was observed for all the structures in our population of 42 patients. Conclusions: kVCBCT doses are highly correlated with patient size. According to this study, weight can be used as a primary index for dose assessment in both head and pelvis scans, while OFC and HIP may serve as secondary indices for dose estimation in corresponding regions. With the proposed empirical functions, it is possible

TU-AB-202-06: Quantitative Evaluation of Deformable Image Registration in MRI-Guided Adaptive Radiation Therapy

International Nuclear Information System (INIS)

Mooney, K; Zhao, T; Green, O; Mutic, S; Yang, D; Duan, Y; Zhang, M

2016-01-01

Purpose: To assess the performance of the deformable image registration algorithm used for MRI-guided adaptive radiation therapy using image feature analysis. Methods: MR images were collected from five patients treated on the MRIdian (ViewRay, Inc., Oakwood Village, OH), a three head Cobalt-60 therapy machine with an 0.35 T MR system. The images were acquired immediately prior to treatment with a uniform 1.5 mm resolution. Treatment sites were as follows: head/neck, lung, breast, stomach, and bladder. Deformable image registration was performed using the ViewRay software between the first fraction MRI and the final fraction MRI, and the DICE similarity coefficient (DSC) for the skin contours was reported. The SIFT and Harris feature detection and matching algorithms identified point features in each image separately, then found matching features in the other image. The target registration error (TRE) was defined as the vector distance between matched features on the two image sets. Each deformation was evaluated based on comparison of average TRE and DSC. Results: Image feature analysis produced between 2000–9500 points for evaluation on the patient images. The average (± standard deviation) TRE for all patients was 3.3 mm (±3.1 mm), and the passing rate of TRE<3 mm was 60% on the images. The head/neck patient had the best average TRE (1.9 mm±2.3 mm) and the best passing rate (80%). The lung patient had the worst average TRE (4.8 mm±3.3 mm) and the worst passing rate (37.2%). DSC was not significantly correlated with either TRE (p=0.63) or passing rate (p=0.55). Conclusions: Feature matching provides a quantitative assessment of deformable image registration, with a large number of data points for analysis. The TRE of matched features can be used to evaluate the registration of many objects throughout the volume, whereas DSC mainly provides a measure of gross overlap. We have a research agreement with ViewRay Inc.

TU-AB-202-06: Quantitative Evaluation of Deformable Image Registration in MRI-Guided Adaptive Radiation Therapy

Energy Technology Data Exchange (ETDEWEB)

Mooney, K; Zhao, T; Green, O; Mutic, S; Yang, D [Washington University School of Medicine, Saint Louis, MO (United States); Duan, Y [University of Missouri, Columbia, Missouri (United States); Zhang, M [Oregon Health and Science University, Portland, Oregon (United States)

2016-06-15

Purpose: To assess the performance of the deformable image registration algorithm used for MRI-guided adaptive radiation therapy using image feature analysis. Methods: MR images were collected from five patients treated on the MRIdian (ViewRay, Inc., Oakwood Village, OH), a three head Cobalt-60 therapy machine with an 0.35 T MR system. The images were acquired immediately prior to treatment with a uniform 1.5 mm resolution. Treatment sites were as follows: head/neck, lung, breast, stomach, and bladder. Deformable image registration was performed using the ViewRay software between the first fraction MRI and the final fraction MRI, and the DICE similarity coefficient (DSC) for the skin contours was reported. The SIFT and Harris feature detection and matching algorithms identified point features in each image separately, then found matching features in the other image. The target registration error (TRE) was defined as the vector distance between matched features on the two image sets. Each deformation was evaluated based on comparison of average TRE and DSC. Results: Image feature analysis produced between 2000–9500 points for evaluation on the patient images. The average (± standard deviation) TRE for all patients was 3.3 mm (±3.1 mm), and the passing rate of TRE<3 mm was 60% on the images. The head/neck patient had the best average TRE (1.9 mm±2.3 mm) and the best passing rate (80%). The lung patient had the worst average TRE (4.8 mm±3.3 mm) and the worst passing rate (37.2%). DSC was not significantly correlated with either TRE (p=0.63) or passing rate (p=0.55). Conclusions: Feature matching provides a quantitative assessment of deformable image registration, with a large number of data points for analysis. The TRE of matched features can be used to evaluate the registration of many objects throughout the volume, whereas DSC mainly provides a measure of gross overlap. We have a research agreement with ViewRay Inc.

Stereotactic body radiotherapy: current strategies and future development

Science.gov (United States)

2016-01-01

Stereotactic body radiotherapy (SBRT) has emerged as the standard treatment for medically inoperable early-staged non-small cell lung cancer (NSCLC). The local control rate after SBRT is over 90%. Some forms of tumour motion management and image-guided radiation delivery techniques are the prerequisites for fulfilment of its goal to deliver a high radiation dose to the tumour target without overdosing surrounding normal tissues. In this review, the current strategies of tumour motion management will be discussed, followed by an overview of various image-guided radiotherapy (RT) systems and devices available for clinical practice. Besides medically inoperable stage I NSCLC, SBRT has also been widely adopted for treatment of oligometastasis involving the lungs. Its possible applications in various other cancer illnesses are under extensive exploration. The progress of SBRT is critically technology-dependent. With advancement of technology, the ideal of personalised, effective and yet safe SBRT is already on the horizon. PMID:27606082

Evaluation of accuracy of B-spline transformation-based deformable image registration with different parameter settings for thoracic images

International Nuclear Information System (INIS)

Kanai, Takayuki; Kadoya, Noriyuki; Ito, Kengo

2014-01-01

Deformable image registration (DIR) is fundamental technique for adaptive radiotherapy and image-guided radiotherapy. However, further improvement of DIR is still needed. We evaluated the accuracy of B-spline transformation-based DIR implemented in elastix. This registration package is largely based on the Insight Segmentation and Registration Toolkit (ITK), and several new functions were implemented to achieve high DIR accuracy. The purpose of this study was to clarify whether new functions implemented in elastix are useful for improving DIR accuracy. Thoracic 4D computed tomography images of ten patients with esophageal or lung cancer were studied. Datasets for these patients were provided by DIR-lab (dir-lab.com) and included a coordinate list of anatomical landmarks that had been manually identified. DIR between peak-inhale and peak-exhale images was performed with four types of parameter settings. The first one represents original ITK (Parameter 1). The second employs the new function of elastix (Parameter 2), and the third was created to verify whether new functions improve DIR accuracy while keeping computational time (Parameter 3). The last one partially employs a new function (Parameter 4). Registration errors for these parameter settings were calculated using the manually determined landmark pairs. 3D registration errors with standard deviation over all cases were 1.78 (1.57), 1.28 (1.10), 1.44 (1.09) and 1.36 (1.35) mm for Parameter 1, 2, 3 and 4, respectively, indicating that the new functions are useful for improving DIR accuracy, even while maintaining the computational time, and this B-spline-based DIR could be used clinically to achieve high-accuracy adaptive radiotherapy. (author)

MR image reconstruction via guided filter.

Science.gov (United States)

Huang, Heyan; Yang, Hang; Wang, Kang

2018-04-01

Magnetic resonance imaging (MRI) reconstruction from the smallest possible set of Fourier samples has been a difficult problem in medical imaging field. In our paper, we present a new approach based on a guided filter for efficient MRI recovery algorithm. The guided filter is an edge-preserving smoothing operator and has better behaviors near edges than the bilateral filter. Our reconstruction method is consist of two steps. First, we propose two cost functions which could be computed efficiently and thus obtain two different images. Second, the guided filter is used with these two obtained images for efficient edge-preserving filtering, and one image is used as the guidance image, the other one is used as a filtered image in the guided filter. In our reconstruction algorithm, we can obtain more details by introducing guided filter. We compare our reconstruction algorithm with some competitive MRI reconstruction techniques in terms of PSNR and visual quality. Simulation results are given to show the performance of our new method.

An adaptive radiotherapy planning strategy for bladder cancer using deformation vector fields

International Nuclear Information System (INIS)

Vestergaard, Anne; Kallehauge, Jesper Folsted; Petersen, Jørgen Breede Baltzer; Høyer, Morten; Søndergaard, Jimmi; Muren, Ludvig Paul

2014-01-01

Purpose: Adaptive radiotherapy (ART) has considerable potential in treatment of bladder cancer due to large inter-fractional changes in shape and size of the target. The aim of this study was to compare our clinically applied method for plan library creation that involves manual bladder delineations (Clin-ART) with a method using the deformation vector fields (DVFs) resulting from intensity-based deformable image registrations (DVF-based ART). Materials and methods: The study included thirteen patients with urinary bladder cancer who had daily cone beam CTs (CBCTs) acquired for set-up. In both ART strategies investigated, three plan selection volumes were generated using the CBCTs from the first four fractions; in Clin-ART boolean combinations of delineated bladders were used, while the DVF-based strategy applied combinations of the mean and standard deviation of patient-specific DVFs. The volume ratios (VRs) of the course-averaged PTV for the two ART strategies relative the non-adaptive PTV were calculated. Results: Both Clin-ART and DVF-based ART considerably reduced the course-averaged PTV, compared to non-adaptive RT. The VR for DVF-based ART was lower than for Clin-ART (0.65 vs. 0.73; p < 0.01). Conclusions: DVF-based ART for bladder irradiation has a considerable normal tissue sparing potential surpassing our already highly conformal clinically applied ART strategy

An adaptive radiotherapy planning strategy for bladder cancer using deformation vector fields.

Science.gov (United States)

Vestergaard, Anne; Kallehauge, Jesper Folsted; Petersen, Jørgen Breede Baltzer; Høyer, Morten; Søndergaard, Jimmi; Muren, Ludvig Paul

2014-09-01

Adaptive radiotherapy (ART) has considerable potential in treatment of bladder cancer due to large inter-fractional changes in shape and size of the target. The aim of this study was to compare our clinically applied method for plan library creation that involves manual bladder delineations (Clin-ART) with a method using the deformation vector fields (DVFs) resulting from intensity-based deformable image registrations (DVF-based ART). The study included thirteen patients with urinary bladder cancer who had daily cone beam CTs (CBCTs) acquired for set-up. In both ART strategies investigated, three plan selection volumes were generated using the CBCTs from the first four fractions; in Clin-ART boolean combinations of delineated bladders were used, while the DVF-based strategy applied combinations of the mean and standard deviation of patient-specific DVFs. The volume ratios (VRs) of the course-averaged PTV for the two ART strategies relative the non-adaptive PTV were calculated. Both Clin-ART and DVF-based ART considerably reduced the course-averaged PTV, compared to non-adaptive RT. The VR for DVF-based ART was lower than for Clin-ART (0.65 vs. 0.73; p<0.01). DVF-based ART for bladder irradiation has a considerable normal tissue sparing potential surpassing our already highly conformal clinically applied ART strategy. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Processing and evaluation of image matching tools in radiotherapy; Mise en oeuvre et evaluation d'outils de fusion d'image en radiotherapie

Energy Technology Data Exchange (ETDEWEB)

Bondiau, P.Y

2004-11-15

Cancer is a major problem of public health. Treatment can be done in a general or loco-regional way, in this last case medical images are important as they specify the localization of the tumour. The objective of the radiotherapy is to deliver a curative dose of radiation in the target volume while sparing the organs at risks (O.A.R.). The determination of the accurate localization of the targets volume as well as O.A.R. make it possible to define the ballistic of irradiation beams. After the description of the principles of radiotherapy and cancers treatment, we specify the clinical stakes of ocular, cerebral and prostatic tumours. We present a state of the art of image matching, the various techniques reviewed with an aim of being didactic with respect to the medical community. The results of matching are presented within the framework of the planning of the cerebral and prostatic radiotherapy in order to specify the types of applicable matching in oncology and more particularly in radiotherapy. Then, we present the prospects for this type of application according to various anatomical areas. Applications of automatic segmentation and the evaluation of the results in the framework of brain tumour are described after a review of the various segmentation methods according to anatomical localizations. We will see an original application: the digital simulation of the virtual tumoral growth and the comparison with the real growth of a cerebral tumour presented by a patient. Lastly, we will expose the future developments possible of the tools for image processing in radiotherapy as well as the tracks of research to be explored in oncology. (author)

Residual rotational set-up errors after daily cone-beam CT image guided radiotherapy of locally advanced cervical cancer

International Nuclear Information System (INIS)

Laursen, Louise Vagner; Elstrøm, Ulrik Vindelev; Vestergaard, Anne; Muren, Ludvig P.; Petersen, Jørgen Baltzer; Lindegaard, Jacob Christian; Grau, Cai; Tanderup, Kari

2012-01-01

Purpose: Due to the often quite extended treatment fields in cervical cancer radiotherapy, uncorrected rotational set-up errors result in a potential risk of target miss. This study reports on the residual rotational set-up error after using daily cone beam computed tomography (CBCT) to position cervical cancer patients for radiotherapy treatment. Methods and materials: Twenty-five patients with locally advanced cervical cancer had daily CBCT scans (650 CBCTs in total) prior to treatment delivery. We retrospectively analyzed the translational shifts made in the clinic prior to each treatment fraction as well as the residual rotational errors remaining after translational correction. Results: The CBCT-guided couch movement resulted in a mean translational 3D vector correction of 7.4 mm. Residual rotational error resulted in a target shift exceeding 5 mm in 57 of the 650 treatment fractions. Three patients alone accounted for 30 of these fractions. Nine patients had no shifts exceeding 5 mm and 13 patients had 5 or less treatment fractions with such shifts. Conclusion: Twenty-two of the 25 patients have none or few treatment fractions with target shifts larger than 5 mm due to residual rotational error. However, three patients display a significant number of shifts suggesting a more systematic set-up error.

A strategy to objectively evaluate the necessity of correcting detected target deviations in image guided radiotherapy

International Nuclear Information System (INIS)

Yue, Ning J.; Kim, Sung; Jabbour, Salma; Narra, Venkat; Haffty, Bruce G.

2007-01-01

Image guided radiotherapy technologies are being increasingly utilized in the treatment of various cancers. These technologies have enhanced the ability to detect temporal and spatial deviations of the target volume relative to planned radiation beams. Correcting these detected deviations may, in principle, improve the accuracy of dose delivery to the target. However, in many situations, a clinical decision has to be made as to whether it is necessary to correct some of the deviations since the relevant dosimetric impact may or may not be significant, and the corresponding corrective action may be either impractical or time consuming. Ideally this decision should be based on objective and reproducible criteria rather than subjective judgment. In this study, a strategy is proposed for the objective evaluation of the necessity of deviation correction during the treatment verification process. At the treatment stage, without any alteration from the planned beams, the treatment beams should provide the desired dose coverage to the geometric volume identical to the planning target volume (PTV). Given this fact, the planned dose distribution and PTV geometry were used to compute the dose coverage and PTV enclosure of the clinical target volume (CTV) that was detected from imaging during the treatment setup verification. The spatial differences between the detected CTV and the planning CTV are essentially the target deviations. The extent of the PTV enclosure of the detected CTV as well as its dose coverage were used as criteria to evaluate the necessity of correcting any of the target deviations. This strategy, in principle, should be applicable to any type of target deviations, including both target deformable and positional changes and should be independent of how the deviations are detected. The proposed strategy was used on two clinical prostate cancer cases. In both cases, gold markers were implanted inside the prostate for the purpose of treatment setup

Contrast-guided image interpolation.

Science.gov (United States)

Wei, Zhe; Ma, Kai-Kuang

2013-11-01

In this paper a contrast-guided image interpolation method is proposed that incorporates contrast information into the image interpolation process. Given the image under interpolation, four binary contrast-guided decision maps (CDMs) are generated and used to guide the interpolation filtering through two sequential stages: 1) the 45(°) and 135(°) CDMs for interpolating the diagonal pixels and 2) the 0(°) and 90(°) CDMs for interpolating the row and column pixels. After applying edge detection to the input image, the generation of a CDM lies in evaluating those nearby non-edge pixels of each detected edge for re-classifying them possibly as edge pixels. This decision is realized by solving two generalized diffusion equations over the computed directional variation (DV) fields using a derived numerical approach to diffuse or spread the contrast boundaries or edges, respectively. The amount of diffusion or spreading is proportional to the amount of local contrast measured at each detected edge. The diffused DV fields are then thresholded for yielding the binary CDMs, respectively. Therefore, the decision bands with variable widths will be created on each CDM. The two CDMs generated in each stage will be exploited as the guidance maps to conduct the interpolation process: for each declared edge pixel on the CDM, a 1-D directional filtering will be applied to estimate its associated to-be-interpolated pixel along the direction as indicated by the respective CDM; otherwise, a 2-D directionless or isotropic filtering will be used instead to estimate the associated missing pixels for each declared non-edge pixel. Extensive simulation results have clearly shown that the proposed contrast-guided image interpolation is superior to other state-of-the-art edge-guided image interpolation methods. In addition, the computational complexity is relatively low when compared with existing methods; hence, it is fairly attractive for real-time image applications.

Image guided prostate cancer treatments

Energy Technology Data Exchange (ETDEWEB)

Bard, Robert L. [Bard Cancer Center, Biofoundation for Angiogenesis Research and Development, New York, NY (United States); Fuetterer, Jurgen J. [Radboud Univ. Nijmegen, Medical Centre (Netherlands). Dept. of Radiology; Sperling, Dan (ed.) [Sperling Prostate Center, Alpha 3TMRI, New York, NY (United States)

2014-07-01

Systematic overview of the application of ultrasound and MRI in the diagnosis and treatment of diseases of the lower urinary tract. Detailed information on image-guided therapies, including focused ultrasound, photodynamic therapy, and microwave and laser ablation. Numerous high-quality illustrations based on high-end equipment. Represents the state of the art in Non Invasive Imaging and Minimally Invasive Ablation Treatment (MIAT). Image-Guided Prostate Cancer Treatments is a comprehensive reference and practical guide on the technology and application of ultrasound and MRI in the male pelvis, with special attention to the prostate. The book is organized into three main sections, the first of which is devoted to general aspects of imaging and image-guided treatments. The second section provides a systematic overview of the application of ultrasound and MRI to the diagnosis and treatment of diseases of the lower urinary tract. Performance of the ultrasound and MRI studies is explained, and the normal and abnormal pathological anatomy is reviewed. Correlation with the ultrasound in the same plane is provided to assist in understanding the MRI sequences. Biopsy and interventional procedures, ultrasound-MRI fusion techniques, and image-guided therapies, including focused ultrasound, photodynamic therapy, microwave and laser ablation, are all fully covered. The third section focuses on securing treatment effectiveness and the use of follow-up imaging to ensure therapeutic success and detect tumor recurrence at an early stage, which is vital given that prompt focal treatment of recurrence is very successful. Here, particular attention is paid to the role of Doppler ultrasound and DCE-MRI technologies. This book, containing a wealth of high-quality illustrations based on high-end equipment, will acquaint beginners with the basics of prostate ultrasound and MRI, while more advanced practitioners will learn new skills, means of avoiding pitfalls, and ways of effectively

Evaluation of Online/Offline Image Guidance/Adaptation Approaches for Prostate Cancer Radiation Therapy

International Nuclear Information System (INIS)

Qin, An; Sun, Ying; Liang, Jian; Yan, Di

2015-01-01

Purpose: To evaluate online/offline image-guided/adaptive treatment techniques for prostate cancer radiation therapy with daily cone-beam CT (CBCT) imaging. Methods and Materials: Three treatment techniques were evaluated retrospectively using daily pre- and posttreatment CBCT images on 22 prostate cancer patients. Prostate, seminal vesicles (SV), rectal wall, and bladder were delineated on all CBCT images. For each patient, a pretreatment intensity modulated radiation therapy plan with clinical target volume (CTV) = prostate + SV and planning target volume (PTV) = CTV + 3 mm was created. The 3 treatment techniques were as follows: (1) Daily Correction: The pretreatment intensity modulated radiation therapy plan was delivered after online CBCT imaging, and position correction; (2) Online Planning: Daily online inverse plans with 3-mm CTV-to-PTV margin were created using online CBCT images, and delivered; and (3) Hybrid Adaption: Daily Correction plus an offline adaptive inverse planning performed after the first week of treatment. The adaptive plan was delivered for all remaining 15 fractions. Treatment dose for each technique was constructed using the daily posttreatment CBCT images via deformable image registration. Evaluation was performed using treatment dose distribution in target and critical organs. Results: Treatment equivalent uniform dose (EUD) for the CTV was within [85.6%, 100.8%] of the pretreatment planned target EUD for Daily Correction; [98.7%, 103.0%] for Online Planning; and [99.2%, 103.4%] for Hybrid Adaptation. Eighteen percent of the 22 patients in Daily Correction had a target dose deficiency >5%. For rectal wall, the mean ± SD of the normalized EUD was 102.6% ± 2.7% for Daily Correction, 99.9% ± 2.5% for Online Planning, and 100.6% ± 2.1% for Hybrid Adaptation. The mean ± SD of the normalized bladder EUD was 108.7% ± 8.2% for Daily Correction, 92.7% ± 8.6% for Online Planning, and 89.4% ± 10.8% for Hybrid

Intensity-Modulated Radiotherapy versus 3-Dimensional Conformal Radiotherapy Strategies for Locally Advanced Non-Small-Cell Lung Cancer

Directory of Open Access Journals (Sweden)

Uğur Selek

2014-12-01

Full Text Available Chemoradiotherapy is the current standard of care in patients with advanced inoperable stage IIIA or IIIB non-small cell lung cancer (NSCLC. Three-dimensional radiotherapy (3DCRT has been a trusted method for a long time and has well-known drawbacks, most of which could be improved by Intensity Modulated Radiotherapy (IMRT. IMRT is not currently the standard treatment of locally advanced NSCLC, but almost all patients could benefit to a degree in organ at risk sparing, dose coverage conformality, or dose escalation. The most critical step for a radiation oncology department is to strictly evaluate its own technical and physical capabilities to determine the ability of IMRT to deliver an optimal treatment plan. This includes calculating the internal tumor motion (ideally 4DCT or equivalent techniques, treatment planning software with an up-to-date heterogeneity correction algorithm, and daily image guidance. It is crucial to optimise and individualise the therapeutic ratio for each patient during the decision of 3DCRT versus IMRT. The current literature rationalises the increasing use of IMRT, including 4D imaging plus PET/CT, and encourages the applicable knowledge-based and individualised dose escalation using advanced daily image-guided radiotherapy.

Visibility of an iron-containing fiducial marker in magnetic resonance imaging for high-precision external beam prostate radiotherapy.

Science.gov (United States)

Tanaka, Osamu; Komeda, Hisao; Hirose, Shigeki; Taniguchi, Takuya; Ono, Kousei; Matsuo, Masayuki

2017-11-29

Visualization of fiducial gold markers is critical for registration on computed tomography (CT) and magnetic resonance imaging (MRI) for imaging-guided radiotherapy. Although larger markers provide better visualization on MRI, they tend to generate artifacts on CT. MRI is strongly influenced by the presence of metals, such as iron, in the body. Here we compared efficacies of a 0.5% iron-containing gold marker (GM) and a traditional non-iron-containing marker. Twenty-seven patients underwent CT/MRI fusion-based intensity-modulated radiotherapy. Markers were placed by urologists under local anesthesia. Gold Anchor (GA; diameter: 0.28 mm; length: 10 mm), an iron-containing marker, was placed on the right side of the prostate using a 22-G needle and VISICOIL (VIS; diameter: 0.35 mm; length: 10 mm), a non-iron-containing marker, was placed on the left side using a 19-G needle. T2*-weighted images MRI sequences were obtained. Two radiation oncologists and a radiation technologist evaluated and assigned scores for visual quality on a five-point scale (1, poor; 5, best visibility). Artifact generation on CT was slightly greater with GA than with VIS. The mean marker visualization scores on MRI of all three observers were significantly superior for GA than for VIS (3.5 vs 3.2, 3.9 vs 3.2, and 4.0 vs 2.9). The actual size of the spherical GA was about 2 mm in diameter, but the signal void on MRI was approximately 5 mm. Although both markers were well visualized and can be recommended clinically, the results suggest that GA has some subtle advantages for quantitative visualization that could prove useful in certain situations of stereotactic body radiotherapy and intensity-modulated radiotherapy. © 2017 John Wiley & Sons Australia, Ltd.

Image guided adaptive external beam radiation therapy for cervix cancer: Evaluation of a clinically implemented plan-of-the-day technique.