Technological Advances In Radiotherapy Research Articles

SU-F-T-351: Establishing a Workflow for IMRT Pre-Treatment Reviews for NRG-GY006 Clinical Trial

Purpose: To establish a workflow for NRG-GY006 IMRT pre-treatment reviews, incorporating advanced radiotherapy technologies being evaluated as part of the clinical trial. Methods: Pre-Treatment reviews are required for every IMRT case as part of NRG-GY006 (a randomized phase II trial of radiation therapy and cisplatin alone or in combination with intravenous triapine in women with newly diagnosed bulky stage I B2, stage II, IIIB, or IVA cancer of the uterine cervix or stage II-IVA vaginal cancer. The pretreatment review process includes structures review and generating an active bone marrow(ABM)- to be used as an avoidance structure during IMRT optimization- and evaluating initial IMRT plan quality using knowledgeengineering based planning (KBP). Institutions will initially submit their simulation CT scan, structures file and PET/CT to IROC QA center for generating ABM. The ABM will be returned to the institution for use in planning. Institutions will then submit an initial IMRT plan for review and will receive information back following implementation of a KBP algorithm, for use in re-optimization, before submitting the final IMRT used for treatment. Results: ABM structure is generated using MIM vista software (Version 6.5, MIM corporation, Inc.). Here, the planning CT and the diagnostic PET/CT are fused and a sub threshold structure is auto segmented above the mean value of the SUV of the bone marrow. The generated ABM were compared with those generated with other software system (e.g. Velocity, Varian) and Dice coefficient (reflects the overlap of structures) ranged between 80 – 90% was achieved. A KBP model was built in Varian Eclipse TPS using the RapidPlan KBP software to perform plan quality assurance. Conclusion: The workflow for IMRT pretreatment reviews has been established. It represents a major improvement of NRG Oncology clinical trial quality assurance and incorporates the latest radiotherapy technologies as part of NCI clinical trials. This project was supported by grants U24CA180803 (IROC), UG1CA189867 (NCORP), U10CA180868 (NRG Oncology Operations), U10CA180822 (NRG Oncology SDMC) from the National Cancer Institute (NCI) and PA CURE grant

34 - Short-lived Positron Emitters in Beam-on PET Imaging During Proton Therapy

Positron emission tomography is so far the only method for in-vivo dose delivery verification in hadron therapy that is in clinical use. PET imaging during irradiation maximizes the number of detected counts and minimizes washout. In such a scenario, also short-lived positron emitters will be observed. As very little is known on the production of these nuclides, we determined which ones are relevant for proton therapy treatment verification. In order to be relevant, nuclides have to be produced close to the distal edge and thus at rather low proton energy. Therefore we measured the integral production of short-lived positron emitters in the stopping of 55 MeV protons in carbon, oxygen, phosphorus and calcium. The experiments were performed at the irradiation facility of the AGOR cyclotron at KVI-Center for Advanced Radiation Technology, University of Groningen. The positron emitters were identified based on their half-life. In order to do this, the proton beam was pulsed, i.e. delivered as a succession of beam-on and beam-off periods, and the time evolution of the 511 keV positron annihilation photons was recorded. A half-life analysis of the beam-off period allowed to determine the production rates of separate nuclides. The 511 keV photons were detected by a germanium clover detector [1]. A correction for the escape of positrons from the target, determined via Monte Carlo simulations, was applied. In the stopping of 55 MeV protons, the most copiously produced short-lived nuclides and their production rates relative to the relevant long-lived nuclides are: 12N (T1/2 = 11 ms) on carbon (9% of the 11C production), 29P (T1/2 = 4.1 s) on phosphorus (20% of the 30P production) and 38mK (T1/2 = 0.92 s) on calcium (113% of the 38gK production). No short-lived nuclides are produced on water (i.e. oxygen). The experimental production rates are used to calculate the production on PMMA and a representative set of 4 tissue materials. [fig. 1] The number of decays per 55 MeV proton stopped in these materials, integrated over an irradiation, is calculated as function of the duration of the irradiation. The most noticeable result is that for an irradiation in (carbon-rich) adipose tissue, 12N will dominate the PET image up to an irradiation duration of 70 s. On bone tissue, 15O dominates over 12N after 8-15 s (depending on the carbon-to-oxygen ratio). Considering nuclides created on phosphorus and calcium, the short-lived ones provide 2.5 times more decays than the long-lived ones during a 70 s irradiation. Bone tissue will thus be better visible in beam-on PET compared to PET imaging after an irradiation. The results warrant detailed investigations into the energy-dependent production of 12N, 29P and 38mK and their effect on PET imaging during proton irradiations.

Squamous-cell carcinoma of the anus: progress in radiotherapy treatment.

Chemoradiotherapy is the standard-of-care treatment of squamous-cell carcinoma of the anus (SCCA), and this has not changed in decades. Radiation doses of 50-60 Gy, as used in many phase III trials, result in substantial late morbidities and fail to control larger and node-positive tumours. Technological advances in radiation therapy are improving patient outcomes and quality of life, and should be applied to patients with SCCA. Modern techniques such as intensity-modulated radiotherapy (IMRT), rotational IMRT, image-guided radiotherapy using cone-beam CT, and stereotactic techniques have enabled smaller margins and highly conformal plans, resulting in decreased radiation doses to the organs at risk and ensuring a shorter overall treatment time. In this Perspectives article, the use of novel approaches to target delineation, optimized radiotherapy techniques, adaptive radiotherapy, dose-escalation with external-beam radiotherapy (EBRT) or brachytherapy, and the potential for modified fractionation are discussed in the context of SCCA.

Radiation Effects in the Mediastinum and Surroundings: Imaging Findings and Complications

Radiotherapy is one of the cornerstones for treatment of patients with cancer. Although advances in radiotherapy technology have considerably improved radiation delivery, potential adverse effects are still common. Postradiation changes to the mediastinum can include different structures such as the heart, great vessels, and esophagus. The purpose of the article was to illustrate the expected variety of changes to the mediastinum and adjacent lung resulting from external beam radiotherapy and radiotherapy-induced complications to the mediastinum and to discuss different radiotherapy delivery techniques.

Cost calculation: a necessary step towards widespread adoption of advanced radiotherapy technology

ABSTRACTRadiotherapy costs are an often underestimated component of the economic assessment of new radiotherapy treatments and technologies. That the radiotherapy budget only consumes a finite part of the total cancer and healthcare budget does not relieve us from our responsibility to balance the extra costs to the additional benefits of new, more advanced, but typically also more expensive treatments we want to deliver. Yet, in contrast to what is the case for oncology drugs, literature evidence remains limited, as well for economic evaluations comparing new radiotherapy interventions as for cost calculation studies. Even more cumbersome, the available costing studies in the field of radiotherapy fail to accurately capture the real costs of our treatments due to the large variation in cost inputs, in scope of the analysis, in costing methodology. And this is not trivial. Accurate resource cost accounting lays the basis for the further steps in health technology assessment leading to radiotherapy investments and reimbursement, at the local, the national and the worldwide level.In the current paper we review some evidence from the existing costing literature and discuss how such data can be used to support reimbursement setting and investment cases for new radiotherapy equipment and infrastructure.

Prevention and Management of Radiation-induced Late Gastrointestinal Toxicity

In the UK, about 90 000 cancer survivors will suffer from pelvic radiation disease (PRD) due to their curative treatment including radiotherapy. The National Cancer Survivorship Initiative aims to improve the understanding and management of PRD by the oncology community. This overview covers the prevention, investigation and treatment for late radiation-induced gastrointestinal symptoms in PRD. Multiple pharmacological and nutritional interventions have been studied, as prophylaxis for acute gastrointestinal toxicity (aiming to prevent late consequential effects), although predominantly only small randomised controlled trials have been conducted. These have produced mixed results, although promising signals for some agents have been observed. Evidence for the pharmacological prevention of late gastrointestinal toxicity is scarce. Even fewer randomised controlled trials have investigated the late gastrointestinal toxicity profile of advanced radiotherapy technologies. There are nationally agreed algorithms for the investigation and management of PRD, but a lack of awareness means patients still do not get referred appropriately. This overview outlines the management of radiation proctopathy and diarrhoea, and signposts other accessible resources. Finally, we provide recommendations for the management of late gastrointestinal symptoms in PRD and research in this field, especially the need for high-quality clinical trials.

Pregnancy associated nasopharyngeal carcinoma: A retrospective case-control analysis of maternal survival outcomes

BackgroundPregnancy-associated nasopharyngeal carcinoma (PANPC) has been associated with poor survival. Recent advances in radiation technology and imaging techniques, and the introduction of chemotherapy have improved survival in nasopharyngeal carcinoma (NPC); however, it is not clear whether these changes have improved survival in PANPC. Therefore, the purpose of this study was to compare five-year maternal survival in patients with PANPC and non-pregnant patients with NPC. MethodsAfter adjusting for age, stage and chemotherapy mode, we conducted a retrospective case-control study among 36 non-metastatic PANPC patients and 36 non-pregnant NPC patients (control group) who were treated at our institution between 2000 and 2010. ResultsThe median age of both groups was 30years (range, 23–35years); median follow-up for all patients was 70months. Locoregionally-advanced disease accounted for 83.3% of all patients with PANPC and 92.9% of patients who developed NPC during pregnancy. In both the PANPC and control groups, 31 patients (86.1%) received chemotherapy and all patients received definitive radiotherapy. The five-year rates for overall survival (70% vs. 78%, p=0.72), distant metastasis-free survival (79% vs. 76%, p=0.77), loco-regional relapse-free survival (97% vs. 91%, p=0.69) and disease-free survival (69% vs. 74%, p=0.98) were not significantly different between the PANPC and control groups. Multivariate analysis using a Cox proportional hazards model revealed that only N-classification was significantly associated with five-year OS. ConclusionThis study demonstrates that, in the modern treatment era, pregnancy itself may not negatively influence survival outcomes in patients with NPC; however, pregnancy may delay the diagnosis of NPC.

Does a too risk-averse approach to the implementation of new radiotherapy technologies delay their clinical use?

Radiotherapy is a generally safe treatment modality in practice; nevertheless, recent well-reported accidents also confirm its potential risks. However, this may obstruct or delay the introduction of new technologies and treatment strategies/techniques into clinical practice. Risks must be addressed and judged in a realistic context: risks must be assessed realistically. Introducing new technology may introduce new possibilities of errors. However, delaying the introduction of such new technology therefore means that patients are denied the potentially better treatment opportunities. Despite the difficulty in quantitatively assessing the risks on both sides of the possible choice of actions, including the "lost opportunity", the best estimates should be included in the overall risk-benefit and cost-benefit analysis. Radiotherapy requires a sufficiently high level of support for the safety, precision and accuracy required: radiotherapy development and implementation is exciting. However, it has been anxious with a constant awareness of the consequences of mistakes or misunderstandings. Recent history can be used to show that for introduction of advanced radiotherapy, the risk-averse medical physicist can act as an electrical fuse in a complex circuit. The lack of sufficient medical physics resource or expertise can short out this fuse and leave systems unsafe. Future technological developments will continue to present further safety and risk challenges. The important evolution of radiotherapy brings different management opinions and strategies. Advanced radiotherapy technologies can and should be safely implemented in as timely a manner as possible for the patient groups where clinical benefit is indicated.

Stereotactic Ablative Body Radiotherapy for Lung Cancer

Lung stereotactic ablative radiotherapy (SABR) is a method of delivering high ‘ablative’ doses of radiotherapy to tumours in the lung. It was developed at the Karolinska Institute in the early 1990s using the methods established in cranial radiosurgery with multiple beams prescribed to an isodose and using a custom designed stereotactic body frame for immobilisation. Since then, aligned with the advances in radiotherapy technology and techniques (e.g. four-dimensional computed tomography simulation and image-guided radiotherapy), there has been a rapid increase in the use of lung SABR for both early stage lung cancer and lung metastases. For peripheral primary lung cancers less than 5 cm in diameter, high rates of local control and low levels of acute and late toxicity are consistently reported in the published literature. Compared with historical control rates of stage I lung cancers treated with conventionally fractionated radiotherapy, SABR seems to offer higher rates of local control, lower levels of acute toxicity and a better quality of life after treatment. However, the full results of randomised controlled trials of SABR versus conventionally fractionated are awaited and will provide higher-level evidence. For central lung tumours, very high SABR doses can be associated with significant toxicity. Dose-adapted fractionation schedules seem to have much lower rates of toxicity and prospective trials, including the completed RTOG 0813 study and the on-going EORTC LUNGTEC study, should provide further evidence of safety and establish organ at risk tolerances. SABR can also be used for tumours metastatic to the lung with high rates of local control and is a reasonable alternative to surgery in selected patients. Going forward, prospective trials are underway to establish the safety and efficacy of SABR in oligometastatic disease. Population-based outcomes will be crucial in supporting/establishing SABR as the treatment of choice in medically inoperable patients with peripheral stage I lung cancers. Randomised phase III trials will hopefully extend the evidence base and show the safety and the utility of SABR in early central tumours and oligometastatic disease.

Development of phantom and methodology for 3D and 4D dose intercomparisons for advanced lung radiotherapy

There are few reported intercomparisons or audits of combinations of advanced radiotherapy methods, particularly for 4D treatments. As part of an evaluation of the implementation of advanced radiotherapy technology, a phantom and associated methods, initially developed for in-house commissioning and QA of 4D lung treatments, has been developed further with the aim of using it for end-to-end dose intercomparison of 4D treatment planning and delivery. The respiratory thorax phantom can house moving inserts with variable speed (breathing rate) and motion amplitude. In one set-up mode it contains a small ion chamber for point dose measurements, or alternatively it can hold strips of radiochromic film to measure dose distributions. Initial pilot and feasibility measurements have been carried out in one hospital to thoroughly test the methods and procedures before using it more widely across a range of hospitals and treatment systems. Overall, the results show good agreement between measured and calculated doses and distributions, supporting the use of the phantom and methodology for multi-centre intercomparisons. However, before wider use, refinements of the method and analysis are currently underway particularly for the film measurements.

Potential hazard due to induced radioactivity secondary to radiotherapy: the report of task group 136 of the American Association of Physicists in Medicine.

External-beam radiation therapy mostly uses high-energy photons (x-rays) produced by medical accelerators, but many facilities now use proton beams, and a few use fast-neutron beams. High-energy photons offer several advantages over lower-energy photons in terms of better dose distributions for deep-seated tumors, lower skin dose, less sensitivity to tissue heterogeneities, etc. However, for beams operating at or above 10 MV, some of the materials in the accelerator room and the radiotherapy patient become radioactive due primarily to photonuclear reactions and neutron capture, exposing therapy staff and patients to unwanted radiation dose. Some recent advances in radiotherapy technology require treatments using a higher number of monitor units and monitor-unit rates for the same delivered dose, and compared to the conventional treatment techniques and fractionation schemes, the activation dose to personnel can be substantially higher. Radiotherapy treatments with proton and neutron beams all result in activated materials in the treatment room. In this report, the authors review critically the published literature on radiation exposures from induced radioactivity in radiotherapy. They conclude that the additional exposure to the patient due to induced radioactivity is negligible compared to the overall radiation exposure as a part of the treatment. The additional exposure to the staff due to induced activity from photon beams is small at an estimated level of about 1 to 2 mSv y. This is well below the allowed occupational exposure limits. Therefore, the potential hazard to staff from induced radioactivity in the use of high-energy x-rays is considered to be low, and no specific actions are considered necessary or mandatory. However, in the spirit of the "As Low as Reasonably Achievable (ALARA)" program, some reasonable steps are recommended that can be taken to reduce this small exposure to an even lower level. The dose reduction strategies suggested should be followed only if these actions are considered reasonable and practical in the individual clinics. Therapists working with proton beam and neutron beam units handle treatment devices that do become radioactive, and they should wear extremity monitors and make handling apertures and boluses their last task upon entering the room following treatment. Personnel doses from neutron-beam units can approach regulatory limits depending on the number of patients and beams, and strategies to reduce doses should be followed.

Radiation-induced hemorrhagic cystitis.

To better understand the mechanism of radiation-induced hemorrhagic cystitis and the advantages and disadvantages of available treatment options for bladder hemorrhage as well as preventive measures. There have been several attempts recently to manage hemorrhagic cystitis with hyperbaric oxygen therapy, transurethral coagulation using Greenlight potassium-titanyl-phosphate laser and other different treatment modalities, but we still need more investigation on larger cohort studies. Hemorrhagic cystitis is an uncommon urological problem. It is most often caused by radiation therapy and cyclophosphamide, but can be associated with other contributing factors. Technological advances in radiation therapy have resulted in greater treatment efficacy, with significant reduction in side-effects such as hemorrhagic cystitis. Higher dose radiation treatment, however, is more often associated with problematic hemorrhagic cystitis. Treatment of hemorrhagic cystitis is multifactorial and can range from simple bladder irrigation to cystectomy with urinary diversion.

TU‐C‐16A‐01: Joint AAPM/SEFM/AMPR Educational Workshop On “Education of Radiotherapy Physicists”

This workshop is jointly organized by the AAPM, the Spanish (SEFM) and the Russian (AMPR) Medical Physics Societies, as part of formal educational exchange agreements signed by the AAPM with each one of these two societies.With the rapid technological advances in radiation therapy both for treatment and imaging, it is challenging how physics is taught to medical physicists practicing in radiation therapy. The main Objectives: of this workshop is to bring forth current status, challenges and issues related to education of radiation therapy physicists here in the US, Spain and Russia. Medical physicists from each one of these countries will present educational requirements of international recommendations and directives and analyze their impact on national legislations. Current and future educational models and plans for harmonization will be described. The role of universities, professional societies and examination boards, such as the American Board of Radiology, will be discussed. Minimum standards will be agreed upon.Learning Objectives: Review medical physics educational models supported by AAPM, SEFM, and AMPR. Discuss the role of governmental and non‐governmental organizations in elaborating and adopting medical physics syllabi. Debate minimum educational standards for medical physics education based on country‐specific resources.

SU‐E‐CAMPUS‐J‐04: Image Guided Radiation Therapy (IGRT): Review of Technical Standards and Credentialing in Radiotherapy Clinical Trials

Purpose:To review IGRT credentialing experience and unexpected technical issues encountered in connection with advanced radiotherapy technologies as implemented in RTOG clinical trials. To update IGRT credentialing procedures with the aim of improving the quality of the process, and to increase the proportion of IGRT credentialing compliance. To develop a living disease site‐specific IGRT encyclopedia.Methods:Numerous technical issues were encountered during the IGRT credentialing process. The criteria used for credentialing review were based on: image quality; anatomy included in fused data sets and shift results. Credentialing requirements have been updated according to the AAPM task group reports for IGRT to ensure that all required technical items are included in the quality review process. Implementation instructions have been updated and expanded for recent protocols.Results:Technical issues observed during the credentialing review process include, but are not limited to: poor quality images; inadequate image acquisition region; poor data quality; shifts larger than acceptable; no soft tissue surrogate. The updated IGRT credentialing process will address these issues and will also include the technical items required from AAPM: TG 104; TG 142 and TG 179 reports. An instruction manual has been developed describing a remote credentialing method for reviewers. Submission requirements are updated, including images/documents as well as facility questionnaire. The review report now includes summary of the review process and the parameters that reviewers check. We have reached consensus on the minimum IGRT technical requirement for a number of disease sites. RTOG 1311(NRG‐BR002A Phase 1 Study of Stereotactic Body Radiotherapy (SBRT) for the Treatment of Multiple Metastases) is an example, here; the protocol specified the minimum requirement for each anatomical sites (with/without fiducials).Conclusion:Technical issues are identified and reported. IGRT guidelines are updated, with the corresponding credentialing requirements. An IGRT encyclopedia describing site‐specific implementation issues is currently in development.

Increasing use of advanced radiation therapy technologies in the last 30 days of life among patients dying as a result of cancer in the United States.

We sought to analyze trends in radiation therapy (RT) technology use and costs in the last 30 days of life for patients dying as a result of cancer. We used the Surveillance, Epidemiology, and End Results (SEER) -Medicare and Texas Cancer Registry-Medicare databases to analyze claims data for 13,488 patients dying as a result of lung, breast, prostate, colorectal, melanoma, and pancreas cancers from 2000 to 2009. Logistic regression modeling was used to conduct adjusted analyses regarding influence of demographic, clinical, and health services variables on receipt of types of RT. Costs were calculated in 2009 US dollars. The proportion of patients treated with two-dimensional RT decreased from 74.9% of those receiving RT in the last 30 days of life in 2000 to 32.7% in 2009 (P < .001). Those receiving three-dimensional RT increased from 27.2% in 2000 to 58.5% in 2009 (P < .001). The proportion of patients treated with intensity-modulated radiation therapy in the last 30 days of life increased from 0% in 2000 to 6.2% in 2009 (P < .001), and those undergoing stereotactic radiosurgery increased from 0% in 2000 to 5.0% in 2009 (P < .001). The adjusted mean costs of per-patient RT services delivered in the last 30 days of life were higher in the years 2007 to 2009. Among patients receiving RT in the last month of life, there was a shift away from the simplest technique toward more advanced RT technologies. Studies are needed to ascertain whether these technology shifts improve palliative outcomes and quality of life for patients dying as a result of cancer who receive RT services.

Influence of conformal radiotherapy technique on survival after chemoradiotherapy for patients with stage III non‐small cell lung cancer in the National Cancer Data Base

Definitive chemoradiotherapy is a core treatment modality for patients with stage III non-small cell lung cancer (NSCLC). Although radiotherapy (RT) technologies have advanced dramatically, to the authors' knowledge relatively little is known regarding the importance of irradiation technique on outcome, particularly given the competing risk of distant metastasis. The National Cancer Data Base was used to determine predictors of overall survival (OS) in patients with AJCC stage III NSCLC who were treated with chemoradiotherapy, focusing on the importance of conformal RT (CRT). Patients with stage III NSCLC who were treated with chemoradiotherapy between 2003 and 2005 in the National Cancer Data Base were included. RT technique was defined as conventional, 3-dimensional-conformal, or intensity-modulated RT (IMRT), the latter 2 combined as CRT. Cox proportional hazards regression was performed for univariable and multivariable analyses of OS. The median, 3-year, and 5-year survival outcomes for the 13,292 patients were 12.9 months, 19%, and 11%, respectively. The 3-year and 5-year survival probabilities of patients receiving CRT versus no CRT were 22% versus 19% and 14% versus 11%, respectively (P < .0001). On multivariable analysis, CRT was found to be significantly associated with improved OS (hazards ratio, 0.89). This effect was confirmed on sensitivity analyses, including restricting the cohort to minimum 6-month survivors, young patients with stage IIIA disease, and propensity score-matching. Institutional academic status and patient volume were not found to be associated with OS. CRT was found to be independently associated with a survival advantage. These results reflect the importance of optimal locoregional therapy in patients with stage III NSCLC and provide motivation for further study of advanced RT technologies in patients with NSCLC.

Pilot dose intercomparisons of 3D and 4D advanced lung radiotherapy

s / Physica Medica 30 (2014) e16ee44 e26 Contemporary therapeutic radiation oncology treatments require the de- livery of highly localized doses of radiation to well defined target regions inside the patient. The efficacy of the radiation treatment, however, re- quires knowledge of the absorbed dose in the organ of interest to better than ±5% as there is a higher risk of local recurrence or complications with incorrect exposure. Furthermore, since it is inevitable that healthy organs and tissue will also be exposed during treatment, overexposure increases the risk of secondary cancers. International regulations [1, 2] have been introduced to adapt to the fast introduction of new radiotherapy technologies and demand an improve- ment of in vivo dosimetry. Ideally, a real-time in vivo dosimeter would measure absorbed doses during radiotherapy. Optical stimulated luminescent (OSL) dosimeters, using the high sensi- tive material Al2O3:C, have been successfully used for measuring whole body doses that result from exposure to high energetic photon and beta radiation. OSL dosimeters have also been introduced in medical dosim- etry of low and high LET beams [3, 4]. Al2O3:C detectors can also be used as real time dosemeters, because the emitted stimulated light can be guided via light fibers to a remotely placed photomultiplier tube. Furthermore, during exposure to ionizing radiation Al2O3:C emits radi- oluminescent light (RL), of which the intensity is proportional to the dose rate [5]. In this study, we investigated the dosimetric response of an optical fibre coupled Al203:C RL/OSL dosemeter prototype. In our prototype, a PMMA fibre is coupled to an Al2O3:C detector composed of microparticles of Al2O3:C with diameters ranging from 5 mm to 35 mm dissolved in a photo- curable polymer. The RL/OSL dosimeter prototype is a portable and robust instrument that has been developed for the routine assessment of patient exposure to ionizing radiation during radiotherapy treatments. The design principles of hardware and software are described elsewhere [6]. In this study, we present the results obtained using radioluminescence (RL) from Al2O3:C irradiated with a 6 MV linear accelerator (Compact, Elekta, Crawly) and preliminary results obtained using optically stimulated luminescence (OSL). The dose rate dependence was assessed by varying the photon flux (MU/ min) of the linac, effectively changing the pulse rate and keeping the dose per pulse fixed. It was found that the RL measured dose response demonstrated low dose-rate dependency, to within 1%. The dose response was found to be linear in a dose range from 0.1 up to a dose of 6 Gy, with reproducibility below 0.5%. The dosimeter is benchmarked by evaluating the ability to measure depth- dose distributions and lateral dose profiles accurately. RL derived dose profiles have been compared with dose profiles measured with a standard ion chamber (PTW). Depth-dose distributions in water were acquired for a 6 MV photon beam using a 10 10 cm2 field, set at 350 MU/min, corre- sponding with 3.5 Gy/min at 10 cm depth. All data have been normalized to the depth-dose maximum. The RL measured dose agreed with the ionization chamber measured dose to within 1% (1 SD) for depths from 0.5 to 20 cm. Lateral dose profile was set at 350 MU/min (3.5 Gy/min at depth 10 cm), using a 10x10 cm2 field size. Differences between measured RL and ion chamber are within 1.5% for de direct beam and 5% in the penumbra region. These results show that the RL/OSL detector system makes it suitable for measurements of depth and lateral dose distributions in clinical photon beams. Furthermore, basic characteristics of OSL in irradiated fibers with Al2O3:C for dosimetry in therapeutic 6 MV photon beam were investigated.

Survey of Advanced Radiation Technologies Used at Designated Cancer Care Hospitals in Japan

Our survey assessed the use of advanced radiotherapy technologies at the designated cancer care hospitals in Japan, and we identified several issues to be addressed. We collected the data of 397 designated cancer care hospitals, including information on staffing in the department of radiation oncology (e.g. radiation oncologists, medical physicists and radiation therapists), the number of linear accelerators and the implementation of advanced radiotherapy technologies from the Center for Cancer Control and Information Services of the National Cancer Center, Japan. Only 53% prefectural designated cancer care hospitals and 16% regional designated cancer care hospitals have implemented intensity-modulated radiotherapy for head and neck cancers, and 62% prefectural designated cancer care hospitals and 23% regional designated cancer care hospitals use intensity-modulated radiotherapy for prostate cancer. Seventy-four percent prefectural designated cancer care hospitals and 40% regional designated cancer care hospitals employ stereotactic body radiotherapy for lung cancer. Our multivariate analysis of prefectural designated cancer care hospitals which satisfy the institute's qualifications for advanced technologies revealed the number of radiation oncologists (P = 0.01) and that of radiation therapists (P = 0.003) were significantly correlated with the implementation of intensity-modulated radiotherapy for prostate cancer, and the number of radiation oncologists (P = 0.02) was correlated with the implementation of stereotactic body radiotherapy. There was a trend to correlate the number of medical physicists with the implementation of stereotactic body radiotherapy (P = 0.07). Only 175 (51%) regional designated cancer care hospitals satisfy the institute's qualification of stereotactic body radiotherapy and 76 (22%) satisfy that of intensity-modulated radiotherapy. Seventeen percent prefectural designated cancer care hospitals and 13% regional designated cancer care hospitals had a quality assurance committee. The numbers of radiation oncologists and other operating staff might be essential factors in the implementation of advanced radiotherapy technologies. Small proportions of regional designated cancer care hospitals satisfy the institute's qualifications of advanced technologies.

Medical Care And Bankruptcy: The Author Replies

Letters Health AffairsVol. 32, No. 10: Economic Trends & Quality Trade-Offs Medical Care And Bankruptcy: The Author RepliesScott Ramsey Affiliations Fred Hutchinson Cancer Research Center Seattle, Washington PUBLISHED:October 2013No Accesshttps://doi.org/10.1377/hlthaff.2013.0800AboutSectionsView articleView Full TextView PDFPermissions ShareShare onFacebookTwitterLinked InRedditEmail ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions View article"Medical Care And Bankruptcy: The Author Replies." Health Affairs, 32(10), p. 1856TOPICS Loading Comments... Please enable JavaScript to view the comments powered by Disqus. DetailsExhibitsReferencesRelated Article MetricsCitations: Crossref 1 History Published online 1 October 2013 Information Project HOPE—The People-to-People Health Foundation, Inc. PDF downloadCited byPromoting the Appropriate Use of Advanced Radiation Technologies in Oncology: Summary of a National Cancer Policy Forum WorkshopInternational Journal of Radiation Oncology*Biology*Physics, Vol. 97, No. 3

Evolution of advanced technologies in prostate cancer radiotherapy

Conventional treatment options for clinically localized, low-risk prostate cancer include radical prostatectomy, external-beam radiotherapy (EBRT) and low-dose-rate brachytherapy. Advances in image-guided radiotherapy (IGRT) since the 1980s, the development of intensity-modulated radiotherapy (IMRT) during the 1990s and evidence from radiobiological models--which support the use of high doses per fraction--have developed alongside novel advanced radiotherapy modalities that include high-dose-rate brachytherapy (HDR-BT), stereotactic body radiotherapy (SBRT) and proton beam therapy. The relationship between the outcomes of and toxicities experienced by patients with prostate cancer treated with HDR-BT, SBRT and particle-beam therapy should provide urologists and oncologists an understanding of the continually evolving technology in prostate radiotherapy. On the basis of published evidence, conventionally fractionated EBRT with IMRT is considered the standard of care over conventional 3D conformal radiotherapy, whereas HDR-BT boost is an acceptable treatment option for selected patients with intermediate-risk and high-risk prostate cancer. SBRT and proton therapy should not be used for patients (regardless of disease risk group) outside the setting of a clinical trial. Finally, comparative effectiveness research should be conducted to provide a framework for evaluating advanced radiotherapy technologies by comparing the benefits and harms of available therapeutic options to optimize the risk:benefit ratio and improve cost effectiveness.