Dosimetric Comparison of Various Spot Placement Techniques in Proton Pencil Beam Scanning
Purpose: To present quantitative dosimetric evaluations of five proton pencil beam spot placement techniques. Materials and Methods: The spot placement techniques that were investigated include two grid-based (rectilinear grid and hexagonal grid, both commonly available in commercial planning system...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Particle Therapy Co-operative Group
2022-01-01
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| Series: | International Journal of Particle Therapy |
| Subjects: | |
| Online Access: | https://theijpt.org/doi/pdf/10.14338/IJPT-21-00022.1 |
| _version_ | 1797203612131131392 |
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| author | Mahboob ur Rehman, PhD Omar A. Zeidan, PhD Twyla Willoughby, PhD Sanford L. Meeks, PhD Patrick Kelly, MD Kevin Erhart, PhD |
| author_facet | Mahboob ur Rehman, PhD Omar A. Zeidan, PhD Twyla Willoughby, PhD Sanford L. Meeks, PhD Patrick Kelly, MD Kevin Erhart, PhD |
| author_sort | Mahboob ur Rehman, PhD |
| collection | DOAJ |
| description | Purpose: To present quantitative dosimetric evaluations of five proton pencil beam spot placement techniques.
Materials and Methods: The spot placement techniques that were investigated include two grid-based (rectilinear grid and hexagonal grid, both commonly available in commercial planning systems) and three boundary-contoured (concentric contours, hybrid, and optimized) techniques. Treatment plans were created for two different target volumes, one spherical and one conical. An optimal set of planning parameters was defined for all treatment plans and the impact of spot placement techniques on the plan quality was evaluated in terms of lateral/distal dose falloff, normal tissue sparing, conformity and homogeneity of dose distributions, as well as total number of spots used.
Results: The results of this work highlight that for grid-based spot placement techniques, the dose conformity is dependent on target cross-sectional shape perpendicular to beam direction, which changes for each energy layer. This variable conformity problem is mitigated by using boundary contoured spot placement techniques. However, in the case of concentric contours, the conformity is improved but at the cost of decreased homogeneity inside the target. Hybrid and optimized spot placement techniques, which use contoured spots at the boundary and gridlike interior spot patterns, provide more uniform dose distributions inside the target volume while maintaining the improved dose conformity. The optimized spot placement technique improved target coverage, homogeneity of dose, and minimal number of spots. The dependence of these results on spot size is also presented for both target shapes.
Conclusion: This work illustrates that boundary-contoured spot placement techniques offer marked improvement in dosimetry metrics when compared to commercially available grid-based techniques for a range of proton scanned beam spot sizes. |
| first_indexed | 2024-04-24T08:22:06Z |
| format | Article |
| id | doaj.art-ff38ee783d69431cb00772544be73478 |
| institution | Directory Open Access Journal |
| issn | 2331-5180 |
| language | English |
| last_indexed | 2024-04-24T08:22:06Z |
| publishDate | 2022-01-01 |
| publisher | Particle Therapy Co-operative Group |
| record_format | Article |
| series | International Journal of Particle Therapy |
| spelling | doaj.art-ff38ee783d69431cb00772544be734782024-04-17T00:59:02ZengParticle Therapy Co-operative GroupInternational Journal of Particle Therapy2331-51802022-01-0191546310.14338/IJPT-21-00022.1i2331-5180-9-1-54Dosimetric Comparison of Various Spot Placement Techniques in Proton Pencil Beam ScanningMahboob ur Rehman, PhD0Omar A. Zeidan, PhD1Twyla Willoughby, PhD2Sanford L. Meeks, PhD3Patrick Kelly, MD4Kevin Erhart, PhD51 University of Central Florida (UCF), Orlando, FL, USA2 Orlando Health Cancer Institute, Orlando, FL, USA2 Orlando Health Cancer Institute, Orlando, FL, USA2 Orlando Health Cancer Institute, Orlando, FL, USA2 Orlando Health Cancer Institute, Orlando, FL, USA3 .decimal LLC, Sanford, FL, USAPurpose: To present quantitative dosimetric evaluations of five proton pencil beam spot placement techniques. Materials and Methods: The spot placement techniques that were investigated include two grid-based (rectilinear grid and hexagonal grid, both commonly available in commercial planning systems) and three boundary-contoured (concentric contours, hybrid, and optimized) techniques. Treatment plans were created for two different target volumes, one spherical and one conical. An optimal set of planning parameters was defined for all treatment plans and the impact of spot placement techniques on the plan quality was evaluated in terms of lateral/distal dose falloff, normal tissue sparing, conformity and homogeneity of dose distributions, as well as total number of spots used. Results: The results of this work highlight that for grid-based spot placement techniques, the dose conformity is dependent on target cross-sectional shape perpendicular to beam direction, which changes for each energy layer. This variable conformity problem is mitigated by using boundary contoured spot placement techniques. However, in the case of concentric contours, the conformity is improved but at the cost of decreased homogeneity inside the target. Hybrid and optimized spot placement techniques, which use contoured spots at the boundary and gridlike interior spot patterns, provide more uniform dose distributions inside the target volume while maintaining the improved dose conformity. The optimized spot placement technique improved target coverage, homogeneity of dose, and minimal number of spots. The dependence of these results on spot size is also presented for both target shapes. Conclusion: This work illustrates that boundary-contoured spot placement techniques offer marked improvement in dosimetry metrics when compared to commercially available grid-based techniques for a range of proton scanned beam spot sizes.https://theijpt.org/doi/pdf/10.14338/IJPT-21-00022.1proton therapyspot placement in proton pencil beam scanning |
| spellingShingle | Mahboob ur Rehman, PhD Omar A. Zeidan, PhD Twyla Willoughby, PhD Sanford L. Meeks, PhD Patrick Kelly, MD Kevin Erhart, PhD Dosimetric Comparison of Various Spot Placement Techniques in Proton Pencil Beam Scanning International Journal of Particle Therapy proton therapy spot placement in proton pencil beam scanning |
| title | Dosimetric Comparison of Various Spot Placement Techniques in Proton Pencil Beam Scanning |
| title_full | Dosimetric Comparison of Various Spot Placement Techniques in Proton Pencil Beam Scanning |
| title_fullStr | Dosimetric Comparison of Various Spot Placement Techniques in Proton Pencil Beam Scanning |
| title_full_unstemmed | Dosimetric Comparison of Various Spot Placement Techniques in Proton Pencil Beam Scanning |
| title_short | Dosimetric Comparison of Various Spot Placement Techniques in Proton Pencil Beam Scanning |
| title_sort | dosimetric comparison of various spot placement techniques in proton pencil beam scanning |
| topic | proton therapy spot placement in proton pencil beam scanning |
| url | https://theijpt.org/doi/pdf/10.14338/IJPT-21-00022.1 |
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