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The use of aperture shape controller and convergence mode in radiotherapy treatment planning

Published online by Cambridge University Press:  11 December 2020

Maija Rossi Open the ORCID record for Maija Rossi [Opens in a new window]  and
Eeva Boman Open the ORCID record for Eeva Boman [Opens in a new window]
Maija Rossi*
Affiliation:
Department of Medical Physics, Tampere University Hospital, Teiskontie 35, PO BOX 2000, 33521Tampere, Finland Department of Oncology, Tampere University Hospital, Teiskontie 35, PO BOX 2000, 33521Tampere, Finland
Eeva Boman
Affiliation:
Department of Medical Physics, Tampere University Hospital, Teiskontie 35, PO BOX 2000, 33521Tampere, Finland Department of Oncology, Tampere University Hospital, Teiskontie 35, PO BOX 2000, 33521Tampere, Finland
*
Author for correspondence: Maija Rossi, Tampere University Hospital, Teiskontie 35, PO BOX 2000, 33521Tampere, Finland. E-mail: [email protected]
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Abstract

Aim:

Studying the use of Aperture Shape Controller (ASC) and Convergence Mode (CM) in Eclipse (Varian Medical System) in terms of plan quality and complexity of volumetric modulated arc therapy (VMAT).

Materials and methods:

Forty VMAT plans were re-optimised for the prostate, prostate + lymph nodes, breast and head & neck patients retrospectively, changing the ASC settings (off, moderate, very high) and CM settings (off, on and extended).

Results:

Using ‘on’ or ‘extended’ CM increased plan quality in terms of planning target volume homogeneity and low-dose spread to the organs at risk (OAR). ‘Extended’ CM increased the optimisation time 4·3-fold compared to ‘on’, and deteriorated the plan quality in several simple planning cases. ‘Moderate’ ASC decreased plan complexity with minor effect on plan quality compared to ‘off’, but ‘very high’ ASC had larger adverse dosimetric effects. However, the ASC decreased the plan complexity only if the CM was turned ‘on’.

Findings:

Using ‘on’ CM increases the plan quality but using ‘extended’ CM is not recommended. The ‘moderate’ ASC decreased complexity without significant adverse effects on plan quality, and even ‘very high’ ASC may be used when plan simplicity is prioritised. However, if CM is not used, the ASC should also be turned off.

Keywords

aperture shape controllerconvergence modeplan complexityplan quality
Type
Original Article
Information
Journal of Radiotherapy in Practice , Volume 21 , Issue 2 , June 2022 , pp. 171 - 178
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Copyright
© The Author(s), 2020. Published by Cambridge University Press

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Footnotes

This research received no specific grant from any funding agency, commercial or not-for-profit sectors.

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