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Croke J, Maclean J, Nyiri B, Li Y, Malone K, Avruch L, Kayser C, Malone S. Proposal of a post-prostatectomy clinical target volume based on pre-operative MRI: volumetric and dosimetric comparison to the RTOG guidelines. Radiat Oncol 2014; 9:303. [PMID: 25534278 PMCID: PMC4307684 DOI: 10.1186/s13014-014-0303-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 12/14/2014] [Indexed: 12/15/2022] Open
Abstract
Background Recurrence rates following radiotherapy for prostate cancer in the post-operative adjuvant or salvage setting remain substantial. Previous work from our institution demonstrated that published prostate bed CTV guidelines frequently do not cover the pre-operative MRI defined prostate. Inadequate target delineation may contribute to the high recurrence rates, but increasing target volumes may increase dose to organs at risk. Methods We propose guidelines for delineating post-prostatectomy target volumes based upon an individual’s co-registered pre-operative MRI. MRI-based CTVs and PTVs were compared to those created using the RTOG guidelines in 30 patients. Contours were analysed in terms of absolute volume, intersection volume (Jaccard Index) and the ability to meet the RADICALS and QUANTEC rectal and bladder constraints (tomotherapy IMRT plans with PTV coverage of V98% ≥98%). Results CTV MRI was a mean of 18.6% larger than CTV RTOG: CTV MRI mean 138 cc (range 72.3 - 222.2 cc), CTV RTOG mean 116.3 cc (range 62.1 - 176.6 cc), (p < 0.0001). The difference in mean PTV was only 4.6%: PTV MRI mean 386.9 cc (range 254.4 – 551.2), PTV RTOG mean 370 cc (range 232.3 - 501.6) (p = 0.05). The mean Jaccard Index representing intersection volume between CTVs was 0.72 and 0.84 for PTVs. Both criteria had a similar ability to meet rectal and bladder constraints. Rectal DVH: 77% of CTV RTOG cases passed all RADICALS criteria and 37% all QUANTEC criteria; versus 73% and 40% for CTV MRI (p = 1.0 for both). Bladder DVH; 47% of CTV RTOG cases passed all RADICALS criteria and 67% all QUANTEC criteria, versus 57% and 60% for CTV MRI (p = 0.61for RADICALS, p = 0.79 for QUANTEC). CTV MRI spares more of the lower anterior bladder wall than CTV RTOG but increases coverage of the superior lateral bladder walls. Conclusion CTV contours based upon the patient’s co-registered pre-operative MRI in the post-prostatectomy setting may improve coverage of the individual’s prostate bed without substantially increasing the PTV size or dose to bladder/ rectum compared to RTOG CTV guidelines. Further evaluation of whether the use of pre-operative MRI improves local control rates is warranted.
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Affiliation(s)
- Jennifer Croke
- The Ottawa Hospital Cancer Centre, K1H 8 L6, Ottawa, Ontario, Canada.
| | - Jillian Maclean
- The Ottawa Hospital Cancer Centre, K1H 8 L6, Ottawa, Ontario, Canada.
| | - Balazs Nyiri
- The Ottawa Hospital Cancer Centre, K1H 8 L6, Ottawa, Ontario, Canada.
| | - Yan Li
- The Ottawa Hospital Cancer Centre, K1H 8 L6, Ottawa, Ontario, Canada.
| | - Kyle Malone
- The Ottawa Hospital Cancer Centre, K1H 8 L6, Ottawa, Ontario, Canada.
| | - Leonard Avruch
- The Ottawa Hospital Cancer Centre, K1H 8 L6, Ottawa, Ontario, Canada.
| | - Cathleen Kayser
- The Ottawa Hospital Cancer Centre, K1H 8 L6, Ottawa, Ontario, Canada.
| | - Shawn Malone
- The Ottawa Hospital Cancer Centre, K1H 8 L6, Ottawa, Ontario, Canada.
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Paulson ES, Erickson B, Schultz C, Allen Li X. Comprehensive MRI simulation methodology using a dedicated MRI scanner in radiation oncology for external beam radiation treatment planning. Med Phys 2014; 42:28-39. [DOI: 10.1118/1.4896096] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
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Moteabbed M, Schuemann J, Paganetti H. Dosimetric feasibility of real-time MRI-guided proton therapy. Med Phys 2014; 41:111713. [PMID: 25370627 PMCID: PMC4209014 DOI: 10.1118/1.4897570] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 08/06/2014] [Accepted: 09/15/2014] [Indexed: 01/13/2023] Open
Abstract
PURPOSE Magnetic resonance imaging (MRI) is a prime candidate for image-guided radiotherapy. This study was designed to assess the feasibility of real-time MRI-guided proton therapy by quantifying the dosimetric effects induced by the magnetic field in patients' plans and identifying the associated clinical consequences. METHODS Monte Carlo dose calculation was performed for nine patients of various treatment sites (lung, liver, prostate, brain, skull-base, and spine) and tissue homogeneities, in the presence of 0.5 and 1.5 T magnetic fields. Dose volume histogram (DVH) parameters such as D95, D5, and V20 as well as equivalent uniform dose were compared for the target and organs at risk, before and after applying the magnetic field. The authors further assessed whether the plans affected by clinically relevant dose distortions could be corrected independent of the planning system. RESULTS By comparing the resulting dose distributions and analyzing the respective DVHs, it was determined that despite the observed lateral beam deflection, for magnetic fields of up to 0.5 T, neither was the target coverage jeopardized nor was the dose to the nearby organs increased in all cases except for prostate. However, for a 1.5 T magnetic field, the dose distortions were more pronounced and of clinical concern in all cases except for spine. In such circumstances, the target was severely underdosed, as indicated by a decrease in D95 of up to 41% of the prescribed dose compared to the nominal situation (no magnetic field). Sites such as liver and spine were less affected due to higher tissue homogeneity, typically smaller beam range, and the choice of beam directions. Simulations revealed that small modifications to certain plan parameters such as beam isocenter (up to 19 mm) and gantry angle (up to 10°) are sufficient to compensate for the magnetic field-induced dose disturbances. The authors' observations indicate that the degree of required corrections strongly depends on the beam range and direction relative to the magnetic field. This method was also applicable to more heterogeneous scenarios such as skull-base tumors. CONCLUSIONS This study confirmed the dosimetric feasibility of real-time MRI-guided proton therapy and delivering a clinically acceptable dose to patients with various tumor locations within magnetic fields of up to 1.5 T. This work could serve as a guide and encouragement for further efforts toward clinical implementation of hybrid MRI-proton gantry systems.
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Affiliation(s)
- M Moteabbed
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - J Schuemann
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - H Paganetti
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
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Gudur MSR, Hara W, Le QT, Wang L, Xing L, Li R. A unifying probabilistic Bayesian approach to derive electron density from MRI for radiation therapy treatment planning. Phys Med Biol 2014; 59:6595-606. [PMID: 25321341 DOI: 10.1088/0031-9155/59/21/6595] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
MRI significantly improves the accuracy and reliability of target delineation in radiation therapy for certain tumors due to its superior soft tissue contrast compared to CT. A treatment planning process with MRI as the sole imaging modality will eliminate systematic CT/MRI co-registration errors, reduce cost and radiation exposure, and simplify clinical workflow. However, MRI lacks the key electron density information necessary for accurate dose calculation and generating reference images for patient setup. The purpose of this work is to develop a unifying method to derive electron density from standard T1-weighted MRI. We propose to combine both intensity and geometry information into a unifying probabilistic Bayesian framework for electron density mapping. For each voxel, we compute two conditional probability density functions (PDFs) of electron density given its: (1) T1-weighted MRI intensity, and (2) geometry in a reference anatomy, obtained by deformable image registration between the MRI of the atlas and test patient. The two conditional PDFs containing intensity and geometry information are combined into a unifying posterior PDF, whose mean value corresponds to the optimal electron density value under the mean-square error criterion. We evaluated the algorithm's accuracy of electron density mapping and its ability to detect bone in the head for eight patients, using an additional patient as the atlas or template. Mean absolute HU error between the estimated and true CT, as well as receiver operating characteristics for bone detection (HU > 200) were calculated. The performance was compared with a global intensity approach based on T1 and no density correction (set whole head to water). The proposed technique significantly reduced the errors in electron density estimation, with a mean absolute HU error of 126, compared with 139 for deformable registration (p = 2 × 10(-4)), 283 for the intensity approach (p = 2 × 10(-6)) and 282 without density correction (p = 5 × 10(-6)). For 90% sensitivity in bone detection, the proposed method achieved a specificity of 86%, compared with 80, 11 and 10% using deformable registration, intensity and without density correction, respectively. Notably, the Bayesian approach was more robust against anatomical differences between patients, with a specificity of 62% in the worst case (patient), compared to 30% specificity in registration-based approach. In conclusion, the proposed unifying Bayesian method provides accurate electron density estimation and bone detection from MRI of the head with highly heterogeneous anatomy.
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Korhonen J, Kapanen M, Keyriläinen J, Seppälä T, Tenhunen M. A dual model HU conversion from MRI intensity values within and outside of bone segment for MRI-based radiotherapy treatment planning of prostate cancer. Med Phys 2014; 41:011704. [PMID: 24387496 DOI: 10.1118/1.4842575] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The lack of electron density information in magnetic resonance images (MRI) poses a major challenge for MRI-based radiotherapy treatment planning (RTP). In this study the authors convert MRI intensity values into Hounsfield units (HUs) in the male pelvis and thus enable accurate MRI-based RTP for prostate cancer patients with varying tissue anatomy and body fat contents. METHODS T1/T2*-weighted MRI intensity values and standard computed tomography (CT) image HUs in the male pelvis were analyzed using image data of 10 prostate cancer patients. The collected data were utilized to generate a dual model HU conversion technique from MRI intensity values of the single image set separately within and outside of contoured pelvic bones. Within the bone segment local MRI intensity values were converted to HUs by applying a second-order polynomial model. This model was tuned for each patient by two patient-specific adjustments: MR signal normalization to correct shifts in absolute intensity level and application of a cutoff value to accurately represent low density bony tissue HUs. For soft tissues, such as fat and muscle, located outside of the bone contours, a threshold-based segmentation method without requirements for any patient-specific adjustments was introduced to convert MRI intensity values into HUs. The dual model HU conversion technique was implemented by constructing pseudo-CT images for 10 other prostate cancer patients. The feasibility of these images for RTP was evaluated by comparing HUs in the generated pseudo-CT images with those in standard CT images, and by determining deviations in MRI-based dose distributions compared to those in CT images with 7-field intensity modulated radiation therapy (IMRT) with the anisotropic analytical algorithm and 360° volumetric-modulated arc therapy (VMAT) with the Voxel Monte Carlo algorithm. RESULTS The average HU differences between the constructed pseudo-CT images and standard CT images of each test patient ranged from -2 to 5 HUs and from 22 to 78 HUs in soft and bony tissues, respectively. The average local absolute value differences were 11 HUs in soft tissues and 99 HUs in bones. The planning target volume doses (volumes 95%, 50%, 5%) in the pseudo-CT images were within 0.8% compared to those in CT images in all of the 20 treatment plans. The average deviation was 0.3%. With all the test patients over 94% (IMRT) and 92% (VMAT) of dose points within body (lower than 10% of maximum dose suppressed) passed the 1 mm and 1% 2D gamma index criterion. The statistical tests (t- and F-tests) showed significantly improved (p ≤ 0.05) HU and dose calculation accuracies with the soft tissue conversion method instead of homogeneous representation of these tissues in MRI-based RTP images. CONCLUSIONS This study indicates that it is possible to construct high quality pseudo-CT images by converting the intensity values of a single MRI series into HUs in the male pelvis, and to use these images for accurate MRI-based prostate RTP dose calculations.
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Affiliation(s)
- Juha Korhonen
- Clinical Research Institute Helsinki University Central Hospital Ltd., POB-700, 00029 HUS, Finland and Department of Oncology, Helsinki University Central Hospital, POB-180, 00029 HUS, Finland
| | - Mika Kapanen
- Clinical Research Institute Helsinki University Central Hospital Ltd., POB-700, 00029 HUS, Finland; Department of Oncology, Helsinki University Central Hospital, POB-180, 00029 HUS, Finland; and Department of Medical Physics, Tampere University Hospital, POB-2000, 33521 Tampere, Finland
| | - Jani Keyriläinen
- Department of Oncology, Helsinki University Central Hospital, POB-180, 00029 HUS, Finland
| | - Tiina Seppälä
- Department of Oncology, Helsinki University Central Hospital, POB-180, 00029 HUS, Finland
| | - Mikko Tenhunen
- Department of Oncology, Helsinki University Central Hospital, POB-180, 00029 HUS, Finland
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Bostel T, Nicolay NH, Grossmann JG, Mohr A, Delorme S, Echner G, Häring P, Debus J, Sterzing F. MR-guidance--a clinical study to evaluate a shuttle- based MR-linac connection to provide MR-guided radiotherapy. Radiat Oncol 2014; 9:12. [PMID: 24401489 PMCID: PMC3904210 DOI: 10.1186/1748-717x-9-12] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 12/13/2013] [Indexed: 11/10/2022] Open
Abstract
Background The purpose of this clinical study is to investigate the clinical feasibility and safety of a shuttle-based MR-linac connection to provide MR-guided radiotherapy. Methods/Design A total of 40 patients with an indication for a neoadjuvant, adjuvant or definitive radiation treatment will be recruited including tumors of the head and neck region, thorax, upper gastrointestinal tract and pelvic region. All study patients will receive standard therapy, i.e. highly conformal radiation techniques like CT-guided intensity-modulated radiotherapy (IMRT) with or without concomitant chemotherapy or other antitumor medication, and additionally daily short MR scans in treatment position with the same immobilisation equipment used for irradiation for position verification and imaging of the anatomical and functional changes during the course of radiotherapy. For daily position control, skin marks and a stereotactic frame will be used for both imaging modalities. Patient transfer between the MR device and the linear accelerator will be performed with a shuttle system which uses an air-bearing patient platform for both procedures. The daily acquired MR and CT data sets will be digitally registrated, correlated with the planning CT and compared with each other regarding translational and rotational errors. Aim of this clinical study is to establish a shuttle-based approach for realising MR-guided radiotherapy for certain clinical situations. Second objectives are to compare MR-guided radiotherapy with the gold standard of CT image guidance for quality assurance of radiotherapy, to establish an appropiate MR protocol therefore, and to assess the possibility of using MR-based image guidance not only for position verification but also for adaptive strategies in radiotherapy. Discussion Compared to CT, MRI might offer the advantage of providing IGRT without delivering an additional radiation dose to the patients and the possibility of optimisation of adaptive therapy strategies due to its superior soft tissue contrast. However, up to now, hybrid MR-linac devices are still under construction and not clinically applicable. For the near future, a shuttle-based approach would be a promising alternative for providing MR-guided radiotherapy, so that the present study was initiated to determine feasibility and safety of such an approach. Besides positioning information, daily MR data under treatment offer the possibility to assess tumor regression and functional parameters, with a potential impact not only on adaptive therapy strategies but also on early assessment of treatment response.
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Affiliation(s)
- Tilman Bostel
- Clinical Cooperation Unit Radiation Oncology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
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Wang YY, Zhe H. Clinical application of multimodality imaging in radiotherapy treatment planning for rectal cancer. Cancer Imaging 2013; 13:495-501. [PMID: 24334539 PMCID: PMC3864219 DOI: 10.1102/1470-7330.2013.0046] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Radiotherapy plays an important role in the treatment of rectal cancer. Three-dimensional conformal radiotherapy and intensity-modulated radiotherapy are mainstay techniques of radiotherapy for rectal cancer. However, the success of these techniques is heavily reliant on accurate target delineation and treatment planning. Computed tomography simulation is a cornerstone of rectal cancer radiotherapy, but there are limitations, such as poor soft-tissue contrast between pelvic structures and partial volume effects. Magnetic resonance imaging and positron emission tomography (PET) can overcome these limitations and provide additional information for rectal cancer treatment planning. PET can also reduce the interobserver variation in the definition of rectal tumor volume. However, there is a long way to go before these image modalities are routinely used in the clinical setting. This review summarizes the most promising studies on clinical applications of multimodality imaging in target delineation and treatment planning for rectal cancer radiotherapy.
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Affiliation(s)
- Yan Yang Wang
- Department of Radiation Oncology, General Hospital of Ningxia Medical University, Yinchuan, China
| | - Hong Zhe
- Department of Radiation Oncology, General Hospital of Ningxia Medical University, Yinchuan, China
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Pérez Romasanta LA, García Velloso MJ, López Medina A. Functional imaging in radiation therapy planning for head and neck cancer. Rep Pract Oncol Radiother 2013; 18:376-82. [PMID: 24416582 PMCID: PMC3863200 DOI: 10.1016/j.rpor.2013.10.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2013] [Revised: 10/16/2013] [Accepted: 10/16/2013] [Indexed: 11/22/2022] Open
Abstract
Functional imaging and its application to radiotherapy (RT) is a rapidly expanding field with new modalities and techniques constantly developing and evolving. As technologies improve, it will be important to pay attention to their implementation. This review describes the main achievements in the field of head and neck cancer (HNC) with particular remarks on the unsolved problems.
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Affiliation(s)
- Luis A. Pérez Romasanta
- Radiation Oncology, Hospital Universitario de Salamanca, Ps. San Vicente 58, 37007 Salamanca, Spain
| | | | - Antonio López Medina
- Medical Physics Department and Radiological Protection, Galaria – Hospital do Meixoeiro – Complexo Hospitalario Universitario de Vigo, Vigo, Spain
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Mouli SK, Tyler P, McDevitt JL, Eifler AC, Guo Y, Nicolai J, Lewandowski R.J, Li W, Procissi D, Ryu RK, Wang YA, Salem R, Larson AC, Omary RA. Image-guided local delivery strategies enhance therapeutic nanoparticle uptake in solid tumors. ACS NANO 2013; 7:7724-33. [PMID: 23952712 PMCID: PMC4012535 DOI: 10.1021/nn4023119] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Nanoparticles (NP) have emerged as a novel class of therapeutic agents that overcome many of the limitations of current cancer chemotherapeutics. However, a major challenge to many current NP platforms is unfavorable biodistribution, and limited tumor uptake, upon systemic delivery. Delivery, therefore, remains a critical barrier to widespread clinical adoption of NP therapeutics. To overcome these limitations, we have adapted the techniques of image-guided local drug delivery to develop nanoablation and nanoembolization. Nanoablation is a tumor ablative strategy that employs image-guided placement of electrodes into tumor tissue to electroporate tumor cells, resulting in a rapid influx of NPs that is not dependent on cellular uptake machinery or stage of the cell cycle. Nanoembolization involves the image-guided delivery of NPs and embolic agents directly into the blood supply of tumors. We describe the design and testing of our innovative local delivery strategies using doxorubicin-functionalized superparamagnetic iron oxide nanoparticles (DOX-SPIOs) in cell culture, and the N1S1 hepatoma and VX2 tumor models, imaged by high resolution 7T MRI. We demonstrate that local delivery techniques result in significantly increased intratumoral DOX-SPIO uptake, with limited off-target delivery in tumor-bearing animal models. The techniques described are versatile enough to be extended to any NP platform, targeting any solid organ malignancy that can be accessed via imaging guidance.
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Affiliation(s)
- Samdeep K. Mouli
- Department of Radiology, Section of Interventional Radiology, Northwestern Memorial Hospital, Robert H. Lurie Comprehensive Cancer Center, Chicago IL 60611
| | - Patrick Tyler
- Department of Radiology, Section of Interventional Radiology, Northwestern Memorial Hospital, Robert H. Lurie Comprehensive Cancer Center, Chicago IL 60611
| | - Joseph L. McDevitt
- Department of Radiology, Section of Interventional Radiology, Northwestern Memorial Hospital, Robert H. Lurie Comprehensive Cancer Center, Chicago IL 60611
| | - Aaron C. Eifler
- Department of Radiology, Section of Interventional Radiology, Northwestern Memorial Hospital, Robert H. Lurie Comprehensive Cancer Center, Chicago IL 60611
| | - Yang Guo
- Department of Radiology, Section of Interventional Radiology, Northwestern Memorial Hospital, Robert H. Lurie Comprehensive Cancer Center, Chicago IL 60611
| | - Jodi Nicolai
- Department of Radiology, Section of Interventional Radiology, Northwestern Memorial Hospital, Robert H. Lurie Comprehensive Cancer Center, Chicago IL 60611
| | - Robert .J. Lewandowski
- Department of Radiology, Section of Interventional Radiology, Northwestern Memorial Hospital, Robert H. Lurie Comprehensive Cancer Center, Chicago IL 60611
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611
| | - Weiguo Li
- Department of Radiology, Section of Interventional Radiology, Northwestern Memorial Hospital, Robert H. Lurie Comprehensive Cancer Center, Chicago IL 60611
| | - Daniel Procissi
- Department of Radiology, Section of Interventional Radiology, Northwestern Memorial Hospital, Robert H. Lurie Comprehensive Cancer Center, Chicago IL 60611
| | - Robert K. Ryu
- Department of Radiology, Section of Interventional Radiology, Northwestern Memorial Hospital, Robert H. Lurie Comprehensive Cancer Center, Chicago IL 60611
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611
| | - Y. Andrew Wang
- Ocean Nanotech, LLC, 700 Research Center Blvd., Fayetteville, AK 72701
| | - Riad Salem
- Department of Radiology, Section of Interventional Radiology, Northwestern Memorial Hospital, Robert H. Lurie Comprehensive Cancer Center, Chicago IL 60611
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611
| | - Andrew C. Larson
- Department of Radiology, Section of Interventional Radiology, Northwestern Memorial Hospital, Robert H. Lurie Comprehensive Cancer Center, Chicago IL 60611
- Department of Biomedical Engineering, Northwestern University, Chicago, IL 60611
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611
| | - Reed A. Omary
- Department of Radiology and Radiological Sciences, Vanderbilt University School of Medicine, Nashville, TN 37232
- Corresponding Author: Reed A. Omary, MD, MS, Carol D. & Henry P. Pendergrass Professor and Chairman, Department of Radiology and Radiological Sciences, Vanderbilt University School of Medicine, 1161 - 21st Avenue South, Medical Center North, Suite CCC-1106, Nashville TN 37232-2675, (615) 343-1187/Fax: (615) 343-8784,
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Chang JH, Lim Joon D, Nguyen BT, Hiew CY, Esler S, Angus D, Chao M, Wada M, Quong G, Khoo V. MRI scans significantly change target coverage decisions in radical radiotherapy for prostate cancer. J Med Imaging Radiat Oncol 2013; 58:237-43. [PMID: 24690247 DOI: 10.1111/1754-9485.12107] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2013] [Accepted: 07/25/2013] [Indexed: 12/29/2022]
Abstract
INTRODUCTION Conventional clinical staging for prostate cancer has many limitations. This study evaluates the impact of adding MRI scans to conventional clinical staging for guiding decisions about radiotherapy target coverage. METHODS This was a retrospective review of 115 patients who were treated between February 2002 and September 2005 with radical radiotherapy for prostate cancer. All patients had MRI scans approximately 2 weeks before the initiation of radiotherapy. The T stage was assessed by both conventional clinical methods (cT-staging) as well as by MRI (mT-staging). The radiotherapy target volumes were determined first based on cT-staging and then taking the additional mT staging into account. The number of times extracapsular extension or seminal vesicle invasion was incorporated into target volumes was quantified based on both cT-staging and the additional mT-staging. RESULTS Extracapsular extension was incorporated into target volumes significantly more often with the addition of mT-staging (46 patients (40%) ) compared with cT-staging alone (37 patients (32%) ) (P = 0.002). Seminal vesicle invasion was incorporated into target volumes significantly more often with the addition of mT-staging (21 patients (18%) ) compared with cT-staging alone (three patients (3%) ) (P < 0.001). A total of 23 patients (20%) had changes to their target coverage based on the mT-staging. CONCLUSIONS MRI scans can significantly change decisions about target coverage in radical radiotherapy for prostate cancer.
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Affiliation(s)
- Joe H Chang
- Radiation Oncology Centre, Austin Health, Melbourne, Victoria, Australia; Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia; University of Melbourne, Melbourne, Victoria, Australia
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Rischke HC, Nestle U, Fechter T, Doll C, Volegova-Neher N, Henne K, Scholber J, Knippen S, Kirste S, Grosu AL, Jilg CA. 3 Tesla multiparametric MRI for GTV-definition of Dominant Intraprostatic Lesions in patients with Prostate Cancer--an interobserver variability study. Radiat Oncol 2013; 8:183. [PMID: 23875672 PMCID: PMC3828667 DOI: 10.1186/1748-717x-8-183] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 07/20/2013] [Indexed: 01/28/2023] Open
Abstract
PURPOSE To evaluate the interobserver variability of gross tumor volume (GTV) - delineation of Dominant Intraprostatic Lesions (DIPL) in patients with prostate cancer using published MRI criteria for multiparametric MRI at 3 Tesla by 6 different observers. MATERIAL AND METHODS 90 GTV-datasets based on 15 multiparametric MRI sequences (T2w, diffusion weighted (DWI) and dynamic contrast enhanced (DCE)) of 5 patients with prostate cancer were generated for GTV-delineation of DIPL by 6 observers. The reference GTV-dataset was contoured by a radiologist with expertise in diagnostic imaging of prostate cancer using MRI. Subsequent GTV-delineation was performed by 5 radiation oncologists who received teaching of MRI-features of primary prostate cancer before starting contouring session. GTV-datasets were contoured using Oncentra Masterplan® and iplan® Net. For purposes of comparison GTV-datasets were imported to the Artiview® platform (Aquilab®), GTV-values and the similarity indices or Kappa indices (KI) were calculated with the postulation that a KI > 0.7 indicates excellent, a KI > 0.6 to < 0.7 substantial and KI > 0.5 to < 0.6 moderate agreement. Additionally all observers rated difficulties of contouring for each MRI-sequence using a 3 point rating scale (1 = easy to delineate, 2 = minor difficulties, 3 = major difficulties). RESULTS GTV contouring using T2w (KI-T2w = 0.61) and DCE images (KI-DCE = 0.63) resulted in substantial agreement. GTV contouring using DWI images resulted in moderate agreement (KI-DWI = 0.51). KI-T2w and KI-DCE was significantly higher than KI-DWI (p = 0.01 and p = 0.003). Degree of difficulty in contouring GTV was significantly lower using T2w and DCE compared to DWI-sequences (both p < 0.0001). Analysis of delineation differences revealed inadequate comparison of functional (DWI, DCE) to anatomical sequences (T2w) and lack of awareness of non-specific imaging findings as a source of erroneous delineation. CONCLUSIONS Using T2w and DCE sequences at 3 Tesla for GTV-definition of DIPL in prostate cancer patients by radiation oncologists with knowledge of MRI features results in substantial agreement compared to an experienced MRI-radiologist, but for radiotherapy purposes higher KI are desirable, strengthen the need for expert surveillance. DWI sequence for GTV delineation was considered as difficult in application.
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Affiliation(s)
- Hans Christian Rischke
- Department of Radiation Oncology, University of Freiburg, Robert Koch Str. 3, 79106 Freiburg, Germany.
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Brændengen M, Guren MG, Glimelius B. Target Volume Definition in Rectal Cancer: What Is the Best Imaging Modality? CURRENT COLORECTAL CANCER REPORTS 2013. [DOI: 10.1007/s11888-013-0170-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Hanvey S, McJury M, Tho LM, Glegg M, Thomson M, Grose D, James A, Rizwanullah M, Paterson C, Foster J. The influence of MRI scan position on patients with oropharyngeal cancer undergoing radical radiotherapy. Radiat Oncol 2013; 8:129. [PMID: 23714579 PMCID: PMC3681609 DOI: 10.1186/1748-717x-8-129] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 05/24/2013] [Indexed: 11/10/2022] Open
Abstract
Background The purpose of this study was to demonstrate how magnetic resonance imaging (MRI) patient position protocols influence registration quality in patients with oropharyngeal cancer undergoing radical radiotherapy and the consequences for gross tumour volume (GTV) definition and radiotherapy planning. Methods and materials Twenty-two oropharyngeal patients underwent a computed tomography (CT), a diagnostic MRI (MRID) and an MRI in the radiotherapy position within an immobilization mask (MRIRT). Clinicians delineated the GTV on the CT viewing the MRID separately (GTVC); on the CT registered to MRID (GTVD) and on the CT registered to MRIRT (GTVRT). Planning target volumes (PTVs) were denoted similarly. Registration quality was assessed by measuring disparity between structures in the three set-ups. Volumetric modulated arc therapy (VMAT) radiotherapy planning was performed for PTVC, PTVD and PTVRT. To determine the dose received by the reference PTVRT, we optimized for PTVC and PTVD while calculating the dose to PTVRT. Statistical significance was determined using the two-tailed Mann–Whitney or two-tailed paired student t-tests. Results A significant improvement in registration accuracy was found between CT and MRIRT versus the MRID measuring distances from the centre of structures (geometric mean error of 2.2 mm versus 6.6 mm). The mean GTVC (44.1 cm3) was significantly larger than GTVD (33.7 cm3, p value = 0.027) or GTVRT (30.5 cm3, p value = 0.014). When optimizing the VMAT plans for PTVC and investigating the mean dose to PTVRT neither the dose to 99% (58.8%) nor 95% of the PTV (84.7%) were found to meet the required clinical dose constraints of 90% and 95% respectively. Similarly, when optimizing for PTVD the mean dose to PTVRT did not meet clinical dose constraints for 99% (14.9%) nor 95% of the PTV (66.2%). Only by optimizing for PTVRT were all clinical dose constraints achieved. Conclusions When oropharyngeal patients MRI scans are performed in the radiotherapy position there are significant improvements in CT-MR image registration, target definition and PTV dose coverage.
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Nyholm T, Jonsson J, Söderström K, Bergström P, Carlberg A, Frykholm G, Behrens CF, Geertsen PF, Trepiakas R, Hanvey S, Sadozye A, Ansari J, McCallum H, Frew J, McMenemin R, Zackrisson B. Variability in prostate and seminal vesicle delineations defined on magnetic resonance images, a multi-observer, -center and -sequence study. Radiat Oncol 2013; 8:126. [PMID: 23706145 PMCID: PMC3680182 DOI: 10.1186/1748-717x-8-126] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 03/28/2013] [Indexed: 11/22/2022] Open
Abstract
Background The use of magnetic resonance (MR) imaging as a part of preparation for radiotherapy is increasing. For delineation of the prostate several publications have shown decreased delineation variability using MR compared to computed tomography (CT). The purpose of the present work was to investigate the intra- and inter-physician delineation variability for prostate and seminal vesicles, and to investigate the influence of different MR sequence settings used clinically at the five centers participating in the study. Methods MR series from five centers, each providing five patients, were used. Two physicians from each center delineated the prostate and the seminal vesicles on each of the 25 image sets. The variability between the delineations was analyzed with respect to overall, intra- and inter-physician variability, and dependence between variability and origin of the MR images, i.e. the MR sequence used to acquire the data. Results The intra-physician variability in different directions was between 1.3 - 1.9 mm and 3 – 4 mm for the prostate and seminal vesicles respectively (1 std). The inter-physician variability for different directions were between 0.7 – 1.7 mm and approximately equal for the prostate and seminal vesicles. Large differences in variability were observed for individual patients, and also for individual imaging sequences used at the different centers. There was however no indication of decreased variability with higher field strength. Conclusion The overall delineation variability is larger for the seminal vesicles compared to the prostate, due to a larger intra-physician variability. The imaging sequence appears to have a large influence on the variability, even for different variants of the T2-weighted spin-echo based sequences, which were used by all centers in the study.
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Yun J, Wachowicz K, Mackenzie M, Rathee S, Robinson D, Fallone BG. First demonstration of intrafractional tumor-tracked irradiation using 2D phantom MR images on a prototype linac-MR. Med Phys 2013; 40:051718. [DOI: 10.1118/1.4802735] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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Hanvey S, Sadozye AH, McJury M, Glegg M, Foster J. The influence of MRI scan position on image registration accuracy, target delineation and calculated dose in prostatic radiotherapy. Br J Radiol 2013; 85:e1256-62. [PMID: 23175491 DOI: 10.1259/bjr/26802977] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE To investigate the necessity of performing MRI in the radiotherapy position when using MRI for prostatic radiotherapy. METHODS 20 prostate patients received a CT, diagnostic MRI and an MRI scan in the radiotherapy position. The quality of registration between CT and MRI was compared between the two MRI set-ups. The prostate and seminal vesicles were contoured using all scans and intensity modulated radiotherapy (IMRT) plans were generated. Changes in the target volume and IMRT plans were investigated. Two-tailed paired Student's t-tests determined the statistical significance. RESULTS There was a decrease in the mean distance from the centre of the bony anatomy between CT and MRI (from 3.9 to 1.9 mm, p-value<0.0001) when the MRI scan was acquired in the radiotherapy position. Assuming that registering CT with an MRI scan in the radiotherapy position is the gold standard for delineating the prostate and seminal vesicles, using a planning target volume delineated on the CT with a diagnostic MRI scan viewed separately, resulted in a mean conformation number of 0.80 instead of the expected 0.98 (p<0.0001). CONCLUSION By registering CT with an MRI scan in the radiotherapy position, there is a statistically significant improvement in the registration and IMRT quality. ADVANCES IN KNOWLEDGE To achieve an acceptable registration and IMRT quality in prostatic radiotherapy, neither CT with a separate diagnostic MRI nor CT registered to a diagnostic MRI will suffice. Instead, a CT registered with an MRI in the radiotherapy position should be used.
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Affiliation(s)
- S Hanvey
- Department of Clinical Physics and Bioengineering, Beatson West of Scotland Cancer Centre, Glasgow, UK.
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Nikolaou K, Cyran CC, Lauber K, Reiser MF, Clevert DA. [Preclinical imaging in animal models of radiation therapy]. Radiologe 2012; 52:252-62. [PMID: 22382437 DOI: 10.1007/s00117-011-2194-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
CLINICAL/METHODICAL ISSUE Modern radiotherapy benefits from precise and targeted diagnostic and pretherapeutic imaging. STANDARD RADIOLOGICAL METHODS Standard imaging modalities, such as computed tomography (CT) offer high morphological detail but only limited functional information on tumors. METHODICAL INNOVATIONS Novel functional and molecular imaging modalities provide biological information about tumors in addition to detailed morphological information. PERFORMANCE Perfusion magnetic resonance imaging (MRI) CT or ultrasound-based perfusion imaging as well as hybrid modalities, such as positron emission tomography (PET) CT or MRI-PET have the potential to identify and precisely delineate viable and/or perfused tumor areas, enabling optimization of targeted radiotherapy. Functional information on tissue microcirculation and/or glucose metabolism allow a more precise definition and treatment of tumors while reducing the radiation dose and sparing the surrounding healthy tissue. ACHIEVEMENTS In the development of new imaging methods for planning individualized radiotherapy, preclinical imaging and research plays a pivotal role, as the value of multimodality imaging can only be assessed, tested and adequately developed in a preclinical setting, i.e. in animal tumor models. PRACTICAL RECOMMENDATIONS New functional imaging modalities will play an increasing role for the surveillance of early treatment response during radiation therapy and in the assessment of the potential value of new combination therapies (e.g. combining anti-angiogenic drugs with radiotherapy).
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Affiliation(s)
- K Nikolaou
- Institut für Klinische Radiologie, Klinikum der Ludwig-Maximilians-Universität, Campus Grosshadern, Marchioninistr. 15, 81377 München.
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Ho YW, Wong WKR, Yu SK, Lam WW, Geng H. Accuracy in contouring of small and low contrast lesions: comparison between diagnostic quality computed tomography scanner and computed tomography simulation scanner-A phantom study. Med Dosim 2012; 37:401-5. [PMID: 22626967 DOI: 10.1016/j.meddos.2012.03.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Revised: 02/27/2012] [Accepted: 03/15/2012] [Indexed: 11/28/2022]
Abstract
To evaluate the accuracy in detection of small and low-contrast regions using a high-definition diagnostic computed tomography (CT) scanner compared with a radiotherapy CT simulation scanner. A custom-made phantom with cylindrical holes of diameters ranging from 2-9 mm was filled with 9 different concentrations of contrast solution. The phantom was scanned using a 16-slice multidetector CT simulation scanner (LightSpeed RT16, General Electric Healthcare, Milwaukee, WI) and a 64-slice high-definition diagnostic CT scanner (Discovery CT750 HD, General Electric Healthcare). The low-contrast regions of interest (ROIs) were delineated automatically upon their full width at half maximum of the CT number profile in Hounsfield units on a treatment planning workstation. Two conformal indexes, CI(in), and CI(out), were calculated to represent the percentage errors of underestimation and overestimation in the automated contours compared with their actual sizes. Summarizing the conformal indexes of different sizes and contrast concentration, the means of CI(in) and CI(out) for the CT simulation scanner were 33.7% and 60.9%, respectively, and 10.5% and 41.5% were found for the diagnostic CT scanner. The mean differences between the 2 scanners' CI(in) and CI(out) were shown to be significant with p < 0.001. A descending trend of the index values was observed as the ROI size increases for both scanners, which indicates an improved accuracy when the ROI size increases, whereas no observable trend was found in the contouring accuracy with respect to the contrast levels in this study. Images acquired by the diagnostic CT scanner allow higher accuracy on size estimation compared with the CT simulation scanner in this study. We recommend using a diagnostic CT scanner to scan patients with small lesions (<1 cm in diameter) for radiotherapy treatment planning, especially for those pending for stereotactic radiosurgery in which accurate delineation of small-sized, low-contrast regions is important for dose calculation.
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Affiliation(s)
- Yick Wing Ho
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Hong Kong.
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Dean CJ, Sykes JR, Cooper RA, Hatfield P, Carey B, Swift S, Bacon SE, Thwaites D, Sebag-Montefiore D, Morgan AM. An evaluation of four CT-MRI co-registration techniques for radiotherapy treatment planning of prone rectal cancer patients. Br J Radiol 2012; 85:61-8. [PMID: 22190750 DOI: 10.1259/bjr/11855927] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
OBJECTIVES MRI is the preferred staging modality for rectal carcinoma patients. This work assesses the CT-MRI co-registration accuracy of four commercial rigid-body techniques for external beam radiotherapy treatment planning for patients treated in the prone position without fiducial markers. METHODS 17 patients with biopsy-proven rectal carcinoma were scanned with CT and MRI in the prone position without the use of fiducial markers. A reference co-registration was performed by consensus of a radiologist and two physicists. This was compared with two automated and two manual techniques on two separate treatment planning systems. Accuracy and reproducibility were analysed using a measure of target registration error (TRE) that was based on the average distance of the mis-registration between vertices of the clinically relevant gross tumour volume as delineated on the CT image. RESULTS An automated technique achieved the greatest accuracy, with a TRE of 2.3 mm. Both automated techniques demonstrated perfect reproducibility and were significantly faster than their manual counterparts. There was a significant difference in TRE between registrations performed on the two planning systems, but there were no significant differences between the manual and automated techniques. CONCLUSION For patients with rectal cancer, MRI acquired in the prone treatment position without fiducial markers can be accurately registered with planning CT. An automated registration technique offered a fast and accurate solution with associated uncertainties within acceptable treatment planning limits.
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Affiliation(s)
- C J Dean
- Department of Medical Physics, St James's Institute of Oncology, Leeds, UK.
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Alexander EJ, Harris VA, Sohaib A, Dearnaley D. Reducing the side effects of external beam radiotherapy in prostate cancer: role of imaging techniques. ACTA ACUST UNITED AC 2012. [DOI: 10.2217/iim.11.65] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Dimopoulos JCA, Petrow P, Tanderup K, Petric P, Berger D, Kirisits C, Pedersen EM, van Limbergen E, Haie-Meder C, Pötter R. Recommendations from Gynaecological (GYN) GEC-ESTRO Working Group (IV): Basic principles and parameters for MR imaging within the frame of image based adaptive cervix cancer brachytherapy. Radiother Oncol 2012; 103:113-22. [PMID: 22296748 PMCID: PMC3336085 DOI: 10.1016/j.radonc.2011.12.024] [Citation(s) in RCA: 317] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Revised: 11/28/2011] [Accepted: 12/28/2011] [Indexed: 12/18/2022]
Abstract
The GYN GEC-ESTRO working group issued three parts of recommendations and highlighted the pivotal role of MRI for the successful implementation of 3D image-based cervical cancer brachytherapy (BT). The main advantage of MRI as an imaging modality is its superior soft tissue depiction quality. To exploit the full potential of MRI for the better ability of the radiation oncologist to make the appropriate choice for the BT application technique and to accurately define the target volumes and the organs at risk, certain MR imaging criteria have to be fulfilled. Technical requirements, patient preparation, as well as image acquisition protocols have to be tailored to the needs of 3D image-based BT. The present recommendation is focused on the general principles of MR imaging for 3D image-based BT. Methods and parameters have been developed and progressively validated from clinical experience from different institutions (IGR, Universities of Vienna, Leuven, Aarhus and Ljubljana) and successfully applied during expert meetings, contouring workshops, as well as within clinical and interobserver studies. It is useful to perform pelvic MRI scanning prior to radiotherapy (“Pre-RT-MRI examination”) and at the time of BT (“BT MRI examination”) with one MR imager. Both low and high-field imagers, as well as both open and close magnet configurations conform to the requirements of 3D image-based cervical cancer BT. Multiplanar (transversal, sagittal, coronal and oblique image orientation) T2-weighted images obtained with pelvic surface coils are considered as the golden standard for visualisation of the tumour and the critical organs. The use of complementary MRI sequences (e.g. contrast-enhanced T1-weighted or 3D isotropic MRI sequences) is optional. Patient preparation has to be adapted to the needs of BT intervention and MR imaging. It is recommended to visualise and interpret the MR images on dedicated DICOM-viewer workstations, which should also assist the contouring procedure. Choice of imaging parameters and BT equipment is made after taking into account aspects of interaction between imaging and applicator reconstruction, as well as those between imaging, geometry and dose calculation. In a prospective clinical context, to implement 3D image-based cervical cancer brachytherapy and to take advantage of its full potential, it is essential to successfully meet the MR imaging criteria described in the present recommendations of the GYN GEC-ESTRO working group.
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Gwynne S, Mukherjee S, Webster R, Spezi E, Staffurth J, Coles B, Adams R. Imaging for target volume delineation in rectal cancer radiotherapy--a systematic review. Clin Oncol (R Coll Radiol) 2011; 24:52-63. [PMID: 22035634 DOI: 10.1016/j.clon.2011.10.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 09/15/2011] [Accepted: 09/19/2011] [Indexed: 01/09/2023]
Abstract
The global move towards more conformal radiotherapy for rectal cancer requires better imaging modalities that both visualise the disease accurately and are reproducible; to reduce interobserver variation. This review explores the advances in imaging modalities used in target volume delineation, with a view to make recommendations for current clinical practice and to propose future directions for research. A systematic review was conducted using MEDLINE and EMBASE. Articles considered relevant by the authors were included. Planning with orthogonal films is being replaced by computed tomography (CT) simulation. This is now considered the 'gold standard' and allows conformal three-dimensional planning. Magnetic resonance imaging (MRI) has been shown to overcome some of the limitations of CT and can be used either as a diagnostic image to visually aid planning, or as a 'planning' MRI carried out in the treatment position and co-registered with the planning CT. The latter approach has been shown to change the treated volumes compared with CT and in prostate cancer patients has been shown to reduce interobserver variation. There are remaining issues with four-dimensional motion that are yet to be fully appreciated or overcome. 2-[18F] fluoro-2-deoxy-d-glucose positron emission tomography/CT co-registered with planning CT results in smaller volumes than CT alone and also reduces interobserver variation, but requires further validation before routine implementation. Experimental work utilising novel positron emission tomography tracers and diffusion-weighted MRI shows promise and requires further evaluation. Rigorous quality assurance is important with processing of newer imaging modalities. Further work needs to be conducted into both interobserver variation and the formal evaluation of the clinical benefits of newer imaging modalities. Developments in image-guided radiotherapy are also required to ensure that improvements in target definition at the planning stage are reproducible throughout treatment.
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Affiliation(s)
- S Gwynne
- Department of Clinical Oncology, Velindre Cancer Centre, Cardiff, UK.
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Massabeau C, Marchand V, Zefkili S, Servois V, Campana F, Giraud P. Early experience of helical tomotherapy for hepatobiliary radiotherapy. Case Reports Hepatol 2011; 2011:545267. [PMID: 25954545 PMCID: PMC4411892 DOI: 10.1155/2011/545267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Accepted: 05/14/2011] [Indexed: 11/17/2022] Open
Abstract
Helical tomotherapy (HT), an image-guided, intensity-modulated, radiation therapy technique, allows for precise targeting while sparing normal tissues. We retrospectively assessed the feasibility and tolerance of the hepatobiliary HT in 9 patients. A total dose of 54 to 60 Gy was prescribed (1.8 or 2 Gy per fraction) with concurrent capecitabine for 7 patients. There were 1 hepatocarcinoma, 3 cholangiocarcinoma, 4 liver metastatic patients, and 1 pancreatic adenocarcinoma. All but one patient received previous therapies (chemotherapy, liver radiofrequency, and/or surgery). The median doses delivered to the normal liver and to the right kidney were 15.7 Gy and 4.4 Gy, respectively, below the recommended limits for all patients. Most of the treatment-related adverse events were transient and mild in severity. With a median followup of 12 months, no significant late toxicity was noted. Our results suggested that HT could be safely incorporated into the multidisciplinary treatment of hepatobiliary or pancreatic malignant disease.
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Affiliation(s)
- Carole Massabeau
- Department of Radiation Oncology and Medical Physics, Institut Curie, 75005 Paris, France
- Department of Radiation Oncology, Institut Claudius Regaud, 31052 Toulouse, France
| | - Virginie Marchand
- Department of Radiation Oncology and Medical Physics, Institut Curie, 75005 Paris, France
| | - Sofia Zefkili
- Department of Radiation Oncology and Medical Physics, Institut Curie, 75005 Paris, France
| | - Vincent Servois
- Department of Radiology, Institut Curie, 75005 Paris, France
| | - François Campana
- Department of Radiation Oncology and Medical Physics, Institut Curie, 75005 Paris, France
| | - Philippe Giraud
- Department of Radiation Oncology and Medical Physics, Institut Curie, 75005 Paris, France
- Department of Radiation Oncology, European Georges Pompidou Hospital, 75015 Paris, Paris Descartes University, 75005 Paris, France
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Das SK, Ten Haken RK. Functional and molecular image guidance in radiotherapy treatment planning optimization. Semin Radiat Oncol 2011; 21:111-8. [PMID: 21356479 DOI: 10.1016/j.semradonc.2010.10.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Functional and molecular imaging techniques are increasingly being developed and used to quantitatively map the spatial distribution of parameters, such as metabolism, proliferation, hypoxia, perfusion, and ventilation, onto anatomically imaged normal organs and tumor. In radiotherapy optimization, these imaging modalities offer the promise of increased dose sparing to high-functioning subregions of normal organs or dose escalation to selected subregions of the tumor as well as the potential to adapt radiotherapy to functional changes that occur during the course of treatment. The practical use of functional/molecular imaging in radiotherapy optimization must take into cautious consideration several factors whose influences are still not clearly quantified or well understood including patient positioning differences between the planning computed tomography and functional/molecular imaging sessions, image reconstruction parameters and techniques, image registration, target/normal organ functional segmentation, the relationship governing the dose escalation/sparing warranted by the functional/molecular image intensity map, and radiotherapy-induced changes in the image intensity map over the course of treatment. The clinical benefit of functional/molecular image guidance in the form of improved local control or decreased normal organ toxicity has yet to be shown and awaits prospective clinical trials addressing this issue.
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Affiliation(s)
- Shiva K Das
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
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Njeh CF. Tumor delineation: The weakest link in the search for accuracy in radiotherapy. J Med Phys 2011; 33:136-40. [PMID: 19893706 PMCID: PMC2772050 DOI: 10.4103/0971-6203.44472] [Citation(s) in RCA: 177] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2008] [Accepted: 10/22/2008] [Indexed: 11/04/2022] Open
Abstract
Radiotherapy is one of the most effective modalities for the treatment of cancer. However, there is a high degree of uncertainty associated with the target volume of most cancer sites. The sources of these uncertainties include, but are not limited to, the motion of the target, patient setup errors, patient movements, and the delineation of the target volume. Recently, many imaging techniques have been introduced to track the motion of tumors. The treatment delivery using these techniques is collectively called image-guided radiation therapy (IGRT). Ultimately, IGRT is only as good as the accuracy with which the target is known. There are reports of interobserver variability in tumor delineation across anatomical sites, but the widest ranges of variations have been reported for the delineation of head and neck tumors as well as esophageal and lung carcinomas. Significant interobserver variability in target delineation can be attributed to many factors including the impact of imaging and the influence of the observer (specialty, training, and personal bias). The visibility of the target can be greatly improved with the use of multimodality imaging by co-registration of CT with a second modality such as magnetic resonance imaging (MRI) and/or positron emission tomography. Also, continuous education, training, and cross-collaboration of the radiation oncologist with other specialties can reduce the degree of variability in tumor delineation.
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Affiliation(s)
- C F Njeh
- Tyler Cancer Center (US oncology), Radiation Oncology Department, 910 East Houston Street, Tyler, Texas, 75702, USA
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Arimura H, Magome T, Anai S, Shioyama Y, Nakamura K. [Medical imaging processing and evaluation in radiation therapy]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2011; 67:76-83. [PMID: 21301175 DOI: 10.6009/jjrt.67.76] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
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Tracer kinetic modelling of tumour angiogenesis based on dynamic contrast-enhanced CT and MRI measurements. Eur J Nucl Med Mol Imaging 2010; 37 Suppl 1:S30-51. [PMID: 20503049 DOI: 10.1007/s00259-010-1448-7] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
PURPOSE Technical developments in both magnetic resonance imaging (MRI) and computed tomography (CT) have helped to reduce scan times and expedited the development of dynamic contrast-enhanced (DCE) imaging techniques. Since the temporal change of the image signal following the administration of a diffusible, extracellular contrast agent (CA) is related to the local blood supply and the extravasation of the CA into the interstitial space, DCE imaging can be used to assess tissue microvasculature and microcirculation. It is the aim of this review to summarize the biophysical and tracer kinetic principles underlying this emerging imaging technique offering great potential for non-invasive characterization of tumour angiogenesis. METHODS In the first part, the relevant contrast mechanisms are presented that form the basis to relate signal variations measured by serial CT and MRI to local tissue concentrations of the administered CA. In the second part, the concepts most widely used for tracer kinetic modelling of concentration-time courses derived from measured DCE image data sets are described in a consistent and unified manner to highlight their particular structure and assumptions as well as the relationships among them. Finally, the concepts presented are exemplified by the analysis of representative DCE data as well as discussed with respect to present and future applications in cancer diagnosis and therapy. RESULTS Depending on the specific protocol used for the acquisition of DCE image data and the particular model applied for tracer kinetic analysis of the derived concentration-time courses, different aspects of tumour angiogenesis can be quantified in terms of well-defined physiological tissue parameters. CONCLUSIONS DCE imaging offers promising prospects for improved tumour diagnosis, individualization of cancer treatment as well as the evaluation of novel therapeutic concepts in preclinical and early-stage clinical trials.
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Tan J, Lim Joon D, Fitt G, Wada M, Lim Joon M, Mercuri A, Marr M, Chao M, Khoo V. The utility of multimodality imaging with CT and MRI in defining rectal tumour volumes for radiotherapy treatment planning: a pilot study. J Med Imaging Radiat Oncol 2010; 54:562-8. [DOI: 10.1111/j.1754-9485.2010.02212.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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Brunt J. Computed Tomography–Magnetic Resonance Image Registration in Radiotherapy Treatment Planning. Clin Oncol (R Coll Radiol) 2010; 22:688-97. [DOI: 10.1016/j.clon.2010.06.016] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Accepted: 06/28/2010] [Indexed: 11/25/2022]
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Abstract
This paper reviews the integration of imaging and radiation oncology, and discusses challenges and opportunities for improving the practice of radiation oncology with imaging. An inherent goal of radiation therapy is to deliver enough dose to the tumor to eradicate all cancer cells or to palliate symptoms, while avoiding normal tissue injury. Imaging for cancer diagnosis, staging, treatment planning, and radiation targeting has been integrated in various ways to improve the chance of this occurring. A large spectrum of imaging strategies and technologies has evolved in parallel to advances in radiation delivery. The types of imaging can be categorized into offline imaging (outside the treatment room) and online imaging (inside the treatment room, conventionally termed image-guided radiation therapy). The direct integration of images in the radiotherapy planning process (physically or computationally) often entails trade-offs in imaging performance. Although such compromises may be acceptable given specific clinical objectives, general requirements for imaging performance are expected to increase as paradigms for radiation delivery evolve to address underlying biology and adapt to radiation responses. This paper reviews the integration of imaging and radiation oncology, and discusses challenges and opportunities for improving the practice of radiation oncology with imaging.
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Affiliation(s)
- Laura A Dawson
- Department of Radiation Oncology, Princess Margaret Hospital, University of Toronto, Toronto, Ontario, Canada.
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Patel C, Goldstone A, Chowdhury F, Scarsbrook A. FDG PET/CT in oncology: “raising the bar”. Clin Radiol 2010; 65:522-35. [DOI: 10.1016/j.crad.2010.01.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Revised: 12/23/2009] [Accepted: 01/05/2010] [Indexed: 10/19/2022]
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Superparamagnetic iron oxide nanoparticles: diagnostic magnetic resonance imaging and potential therapeutic applications in neurooncology and central nervous system inflammatory pathologies, a review. J Cereb Blood Flow Metab 2010; 30:15-35. [PMID: 19756021 PMCID: PMC2949106 DOI: 10.1038/jcbfm.2009.192] [Citation(s) in RCA: 305] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Superparamagnetic iron oxide nanoparticles have diverse diagnostic and potential therapeutic applications in the central nervous system (CNS). They are useful as magnetic resonance imaging (MRI) contrast agents to evaluate: areas of blood-brain barrier (BBB) dysfunction related to tumors and other neuroinflammatory pathologies, the cerebrovasculature using perfusion-weighted MRI sequences, and in vivo cellular tracking in CNS disease or injury. Novel, targeted, nanoparticle synthesis strategies will allow for a rapidly expanding range of applications in patients with brain tumors, cerebral ischemia or stroke, carotid atherosclerosis, multiple sclerosis, traumatic brain injury, and epilepsy. These strategies may ultimately improve disease detection, therapeutic monitoring, and treatment efficacy especially in the context of antiangiogenic chemotherapy and antiinflammatory medications. The purpose of this review is to outline the current status of superparamagnetic iron oxide nanoparticles in the context of biomedical nanotechnology as they apply to diagnostic MRI and potential therapeutic applications in neurooncology and other CNS inflammatory conditions.
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133
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Simpson DR, Lawson JD, Nath SK, Rose BS, Mundt AJ, Mell LK. Utilization of advanced imaging technologies for target delineation in radiation oncology. J Am Coll Radiol 2009; 6:876-83. [PMID: 19945044 DOI: 10.1016/j.jacr.2009.08.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2009] [Accepted: 08/03/2009] [Indexed: 11/26/2022]
Abstract
PURPOSE The aim of this study was to evaluate the utilization of advanced imaging technologies for target delineation among radiation oncologists in the United States. METHODS A random sample of 1,600 radiation oncologists was contacted by Internet, e-mail, and fax and questioned regarding the use of advanced imaging technologies, clinical applications, and future plans for use. Advanced imaging technologies were defined as any of the following that were directly incorporated into radiation therapy planning: MRI, PET, single-photon emission CT, 4-D CT, functional MRI, and MR spectroscopy. RESULTS Of 1,089 contactable physicians, 394 (36%) responded. Of respondents, 65% were in private practice and 35% were in academic practice. The proportion using any advanced imaging technology for target delineation was 95%. However, the majority reported only rare (in <25% of their patients; 46.6%) or infrequent (in 25%-50% of their patients; 26.0%) utilization. The most commonly used technologies were 2-[(18)F]fluoro-2-deoxyglucose PET (76%), MRI (72%), and 4-D CT (44%). The most common cancers treated using image-guided target delineation were those of the lung (83%), central nervous system (79%), and head and neck (79%). Among users of advanced imaging technologies, 66% planned to increase use; 30% of nonusers planned to adopt these technologies in the future. CONCLUSIONS Advanced imaging technologies are widely used by US radiation oncologists for target delineation. Although the majority of respondents used them in <50% of their patients, the frequency of utilization is expected to increase. Studies determining the optimal application of these technologies in radiation therapy planning are needed.
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Affiliation(s)
- Daniel R Simpson
- Department of Radiation Oncology and Center for Advanced Radiotherapy Technologies, Rebecca and John Moores Comprehensive Cancer Center, University of California, San Diego, La Jolla, California 92093-0843, USA
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134
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135
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Affiliation(s)
- V Khoo
- Royal Marsden NHS Foundation Trust Hospital & Institute of Cancer Research, Fulham Road, London
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136
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Jain TK, Foy SP, Erokwu B, Dimitrijevic S, Flask CA, Labhasetwar V. Magnetic resonance imaging of multifunctional pluronic stabilized iron-oxide nanoparticles in tumor-bearing mice. Biomaterials 2009; 30:6748-56. [PMID: 19765817 DOI: 10.1016/j.biomaterials.2009.08.042] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2009] [Accepted: 08/27/2009] [Indexed: 01/08/2023]
Abstract
We are investigating the magnetic resonance imaging characteristics of magnetic nanoparticles (MNPs) that consist of an iron-oxide magnetic core coated with oleic acid (OA), then stabilized with a pluronic or tetronic block copolymer. Since pluronics and tetronics vary structurally, and also in the ratio of hydrophobic (poly[propylene oxide]) and hydrophilic (poly[ethylene oxide]) segments in the polymer chain and in molecular weight, it was hypothesized that their anchoring to the OA coating around the magnetic core could significantly influence the physical properties of MNPs, their interactions with biological environment following intravenous administration, and ability to localize to tumors. The amount of block copolymer associated with MNPs was seen to depend upon their molecular structures and influence the characteristics of MNPs. Pluronic F127-modified MNPs demonstrated sustained and enhanced contrast in the whole tumor, whereas that of Feridex IV was transient and confined to the tumor periphery. In conclusion, our pluronic F127-coated MNPs, which can also be loaded with anticancer agents for drug delivery, can be developed as an effective cancer theranostic agent, i.e. an agent with combined drug delivery and imaging properties.
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Affiliation(s)
- Tapan K Jain
- Department of Biomedical Engineering/ND20, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue Cleveland, OH 44195, USA
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137
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Hanvey S, Glegg M, Foster J. Magnetic resonance imaging for radiotherapy planning of brain cancer patients using immobilization and surface coils. Phys Med Biol 2009; 54:5381-94. [DOI: 10.1088/0031-9155/54/18/002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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138
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Medical Imaging Modalities in Radiotherapy. Radiat Oncol 2008. [DOI: 10.1007/978-3-540-77385-6_45] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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139
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Twenty-year review of radiotherapy for vaginal cancer: An institutional experience. Gynecol Oncol 2008; 111:298-306. [DOI: 10.1016/j.ygyno.2008.07.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Revised: 07/06/2008] [Accepted: 07/08/2008] [Indexed: 11/21/2022]
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140
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Kader HA, Truong PT, Pai R, Panades M, Jones S, Ansbacher W, Olivotto IA. When Is CT-Based Postoperative Seroma Most Useful to Plan Partial Breast Radiotherapy? Evaluation of Clinical Factors Affecting Seroma Volume and Clarity. Int J Radiat Oncol Biol Phys 2008; 72:1064-9. [PMID: 18411005 DOI: 10.1016/j.ijrobp.2008.02.049] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2008] [Revised: 02/14/2008] [Accepted: 02/15/2008] [Indexed: 10/22/2022]
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141
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Abstract
The recent wave of enthusiasm for image guidance in radiation therapy is largely due to the advent of on-line imaging devices. The current narrow definition of image-guided radiotherapy (IGRT), in fact, essentially connotes the use of near real-time imaging during treatment delivery to reduce uncertainties in target position and should therefore be termed IGRT-D. However, a broader (and more appropriate) context of image-guidance should include: (1) detection and diagnosis, (2) delineation of target and organs at risk, (3) determining biological attributes, (4) dose distribution design, (5) dose delivery assurance and (6) deciphering treatment response through imaging i.e. the 6 D's of IGRT. Strategies to advance these areas will be discussed.
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142
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Wang C, Chao M, Lee L, Xing L. MRI-based Treatment Planning with Electron Density Information Mapped from CT Images: A Preliminary Study. Technol Cancer Res Treat 2008; 7:341-8. [DOI: 10.1177/153303460800700501] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Nowadays magnetic resonance imaging (MRI) has been profoundly used in radiotherapy (RT) planning to aid the contouring of targets and critical organs in brain and intracranial cases, which is attributable to its excellent soft tissue contrast and multi-planar imaging capability. However, the lack of electron density information in MRI, together with the image distortion issues, precludes its use as the sole image set for RT planning and dose calculation. The purpose of this preliminary study is to probe the feasibility and evaluate an MRI-based radiation dose calculation process by providing MR images the necessary electron density (ED) information from a patient's readily available diagnostic/staging computed tomography (CT) images using an image registration model. To evaluate the dosimetric accuracy of the proposed approach, three brain and three intracranial cases were selected retrospectively for this study. For each patient, the MR images were registered to the CT images, and the ED information was then mapped onto the MR images by in-house developed software generating a modified set of MR images. Another set of MR images with voxel values assigned with the density of water was also generated. The original intensity modulated radiation treatment (IMRT) plan was then applied to the two sets of MR images and the doses were calculated. The dose distributions from the MRI-based calculations were compared to that of the original CT-based calculation. In all cases, the MRI-based calculations with mapped ED yielded dose values very close (within 2%) to that of the CT-based calculations. The MRI-based calculations with voxel values assigned with water density indicated a dosimetric error of 3–5%, depending on the treatment site. The present approach offers a means of utilizing MR images for accurate dose calculation and affords a potential to eliminate the redundant simulation CT by planning a patient's treatment with only simulation MRI and any available diagnostic/staging CT data.
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Affiliation(s)
- C. Wang
- Department of Radiation Oncology, Stanford, University School of Medicine, Stanford, CA 94305, USA
| | - M. Chao
- Department of Radiation Oncology, Stanford, University School of Medicine, Stanford, CA 94305, USA
| | - L. Lee
- Department of Radiation Oncology, Stanford, University School of Medicine, Stanford, CA 94305, USA
| | - L. Xing
- Department of Radiation Oncology, Stanford, University School of Medicine, Stanford, CA 94305, USA
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Abstract
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 scans is taken on different days. Both allow planning to account for variability intrinsic to the patient. Treatment verification has been carried out using a variety of technologies including: MV portal imaging, kV portal/fluoroscopy, MVCT, conebeam kVCT, ultrasound and optical surface imaging. The various methods have their pros and cons. The four x-ray methods involve an extra radiation dose to normal tissue. The portal methods may not generally be used to visualize soft tissue, consequently they are often used in conjunction with implanted fiducial markers. The two CT-based methods allow measurement of inter-fraction variation only. Ultrasound allows soft-tissue measurement with zero dose but requires skilled interpretation, and there is evidence of systematic differences between ultrasound and other data sources, perhaps due to the effects of the probe pressure. Optical imaging also involves zero dose but requires good correlation between the target and the external measurement and thus is often used in conjunction with an x-ray method. The use of anatomical imaging in radiotherapy allows treatment uncertainties to be determined. These include errors between the mean position at treatment and that at planning (the systematic error) and the day-to-day variation in treatment set-up (the random error). Positional variations may also be categorized in terms of inter- and intra-fraction errors. Various empirical treatment margin formulae and intervention approaches exist to determine the optimum strategies for treatment in the presence of these known errors. Other methods exist to try to minimize error margins drastically including the currently available breath-hold techniques and the tracking methods which are largely in development. This paper will review anatomical imaging techniques in radiotherapy and how they are used to boost the therapeutic benefit of the treatment.
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Affiliation(s)
- Philip M Evans
- Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Downs Road, Sutton, Surrey SM2 5PT, UK.
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144
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Mah D, Chen CC. Image guidance in radiation oncology treatment planning: the role of imaging technologies on the planning process. Semin Nucl Med 2008; 38:114-8. [PMID: 18243846 DOI: 10.1053/j.semnuclmed.2007.11.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Radiation therapy has evolved from 2-dimensional (2D) to 3-dimensional (3D) treatments and, more recently, to intensity-modulated radiation therapy and image-guided radiation therapy. Improvements in imaging have enabled improvements in targeting and treatment. As computer-processing power has improved during the past few decades, it has facilitated developments in both imaging and treatment. The historical role of imaging from 2D to image-guided radiation therapy is reviewed here. Examples of imaging technologies such as positron emission tomography and magnetic resonance imaging are provided. The role of these imaging technologies, organ motion management approaches and their potential impacts on radiation therapy are described.
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Affiliation(s)
- Dennis Mah
- Department of Radiation Oncology, Montefiore Medical Center, Bronx, NY 10467, USA.
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145
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Yorke ED, Keall P, Verhaegen F. Anniversary Paper: Role of medical physicists and the AAPM in improving geometric aspects of treatment accuracy and precision. Med Phys 2008; 35:828-39. [DOI: 10.1118/1.2836420] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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146
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Khoo VS, Dearnaley DP. Question of dose, fractionation and technique: ingredients for testing hypofractionation in prostate cancer--the CHHiP trial. Clin Oncol (R Coll Radiol) 2007; 20:12-4. [PMID: 18036791 DOI: 10.1016/j.clon.2007.10.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Revised: 09/30/2007] [Accepted: 10/16/2007] [Indexed: 10/22/2022]
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147
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Herneth AM, Ringl H, Memarsadeghi M, Fueger B, Friedrich KM, Krestan C, Imhof H. Diffusion weighted imaging in osteoradiology. Top Magn Reson Imaging 2007; 18:203-12. [PMID: 17762384 DOI: 10.1097/rmr.0b013e3180cac61d] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Diffusion weighted imaging gained attention as an imaging modality, which provides information on the microstructure of a tissue, which can be used for tissue characterization. This is of importance in patients where other diagnostic tools provide equivocal or unspecific information. In addition quantitative diffusion measurements provide objective parameters for unbiased comparison of treatment response, which is mandatory for therapy monitoring. Technical restriction limited the use of Diffusion Weighted Imaging to the brain. However, with the improvement in scanner technology and the availability of new MR sequences investigation of the Muskulo Skeletal System was made possible. We describe the potential of Diffusion Weighted Imaging as a non-invasive technique to evaluate pathological, inflammatory and physiological processes in osteoradiology.
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Affiliation(s)
- Andreas M Herneth
- Departmentsof Radiology, Medical University of Vienna, Vienna, Austria.
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148
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Lecchi M, Fossati P, Elisei F, Orecchia R, Lucignani G. Current concepts on imaging in radiotherapy. Eur J Nucl Med Mol Imaging 2007; 35:821-37. [PMID: 17972074 DOI: 10.1007/s00259-007-0631-y] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2007] [Accepted: 10/02/2007] [Indexed: 11/29/2022]
Abstract
New high-precision radiotherapy (RT) techniques, such as intensity-modulated radiation therapy (IMRT) or hadrontherapy, allow better dose distribution within the target and spare a larger portion of normal tissue than conventional RT. These techniques require accurate tumour volume delineation and intrinsic characterization, as well as verification of target localisation and monitoring of organ motion and response assessment during treatment. These tasks are strongly dependent on imaging technologies. Among these, computed tomography (CT), magnetic resonance imaging (MRI), ultrasonography (US) and positron emission tomography (PET) have been applied in high-precision RT. For tumour volume delineation and characterization, PET has brought an additional dimension to the management of cancer patients by allowing the incorporation of crucial functional and molecular images in RT treatment planning, i.e. direct evaluation of tumour metabolism, cell proliferation, apoptosis, hypoxia and angiogenesis. The combination of PET and CT in a single imaging system (PET/CT) to obtain a fused anatomical and functional dataset is now emerging as a promising tool in radiotherapy departments for delineation of tumour volumes and optimization of treatment plans. Another exciting new area is image-guided radiotherapy (IGRT), which focuses on the potential benefit of advanced imaging and image registration to improve precision, daily target localization and monitoring during treatment, thus reducing morbidity and potentially allowing the safe delivery of higher doses. The variety of IGRT systems is rapidly expanding, including cone beam CT and US. This article examines the increasing role of imaging techniques in the entire process of high-precision radiotherapy.
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Affiliation(s)
- Michela Lecchi
- Institute of Radiological Sciences, University of Milan, Milan, Italy
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