Magnetic resonance linear accelerator technology and adaptive radiation therapy: An overview for clinicians.

Radiation therapy (RT) continues to play an important role in the treatment of cancer. Adaptive RT (ART) is a novel method through which RT treatments are evolving. With the ART approach, computed tomography or magnetic resonance (MR) images are obtained as part of the treatment delivery process. This enables the adaptation of the irradiated volume to account for changes in organ and/or tumor position, movement, size, or shape that may occur over the course of treatment. The advantages and challenges of ART maybe somewhat abstract to oncologists and clinicians outside of the specialty of radiation oncology. ART is positioned to affect many different types of cancer. There is a wide spectrum of hypothesized benefits, from small toxicity improvements to meaningful gains in overall survival. The use and application of this novel technology should be understood by the oncologic community at large, such that it can be appropriately contextualized within the landscape of cancer therapies. Likewise, the need to test these advances is pressing. MR-guided ART (MRgART) is an emerging, extended modality of ART that expands upon and further advances the capabilities of ART. MRgART presents unique opportunities to iteratively improve adaptive image guidance. However, although the MRgART adaptive process advances ART to previously unattained levels, it can be more expensive, time-consuming, and complex. In this review, the authors present an overview for clinicians describing the process of ART and specifically MRgART.

The development of dose planning.

In the very earliest days, there was no computerized dose-planning system. However, it was not long that the first dose-planning system KULA was developed in the mid-1980s. It soon became apparent that while this was geometrically accurate, it was not as visually attractive as programs used by other technologies. It had been designed in the era prior to computerized imaging and had only limited capacity for dosimetry. It was followed by GammaPlan, which has evolved over the years into a sophisticated multiparameter system with very advanced graphic features.

Radiotherapy for soft tissue sarcoma: 50 years of change and improvement.

Radiotherapy for soft tissue sarcoma (STS) has advanced significantly over the past 50 years. This review focuses briefly on the period from 1964 to 1999 and more substantially on the changes of the past 15 years, such as IMRT and image-guided radiotherapy (IG-RT), especially when brought together (IG-IMRT) in the same planning and delivery process to treat localized STS. In particular, the introduction of IG-RT, target volume definitions for IG-RT, and review of recent clinical trials using IG-RT to treat localized STS in extremity will be reviewed. Finally, potential investigational agents combined with IG-RT to improve outcomes in patients with localized STS are discussed.

[Technical and methodical developments of radiation oncology from a physician's point of view]. / Die technischen und methodischen Entwicklungen der Radioonkologie aus ärztlicher Sicht.

Technical and methodical developments have changed radiation oncology substantially over the last 40 years. Modern imaging methods, e.g., computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), and ultrasound (US), have not only improved the detection of tumors but have also become tools for computed treatment planning. Megavoltage irradiation with accelerators using photons and electrons with large and small fields, intensity modulation (IMRT), image-guided radiotherapy (IGRT), stereotactic irradiation and radiosurgery, intraoperative radiotherapy (IORT), and modern remote controlled afterloading brachytherapy have made high precision radiotherapy increasingly possible. Hadron therapy has potential for further developments. Radiation oncology today is an interdisciplinary modality and increasingly considers interactions with new drugs and differentiated surgical methods. There is a strong need for comprehensive evaluation of the new methods and also for translational research in biology of tumors and normal tissue biology as well as in medical physics and techniques.

Image guidance in radiation oncology treatment planning: the role of imaging technologies on the planning process.

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.

A (short) history of image-guided radiotherapy.

Progress in radiotherapy is guided by the need to realize improved dose distributions, i.e. the ability to reduce the treatment volume toward the target volume and still ensuring coverage of that target volume in all dimensions. Poor ability to control the tumour's location limits the accuracy with which radiation can be delivered to tumour-bearing tissue. Image-guided radiation therapy (IGRT) aims at in-room imaging guiding the radiation delivery based on instant knowledge of the target location and changes in tumour volume during treatment. Advancements are usually not to be attributed to a single event, but rather a combination of many small improvements that together enable a superior result. Image-guidance is an important link in the treatment chain and as such a major factor in this synergetic process. A historic review shows that many of the so-called new developments are not so new at all, but did not make it into mainstream radiotherapy practice at that time. Recent developments in improved IT infrastructures, novel irradiation techniques, and better knowledge of functional and morphologic information may have created the need and optimal environment to revive the interest in IGRT.

[The first Hungarian radiotherapy department was founded at Uzsoki Street Hospital 75 years ago]. / 75 éves az önálló sugárterápia az Uzsoki utcai Kórházban.

The first Hungarian radiotherapy department treating cancer patients by using 226Ra brachytherapy was founded in the Uzsoki Hospital 75 years ago. This institution represented the European level of the 1930s. The authors are presenting a brief summary of the main activities and the technical development of the Municipal Oncoradiological Centre as well as scientific investigations at the beginning of the 21st century.

History of tomotherapy.

Tomotherapy is the delivery of intensity modulated radiation therapy using rotational delivery of a fan beam in the manner of a CT scanner. In helical tomotherapy the couch and gantry are in continuous motion akin to a helical CT scanner. Helical tomotherapy is inherently capable of acquiring CT images of the patient in treatment position and using this information for image guidance. This review documents technological advancements of the field concentrating on the conceptual beginnings through to its first clinical implementation. The history of helical tomotherapy is also a story of technology migration from academic research to a university-industrial partnership, and finally to commercialization and widespread clinical use.

Modern radiation treatment planning and delivery--from Röntgen to real time.

The field of radiation oncology has advanced exponentially since the discovery of X-rays just over 100 years ago. With the advent of three-dimensional treatment planning, the therapeutic index was increased by dose escalation and more accurate shielding of normal tissues. Now, even greater advances are under way with IMRT, image-guided radiation therapy, delineation and control of organ motion, and real-time imaging. Similarly, the use of particle therapies such as protons has the potential to effect even more accurate dose distributions. Clinical studies investigating these modalities will likely further increase the efficacy of radiation in years to come.

The dosimetry system DS86 and the neutron discrepancy in Hiroshima--historical review, present status, and future options.

The historical development of the dosimetry systems for Hiroshima and Nagasaki is outlined from the time immediately after the A-bomb explosions to the publication of the dosimetry system DS86 in 1987, and the present status of the so-called Hiroshima neutron discrepancy is summarized. Several long-lived radionuclides are discussed with regard to their production by neutrons from the A-bomb explosions. With the exception of 63Ni, these radionuclides have not, up to now, been measured in samples from Hiroshima and Nagasaki. Two of them, 63Ni in copper samples and 39Ar in granite samples, were predominantly produced by fast neutrons. 63Ni can be determined by accelerator mass spectrometry with a gas-filled analyzing magnet. It should be measurable, in the near future, in copper samples up to 1500 m from the hypocenter in Hiroshima. 39Ar can be measured in terms of low-level beta-counting. This should be feasible up to a distance of about 1000 m from the hypocenter. Three radionuclides, 10Be, 14C, and 59Ni, were produced predominantly by thermal neutrons with smaller fractions due to the epithermal and fast neutrons, which contribute increasingly more at larger distances from the hypocenter. State-of-the-art accelerator mass spectrometry is likely to permit the determination of 10Be close to the hypocenter and of 14C up to a distance of about 1000 m. 59Ni should be detectable up to a distance of about 1000 m in terms of accelerator mass spectrometry with a gas-filled magnet. The measurements of 10Be, 14C, 39Ar, 59Ni -- and potentially of 131Xe -- can be performed in the same granitic sample that was already analyzed for 36Cl, 41Ca, 6Co, 152Eu, and 154Eu. This will provide extensive information on the neutron spectrum at the specified location, and similarly complete analyses can conceivably be performed on granite samples at other locations.

The development of conformal radiation therapy.

The development and clinical use of conformal radiation therapy, and the application of modern computer-controlled radiation therapy treatment techniques to the delivery of conformal therapy, has been a major research area in the field of radiation oncology in recent years. The introduction of three-dimensional (3-D) patient imaging, 3-D treatment planning systems, computer-controlled treatment machines equipped with multileaf collimators, and the continuing increase in computer power and software sophistication has finally allowed the clinical implementation of the kinds of conformal treatment planning and delivery that were envisioned decades ago. The use of 3-D treatment planning in conjunction with conformal treatments and the analysis of clinical normal tissue complications has also begun to give the field the clinical complication (and eventually tumor control) probability data which can be used to truly optimize radiation treatments. At this centennial anniversary of the discovery of the x ray, it is appropriate to look back at the contributions which have led to the current developments in conformal therapy. Few if any of the "new developments" associated with modern computer-controlled conformal therapy (CCRT) are actually new. However, modern technology has finally progressed to the point that we can integrate all of the features that are necessary to really make the concepts work in the clinic. This paper traces some of the developments which have led to the current interest and progress in CCRT treatments. A brief summary of the current status of conformal therapy and the work still to be done is also included.

The application of automatic computing machines to radiation treatment planning. 1954.

A new method of determining the dose distribution required in treatment planning has been developed by using punched cards, and sorting and tabulating machines instead of isodose charts. The percentage depth doses produced by an X-ray field are first recorded on several sets of punched cards. The number of sets required for one field depends upon the distances used from the cross point of the multifield axes to the point of entry. Each set consists of 36 cards, with each card recording the percentage depth doses of 15 points in one radial line, taking the cross points of central axes of the fields as the origin. In all cases the points are taken at the distances 0, 1, 2, 3, 4, 5, 6, 8, 10, 12, 14, 16, 18, 20, 24 cm from the origin and along radial lines 10 deg. apart. A special polar co-ordinate dose distribution sheet has been designed, and the contour of the patient's body and the position of the fields designated for treatment are drawn on this sheet. Instead of putting the isodose charts at the proper positions of the fields, the sets of punched cards for the fields to be applied are automatically arranged in the right order. Instead of the time-consuming process of reading off the percentage depth doses from the overlapping isodose charts and adding them up for selected points, the cards are fed into the automatic tabulating machine, which makes the summation of data for all the points mentioned above and tabulates the results. The whole operation is done in 10 to 15 minutes. The tabulated results are then plotted on the special dose distribution sheet. A generalised mathematical treatment of the dose at any point in the irradiated region is discussed, and an equation of "point-tumour dose ratio" is derived. Further application of this equation is made to special cases for treatment using equal maximum doses, equal tumour doses and rotation therapy. The geometrical principles involved are also indicated.

Three-dimensional treatment planning and conformal radiation dose delivery.

Three-dimensional treatment planning and conformal dose delivery have the potential to increase the effectiveness of radiation treatments. For the first time, it is possible to ensure that the intended target is being treated with the full, desired dose. By restricting the high dose region to conform more closely to the shape of the target, normal tissues receive a smaller percentage of the dose, allowing doses to be escalated to the target. New equipment, including multileaf collimators and computer-controlled treatment machines, along with faster and more sophisticated planning systems, are making 3-D planning and treatment delivery increasingly practical. The final impact of these new techniques on the ultimate outcome of a course of radiation will be ascertained through continuing clinical experience and through ongoing clinical trials.