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The authors discuss software interface concerns in radiation oncology from a human factors perspective. An example of a series of disastrous consequences resulting from a poorly developed and tested interface design of a computer controlled treatment machine is described. Treatment planning computers are discussed in terms of their increasing requirement to provide complex data to the user resulting in the possibility of confusing the output or overloading the user. Finally, the priority given to software-based human interfaces in other industries is compared to that found in radiation oncology equipment manufacturers. The authors argue that radiation oncology equipment manufacturers lag behind other industries in terms of their emphasis on the human interface. >

A series of human factors evaluations were undertaken to better understand the contributing factors to human error in the teletherapy environment. Teletherapy is a multidisciplinary methodology for treating cancerous tissue through selective exposure to an external beam of ionizing radiation. A team of human factors specialists, assisted by a panel of radiation oncologists, medical physicists, and radiation therapists, conducted site visits to radiation oncology departments at community hospitals, university centers, and free-standing clinics. A function and task analysis was performed initially to guide subsequent evaluations in the areas of workplace environment, system-user interfaces, procedures, training, and organizational practices. To further acquire an in-depth and up-to-date understanding of the practice of teletherapy in support of these evaluations, a systematic literature review was conducted. Factors that have a potential impact on the accuracy of treatment delivery were of primary concern. The present volume is the literature review. The volume starts with an overview of the multiphased nature of teletherapy, and then examines the requirement for precision, the increasing role of quality assurance, current conceptualizations of human error, and the role of system factors such as the workplace environment, user-system interfaces, procedures, training, and organizational practices.

As a treatment methodology, teletherapy selectively destroys cancerous and other tissue by exposure to an external beam of ionizing radiation. Sources of radiation are either a radioactive isotope, typically Cobalt-60 (Co-60), or a linear accelerator. Records maintained by the NRC have identified instances of teletherapy misadministration where the delivered radiation dose has differed from the radiation prescription (e.g., instances where fractions were delivered to the wrong patient, to the wrong body part, or were too great or too little with respect to the defined treatment volume). Both human error and machine malfunction have led to misadministrations. Effective and safe treatment requires a concern for precision and consistency of human-human and human-machine interactions throughout the course of therapy. The present study is the first part of a series of human factors evaluations for identifying the root causes that lead to human error in the teletherapy environment. The human factors evaluations included: (1) a function and task analysis of teletherapy activities, (2) an evaluation of the human-system interfaces, (3) an evaluation of procedures used by teletherapy staff, (4) an evaluation of the training and qualifications of treatment staff (excluding the oncologists), (5) an evaluation of organizational practices and policies, and (6) anmore » identification of problems and alternative approaches for NRC and industry attention. The present report addresses the function and task analysis of teletherapy activities and provides the foundation for the conduct of the subsequent evaluations. The report includes sections on background, methodology, a description of the function and task analysis, and use of the task analysis findings for the subsequent tasks. The function and task analysis data base also is included.« less

A series of human factors evaluations was undertaken to better understand the contributing factors to human error in the teletherapy environment. Teletherapy is a multi-disciplinary methodology for treating cancerous tissue through selective exposure to an external beam of ionizing radiation. The principal sources of radiation are a radioactive isotope, typically cobalt60 (Co-60), or a linear accelerator device capable of producing very high energy x-ray and electron beams. A team of human factors specialists, assisted by a panel of radiation oncologists, medical physicists, and radiation technologists, conducted site visits to radiation oncology departments at community hospitals, university centers, and free-standing clinics. A function and task analysis was initially performed to guide subsequent evaluations in the areas of user-system interfaces, procedures, training and qualifications, and organizational policies and practices. The final phase of the project focused on identification of the most significant human factors problems with respect to safe and effective operation of the teletherapy system and an identification and assessment of alternative approaches for resolving the problems. This report presents the findings of this final phase.

A series of human factors evaluations were undertaken to better understand the contributing factors to human error in the teletherapy environment. Teletherapy is a multidisciplinary methodology for treating cancerous tissue through selective exposure to an external beam of ionizing radiation. A team of human factors specialists, assisted by a panel of radiation oncologists, medical physicists, and radiation therapists, conducted site visits to radiation oncology departments at community hospitals, university centers, and free-standing clinics. A function and task analysis was initially performed to guide subsequent evaluations in the areas of system-user interfaces, procedures, training and qualifications, and organizational policies and practices. The present work focuses solely on training and qualifications of personnel (e.g., training received before and during employment), and the potential impact of organizational factors on the performance of teletherapy. Organizational factors include such topics as adequacy of staffing, performance evaluations, commonly occurring errors, implementation of quality assurance programs, and organizational climate.

A series of human factors evaluations was undertaken to better understand the contributing factors to human error in the teletherapy environment. Teletherapy is a multidisciplinary methodology for treating cancerous tissue through selective exposure to an external beam of ionizing radiation. The principal sources of radiation are a radioactive isotope, typically cobalt60 (Co-60), or a linear accelerator device capable of producing very high energy x-ray and electron beams. A team of human factors specialists conducted site visits to radiation oncology departments at community hospitals, university centers, and free-standing clinics. In addition, a panel of radiation oncologists, medical physicists, and radiation technologists served as subject matter experts. A function and task analysis was initially performed to guide subsequent evaluations in the areas of user-system interfaces, procedures, training and qualifications, and organizational policies and practices. The present report focuses on an evaluation of the human-system interfaces in relation to the treatment machines and supporting equipment (e.g., simulators, treatment planning computers, control consoles, patient charts) found in the teletherapy environment. The report also evaluates operating, maintenance and emergency procedures and practices involved in teletherapy. The evaluations are based on the function and task analysis and established human engineering guidelines, where applicable.

Square lattice models for the general dimer and trimer problems are considered. A secondary lattice for the dimer problem is constructed, and a double square Kikuchi calculation produces an athermal molecular freedom within 2% of the known exact result. With interactions, departures from ideality of mixing entropy and vapour pressure are calculated at different temperatures, and an asymmetrical phase separation occurs at a reduced temperature 0.08. The general trimer problem is considered in a single square Kikuchi calculation. A single interaction is included. The molecular freedom and thermodynamic non-ideality of rigid linear, rigid angled and flexible trimers are compared. In the rigid linear case a phase separation occurs at reduced temperature 0.04. The molecular freedom of rigid linear trimers is calculated using higher Kikuchi approximations, and the result agrees well with previous estimates.

A lattice fluid in which molecules can have orientation-dependent interactions is considered. It is found that a high density transition to an orientationally ordered state can be produced if a particular interaction between molecules in a specific relative orientation is dominant. The transition is second order and can be related to transitions found experimentally in lipid monolayers. If all interactions are attractive a separate low density condensation can coexist with the orientational transition.

Oven temperatures traditionally have been used to determine cooking time. Other factors, such as fat content of meat, also affect cooking rates, as this study shows.