Isotoxic Dose Escalation in the Treatment of Lung Cancer by Means of Heterogeneous Dose Distributions in the Presence of Respiratory Motion

Journal Article · Tue Nov 01 04:00:00 EDT 2011 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2010.12.001· OSTI ID:21590467

Baker, Mariwan; Nielsen, Morten ^[1]; Hansen, Olfred ^[2]; Jahn, Jonas Westberg ^[1]; Korreman, Stine ^[3]; Brink, Carsten ^[1]

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1. Laboratory of Radiation Physics, Odense University Hospital, Odense (Denmark)
2. Department of Oncology, Odense University Hospital, Odense (Denmark)
3. Department of Radiation Oncology, Copenhagen University Hospital, Copenhagen (Denmark)

Purpose: To test, in the presence of intrafractional respiration movement, a margin recipe valid for a homogeneous and conformal dose distribution and to test whether the use of smaller margins combined with heterogeneous dose distributions allows an isotoxic dose escalation when respiratory motion is considered. Methods and Materials: Twenty-three Stage II-III non-small-cell lung cancer patients underwent four-dimensional computed tomography scanning. The gross tumor volume and clinical target volume (CTV) were outlined in the mid-ventilation phase. The CTV-to-planning target volume (PTV) margin was calculated by use of a standard margin recipe and the patient-specific respiration pattern. Standard three-dimensional treatment plans were generated and recalculated on the remaining respiration phases. The planning was repeated for a CTV-to-PTV margin decreased by 2.5 and 5 mm relative to the initial margin in all directions. Time-averaged dose-volume histograms (four-dimensional dose-volume histograms) were calculated to evaluate the CTV-to-PTV margin. Finally, the dose was escalated in the plans with decreased PTV such that the mean lung dose (predictor of radiation-induced pneumonitis) was equal to mean lung dose in the plan by use of the initially calculated margin. Results: A reduction of the standard margin by 2.5 mm compared with the recipe resulted in too low of a minimum dose for some patients. A combination of dose escalation and use of heterogeneous dose distribution was able to increase the minimum dose to the target by approximately 10% and 20% for a CTV-to-PTV margin reduction of 2.5 mm and 5.0 mm, respectively. Conclusion: The margin recipe is valid for intrafractional respiration-induced tumor motions. It is possible to increase the dose to the target without increased mean lung dose with an inhomogeneous dose distribution.

• OSTI ID: 21590467
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 3 Vol. 81; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
BODY
COMPUTERIZED TOMOGRAPHY
DIAGNOSTIC TECHNIQUES
DISEASES
DOSES
LUNGS
NEOPLASMS
ORGANS
PNEUMONITIS
RADIATION DOSE DISTRIBUTIONS
RADIATION DOSES
RESPIRATION
RESPIRATORY SYSTEM
TOMOGRAPHY