A theoretical investigation of adequate range uncertainty margins in proton treatment planning to preserve tumor control probability Conference Paper
| Authors: | Taasti, V. T.; Jeong, J.; Jackson, A.; Deasy, J. O. |
| Title: | A theoretical investigation of adequate range uncertainty margins in proton treatment planning to preserve tumor control probability |
| Conference Title: | 18th Acta Oncologica Conference on Biology-Guided Adaptive Radiotherapy (BiGART2019) |
| Abstract: | Background: Proton dose distributions are sensitive to range uncertainties, resulting in margins added to ensure adequate tumor control probability (TCP). We investigated the required margin and dose shape needed to ensure adequate TCP, for representative tumor cell distributions in the clinical target volume (CTV). Material and methods: A mechanistic tumor response model, validated for lung tumors, was used to estimate TCP. The tumor cell distribution ((Formula presented.)) was assumed to decrease exponentially in the CTV with decay parameter (Formula presented.) toward the outer border ((Formula presented.)). It was investigated if a gradual dose fall-off could reduce the dose to normal tissues outside the CTV, while achieving adequate TCP. For various values of (Formula presented.) and (Formula presented.) we derived adequate uniform dose margins ((Formula presented.)), coupled to linear dose fall-off regions ((Formula presented.) (Formula presented.) cm), that ensured (Formula presented.) while delivering the least mean dose outside the CTV. To account for variabilities in patients and tumor types, variable probabilities ((Formula presented.)) of finding tumor cells in the non-GTV part of the CTV for a given patient were also tested. Dose from a single beam or two opposing beams was simulated under the influence of a typical stopping power ratio uncertainty of 3.5%. Results: For large (Formula presented.) and (Formula presented.) a dose distribution with a shallower dose fall-off ((Formula presented.)) was advantageous, and (Formula presented.) could be smaller than (Formula presented.) In the case of small (Formula presented.) values, however, a conventional dose distribution ((Formula presented.)) would generally perform better. For no CTV, (Formula presented.) cm in the case of two opposing beams, while it was 0.7 cm for a single beam, however, for two opposing beams (Formula presented.) cm ((Formula presented.) cm), while it was zero for a single beam. Conclusion: The details of the underlying cancer cell distribution characteristics do impact the adequate dose arrangements, and for opposing beams a non-conventional dose distribution shape is often advantageous. © 2019, © 2019 Acta Oncologica Foundation. |
| Journal Title | Acta Oncologica |
| Volume: | 58 |
| Issue: | 10 |
| Conference Dates: | 2019 May 22-24 |
| Conference Location: | Aarhus, Denmark |
| ISBN: | 0284-186X |
| Publisher: | Informa Healthcare |
| Date Published: | 2019-01-01 |
| Start Page: | 1446 |
| End Page: | 1450 |
| Language: | English |
| DOI: | 10.1080/0284186x.2019.1627415 |
| PUBMED: | 31241385 |
| PROVIDER: | scopus |
| DOI/URL: | |
| Notes: | Article -- Export Date: 2 December 2019 -- Source: Scopus |
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