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Abstract
Knowledge of the accuracy of dose calculations in intensity-modulated radiotherapy
of the head and neck is essential for clinical confidence in these highly conformal
treatments. High dose gradients are frequently placed very close to critical structures,
such as the spinal cord, and good coverage of complex shaped nodal target volumes
is important for long term-local control.
A phantom study is presented comparing the performance of standard clinical pencil-beam
and collapsed-cone dose algorithms to Monte Carlo calculation and three-dimensional
gel dosimetry measurement. Calculations and measurements are individually normalized
to the median dose in the primary planning target volume, making this a purely relative
study. The phantom simulates tissue, air and bone for a typical neck section and is
treated using an inverse-planned 5-field IMRT treatment, similar in character to clinically
used class solutions.
Results indicate that the pencil-beam algorithm fails to correctly model the relative
dose distribution surrounding the air cavity, leading to an cverestimate of the target
coverage. The collapsed-cone and Monte Carlo results are very similar, indicating
that the clinical collapsed-cone algorithm is perfectly sufficient for routine clinical
use. The gel measurement shows generally good agreement with the collapsed-cone and
Monte Carlo calculated dose, particularly in the spinal cord dose and nodal target
coverage, thus giving greater confidence in the use of this class solution.
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References
- Contemporary IMRT.0750310049 Institute of Physics Publishing, Bristol UK2004
- Patterns of failure in patients receiving definitive and postoperative IMRT for head-and neck cancer.I J Radiation Oncology Biol Phys. 2003; 55: 312-321
- Intensity-Modulated Radiation Therapy for Head and Neck Cancer.in: AAPM Summer School Proceedings, Colorado Springs, Colorado2003
- Optimisation of radiotherapy for carcinoma of the parotid gland: a comparison of conventional, three-dimensional conformal, and intensity-modulated techniques.Radiother & Oncol. 2001; 60: 163-172
- Improvements in target coverage and reduced spinal cord irradiation using intensity-modulated radiotherapy (IMRT) in patients with carcinoma of the thyroid gland.Radiother & Onco. 2001; 60: 173-180
- Dosimetric presictors of xerostomia for head-and-neck cancer patients treated with the SMART (simultaneous modulated accelerated radiation therapy) boost technique.I J Radiation Oncology Biol Phys. 2003; 56: 136-144
- Quality of life after parotid-sparing IMRT for head-and-neck cancer: a prospective longitudinal study.I J Radiation Oncology Biol Phys. 2003; 57: 61-70
- Intensity-modulated radiotherapy improves target coverage, spinal cord sparing and allows dose escalation in patients with locally advanced cancer of the larynx.Radiother & Oncol. 2004; 70: 189-198
- Is sensorineural hearing loss a possible side effect of nasopharyngeal and parotid irradiation? A systematic review of the literature.Radiother & Oncol. 2002; 65: 1-7
- Assessment of different IMRT boost delivery methods on target coverage and normal-tissue sparing.I J Radiation Oncology Biol Phys. 2003; 57: 1480-1491
- Comparative dosimetric evaluation of the simultaneous integrated boost with photon intensity modulation in head and neck cancer patients.Radiother & Oncol. 2003; 69: 267-275
- The effect of dose calculation accuracy on inverse treatment planning.Phys Med Biol. 2002; 47: 391-407
- Monte Carlo evaluation of 6 MV intensity modulated radiotherapy plans for head and neck and lung treatments.Med Phys. 2002; 29: 2705-2717
- Monte Carlo-Based Dosimetry for H&N Patients Treated with SIB-IMRT.I J Radiation Oncology Biol Phys. 2003; 57: S209
- Dose verification of an IMRT treatment planning system with BEAM EGS4-based Monte Carlo code.Med Phys. 2003; 30: 144-157
- Comparison of IMRT optimisation based on a pencil beam and a superposition algorithm.Med Phys. 2003; 30: 1909-1913
- Importance of accurate dose calculations outside segment edges in intensity modulated radiotherapy treatment planning.Radiother & Oncol. 2003; 69: 305-314
- Routine use of Monte Carlo dose computation for head and neck IMRT optimization.I J Radiation Oncology Biol Phys. 2003; 57: S208
- The use of gel dosimetry for verification of electron and photon treatment plans in carcinoma of the scalp.Phys Med Biol. 2004; 49: 1625-1635
- Measurement of radiation dose distributions by nuclear magnetic resonance (NMR) imaging.Phys Med Biol. 1984; 29: 1189-1197
- Magnetic resonance imaging of radiation dose distributions using a Polymer-gel Dosimeter.Phys Med Biol. 1994; 39: 1437-1455
- Polymer gels for magnetic resonance imaging of radiation dose distributions at normal room atmosphere.Phys Med Biol. 2001; 47: 3105-3113
- Three-dimensional dosimetry using polymer gel and magnetic resonance imaging applied to the verification of conformal radiation therapy in head-and-neck cancer.Radiother & Oncol. 1998; 48: 283-291
- Treatment planning dose verification using MRI gel dosimetry and a Barex head and neck phantom.in: DosGel '99 1st Int. workshop on Radiation Therapy Gel Dosimetry, Lexington, Kentucky, Canadian Organisation of Medical Physicists1999
- Limitations of a pencil beam approach to photon dose calculations in lung tissue.Phys Med Biol. 1995; 40: 1411-1420
- Barex barrier resins barrier properties, Naperville, Il, USA.2000
- Preliminary study on the use of an inhomogeneous anthropomorphic Fricke gel phantom and 3D magnetic resonance dosimetry for verification of IMRT treatment plans.Phys Med Biol. 2002; 47: N67-N77
- IMRT treatments assessed with a Monte Carlo dose calculation engine.Phys Med Biol. 2005; 50: 817-830
- 3D electron dose calculation using a voxel based Monte Carlo algorithm (VMC).Med Phys. 1996; 23: 445-457
- Clinical implementation of dynamic and step-and-shoot IMRT to treat prostate cancer with high risk of pelvic lymph node involvement.Radiother & Oncol. 2004; 70: 1-10
- A polymer gel prepared under normal levels of oxygenation: basic studies.in: Prelim. Proc. 2nd Int. Conf. Radiotherapy Gel Dosimetry, Brisbane, Australia, Queensland University of Technology2001
- A technique for the quantitative evaluation of dose distributions.Med Phys. 1998; 25: 656-661
- Dosimetric verification of a commercial collapsed cone algorithm in simulated clinical situations.Radiother & Oncol. 2004; 73: 79-88
- On the relationship between spatial dose integrity and the temporal instability of polymer gel dosimeters.Med Phys. 2004; 49: 4507-4522
Article info
Publication history
Accepted:
July 17,
2006
Received in revised form:
July 12,
2006
Received:
May 2,
2006
Identification
Copyright
© 2006 Associazione Italiana di Fisica Medica. Published by Elsevier Inc. All rights reserved.
