Clinical introduction of Monte Carlo treatment planning: A different prescription dose for non-small cell lung cancer according to tumor location and size

van der Voort van Zyp, Noëlle C.; Hoogeman, Mischa S.; van de Water, Steven; Levendag, Peter C.; van der Holt, Bronno; Heijmen, Ben J.M.; Nuyttens, Joost J.

doi:10.1016/j.radonc.2010.04.009

« Previous Next »Radiotherapy & Oncology
Volume 96, Issue 1 , Pages 55-60, July 2010

Clinical introduction of Monte Carlo treatment planning: A different prescription dose for non-small cell lung cancer according to tumor location and size☆

Noëlle C. van der Voort van Zyp
- Department of Radiation Oncology, Erasmus MC-Daniel den Hoed Cancer Center, Rotterdam, The Netherlands
- Corresponding author. Address: Department of Radiation Oncology, Erasmus MC-Daniel den Hoed Cancer Center, Groene Hilledijk 301 3075 EA Rotterdam, The Netherlands.
Mischa S. Hoogeman
- Department of Radiation Oncology, Erasmus MC-Daniel den Hoed Cancer Center, Rotterdam, The Netherlands
Steven van de Water
- Department of Radiation Oncology, Erasmus MC-Daniel den Hoed Cancer Center, Rotterdam, The Netherlands
Peter C. Levendag
- Department of Radiation Oncology, Erasmus MC-Daniel den Hoed Cancer Center, Rotterdam, The Netherlands
Bronno van der Holt
- Department of Trials & Statistics, Erasmus MC-Daniel den Hoed Cancer Center, Rotterdam, The Netherlands
Ben J.M. Heijmen
- Department of Radiation Oncology, Erasmus MC-Daniel den Hoed Cancer Center, Rotterdam, The Netherlands
Joost J. Nuyttens
- Department of Radiation Oncology, Erasmus MC-Daniel den Hoed Cancer Center, Rotterdam, The Netherlands

Received 14 December 2009; received in revised form 12 March 2010; accepted 5 April 2010. published online 30 April 2010.

Abstract

Purpose

To provide a prescription dose for Monte Carlo (MC) treatment planning in patients with non-small-cell lung cancer according to tumor size and location.

Methods

Fifty-three stereotactic radiotherapy plans designed using the equivalent path-length (EPL) algorithm were re-calculated using MC. Plans were compared by the minimum dose to 95% of the PTV (D95), the heterogeneity index (HI) and the mean dose to organs at risk (OARs). Based on changes in D95, the prescription dose was converted from EPL to MC. Based on changes in HI, we examined the feasibility of MC prescription to plans re-calculated but not re-optimized with MC.

Results

The MC fraction dose for peripheral tumors is 16–18Gy depending on tumor size. For central tumors the MC dose was reduced less than for peripheral tumors. The HI decreased on average by 4–9% in peripheral tumors and 3–5% in central tumors. The mean dose to OARs was lower for MC than EPL, and correlated strongly (R²=0.98–0.99).

Conclusion

For the conversion from EPL to MC we recommend a separate prescription dose according to tumor size. MC optimization is not required if a HI⩾70% is accepted. Dose constraints to OARs can be easily converted due to the high EPL–MC correlation.

Keywords: Monte Carlo, Lung cancer, Stereotactic radiotherapy, Dose prescription