Andrew Pullar

An innovative approach for locally advanced stage III cutaneous melanoma: radiotherapy, followed by nodal dissection

Patients with advanced nodal melanoma are typically managed with a regional nodal dissection; however, they have a high rate of distant relapse after surgery. This study assesses the role of preoperative radiotherapy to assist with the regional control in this subset of patients. Patients who had histologically confirmed stage III malignant melanoma and were treated with preoperative radiotherapy between 2004 and 2011 were eligible. All patients were staged with computer tomography and most with [18F]-fluorodeoxyglucose (FDG) PET. Patients received preoperative radiotherapy, followed by a planned regional dissection at 12–14 weeks from completion with assessment of clinical, radiological and pathological responses. The primary outcome measure was the 1-year actuarial in-field control. There were 12 patients, with nine having disease of the axilla. All patients received radiotherapy up to a median dose of 48 Gy in 20 fractions, with seven patients achieving a partial clinical response. Ten patients proceeded to surgery, with four patients developing minor wound complications. The FDG-PET response did not appear to correlate with the pathological response. The 1-year in-field control rate was 92% (95% confidence interval 54–99) and the 1-year relapse-free survival was 54% (95% confidence interval 21–78). For selected patients with high-volume regional disease, we have successfully used preoperative radiotherapy, followed by a nodal dissection. Whether this type of protocol is of value in a more general group of patients with high-volume regional disease is currently under investigation.

Development and initial evaluation of a novel 3D volumetric outlining system

The novel three-dimensional (3D) radiotherapy interactive outlining tool allows volumes to be created from a handful of points within axial, sagittal and coronal planes. 3D volumetric visualisation allows users to directly manipulate the resulting volume using innovative-sculpting tools. This paper discusses the development and initial evaluation of the software ahead of formal clinical testing. User feedback was collated as part of the software development phase to ensure clinical suitability, define user training strategies and identify best practice. A loosely structured format was adopted with leading descriptive questions aiming to generate suggestions for improvements and initiate further discussion. The four participants reported great satisfaction and value in being able to use all three planes for outlining, although orientation in 3D was evidently a problem. All participants felt that the software was capable of producing acceptable outlines rapidly and that the multi-planar capability allowed for improved outlining of the prostate apex. Mesh generation from a small number of points placed on a range of planes is a rapid and effective means of target delineation. Multi-slice volume sculpting and 3D orientation is challenging and may indicate a need for a paradigm shift in anatomy and computed tomography training.

Inter- and intra-fraction motion in stereotactic body radiotherapy for spinal and paraspinal tumours using cone-beam CT and positional correction in six degrees of freedom

Stereotactic body radiotherapy (SBRT) for spinal tumours delivers high doses per fraction to targets in close proximity to neural tissue. With steep dose gradients, small changes in position can confer significant dosimetric impact on adjacent structures. We analysed positioning error in consecutively treated patients on a strict image‐guidance protocol with online correction in 6 degrees of freedom (6‐DOF).

Technique and early clinical outcomes for spinal and paraspinal tumours treated with stereotactic body radiotherapy

We report technique and early clinical results of stereotactic body radiotherapy (SBRT) from Princess Alexandra Hospital. SBRT involves the precise delivery of highly conformal and image-guided external beam radiotherapy with high doses per fraction. It is increasingly being applied in management of spinal tumours. Thirty-six courses of spine SBRT in 34 patients were delivered between May 2010 and December 2013. Mean patient age was 58 years. Treatment was predominantly for metastatic disease, applied in de novo (n=22), retreatment (n=14) and postoperative (n=8) settings. Prescribed doses included 18-30 Gy in 1-5 fractions. SBRT technique evolved during the study period, resulting in a relative dose escalation. No severe acute toxicities were observed. At median follow-up of 7.4 months (range: 1.7-22.2), no late radiation myelopathy was observed. Risk of new/worsening vertebral compression fractures was 22% (n=8) and was significantly associated with increasing Spinal Instability Neoplastic Scores (p=0.0002). In-field control was 86% with relapse occurring at a median interval of 2.8 months (range: 1.9-4.7). Thirteen patients (36%) died and median overall survival has not been reached. SBRT is an evolving technology with promising early efficacy and safety results. The outcomes of this series are comparable with international literature, and await longer follow-up.

Prospective analysis of the utility of 18‐FDG PET in Merkel cell carcinoma of the skin: A Trans Tasman Radiation Oncology Group Study, TROG 09:03

TROG 09.03 prospectively studied the utility of Fluorine‐18 Fluorodeoxyglucose (18‐FDG) PET in the management of Merkel cell carcinoma of skin.

Clinical implications of the overshoot effect for treatment plan delivery and patient-specific quality assurance for step-and-shoot IMRT

In this work, overshoot and undershoot effects associated with step‐and‐shoot IMRT (SSIMRT) delivery on a Varian Clinac 21iX are investigated, and their impact on patient‐specific QA point dose measurements and treatment plan delivery are evaluated. Pinnacle3 SSIMRT plans consisting of 5, 10, and 15 identical 5×5 cm2 MLC defined segments and MU/segment values of 5 MU, 10 MU, and 20 MU were utilized and delivered at 600/300 MU/min. Independent of the number of segments the overshoot and undershoot at 600 MU/min were approximately ±10%,±5%, and ±2.5% for 5 MU/segment, 10 MU/segment, and 20 MU/segment, respectively. At 300 MU/min, each of these values is approximately halved. Interfractional variation of these effects (10 fractions), as well as dosimetric variations for intermediate segments, are reduced at the lower dose rate. QA point‐dose measurements for a sample (n=29) of head and neck SSIMRT beams were on average 2.9% (600 MU/min) and 1.7% (300 MU/min) higher than Pinnacle3 planned doses. In comparison for prostate beams (n=46), measured point doses were 0.8% (600 MU/min) and 0.4% (300 MU/min) higher. The reduction in planned‐measured point‐dose discrepancies at 300 MU/min can be attributed in part to the inclusion of the first segment (overshoot) in the admixture of segments that deliver measured dose. Pinnacle3 plans for 10/9 head and neck/prostate treatments were adjusted by ±0.5 MU to include the effects of overshoot and undershoot at 600 MU/min. Comparing original and adjusted plans for each site indicated that the original plan was preferred in 70% and 89% of head and neck and prostate cases, respectively. The disparity between planned and delivered treatment that this suggests can potentially be mitigated by treating SSIMRT at a dose rate below 600 MU/min. PACS number(s): 87.55.Qr, 87.56.bd, 87.56.N‐In this work, overshoot and undershoot effects associated with step-and-shoot IMRT (SSIMRT) delivery on a Varian Clinac 21iX are investigated, and their impact on patient-specific QA point dose measurements and treatment plan delivery are evaluated. Pinnacle3 SSIMRT plans consisting of 5, 10, and 15 identical 5×5 cm2 MLC defined segments and MU/segment values of 5 MU, 10 MU, and 20 MU were utilized and delivered at 600/300 MU/min. Independent of the number of segments the overshoot and undershoot at 600 MU/min were approximately ±10%,±5%, and ±2.5% for 5 MU/segment, 10 MU/segment, and 20 MU/segment, respectively. At 300 MU/min, each of these values is approximately halved. Interfractional variation of these effects (10 fractions), as well as dosimetric variations for intermediate segments, are reduced at the lower dose rate. QA point-dose measurements for a sample (n=29) of head and neck SSIMRT beams were on average 2.9% (600 MU/min) and 1.7% (300 MU/min) higher than Pinnacle3 planned doses. In comparison for prostate beams (n=46), measured point doses were 0.8% (600 MU/min) and 0.4% (300 MU/min) higher. The reduction in planned-measured point-dose discrepancies at 300 MU/min can be attributed in part to the inclusion of the first segment (overshoot) in the admixture of segments that deliver measured dose. Pinnacle3 plans for 10/9 head and neck/prostate treatments were adjusted by ±0.5 MU to include the effects of overshoot and undershoot at 600 MU/min. Comparing original and adjusted plans for each site indicated that the original plan was preferred in 70% and 89% of head and neck and prostate cases, respectively. The disparity between planned and delivered treatment that this suggests can potentially be mitigated by treating SSIMRT at a dose rate below 600 MU/min. PACS number(s): 87.55.Qr, 87.56.bd, 87.56.N.