Catharine H Clark1, Mohammad Hussein2, Yatman Tsang3, Russell Thomas4, Dean Wilkinson3, Graham Bass4, Julia Snaith4, Clare Gouldstone4, Steve Bolton5, Rebecca Nutbrown4, Karen Venables3, Andrew Nisbet2. 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.
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.
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.
Authors: Gregory Smyth; Philip M Evans; Jeffrey C Bamber; Henry C Mandeville; A Rollo Moore; Liam C Welsh; Frank H Saran; James L Bedford Journal: Phys Med Biol Date: 2019-04-05 Impact factor: 3.609
Authors: Sophie Chiavassa; Igor Bessieres; Magali Edouard; Michel Mathot; Alexandra Moignier Journal: Br J Radiol Date: 2019-07-24 Impact factor: 3.039
Authors: Conor K McGarry; Christina E Agnew; Mohammad Hussein; Yatman Tsang; Alan McWilliam; Alan R Hounsell; Catharine H Clark Journal: Br J Radiol Date: 2015-10-29 Impact factor: 3.039
Authors: Conor K McGarry; Christina E Agnew; Mohammad Hussein; Yatman Tsang; Alan R Hounsell; Catharine H Clark Journal: Br J Radiol Date: 2016-04-13 Impact factor: 3.039
Authors: Catharine H Clark; Edwin G A Aird; Steve Bolton; Elizabeth A Miles; Andrew Nisbet; Julia A D Snaith; Russell A S Thomas; Karen Venables; David I Thwaites Journal: Br J Radiol Date: 2015-09-02 Impact factor: 3.039