61 research outputs found

    Do patients’ information needs decrease over the course of radiotherapy?

    Get PDF
    PURPOSE: We aimed to investigate if cancer patients’ information needs decrease during radiotherapy and if so, which patient, consultation and radiation oncologist characteristics are associated with a decrease in information needs over time. METHODS: In this longitudinal study, patients (n = 104) completed a baseline questionnaire a week before the initial radiotherapy consultation, immediately following this initial consultation, and 1 week prior to the first follow-up visit, which took place on average 3–5 weeks after the initial visit. Besides information needs, measured by the Information Preference for Radiotherapy Patients scale, the questionnaire assessed patient, consultation and radiation oncologist characteristics. RESULTS: Information needs decreased over time, but remained at a high level. Being religious, being male, having low health literacy and higher perceived involvement during the consultation were all statistically significantly associated to a decrease in information needs on specific domains (e.g. procedures or side effects). CONCLUSIONS: Cancer patients’ information needs decline between the initial consultation and the first follow-up visit, but remain high. It is therefore advised to investigate the patients’ information needs at every radiotherapy visit and not rely on giving information just once. Furthermore, radiation oncologists should check if the information given at first consultation is understood and remembered. By those means, tailored information giving becomes possible

    Independent position correction on tumor and lymph nodes; consequences for bladder cancer irradiation with two combined IMRT plans

    Get PDF
    Abstract Background The application of lipiodol injections as markers around bladder tumors combined with the use of CBCT for image guidance enables daily on-line position correction based on the position of the bladder tumor. However, this might introduce the risk of underdosing the pelvic lymph nodes. In this study several correction strategies were compared. Methods For this study set-up errors and tumor displacements for ten complete treatments were generated; both were based on the data of 10 bladder cancer patients. Besides, two IMRT plans were made for 20 patients, one for the elective field and a boost plan for the tumor. For each patient 10 complete treatments were simulated. For each treatment the dose was calculated without position correction (option 1), correction on bony anatomy (option 2), on tumor only (option 3) and separately on bone for the elective field (option 4). For each method we analyzed the D99% for the tumor, bladder and lymph nodes and the V95% for the small intestines, rectum, healthy part of the bladder and femoral heads. Results CTV coverage was significantly lower with options 1 and 2. With option 3 the tumor coverage was not significantly different from the treatment plan. The ΔD99% (D99%, option n - D99%, treatment plan) for option 4 was small, but significant. For the lymph nodes the results from option 1 differed not significantly from the treatment plan. The median ΔD99% of the other options were small, but significant. ΔD99% for PTVbladder was small for options 1, 2 and 4, but decreased up to -8.5 Gy when option 3 was applied. Option 4 is the only method where the difference with the treatment plan never exceeds 2 Gy. The V95% for the rectum, femoral heads and small intestines was small in the treatment plan and this remained so after applying the correction options, indicating that no additional hot spots occurred. Conclusions Applying independent position correction on bone for the elective field and on tumor for the boost separately gives on average the best target coverage, without introducing additional hot spots in the healthy tissue.</p

    The effect of on-line position correction on the dose distribution in focal radiotherapy for bladder cancer

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>The purpose of this study was to determine the dosimetric effect of on-line position correction for bladder tumor irradiation and to find methods to predict and handle this effect.</p> <p>Methods</p> <p>For 25 patients with unifocal bladder cancer intensity modulated radiotherapy (IMRT) with 5 beams was planned. The requirement for each plan was that 99% of the target volume received 95% of the prescribed dose. Tumor displacements from -2.0 cm to 2.0 cm in each dimension were simulated, using 0.5 cm increments, resulting in 729 simulations per patient. We assumed that on-line correction for the tumor was applied perfectly. We determined the correlation between the change in D<sub>99% </sub>and the change in path length, which is defined here as the distance from the skin to the isocenter for each beam. In addition the margin needed to avoid underdosage was determined and the probability that an underdosage occurs in a real treatment was calculated.</p> <p>Results</p> <p>Adjustments for tumor displacement with perfect on-line position correction resulted in an altered dose distribution. The altered fraction dose to the target varied from 91.9% to 100.4% of the prescribed dose. The mean D<sub>99% </sub>(± SD) was 95.8% ± 1.0%. There was a modest linear correlation between the difference in D<sub>99% </sub>and the change in path length of the beams after correction (R<sup>2 </sup>= 0.590). The median probability that a systematic underdosage occurs in a real treatment was 0.23% (range: 0 - 24.5%). A margin of 2 mm reduced that probability to < 0.001% in all patients.</p> <p>Conclusion</p> <p>On-line position correction does result in an altered target coverage, due to changes in average path length after position correction. An extra margin can be added to prevent underdosage.</p

    Grain Surface Models and Data for Astrochemistry

    Get PDF
    AbstractThe cross-disciplinary field of astrochemistry exists to understand the formation, destruction, and survival of molecules in astrophysical environments. Molecules in space are synthesized via a large variety of gas-phase reactions, and reactions on dust-grain surfaces, where the surface acts as a catalyst. A broad consensus has been reached in the astrochemistry community on how to suitably treat gas-phase processes in models, and also on how to present the necessary reaction data in databases; however, no such consensus has yet been reached for grain-surface processes. A team of ∼25 experts covering observational, laboratory and theoretical (astro)chemistry met in summer of 2014 at the Lorentz Center in Leiden with the aim to provide solutions for this problem and to review the current state-of-the-art of grain surface models, both in terms of technical implementation into models as well as the most up-to-date information available from experiments and chemical computations. This review builds on the results of this workshop and gives an outlook for future directions

    Accelerated high-dose radiotherapy alone or combined with either concomitant or sequential chemotherapy; treatments of choice in patients with Non-Small Cell Lung Cancer

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Results of high-dose chemo-radiotherapy (CRT), using the treatment schedules of EORTC study 08972/22973 or radiotherapy (RT) alone were analyzed among all patients (pts) with Non Small Cell Lung Cancer (NSCLC) treated with curative intent in our department from 1995–2004.</p> <p>Material</p> <p>Included are 131 pts with medically inoperable or with irresectable NSCLC (TNM stage I:15 pts, IIB:15 pts, IIIA:57 pts, IIIB:43 pts, X:1 pt).</p> <p>Treatment</p> <p>Group I: Concomitant CRT: 66 Gy/2.75 Gy/24 fractions (fx)/33 days combined with daily administration of cisplatin 6 mg/m<sup>2</sup>: 56 pts (standard).</p> <p>Group II: Sequential CRT: two courses of a 21-day schedule of chemotherapy (gemcitabin 1250 mg/m<sup>2 </sup>d1, cisplatin 75 mg/m2 d2) followed by 66 Gy/2.75 Gy/24 fx/33 days without daily cisplatin: 26 pts.</p> <p>Group III: RT: 66 Gy/2.75 Gy/24 fx/33 days or 60 Gy/3 Gy/20 fx/26 days: 49 pts.</p> <p>Results</p> <p>The 1, 2, and 5 year actuarial overall survival (OS) were 46%, 24%, and 15%, respectively.</p> <p>At multivariate analysis the only factor with a significantly positive influence on OS was treatment with chemo-radiation (P = 0.024) (1-, 2-, and 5-yr OS 56%, 30% and 22% respectively). The incidence of local recurrence was 36%, the incidence of distant metastases 46%.</p> <p>Late complications grade 3 were seen in 21 pts and grade 4 in 4 patients. One patient had a lethal complication (oesophageal). For 32 patients insufficient data were available to assess late complications.</p> <p>Conclusion</p> <p>In this study we were able to reproduce the results of EORTC trial 08972/22973 in a non-selected patient population outside of the setting of a randomised trial. Radiotherapy (66 Gy/24 fx/33 days) combined with either concomitant daily low dose cisplatin or with two neo-adjuvant courses of gemcitabin and cisplatin are effective treatments for patients with locally advanced Non-Small Cell Lung Cancer. The concomitant schedule is also suitable for elderly people with co-morbidity.</p

    Identifying Where REDD+ Financially Out Competes Oil Palm in Floodplain Landscapes Using a Fine-Scale Approach

    Get PDF
    Reducing Emissions from Deforestation and forest Degradation (REDD+) aims to avoid forest conversion to alternative land-uses through financial incentives. Oil-palm has high opportunity costs, which according to current literature questions the financial competitiveness of REDD+ in tropical lowlands. To understand this more, we undertook regional finescale and coarse-scale analyses (through carbon mapping and economic modelling) to assess the financial viability of REDD+ in safeguarding unprotected forest (30,173 ha) in the Lower Kinabatangan floodplain in Malaysian Borneo. Results estimate 4.7 million metric tons of carbon (MgC) in unprotected forest, with 64% allocated for oil-palm cultivations. Through fine-scale mapping and carbon accounting, we demonstrated that REDD+ can outcompete oil-palm in regions with low suitability, with low carbon prices and low carbon stock. In areas with medium oil-palm suitability, REDD+ could outcompete oil palm in areas with: very high carbon and lower carbon price; medium carbon price and average carbon stock; or, low carbon stock and high carbon price. Areas with high oil palm suitability, REDD + could only outcompete with higher carbon price and higher carbon stock. In the coarse-scale model, oil-palm outcompeted REDD+ in all cases. For the fine-scale models at the landscape level, low carbon offset prices (US 3MgCO2e)wouldenableREDD+tooutcompeteoilpalmin553 MgCO2e) would enable REDD+ to outcompete oil-palm in 55% of the unprotected forests requiring US 27 million to secure these areas for 25 years. Higher carbon offset price (US 30MgCO2e)wouldincreasethecompetitivenessofREDD+withinthelandscapebutwouldstillonlycapturebetween6930 MgCO2e) would increase the competitiveness of REDD+ within the landscape but would still only capture between 69%-74% of the unprotected forest, requiring US 380–416 million in carbon financing. REDD+ has been identified as a strategy to mitigate climate change by many countries (including Malaysia). Although REDD+ in certain scenarios cannot outcompete oil palm, this research contributes to the global REDD+ debate by: highlighting REDD+ competitiveness in tropical floodplain landscapes; and, providing a robust approach for identifying and targeting limited REDD+ funds

    Blaassparende behandelingen bij blaaskanker: mogelijkheden en ontwikkelingen in de radiotherapie

    No full text
    The standard treatment for muscle-invasive bladder cancer is surgical removal of the bladder and construction of a neobladder. Recently, important improvements have been made in the potential for bladder-conserving treatment using radiotherapy. External beam radiotherapy has undergone technological improvements, as a result of which it is possible to radiate the tumour more precisely while decreasing radiation to healthy tissue. Radiochemotherapy improves local recurrence-free and overall survival compared with radiotherapy alone. The results of this combined treatment are comparable with those of surgery. Additionally, Dutch radiotherapy departments have collected data in a national database of 1040 selected patients with confined bladder cancer. These patients were treated with external beam radiation, limited surgery and brachytherapy. The 5-year local recurrence-free survival was 75%. Bladder conserving treatment options for muscle-invasive bladder cancer should be discussed during the multidisciplinary meetin

    Comparison of three radiotherapy modalities on biochemical control and overall survival for the treatment of prostate cancer: A systematic review

    No full text
    Background and Purpose: For the radiation treatment of prostate cancer high dose should be delivered for optimal biochemical control. Treatment can be given by dose-escalated external beam radiotherapy (EBRT) or external beam radiotherapy combined with a radioactive seed implantation (EBSeeds) or high-dose rate (HDR) brachytherapy (EBTI). Differences in outcome between the modalities were assessed by a systematic review. Materials and methods: A systematic search was performed resulting in 40 articles to be used. Data were extracted on biochemical control and overall survival at 3, 5, and 8 years and other time points mentioned in the articles. Also known prognostic parameters were noted. Comparison of the modalities was done by a Weibull survival analysis and estimation of Hazard Ratio's (HR) was done with 95% confidence intervals (95% CIs). Results: The HR for biochemical recurrence was 1.40 (95% CI 1.31-1.51) for EBRT relative to EBTI, and was 1.37 (95% CI 1.26-1.49) for EBSeeds relative to EBTI. The HR for overall survival was 1.50 (95% CI 1.29-1.73) for EBRT relative to EBTI, and was 2.33 (95% CI 2.04-2.66) for EBSeeds relative to EBTI. Conclusion: The combination of external beam radiotherapy and HDR brachytherapy results in a superior biochemical control and overall survival found in a systematic review on radiotherapy for prostate cancer. (C) 2009 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 93 (2009) 168-17

    Effectiveness and toxicity of single-fraction radiotherapy with 1 X 8 Gy for metastatic spinal cord compression

    No full text
    Toxicity and functional. outcome were evaluated in 199 MSCC-patients irradiated with 1 X 8 Gy. Motor function improved in 54/199 patients (27%). Patients who regained walking ability were 20/78 (26%). Long-term-survivors (>= 12 months) who needed re-irradiation for in-field-recurrence were 19/65 (29%). Acute toxicity was mild, late toxicity not observed. A randomised trial comparing single-fraction RT to multi-fraction RT is mandatory. (c) 2005 Elsevier Ireland Ltd. All rights reserve
    corecore