A multi-institutional dosimetry audit of rotational intensity-modulated radiotherapy

Catharine H Clark; Mohammad Hussein; Yatman Tsang; Russell Thomas; Dean Wilkinson; Graham Bass; Julia Snaith; Clare Gouldstone; Steve Bolton; Rebecca Nutbrown; Karen Venables; Andrew Nisbet

doi:10.1016/j.radonc.2014.11.015

A multi-institutional dosimetry audit of rotational intensity-modulated radiotherapy

Radiother Oncol. 2014 Nov;113(2):272-8. doi: 10.1016/j.radonc.2014.11.015. Epub 2014 Nov 23.

Authors

Affiliations

¹ Department of Medical Physics, Royal Surrey County Hospital, Guildford, UK; National Physical Laboratory, London, UK; NCRI Radiotherapy Trials Quality Assurance Group, UK. Electronic address: catharine.clark@nhs.net.
² Department of Medical Physics, Royal Surrey County Hospital, Guildford, UK; Centre for Nuclear and Radiation Physics, University of Surrey, UK.
³ NCRI Radiotherapy Trials Quality Assurance Group, UK; Mount Vernon Hospital, Northwood, London, UK.
⁴ National Physical Laboratory, London, UK.
⁵ Christie Hospital, Manchester, UK; Institute of Physics and Engineering in Medicine, York, UK.

PMID: 25465734
DOI: 10.1016/j.radonc.2014.11.015

Abstract

Background: Rotational IMRT (VMAT and Tomotherapy) has now been implemented in many radiotherapy centres. An audit to verify treatment planning system modelling and treatment delivery has been undertaken to ensure accurate clinical implementation.

Material and methods: 34 institutions with 43 treatment delivery systems took part in the audit. A virtual phantom planning exercise (3DTPS test) and a clinical trial planning exercise were planned and independently measured in each institution using a phantom and array combination. Point dose differences and global gamma index (γ) were calculated in regions corresponding to PTVs and OARs.

Results: Point dose differences gave a mean (±sd) of 0.1±2.6% and 0.2±2.0% for the 3DTPS test and clinical trial plans, respectively. 34/43 planning and delivery combinations achieved all measured planes with >95% pixels passing γ<1 at 3%/3mm and rose to 42/43 for clinical trial plans. A statistically significant difference in γ pass rates (p<0.01) was seen between planning systems where rotational IMRT modelling had been designed for the manufacturer's own treatment delivery system and those designed independently of rotational IMRT delivery.

Conclusions: A dosimetry audit of rotational radiotherapy has shown that TPS modelling and delivery for rotational IMRT can achieve high accuracy of plan delivery.

Keywords: Audit; Detector arrays; IMRT; VMAT.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Medical Audit*
Patient Care Planning
Phantoms, Imaging
Radiometry
Radiotherapy Dosage
Radiotherapy, Intensity-Modulated* / standards