Is Cementless Total Knee Arthroplasty Safe in Women Over 75 Y of Age?

BACKGROUND: Cementless total knee arthroplasty (TKA) is the subject of renewed interest. Previous concerns about survivorship have been addressed and there is an appeal in terms of biological fixation and surgical efficiency. However, even surgeon advocates have concerns about the risk of marked subsidence when using this technology in older patients at risk for osteoporosis. METHODS: This was a retrospective analysis of 1,000 consecutive fully cementless mobile bearing TKAs performed at a single institution on women over 75 years of age who had postoperative and 1-year x-rays. The primary outcome was the incidence of subsidence. RESULTS: There were three asymptomatic cases with definite subsidence and change in alignment. In a fourth symptomatic case, the femoral component subsided into varus and the tibia into valgus, thus maintaining alignment which facilitated nonoperative treatment in a 92-year-old. Overall, at 1 year, there were two- liner revisions for infection without recurrence. Five patients had further surgery, of which three were washouts and two were for periprosthetic fractures sustained postoperatively within 1 year. Seven patients had further anesthesia, of which five were manipulations and two were nonrecurrent closed reductions for spinouts. CONCLUSION: Cementless TKA did not have a high risk of subsidence in this at-risk population. In the hands of experienced surgeons, these procedures can be used safely irrespective of bone quality.

Hand dominance and experience improve bimanual performance on arthroscopic simulator task.

PURPOSE: The aim of this study was to identify if experience in arthroscopy confers ambidexterity to the operator and the role of baseline characteristics in arthroscopic simulator performance. METHODS: A prospective comparative study was carried out across four regional Orthopaedic training centres. Participants were divided into novice, intermediate or experienced groups based on arthroscopic experience. Baseline demographics including age, sex, handedness, and gaming history were also collected. Following familiarisation with the procedure, participants were asked to complete a simulated task requiring bimanual control consisting of visualisation with camera control and manipulation of highlighted objects using a grasping instrument. One attempt using camera control and grasping accuracy per hand was performed by each participant, with scores for each hand collected for analysis. Performance scores for camera alignment, camera path length, grasper path length and grasping efficiency were collected. Time taken to completion was also noted for each attempt. RESULTS: Fifty-six participants were recruited to the study. A significant difference in grasping efficiency between groups in the dominant hand was demonstrated (p = 0.013). Novices demonstrated laterality with superior performance in grasping efficiency in the dominant hand (p = 0.001). No significant difference was noted between dominant and non-dominant hand performance in the experienced group. CONCLUSION: Arthroscopic simulation-based training is a valuable learning tool for orthopaedic training. This study demonstrated that experienced orthopaedic surgeons have a greater degree of ambidexterity than intermediate or novice groups, hypothesised by authors to be conferred through conventional orthopaedic training. Dedicated bimanual control tasks to reduce laterality in trainees should be incorporated in simulated surgical curricula. LEVEL OF EVIDENCE: III.

Regional trauma patterns during the COVID-19 pandemic.

BACKGROUND: The current pandemic has impacted heavily on health systems, making unprecedented demands on resources, and forcing reconfiguration of services. Trauma and orthopaedic units have cancelled elective surgery, moved to virtual based clinics and have been forced to reconsider the provision of trauma. Our national elective orthopaedic centre has been re-designated as a trauma centre to allow tertiary centres re-direct triaged trauma. Many governments, as part of their COVID-19 management, have significantly restricted activity of the general population. We proposed that trauma patterns would change alongside these changes and maintaining existing standards of treatment would require dedicated planning and structures. METHODS: Referrals over a six-week period (March 15th to April 30th) were retrospectively reviewed. Data was collected directly from our referral database and a database populated. Analysis was performed to assess trauma volume, aetiology, and changes in trends. RESULTS: There were one hundred and fifty-nine referrals from three individual hospitals within the timeframe. Mean age of patient's referred was 55 (range17-92). Males accounted for 45% of cases. F&A injuries were the most common (32%), followed by H&W (28%), UL (17%), H&F (16%) and K&T (7%). In comparison to the corresponding time-period in 2019, trauma theatre activity reduced by almost one half (45.3%) CONCLUSION: The majority of trauma referred to our Dublin based centre during COVID-19 related population restrictions appears to be home based and trauma volumes have decreased. Significant reductions are apparent in work and sport related injuries suggestive of compliance with COVID-19 activity guidelines. Maintaining existing standards of treatment requires dedicated planning.

Crisis change management during COVID-19 in the elective orthopaedic hospital: Easing the trauma burden of acute hospitals.

INTRODUCTION: With the emergence of the 2019 novel coronavirus and its resulting pandemic status in March 2020 all routine elective orthopaedic surgery was cancelled in our institution. The developing picture in Italy, of acute hospitals becoming overwhelmed with treating patients suffering with severe and life-threatening symptoms from the disease, prompted the orthopaedic surgeons to formulate a plan to transfer trauma patients requiring surgery to the elective hospital to unburden the acute hospital system. METHODS: Under the threat of this pandemic; protocols and algorithms were established for referral, acceptance and care of trauma patients from acute hospitals in the region. Each day, as new guidance on COVID-19 emerged, our process and algorithms were adjusted to reflect pertinent change. RESULTS: The screening of all patients referred, worked well in keeping our hospital "COVID-free" with respect to patients undergoing operations. An upward trend in cases referred reflected the decreased capacity in the acute hospitals due to rising cases of COVID-19 within the hospital network. During the first 7 weeks of the pandemic 308 operations were performed, (31.1% upper limb, 33.4% lower limb, 4.1% spine, 14.1% urgent elective, 17.4% plastic surgery cases). Regular review and audit of the activity in the hospital as well as communication with the referring teams enabled appropriate planning to accommodate the increase in case-mix as the need arose. DISCUSSION: This paper details the steps that were taken in planning for such a change in management specific to the orthopaedic surgery setting and the lessons learnt during this process. The success of the development of this pathway was facilitated by clear communication channels, flexibility to adapt to changing process and feedback from all stakeholders. The implementation of this pathway allowed the unburdening of acute hospitals dealing with the pandemic that was steadily reducing access to operating theatres and anaesthetic resources.

Peri-operative outcomes for ORIF of acetabular fracture in the elderly: Comparison with displaced intracapsular hip fractures in a national pelvic and acetabular referral centre over 5 years.

INTRODUCTION: The increasing incidence of acetabular fractures in the elderly and the fracture complexity seen in this cohort represents one of the greatest challenges faced by trauma orthopaedic surgeons today. There are no formal guidelines of best practice in the treatment of these patients. Management options vary from non-operative, acute ORIF, and/or total joint replacement. Although surgical intervention allows for earlier mobilization and avoidance of the complications of prolonged bedrest, the patients ability to tolerate what is often major surgery is always of concern. This is in stark contrast to intracapsular hip fractures, (a fracture within the same joint), where acute surgery is recommended in virtually all cases. OBJECTIVES: This study was undertaken to evaluate the peri-operative outcomes for geriatric patients undergoing acetabular ORIF and hemiarthroplasty to assess if there is a significant difference in early outcome parameters. DESIGN: This is a retrospective case-control study. SETTING: This study was performed in the National Centre for Pelvic and Acetabular surgery. PATIENTS: 42 age- and sex-matched patients with comparable ASA grades were included in each arm of the study. Patient selection in the acetabular ORIF group was consecutive patients managed operatively in the centre during the period 2010-2015. The selection for the hemiarthroplasty group was by random selection of age- and sex-matched patients undergoing hemiarthroplasty during the same period. MAIN OUTCOME MEASUREMENTS: The primary outcomes that were proposed prior to the study being performed was perioperative mortality and post-op complications. Secondary outcomes were operating times, blood loss and need for ICU admission. RESULTS: A significant difference between the two cohorts was observed with operative times, blood loss, need for transfusion, and need for ICU admission, all higher in the acetabular ORIF group. There was no significant difference in mortality or post-op infection. CONCLUSIONS: Our paper supports the concept that acute ORIF of acetabular fractures, with appropriate peri-operative support, can be undertaken safely. There is no difference in the major peri-operative outcomes of mortality or infection when compared with hip fracture patients requiring hemiarthroplasty.

Comparison of measured electron energy spectra for six matched, radiotherapy accelerators.

This study compares energy spectra of the multiple electron beams of individual radiotherapy machines, as well as the sets of spectra across multiple matched machines. Also, energy spectrum metrics are compared with central-axis percent depth-dose (PDD) metrics. METHODS: A lightweight, permanent magnet spectrometer was used to measure energy spectra for seven electron beams (7-20 MeV) on six matched Elekta Infinity accelerators with the MLCi2 treatment head. PDD measurements in the distal falloff region provided R50 and R80-20 metrics in Plastic Water® , which correlated with energy spectrum metrics, peak mean energy (PME) and full-width at half maximum (FWHM). RESULTS: Visual inspection of energy spectra and their metrics showed whether beams on single machines were properly tuned, i.e., FWHM is expected to increase and peak height decrease monotonically with increased PME. Also, PME spacings are expected to be approximately equal for 7-13 MeV beams (0.5-cm R90 spacing) and for 13-16 MeV beams (1.0-cm R90 spacing). Most machines failed these expectations, presumably due to tolerances for initial beam matching (0.05 cm in R90 ; 0.10 cm in R80-20 ) and ongoing quality assurance (0.2 cm in R50 ). Also, comparison of energy spectra or metrics for a single beam energy (six machines) showed outlying spectra. These variations in energy spectra provided ample data spread for correlating PME and FWHM with PDD metrics. Least-squares fits showed that R50 and R80-20 varied linearly and supralinearly with PME, respectively; however, both suggested a secondary dependence on FWHM. Hence, PME and FWHM could serve as surrogates for R50 and R80-20 for beam tuning by the accelerator engineer, possibly being more sensitive (e.g., 0.1 cm in R80-20 corresponded to 2.0 MeV in FWHM). CONCLUSIONS: Results of this study suggest a lightweight, permanent magnet spectrometer could be a useful beam-tuning instrument for the accelerator engineer to (a) match electron beams prior to beam commissioning, (b) tune electron beams for the duration of their clinical use, and (c) provide estimates of PDD metrics following machine maintenance. However, a real-time version of the spectrometer is needed to be practical.

A dosimetric comparison of copper and Cerrobend electron inserts.

The purpose of this work was to evaluate differences in dose resulting from the use of copper aperture inserts compared to lead-alloy (Cerrobend) aperture inserts for electron beam therapy. Specifically, this study examines if copper aperture inserts can be used clinically with the same commissioning data measured using lead-alloy aperture inserts. The copper inserts were acquired from .decimal, LLC and matching lead-alloy, Cerrobend inserts were constructed in-house for 32 com-binations of nine square insert field sizes (2 × 2 to 20 × 20 cm2) and five applicator sizes (6 × 6 to 25 × 25 cm2). Percent depth-dose and off-axis relative dose profiles were measured using an electron diode in water for select copper and Cerrobend inserts for a subset of applicators (6 × 6, 10 × 10, 25 × 25 cm2) and energies (6, 12, 20 MeV) at 100 and 110 cm source-to-surface distances (SSD) on a Varian Clinac 21EX accelerator. Dose outputs were measured for all field size-insert combina-tions and five available energies (6-20 MeV) at 100 cm SSD and for a smaller subset at 110 cm SSD. Using these data, 2D planar absolute dose distributions were generated and compared. Criteria for agreement were ± 2% of maximum dose or 1 mm distance-to-agreement for 99% of points. A gamma analysis of the beam dosimetry showed 94 of 96 combinations of insert size, applicator, energy, and SSD were within the 2%/1 mm criteria for > 99% of points. Outside the field, copper inserts showed less bremsstrahlung dose under the insert compared to Cerrobend (greatest difference was 2.5% at 20 MeV and 100 cm SSD). This effect was most prominent at the highest energies for combinations of large applicators with small field sizes, causing some gamma analysis failures. Inside the field, more electrons scattered from the collimator edge of copper compared to Cerrobend, resulting in an increased dose at the field edge for copper at shallow depths (greatest increase was 1% at 20 MeV and 100 cm SSD). Dose differences decreased as the SSD increased, with no gamma failures at 110 cm SSD. Inserts for field sizes ≥ 6 × 6 cm2 at any energy, or for small fields (≤ 4 × 4 cm2) at energies < 20 MeV, showed dosimetric differences less than 2%/1 mm for more than 99% of points. All areas of comparison criteria failures were from lower out-of-field dose under copper inserts due to a reduction in bremsstrahlung production, which is clinically beneficial in reducing dose to healthy tissue outside of the planned treatment volume. All field size-applicator size-energy combinations passed 3%/1 mm criteria for 100% of points. Therefore, it should be clinically acceptable to utilize copper insets with dose distributions measured with Cerrobend inserts for treatment planning dose calculations and monitor unit calculations.

Experience with botulinum toxin therapy for axillary hyperhidrosis and comparison to modelled data for endoscopic thoracic sympathectomy - A quality of life and cost effectiveness analysis.

AIM: To estimate cost-effectiveness of botulinum toxin therapy for axillary hyperhidrosis compared to the standard surgical intervention of endoscopic thoracic sympathectomy (ETS). METHODS: The validated dermatology life quality index questionnaire was given to patients attending for treatment over a 4 month period, to assess their quality of life (QoL) over the preceding week (n = 44). Follow-up was performed 4-6 weeks later by telephone using the same questionnaire to validate the effectiveness of the treatment. The duration of effect of the botulinum toxin treatment was also recorded and this data was used as the basis for cost effectiveness analysis. Using HIPE data, the baseline cost for single intervention using botulinum toxin and ETS was retrieved. Using figures provided by HIPE and expert opinion of the costs of complications, a stochastic model for 10,000 patients was used to evaluate the total costs for ETS including the complications. RESULTS: The results from the QoL analysis show that botulinum toxin therapy is a successful therapy for improvement of symptoms. It was revealed that the mean interval before recurrence of original symptoms after botulinum toxin therapy was 5.6 months. The baseline cost for both treatments are €389 for botulinum toxin and €9389 for uncomplicated ETS. The stochastic model yields a mean cost of €11,390 for ETS including complications. CONCLUSIONS: Treatments reached cost equivalence after 13.3 years. However, given the efficacy of the botulinum toxin therapy and the low risk we propose that botulinum toxin therapy for hyperhidrosis should be considered the gold standard.

Intra- and intervariability in beam data commissioning among water phantom scanning systems.

Accurate beam data acquisition during commissioning is essential for modeling the treatment planning system and dose calculation in radiotherapy. Although currently several commercial scanning systems are available, there is no report that compared the differences among the systems because most institutions do not acquire several scanning systems due to the high cost, storage space, and infrequent usage. In this report, we demonstrate the intra- and intervariability of beam profiles measured with four commercial scanning systems. During a recent educational and training workshop, four different vendors of beam scanning water phantoms were invited to demonstrate the operation and data collection of their systems. Systems were set up utilizing vendor-recommended protocols and were operated with a senior physicist, who was assigned as an instructor along with vendor. During the training sessions, each group was asked to measure beam parameters, and the intravariability in percent depth dose (PDD). At the end of the day, the profile of one linear accelerator was measured with each system to evaluate intervariability. Relatively very small (SD < 0.12%) intervariability in PDD was observed among four systems at a region deeper than peak (1.5 cm). All systems showed almost identical profiles. At the area within 80% of radiation field, the average, and maximum differences were within ± 0.35% and 0.80%, respectively, compared to arbitrarily chosen IBA system as reference. In the penumbrae region, the distance to agreement (DTA) of the region where dose difference exceed ± 1% was less than 1 mm. Repeated PDD measurement showed small intravariability with SD < 0.5%, although large SD was observed in the buildup region. All four water phantom scanning systems demonstrated adequate accuracy for beam data collection (i.e., within 1% of dose difference or 1 mm of DTA among each other). It is concluded that every system is capable of acquiring accurate beam. Thus the selection of a water scanning system should be based on institutional comfort, personal preference of software and hardware, and financial consideration.

Medical Physics Residency Consortium: collaborative endeavors to meet the ABR 2014 certification requirements.

In 2009, Mary Bird Perkins Cancer Center (MBPCC) established a Radiation Oncology Physics Residency Program to provide opportunities for medical physics residency training to MS and PhD graduates of the CAMPEP-accredited Louisiana State University (LSU)-MBPCC Medical Physics Graduate Program. The LSU-MBPCC Program graduates approximately six students yearly, which equates to a need for up to twelve residency positions in a two-year program. To address this need for residency positions, MBPCC has expanded its Program by developing a Consortium consisting of partnerships with medical physics groups located at other nearby clinical institutions. The consortium model offers the residents exposure to a broader range of procedures, technology, and faculty than available at the individual institutions. The Consortium institutions have shown a great deal of support from their medical physics groups and administrations in developing these partnerships. Details of these partnerships are specified within affiliation agreements between MBPCC and each participating institution. All partner sites began resident training in 2011. The Consortium is a network of for-profit, nonprofit, academic, community, and private entities. We feel that these types of collaborative endeavors will be required nationally to reach the number of residency positions needed to meet the 2014 ABR certification requirements and to maintain graduate medical physics training programs.

Comparison of action levels for patient-specific quality assurance of intensity modulated radiation therapy and volumetric modulated arc therapy treatments.

PURPOSE: To perform a comprehensive and systematic comparison of fixed-beam IMRT and volumetric modulated arc therapy (VMAT) patient-specific QA measurements for a common set of geometries using typical measurement methods. METHODS: Fixed-beam IMRT and VMAT plans were constructed for structure set geometries provided by AAPM Task Group 119. The plans were repeatedly delivered across multiple measurement sessions, and the resulting dose distributions were measured with (1) radiochromic film and ionization chamber and (2) a commercial two-dimensional diode array. The resulting QA measurements from each delivery technique were then analyzed, compared, and tested for statistically significant differences. RESULTS: Although differences were noted between QA results for some plans, neither modality showed consistently better agreement of measured and planned doses: of the 22 comparisons, IMRT showed better QA results in 11 cases, and VMAT showed better QA results in 11 cases. No statistically significant differences (p < 0.05) between IMRT and VMAT QA results were found for point doses measured with an ionization chamber, planar doses measured with radiochromic film, or planar doses measured with a two-dimensional diode array. CONCLUSIONS: These results suggest that it is appropriate to apply patient-specific QA action levels derived from fixed-beam IMRT to VMAT.

Knowledge of face masks and attitudes to re-sterilisation among healthcare workers.

INTRODUCTION: COVID-19 was declared a pandemic in March 2020. With the sudden surge in demand for personal protective equipment (PPE), significant concerns regarding the ongoing availability emerged. One solution proposed is re-sterilisation of respirator masks and this has been commenced in some parts of the world. On review of the literature, very little is documented regarding the knowledge of masks and the attitudes of healthcare workers towards using re-sterilised masks. METHODS: A comprehensive questionnaire was used to assess general knowledge and attitudes around facemasks and respirators. RESULTS: There were 190 respondents. There were significant gaps in knowledge and understanding of when particular face masks should be worn. One-third had significant concerns about ongoing availability. One-third had concerns about the quality of the masks as the pandemic continued. Only 10% of respondents underwent formal face-fitting. Eighty percent of respondents stated they would wear a re-sterilised mask. A further 15% would use a re-sterilised mask but required certain reassurances. Five percent of our respondents would not use a re-sterilised mask under any circumstances. DISCUSSION: Ensuring an adequate understanding of face masks is crucial among healthcare workers (HCWs) and this study highlights a need for further education. It also demonstrates a general acceptability among HCWs towards the use of re-sterilised face masks.

Revision of total knee replacement (TKR) secondary to raised cobalt levels: should this be considered in the painful TKR patient?

A 63-year-old woman was referred to the specialised knee revision clinic with ongoing knee pain after total knee replacement. She incidentally had cobalt and chromium levels measured. These were seen to be elevated. Comprehensive assessment and investigation did not identify any other source of cobalt or chromium. Aseptic loosening of the knee was diagnosed, and the knee was revised. At the time of surgery, the tissue was seen to be darkened consistent with metallosis. Multiple samples excluded infection on extended cultures. Aspirated fluid showed that periprosthetic fluid had elevated cobalt levels. The knee was successfully revised with good symptomatic outcome and significantly, over the course of several months post-revision, the cobalt and chromium levels returned to normal.

Independent calculation of dose from a helical TomoTherapy unit.

A new calculation algorithm has been developed for independently verifying doses calculated by the TomoTherapy Hi.Art treatment planning system (TPS). The algorithm is designed to confirm the dose to a point in a high dose, low dose-gradient region. Patient data used by the algorithm include the radiological depth to the point for each projection angle and the treatment sinogram file controlling the leaf opening time for each projection. The algorithm uses common dosimetric functions [tissue phantom ratio (TPR) and output factor (Scp)] for the central axis combined with lateral and longitudinal beam profile data to quantify the off-axis dose dependence. Machine data for the dosimetric functions were measured on the Hi.Art machine and simulated using the TPS. Point dose calculations were made for several test phantoms and for 97 patient treatment plans using the simulated machine data. Comparisons with TPS-predicted point doses for the phantom treatment plans demonstrated agreement within 2% for both on-axis and off-axis planning target volumes (PTVs). Comparisons with TPS-predicted point doses for the patient treatment plans also showed good agreement. For calculations at sites other than lung and superficial PTVs, agreement between the calculations was within 2% for 94% of the patient calculations (64 of 68). Calculations within lung and superficial PTVs overestimated the dose by an average of 3.1% (sigma=2.4%) and 3.2% (sigma=2.2%), respectively. Systematic errors within lung are probably due to the weakness of the algorithm in correcting for missing tissue and/or tissue density heterogeneities. Errors encountered within superficial PTVs probably result from the algorithm overestimating the scatter dose within the patient. Our results demonstrate that for the majority of cases, the algorithm could be used without further refinement to independently verify patient treatment plans.

Total hip replacement-the cause of failure in patients under 50 years old?

AIM: To establish the mode of failure of primary total hip replacement in patients under 50 years old. METHODS: A total of 1062 revision total hip arthroplasties were performed over a 5-year period, with 146 on patients under 50 years old. These were subdivided into early (< 5 years) and late (> 5 years) failures from the index procedure. RESULTS: The commonest mechanism of failure was aseptic loosening (42.3%) followed by metal-on-metal failure (15.8%), infection (14.4%) and instability (9.6%). The commonest cause of early revision surgery was due to metal-on-metal failure (27.8%) followed by aseptic loosening (19.7%) and infection (18.4%). In the late revision group, the main cause of failure was aseptic loosening (64%) and infection (10.7%). CONCLUSION: The changing trend of early revision due to metal-on-metal failure is important to recognise. Continuous review of the mechanism of primary total hip replacement failure is necessary to ensure the best patient outcome and maximise implant survivorship.

Helical tomotherapy for parotid gland tumors.

PURPOSE: To investigate helical tomotherapy (HT) intensity-modulated radiotherapy (IMRT) as a postoperative treatment for parotid gland tumors. METHODS AND MATERIALS: Helical tomotherapy plans were developed for 4 patients previously treated with segmental multileaf collimator (SMLC) IMRT. A primary planning target volume (PTV64) and two secondary PTVs (PTV60, PTV54) were defined. The clinical goals from the SMLC plans were applied as closely as possible to the HT planning. The SMLC plans included bolus, whereas HT plans did not. RESULTS: In general, the HT plans showed better target coverage and target dose homogeneity. The minimum doses to the desired coverage volume were greater, on average, in the HT plans for all the targets. Minimum PTV doses were larger, on average, in the HT plans by 4.6 Gy (p = 0.03), 4.8 Gy (p = 0.06), and 4.9 Gy (p = 0.06) for PTV64, PTV60, and PTV54, respectively. Maximum PTV doses were smaller, on average, by 2.9 Gy (p = 0.23), 3.2 Gy (p = 0.02), and 3.6 Gy (p = 0.03) for PTV64, PTV60, and PTV54, respectively. Average dose homogeneity index was statistically smaller in the HT plans, and conformity index was larger for PTV64 in 3 patients. Tumor control probabilities were higher for 3 of the 4 patients. Sparing of normal structures was comparable for the two techniques. There were no significant differences between the normal tissue complication probabilities for the HT and SMLC plans. CONCLUSIONS: Helical tomotherapy treatment plans were comparable to or slightly better than SMLC plans. Helical tomotherapy is an effective alternative to SMLC IMRT for treatment of parotid tumors.

A method for evaluating quality assurance needs in radiation therapy.

The increasing complexity of modern radiation therapy planning and delivery techniques challenges traditional prescriptive quality control and quality assurance programs that ensure safety and reliability of treatment planning and delivery systems under all clinical scenarios. Until now quality management (QM) guidelines published by concerned organizations (e.g., American Association of Physicists in Medicine [AAPM], European Society for Therapeutic Radiology and Oncology [ESTRO], International Atomic Energy Agency [IAEA]) have focused on monitoring functional performance of radiotherapy equipment by measurable parameters, with tolerances set at strict but achievable values. In the modern environment, however, the number and sophistication of possible tests and measurements have increased dramatically. There is a need to prioritize QM activities in a way that will strike a balance between being reasonably achievable and optimally beneficial to patients. A systematic understanding of possible errors over the course of a radiation therapy treatment and the potential clinical impact of each is needed to direct limited resources in such a way to produce maximal benefit to the quality of patient care. Task Group 100 of the AAPM has taken a broad view of these issues and is developing a framework for designing QM activities, and hence allocating resources, based on estimates of clinical outcome, risk assessment, and failure modes. The report will provide guidelines on risk assessment approaches with emphasis on failure mode and effect analysis (FMEA) and an achievable QM program based on risk analysis. Examples of FMEA to intensity-modulated radiation therapy and high-dose-rate brachytherapy are presented. Recommendations on how to apply this new approach to individual clinics and further research and development will also be discussed.

Measurement of superficial dose from a static tomotherapy beam.

Superficial doses were measured for static TomoTherapy Hi-Art beams for normal and oblique incidence. Dose was measured at depths < or = 2 cm along the central axis of 40 x 5 cm2 and 40 x 2.5 cm2 beams at normal incidence for source to detector distances (SDDs) of 55, 70, and 85 cm. Measurements were also made at depths normal to the phantom surface for the same beams at oblique angles of 30 degrees, 45 degrees, 60 degrees, 75 degrees, and 83 degrees from the normal. Data were collected with a Gammex/RMI model 449 parallel-plate chamber embedded in a solid water phantom and with LiF thermoluminescent dosimeters (TLDs) in the form of powder. For comparison, measurements were made on a conventional 6 MV beam (Varian Clinac 2100C) at normal incidence and at an oblique angle of 60 degrees from the normal. TomoTherapy surface dose varied with the distance from the source and the angle of incidence. For normal incidence, surface dose increased from 0.16 to 0.43 cGy/MU as the distance from the source decreased from 85 to 55 cm for the 40 x 5 cm2 field and increased from 0.12 to 0.32 cGy/MU for the 40 x 2.5 cm2 field. As the angle of incidence increased from 0 degrees to 83 degrees, surface dose increased from 0.24 to 0.63 cGy/MU for the 40 x 5 cm2 field and from 0.18 to 0.58 cGy/MU for the 40 x 2.5 cm2 field. For normal incidence at 55 cm SDD, the surface dose relative to the dose at d(max) for the 40 x 5 cm2 TomoTherapy Hi-Art beam was 31% less than that from a conventional, flattening filter based linear accelerator. These data should prove useful in accessing the accuracy of the TomoTherapy treatment planning system to predict the dose at superficial depths for a static beam delivery.

Accuracy of TomoTherapy treatments for superficial target volumes.

Helical tomotherapy is a technique for delivering intensity modulated radiation therapy treatments using a continuously rotating linac. In this approach, fan beams exiting the linac are dynamically modulated in synchrony with the motion of the gantry and couch. Helical IMRT deliveries have been applied to treating surface lesions, and the purpose of this study was to evaluate the accuracy of dose calculated by the TomoTherapy HiArt treatment planning system for superficial planning target volumes (PTVs). TomoTherapy treatment plans were developed for three superficial PTVs (2-, 4-, and 6-cm deep radially by 90 degrees azimuthally by 4-cm longitudinally) contoured on a 27-cm diameter cylindrical white opaque, high-impact polystyrene phantom. The phantom included removable transverse and sagittal film cassettes that contained bare Kodak EDR2 films cut such that their edges matched the phantom surface (+/-0.05 cm). The phantom was aligned to the machine's isocenter (+/-0.05 cm) and was irradiated according to the treatment plans. Films were scanned with a Vidar film digitizer, and optical densities were converted to dose using a calibration determined from a 6 MV perpendicular film exposure. This perpendicular calibration required that axial film doses (parallel irradiation) be scaled by 1.02 so that mid-arc depth doses matched those measured in the sagittal plane (perpendicular irradiation). All film readings were scaled by 0.935 to correct for over-response due to phantom Cerenkov light. Measured dose distributions were registered to calculated ones and compared. Calculated doses overpredicted measured doses by as much as 9.5% of the prescribed dose at depths less than 1 cm. At depths greater than 1 cm, calculated dose distributions showed agreement to measurement within 5% in the high-dose region and within 0.2 cm distance-to-agreement in the dose falloff regions. In the low-dose region posterior to the PTVs (<10% of the prescribed dose), the dose algorithm underpredicted the dose by 1%-2% of the prescribed dose. Clinically, it is recommended that 1 cm of bolus be used on the surface to ensure that cancerous tissues less than 1 cm depth are not underdosed.

The report of Task Group 100 of the AAPM: Application of risk analysis methods to radiation therapy quality management.

The increasing complexity of modern radiation therapy planning and delivery challenges traditional prescriptive quality management (QM) methods, such as many of those included in guidelines published by organizations such as the AAPM, ASTRO, ACR, ESTRO, and IAEA. These prescriptive guidelines have traditionally focused on monitoring all aspects of the functional performance of radiotherapy (RT) equipment by comparing parameters against tolerances set at strict but achievable values. Many errors that occur in radiation oncology are not due to failures in devices and software; rather they are failures in workflow and process. A systematic understanding of the likelihood and clinical impact of possible failures throughout a course of radiotherapy is needed to direct limit QM resources efficiently to produce maximum safety and quality of patient care. Task Group 100 of the AAPM has taken a broad view of these issues and has developed a framework for designing QM activities, based on estimates of the probability of identified failures and their clinical outcome through the RT planning and delivery process. The Task Group has chosen a specific radiotherapy process required for "intensity modulated radiation therapy (IMRT)" as a case study. The goal of this work is to apply modern risk-based analysis techniques to this complex RT process in order to demonstrate to the RT community that such techniques may help identify more effective and efficient ways to enhance the safety and quality of our treatment processes. The task group generated by consensus an example quality management program strategy for the IMRT process performed at the institution of one of the authors. This report describes the methodology and nomenclature developed, presents the process maps, FMEAs, fault trees, and QM programs developed, and makes suggestions on how this information could be used in the clinic. The development and implementation of risk-assessment techniques will make radiation therapy safer and more efficient.