Current status of intra-cranial stereotactic radiotherapy and stereotactic radiosurgery in Australia and New Zealand: key considerations from a workshop and surveys

Abstract

Recently, there has been increased interest worldwide in the use of conventional linear accelerator (linac)-based systems for delivery of stereotactic radiosurgery/radiotherapy (SRS/SRT) contrasting with historical delivery in specialised clinics with dedicated equipment. In order to gain an understanding and define the current status of SRS/SRT delivery in Australia and New Zealand (ANZ) we conducted surveys and provided a single-day workshop. Prior to the workshop ANZ medical physicists were invited to complete two surveys: a departmental survey regarding SRS/SRT practises and equipment; and an individual survey regarding opinions on current and future SRS/SRT practices. At the workshop conclusion, attendees completed a second opinion-based survey. Workshop discussion and survey data were utilised to identify areas of consensus, and areas where a community consensus was unclear. The workshop was held on the 8th Sept 2020 virtually due to pandemic-related travel restrictions and was attended by 238 radiation oncology medical physicists from 39 departments. The departmental survey received 32 responses; a further 89 and 142 responses were received to the pre-workshop and post-workshop surveys respectively. Workshop discussion indicated a consensus that for a department to offer an SRS/SRT service, a minimum case load should be considered depending on availability of training, peer-review, resources and equipment. It was suggested this service may be limited to brain metastases only, with less common indications reserved for departments with comprehensive SRS/SRT programs. Whilst most centres showed consensus with treatment delivery techniques and image guidance, opinions varied on the minimum target diameter and treatment margin that should be applied.

Keywords: Australia; New Zealand; Stereotactic radiosurgery; Stereotactic radiotherapy; Survey.

Fig. 1

Cumulative total of departments offering SRS or SRT services over time based upon departmental survey results (32 respondents)

Fig. 2

Number of brain metastases patients treated in 2019 by the 26 departments who offer an SRS/SRT service compared to total other indicators treated including AVM arteriovenous malformation, Acoustic Neuroma, Trigeminal Neuralgia, GBM glioblastoma

Fig. 3

For the following survey results, more than one response was allowed: SRS/SRT treatment delivery device (31 responses), techniques used to deliver SRS/SRT (47 responses) and IGRT techniques used in SRS/SRT delivery (45 responses)

Fig. 4

Survey results regarding PTV margins used for SRS/SRT treatments (22 respondents)

Fig. 5

Off-axis distance limits used by those departments who limit the off-axis target distance away from isocentre in SIMT SRS (10 respondents)

Fig. 6

Frequency of performing a Winston-Lutz style test (25 respondents)

Fig. 7

Individual pre- and post-workshop survey results