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Purpose: To analyze clinical results and quality of life of patients with localized prostate cancer after irradiation of the prostate with an 18F-choline-PET/CT-based simultaneous integrated boost (SIB) in comparison to a control group without SIB.Methods: A total of 134 patients underwent intensity-modulated radiotherapy from 2007-2010. All patients received a total dose of 76 Gy with 2 Gy fractions to the prostate; 67 patients received an additional SIB of 80 Gy. The median follow-up was 65 months. Quality of life was evaluated with the EPIC (Expanded Prostate Cancer Index Composite) questionnaire.Results: Baseline characteristics were similar in both groups (prostate-specific antigen 11 ng/ml vs. 8 ng/ml, p = 0.20, Gleason score <6 in 36% vs. 46%, p = 0.22, with vs. without SIB). No prostate cancer-related death was observed. No significant difference of quality of life scores was found. The largest difference after 5-6 years in comparison to baseline was reported for sexual bother (mean 15 vs. 17 points with vs. without SIB). Mean urinary scores did not decrease. Bowel bother scores changes were larger in the SIB group (mean 5 vs. 2 points, dependent on SIB volume), with increased bowel problems (15 vs. 2% big/moderate problem with bowel movements, p = 0.03). However, a trend towards higher efficacy with SIB resulted (biochemical recurrence-free survival of 92% vs. 85%, p = 0.17).Conclusions: The first long-term analysis of patients treated with SIB based on molecular imaging with 18-F-choline-PET/CT showed an excellent biochemical recurrence-free survival, but a larger percentage of bowel problems in comparison to the control group. [ABSTRACT FROM AUTHOR]

Introduction: Stereotactic body radiotherapy (SBRT) is an ablative method for lung malignancies. Here, the definition of the gross target volume (GTV) is subject to interobserver variation. In this study, we aimed to evaluate the interobserver variability during SBRT and its dosimetric impact, as well as to introduce a semi-automated delineation tool for both planning computer tomography (P-CT) and cone beam CT (CBCT) to help to standardise GTV delineation and adaptive volume-change registration., Methods: The interobserver variation of GTV manual contours from five physicians was analysed in 15 patients after lung SBRT on free breathing (FB) P-CT (n = 15) and CBCT (n = 90) before and after each fraction. The dosimetric impact from interobserver variations of GTV based on the original treatment plan was analysed. Next, the accuracy of an in-house easy-to-use semi-automated-segmentation algorithm for pulmonary lesions was compared with gold standard contours in FB P-CT and CBCT, as well as 4D P-CT of additional 10 patients., Results: The interobserver variability in manual contours resulted in violations of dose coverage of the planning target volume (PTV), which, in turn, resulted in compromised tumour control probability in contours from four physicians. The validation of the semi-automated delineation algorithm using thorax phantom led to a highly reliable accuracy in defining GTVs. Comparing the unsupervised auto-contours with the gold standard delineation revealed high equal high concordance for FB P-CT, 4D P-CT and CBCT, with a DSC of 0.83, 0.76 and 0.8, respectively. The supervised use of the semi-automated delineation tool improved its accuracy, with DSCs of 0.86, 0.86 and 0.8 for FB P-CT, 4D P-CT and CBCT, respectively. The use of the algorithm was associated with a significantly shorter working time. The semi-automated delineation tool can accurately register volume changes in CBCTs., Conclusion: The segmentation algorithm provides a reliable, standardised and time-saving alternative for manual delineation in lung SBRT in P-CT and CBCT., (© 2022 The Authors. Journal of Medical Radiation Sciences published by John Wiley & Sons Australia, Ltd on behalf of Australian Society of Medical Imaging and Radiation Therapy and New Zealand Institute of Medical Radiation Technology.)