This work describes the dosimetric commissioning of the treatment planning system (TPS) RayStation v6.1 from RaySearch Laboratories (Stockholm, Sweden) for a synchrotron-based scanned proton beam ...delivery with isocentric and non-isocentric setups at MedAustron. Focus was on the comparison of the pencil beam (PBv4.1) and Monte Carlo (MCv4.0) calculation algorithms. Commissioning of dose calculations was done first for 1D/2D dose delivery where the performance of the beam model in reproducing dosimetric properties for the delivery of single static pencil beams and mono-energetic layers with multiple spots was evaluated. The commissioning for 3D beam delivery employed test cases with increasing complexity: from box-shaped fields in homogeneous phantoms to the introduction of oblique incidences and inhomogeneities. Dose calculations were compared to the measured data for different air gaps and using beams with and without range shifter (RaShi). Depth-dose curves and spot shape comparisons showed good agreement of the results obtained with PBv4.1 and MCv4.0 algorithms at isocentric setup for open beam configurations (without RaShi). Comparison of transverse dose profiles for lateral heterogeneities at different depths showed better performance of the MCv4.0 algorithm in comparison to the PBv4.1 algorithm. In the case of 3D delivery comparisons of measured and TPS-calculated dose with MCv4.0 algorithm in box-shaped fields in water showed an average agreement within 2%. The results for dose calculations with the PBv4.1 algorithm showed larger deviations for beams with RaShi at all evaluated air gaps (from 64.8 cm to 14.8 cm). Our results suggest that the MCv4.0 algorithm shall be used in clinics for final dose calculation when beams with RaShi are used especially in the presence of large air gaps, inclined patient surface and lateral inhomogeneities. The detailed stepwise methodology implemented for the RayStation commissioning in this work could serve as further guidance for other facilities introducing a new TPS for proton beam therapy.
Vertebral fracture is one of the major adverse clinical consequences of osteoporosis; however, there are few data concerning the incidence of vertebral fracture in population samples of men and ...women. The aim of this study was to determine the incidence of vertebral fracture in European men and women. A total of 14,011 men and women aged 50 years and over were recruited from population‐based registers in 29 European centers and had an interviewer‐administered questionnaire and lateral spinal radiographs performed. The response rate for participation in the study was approximately 50%. Repeat spinal radiographs were performed a mean of 3.8 years following the baseline film. All films were evaluated morphometrically. The definition of a morphometric fracture was a vertebra in which there was evidence of a 20% (+4 mm) or more reduction in anterior, middle, or posterior vertebral height between films—plus the additional requirement that a vertebra satisfy criteria for a prevalent deformity (using the McCloskey‐Kanis method) in the follow‐up film. There were 3174 men, mean age 63.1 years, and 3614 women, mean age 62.2 years, with paired duplicate spinal radiographs (48% of those originally recruited to the baseline survey). The age standardized incidence of morphometric fracture was 10.7/1000 person years (pyr) in women and 5.7/1000 pyr in men. The age‐standardized incidence of vertebral fracture as assessed qualitatively by the radiologist was broadly similar—12.1/1000 pyr and 6.8/1000 pyr, respectively. The incidence increased markedly with age in both men and women. There was some evidence of geographic variation in fracture occurrence; rates were higher in Sweden than elsewhere in Europe. This is the first large population‐based study to ascertain the incidence of vertebral fracture in men and women over 50 years of age across Europe. The data confirm the frequent occurrence of the disorder in men as well as in women and the rise in incidence with age.
Purpose: To evaluate treatment plan quality of IMRT and VMAT plans for high energy photon beams delivered with (FF) and without (FFF) flattening filter. Methods: 9‐field IMRT and 360° single arc VMAT ...plans, based on 10 MV beams with and without flattening filter, were created using Monaco (Elekta/CMS, v.2.04, USA) for three different patients (prescribed PTV dose 78 Gy). This treatment planning systems was commissioned for FF and FFF beams provided by an Elekta linac. The Pareto optimal fronts were created by calculating different treatment plans with varying rectum constraints and evaluating the PTV volume receiving less than 95% of the prescribed dose (V <95%) and the volume of the rectum receiving 70Gy or more (V 70Gy). Treatment plan efficiency was evaluated by recording number of monitor units (MUs) and by measuring the delivery time (T) using an Elekta Precise linear accelerator in FF and FFF mode. Results: The POFs of the rectum for both IMRT and VMAT in FFF mode were similar or even superior to the FF‐ modalities. For two of the three patients the POFs of IMRT and VMAT revealed a systematic difference of about 2% in target coverage. The POFs of the remaining patient showed virtually no difference for all four modalities. The delivery time of IMRT FFF decreased by about 23% compared to IMRT FF. In contrast to the IMRT techniques, delivery time increased by 20% when using VMAT FFF compared to VMAT FF. Conclusions: The evaluation of the POFs confirms that a flattening filter is not necessary for static and rotational IMRT treatments. Similar studies are needed for other IMRT indications, like head‐and‐neck cancer, to draw final conclusions. Sequencing algorithms for FFF‐beams need to be optimized and further improvement of the mechanical MLC properties are desirable for VMAT in FFF mode. Corporate sponsored research by Elekta
Vertebral fractures are associated with back pain and disability. There are, however, few prospective data looking at back pain and disability following identification of radiographic vertebral ...fracture. The aim of this analysis was to determine the impact of radiographically identified vertebral fracture on the subsequent occurrence of back pain and disability. Women aged 50 years and over were recruited from population registers in 18 European centers for participation in the European Prospective Osteoporosis Study. Participants completed an interviewer-administered questionnaire which included questions about back pain in the past year and various activities of daily living, and they had lateral spine radiographs performed. Participants in these centers were followed prospectively and had repeat spine radiographs performed a mean of 3.7 years later. In addition they completed a questionnaire with the same baseline questions concerning back pain and activities of daily living. The presence of prevalent and incident vertebral fracture was defined using established morphometric criteria. The data were analyzed using logistic regression with back pain or disability (present or absent) at follow-up as the outcome variable with adjustment made for the baseline value of the variable. The study included 2,260 women, mean age 62.2 years. The mean time between baseline and follow-up survey was 5.0 years. Two hundred and forty participants had prevalent fractures at the baseline survey, and 85 developed incident fractures during follow-up. After adjustment for age, center, and the baseline level of disability, compared with those without baseline prevalent fracture, those with a prevalent fracture (odds ratio OR = 1.4; 95% confidence interval CI 1.0 to 2.0) or an incident fracture (OR = 1.7; 95% CI, 0.9 to 3.2) were more likely to report disability at follow-up, though the confidence intervals embraced unity. Those with both a prevalent and incident fracture, however, were significantly more likely to report disability at follow-up (OR = 3.1; 95% CI, 1.4 to 7.0). After adjustment for age, center, and frequency of back pain at baseline, compared with those without baseline vertebral fracture, those with a prevalent fracture were no more likely to report back pain at follow-up (OR = 1.2; 95% CI, 0.8 to 1.7). There was a small increased risk among those with a preexisting fracture who had sustained an incident fracture during follow-up (OR = 1.6; 95% CI, 0.6 to 4.1) though the confidence intervals embraced unity. In conclusion, although there was no significant increase in the level of back pain an average of 5 years following identification of radiographic vertebral fracture, women who suffered a further fracture during follow-up experienced substantial levels of disability with impairment in key physical functions of independent living.
The aim of this analysis was to determine the influence of lifestyle, anthropometric and reproductive factors on the subsequent risk of incident vertebral fracture in men and women aged 50-79 years. ...Subjects were recruited from population registers from 28 centers across Europe. At baseline, they completed an interviewer-administered questionnaire and had lateral thoraco-lumbar spine radiographs performed. Repeat spinal radiographs were performed a mean of 3.8 years later. Incident vertebral fractures were defined morphometrically and also qualitatively by an experienced radiologist. Poisson regression was used to determine the influence of the baseline risk factor variables on the occurrence of incident vertebral fracture. A total of 3173 men (mean age 63.1 years) and 3402 women (mean age 62.2 years) contributed data to the analysis. In total there were 193 incident morphometric and 224 qualitative fractures. In women, an age at menarche 16 years or older was associated with an increased risk of vertebral fracture (RR = 1.80; 95%CI 1.24, 2.63), whilst use of hormonal replacement was protective (RR = 0.58; 95%CI 0.34, 0.99). None of the lifestyle factors studied including smoking, alcohol intake, physical activity or milk consumption showed any consistent associations with incident vertebral fracture. In men and women, increasing body weight and body mass index were associated with a reduced risk of vertebral fracture though, apart from body mass index in men, the confidence intervals embraced unity. For most variables the strengths of the associations observed were similar using the qualitative and morphometric approaches to fracture definition. In conclusion our data suggest that modification of other lifestyle risk factors is unlikely to have a major impact on the population occurrence of vertebral fractures. The important biological mechanisms underlying vertebral fracture risk need to be explored using new investigational strategies.
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