Introduction: This study quantified inter-observer contouring variations for multiple male pelvic structures, many of which are of emerging relevance for prostate cancer radiotherapy progression and toxicity response studies. Methods: Five prostate cancer patient datasets (CT and T2-weighted MR) were distributed to 13 observers for contouring. CT structures contoured included the clinical target volume (CTV), seminal vesicles, rectum, colon, bowel bag, bladder and peri-rectal space (PRS). MR contours included CTV, trigone, membranous urethra, penile bulb, neurovascular bundle and multiple pelvic floor muscles. Contouring variations were assessed using the intraclass correlation coefficient (ICC), Dice similarity coefficient (DSC), and multiple additional metrics. Results: Clinical target volume (CT and MR), bladder, rectum and PRS contours showed excellent inter-observer agreement (median ICC = 0.97; 0.99; 1.00; 0.95; 0.90, DSC = 0.83 AE 0.05; 0.88 AE 0.05; 0.93 AE 0.03; 0.81 AE 0.07; 0.80 AE 0.06, respectively). Seminal vesicle contours were more variable (ICC = 0.75, DSC = 0.73 AE 0.14), while colon and bowel bag contoured volumes were consistent (ICC = 0.97; 0.97), but displayed poor overlap (DSC = 0.58 AE 0.22; 0.67 AE 0.21). Smaller MR structures showed significant inter-observer variations, with poor overlap for trigone, membranous urethra, penile bulb, and left and right neurovascular bundles (DSC = 0.44 AE 0.22; 0.41 AE 0.21; 0.66 AE 0.21; 0.16 AE 0.17; 0.15 AE 0.15). Pelvic floor muscles recorded moderate to strong inter-observer agreement (ICC = 0.50-0.97), although large outlier variations were observed. Conclusions: Inter-observer contouring variation was significant for multiple pelvic structures contoured on MR.
Dose escalation in prostate cancer radiotherapy has been shown to improve biochemical control in all risk groups. 1 It is estimated that doses as high as 86.5 to 95.5 Gy are required to achieve prostate cancer ablation. 2 Such dose escalation must be balanced against the potential of increased gastrointestinal and genitourinary toxicity.
Introduction
The magnetic resonance linear accelerator (MRL) offers improved soft tissue visualization to guide daily adaptive radiotherapy treatment. This manuscript aims to report initial experience using a 1.5 T MRL in the first 6 months of operation, including training, workflows, timings and dosimetric accuracy.
Methods
All staff received training in MRI safety and MRL workflows. Initial sites chosen for treatment were stereotactic and hypofractionated prostate, thoraco‐abdomino‐pelvic metastasis, prostate bed and bladder. The Adapt To Shape (ATS) workflow was chosen to be the focus of treatment as it is the most robust solution for daily adaptive radiotherapy. A workflow was created addressing patient suitability, simulation, planning, treatment and peer review. Treatment times were recorded breaking down into the various stages of treatment.
Results
A total of 37 patients were treated and 317 fractions delivered (of which 313 were delivered using an ATS workflow) in our initial 6 months. Average treatment times over the entire period were 50 and 38 min for stereotactic and non‐stereotactic treatments respectively. Average treatment times reduced each month. The average difference between reference planned and ionization chamber measured dose was 0.0 ± 1.4%.
Conclusion
The MRL was successfully established in an Australian setting. A focus on training and creating a detailed workflow from patient selection, review and treatment are paramount to establishing new treatment programmes.
CD39 and CD73 are ecto-nucleotidases present on human peripheral blood mononuclear cells (PBMCs) and are emerging biomarkers on these cells in various disorders including cancer. Many factors influence PBMC quality, so it is essential to validate sample processing methods prior to incorporation in clinical studies. This study examined the impact of both PBMC cryopreservation and PBMC isolation using SepMate density gradient centrifugation on CD39 and CD73 expressing subsets. First, PBMCs were isolated from the peripheral blood of 11 healthy donors by routine Ficoll-Paque density gradient centrifugation, cryopreserved and compared with freshly isolated PBMCs by flow cytometry. The proportions of T and B cells expressing combinations of CD39 and CD73 were relatively stable over 6-month cryopreservation, although some T cell combinations revealed small but significant changes. Second, peripheral blood was collected from six healthy donors to compare PBMCs isolated by SepMate or Ficoll-Paque density gradient centrifugation. Compared with Ficoll-Paque, the more rapid SepMate method yielded 9.1% less PBMCs but did not alter cell viability or proportions of T and B cells expressing combinations of CD39 and CD73. The present study reveals that cryopreservation is suitable for studying T and B cells expressing combinations of CD39 and CD73. However, caution should be exercised when observing small differences in these cryopreserved subsets between different cohorts. Further, SepMate and Ficoll-Paque methods of PBMC isolation show similar results for T and B cell subset analysis; however, SepMate is a faster and easier approach.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.