During the French national course of radiotherapy, delineation stations were at disposition for the residents. A comparative study of delineation and doses prescribed for a clinical case of lung carcinoma is reported before and after the completion of a theoretical education.
For this comparative study, 120 residents divided in 30 groups, have delineated the case before and after a lecture of radio-anatomy and a presentation of volumes and doses. The software Artiview (Aquilab SAS) was used to calculate the volume ratio (VR), common volume (CV), additional volume (AV), kappa (K) and overlap (OV) between the different volumes of interest. The expansion margins and the prescribed doses were noticed. A comparative study by a test of Student for paired series was performed.
The GTV was 89.1cm(3) for the expert. It was 103.4 cm(3) (59.9-215.2 cm(3)) before versus 99.5 cm(3) (39.7-202.3 cm(3)) after the teaching intervention for participants. For GTV, comparison index were respectively before and after the intervention 1.16 cm(3) (0.7-2.4 cm(3)) and 1.1 cm(3)(0.5-2.3 cm(3)) for the VR (p=0.53), 78.4 cm(3) (58.9-91.8 cm(3)) and 76.4 cm(3) (40.2-92.1cm(3)) for the CV (p=0.27), 28.8 cm(3) (7.1-62 cm(3)) and 27.8 cm(3) (9.1-59.6 cm(3)) for the AV (p=0.7). OV and K were respectively 0.58 and 0.73 cm(3) before and after education. The median margin prescribed to obtain CTV from GTV was 6mm (5-10mm), no change was noticed after the course. The expert prescribed a 6mm margin. The median margin prescribed by the participants to obtain PTV from CTV was 7 mm (3-15 mm) before the course and 5mm (3-15 mm) afterwards, versus 5mm for the expert. The dose prescribed by the expert was 66 Gy on PTV. The dose was 66.2 Gy (60-70 Gy) before and 66.5 Gy (64-70 Gy) after course for residents.
No significant volume modification was found after the educational course. We noticed however an adaptation of the margins and a tendency to increase the prescribed dose as well as a reduction of the delineated volume. Good quality of the initial delineation could explain the absence of significant progress after education.
[Show abstract][Hide abstract] ABSTRACT: As part of French residents' radiotherapy training, delineation workstations were available at a national teaching course. We report a prospective comparative study of a non small cell lung cancer (NSCLC) case delineated by 120 residents before and after a radioanatomy/radiotherapy lecture.
The case of a patient with right upper lobe non small cell lung cancer (NSCLC) was provided for delineation to 32 groups of residents before and after a radiation therapy lecture about thoracic delineation. GTV, CTV and PTV was asked to each group. In a second step, the GTV, CTV and PTV were compared with those of 9 groups of senior physicians. Finally the consequences for treatment planning between each group before and after the course were explored.
The expert's average GTV, CTV and PTV were 89.1 cm3, 242.3 cm3 and 293.9 cm3 respectively. For residents, those volumes were 103.4 cm3, 242.3 cm3 and 457.9 cm3 before teaching, compared to 99.5 cm3, 224.2 cm3 and 412.5 cm3 after teaching. The overlap (OV) and kappa (KI) indices before and after education were respectively 0.58 and 0.73. Compared to senior physicians, OV and KI indices were lower in the residents group (p = 0.039 and p = 0.043). An increased dose to the lung is noted for the residents' dosimetry compared to the experts' (V20: 23.2% versus 36.5%) due to the larger PTV delineated. No significant difference was observed for other organs at risk.
There were no significant differences for the delineation of the GTV and CTV before and after the course, although the differences tended to decrease after the course. The good initial quality of the contours could explain the lack of difference. V20 for lung was higher in the residents group compared to the experts group (23.2% vs 36.5%). No other treatment planning consequences were observed for other critical organs.
[Show abstract][Hide abstract] ABSTRACT: To evaluate inter- and intra-observer variability in gross tumor volume definition for adult limb/trunk soft tissue sarcomas.
Imaging studies of 15 patients previously treated with preoperative radiation were used in this study. Five physicians (radiation oncologists, orthopedic surgeons and a musculoskeletal radiologist) were asked to contour each of the 15 tumors on T1-weighted, gadolinium-enhanced magnetic resonance images. These contours were drawn twice by each physician. The volume and center of mass coordinates for each gross tumor volume were extracted and a Boolean analysis was performed to measure the degree of volume overlap.
The median standard deviation in gross tumor volumes across observers was 6.1% of the average volume (range: 1.8%-24.9%). There was remarkably little variation in the 3D position of the gross tumor volume center of mass. For the 15 patients, the standard deviation of the 3D distance between centers of mass ranged from 0.06 mm to 1.7 mm (median 0.1mm). Boolean analysis demonstrated that 53% to 90% of the gross tumor volume was common to all observers (median overlap: 79%). The standard deviation in gross tumor volumes on repeat contouring was 4.8% (range: 0.1-14.4%) with a standard deviation change in the position of the center of mass of 0.4mm (range: 0mm-2.6mm) and a median overlap of 93% (range: 73%-98%).
Although significant inter-observer differences were seen in gross tumor volume definition of adult soft-tissue sarcoma, the center of mass of these volumes was remarkably consistent. Variations in volume definition did not correlate with tumor size. Radiation oncologists should not hesitate to review their contours with a colleague (surgeon, radiologist or fellow radiation oncologist) to ensure that they are not outliers in sarcoma gross tumor volume definition. Protocols should take into account variations in volume definition when considering tighter clinical target volumes.
[Show abstract][Hide abstract] ABSTRACT: class="para" id="par0005">Residency in oncology takes five years in France. Each resident has already studied medicine for six years before, making the total time of eleven years to complete their education. During that time, we receive courses about general oncology: cellular and molecular biology, genetics, pharmacology, medical imaging, stem cells, cell death, oncogenesis, immunity, angiogenesis, pathology, epidemiology, and chemotherapy. Specific courses about radiophysics, radiobiology, brachytherapy and radiation therapy innovations are also mandatory.
Reports of Practical Oncology and Radiotherapy 08/2012; 17(5). DOI:10.1016/j.rpor.2012.07.006
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