National variation in the delivery of radiation oncology procedures in the non-facility-based setting.

PURPOSE: Though utilization of medical procedures has been shown to vary considerably across the United States, similar efforts to characterize variation in the delivery of radiation therapy (RT) procedures have not been forthcoming. Our aim was to characterize variation in the delivery of common RT procedures in the Medicare population. We hypothesized that delivery would vary significantly based on provider characteristics. METHODS: The Centers for Medicare and Medicaid Services (CMS) Physician and Other Supplier Public Use File was linked to the CMS Physician Compare (PC) database by physician NPI to identify and sum all treatment delivery charges submitted by individual radiation oncologists in the non-facility-based (NFB) setting in 2016. Multivariable logistic regression analysis was carried out to determine provider characteristics (gender, practice rurality, practice region, and years since graduation) that predicted for the delivery of 3D conformal RT (3DCRT), intensity modulated RT (IMRT), stereotactic body RT (SBRT), stereotactic radiosurgery (SRS), low dose rate (LDR) brachytherapy, and high dose rate (HDR) brachytherapy delivery in the Medicare patient population. The overall significance of categorical variables in the multivariable logistic regression model was assessed by the likelihood ratio test (LRT). RESULTS: In total, 1,802 physicians from the NFB practice setting were analyzed. Male gender predicted for greater LDR brachytherapy delivery (OR 8.19, 95% CI 2.58-26.05, p < 0.001), but not greater delivery of other technologies. Metropolitan practice was the only predictor for greater HDR brachytherapy utilization (OR 12.95, 95% CI 1.81-92.60, p = 0.01). Practice region was predictive of the delivery of 3DCRT, SRS and SBRT (p < 0.01, p < 0.001, and p < 0.001, respectively). With the Northeast as the reference region, 3DCRT was more likely to be delivered by providers in the South (OR 1.33, 95% CI 1.09-1.62, p < 0.01) and the West (OR 1.38, 95% CI 1.11-1.71, p < 0.01). At the same time, SRS use was less likely in the Midwest (OR 0.71, 95% CI 0.55-0.91, p < 0.01), South (OR 0.49, 95% CI 0.40-0.61, p < 0.001), and West (OR 0.43, 95% CI 0.34-0.55, p < 0.001). SBRT, on the other hand, was more commonly utilized in the Midwest (OR 2.63, 95% CI 1.13-6.13, p = 0.03), South (OR 3.44, 95% CI 1.58-7.49, p < 0.01), and West (OR 4.87, 95% CI 2.21-10.72, p < 0.001). HDR brachytherapy use was also more likely in the Midwest (OR 1.97, 95% CI 1.11-3.49, p = 0.02) and West (OR 1.87, 95% CI 1.08-3.24, p = 0.03). While the degree held by the billing physician did not predict for delivery of a given procedure, greater years since graduation was related to decreased likelihood of SBRT use (OR 0.98, 95% CI 0.96-0.99, p < 0.001) and increased likelihood of LDR brachytherapy use (OR 1.02, 95% CI 1.00-1.04, p = 0.02). CONCLUSIONS: Substantial geographic variation in the use of specific RT technologies was identified. The degree to which this variation reflects effective care, preference-sensitive care, or supply-sensitive care warrants further investigation.

Photon and Proton Radiation Therapy Utilization in a Population of More Than 100 Million Commercially Insured Patients.

PURPOSE: To characterize the changes in the use of radiation therapy (RT), specifically proton beam radiation therapy (PBRT), among adult and pediatric patients over a 11-year period in a very large population of insured patients. METHODS AND MATERIALS: We conducted a retrospective analysis of the OptumLabs Data Warehouse claims database of more than 100 million insured US enrollees. Descriptive analyses were undertaken to evaluate the characteristics of patients receiving RT from 2002 to 2012. RESULTS: There were 474,533 patients treated with RT from 2002 to 2012. The percentage of patients treated with 3-dimensional conformal radiation therapy, 2-dimensional RT/brachytherapy, intensity modulated radiation therapy (IMRT), stereotactic body radiation therapy (SBRT), and PBRT was 34.5%, 63.4%, 2.1%, 0.0%, and 0.1% and 40.4%, 36.0%, 21.9%, 1.1%, and 0.6% in 2002 and 2012, respectively. The greatest increase in utilization was of IMRT for prostate cancer, growing from 3.5% to 64.0%. For non-prostate cancer adults, IMRT use grew from 1.7% to 16.4%. For children, PBRT utilization increased from 0.3% to 9.7%. For prostate cancer patients, PBRT increased from 0.0% to 2.6%. For all patients, advanced technology (SBRT and PBRT) use was very low at <2%, versus 22% for IMRT. CONCLUSIONS: This is the largest and most geographically diverse description of RT utilization. Proton beam RT utilization remains very low and has had little impact on overall RT utilization compared with IMRT. The largest shift has occurred in IMRT for prostate cancer. Our findings indicate that overall utilization of proton therapy has been low and that its use has likely had little impact on national expenditures on cancer care in the current environment.

Commissioning of beam shaper applicator for conformal intraoperative electron radiotherapy.

Beam shaper is a newly designed device for beam shaping in IOERT. The aim of this study is evaluating the performance of this device for conformal IOERT and preparing it for clinical applications. Dosimetric characteristics for different combinations of energy/field size were determined by ionometric dosimetry, film dosimetry and Monte Carlo simulation. Desirable dosimetric characteristics of beam shaper make it a useful tool for conformal IOERT. Usability of Monte Carlo simulation in any clinical setup of beam shaper was demonstrated.

Quantitative Assessment of Breast Cosmetic Outcome After Whole-Breast Irradiation.

PURPOSE: To measure, by quantitative analysis of digital photographs, breast cosmetic outcome within the setting of a randomized trial of conventionally fractionated (CF) and hypofractionated (HF) whole-breast irradiation (WBI), to identify how quantitative cosmesis metrics were associated with patient- and physician-reported cosmesis and whether they differed by treatment arm. METHODS AND MATERIALS: From 2011 to 2014, 287 women aged ≥40 with ductal carcinoma in situ or early invasive breast cancer were randomized to HF-WBI (42.56 Gy/16 fractions [fx] + 10-12.5 Gy/4-5 fx boost) or CF-WBI (50 Gy/25 fx + 10-14 Gy/5-7 fx). At 1 year after treatment we collected digital photographs, patient-reported cosmesis using the Breast Cancer Treatment and Outcomes Scale, and physician-reported cosmesis using the Radiation Therapy Oncology Group scale. Six quantitative measures of breast symmetry, labeled M1-M6, were calculated from anteroposterior digital photographs. For each measure, values closer to 1 imply greater symmetry, and values closer to 0 imply greater asymmetry. Associations between M1-M6 and patient- and physician-reported cosmesis and treatment arm were evaluated using the Kruskal-Wallis test. RESULTS: Among 245 evaluable patients, patient-reported cosmesis was strongly associated with M1 (vertical symmetry measure) (P<.01). Physician-reported cosmesis was similarly correlated with M1 (P<.01) and also with M2 (vertical symmetry, P=.01) and M4 (horizontal symmetry, P=.03). At 1 year after treatment, HF-WBI resulted in better values of M2 (P=.02) and M3 (P<.01) than CF-WBI; treatment arm was not significantly associated with M1, M4, M5, or M6 (P≥.12). CONCLUSIONS: Quantitative assessment of breast photographs reveals similar to improved cosmetic outcome with HF-WBI compared with CF-WBI 1 year after treatment. Assessing cosmetic outcome using these measures could be useful for future comparative effectiveness studies and outcome reporting.

Cost-Effectiveness Analysis of Radiation Therapy Versus Transoral Robotic Surgery for Oropharyngeal Squamous Cell Carcinoma.

PURPOSE: The objective of this study was to compare the cost-effectiveness of transoral robotic surgery (TORS) versus the standard treatment modality for oropharyngeal squamous cell carcinoma (OPSCC), radiation therapy (RT), in a subset of patients with early-stage OPSCC. METHODS AND MATERIALS: We developed a microsimulation state-transition model associated with RT and TORS for patients with clinically staged T1N0M0 to T2N1M0 OPSCC. Transition probabilities, utilities, and costs for each health state were estimated from recently published data and discounted by 3% annually over a lifetime time horizon. Model outcomes included lifetime costs (in 2014 US dollars), health benefits (quality-adjusted life-years [QALYs]), and cost-effectiveness ratios from a societal perspective. RESULTS: Under base-case assumptions, TORS was associated with modest gains in QALYs. RT yielded 10.43 QALYs at a cost of $123,410 per patient, whereas TORS yielded 11.10 QALYs at a cost of $178,480. This resulted in an incremental cost-effectiveness ratio of $82,190/QALY gained. The incremental cost-effectiveness ratio was most sensitive to the need for adjuvant therapy, cost of late toxicity, age at diagnosis, disease state utilities, and discount rate. Accounting for joint parameter uncertainty, RT had a higher probability of demonstrating a cost-effective profile compared with TORS, at 54% compared with 46%. CONCLUSIONS: By use of standard benchmarks for cost-effectiveness in the United States, TORS may be a cost-effective alternative for the subset of patients with early-stage OPSCC but demonstrates considerable sensitivity to assumptions around quality of life.

Análise de custo-efetividade da técnica de IMRT para o tratamento do câncer de próstata localizado / Cost-effectiveness analysis of the IMRT technique for the treatment of localized prostate cancer

De acordo com os dados do Instituto Nacional de Câncer José Alencar Gomes da Silva (INCA), foram esperados, no Brasil, 61.200 novos casos de câncer de próstata para o ano de 2016. Estabelecido o diagnóstico, as opções terapêuticas são consideradas e se baseiam no estadiamento, dosagem do antígeno prostático específico (PSA) e escore histológico de Gleason. Segundo as diretrizes diagnósticas e terapêuticas do adenocarcinoma de próstata publicadas (2015), a técnica de radioterapia de intensidade modulada (IMRT) apresenta benefício no controle da doença e a menor probabilidade de toxicidade. Este trabalho teve como objetivo analisar a custo-efetividade da técnica de IMRT, na perspectiva do SUS, para o tratamento do câncer de próstata localizado, comparada com a técnica conformacional (3DRT). Foi construído um modelo de Markov e, uma coorte hipotética de homens de 65 a 70 anos foi acompanhada por 10 anos. A medida de desfecho clínico foram os anos de vida ajustados para qualidade (QALY). Os custos levantados se basearam nos valores da tabela APAC para um tratamento na dose de 74 a 76 Gy. Análise de sensibilidade probabilística baseada em simulação de Monte Carlo a fim de construir um limiar de aceitabilidade para incorporação da tecnologia em questão foi desenvolvida. O uso da tecnologia IMRT proporcionou um incremento de 0,79 QALY, mas não se mostrou custo-efetiva em relação aos pacientes que receberam radioterapia pela 3DRT. A IMRT apresentou uma razão de custoefetividade incremental de R$10.580,98/QALY. Ao considerar um limiar de aceitabilidade de três vezes o produto interno bruto (PIB) per capita, segundo recomendação da Organização Mundial de Saúde (2011), estimado em R$ 86.628,00/QALY, para 2016, o cenario para a incorporaçao dessa tecnologia se apresenta favoravel. A probabilidade do IMRT ser custo-efetiva foi de 72,5% para limiares de aceitabilidade de R$15.000,00

According to data from the Coordination of Prevention and Surveillance of the National Cancer Institute José Alencar Gomes da Silva (NCI) 61,200 new cases of prostate cancer were expected in Brazil in 2016. Once the diagnosis is established, the therapeutic options are considered according to risk groups described by D'Amico (1998), which are based on staging, prostate-specific antigen (PSA) and Gleason score. For localized prostate tumors, and for all risk groups, radiotherapy is indicated. According to the diagnostic and therapeutic guideline of prostate adenocarcinoma published in October 2015, the intensity modulated radiotherapy (IMRT) technique has a benefit in controlling the disease and the lower probability of toxicity. According to this premise, this study aimed to analyze the costeffectiveness of the IMRT technique, from the perspective of SUS, for the treatment of localized prostate cancer, compared with three-dimensional technique (3DRT). A mathematical model based on Markov models was constructed and a hypothetical cohort of men aged 65 to 70 years was followed up for 10 years. A probabilistic sensitivity analysis was performed based on Monte Carlo simulation to construct a threshold of acceptability for incorporation of the technology in question. As a result of the study, the use of IMRT technology provided a 0.79-year increase in quality-adjusted life years (QALY), but was not cost-effective compared to patients who received radiotherapy using the 3DRT. The IMRT presented an incremental cost-effectiveness ratio of R $ 10,580.98 / QALY. Based on a threshold of three times the per capita GDP, according to the WHO recommendation (2011), calculated at R $ 86,628.00 / QALY for 2016, the scenario for the incorporation of this technology is favorable. If a threshold of acceptability of R $ 28,876 is considered equivalent to a GDP per capita, the probability of IMRT being cost-effective is 72%

Emerging radiotherapy technology in a developing country: A single Brazilian institution assessment of stereotactic body radiotherapy application.

OBJECTIVE:: To provide a quantitative profile of the indications and use of stereotactic body radiotherapy (SBRT) in a developing country oncology-based institution. In addition, to describe the patients' and treatment characteristics, and to provide a temporal analysis. METHOD:: SBRT patients treated from 2007 to 2015 were retrospectively evaluated by two independently investigators. Data were stratified and compared in two periods: first experience (FE) (May 2007 to April 2011), and following experience (FollowE) (May 2011 to April 2015). The following parameters were compared between the groups: total number of treated patients and lesions, treatment site, additional image fusion used, formal protocol adoption, and SBRT planning technique. RESULTS:: One hundred and seventy-six (176) patients with 191 lesions were treated: 34 (18%) lesions in the FE and 157 (82%) lesions in FollowE. The majority of lesions were metastases (60.3%), and lung (60.2%) was the most common treatment site, followed by spine (31%), and others (8.8%). An average of 1.4 (±0.6) additional imaging exams for delineation was performed. Conformal 3D radiotherapy planning technique was used in 64.4%, and intensity modulated radiotherapy (IMRT) or volumetric-modulated arc therapy (VMAT) in the remaining 35.6% (p=0.0001). Higher rates of curative treatments were observed in FE, as well as more lung lesions, patients ≥ 70 years, 3D conformal, number of additional images and ECOG 0, and all presented p<0.05. The global rate of protocol statement was 79%, lung treatment being the most stated. CONCLUSION:: SBRT application is rapidly increasing in our setting. Treatment sites and planning techniques are becoming more diversified and complex.

Emerging radiotherapy technology in a developing country: A single Brazilian institution assessment of stereotactic body radiotherapy application / Tecnologias emergentes em radioterapia em um país em desenvolvimento: perfil do uso de radiocirurgia extracraniana em uma instituição filantrópica privada

Summary Objective: To provide a quantitative profile of the indications and use of stereotactic body radiotherapy (SBRT) in a developing country oncology-based institution. In addition, to describe the patients' and treatment characteristics, and to provide a temporal analysis. Method: SBRT patients treated from 2007 to 2015 were retrospectively evaluated by two independently investigators. Data were stratified and compared in two periods: first experience (FE) (May 2007 to April 2011), and following experience (FollowE) (May 2011 to April 2015). The following parameters were compared between the groups: total number of treated patients and lesions, treatment site, additional image fusion used, formal protocol adoption, and SBRT planning technique. Results: One hundred and seventy-six (176) patients with 191 lesions were treated: 34 (18%) lesions in the FE and 157 (82%) lesions in FollowE. The majority of lesions were metastases (60.3%), and lung (60.2%) was the most common treatment site, followed by spine (31%), and others (8.8%). An average of 1.4 (±0.6) additional imaging exams for delineation was performed. Conformal 3D radiotherapy planning technique was used in 64.4%, and intensity modulated radiotherapy (IMRT) or volumetric-modulated arc therapy (VMAT) in the remaining 35.6% (p=0.0001). Higher rates of curative treatments were observed in FE, as well as more lung lesions, patients ≥ 70 years, 3D conformal, number of additional images and ECOG 0, and all presented p<0.05. The global rate of protocol statement was 79%, lung treatment being the most stated. Conclusion: SBRT application is rapidly increasing in our setting. Treatment sites and planning techniques are becoming more diversified and complex.

Resumo Objetivo: realizar uma análise quantitativa das indicações e do uso de SBRT (stereotactic body radiotherapy) em uma instituição filantrópica. Além disso, descrever temporalmente as características dos pacientes e tratamentos. Método: retrospectivamente, foram coletados, por dois investigadores independentes, os dados de todos os pacientes tratados com SBRT na instituição no período de maio de 2007 a fevereiro de 2015. Dados foram estratificados e comparados em dois períodos: inicial (P1) (maio de 2007 a abril de 2011) e período seguinte (P2) (maio de 2011 a abril de 2015). Os seguintes parâmetros foram comparados entre os grupos: número total de pacientes e lesões tratadas, local de tratamento, uso de imagens adicionais, adoção formal de protocolo e técnica de planejamento. Resultados: foram avaliados 176 pacientes e 191 lesões, sendo 34 (18%) no P1 e 157 (82%) no P2, tratados com SBRT. A maioria das lesões eram metastáticas (60,3%), sendo pulmão o sítio mais prevalente, contabilizando 115/191 (60,2%) lesões, seguida de lesões ósseas (30,8%). Uma média de 1,4 (±0,6) exame de imagem adicional foi usada para o delineamento. Uso formal de protocolo/recomendações foi descrito em 79% das lesões. A técnica 3D-conformada (3DCRT - three-dimensional conformal radiotherapy) foi a mais utilizada para planejamento [123/191 (64,4%) lesões] quando comparada à intensidade modulada e ao arco dinâmico (p=0.0001). O P1 esteve associado a maior número de lesões primárias tratadas (OR 2,09; p=0,0005), lesões pulmonares (OR 3,85; p=0,0198), pacientes ≥ 70 anos (OR 2,77; p=0,0005), uso de planejamento 3D (OR 16; p=0,0001), menor uso de imagens adicionais [0 ou 1 (versus > 1)] (OR 7,5; p=0,0001) e ECOG 0 (vs. > 0) (OR 0,21; p=0,0431). Conclusão: o uso de SBRT aumentou ao longo do tempo na instituição. No P2, notou-se uma evolução técnica, com indicações mais diferenciadas, maior uso de imagens auxiliares para definição do alvo e técnicas de planejamento mais sofisticadas.

[Intensity modulated radiotherapy for head and neck cancers: ethics and patients selection]. / Radiothérapie conformationnelle avec modulation d'intensité dans les cancers de la sphère ORL : éthique et sélection des patients.

PURPOSE: Intensity modulated radiotherapy (IMRT) allows a better coverage of the target volume and a better saving of organs at risk with a decrease of toxicity in head and neck cancers. It requires more human labor and materials compared to conformational radiotherapy. If they are insufficient, a selection of the patients receiving IMRT may be necessary, raising an ethical problem. MATERIAL AND METHODS: We collected the motives guiding the choice of the technique of radiotherapy for head and neck cancers during a month of physicists' shortage. RESULTS: Nineteen patients received IMRT and eight conformational radiotherapy. Conformational irradiation was chosen in palliative and postsurgery treatments, to reduce delay, in laryngeal tumors and re-irradiation. IMRT was preferred for complex target volumes and the localizations at risk of important xerostomia following conformational radiotherapy. These choices were confronted with the bioethics criteria of Beauchamp and Childress. The beneficence justified the use of IMRT or conformational radiotherapy depending on the circumstances. The non-maleficence attempted to decrease the toxicity with IMRT. Justice was questioned by the selection. The autonomy of patients was not totally respected in the choice. CONCLUSION: To help in the choice of the patients receiving an IMRT in a crisis situation, we proposed a hierarchical organization of selection criteria: complex volumes close to critical organs at risk, localization with high risk of xerostomia, long life expectancy and postoperative delay constraints.

Internal scatter, the unavoidable major component of the peripheral dose in photon-beam radiotherapy.

In clinical photon beams, the dose outside the geometrical field limits is produced by photons originating from (i) head leakage, (ii) scattering at the beam collimators and the flattening filter (head scatter) and (iii) scattering from the directly irradiated region of the patient or phantom (internal scatter). While the first two components can be modified, e.g. by reinforcement of shielding components or by re-modeling the filter system, internal scatter remains an unavoidable contributor to the peripheral dose. Its relative magnitude compared to the other components, its numerical variation with beam energy, field size and off-axis distance as well as its spectral distribution are evaluated in this study. We applied a detailed Monte Carlo (MC) model of our 6/15 MV Siemens Primus linear accelerator beam head, provided with ideal head leakage shielding conditions (multi-leaf collimator without gaps) to assess the head scatter contribution. Experimental values obtained under real shielding conditions were used to evaluate the head leakage contribution. It was found that the MC-computed internal scatter doses agree with the results of our previous measurements, that internal scatter is the major contributor to the peripheral dose in the near periphery while head leakage prevails in the far periphery, and that the lateral decline of the internal scatter dose can be represented by the sum of two exponentials, with an asymptotic tenth value of 18 to 19 cm. Internal scatter peripheral doses from various elementary beams are additive, so that their sum increases approximately in proportion with field size. The ratio between normalized internal scatter doses at 6 and 15 MV is approximately 2:1. The energy fluence spectra of the internal scatter component at all points of interest outside the field have peaks near 500 keV. The fact that the energy-shifted internal scatter constitutes the major contributor to the dose in the near periphery has a general bearing for dosimetry, i.e. for energy-dependent detector responses and dose conversion factors, for the relative biological effectiveness and for second primary malignancy risk estimates in the peripheral region.

Changes in initial treatment for prostate cancer among Medicare beneficiaries, 1999-2007.

PURPOSE: In the absence of evidence from large clinical trials, optimal therapy for localized prostate cancer remains unclear; however, treatment patterns continue to change. We examined changes in the management of patients with prostate cancer in the Medicare population. METHODS AND MATERIALS: We conducted a retrospective claims-based analysis of the use of radiation therapy, surgery, and androgen deprivation therapy in the 12 months after diagnosis of prostate cancer in a nationally representative 5% sample of Medicare claims. Patients were Medicare beneficiaries 67 years or older with incident prostate cancer diagnosed between 1999 and 2007. RESULTS: There were 20,918 incident cases of prostate cancer between 1999 and 2007. The proportion of patients receiving androgen deprivation therapy decreased from 55% to 36%, and the proportion of patients receiving no active therapy increased from 16% to 23%. Intensity-modulated radiation therapy replaced three-dimensional conformal radiation therapy as the most common method of radiation therapy, accounting for 77% of external beam radiotherapy by 2007. Minimally invasive radical prostatectomy began to replace open surgical approaches, being used in 49% of radical prostatectomies by 2007. CONCLUSIONS: Between 2002 and 2007, the use of androgen deprivation therapy decreased, open surgical approaches were largely replaced by minimally invasive radical prostatectomy, and intensity-modulated radiation therapy replaced three-dimensional conformal radiation therapy as the predominant method of radiation therapy in the Medicare population. The aging of the population and the increasing use of newer, higher-cost technologies in the treatment of patients with prostate cancer may have important implications for nationwide health care costs.

Impact of the calculation resolution of AAA for small fields and RapidArc treatment plans.

PURPOSE: To investigate the impact of the calculation resolution of the anisotropic analytical algorithms (AAA) for a variety of small fields in homogeneous and heterogeneous media and for RapidArc plans. METHODS: Dose distributions calculated using AAA version 8.6.15 (AAA8) and 10.0.25 (AAA10) were compared to measurements performed with GafChromic EBT film, using phantoms made of polystyrene or a combination of polystyrene and cork. The accuracy of the algorithms calculated using grid resolutions of 2.5 and 1.0 mm was investigated for different field sizes, and for a limited selection of RapidArc plans (head and neck, small meningioma, and lung). Additional plans were optimized to create excessive multileaf collimator modulation and measured on a homogenous phantom. Gamma evaluation criterion of 3% dose difference and 2- or 1-mm distance to agreement (DTA) were applied to evaluate the accuracy of the algorithms. RESULTS: For fields < or = 3 x 3 cm2, both versions of AAA predicted lower peak doses and broader penumbra widths than the measurements. However, AAA10 and a finer calculation grid improved the agreement. For RapidArc plans with many small multileaf collimator (MLC) segments and relatively high number of monitor units (MU), AAA8 failed to identify small dose peaks within the target. Both versions performed better in polystyrene than in cork. In homogeneous cork layers, AAA8 underestimated the average target dose for a clinical lung plan. This was improved with AAA10 calculated using a 1 mm grid. CONCLUSIONS: AAA10 improves the accuracy of dose calculations, and calculation grid of 1.0 mm is superior to using 2.5 mm, although calculation times increased by factor of 5. A suitable upper MU constraint should be assigned during optimization to avoid plans with high modulation. For plans with a relative high number of monitor units, calculations using 1 mm grid resolution are recommended. For planning target volume (PTV) which contains relatively large area of low density tissue, users should be aware of possible dose underestimation in the low density region and recalculation with AAA10 grid 1.0 mm is recommended.

Technological advancements and error rates in radiation therapy delivery.

PURPOSE: Technological advances in radiation therapy (RT) delivery have the potential to reduce errors via increased automation and built-in quality assurance (QA) safeguards, yet may also introduce new types of errors. Intensity-modulated RT (IMRT) is an increasingly used technology that is more technically complex than three-dimensional (3D)-conformal RT and conventional RT. We determined the rate of reported errors in RT delivery among IMRT and 3D/conventional RT treatments and characterized the errors associated with the respective techniques to improve existing QA processes. METHODS AND MATERIALS: All errors in external beam RT delivery were prospectively recorded via a nonpunitive error-reporting system at Brigham & Women's Hospital/Dana Farber Cancer Institute. Errors are defined as any unplanned deviation from the intended RT treatment and are reviewed during monthly departmental quality improvement meetings. We analyzed all reported errors since the routine use of IMRT in our department, from January 2004 to July 2009. Fisher's exact test was used to determine the association between treatment technique (IMRT vs. 3D/conventional) and specific error types. Effect estimates were computed using logistic regression. RESULTS: There were 155 errors in RT delivery among 241,546 fractions (0.06%), and none were clinically significant. IMRT was commonly associated with errors in machine parameters (nine of 19 errors) and data entry and interpretation (six of 19 errors). IMRT was associated with a lower rate of reported errors compared with 3D/conventional RT (0.03% vs. 0.07%, p = 0.001) and specifically fewer accessory errors (odds ratio, 0.11; 95% confidence interval, 0.01-0.78) and setup errors (odds ratio, 0.24; 95% confidence interval, 0.08-0.79). CONCLUSIONS: The rate of errors in RT delivery is low. The types of errors differ significantly between IMRT and 3D/conventional RT, suggesting that QA processes must be uniquely adapted for each technique. There was a lower error rate with IMRT compared with 3D/conventional RT, highlighting the need for sustained vigilance against errors common to more traditional treatment techniques.

Predictors of IMRT and conformal radiotherapy use in head and neck squamous cell carcinoma: a SEER-Medicare analysis.

PURPOSE: The extent to which new techniques for the delivery of radiotherapy for head and neck squamous cell carcinoma (HNSCC) have diffused into clinical practice is unclear, including the use of 3-dimensional conformal RT (3D-RT) and intensity-modulated radiation therapy (IMRT). METHODS AND MATERIALS: Using the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database, we identified 2,495 Medicare patients with Stage I-IVB HNSCC diagnosed at age 65 years or older between 2000 and 2005 and treated with either definitive (80%) or adjuvant (20%) radiotherapy. Our primary aim was to analyze the trends and predictors of IMRT use over this time, and the secondary aim was a similar description of the trends and predictors of conformal radiotherapy (CRT) use, defined as treatment with either 3D-RT or IMRT. RESULTS: Three hundred sixty-four (15%) patients were treated with IMRT, and 1,190 patients (48%) were treated with 3D-RT. Claims for IMRT and CRT rose from 0% to 33% and 39% to 86%, respectively, between 2000 and 2005. On multivariable analysis, IMRT use was associated with SEER region (West 18%; Northeast 11%; South 12%; Midwest 13%), advanced stage (advanced, 21%; early, 9%), non-larynx site (non-larynx, 23%; larynx, 7%), higher median census tract income (highest vs. lowest quartile, 18% vs. 10%), treatment year (2003-2005, 31%; 2000-2002, 6%), use of chemotherapy (26% with; 9% without), and higher radiation oncologist treatment volume (highest vs. lowest tertile, 23% vs. 8%). With CRT as the outcome, only SEER region, treatment year, use of chemotherapy, and increasing radiation oncologist HNSCC volume were significant on multivariable analysis. CONCLUSIONS: The use of IMRT and CRT by Medicare beneficiaries with HNSCC rose significantly between 2000 and 2005 and was associated with both clinical and non-clinical factors, with treatment era and radiation oncologist HNSCC treatment volume serving as the strongest predictors of IMRT use.

Monte Carlo simulation of the effect of miniphantom on in-air output ratio.

PURPOSE: The aim of the study was to quantify the effect of miniphantoms on in-air output ratio measurements, i.e., to determine correction factors for in-air output ratio. METHODS: Monte Carlo (MC) simulations were performed to simulate in-air output ratio measurements by using miniphantoms made of various materials (PMMA, graphite, copper, brass, and lead) and with different longitudinal thicknesses or depths (2-30 g/cm2) in photon beams of 6 and 15 MV, respectively, and with collimator settings ranging from 3 x 3 to 40 x 40 cm2. EGSnrc and BEAMnrc (2007) software packages were used. Photon energy spectra corresponding to the collimator settings were obtained from BEAMnrc code simulations on a linear accelerator and were used to quantify the components of in-air output ratio correction factors, i.e., attenuation, mass energy absorption, and phantom scatter correction factors. In-air output ratio correction factors as functions of miniphantom material, miniphantom longitudinal thickness, and collimator setting were calculated and compared to a previous experimental study. RESULTS: The in-air output ratio correction factors increase with collimator opening and miniphantom longitudinal thickness for all the materials and for both energies. At small longitudinal thicknesses, the in-air output ratio correction factors for PMMA and graphite are close to 1. The maximum magnitudes of the in-air output ratio correction factors occur at the largest collimator setting (40 x 40 cm2) and the largest miniphantom longitudinal thickness (30 g/cm2): 1.008 +/- 0.001 for 6 MV and 1.012 +/- 0.001 for 15 MV, respectively. The MC simulations of the in-air output ratio correction factor confirm the previous experimental study. CONCLUSIONS: The study has verified that a correction factor for in-air output ratio can be obtained as a product of attenuation correction factor, mass energy absorption correction factor, and phantom scatter correction factor. The correction factors obtained in the present study can be used in studies involving in-air output ratio measurements using miniphantoms.

Hypofractionated whole-breast radiotherapy: impact on departmental waiting times and cost.

Conventionally fractionated breast radiation therapy is delivered over 5-6 weeks. Randomised evidence has shown that hypofractionated whole-breast radiotherapy (HWBRT) over 3 weeks results in similar local control without increased toxicity. HWBRT is not standard practice in Australia for all eligible women. We examined the effect of using HWBRT (for eligible patients) on waiting lists and monetary costs. We identified factors associated with prescribing HWBRT. The Princess Alexandra Hospital Radiation Oncology Database was searched for all women with breast cancer treated with adjuvant radiotherapy in 2008. Included patients had undergone breast conserving surgery and had T1-2N0 tumours with negative margins. Women with large breasts and those receiving nodal irradiation were excluded. The outcome evaluated was fractionation schedule. Patient, tumour and treatment factors associated with the use of HWBRT were examined. The impact on departmental resources and health-care costs were calculated assuming the entire cohort received HWBRT. Two hundred seventy-nine patients met the inclusion criteria. Sixty-seven (24%) of these patients were treated with HWBRT. Compared with the conventionally fractionated breast radiation therapy group, the HWBRT group were older (median 69 vs. 54 years; P < 0.001) and more likely to have smaller tumours (12 mm vs. 15 mm; P = 0.02). Had all eligible patients received HWBRT an extra 14 patients each month could be treated and health-care costs would be reduced by 24%. HWBRT was more frequently prescribed in older women with small tumours. More widespread use of HWBRT would allow significantly more patients to be treated each month with considerable cost savings.

'GAP' in radiotherapy services in Australia and New Zealand in 2009.

AIM: In this study we estimated (a) the number of linear accelerators required in Australia and New Zealand to achieve a 52.3% treatment rate; (b) the 'GAP' between the actual and required number of linear accelerators; c) the number of persons not treated (PNT), premature deaths (PD) and years of life lost (YLL) as a result of the 'GAP'; and (d) to review the actions being taken by health jurisdictions in Australia and in New Zealand to address the 'GAP' and reach the 52.3% treatment rate. MATERIAL AND METHODS: The actual number of fully staffed and operating linear accelerators (A) in Australian and New Zealand was obtained from a survey of radiotherapy facilities in December 2009. The required number of linear accelerators (R) was calculated from the projected cancer incidence figures for 2009 and was based on 1.6 linear accelerators being required per 1000 new cancer patients. The 'GAP' in Radiotherapy services (G) was R minus A. The maximum treatment capacity (MTC) was the ratio of A over R multiplied by 52.3%, assuming that all linear accelerators were operating at 100% capacity. As each linear accelerator can treat 331 new patients each year, the number of new cancer PNT is G x 331. The estimated 5-year survival benefit from radiotherapy is 16%, and the average survival for all patients receiving radiotherapy (radical and palliative) is 0.76 year. Hence, the number of PD attributed to the 'GAP' is PNT x 16%, and the YLL to cancer is PNT x 0.76. A literature search and local knowledge of health department Radiotherapy Plans in all jurisdictions were used to determine the action being taken to achieve a 52.3% treatment rate. RESULTS: In 2009, the 'GAP' was 50 linear accelerators in Australia and the MTC was 38%, the same as it was in 1999, but there has been an increase in PNT each year from 7419 in 1999 to 16,550 in 2009, and PD each year increased from 1187 in 1999 to 2649 in 2009, and YLL each year increased from 5638 in 1999 to 12,585 in 2009. In New Zealand in 2009, the 'GAP' was nine linear accelerators and the MTC was 38%. An estimated 3310 persons did not receive radiotherapy in 2009 in New Zealand, and as a result, there were 523 PD and 2266 YLL. The review showed that new and replacement machines were being installed in all jurisdictions in Australia and in New Zealand. Only Victoria and Queensland have a Radiotherapy Plan beyond 2010, but both have underestimated the projected cancer incidence. CONCLUSION: Urgent action is needed by health departments and governments on both sides of the Tasman to improve access and equity to this essential cancer treatment. There is merit in the Baume Report recommendation of establishing a national body to oversee radiotherapy services in all jurisdictions in Australia. A similar central body should also be considered for New Zealand.

Evaluation of inelastic hadronic processes for 250 MeV proton interactions in tissue and iron using GEANT4.

When high-energy protons interact in beam delivery systems and are stopped in patients, a fraction of beam will undergo nuclear interactions that release secondary particles, in particular, neutrons of different energies. The GEANT4 Monte Carlo Code was used to simulate the interaction of 250 MeV proton beam in tissue and iron to calculate the energy and angular distributions of generated protons, neutrons and photons, and thus provide H* (10), the ambient dose equivalent. A modular physics list by utilising electromagnetic interactions and hadronic interactions was constructed. Three different GEANT4 models that include the low-energy parameterisation, binary cascade and pre-compound model with Bertini cascade for proton inelastic interactions were compared. The findings suggest that the models play critical roles in terms of secondary particle generation. Further benchmarks are necessary to select the best model predicting a realistic scenario.