[18]F-fluoroethyl-l-tyrosine positron emission tomography for radiotherapy target delineation: Results from a Radiation Oncology credentialing program.

Background and purpose: The [18]F-fluoroethyl-l-tyrosine (FET) PET in Glioblastoma (FIG) study is an Australian prospective, multi-centre trial evaluating FET PET for newly diagnosed glioblastoma management. The Radiation Oncology credentialing program aimed to assess the feasibility in Radiation Oncologist (RO) derivation of standard-of-care target volumes (TVMR) and hybrid target volumes (TVMR+FET) incorporating pre-defined FET PET biological tumour volumes (BTVs). Materials and methods: Central review and analysis of TVMR and TVMR+FET was undertaken across three benchmarking cases. BTVs were pre-defined by a sole nuclear medicine expert. Intraclass correlation coefficient (ICC) confidence intervals (CIs) evaluated volume agreement. RO contour spatial and boundary agreement were evaluated (Dice similarity coefficient [DSC], Jaccard index [JAC], overlap volume [OV], Hausdorff distance [HD] and mean absolute surface distance [MASD]). Dose plan generation (one case per site) was assessed. Results: Data from 19 ROs across 10 trial sites (54 initial submissions, 8 resubmissions requested, 4 conditional passes) was assessed with an initial pass rate of 77.8 %; all resubmissions passed. TVMR+FET were significantly larger than TVMR (p < 0.001) for all cases. RO gross tumour volume (GTV) agreement was moderate-to-excellent for GTVMR (ICC = 0.910; 95 % CI, 0.708-0.997) and good-to-excellent for GTVMR+FET (ICC = 0.965; 95 % CI, 0.871-0.999). GTVMR+FET showed greater spatial overlap and boundary agreement compared to GTVMR. For the clinical target volume (CTV), CTVMR+FET showed lower average boundary agreement versus CTVMR (MASD: 1.73 mm vs. 1.61 mm, p = 0.042). All sites passed the planning exercise. Conclusions: The credentialing program demonstrated feasibility in successful credentialing of 19 ROs across 10 sites, increasing national expertise in TVMR+FET delineation.

Multi-observer contouring of male pelvic anatomy: Highly variable agreement across conventional and emerging structures of interest.

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 ± 0.05; 0.88 ± 0.05; 0.93 ± 0.03; 0.81 ± 0.07; 0.80 ± 0.06, respectively). Seminal vesicle contours were more variable (ICC = 0.75, DSC = 0.73 ± 0.14), while colon and bowel bag contoured volumes were consistent (ICC = 0.97; 0.97), but displayed poor overlap (DSC = 0.58 ± 0.22; 0.67 ± 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 ± 0.22; 0.41 ± 0.21; 0.66 ± 0.21; 0.16 ± 0.17; 0.15 ± 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.

Publication rates of abstracts presented at the Royal Australian and New Zealand College of Radiologists annual scientific meetings: Any change since 2004?

INTRODUCTION: The aim of this study was to determine the publication rate of abstracts presented at annual Royal Australian and New Zealand College of Radiologists (RANZCR) conferences. METHODS: The College's Annual Scientific Meetings (ASMs) from 2010 to 2013 were examined, with the goal of comparing these results to the findings of an earlier identical study that examined RANZCR ASMs from 1996 to 1999. RESULTS: Of the 1152 research abstracts presented, 468 (41%) had been published as full articles. The overall abstract to publication ratio (APR) for radiology was 34% and for radiation oncology was 57%. For oral presentations, these were 44% for radiology and 55% for radiation oncology. Papers were published in a wide variety of journals but 23% of articles appeared in the College's journal, the Journal of Medical Imaging and Radiation Oncology. The mean time between presentation and publication was 16.5 months (median 17 months). CONCLUSION: Publication rates are comparable with international reports. The APR has increased since the previous study for both disciplines, but more so for Radiation Oncology.

Treatment of brain oligometastases with hypofractionated stereotactic radiotherapy utilising volumetric modulated arc therapy.

Stereotactic radiosurgery (SRS) is commonly used to treat brain metastases, particularly in the oligometastatic setting. This study analyses our initial experience in treating oligometastatic brain disease using Volumetric Modulated Arc Therapy (VMAT) to deliver hypofractionated stereotactic radiotherapy (HFSRT). Sixty-one patients were treated with HFSRT with a median dose of 24 Gy (range 22-40 Gy) in a median of three fractions (range 2-10 fractions). With a median follow-up of 23 months, the local control rate was 74 % for the entire cohort. Local control was 87 % for patients who had surgery with no radiological evidence of residual disease followed by HFSRT compared with 69 % in patients treated with HFSRT alone. The overall median time post radiotherapy to local failure was 8.6 months and to extracranial failure was 7.9 months. The mean time to distant brain failure was 9.9 months. Twenty-two patients (36 %) died during the study with median time to death of 4.4 months. Median overall survival (OS) from treatment was 21 months and 12 month OS was 60 %. Our experience with HFSRT using VMAT for oligometastatic brain metastases in the post-operative setting demonstrates comparable local control and survival rates compared with international published data. In the intact brain metastasis setting, local control using the dose levels and delivery in this cohort may be inferior to radio-surgical series. Local control is independent of histology. Careful selection of patients remains critical.

Neurotropic melanoma: the management of localised disease.

Neurotropic melanoma is a rare subtype of cutaneous malignant melanoma. Compared with conventional melanoma, it is more locally aggressive with an increased tendency for local recurrence but less likely for nodal or distant metastases. These tumours can be a diagnostic dilemma with a variety of morphological, histopathological, and immunophenotypical expressions. The often amelanotic, benign appearance may lead to treatment issues such as late presentation, diagnostic delay, misdiagnosis, insufficient surgical margins, and recurrence with resulting poor outcome. The neurotropic nature of the disease and prevalence in the head and neck region can result in perineural and neural invasion along named large nerves into the brain with resulting neuropathies. Wide local excision with adjuvant radiotherapy where indicated remains the current practice for treatment with chemotherapy predominately being reserved as a salvage treatment for patients with disseminated disease.