Considerations of Cost-Effectiveness for New Radiation Oncology Technologies

PURPOSE

The additional equipment and personnel costs of supplying image-guided radiation therapy (IGRT) technology have caused many to question if the marginal gains in patients' health-related quality of life are worth the additional cost. Novel IGRT technologies, including cone-beam computed tomography and helical tomotherapy, provide the opportunity to study cost and effectiveness for patients.

MATERIALS AND METHODS

This methodologic study proposes to evaluate the cost and effectiveness of treating conventional radiotherapy versus IGRT patients prospectively among several institutions. The cost of treating patients varies among institutions depending on personnel, equipment, and overhead costs, but the nature and quality of services provided are expected to be consistent.

RESULTS

The study will track cost information at a single institution and simultaneously as the median from multiple institutions. Effectiveness measures will include both standard quality-adjusted life-year instruments completed by patients and performance status measures completed by institutional personnel. In addition, disease-specific effectiveness measures will be accommodated in the study. Each participating institution will use the same effectiveness measures to track patients with similar diseases.

CONCLUSION

The resulting cost and effectiveness data will be available to investigators at any point during the study, immediately on the completion of a trial, or when statistical acceptability is achieved. These considerations are being incorporated into a high-level information model under development.

Ultra-high resolution flat-panel volume CT: fundamental principles, design architecture, and system characterization

Digital flat-panel-based volume CT (VCT) represents a unique design capable of ultra-high spatial resolution, direct volumetric imaging, and dynamic CT scanning. This innovation, when fully developed, has the promise of opening a unique window on human anatomy and physiology. For example, the volumetric coverage offered by this technology enables us to observe the perfusion of an entire organ, such as the brain, liver, or kidney, tomographically (e.g., after a transplant or ischemic event). By virtue of its higher resolution, one can directly visualize the trabecular structure of bone. This paper describes the basic design architecture of VCT. Three key technical challenges, viz., scatter correction, dynamic range extension, and temporal resolution improvement, must be addressed for successful implementation of a VCT scanner. How these issues are solved in a VCT prototype and the modifications necessary to enable ultra-high resolution volumetric scanning are described. The fundamental principles of scatter correction and dose reduction are illustrated with the help of an actual prototype. The image quality metrics of this prototype are characterized and compared with a multi-detector CT (MDCT).

Advances in ultrasound move modality into new fields

For decades, ultrasound has served as an easy-to-use, noninvasive imaging specialty that yielded results both immediately and cost effectively. In the past, medical imaging technology developers focused solely on building ultrasound systems that delivered excellent images. However, over the last decade, as patient and clinical needs evolved, medical imaging manufacturers found themselves adjusting quickly to build systems to meet new market demands. This shift has spurred tremendous technological advancements and enhanced ultrasound's role in the clinical management of a wide range of disease states, including obesity, diabetes, and breast cancer. Ultrasound has become a leader in delivering ergonomically technologies that take into account the needs of clinicians, making this modality one of the most accommodating when it comes to ensuring the long-term safety of today's sonographer.

Therapeutic Radiation Physics Primer

Therapeutic radiological physics is the branch of physics as applied to radiation therapy. Therapeutic radiological physics involves the understanding of the radiation sources, types, and characteristics of radiation, interaction of radiation with matter, and thereafter the deposition of energy in matter. In clinical practice, therapeutic radiological physics deals with the technical tasks of preparing a patient to undergo radiation therapy. These tasks include simulation, patient data acquisition, individualized planning, verification, and dose delivery. The role of a therapeutic radiological physicist is to manage the technical aspects of patient care: providing technical expertise to the development of the institution, recommending and introducing new treatment techniques, and ensuring that all patients undergoing radiation therapy receive the best standard of care.

Accuracy and consistency of radiographic interpretation among clinical instructors using two viewing systems

Accurate and consistent radiographic interpretation among clinical instructors is needed for assessment of teaching, student performance, and patient care. The purpose of this investigation was to determine if the method of radiographic viewing affects accuracy and consistency of instructors' determinations of bone loss. Forty-one clinicians who provide instruction in a dental school clinical teaching program (including periodontists, general dentists, periodontal graduate students, and dental hygienists) quantified bone loss for up to twenty-five teeth into four descriptive categories using a view box for plain film viewing or a projection system for digitized image viewing. Ratings were compared to the correct category as determined by direct measurement using the Schei ruler. Agreement with the correct choice for the view box and projection system was 70.2 percent and 64.5 percent, respectively. The mean difference was better for a projection system due to small rater error by graduate students. Projection system ratings were slightly less consistent than view box ratings. Dental hygiene faculty ratings were the most consistent but least accurate. Although the projection system resulted in slightly reduced accuracy and consistency among instructors, training sessions utilizing a single method for projecting digitized radiographic images have their advantages and may positively influence dental education and patient care by enhancing accuracy and consistency of radiographic interpretation among instructors.

Exposure of Brain to High-Dose, Focused Gamma Rays Irradiation Produces Increase in Leukocytes-Adhesion and Pavementing in Small Intracerebral Blood Vessels

OBJECTIVE

Radiosurgery is used to destroy a predetermined target within the brain, with minimal radiation injury to the surrounding tissue. We hereby present our in vivo model to study the effects of single-session, high-dose radiation on the cerebral vessels that are targeted with radiosurgery using the Leksell Gamma Knife.

METHODS

The study was conducted in 29 adult male WT C57BL/6J mice weighing 21 to 28 g (6-8 wk old). The animals were exposed to 100 Gy single-session focused gamma ray irradiation using the Leksell Gamma Knife, and subsequently underwent intravital microscopy at different time intervals to study leukocytes and platelets adhesion patterns to the endothelium of the irradiated cerebral micro-vessels.

RESULTS

The leukocyte adhesion response showed a bell-shaped curve upon quantitative analysis with a steady increase in the number of adherent cells during the first four hours and a subsequent plateau response that was maintained during the next 24 hours. The platelet adhesion response did not demonstrate any particular pattern similar to the leukocyte response.

CONCLUSION

The experiment was able to establish in vivo increased leukocyte adhesion to the cerebral vascular endothelial cells in response to radiation injury and elaborate the time frame within which the leukocyte adhesion response increases, reaches a peak and then starts decreasing.

Physical properties and ease of operation of a wireless intraoral x-ray sensor

OBJECTIVE

A wireless CMOS (CDR Wireless) system was evaluated based on its physical properties and ease of operation.

STUDY DESIGN

The physical properties were assessed by dose-response curve, modulation transfer function, and detective quantum efficiency tests. The range of signal receptivity between the sensor and the antenna was also determined. The time required to make a radiograph was measured. Using a visual analog scale (VAS), 10 test patients were asked to evaluate the discomfort caused by having the sensor inserted and placed in the mouth. An intraoral x-ray film packet and a wired CDR sensor were also evaluated for comparison with the wireless system.

RESULTS

The physical properties of the wireless system and the wired CDR sensor were essentially equal. The antenna could receive the signal up to 3.5 m from the sensor. The wireless CMOS system required less time to perform the radiographic task than the other methods studied. The VAS scores for the wireless and wired CDR sensors were comparable.

CONCLUSIONS

The CDR Wireless sensor has equivalent physical properties to its wired counterpart and may be more convenient to use.

Microcontrolled pyro-electric instrument for measuring X-ray intensity in mammography

A novel instrument for measurement of X-ray intensity from mammography consists of a sensitive pyro-electric detector, a high-sensitivity, low-noise current-to-voltage converter, a microcontroller and a digital display. The heart of this device, and what makes it unique is the pyro-electric detector, which measures radiation by converting heat from absorbed incident X-rays into an electric current. This current is then converted to a voltage and digitised. The detector consists of a ferro-electric crystal; two types were tested: lithium tantalate and lithium niobate. X-ray measurement in mammography is challenging because of its relatively low photon energy range, from 11 keV to 15 keV equivalent mean energy, corresponding to a peak tube potential from 22 to 36 kV. Consequently, energy fluence rate or intensity is low compared with that of common diagnostic X-ray. The instrument is capable of measuring intensities as low as 0.25 mW m(-2) with precision greater than 99%. Not only was the instrument capable of performing in the clinical environment, with high background electromagnetic interference and vibration, but its performance was not degraded after being subjected to 140 roentgen (3.6 x 10(-2) C kg(-2) air) as measured by piezo-electric (d33) or pyro-electric coefficients.

[Comments on the standards for acceptance and consistency testing of systems for digital radiography]

Due to German regulations, acceptance and consistency tests have to be obtained by 12.31.2005 for all equipment used for computed radiography according to special standards published in DIN 6868. This article familiarizes all users with the most important aspects of these standards. In addition, explanatory and background information for establishing these regulations are provided.

Medical Devices and the US Food and Drug Administration: Regulating the Tools of Radiology

The radiology community has an ever-expanding array of technologies to use in the care of patients. Regulated by the US Food and Drug Administration, these technologies often raise complex regulatory and legal questions in everyday practice that can be daunting for practicing radiologists. This article reviews the federal medical device regulatory framework pertinent to the practice of radiology, with the aims of highlighting the potential impact of federal regulation on everyday practice and minimizing misunderstandings about enforcement exposure.

Flat detectors and their clinical applications

Diagnostic and interventional flat detector X-ray systems are penetrating the market in all application segments. First introduced in radiography and mammography, they have conquered cardiac and general angiography and are getting increasing attention in fluoroscopy. Two flat detector technologies prevail. The dominating method is based on an indirect X-ray conversion process, using cesium iodide scintillators. It offers considerable advantages in radiography, angiography and fluoroscopy. The other method employs a direct converter such as selenium which is particularly suitable for mammography. Both flat detector technologies are based on amorphous silicon active pixel matrices. Flat detectors facilitate the clinical workflow in radiographic rooms, foster improved image quality and provide the potential to reduce dose. This added value is based on their large dynamic range, their high sensitivity to X-rays and the instant availability of the image. Advanced image processing is instrumental in these improvements and expand the range of conventional diagnostic methods. In angiography and fluoroscopy the transition from image intensifiers to flat detectors is facilitated by ample advantages they offer, such as distortion-free images, excellent coarse contrast, large dynamic range and high X-ray sensitivity. These characteristics and their compatibility with strong magnetic fields are the basis for improved diagnostic methods and innovative interventional applications.

Infrastructure of radiation oncology in France: a large survey of evolution of external beam radiotherapy practice

PURPOSE

To study the structural characteristics of radiation oncology facilities for France and to examine how technological evolutions had to be taken into account in terms of accessibility and costs. This study was initiated by the three health care financing administrations that cover health care costs for the French population. The needs of the population in terms of the geographic distribution of the facilities were also investigated. The endpoint was to make proposals to enable an evolution of the practice of radiotherapy (RT) in France.

METHODS AND MATERIALS

A survey designed by a multidisciplinary committee was distributed in all RT facilities to collect data on treatment machines, other equipment, personnel, new patients, and new treatments. Medical advisors ensured site visits in each facility. The data were validated at the regional level and aggregated at the national level for analysis.

RESULTS

A total of 357 machines had been installed in 179 facilities: 270 linear accelerators and 87 cobalt units. The distribution of facilities and megavoltage units per million inhabitants over the country was good, although some disparities existed between areas. It appeared that most megavoltage units had not benefited from technological innovation, because 25% of the cobalt units and 57% of the linear accelerators were between 6 and 15 years old. Computed tomography access for treatment preparation was not sufficient, and complete data management systems were scarce (15% of facilities). Seven centers had no treatment planning system. Electronic portal imaging devices were available in 44.7% of RT centers and in vivo dosimetry in 35%. A lack of physicians and medical physicists was observed; consequently, the workload exceeded the normal standard recommended by the French White Book. Discrepancies were found between the number of patients treated per machine per year in each area (range, 244.5-604). Most treatments were delivered in smaller facilities (61.6%).

CONCLUSION

On the basis of the findings of this study, measures were taken to update the infrastructure of RT in France. A first evaluation showed an improvement of care supply in RT in the country.

New x-ray tube performance in computed tomography by introducing the rotating envelope tube technology

The future demands of computed tomography imaging regarding the x-ray source can be summarized with higher scan power, shorter rotation times, shorter cool down times and smaller focal spots. We report on a new tube technology satisfying all these demands by making use of a novel cooling principle on one hand and of a novel beam control system on the other hand. Nowadays tubes use a rotating anode disk mainly cooled via radiation. The Straton x-ray tube is the first tube available for clinical routine utilizing convective cooling exclusively. It is demonstrated that this cooling principle makes large heat storage capacities of the anode disk obsolete. The unprecedented cooling rate of 4.8 MHU/min eliminates the need for waiting times due to anode cooling in clinical workflow. Moreover, an electronic beam deflection system for focal spot position and size control opens the door to advanced applications. The physical backgrounds are discussed and the technical realization is presented. From this discussion the superior suitability of this tube to withstand g-forces well above 20 g created by fast rotating gantries will become evident. Experience from a large clinical trial is reported and possible ways for future developments are discussed.

Relevant training issues for introduction of digital radiology: results of a survey

Council Directive 97/43/Euratom establishes the need for adequate training of radiology staff. The transition to digital radiology implies changes in various imaging aspects, which are not sufficiently covered by current institutional training programmes. This work aimed to assess how professionals, experienced in digital imaging, acquired their expertise and hence, what form institutional training should take. Within DIMOND III, a survey on training and resources was performed among radiology professionals. A lack of institutional education for digital radiology was found. In the transition to digital radiology, 30-35% train on the job and another 23-28% receive training from digital equipment vendors. A general agreement exists on the need for new quality criteria and strategies for dose management. Issues relevant for conventional/digital transition are only sparsely covered in EC training programmes. Based on these results, a set of training issues was produced, to be included in future European guidelines.

Isocenter characteristics of an external ring proton gantry

PURPOSE

Determine the shape, size, geometric center, and virtual center of the isocenter for a proton gantry and compare to electron/X-ray accelerator gantries.

METHODS AND MATERIALS

The majority of commercial electron/X-ray accelerator gantries consist of a rotating treatment head mounted to a stationary stand through a slewing ring bearing. The world's first proton gantry uses two rotating external rings, to which is mounted a fixed treatment nozzle with a movable snout that extends close to the center of rotation. The radial aspect of the isocenter for two similar proton gantries and two different electron/X-ray gantries were measured in the gantry frame of reference with a front pointer and a theodolite. These results were then transformed into room coordinates. The axial aspect of the isocenter was measured with a dial indicator.

RESULTS

The radial aspect of the isocenter for slewing ring gantries has the shape of two concentric circles. The radial aspect of the isocenter for external ring gantries is shaped like a butterfly. The size of the mechanical isocenter is independent of the gantry style.

CONCLUSIONS

The locations of the geometric and virtual centers can be determined to within 0.2 mm. Multiple gantry angle treatments can be delivered with a single setup allowing 2 mm for gantry and nozzle deflections. Precision treatments can be delivered allowing only 0.5 mm if the measured isocenter path is applied.