Use of PET and Other Functional Imaging to Guide Target Delineation in Radiation Oncology
Molecular and functional imaging is increasingly being used to guide radiotherapy (RT) management and target delineation. This review summarizes existing data in several disease sites of various functional imaging modalities, chiefly positron emission tomography/computed tomography (PET/CT), with respect to RT target definition and management. For gliomas, differentiation between postoperative changes and viable tumor is discussed, as well as focal dose escalation and reirradiation. Head and neck neoplasms may also benefit from precise PET/CT-based target delineation, especially for cancers of unknown primary; focal dose e...
Source: Seminars in Radiation Oncology - June 1, 2018 Category: Cancer & Oncology Authors: Vivek Verma, J. Isabelle Choi, Amit Sawant, Rao P. Gullapalli, Wengen Chen, Abass Alavi, Charles B. Simone Source Type: research
Magnetic Resonance Imaging for Target Delineation and Daily Treatment Modification
Magnetic resonance (MR) imaging has become a prevalent modality in radiation oncology owing to its excellent soft-tissue contrast and ability to provide functional information. Recent technological developments have combined MR imaging with treatment delivery systems, to provide in-room MR guidance for patient setup and treatment delivery. Availability of in-room MR imaging enables direct visualization of soft-tissue targets and nearby organs at risk, thus providing a platform for fast and accurate target and organs at risk delineation for plan adaptation and target tracking during treatment. (Source: Seminars in Radiation Oncology)
Source: Seminars in Radiation Oncology - June 1, 2018 Category: Cancer & Oncology Authors: Rojano Kashani, Jeffrey R. Olsen Source Type: research
The Role of Optical Surface Imaging Systems in Radiation Therapy
Optical surface imaging is a nonradiographic, noninvasive technology for continuous localization of patients during radiation therapy. Surface-guided radiation therapy (SGRT) has been applied to many treatment sites including breast, intracranial, head and neck, and extremities. SGRT enables a reduction of initial setup variability, provides verification of immobilization continuously during treatment including at noncoplanar linac gantry angles, and provides dynamic surface information for use in gated and breath-hold treatment techniques, all of which can permit reductions in the margins required to account for target lo...
Source: Seminars in Radiation Oncology - June 1, 2018 Category: Cancer & Oncology Authors: Jeremy D.P. Hoisak, Todd Pawlicki Source Type: research
Accounting for, Mitigating, and Choice of Margins for Moving Tumors
This article reviews the use of advanced and functional imaging to guide target delineation, considerations for margin selections, technique for accounting for and mitigation of tumor motion in treatment planning and delivery, and motion management in radiation therapy. (Source: Seminars in Radiation Oncology)
Source: Seminars in Radiation Oncology - June 1, 2018 Category: Cancer & Oncology Authors: Heng Li, Joe Y. Chang Source Type: research
The Practicality of ICRU and Considerations for Future ICRU Definitions
The International Commission on Radiation Units and Measurements (ICRU) volumes are standardized volume definitions used in radiation oncology practice that have evolved over time to account for advancements in technology and radiation planning. The current definitions have strengths but also practical limitations. The main limitation is related to the process of accounting for tumor motion during treatment. As radiotherapeutic techniques become more precise, motion interplay effects and anatomical changes during treatment must be taken into account to ensure accurate and safe delivery of treatment. (Source: Seminars in Radiation Oncology)
Source: Seminars in Radiation Oncology - June 1, 2018 Category: Cancer & Oncology Authors: Annemarie Shepherd, Sara St. James, Ramesh Rengan Source Type: research
Stereotactic Ablative Radiotherapy Uncertainties: Delineation, Setup and Motion
Stereotactic ablative radiotherapy (SAbR), also known as stereotactic body radiation therapy, is biologically distinct from conventionally fractionated radiotherapy in that it is ablative, causing functional incapacitation of targeted tissue including margins added to avoid errors. In striking contrast, small 1.8-2Gy daily doses associated with historical fractionated radiotherapy cause more modest injury more likely to be repaired by normal tissue than tumor. Strategic plans to deal with uncertainties in tumor location, motion during treatment, dose deposition and heterogeneity effects, and tolerance require a novel appro...
Source: Seminars in Radiation Oncology - June 1, 2018 Category: Cancer & Oncology Authors: Ming Yang, Robert Timmerman Source Type: research
How Histopathologic Tumor Extent and Patterns of Recurrence Data Inform the Development of Radiation Therapy Treatment Volumes in Solid Malignancies
The ability to deliver highly conformal radiation therapy using intensity-modulated radiation therapy and particle therapy provides for new opportunities to improve patient outcomes by reducing treatment-related morbidities following radiation therapy. By reducing the volume of normal tissue exposed to radiation therapy (RT), while also allowing for the opportunity to escalate the dose of RT delivered to the tumor, use of conformal RT delivery should also provide the possibility of expanding the therapeutic index of radiotherapy. (Source: Seminars in Radiation Oncology)
Source: Seminars in Radiation Oncology - June 1, 2018 Category: Cancer & Oncology Authors: Arpit Chhabra, Craig Schneider, Mudit Chowdhary, Tejan P. Diwanji, Pranshu Mohindra, Mark V. Mishra Source Type: research
Current State of Image Guidance in Radiation Oncology: Implications for PTV Margin Expansion and Adaptive Therapy
Image guidance technology has evolved and seen widespread application in the past several decades. Advancements in the diagnostic imaging field have found new applications in radiation oncology and promoted the development of therapeutic devices with advanced imaging capabilities. A recent example is the development of linear accelerators that offer magnetic resonance imaging for real-time imaging and online adaptive planning. Volumetric imaging, in particular, offers more precise localization of soft tissue targets and critical organs which reduces setup uncertainty and permit the use of smaller setup margins. (Source: Se...
Source: Seminars in Radiation Oncology - June 1, 2018 Category: Cancer & Oncology Authors: Wei Zou, Lei Dong, Boon-Keng Kevin Teo Source Type: research
Concepts of PTV and Robustness in Passively Scattered and Pencil Beam Scanning Proton Therapy
Concepts of planning target volume and plan robustness in proton therapy are described. Implementation of these concepts into treatment planning is described. Proton plan sensitivity and interfractional and intrafractional anatomical variation are also discussed. (Source: Seminars in Radiation Oncology)
Source: Seminars in Radiation Oncology - June 1, 2018 Category: Cancer & Oncology Authors: Katja Langen, Mingyao Zhu Source Type: research
Relative Biological Effectiveness Uncertainties and Implications for Beam Arrangements and Dose Constraints in Proton Therapy
This article provides a brief review on the principles and individual factors contributing to RBE uncertainties, with emphasis on clinical practice. (Source: Seminars in Radiation Oncology)
Source: Seminars in Radiation Oncology - June 1, 2018 Category: Cancer & Oncology Authors: Harald Paganetti, Drosoula Giantsoudi Source Type: research
Margins and Uncertainties in Radiation Oncology
This issue of Seminars in Radiation Oncology focuses on margins, uncertainties, and errors in radiation oncology. This is the first focused issue of this journal to highlight this important and clinically practical topic. As radiation technology has advanced and treatment planning and delivery have become progressively more precise, these uncertainties and the need to understand the optimal margins required for radiotherapy delivery have become much more critical. (Source: Seminars in Radiation Oncology)
Source: Seminars in Radiation Oncology - June 1, 2018 Category: Cancer & Oncology Authors: Charles B. Simone, Amit Sawant Source Type: research
Protons vs Photons for Brain and Skull Base Tumors
The physical characteristics of proton therapy result in steeper dose gradients and superior dose conformality compared to photon therapy. These properties render proton therapy ideal for skull base tumors requiring dose escalation for optimal tumor control, and may also be beneficial for brain tumors as a means of mitigating radiation-related adverse effects. This review summarizes the literature regarding the role of proton therapy compared to photon therapy in the treatment of adult brain and skull base tumors. (Source: Seminars in Radiation Oncology)
Source: Seminars in Radiation Oncology - April 1, 2018 Category: Cancer & Oncology Authors: Safia K. Ahmed, Paul D. Brown, Robert L. Foote Source Type: research
Does Proton Therapy Offer Demonstrable Clinical Advantages for Treating Thoracic Tumors?
The finite range of proton beams in tissues offers unique dosimetric advantages that theoretically allow dose to the target to be escalated while minimizing exposure of surrounding tissues and thus minimizing radiation-induced toxicity. This theoretical advantage has led to widespread adoption of proton therapy around the world for a wide variety of tumors at different anatomical sites. Many treatment-planning comparisons have shown that proton therapy has substantial dosimetric advantages over conventional radiotherapy. (Source: Seminars in Radiation Oncology)
Source: Seminars in Radiation Oncology - April 1, 2018 Category: Cancer & Oncology Authors: Zhongxing Liao, Saumil J. Gandhi, Steven H. Lin, Jeffrey Bradley Source Type: research
Finding Value for Protons: The Case of Prostate Cancer?
The standard radiotherapy treatment for prostate cancer is intensity-modulated radiotherapy (IMRT). An alternative option is proton beam therapy (PBT). PBT is a safe and effective treatment, but does it add value over IMRT? We explore this controversial question by examining the available dosimetric and clinical evidence. (Source: Seminars in Radiation Oncology)
Source: Seminars in Radiation Oncology - April 1, 2018 Category: Cancer & Oncology Authors: Eric Ojerholm, Justin E. Bekelman Source Type: research
Heavy Charged Particles: Does Improved Precision and Higher Biological Effectiveness Translate to Better Outcome in Patients?
Protons are the most common charged particles used in oncology. Acceleration of heavier ions requires larger accelerators and is more expensive, yet heavy nuclei share the same advantageous dose-depth profile characteristics of protons and have potential additional advantages. These advantages are related to the physical characteristics of the beam, owing to reduced lateral scattering and sharper lateral penumbra. In addition, heavy ions produce an increased biological response. In fact, in the target region heavy ions behave as densely ionizing radiation, which produce distinct biological effects compared to sparsely ioni...
Source: Seminars in Radiation Oncology - April 1, 2018 Category: Cancer & Oncology Authors: Marco Durante, J ürgen Debus Source Type: research
