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Estimation of monitor unit through analytical method for dynamic IMRT using control points as an effective parameter

Published online by Cambridge University Press:  02 March 2021

M. Athiyaman Open the ORCID record for M. Athiyaman [Opens in a new window] ,
A. Hemalatha Open the ORCID record for A. Hemalatha [Opens in a new window] ,
Arun Chougule Open the ORCID record for Arun Chougule [Opens in a new window] ,
Mary Joan Open the ORCID record for Mary Joan [Opens in a new window]  and
HS Kumar Open the ORCID record for HS Kumar [Opens in a new window]
M. Athiyaman*
Affiliation:
Radiological Physics, Sardar Patel Medical College, Bikaner, Rajasthan, India334003
A. Hemalatha
Affiliation:
Radiological Physics, Sardar Patel Medical College, Bikaner, Rajasthan, India334003
Arun Chougule
Affiliation:
Radiological Physics SMS Medical College and Hospital, Jaipur, Rajasthan, India302004
Mary Joan
Affiliation:
Radiological Physics SMS Medical College and Hospital, Jaipur, Rajasthan, India302004
HS Kumar
Affiliation:
Radiological Physics, Sardar Patel Medical College, Bikaner, Rajasthan, India334003
*
Author for correspondence: M. Athiyaman, Radiological Physics, Sardar Patel Medical College, Bikaner, Rajasthan, India334003. E-mail: athiyaman.bikaner@gmail.com
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Abstract

Introduction:

The control points (CP) play a significant role in the delivery of segmented based Intensity-Modulated Radiation Therapy (IMRT) delivery, particularly in dynamic mode. The number of segments is determined by control points and these segments will transfer from one to the other either during beam ON called dynamic delivery or during beam OFF called static delivery or step and shoot. This study was aimed at indirect estimation of the total monitor units (MU) to be delivered per field by exploiting the control points and also to find the MUs at any nth segment.

Materials and methods:

This study was performed in the Eclipse treatment planning software version 13.8.0. The details of control points, metre set weight per segment, leaf positions for each segment, field size, etc. were taken into consideration.

Results:

TPS calculated MU value and analytically estimated MU value were compared and the percentage of difference was estimated. The overall mean percentage of deviation was 1·03% between the TPS calculated method and the analytical method. The paired sample t-test was performed and, p-value <0·05, no significant difference was found. The analytical relationship determined to estimate the total number of MU delivered for any nth control point was also evaluated.

Conclusion:

The control points are a potential parameter in the conventional IMRT delivery. Through this study, we have addressed the indirect method to estimate the monitor units delivered per segment.

Keywords

computer-assisted radiotherapyradiotherapy dosageradiotherapy planning
Type
Original Article
Information
Journal of Radiotherapy in Practice , Volume 21 , Issue 3 , September 2022 , pp. 343 - 350
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Copyright
© The Author(s), 2021. Published by Cambridge University Press

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