open access

Vol 17, No 3 (2012)
Technical Notes
Published online: 2012-05-01
Submitted: 2011-06-20
Get Citation

A study on conventional IMRT and RapidArc treatment planning techniques for head and neck cancers

S.A. Syam Kumar, Nagarajan Vivekanandan, Padmanaban Sriram
DOI: 10.1016/j.rpor.2012.01.009
·
Rep Pract Oncol Radiother 2012;17(3):168-175.

open access

Vol 17, No 3 (2012)
Technical Notes
Published online: 2012-05-01
Submitted: 2011-06-20

Abstract

Aim

To evaluate the performance of volumetric arc modulation with RapidArc against conventional IMRT for head and neck cancers.

Background

RapidArc is a novel technique that has recently been made available for clinical use. Planning study was done for volumetric arc modulation with RapidArc against conventional IMRT for head and neck cancers.

Materials and methods

Ten patients with advanced tumors of the nasopharynx, oropharynx, and hypopharynx were selected for the planning comparison study. PTV was delineated for two different dose levels and planning was done by means of simultaneously integrated boost technique. A total dose of 70[[ce:hsp sp="0.25"/]]Gy was delivered to the boost volume (PTV boost) and 57.7[[ce:hsp sp="0.25"/]]Gy to the elective PTV (PTV elective) in 35 equal treatment fractions. PTV boost consisted of the gross tumor volume and lymph nodes containing visible macroscopic tumor or biopsy-proven positive lymph nodes, whereas the PTV elective consisted of elective nodal regions. Planning was done for IMRT using 9 fields and RapidArc with single arc, double arc. Beam was equally placed for IMRT plans. Single arc RapidArc plan utilizes full 360° gantry rotation and double arc consists of 2 co-planar arcs of 360° in clockwise and counter clockwise direction. Collimator was rotated from 35 to 45° to cover the entire tumor, which reduced the tongue and groove effect during gantry rotation. All plans were generated with 6[[ce:hsp sp="0.25"/]]MV X-rays for CLINAC 2100 Linear Accelerator. Calculations were done in the Eclipse treatment planning system (version 8.6) using the AAA algorithm.

Results

Double arc plans show superior dose homogeneity in PTV compared to a single arc and IMRT 9 field technique. Target coverage was almost similar in all the techniques. The sparing of spinal cord in terms of the maximum dose was better in the double arc technique by 4.5% when compared to the IMRT 9 field and single arc techniques. For healthy tissue, no significant changes were observed between the plans in terms of the mean dose and integral dose. But RapidArc plans showed a reduction in the volume of the healthy tissue irradiated at V15[[ce:hsp sp="0.25"/]]Gy (5.81% for single arc and 4.69% for double arc) and V20[[ce:hsp sp="0.25"/]]Gy (7.55% for single arc and 5.89% for double arc) dose levels when compared to the 9-Field IMRT technique. For brain stem, maximum dose was similar in all the techniques. The average MU (±SD) needed to deliver the dose of 200[[ce:hsp sp="0.25"/]]cGy per fraction was 474[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]80[[ce:hsp sp="0.25"/]]MU and 447[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]45[[ce:hsp sp="0.25"/]]MU for double arc and single arc as against 948[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]162[[ce:hsp sp="0.25"/]]MU for the 9-Field IMRT plan. A considerable reduction in maximum dose to the mandible by 6.05% was observed with double arc plan. Double arc shows a reduction in the parotid mean dose when compared with single arc and IMRT plans.

Conclusion

RapidArc using double arc provided a significant sparing of OARs and healthy tissue without compromising target coverage compared to IMRT. The main disadvantage with IMRT observed was higher monitor units and longer treatment time.

Abstract

Aim

To evaluate the performance of volumetric arc modulation with RapidArc against conventional IMRT for head and neck cancers.

Background

RapidArc is a novel technique that has recently been made available for clinical use. Planning study was done for volumetric arc modulation with RapidArc against conventional IMRT for head and neck cancers.

Materials and methods

Ten patients with advanced tumors of the nasopharynx, oropharynx, and hypopharynx were selected for the planning comparison study. PTV was delineated for two different dose levels and planning was done by means of simultaneously integrated boost technique. A total dose of 70[[ce:hsp sp="0.25"/]]Gy was delivered to the boost volume (PTV boost) and 57.7[[ce:hsp sp="0.25"/]]Gy to the elective PTV (PTV elective) in 35 equal treatment fractions. PTV boost consisted of the gross tumor volume and lymph nodes containing visible macroscopic tumor or biopsy-proven positive lymph nodes, whereas the PTV elective consisted of elective nodal regions. Planning was done for IMRT using 9 fields and RapidArc with single arc, double arc. Beam was equally placed for IMRT plans. Single arc RapidArc plan utilizes full 360° gantry rotation and double arc consists of 2 co-planar arcs of 360° in clockwise and counter clockwise direction. Collimator was rotated from 35 to 45° to cover the entire tumor, which reduced the tongue and groove effect during gantry rotation. All plans were generated with 6[[ce:hsp sp="0.25"/]]MV X-rays for CLINAC 2100 Linear Accelerator. Calculations were done in the Eclipse treatment planning system (version 8.6) using the AAA algorithm.

Results

Double arc plans show superior dose homogeneity in PTV compared to a single arc and IMRT 9 field technique. Target coverage was almost similar in all the techniques. The sparing of spinal cord in terms of the maximum dose was better in the double arc technique by 4.5% when compared to the IMRT 9 field and single arc techniques. For healthy tissue, no significant changes were observed between the plans in terms of the mean dose and integral dose. But RapidArc plans showed a reduction in the volume of the healthy tissue irradiated at V15[[ce:hsp sp="0.25"/]]Gy (5.81% for single arc and 4.69% for double arc) and V20[[ce:hsp sp="0.25"/]]Gy (7.55% for single arc and 5.89% for double arc) dose levels when compared to the 9-Field IMRT technique. For brain stem, maximum dose was similar in all the techniques. The average MU (±SD) needed to deliver the dose of 200[[ce:hsp sp="0.25"/]]cGy per fraction was 474[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]80[[ce:hsp sp="0.25"/]]MU and 447[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]45[[ce:hsp sp="0.25"/]]MU for double arc and single arc as against 948[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]162[[ce:hsp sp="0.25"/]]MU for the 9-Field IMRT plan. A considerable reduction in maximum dose to the mandible by 6.05% was observed with double arc plan. Double arc shows a reduction in the parotid mean dose when compared with single arc and IMRT plans.

Conclusion

RapidArc using double arc provided a significant sparing of OARs and healthy tissue without compromising target coverage compared to IMRT. The main disadvantage with IMRT observed was higher monitor units and longer treatment time.

Get Citation

Keywords

RapidArc; IMRT; Planning study; Head and neck cancers

About this article
Title

A study on conventional IMRT and RapidArc treatment planning techniques for head and neck cancers

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 17, No 3 (2012)

Pages

168-175

Published online

2012-05-01

DOI

10.1016/j.rpor.2012.01.009

Bibliographic record

Rep Pract Oncol Radiother 2012;17(3):168-175.

Keywords

RapidArc
IMRT
Planning study
Head and neck cancers

Authors

S.A. Syam Kumar
Nagarajan Vivekanandan
Padmanaban Sriram

Important: This website uses cookies. More >>

The cookies allow us to identify your computer and find out details about your last visit. They remembering whether you've visited the site before, so that you remain logged in - or to help us work out how many new website visitors we get each month. Most internet browsers accept cookies automatically, but you can change the settings of your browser to erase cookies or prevent automatic acceptance if you prefer.

By "Via Medica sp. z o.o." sp.k., ul. Świętokrzyska 73, 80–180 Gdańsk, Poland
tel.:+48 58 320 94 94, fax:+48 58 320 94 60, e-mail: journals@viamedica.pl