Assessment of radiobiological metrics applied to patient-specific QA process of VMAT prostate treatments.

VMAT is a powerful technique to deliver hypofractionated prostate treatments. The lack of correlations between usual 2D pretreatment QA results and the clinical impact of possible mistakes has allowed the development of 3D verification systems. Dose determination on patient anatomy has provided clinical predictive capability to patient-specific QA process. Dose-volume metrics, as evaluation criteria, should be replaced or complemented by radiobiological indices. These metrics can be incorporated into individualized QA extracting the information for response parameters (gEUD, TCP, NTCP) from DVHs. The aim of this study is to assess the role of two 3D verification systems dealing with radiobiological metrics applied to a prostate VMAT QA program. Radiobiological calculations were performed for AAPM TG-166 test cases. Maximum differences were 9.3% for gEUD, -1.3% for TCP, and 5.3% for NTCP calculations. Gamma tests and DVH-based comparisons were carried out for both systems in order to assess their performance in 3D dose determination for prostate treatments (high-, intermediate-, and low-risk, as well as prostate bed patients). Mean gamma passing rates for all structures were bet-ter than 92.0% and 99.1% for both 2%/2 mm and 3%/3 mm criteria. Maximum discrepancies were (2.4% ± 0.8%) and (6.2% ± 1.3%) for targets and normal tis-sues, respectively. Values for gEUD, TCP, and NTCP were extracted from TPS and compared to the results obtained with the two systems. Three models were used for TCP calculations (Poisson, sigmoidal, and Niemierko) and two models for NTCP determinations (LKB and Niemierko). The maximum mean difference for gEUD calculations was (4.7% ± 1.3%); for TCP, the maximum discrepancy was (-2.4% ± 1.1%); and NTCP comparisons led to a maximum deviation of (1.5% ± 0.5%). The potential usefulness of biological metrics in patient-specific QA has been explored. Both systems have been successfully assessed as potential tools for evaluating the clinical outcome of a radiotherapy treatment in the scope of pretreatment QA.

PITASOR epidemiological study: prevalence, incidence and treatment of anaemia in radiation therapy oncology departments in Spain.

INTRODUCTION: Anemia is the most common haematological complication in cancer patients. OBJECTIVE: Analysis of the incidence, prevalence and treatment of anemia in oncologic patients treated in Radiation Oncology Departments in Spain (ROD) and monitoring of the existing recommendations for the treatment of anemia. MATERIAL AND METHODS: Observational, prospective, multicenter study which involved 19 Spanish ROD. The study was approved by the CEIC Central Defense Hospital. 477 patients with solid tumors, subsidiary of RT with radical intent referred to such centers within a period of one month (5/5/09 to 5/6/09) and gave their consent to participate in the study. We gathered the main characteristics of patients and their oncologic disease. All patients underwent a determination of Hb levels before RT, upon reaching 25-35 Gy and at the end treatment. In patients with anemia we assessed the existence of related symptoms and its treatment. RESULTS: Basal situation: The prevalence of anemia was 34.8% (166 patients). Mean Hb in patients with anemia was 11.17 ± 1.07 g/dl. Anemia-related symptoms were present in 34% of the patients. Anemia predisposing factors were: stage of the disease, previously received chemotherapy, and hormonal therapy. 39% (66 patients) received anemia treatment, with a mean Hb of 10.43 ± 1.04 g/dl. During RT: The prevalence of anemia was 38.9% (182 patients) with a mean Hb of 11.24 ± 1.21 g/dl. Predisposing factors for anemia during RT treatment were: age, male sex, chemotherapy prior to RT, basal anemia and chemotherapy during RT. 36.3% (66 patients) had anemia-related symptoms. 34.6% (63 patients) with a mean Hb of 10.5 ± 1.37 g/dl received treatment for anemia. The prevalence of anemia at the end of the RT was 38.1% (177 patients) with a mean Hb of 11.19 ± 1.18 g/dl. The predisposing factors for the appearance of anemia at the end of RT were: male sex, anemia at basal situation and during treatment and chemotherapy during RT. 34% (61 patients) had anemia-related symptoms and 73 patients (41.2%) with a mean Hb of 10.5 ± 1.22 g/dl received treatment for anemia. The presence of anemia-related symptoms was significantly correlated with the beginning of treatment for anemia. The incidence of anemia (new cases) during radiotherapy was 17.5%. CONCLUSION: The prevalence of anemia in basal situation, during RT and at the end of RT is 34.8%, 38.9% and 38.1%. During RT the incidence of anemia is 17.5%. 39.8%-41.2% of patients with anemia and 64.2%-68% of patients with anemia-related symptoms received treatment. Treatment of anemia starts with Hb<11 g/dl and the goal is to achieve Hb 12 g/dl. In our Radiotherapy Oncology Departments, the treatment of anemia complies with the current recommendations and guidelines in use.