The present study evaluates the performance of a newly released photon‐beam dose calculation algorithm that is incorporated into an established treatment planning system (TPS). We compared the analytical anisotropic algorithm (AAA) factory‐commissioned with “golden beam data” for Varian linear accelerators with measurements performed at two institutions using 6‐MV and 15‐MV beams. The TG‐53 evaluation regions and criteria were used to evaluate profiles measured in a water phantom for a wide variety of clinically relevant beam geometries. The total scatter factor (TSF) for each of these geometries was also measured and compared against the results from the AAA.At one institute, TLD measurements were performed at several points in the neck and thoracic regions of a Rando phantom; at the other institution, ion chamber measurements were performed in a CIRS inhomogeneous phantom. The phantoms were both imaged using computed tomography (CT), and the dose was calculated using the AAA at corresponding detector locations. Evaluation of measured relative dose profiles revealed that 97%, 99%, 97%, and 100% of points at one institute and 96%, 88%, 89%, and 100% of points at the other institution passed TG‐53 evaluation criteria in the outer beam, penumbra, inner beam, and buildup regions respectively. Poorer results in the inner beam regions at one institute are attributed to the mismatch of the measured profiles at shallow depths with the “golden beam data.”For validation of monitor unit (MU) calculations, the mean difference between measured and calculated TSFs was less than 0.5%; test cases involving physical wedges had, in general, differences of more than 1%. The mean difference between point measurements performed in inhomogeneous phantoms and Eclipse was 2.1% (5.3% maximum) and all differences were within TG‐53 guidelines of 7%. By intent, the methods and evaluation techniques were similar to those in a previous investigation involving another convolution–superposition photon‐beam dose calculation algorithm in another TPS, so that the current work permitted an independent comparison between the two algorithms for which results have been provided.PACS number: 87.53.Dq

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Recommendations by Canadian urologists and radiation oncologists for the treatment of clinically localized prostate cancer ORIGINAL RESEARCH Abstract Objective: Previous work has shown that urologists and radiation oncologists prefer the treatment that they themselves deliver when treating clinically localized prostate cancer. Our objective was to determine whether Canadian radiation oncologists and urologists have similar biases in favour of the treatments that they themselves deliver for localized prostate cancer. Methods:We developed a survey to poll the beliefs that Canadian radiation oncologists and urologists held toward prostate specific antigen (PSA) screening, survival benefits of treatment, recommendations for treatment of prostate cancer and the likelihood of side effects with each therapy. Results:Urologists were more likely to recommend routine PSA screening for men up to age 70 (p < 0.001), while radiation oncologists were more likely to recommend PSA screening for men over age 80 (p < 0.04). More urologists felt that there was "definitely" a survival advantage with radical prostatectomy (RP) (60% v. 21%, p < 0.001). More radiation oncologists recommend external beam radiation therapy (EBRT) (p < 0.01) or brachytherapy (p < 0.03) to treat low-risk prostate cancer. More urologists than radiation oncologists recommend RP for intermediate-risk patients (98% v. 70%, p < 0.001). Conclusion:Most Canadian urologists and radiation oncologists recommend routine PSA screening for men aged 50 to 70. A significant preference was detected among both urologists and radiation oncologists for the treatment that they themselves deliver. While both urologists and radiation oncologists recommend prostatectomy for the treatment of low-risk localized prostate cancer, urologists are significantly less likely to recommend EBRT. Conversely, when patients present with intermediate-risk prostate cancer, radiation oncologists were significantly less likely than urologists to recommend a prostatectomy.

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The authors find a small but nontrivial probability that breast cancer patients will be incorrectly staged and thus may be subjected to inappropriate treatment. Results are sensitive to a number of variables, and some routinely used tests for metastasis have very limited information value. This work has implications for the methods used in cancer staging, and the methods are generalizable for quantitative risk assessment of treatment errors.

In 2006, breast cancer is expected to continue as the leading form of cancer diagnosed in women, and the second leading cause of cancer mortality in this group. A method that has proven useful for guiding the choice of treatment strategy is the assessment of histological tumor grade. The grading is based upon the mitosis count, nuclear pleomorphism, and tubular formation, and is known to be subject to inter-observer variability. Since cancer grade is one of the most significant predictors of prognosis, errors in grading can affect patient management and outcome. Hence, there is a need to develop a breast cancer-grading tool that is minimally operator dependent to reduce variability associated with the current grading system, and thereby reduce uncertainty that may impact patient outcome. In this work, we explored the potential of a computer-based approach using fractal analysis as a quantitative measure of cancer grade for breast specimens. More specifically, we developed and optimized computational tools to compute the fractal dimension of low-versus high-grade breast sections and found them to be significantly different,These results indicate that fractal dimension (a measure of morphologic complexity) may be a useful tool for demarcating low-versus high-grade cancer specimens, and has potential as an objective measure of breast cancer grade. Such prognostic value could provide more sensitive and specific information that would reduce inter-observer variability by aiding the pathologist in grading cancers.

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