Intensity modulated radiotherapy (IMRT)—an introduction (original) (raw)
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Planning and delivery of intensity-modulated radiation therapy
Medical Physics, 2008
Intensity modulated radiation therapy ͑IMRT͒ is an advanced form of external beam radiation therapy. IMRT offers an additional dimension of freedom as compared with field shaping in threedimensional conformal radiation therapy because the radiation intensities within a radiation field can be varied according to the preferences of locations within a given beam direction from which the radiation is directed to the tumor. This added freedom allows the treatment planning system to better shape the radiation doses to conform to the target volume while sparing surrounding normal structures. The resulting dosimetric advantage has shown to translate into clinical advantages of improving local and regional tumor control. It also offers a valuable mechanism for dose escalation to tumors while simultaneously reducing radiation toxicities to the surrounding normal tissue and sensitive structures. In less than a decade, IMRT has become common practice in radiation oncology. Looking forward, the authors wonder if IMRT has matured to such a point that the room for further improvement has diminished and so it is pertinent to ask what the future will hold for IMRT. This article attempts to look from the perspective of the current state of the technology to predict the immediate trends and the future directions. This article will ͑1͒ review the clinical experience of IMRT; ͑2͒ review what we learned in IMRT planning; ͑3͒ review different treatment delivery techniques; and finally, ͑4͒ predict the areas of advancements in the years to come.
Intensity modulated radiotherapy (IMRT) the white, black and grey: a clinical perspective
Reports of Practical Oncology & Radiotherapy, 2009
The radiotherapy community has in the past few decades witnessed dramatic shift in the treatment modalities from conventional 2-D radiotherapy to the now widely practiced 3-DCRT, IMRT and evolving IGRT. IMRT has generated so much interest because of it s unique dosimetric modulation to concentrate doses to the targets of interests while also being able to relatively spare neighboring normal tissue. However IMRT is not the all in one solution for radiotherapeutic management of solid malignancies. The current enthusiasm in IMRT most be tempered with an understanding of the complexities of IMRT planning, treatment delivery, quality assurance, monitoring and clinical limitations. The widespread implementation of this technological innovat ion may have been a bit premature considering that clinical information regarding the same is still being generated. This article tries to give an overview of the potential advantages/disadvantages of IMRT in the clinical set up and the few controversies (Grey Zone) that are still being resolved. There is evidence to indicate that indiscriminately used IMRT may even harm the patient or have an inferior therapeutic index to 3DCRT. This and other pertinent issues will be covered by the authors in this short review of IMRT in clinical practice.
Intensity-modulated radiotherapy: current status and issues of interest
International Journal of Radiation Oncology*Biology*Physics, 2001
Scanned photon and electron beam IMRT Tomotherapy IMRT Conventional multileaf collimator IMRT Physical modulator (compensating filter) IMRT Robotic linear accelerator IMRT COMPUTER OPTIMIZATION Objective functions Computer optimization (search) process Leaf sequence generation DOSE DISTRIBUTION AND MONITOR UNIT CALCULATIONS FOR IMRT Calculation algorithm types Important issues for IMRT dose calculations Monitor unit calculations for IMRT Recommendations: IMRT dose calculations IMRT ACCEPTANCE TESTING, COMMISSIONING, AND QA Acceptance testing of the IMRT treatment planning system Verification of IMRT dose distributions IMRT treatment plan test cases QA checks of monitor unit calculations IMRT treatment verification Recommendations: Acceptance testing, commissioning, and QA of IMRT systems and treatment verification FACILITY PLANNING AND RADIATION SAFETY Workload estimates Dose rate and calibration changes Shielding design Patient whole-body dose Recommendations: Facility planning and radiation safety TARGET VOLUME AND DOSE SPECIFICATION AND REPORTING
Intensity-modulated radiation therapy (IMRT): the radiation oncologist's perspective
Medical dosimetry : official journal of the American Association of Medical Dosimetrists, 2002
Intensity-modulated radiation therapy (IMRT) is a new and evolving technological advance in high-precision radiation therapy. It is an extension of 3-dimensional conformal radiotherapy (3D-CRT) that allows the delivery of highly complex isodose profiles to the target while minimizing radiation exposure to surrounding normal tissues. Clinical data on IMRT are emerging and being collected, as more institutions are implementing or expanding the use of IMRT. However, the currently available IMRT and its applications are far from being well understood and established. In some circumstances, it remains impractical and too costly. This article discusses some practical issues from the radiation oncologist's perspective.
Intensity modulated radiation therapy: a clinical review
The British Journal of Radiology, 2000
Intensity modulated radiotherapy represents a signi®cant advance in conformal radiotherapy. In particular, it allows the delivery of dose distributions with concave isodose pro®les such that radiosensitive normal tissue close to, or even within a concavity of, a tumour may be spared from radiation injury. This article reviews the clinical application of this technique to date, and discusses the practical issues of treatment planning and delivery from the clinician's perspective.
A review of intensity-modulated radiation therapy
Current Oncology Reports, 2008
Intensity-modulated radiation therapy (IMRT) is a sophisticated form of three-dimensional treatment planning and delivery. In some situations, IMRT allows more conformal radiation therapy to complex targets within the lung. As problems related to organ motion are increasingly addressed, the use of IMRT in the treatment of lung cancer, particularly in non-small cell lung cancer and mesothelioma, continues to rise.
New developments in intensity modulated radiation therapy
Technology in cancer research & treatment, 2006
As intensity modulated radiation therapy (IMRT) becomes routine clinical practice, its advantages and limitations are better understood. With these new understandings, some new developments have emerged in an effort to alleviate the limitations of the current IMRT practice. This article describes a few of these efforts made at the University of Maryland, including: i) improving IMRT efficiency with direct aperture optimization; ii) broadening the scope of optimization to include the mode of delivery and beam angles; and iii) new planning methods for intensity modulated arc therapy (IMAT).
Medical Physics, 2003
Intensity-modulated radiation therapy ͑IMRT͒ represents one of the most significant technical advances in radiation therapy since the advent of the medical linear accelerator. It allows the clinical implementation of highly conformal nonconvex dose distributions. This complex but promising treatment modality is rapidly proliferating in both academic and community practice settings. However, these advances do not come without a risk. IMRT is not just an add-on to the current radiation therapy process; it represents a new paradigm that requires the knowledge of multimodality imaging, setup uncertainties and internal organ motion, tumor control probabilities, normal tissue complication probabilities, three-dimensional ͑3-D͒ dose calculation and optimization, and dynamic beam delivery of nonuniform beam intensities. Therefore, the purpose of this report is to guide and assist the clinical medical physicist in developing and implementing a viable and safe IMRT program. The scope of the IMRT program is quite broad, encompassing multileaf-collimatorbased IMRT delivery systems, goal-based inverse treatment planning, and clinical implementation of IMRT with patient-specific quality assurance. This report, while not prescribing specific procedures, provides the framework and guidance to allow clinical radiation oncology physicists to make judicious decisions in implementing a safe and efficient IMRT program in their clinics.