A computerized record and verify system for radiation treatments

An Investigation of Radiation Treatment Learning Opportunities in Relation to the Radiation Oncology Electronic Medical Record: A Single Institution Experience

Purpose

A modern radiation oncology electronic medical record (RO-EMR) system represents a sophisticated human-computer interface with the potential to reduce human driven errors and improve patient safety. As the RO-EMR becomes an integral part of clinical processes, it may be advantageous to analyze learning opportunities (LO) based on their relationship with the RO-EMR. This work reviews one institution's documented LO to: (1) study their relationship with the RO-EMR workflow, (2) identify best opportunities to improve RO-EMR workflow design, and (3) identify current RO-EMR workflow challenges.

Methods and Materials

Internal LO reports for an 11-year contiguous period were categorized by their relationship to the RO-EMR. We also identify the specific components of the RO-EMR used or involved in each LO. Additionally, contributing factor categories from the ASTRO/AAPM sponsored Radiation Oncology Incident Learning System's (RO-ILS) nomenclature was used to characterize LO directly linked to the RO-EMR.

Results

A total of 163 LO from the 11-year period were reviewed and analyzed. Most (77.2%) LO involved the RO-EMR in some way. The majority of the LO were the results of human/manual operations. The most common RO-EMR components involved in the studied LO were documentation related to patient setup, treatment session schedule functionality, RO-EMR used as a communication/note-delivery tool, and issues with treatment accessories. Most of the LO had staff lack of attention and policy not followed as 2 of the highest occurring contributing factors.

Conclusions

We found that the majority of LO were related to RO-EMR workflow processes. The high-risk areas were related to manual data entry or manual treatment execution. An evaluation of LO as a function of their relationship with the RO-EMR allowed for opportunities for improvement. In addition to regular radiation oncology quality improvement review and policy update, automated functions in RO-EMR remain highly desirable.

Gamma Knife radiosurgery: Scenarios and support for re-irradiation

Stereotactic radiosurgery (SRS) involves the focal delivery of large, cytotoxic doses of radiation to small targets within the brain, often located in close proximity to radiosensitive normal tissue structures and requiring very low procedural uncertainties to perform safely. Historically, neurosurgeons considered SRS as a one-time, single session procedure. However therapeutic advances and a better understanding of the clinical response to SRS have caused a renewal of interest in a variety of re-irradiation scenarios; including re-irradiation of the same target after prior SRS, SRS treatments after prior broad-field radiation, hypofractionated treatments, and volume-staged treatments. Re-irradiation may in some cases require even greater effort towards minimizing treatment uncertainties as compared to one-time-only treatments. Gamma Knife radiosurgery (GKRS) has evolved over time in ways that directly supports many re-irradiation scenarios while helping to minimize overall procedural uncertainty.

A Robust and Affordable Table Indexing Approach for Multi-isocenter Dosimetrically Matched Fields

Purpose  Radiotherapy treatment planning of extended volume typically necessitates the utilization of multiple field isocenters and abutting dosimetrically matched fields in order to enable coverage beyond the field size limits. A common example includes total lymphoid irradiation (TLI) treatments, which are conventionally planned using dosimetric matching of the mantle, para-aortic/spleen, and pelvic fields. Due to the large irradiated volume and system limitations, such as field size and couch extension, a combination of couch shifts and sliding of patients are necessary to be correctly executed for accurate delivery of the plan. However, shifting of patients presents a substantial safety issue and has been shown to be prone to errors ranging from minor deviations to geometrical misses warranting a medical event. To address this complex setup and mitigate the safety issues relating to delivery, a practical technique for couch indexing of TLI treatments has been developed and evaluated through a retrospective analysis of couch position. Methods The indexing technique is based on the modification of the commonly available slide board to enable indexing of the patient position. Modifications include notching to enable coupling with indexing bars, and the addition of a headrest used to fixate the head of the patient relative to the slide board. For the clinical setup, a Varian Exact Couch^TM (Varian Medical Systems, Inc, Palo Alto, CA) was utilized. Two groups of patients were treated: 20 patients with table indexing and 10 patients without. The standard deviations (SDs) of the couch positions in longitudinal, lateral, and vertical directions through the entire treatment cycle for each patient were calculated and differences in both groups were analyzed with Student's t-test. Results The longitudinal direction showed the largest improvement. In the non-indexed group, the positioning SD ranged from 2.0 to 7.9 cm. With the indexing device, the positioning SD was reduced to a range of 0.4 to 1.3 cm (p < 0.05 with 95% confidence level). The lateral positioning was slightly improved (p < 0.05 with 95% confidence level), while no improvement was observed in the vertical direction. Conclusions The conventional matched field TLI treatment is error-prone to geometrical setup error. The feasibility of full indexing TLI treatments was validated and shown to result in a significant reduction of positioning and shifting errors.

Site-specific tolerance tables and indexing device to improve patient setup reproducibility

While the implementation of tools such as image-guidance and immobilization devices have helped to prevent geometric misses in radiation therapy, many treatments remain prone to error if these items are not available, not utilized for every fraction, or are misused. The purpose of this project is to design a set of site-specific treatment tolerance tables to be applied to the treatment couch for use in a record and verify (R&amp;V) system that will insure accurate patient setup with minimal workflow interruption. This project also called for the construction of a simple indexing device to help insure reproducible patient setup for patients that could not be indexed with existing equipment. The tolerance tables were created by retrospective analysis on a total of 66 patients and 1,308 treatments, separating them into five categories based on disease site: lung, head and neck (H&amp;N), breast, pelvis, and abdomen. Couch parameter tolerance tables were designed to encompass 95% of treatments, and were generated by calculating the standard deviation of couch vertical, longitudinal, and lateral values using the first day of treatment as a baseline. We also investigated an alternative method for generating the couch tolerances by updating the baseline values when patient position was verified with image guidance. This was done in order to adapt the tolerances to any gradual changes in patient setup that would not correspond with a mistreatment. The tolerance tables and customizable indexing device were then implemented for a trial period in order to determine the feasibility of the system. During this trial period we collected data from 1,054 fractions from 65 patients. We then analyzed the number of treatments that would have been out of tolerance, as well as whether or not the tolerances or setup techniques should be adjusted. When the couch baseline values were updated with every imaging fraction, the average rate of tolerance violations was 10% for the lung, H&amp;N, abdomen, and pelvis treatments. Using the indexing device, tolerances for patients with pelvic disease decreased (e.g., from 5.3 cm to 4.3 cm longitudinally). Unfortunately, the results from breast patients were highly variable due to the complexity of the setup technique, making the couch an inadequate surrogate for measuring setup accuracy. In summary, we have developed a method to turn the treatment couch parameters within the R&amp;V system into a useful alert tool, which can be implemented at other institutions, in order to identify potential errors in patient setup.

Technical note: electronic chart checks in a paperless radiation therapy clinic

PURPOSE

EcCk, which stands for Electronic Chart ChecK, is a computer software and database system. It was developed to improve quality and efficiency of patient chart checking in radiation oncology departments. The core concept is to automatically collect and analyze patient treatment data, and to report discrepancies and potential concerns.

METHODS

EcCk consists of several different computer technologies, including relational database, DICOM, dynamic HTML, and image processing. Implemented in MATLAB and C#, EcCk processes patient data in DICOM, PDF, Microsoft Word, database, and Pinnacle native formats. Generated reports are stored on the storage server and indexed in the database. A standalone report-browser program is implemented to allow users to view reports on any computer in the department. Checks are performed according to predefined logical rules, and results are presented through color-coded reports in which discrepancies are summarized and highlighted. Users examine the reports and take appropriate actions. The core design is intended to automate human task and to improve the reliability of the performed tasks. The software is not intended to replace human audits but rather to aid as a decision support tool.

RESULTS

The software was successfully implemented in the clinical environment and has demonstrated the feasibility of automation of this common task with modern clinical tools. The software integrates multiple disconnected systems and successfully supports analysis of data in diverse formats.

CONCLUSIONS

While the human is the ultimate expert, EcCk has a significant potential to improve quality and efficiency of patient treatment record audits, and to allow verification of tasks that are not easily performed by humans. EcCk can potentially relieve human experts from simple and repetitive tasks, and allow them to work on other important tasks, and in the end to improve the quality and safety of radiation therapy treatments.

Analysis of couch position tolerance limits to detect mistakes in patient setup

This work investigates the use of the tolerance limits on the treatment couch position to detect mistakes in patient positioning and warn users of possible treatment errors. Computer controlled radiotherapy systems use the position of the treatment couch as a surrogate for patient position and a tolerance limit is applied against a planned position. When the couch is out of tolerance a warning is sent to a user to indicate a possible mistake in setup. A tight tolerance may catch all positioning mistakes while as the same time sending too many warnings; while a loose tolerance will not catch all mistakes. We develop a statistical model of the absolute position for the three translational axes of the couch. The couch position for any fraction is considered a random variable x(i). The ideal planned couch position x(p) is unknown before a patient starts treatment and must be estimated from the daily positions x(i). As such x(p) is also a random variable. The tolerance, tol, is applied to the difference between the daily and planned position, d(i) = x(i) - x(p). The di is a linear combination of random variables and therefore the density of di is the convolution of distributions of xi and xp. Tolerance limits are based on the standard deviation of d(i) such that couch positions that are more than 2 standard deviation away are considered out of tolerance. Using this framework we investigate two methods of setting x(p) and tolerance limits. The first, called first day acquire (FDA), is to take couch position on the first day as the planned position. The second is to use the cumulative average (CumA) over previous fractions as the planned position. The standard deviation of d(i) shrinks as more samples are used to determine x(p) and so the tolerance limit shrinks as a function of fraction number when a CumA technique is used. The metrics of sensitivity and specificity were used to characterize the performance of the two methods to correctly identify a couch position as in or out of tolerance. These two methods were tested using simulated and real patient data. Five clinical sites with different indexed immobilization were tested. These were whole brain, head and neck, breast, thorax and prostate. Analysis of the head and neck data shows that it is reasonable to model the daily couch position as a random variable in this treatment site. Using an average couch position for x(p) increased the sensitivity of the couch interlock and reduced the chances of acquiring a couch position that was a statistical outlier. Analysis of variation in couch position for different sites allowed the tolerance limit to be set specifically for a site and immobilization device. The CumA technique was able to increase the sensitivity of detecting out of tolerance positions while shrinking tolerance limits for a treatment course. Making better use of the software interlock on the couch positions could have a positive impact on patient safety and reduce mistakes in treatment delivery.

Impact of an Electronic Chart on the Staff Workload in a Radiation Oncology Department

BACKGROUND

In order to improve the efficiency of patient care, we developed an electronic medical record system, named the Comprehensive Radiation Oncology Management System (C-ROMS). C-ROMS was used together with a commercial record-and-verify system, LANTIS (Siemens Medical Systems Inc., Concord, CA, USA). The impact of the C-ROMS/LANTIS system on the staff workload in the Radiation Oncology Department was quantified and evaluated.

METHODS

Thirty-four breast cancer patients were divided into two groups based on the method of the charting and the delivery of radiation treatment. The paper chart and manual treatment were used for one group, and the C-ROMS/LANTIS for the other. For each group of patients, the workload per patient for each staff group in the department-nursing/clerical staff, simulation staff, dosimetry/physics staff and technologist staff-was measured and compared.

RESULTS

The average total staff workload with the C-ROMS/LANTIS system was 28.2% less than that with the paper chart/manual treatment method. The workloads for nursing/clerical staff, simulation staff and technologist staff were reduced by 85.7, 61.2 and 20.6%, respectively. The workload for dosimetry/physics staff was increased by 28.4%.

CONCLUSION

The C-ROMS/LANTIS system significantly decreased the averaged total staff workload, and thus increased the efficiency of patient care.

Facilitation of radiotherapeutic error by computerized record and verify systems

PURPOSE

To examine the impact of computerized record and verify (R&V) systems on types of radiotherapeutic error.

MATERIALS AND METHODS

Radiation therapy treatment errors reported by therapists at the University of Utah between July 1, 1999 and June 30, 2000 were retrospectively reviewed.

RESULTS

During a 1-year period in which 22,542 external beam radiation therapy treatments were administered, 38 treatment errors (representing 0.17% of external beam treatments administered during this period) were identified and reviewed. Nine cases (0.04% of treatments) representing four types of record and verify (R&V)-related errors were identified, in which the department's R&V system played a contributory role in the treatment error.

CONCLUSIONS

The common denominator among these R&V-related errors was excessive reliance upon the computer system by therapists. R&V systems eliminate some, but not all, pathways of radiotherapeutic error. Although R&V systems have assumed a crucial role in the precise and reproducible delivery of increasingly complex radiation therapy treatments, their inability to eradicate all radiotherapeutic errors coupled with their parallel ability to facilitate certain mistakes mandates vigilance on the part of the radiation therapy team. Radiation therapy treatment procedures must preserve careful oversight of R&V functions to minimize prospects for treatment error.

Evaluation of frequency and type of errors detected by a computerized record and verify system during radiation treatment

BACKGROUND

Computerized record and verify systems (RVS) have been introduced to improve the precision of radiation treatment delivery. These systems prevent the delivery of ionizing radiations when the settings of the treatment machine do not match the intended parameters within some maximal authorized deviation.

PURPOSE

To assess the potential alteration of the frequency of errors associated with the use of RVS during radiation treatment delivery.

MATERIALS AND METHODS

The software of the RVS was altered in order to record the settings actually used for radiation treatment delivery whereas the verification function was suppressed. At the end of the study period, the settings used during daily administration of radiation treatment were compared to the parameters recorded in the RVS using the computer. They were also compared with the planned ones written in the patient treatment chart.

RESULTS

Out of the 147,476 parameters examined during the study period, 678 (0.46%) were set erroneously. At least one error occurred in 628 (3.22%) of the 19,512 treated fields. An erroneous parameter was introduced in the RVS memory in 22 (1.17%) of the 1885 fields.

CONCLUSIONS

RVS has the potential to improve precision of radiation treatment delivery by detecting a significant number of setting errors. However, excessive confidence in RVS could lead to repeated errors as there is a potential for the entry of erroneous parameters into the RVS memory.

The impact of treatment complexity and computer-control delivery technology on treatment delivery errors

PURPOSE

To analyze treatment delivery errors for three-dimensional (3D) conformal therapy performed at various levels of treatment delivery automation and complexity, ranging from manual field setup to virtually complete computer-controlled treatment delivery using a computer-controlled conformal radiotherapy system (CCRS).

METHODS AND MATERIALS

All treatment delivery errors which occurred in our department during a 15-month period were analyzed. Approximately 34,000 treatment sessions (114,000 individual treatment segments [ports]) on four treatment machines were studied. All treatment delivery errors logged by treatment therapists or quality assurance reviews (152 in all) were analyzed. Machines "M1" and "M2" were operated in a standard manual setup mode, with no record and verify system (R/V). MLC machines "M3" and "M4" treated patients under the control of the CCRS system, which (1) downloads the treatment delivery plan from the planning system; (2) performs some (or all) of the machine set up and treatment delivery for each field; (3) monitors treatment delivery; (4) records all treatment parameters; and (5) notes exceptions to the electronically-prescribed plan. Complete external computer control is not available on M3; therefore, it uses as many CCRS features as possible, while M4 operates completely under CCRS control and performs semi-automated and automated multi-segment intensity modulated treatments. Analysis of treatment complexity was based on numbers of fields, individual segments, nonaxial and noncoplanar plans, multisegment intensity modulation, and pseudoisocentric treatments studied for a 6-month period (505 patients) concurrent with the period in which the delivery errors were obtained. Treatment delivery time was obtained from the computerized scheduling system (for manual treatments) or from CCRS system logs. Treatment therapists rotate among the machines; therefore, this analysis does not depend on fixed therapist staff on particular machines.

RESULTS

The overall reported error rate (all treatments, machines) was 0.13% per segment, or 0.44% per treatment session. The rate (per machine) depended on automation and plan complexity. The error rates per segment for machines M1 through M4 were 0.16%, 0.27%, 0.12%, 0.05%, respectively, while plan complexity increased from M1 up to machine M4. Machine M4 (the most complex plans and automation) had the lowest error rate. The error rate decreased with increasing automation in spite of increasing plan complexity, while for the manual machines, the error rate increased with complexity. Note that the real error rates on the two manual machines are likely to be higher than shown here (due to unnoticed and/or unreported errors), while (particularly on M4) virtually all random treatment delivery errors were noted by the CCRS system and related QA checks (including routine checks of machine and table readouts for each treatment). Treatment delivery times averaged from 14 min to 23 min per plan, and depended on the number of segments/plan, although this analysis is complicated by other factors.

CONCLUSION

Use of a sophisticated computer-controlled delivery system for routine patient treatments with complex 3D conformal plans has led to a decrease in treatment delivery errors, while at the same time allowing delivery of increasingly complex and sophisticated conformal plans with little increase in treatment time. With renewed vigilance for the possibility of systematic problems, it is clear that use of complete and integrated computer-controlled delivery systems can provide improvements in treatment delivery, since more complex plans can be delivered with fewer errors, and without increasing treatment time.

Integration of radiotherapy planning systems and radiotherapy treatment equipment: 11 years experience

PURPOSE

We have investigated the requirements, design, implementation, and operation of a computer-controlled medical accelerator with multileaf collimator (MLC), integrated with a radiation treatment-planning system (RTPS), and we report on the performance, benefits, and lessons learned from this experience.

METHODS AND MATERIALS

In 1984 the University of Washington installed a computer-controlled radiation therapy machine (the Clinical Neutron Therapy System, or CNTS) with a multileaf collimator. Since the beginning of operation the control system computer has been connected by commercially available network hardware and software to three generations of radiation treatment-planning systems. Semiautomated setup and completely computerized check and confirm were incorporated into the system from the beginning of clinical operation in 1984. The system cannot deliver a patient treatment without a computer-prepared treatment plan.

RESULTS

The CNTS has been in use for routine patient treatments for over 11 years. The cost of the network connection and software was an insignificant fraction of the facility cost. Operation has been efficient and reliable. Of the 441 machine-related session reschedulings (out of 18,432 sessions total) during the past 9 years, only 20 were due to problems with data transfer between the RTPS and CNTS, associated primarily with two incidents. Close integration with the treatment-planning system allows complex treatments to be delivered. Dramatic evolution of the departmental treatment-planning system has not required any changes or redesign of either the accelerator control system or the network connection.

CONCLUSIONS

Our experience shows that a large degree of automation is possible with reasonable effort, by using well-known software and hardware design strategies. The lessons we have learned from this can be carried over into photon therapy now that photon accelerators with MLC facilities are commercially available.

Development and use of a computer system in a radiotherapy department: SISGRAD

SISGRAD, the interactive computer system of the Antoine-Lacassagne Cancer Center Radiotherapy Department, has been operational since January 1982. It completes the computerized dosimetry system installed several years earlier and is fully integrated with the institution's central network. SISGRAD is in charge of surveillance of the radiotherapy treatments given by the Center's three radiotherapy units (1400 patients per year); it is also used for administrative purposes in the Department and physically connects all of the Department's operating stations. SISGRAD consists of a series of microcomputers connected to a common mass memory; each microcomputer is used as an intelligent console. SISGRAD was developed to guarantee that the treatments comply with prescriptions, to supply extemporaneous dosimetric data, to improve administrative work, and to supply banks with data for statistical analysis and research. SISGRAD actively intervenes to guarantee treatment quality and helps to improve therapy-related security factors. The present text describes the results of clinical use over a 4-year period. The consequences of integration of the system within the Department are analyzed, with special emphasis being placed on SISGRAD's role in the prevention and detection of errors in treatment prescription and delivery.

Clinical experience with a computerized record and verify system

To improve the quality of patient care by detecting and preventing many types of treatment mistakes, we have implemented a computerized system for recording and verifying external beam radiation treatments on our therapy machines. It inhibits the radiation beam if treatment machine settings do not agree with prescribed values to within maximum permissible deviations (tolerances). The tolerances are determined from experience and adjusted when necessary to make the system more effective and less susceptible to "false alarms." The system uses a common data base for all treatment machines. As a result, it permits statistical analysis and generation of reports based on data encompassing the entire patient population as well as verification of treatments of patients transferred from one machine to another. Reports of verification failures reveal patterns of mistakes. Knowing these, attempts can be made to reduce the frequency of verification failures. "Significant" mistakes that were prevented are extracted by treatment planning personnel from these reports. Analysis of data indicates a rate of approximately 150 "significant" mistakes detected and prevented per machine per year, representing 1.0% of all fields treated. We present and discuss our experiences with the system and with the frequency, patterns, and significance of verification failures. We selected a few of the patients for whose treatments significant set-up mistakes were made, and were detected and prevented by the Record and Verify System. We include discussions of the overall effect these mistakes would have had on dose distribution had they not been prevented.