Search

Background: There is continuing debate about the ideal philosophy for component alignment in TKA. However, there are limited long-term functional and radiographic data on randomized comparisons of kinematic alignment versus mechanical alignment., Questions/purposes: We present the 10-year follow-up findings of a single-center, multisurgeon randomized controlled trial (RCT) comparing these two alignment philosophies in terms of the following questions: (1) Is there a difference in PROM scores? (2) Is there a difference in survivorship free from revision or reoperation for any cause? (3) Is there a difference in survivorship free from radiographic loosening?, Methods: Ninety-nine patients undergoing primary TKA for osteoarthritis were randomized to either the mechanical alignment (n = 50) or kinematic alignment (n = 49) group. Eligibility for the study was patients undergoing unilateral TKA for osteoarthritis who were suitable for a cruciate-retaining TKA and could undergo MRI. Patients who had previous osteotomy, coronal alignment > 15° from neutral, a fixed flexion deformity > 15°, or instability whereby constrained components were being considered were excluded. Computer navigation was used in the mechanical alignment group, and patient-specific cutting blocks were used in the kinematic alignment group. At 10 years, 86% (43) of the patients in the mechanical alignment group and 80% (39) in the kinematic alignment group were available for follow-up performed as a per-protocol analysis. The PROMs that we assessed included the Knee Society Score, Oxford Knee Score, WOMAC, Forgotten Joint Score, and EuroQol 5-Dimension score. Kaplan-Meier analysis was used to assess survivorship free from reoperation (any reason) and revision (change or addition of any component). A single blinded observer assessed radiographs for signs of aseptic loosening (as defined by the presence of progressive radiolucent lines in two or more zones), which was reported as survivorship free from loosening., Results: At 10 years, there was no difference in any PROM score measured between the groups. Ten-year survivorship free from revision (components removed or added) likewise did not differ between the groups (96% [95% CI 91% to 99%] for the mechanical alignment group and 91% [95% CI 83% to 99%] for the kinematic alignment group; p = 0.38). There were two revisions in the mechanical alignment group (periprosthetic fracture, deep infection) and four in the kinematic alignment group (two secondary patella resurfacings, two deep infections). There was no statistically significant difference in reoperations for any cause between the two groups. There was no difference with regard to survivorship free from loosening on radiographic review (χ 2 = 1.3; p = 0.52) (progressive radiolucent lines seen at 10 years were 0% for mechanical alignment and 3% for kinematic alignment)., Conclusion: Like the 2-year and 5-year outcomes previously reported, 10-year follow-up for this RCT demonstrated no functional or radiographic difference in outcomes between mechanical alignment and kinematic alignment TKA. Anticipated functional benefits of kinematic alignment were not demonstrated, and revision-free survivorship at 10 years did not differ between the two groups. Given the unknown long-term impact of kinematic alignment with regard to implant position (especially tibial component varus), we must conclude that mechanical alignment remains the reference standard for TKA. We could not demonstrate any advantage to kinematic alignment at 10-year follow-up., Level of Evidence: Level I, therapeutic study., Competing Interests: All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request., (Copyright © 2024 by the Association of Bone and Joint Surgeons.)

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., (Copyright © 2022 Elsevier Inc. All rights reserved.)

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., (© 2022. The Author(s).)

Religion and spirituality have long been considered important social determinants of human health, and there exists an extensive body of research to support such. End-of-life (EOL) may raise complex questions for individuals about religious and spiritual (R/S) values guiding advance care planning (ACP) and EOL care decisions, including the provision of spiritual care. This commentary will review the history and current national trends of ACP activities for EOL, principally within the United States. It will describe the relationship of religious variables and the attributes of selected research instruments used to study religious variables on ACP and EOL preferences. The review also summarizes unique ACP challenges for patients with neurocognitive disorders and severe mental illness. Findings disclose that higher levels of religiosity, reliance on religious coping, conservative faith traditions, and "belief in God's control over life's length and divine intervention have lower levels of ACP and more intensive EOL care preferences, although the provision of spiritual spiritual care at EOL mitigates intensive EOL care. Based upon the curated evidence, we propose an epistemological justification to consider "faith" as a separately defined religious variable in future ACP and EOL research. This review is relevant to geriatric psychiatrists and gerontological health care professionals, as they may be part of multidisciplinary palliative care teams; provide longitudinal care to patients with neurocognitive disorders and severe mental illness; and may provide diagnostic, emotional, and therapeutic services for patients and families who may struggle with EOL care decisions., (Copyright © 2021 American Association for Geriatric Psychiatry. Published by Elsevier Inc. All rights reserved.)

The great health paradox is that the least expensive and most effective public health measures available for addressing the COVID-19 pandemic-and other society-wide health challenges-have long been ignored and rejected in the United States in favor of more expensive and personalized care. The U.S. medical system is being overwhelmed in part because of this paradox. The authors argue that the country has invested excessively in acute care medical technology while investing insufficiently in its public health infrastructure. In this Invited Commentary, the authors recommend 5 steps that academic medicine should take to increase emphasis on and understanding of public health interventions to address society's health problems: (1) incorporate problem-based learning experiences in the medical school curriculum and community-based clinical rotations in public health departments, (2) better integrate schools of public health and schools of medicine, (3) encourage physicians to pursue public health careers, (4) educate the public about strategies for decreasing chronic illnesses, and (5) increase collaboration with colleagues around the world to identify and track outbreaks., (Copyright © 2022 by the Association of American Medical Colleges.)

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., (© 2021. Royal Academy of Medicine in Ireland.)

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., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

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., (Copyright © 2020 Royal College of Surgeons of Edinburgh (Scottish charity number SC005317) and Royal College of Surgeons in Ireland. Published by Elsevier Ltd. All rights reserved.)

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., (Copyright © 2021 Royal College of Surgeons of Edinburgh (Scottish charity number SC005317) and Royal College of Surgeons in Ireland. Published by Elsevier Ltd. All rights reserved.)

The coronavirus disease 2019 pandemic has meant that there is growing pressure on hospital resources, not least the availability of appropriate personal protective equipment (PPE), particularly face masks and respirator masks. Within the field of orthopaedic surgery, it is a common sight to see surgeons wearing 'space suits' (SSs) which comprise a helmet, hood and surgical gown. In this study, the authors made modifications to two different SS systems to incorporate a high-efficiency particulate air (HEPA) filter into the fan inlet to assess their potential as re-usable PPE systems for surgeons with regard to protection from a virus spread via respiratory droplets. The testing was carried out using particle counters upstream and downstream on a mannequin wearing two different SS systems with and without modifications to the fan inlet. The results show that using a layer of HEPA filter, cut to size and sealed to the fan inlet in the helmet, will reduce downstream particulates at the user's mouth by >99.5%; this is equivalent to a respirator mask. HEPA filter material is relatively cheap and can be used repeatedly, making this a viable alternative to disposable, and even resterilized, respirator masks in the setting of a respiratory-droplet-spread viral pandemic., (Copyright © 2020 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.)

Hearing loss is among the most frequent problems experienced by older adults, yet psychiatrists and other clinicians often ignore the problem as an aggravation rather than recognizing that the problem might benefit from appropriate hearing health care. Many psychiatric disorders have been associated with hearing loss, including depression, schizophrenia and other psychoses, anxiety, and neurocognitive disorders. In this article, hearing loss among older adults is reviewed, with special attention directed toward the recognition and proper referral to a hearing health care provider. Finally, major advances in hearing health care are discussed., (Copyright © 2019. Published by Elsevier Inc.)

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.

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., (Copyright © 2019 Royal College of Surgeons of Edinburgh (Scottish charity number SC005317) and Royal College of Surgeons in Ireland. Published by Elsevier Ltd. All rights reserved.)

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 R 50 and R 80-20 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 R 90 spacing) and for 13-16 MeV beams (1.0-cm R 90 spacing). Most machines failed these expectations, presumably due to tolerances for initial beam matching (0.05 cm in R 90 ; 0.10 cm in R 80-20 ) and ongoing quality assurance (0.2 cm in R 50 ). 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 R 50 and R 80-20 varied linearly and supralinearly with PME, respectively; however, both suggested a secondary dependence on FWHM. Hence, PME and FWHM could serve as surrogates for R 50 and R 80-20 for beam tuning by the accelerator engineer, possibly being more sensitive (e.g., 0.1 cm in R 80-20 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., (© 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.)

Hearing loss is among the most frequent problems experienced by older adults, yet psychiatrists and other clinicians often ignore the problem as an aggravation rather than recognizing that the problem might benefit from appropriate hearing health care. Many psychiatric disorders have been associated with hearing loss, including depression, schizophrenia and other psychoses, anxiety, and neurocognitive disorders. In this article, hearing loss among older adults is reviewed, with special attention directed toward the recognition and proper referral to a hearing health care provider. Finally, major advances in hearing health care are discussed., (Copyright © 2017 Elsevier Inc. All rights reserved.)

This retrospective analysis includes patients requiring Emergency Aeromedical Services (EAS) in 2014. The aim of this paper is to evaluate the HEMS service in a single centre and to accurately assess whether certain internationally validated criteria can predict admission rates better than the currently used criteria. Using the American College of Surgeons (ACS) trauma-related dispatch criteria, each case was retrospectively evaluated. Results showed the mean total criteria met were 2.73 (?=0.88) and 1.45 (?=0.82) in admitted and discharged patients respectively. The total criteria met had a significant predictive value on admission rates (p<0.05). Increased admission rates were shown in patients with a high Mechanism of Injury (MOI) (p<0.05). False positive rates of HEMS transfer were higher when applying the current criteria compared to the ACS criteria. ACS total criteria can predict admission in HEMS patients with a higher specificity than currently used guidelines.

Aim: This is a retrospective analysis of all consecutive patients requiring emergency aeromedical services (EAS) to a level II trauma centre. This analysis was performed to evaluate the new service to Tallaght Hospital in terms of: the criteria used for dispatch, an estimate of baseline efficiency of time critical management of patients, the cross-catchment transfer of patients., Methods: Data were provided by the EAS with respect to the patients brought to Tallaght Hospital not including inter-facility transfers for the calendar year 2013. Using this information patient records were matched to the electronic database. Once patients were identified, their hospital journey was catalogued using chart review. Using Google Maps and the EAS data an estimated road-time was calculated. Specific dispatch criteria were unavailable, however, using five broad categories outlined by the American College of Surgeons (ACS) for trauma related dispatch criteria each case was evaluated., Results: The EAS data had 52 cases which were reported to come to this unit. 48 patient records were accurately matched to this data. 25 % were discharged without speciality input. Seven patients died within 24 h only one of which was admitted under a speciality. 30 patients were admitted under specialist care with two requiring transfer to another centre. 80 % of admissions came under the primary management of the orthopaedic team. 11 patients required operative management, five required ICU management, three required chest drains and one patient required cardiac angiogram. Of the five dispatch criteria categories evaluated the mean number of criteria met was 3.1., Conclusion: 25 % of the patients were managed in the Emergency Department alone indicating an acceptable level of over-triage according to ACS guidelines. When comparing the dispatch criteria met for this 25 % there was no statistical difference compared with the other 75 %. Sensitivity and specificity analyses have looked at the question of dispatch criteria before and our data are comparable with international evidence. We suggest that further research be undertaken to develop this service to improve activation criteria and thereby the entire service delivered.

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., (Copyright © 2015 Royal College of Surgeons of Edinburgh (Scottish charity number SC005317) and Royal College of Surgeons in Ireland. Published by Elsevier Ltd. All rights reserved.)

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., (© 2016 The Authors.)

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.

Background: The implementation of the European work-time directive has created increased transitions of care during weekends as doctors adhere to a shift-work structure. This raises concerns over continuity of care and patient safety. To address this, doctors must develop a time efficient yet safe system of handover of patients to the team on-call. Intuitively weekend care provides the ideal setting to develop a handover tool., Aim: To develop and implement a process of surgical handover and to improve weekend discharge rate on a surgical service., Methods: Data was collected at three time-points over a 6 months period (October 2013-March 2014) encompassing development, implementation, re-evaluation and modification of the handover process. The outcomes measured were: number of inpatients, number of weekend discharges, length of stay (LOS) of inpatients recorded for the four weekends within the month, and total emergency response team (ERT) calls each month., Results: Mean number of included patients each month was 294 (σ = 14). Following the introduction of weekend handover there was a 40 % increase in weekend discharges which was consistent for subsequent time-points (p < 0.05). Following the second intervention there was a statistically significant reduction in mean LOS from 13 to 5.4 days (p < 0.05) and the total number of ERT calls for the month reduced from 12 to 4 (p < 0.05)., Conclusions: The standardisation of weekend handover using a combination of an electronic tool supplemented with verbal handover is feasible. It resulted in a significant improvement in surrogate markers of patient care quality.

Purpose: The purpose of this work was to adapt a lightweight, permanent magnet electron energy spectrometer for the measurement of energy spectra of therapeutic electron beams., Methods: An irradiation geometry and measurement technique were developed for an approximately 0.54-T, permanent dipole magnet spectrometer to produce suitable latent images on computed radiography (CR) phosphor strips. Dual-pinhole electron collimators created a 0.318-cm diameter, approximately parallel beam incident on the spectrometer and an appropriate dose rate at the image plane (CR strip location). X-ray background in the latent image, reduced by a 7.62-cm thick lead block between the pinhole collimators, was removed using a fitting technique. Theoretical energy-dependent detector response functions (DRFs) were used in an iterative technique to transform CR strip net mean dose profiles into energy spectra on central axis at the entrance to the spectrometer. These spectra were transformed to spectra at 95-cm source to collimator distance (SCD) by correcting for the energy dependence of electron scatter. The spectrometer was calibrated by comparing peak mean positions in the net mean dose profiles, initially to peak mean energies determined from the practical range of central-axis percent depth-dose (%DD) curves, and then to peak mean energies that accounted for how the collimation modified the energy spectra (recalibration). The utility of the spectrometer was demonstrated by measuring the energy spectra for the seven electron beams (7-20 MeV) of an Elekta Infinity radiotherapy accelerator., Results: Plots of DRF illustrated their dependence on energy and position in the imaging plane. Approximately 15 iterations solved for the energy spectra at the spectrometer entrance from the measured net mean dose profiles. Transforming those spectra into ones at 95-cm SCD increased the low energy tail of the spectra, while correspondingly decreasing the peaks and shifting them to slightly lower energies. Energy calibration plots of peak mean energy versus peak mean position of the net mean dose profiles for each of the seven electron beams followed the shape predicted by the Lorentz force law for a uniform z-component of the magnetic field, validating its being modeled as uniform (0.542 ± 0.027 T). Measured Elekta energy spectra and their peak mean energies correlated with the 0.5-cm (7-13 MeV) and the 1.0-cm (13-20 MeV) R90 spacings of the %DD curves. The full-width-half-maximum of the energy spectra decreased with decreasing peak mean energy with the exception of the 9-MeV beam, which was anomalously wide. Similarly, R80-20 decreased linearly with peak mean energy with the exception of the 9 MeV beam. Both were attributed to suboptimal tuning of the high power phase shifter for the recycled radiofrequency power reentering the traveling wave accelerator., Conclusions: The apparatus and analysis techniques of the authors demonstrated that an inexpensive, lightweight, permanent magnet electron energy spectrometer can be used for measuring the electron energy distributions of therapeutic electron beams (6-20 MeV). The primary goal of future work is to develop a real-time spectrometer by incorporating a real-time imager, which has potential applications such as beam matching, ongoing beam tune maintenance, and measuring spectra for input into Monte Carlo beam calculations.

Purpose: Wear of ceramic orthopedic devices generates nanoparticles in vivo that may present a different biological character from the monolithic ceramic from which they are formed. The current work investigated protein adsorption from human plasma on alumina nanoparticles and monolithic samples representative of both wear particles and the ceramic components as implanted., Materials and Methods: A physicochemical characterization of the particles and their dispersion state was carried out, and the protein adsorption profiles were analyzed using 1D SDS-PAGE and mass spectrometry., Results: Significant differences in protein-binding profiles were identified where the nanoparticles selectively bound known transporter proteins rather than the more highly abundant serum proteins that were observed on the monoliths., Conclusions: Proteins associated with opsonization of particles were seen to be present in the protein corona of the nanoparticles, which raises questions regarding the role of wear particles in periprosthetic tissue inflammation and aseptic loosening.

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 &lt; 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 &lt; 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.

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.

A protocol is presented for the calculation of monitor units (MU) for photon and electron beams, delivered with and without beam modifiers, for constant source-surface distance (SSD) and source-axis distance (SAD) setups. This protocol was written by Task Group 71 of the Therapy Physics Committee of the American Association of Physicists in Medicine (AAPM) and has been formally approved by the AAPM for clinical use. The protocol defines the nomenclature for the dosimetric quantities used in these calculations, along with instructions for their determination and measurement. Calculations are made using the dose per MU under normalization conditions, D'0, that is determined for each user's photon and electron beams. For electron beams, the depth of normalization is taken to be the depth of maximum dose along the central axis for the same field incident on a water phantom at the same SSD, where D'0 = 1 cGy/MU. For photon beams, this task group recommends that a normalization depth of 10 cm be selected, where an energy-dependent D'0 ≤ 1 cGy/MU is required. This recommendation differs from the more common approach of a normalization depth of dm, with D'0 = 1 cGy/MU, although both systems are acceptable within the current protocol. For photon beams, the formalism includes the use of blocked fields, physical or dynamic wedges, and (static) multileaf collimation. No formalism is provided for intensity modulated radiation therapy calculations, although some general considerations and a review of current calculation techniques are included. For electron beams, the formalism provides for calculations at the standard and extended SSDs using either an effective SSD or an air-gap correction factor. Example tables and problems are included to illustrate the basic concepts within the presented formalism.

Purpose: To examine the feasibility of volumetric modulated arc therapy (VMAT) for post mastectomy radiotherapy (PMRT)., Methods and Materials: Fifteen PMRT patients previously treated at our clinic with helical tomotherapy (HT) were identified for the study. Planning target volumes (PTV) included the chest wall and regional lymph nodes. A systematic approach to constructing VMAT that met the clinical goals was devised. VMAT plans were then constructed for each patient and compared with HT plans with which they had been treated. The resulting plans were compared on the basis of PTV coverage; dose homogeneity index (DHI) and conformity index (CI); dose to organs at risk (OAR); tumor control probability (TCP), normal tissue complication probability (NTCP) and secondary cancer complication probability (SCCP); and treatment delivery time. Differences were tested for significance using the paired Student's t-test., Results: Both modalities produced clinically acceptable PMRT plans. VMAT plans showed better CI (p<0.01) and better OAR sparing at low doses than HT plans, particularly at doses less than 5 Gy. On the other hand, HT plans showed better DHI (p<0.01) and showed better OAR sparing at higher doses. Both modalities achieved nearly 100% tumor control probability and approximately 1% NTCP in the lungs and heart. VMAT showed lower SCCP than HT (p<0.01), though both plans showed higher SCCP values than conventional mixed beam (electron-photon) plans reported by our group previously. VMAT plans required 66.2% less time to deliver than HT., Conclusions: Both VMAT and HT provide acceptable treatment plans for PMRT. Both techniques are currently utilized at our institution.

Purpose: To assess the accuracy and precision of cone-beam computed tomography (CBCT)-guided intensity modulated radiation therapy (IMRT)., Methods and Materials: A 7-field intensity modulated radiation therapy plan was constructed for an anthropomorphic head phantom loaded with a custom cassette containing radiochromic film. The phantom was positioned on the treatment table at 9 locations: 1 "correct" position and 8 "misaligned" positions along 3 orthogonal axes. A commercial kilovoltage cone-beam computed tomography (kV-CBCT) system (VolumeView, Elekta AB, Stockholm, Sweden) was then used to align the phantom prior to plan delivery. The treatment plan was delivered using the radiation therapy delivery system (Infinity; Elekta AB) 3 times for each of the 9 positions, allowing film measurement of the delivered dose distribution in 3 orthogonal planes. Comparison of the planned and delivered dose profiles along the major axes provided an estimate of the accuracy and precision of CBCT-guided IMRT., Results: On average, targeting accuracy was found to be within 1 mm in all 3 major anatomic planes. Over all 54 measured dose profiles, the means and standard errors of the displacement of the center of the field between the measured and calculated profiles for each of the right-left, anterior-posterior, and superior-inferior axes were +0.08 ± 0.07 mm, +0.60 ± 0.08 mm, and +0.78 ± 0.16 mm, respectively. Agreement between planned and measured 80% profiles was less than 0.4 mm on either side along the right-left axis. A systematic shift of the measured profile of slightly less than 1 mm in anterior and superior directions was noted along the anterior-posterior and superior-inferior axes, respectively., Conclusions: Submillimeter targeting accuracy can be achieved using a commercial kV-CBCT IGRT system., (Copyright © 2014 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)

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.

Background and Purpose: To investigate combining unmodulated electron beams with intensity-modulated radiation therapy to improve dose distributions for superficial head and neck cancers, and to compare mixed beam plans with helical tomotherapy., Materials and Methods: Mixed beam and helical tomotherapy dose plans were developed for two patients with parotid gland tumors and two patients with nasal cavity tumors. Mixed beam plans consisted of various weightings of a enface electron beam and IMRT, which was optimized after calculation of the electron dose to compensate for heterogeneity in the electron dose distribution within the target volume., Results: Helical tomotherapy plans showed dose conformity and homogeneity in the target volume that was equal to or better than the mixed beam plans. Electron-only plans tended to show the lowest doses to normal tissues, but with markedly worse dose conformity and homogeneity than in the other plans. However, adding a 20% IMRT dose fraction (i.e., IMRT:electron weighting = 1:4) to the electron plan restored target conformity and homogeneity to values comparable to helical tomotherapy plans, while maintaining lower normal tissue dose., Conclusions: Mixed beam treatments offer some dosimetric advantages over IMRT or helical tomotherapy for target depths that do not exceed the useful range of the electron beam. Adding a small IMRT component (e.g., IMRT:electron weighting = 1:4) to electron beam plans markedly improved target dose homogeneity and conformity for the cases examined in this study.

Helical tomotherapy plans using a combination of pitch and jaw width settings were developed for 3 patients previously treated for head and neck cancer. Three jaw widths (5, 2.5, and 1 cm) and 4 pitches (0.86, 0.43, 0.287, and 0.215) were used with a (maximum) modulation factor setting of 4. Twelve plans were generated for each patient using an identical optimization procedure (e.g., number of iterations, objective weights, and penalties, etc.), based on recommendations from TomoTherapy (Madison, WI). The plans were compared using isodose plots, dose volume histograms, dose homogeneity indexes, conformity indexes, radiobiological models, and treatment times. Smaller pitches and jaw widths showed better target dose homogeneity and sparing of normal tissue, as expected. However, the treatment time increased inversely proportional to the jaw width, resulting in delivery times of 24 ± 1.9 min for the 1-cm jaw width. Although treatment plans produced with the 2.5-cm jaw were dosimetrically superior to plans produced with the 5-cm jaw, subsequent calculations of tumor control probabilities and normal tissue complication probabilities suggest that these differences may not be radiobiologically meaningful. Because treatment plans produced with the 5-cm jaw can be delivered in approximately half the time of plans produced with the 2.5-cm jaw (5.1 ± 0.6 min vs. 9.5 ± 1.1 min), use of the 5-cm jaw in routine treatment planning may be a viable approach to decreasing treatment delivery times from helical tomotherapy units., (Copyright © 2011 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.)

Purpose: To investigate the potential of helical tomotherapy for postmastectomy radiation therapy., Methods and Materials: By use of the TomoTherapy Hi-Art II treatment-planning system (TomoTherapy Inc., Madison, WI), helical tomotherapy dose plans were developed for 5 patients and compared with the mixed-beam (electron-photon) plans with which they had been treated. The TomoTherapy plans were evaluated by use of dose-volume quantities, tumor control probability, normal tissue complication probability (NTCP), and secondary cancer complication probability (SCCP)., Results: The TomoTherapy plans showed better dose homogeneity in the planning treatment volume containing the chest wall and internal mammary nodes (p = 0.001) and eliminated the need for abutting fields. For the normal tissues, the TomoTherapy plans showed a smaller fractional volume receiving 20 Gy or greater for the ipsilateral lung (p = 0.05), no change in NTCP for postradiation pneumonitis, increased SCCP for each lung and both lungs together (p < 0.02), no change in the volume of the heart receiving more than 15 Gy, no change in NTCP for excess cardiac mortality, and a larger mean dose and SCCP in the contralateral breast (p < 0.001). For nonspecific tissues, the volume receiving between 5 Gy and 25 Gy and SCCP were both larger for the TomoTherapy plans (p < 0.01). Total SCCP was larger for the TomoTherapy plans (p = 0.001)., Conclusions: Overall, the TomoTherapy plans had comparable tumor control probability and NTCP to the mixed-beam plans and increased SCCP. The TomoTherapy plans showed significantly greater dose homogeneity in the chest wall, which offers the potential for improved cosmesis after treatment. These factors have resulted in TomoTherapy often being the treatment of choice for postmastectomy radiation therapy in our clinic., ((c) 2010 Elsevier Inc. All rights reserved.)

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.

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.

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.

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.

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.

Asymmetric collimators or heavily blocked fields with physical wedges are still encountered in daily practice. In such cases, a reliable dosimetry system is necessary to perform manual dose and monitor unit calculations in order to independently verify the calculations of commercial treatment planning systems. In this work, primary wedged off-axis ratios (POAR(w)s) that account for changes in the beam intensity along both the wedge gradient and perpendicular directions of the photon field, when asymmetric collimators are applied, were measured experimentally at specific depths. The measurements were made in phantom with an ion chamber along the wedge gradient and the perpendicular directions under 'good geometry' conditions. A consistent formalism was presented that could easily be implemented in the clinical environment as an independent verification of the calculations by a treatment planning system. The accuracy of the method was found to be dependent on the specific wedge used, off-axis distance and depth in the phantom. In our study, the accuracy was within 2% in most cases for both energies. We concluded that the primary wedged off-axis ratios when used along with open symmetric field dosimetric parameters could provide adequate accuracy for manual monitor unit calculations.

We present results of investigations of the clinical significance of variations in the value of the 4-mm-collimator output factor, OF(4/18). Changes in treatment volume, dose-volume histograms (DVHs), and isodose distributions were studied, by varying OF(4/18) up to 20%. The variations were performed on a sample of clinical patient treatment plans for which the 4 mm collimator was used. Although smaller effects are noted for the prescription isodose line, greater dosimetric changes occur for higher dose regions within the target., ((c) 2003 American College of Medical Physics.)

A-60-year-old man with medically intractable left-sided maxillary division trigeminal neuralgia had severe cardiac disease, was dependent on an internal defibrillator and could not undergo magnetic resonance imaging. The patient was successfully treated using computerized tomography (CT) cisternography and gamma knife radiosurgery. The patient was pain free 2 months after GKS. Contrast cisternography with CT scanning is an excellent alternative imaging modality for the treatment of patients with intractable trigeminal neuralgia who are unable to undergo MR imaging.

A method is introduced to calculate wedge factors for an enhanced dynamic wedge (EDW). An analytic formula has been derived that allows the determination of wedge factors at the center of symmetric and asymmetric photon fields. The formalism is an extension of the "MU fraction approximation," which holds that the dynamic wedge factor is equal to the fraction of MU delivered to the point of calculation. Extensive data are presented, comparing measured enhanced dynamic wedge factors with the current method and the MU fraction model for both symmetric and asymmetric fields. For both 6 and 18 MV photons, the current method demonstrates improved results: Agreement to within 1% is obtained in all symmetric fields and within 2% for all asymmetric fields compared with discrepancies of up to 4% obtained with the MU fraction model.