Proposal and Evaluation of a Practical CBCT Dose Optimization Method
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arXiv
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| Main Authors: | , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866910811056766976 |
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| author | Gros, S. Bian, J. Jackson, J. Delafuente, M. Kang, H. Small Jr, W. Mahesh, M. |
| author_facet | Gros, S. Bian, J. Jackson, J. Delafuente, M. Kang, H. Small Jr, W. Mahesh, M. |
| contents | Objective: To propose a CBCT dose optimization method using readily available measurement equipment in radiation oncology departments.
Approach: A 0.6cc air kerma (Kair) calibrated Farmer chamber measured Kair at isocenter for five default CBCT protocols (HEAD, PELVIS, LARGE PELVIS, THORAX, SPOTLIGHT) on a Varian TrueBeam linac. Imaging parameters were modified to reduce cumulative exposure by reducing projections (by 25%, 50%, 75%) in FDK reconstruction, or lowering single frame exposure by 25%, 50%, 70 to 75%. Cone Beam Dose Index (CBDI) and weighted CBDI (CBDI_w) were measured in CTDI phantoms to correlate with Kair. Image quality was assessed quantitatively (HU linearity, uniformity, low-contrast visibility, high-contrast resolution, spatial integrity) using Catphan604, and qualitatively via anthropomorphic phantoms.
Results: A linear relationship between Kair, CTDI, and CBDI_w was established. High-contrast resolution and spatial integrity were unaffected by dose reduction (R < 0.5), while low-contrast visibility strongly correlated with exposure (R > 0.75). HU uniformity and linearity remained stable (<40 HU deviation), except for LARGE PELVIS at <50% single-frame exposure. 80 to 50% dose reduction retained clinically acceptable image quality with minimal artifacts or noise.
Significance: CBCT protocols on TrueBeam linacs were optimized for dose reduction. The method enables easy implementation by radiotherapy physicists without diagnostic physics equipment or expertise. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2502_01509 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Proposal and Evaluation of a Practical CBCT Dose Optimization Method Gros, S. Bian, J. Jackson, J. Delafuente, M. Kang, H. Small Jr, W. Mahesh, M. Medical Physics Objective: To propose a CBCT dose optimization method using readily available measurement equipment in radiation oncology departments. Approach: A 0.6cc air kerma (Kair) calibrated Farmer chamber measured Kair at isocenter for five default CBCT protocols (HEAD, PELVIS, LARGE PELVIS, THORAX, SPOTLIGHT) on a Varian TrueBeam linac. Imaging parameters were modified to reduce cumulative exposure by reducing projections (by 25%, 50%, 75%) in FDK reconstruction, or lowering single frame exposure by 25%, 50%, 70 to 75%. Cone Beam Dose Index (CBDI) and weighted CBDI (CBDI_w) were measured in CTDI phantoms to correlate with Kair. Image quality was assessed quantitatively (HU linearity, uniformity, low-contrast visibility, high-contrast resolution, spatial integrity) using Catphan604, and qualitatively via anthropomorphic phantoms. Results: A linear relationship between Kair, CTDI, and CBDI_w was established. High-contrast resolution and spatial integrity were unaffected by dose reduction (R < 0.5), while low-contrast visibility strongly correlated with exposure (R > 0.75). HU uniformity and linearity remained stable (<40 HU deviation), except for LARGE PELVIS at <50% single-frame exposure. 80 to 50% dose reduction retained clinically acceptable image quality with minimal artifacts or noise. Significance: CBCT protocols on TrueBeam linacs were optimized for dose reduction. The method enables easy implementation by radiotherapy physicists without diagnostic physics equipment or expertise. |
| title | Proposal and Evaluation of a Practical CBCT Dose Optimization Method |
| topic | Medical Physics |
| url | https://arxiv.org/abs/2502.01509 |