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Production of radioisotopes in medical linear accelerators (linacs) is of concern when the beam energy exceeds the threshold for the photonuclear interaction. Staff and patients may receive a radiation dose as a result of the induced radioactivity in the linac. Gamma-ray spectroscopy was used to identify the isotopes produced following the delivery of 18MV photon beams from a Varian 21EX and an Elekta Synergy. The prominent radioisotopes produced include 187W, 63Zn, 56Mn, 24Na and 28Al in both linac models. The dose rate was measured at the beam exit window (12.6 μSv in the first 10 min) following 18 MV total body irradiation (TBI) beams. For a throughput of 24 TBI patients per year, staff members are estimated to receive an annual dose of up to 750 μSv at the patient location. This can be further reduced to 65 μSv by closing the jaws before re-entering the treatment bunker. [ABSTRACT FROM AUTHOR]

The outlook for national health spending calls for continued steady growth. Spending growth is projected to be 6.7 percent in 2007, similar to its rate in 2006. Average annual growth over the projection period is expected to be 6.7 percent. Slower growth in private spending toward the end of the period is expected to be offset by stronger growth in public spending. The health share of gross domestic product (GDP) is expected to increase to 16.3 percent in 2007 and then rise throughout the projection period, reaching 19.5 percent of GDP by 2017. [ABSTRACT FROM AUTHOR]

During the projection period (2008DS2018), average annual growth in national health spending is projected to be 6.2 percentDL2.1 percentage points faster than average annual growth in gross domestic product (GDP). The health share of GDP is anticipated to rise rapidly from 16.2 percent in 2007 to 17.6 percent in 2009, largely as a result of the recession, and then climb to 20.3 percent by 2018. Public payers are expected to become the largest source of funding for health care in 2016 and are projected to pay for more than half of all national health spending in 2018. [ABSTRACT FROM AUTHOR]

Growth in national health spending is projected to slow slightly from 6.9 percent in 2005 to 6.8 percent in 2006, marking the fourth consecutive year of a slowing trend. The health share of gross domestic product (GDP) is expected to hold steady in 2006 before resuming its historical upward trend, reaching 19.6 percent of GDP by 2016. Prescription drug spending growth is expected to accelerate to 6.5 percent in 2006. Medicare prescription drug coverage has dramatically changed the distribution of drug spending among payers, but the net effect on aggregate spending is anticipated to be small. [ABSTRACT FROM AUTHOR]

Background and Purpose: Synthetic diamond detectors offer real time measurement of dose in radiotherapy applications which require high spatial resolution. Additional considerations and corrections are required for measurements where the diamond detector is orientated at various angles to the incident beam. This study investigated diamond detectors for end-to-end testing of Stereotactic Body Radiotherapy (SBRT) and Stereotactic Radiosurgery (SRS) in the context of dosimetry audits., Material and Methods: Seven individual diamond detectors were investigated and compared with respect to warm up stability, dose-rate dependence, linearity, detector shadowing, energy response, cross-calibration, angular dependence and positional sensitivity in SBRT and SRS., Results: Large variation in the cross calibration factors was found between the seven individual detectors. For each detector, the energy dependence in the cross calibration factor was on average <0.6% across the beam qualities investigated (Co-60 Gamma Knife, and MV beams with TPR 20,10 0.684-0.733). The angular corrections for individual fields were up to 5%, and varied with field size. However, the average angular dependence for all fields in a typical SRS treatment delivery was <1%. The overall measurement uncertainty was 3.6% and 3.1% (2σ) for an SRS and SBRT treatment plan respectively., Conclusion: Synthetic diamond detectors were found to be reliable and robust for end-to-end dosimetry in SBRT and SRS applications. Orientation of the detector relative to the beam axis is an important consideration, as significant corrections are required for angular dependence., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Crown Copyright © 2021 Published by Elsevier B.V. on behalf of European Society of Radiotherapy & Oncology.)

Purpose: The aim of this study is to investigate overdose to organs at risk (OARs) observed in dosimetry audits in Monte Carlo (MC) algorithms and Linear Boltzmann Transport Equation (LBTE) algorithms. The impact of penumbra modeling on OAR dose was assessed with the adjustment of MC modeling parameters and the clinical relevance of the audit cases was explored with a planning study of spine and head and neck (H&N) patient cases., Methods: Dosimetric audits performed by the Australian Clinical Dosimetry Service (ACDS) of 43 anthropomorphic spine plans and 1318 C-shaped target plans compared the planned dose to doses measured with ion chamber, microdiamond, film, and ion chamber array. An MC EGSnrc model was created to simulate the C-shape target case. The electron cut-off energy E cut(kinetic) was set at 500, 200, and 10 keV, and differences between 1 and 3 mm voxel were calculated. A planning study with 10 patient stereotactic body radiotherapy (SBRT) spine plans and 10 patient H&N plans was calculated in both Acuros XB (AXB) v15.6.06 and Anisotropic Analytical Algorithm (AAA) v15.6.06. The patient contour was overridden to water as only the penumbral differences between the two different algorithms were under investigation., Results: The dosimetry audit results show that for the SBRT spine case, plans calculated in AXB are colder than what is measured in the spinal cord by 5%-10%. This was also observed for other audit cases where a C-shape target is wrapped around an OAR where the plans were colder by 3%-10%. Plans calculated with Monaco MC were colder than measurements by approximately 7% with the OAR surround by a C-shape target, but these differences were not noted in the SBRT spine case. Results from the clinical patient plans showed that the AXB was on average 7.4% colder than AAA when comparing the minimum dose in the spinal cord OAR. This average difference between AXB and AAA reduced to 4.5% when using the more clinically relevant metric of maximum dose in the spinal cord. For the H&N plans, AXB was cooler on average than AAA in the spinal cord OAR (1.1%), left parotid (1.7%), and right parotid (2.3%). The EGSnrc investigation also noted similar, but smaller differences. The beam penumbra modeled by E cut(kinetic)  = 500 keV was steeper than the beam penumbra modeled by E cut(kinetic)  = 10 keV as the full scatter is not accounted for, which resulted in less dose being calculated in a central OAR region where the penumbra contributes much of the dose. The dose difference when using 2.5 mm voxels of the center of the OAR between 500 and 10 keV was 3%, reducing to 1% between 200 and 10 keV., Conclusions: Lack of full penumbral modeling due to approximations in the algorithms in MC based or LBTE algorithms are a contributing factor as to why these algorithms under-predict the dose to OAR when the treatment volume is wrapped around the OAR. The penumbra modeling approximations also contribute to AXB plans predicting colder doses than AAA in areas that are in the vicinity of beam penumbra. This effect is magnified in regions where there are many beam penumbras, for example in the spinal cord for spine SBRT cases., (© 2021 Commonwealth of Australia. Medical Physics © 2021 American Association of Physicists in Medicine.)

This qualitative research study examined the educational provision for children with medical needs in Irish hospital schools using a case study approach encompassing the perspectives and experiences of 12 teachers currently teaching in two paediatric hospital schools. Document analysis and semi-structured interviews were employed across two research sites, which included a review of each school's whole-school evaluation, enrolment policy, school improvement plan, database, and school website, to compile information to inform each case study. Scrutiny of the documentation also assisted in the formation of the interview questions used in the semi-structured interviews. Thematic analysis was conducted on the data collated, and four key themes were identified. The findings revealed that participating hospital teachers employ a variety of individual and collaborative practices to prepare for and deliver education to hospitalised students. The research illuminated the routine of planning for a child's education, comprising a process of information gathering and recording, multi-disciplinary collaboration, and engagement strategies. Hospital teachers reported the emotional aspect of their role as the biggest challenge they experience, while time constraints, teaching across a variety of class levels and needs, and a lack of recognition of the parameters within they must operate were further challenges identified., Competing Interests: The researcher has worked with many of the participants involved in the study through their career as hospital school teachers and considered it a duty to remain acutely aware of the potential for bias and prejudice. Ensuring confidentiality was maintained at all times, interviews were conducted in confidence and were not discussed with any other staff members. Interview questions were carefully scripted in order to avoid any leading of participants’ responses. The questions as designed were not deviated from, and the interview schedule was identically executed for each, ensuring all participants were asked the same questions., (Copyright: © 2021 The Author(s).)

Purpose: The purpose of the study was to establish, using a retrospective analysis of existing hospital records, the long-term stability and accuracy of a high-dose-rate brachytherapy well chamber. This should be assessed to determine reliability and appropriate calibration frequency. The accrual of long-term data that demonstrates the stability of our chamber may inform others of the performance they might expect from similar equipment., Methods and Materials: We evaluated air kerma strength measurements made with the PTW 32002 (Nucletron 077.091) high-dose-rate well chamber on 72 192 Ir sources over an 18-year period and the seven calibrations of that chamber which span a 27-year period., Results: Consecutive air kerma strength measurements agreed within 0.01% on average. The chamber measurement agreed with the source specification within 0.02% on average, but was up to 1.4% during some calibration periods. The chamber calibration coefficient varied by a maximum of 5% over seven chamber calibration measurements., Conclusions: The constancy of the well chamber current compared with the source manufacturer suggests that our chamber has been stable to better than 2% over a period of 18 years. Although the chamber has received different calibration coefficients over time, these coefficients are within the combined uncertainties of any two calibrations and are consistent with the chamber being stable. The agreement we have observed between clinical measurements and the source manufacturer would justify an action level for further investigation of 1%, for this specific chamber., (Copyright © 2021 American Brachytherapy Society. All rights reserved.)

Purpose: Consistency between different international quality assurance groups is important in the progress toward similar standards and expectations in radiotherapy dosimetry around the world, and in the context of consistent clinical trial data from international trial participants. This study compares the dosimetry audit methodology and results of two international quality assurance groups performing a side-by-side comparison at the same radiotherapy department, and interrogates the ability of the audits to detect deliberately introduced errors., Methods: A comparison of the core dosimetry components of reference and non-reference audits was conducted by the Imaging and Radiation Oncology Core (IROC, Houston, USA) and the Australian Clinical Dosimetry Service (ACDS, Melbourne, Australia). A set of measurements were conducted over 2 days at an Australian radiation therapy facility in Melbourne. Each group evaluated the reference dosimetry, output factors, small field output factors, percentage depth dose (PDD), wedge, and off-axis factors according to their standard protocols. IROC additionally investigated the Electron PDD and the ACDS investigated the effect of heterogeneities. In order to evaluate and compare the performance of these audits under suboptimal conditions, artificial errors in percentage depth dose (PDD), EDW, and small field output factors were introduced into the 6 MV beam model to simulate potential commissioning/modeling errors and both audits were tested for their sensitivity in detecting these errors., Results: With the plans from the clinical beam model, almost all results were within tolerance and at an optimal pass level. Good consistency was found between the two audits as almost all findings were consistent between them. Only two results were different between the results of IROC and the ACDS. The measurements of reference FFF photons showed a discrepancy of 0.7% between ACDS and IROC due to the inclusion of a 0.5% nonuniformity correction by the ACDS. The second difference between IROC and the ACDS was seen with the lung phantom. The asymmetric field behind lung measured by the ACDS was slightly (0.3%) above the ACDS's pass (optimal) level of 3.3%. IROC did not detect this issue because their measurements were all assessed in a homogeneous phantom. When errors were deliberately introduced neither audit was sensitive enough to pick up a 2% change to the small field output factors. The introduced PDD change was flagged by both audits. Similarly, the introduced error of using 25° wedge instead of 30° wedge was detectible in both audits as out of tolerance., Conclusions: Despite different equipment, approach, and scope of measurements in on-site audits, there were clear similarities between the results from the two groups. This finding is encouraging in the context of a global harmonized approach to radiotherapy quality assurance and dosimetry audit., (© 2019 The Authors. Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.)

Background and Purpose: Independent dosimetry audits improve quality and safety of radiation therapy. This work reports on design and findings of a comprehensive 3D conformal radiotherapy (3D-CRT) Level III audit., Materials and Methods: The audit was conducted as onsite audit using an anthropomorphic thorax phantom in an end-to-end test by the Australian Clinical Dosimetry Service (ACDS). Absolute dose point measurements were performed with Farmer-type ionization chambers. The audited treatment plans included open and half blocked fields, wedges and lung inhomogeneities. Audit results were determined as Pass Optimal Level (deviations within 3.3%), Pass Action Level (greater than 3.3% but within 5%) and Out of Tolerance (beyond 5%), as well as Reported Not Scored (RNS). The audit has been performed between July 2012 and January 2018 on 94 occasions, covering approximately 90% of all Australian facilities., Results: The audit pass rate was 87% (53% optimal). Fifty recommendations were given, mainly related to planning system commissioning. Dose overestimation behind low density inhomogeneities by the analytical anisotropic algorithm (AAA) was identified across facilities and found to extend to beam setups which resemble a typical breast cancer treatment beam placement. RNS measurements inside lung showed a variation in the opposite direction: AAA under-dosed a target beyond lung and over-dosed the lung upstream and downstream of the target. Results also highlighted shortcomings of some superposition and convolution algorithms in modelling large angle wedges., Conclusions: This audit showed that 3D-CRT dosimetry audits remain relevant and can identify fundamental global and local problems that also affect advanced treatments., (Crown Copyright © 2018 Published by Elsevier B.V. on behalf of European Society of Radiotherapy & Oncology.)

High energy radiotherapy can produce contaminant neutrons through the photonuclear effect. Patients receiving external beam radiation therapy to the pelvis may have high-density hip prostheses. Metallic materials such as those in hip prostheses, often have high cross-sections for neutron interaction. In this study, Thackray (UK) prosthetic hips have been irradiated by 18 MV radiotherapy beams to evaluate the additional dose to patients from the activation products. Hips were irradiated in- and out-of field at various distances from the beam isocenter to assess activation caused in-field by photo-activation, and neutron activation which occurs both in and out-of-field. NaI(Tl) scintillator detectors were used to measure the subsequent gamma-ray emissions and their half-lives. High sensitivity Mg, Cu, P doped LiF thermoluminescence dosimeter chips (TLD-100H) were used to measure the subsequent dose at the surface of a prosthesis over the 12 h following an in-field irradiation of 10,000 MU to a hip prosthesis located at the beam isocenter in a water phantom. 53 Fe, 56 Mn, and 52 V were identified within the hip following irradiation by radiotherapy beams. The dose measured at the surface of a prosthesis following irradiation in a water phantom was 0.20 mGy over 12 h. The dose at the surface of prostheses irradiated to 200 MU was below the limit of detection (0.05 mGy) of the TLD100H. Prosthetic hips are activated by incident photons and neutrons in high energy radiotherapy, however, the dose resulting from activation is very small., (© 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.)

Intrafraction organ deformation may be accounted for by inclusion of temporal information in dose calculation models. In this article, we demonstrate a quasi-4-dimensional method for improved risk estimation. Conventional 3-dimensional and quasi-4-dimensional calculations employing dose warping for dose accumulation were undertaken for patients with liver metastases planned for 42 Gy in 6 fractions of stereotactic body radiotherapy. Normal tissue complication probabilities and stochastic risks for radiation-induced carcinogenesis and cardiac complications were evaluated for healthy peripheral structures. Hypothetical assessments of other commonly employed dose/fractionation schedules on normal tissue complication probability estimates were explored. Conventional 3-dimensional dose computation may result in significant under- or overestimation of doses to organ at risk. For instance, doses differ (on average) by 17% (σ = 14%) for the left kidney, by 14% (σ = 7%) for the right kidney, by 7% (σ = 9%) for the large bowel, and by 10% (σ = 14%) for the duodenum. Discrepancies in the excess relative risk range up to about 30%. The 3-dimensional approach was shown to result in cardiac complication risks underestimated by >20%. For liver stereotactic body radiotherapy, we have shown that conventional 3-dimensional dose calculation may significantly over-/underestimate dose to organ at risk (90%-120% of the 4-dimensional estimate for the mean dose and 20%-150% for D2%). Providing dose estimates that most closely represent the actual dose delivered will provide valuable information to improve our understanding of the dose response for partial volume irradiation using hypofractionated schedules. Excess relative risks of radiocarcinogenesis were shown to range up to approximately excess relative risk = 4 and the prediction thereof depends greatly on the use of either 3-dimensional or 4-dimensional methods (with corresponding results differing by tens of percent)., (© The Author(s) 2015.)

The economic recession and rising unemployment-plus changing demographics and baby boomers aging into Medicare-are among the factors expected to influence health spending during 2009-2019. In 2009 the health share of gross domestic product (GDP) is expected to have increased 1.1 percentage points to 17.3 percent-the largest single-year increase since 1960. Average public spending growth rates for hospital, physician and clinical services, and prescription drugs are expected to exceed private spending growth in the first four years of the projections. As a result, public spending is projected to account for more than half of all U.S. health care spending by 2012.

Growth in national health spending is projected to slow in 2005 to 7.4 percent, from a peak of 9.1 percent in 2002. Private health insurance premiums are projected to slow to 6.6 percent in 2005, with a rebound expected in 2007. The introduction of Medicare Part D drug coverage in 2006 produces a dramatic shift in spending across payers but has little net effect on aggregate spending growth. Health spending is expected to consistently outpace gross domestic product (GDP) over the coming decade, accounting for 20 percent of GDP by 2015.

National health spending growth is anticipated to remain stable at just over 7.0 percent through 2006, the result of diverging public- and private-sector spending trends. The faster public-sector spending growth is exemplified by the introduction of the new Medicare drug benefit in 2006. While this benefit is anticipated to have only a minor impact on overall health spending, it will result in a significant shift in funding from private payers and Medicaid to Medicare. By 2014, total health spending is projected to constitute 18.7 percent of gross domestic product, from 15.3 percent in 2003.

The rate of growth in national health expenditures is projected to fall to 7.8 percent in 2003 because of slower private and public spending growth. However, during the next ten years health spending growth is expected to outpace economic growth. As a result, the health share of gross domestic product (GDP) is projected to increase from 14.9 percent in 2002 to 18.4 percent in 2013. The recently passed Medicare drug benefit legislation (not included in these projections) is not anticipated to have a large impact on overall national health spending, but it can be expected to cause sizable shifts in payment sources.

We forecast a slowdown in national health spending growth in 2002 and 2003, reflecting slower projected Medicare and private personal health spending growth. These factors outweigh higher projected Medicaid spending growth, caused by weak labor markets, and an expectation of continued high private health insurance premium inflation related to the underwriting cycle. Over the entire projection period, national health spending growth is still expected to outpace economic growth. The result is that the health share of gross domestic product is projected to increase from 14.1 percent in 2001 to 17.7 percent in 2012.

This paper describes the most recent ten-year projections of national health spending. projections, produced annually, are based on econometric and actuarial models of the health sector. Our current outlook includes a sharper near-term increase in the health sector's share of gross domestic product (GDP), which reaches 16.8 percent by 2010, compared with the 15.9 percent projected last year. This difference largely reflects legislation-driven increases in public spending growth combined with a weaker economic outlook. Recent acceleration in private-sector health spending is projected to peak in 2002.