Implementation of full/half bowtie filter models in a commercial treatment planning system for kilovoltage cone‐beam CT dose estimations

Kim, Sangroh; Alaei, Parham

doi:10.1120/jacmp.v17i2.5988

Cited by 5 publications

(4 citation statements)

References 15 publications

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“…Furthermore, the choice of the protocol influences the dose distribution in the field‐of‐view region . Analytical models to calculate the CBCT dose are available but they lack the ability to calculate the dose outside the field‐of‐view …”

Section: Discussionmentioning

confidence: 99%

Whole‐body dose equivalent including neutrons is similar for 6 MV and 15 MV IMRT, VMAT, and 3D conformal radiotherapy

Hauri

Schneider

2019

J Applied Clin Med Phys

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Purpose This study investigates the difference in whole‐body dose equivalent between 6 and 15 MV image‐guided radiotherapy (IGRT) for the treatment of a rhabdomyosarcoma in the prostate. Methods A previously developed model for stray radiation of the primary beam was improved and used to calculate the photon dose and photon energy in the out‐of‐field region for a radiotherapy patient. The dose calculated by the treatment planning system was fused with the model‐calculated out‐of‐field dose, resulting in a whole‐body photon dose distribution. The peripheral neutron dose equivalent was calculated using an analytical model from the literature. A daily cone beam CT dose was added to the neutron and photon dose equivalents. The calculated 3D dose distributions were compared to independent measurements conducted with thermoluminescence dosimeters and an anthropomorphic phantom. The dose contributions from the IGRT treatments of three different techniques applied with two nominal X‐ray energies were compared using dose equivalent volume histograms (DEVHs). Results The calculated and measured out‐of‐field whole‐body dose equivalents for the IGRT treatments agreed within (9 ± 10) % (mean and type A SD). The neutron dose equivalent was a minor contribution to the total out‐of‐field dose up to 50 cm from the isocenter. Further from the isocenter, head leakage was dominating inside the patient body, whereas the neutron dose equivalent contribution was important close to the surface. There were small differences between the whole‐body DEVHs of the 6 and 15 MV treatments applied with the same technique, although the single scatter contributions showed large differences. Independent of the beam energy, the out‐of‐field dose of the volumetric‐modulated arc therapy (VMAT) treatment was significantly lower than the dynamic intensity‐modulated radiation therapy (IMRT) treatment. Conclusion The calculated whole‐body dose helped to understand the importance of the dose contributions in different areas of the patient. Regarding radiation protection of the patient for IGRT treatments, the choice of beam energy is not important, whereas the treatment technique has a large influence on the out‐of‐field dose. If the patient is treated with intensity‐modulated beams, VMAT should be used instead of dynamic IMRT in terms of radiation protection of the patient. In general, the developed models for photon and neutron dose equivalent calculation can be used for any patient geometry, tumor location, and linear accelerator.

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Section: Discussionmentioning

confidence: 99%

Whole‐body dose equivalent including neutrons is similar for 6 MV and 15 MV IMRT, VMAT, and 3D conformal radiotherapy

Hauri

Schneider

2019

J Applied Clin Med Phys

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“…In reference 51, Alaei et al used a “wedge” to mimic the isodose tilt of a half fan/half‐bow tie imaging beam in the treatment planning system. Further work in this area has demonstrated that this could also be achieved by inserting a compensator in the beam . The same commercial TPS has also been used to model kV beams from Elekta XVI and Siemens kVision imaging systems .…”

Section: Dose Calculation Algorithms For Kv and MV Imaging Dosementioning

confidence: 99%

Image guidance doses delivered during radiotherapy: Quantification, management, and reduction: Report of the AAPM Therapy Physics Committee Task Group 180

et al. 2018

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“…Considerable effort is required to shorten the scan time and decrease the imaging dose for patients. Previous studies investigated the changes in CBCT images by FOV and patient size using CT number values [14] and evaluated the exposure dose and image quality for different CBCT scan modes [15] . Both these studies used the Catphan 504 phantom (The Phantom Laboratory, Salem, NY, USA) and solid water phantom (Gammex-RMI, Middleton, WI, USA) which are both applicable to CBCT quality assurance (QA).…”

Section: Introductionmentioning

confidence: 99%

Usability assessment of cone beam computed tomography with a full-fan mode bowtie filter compared to that with a half-fan mode bowtie filter

2021

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Background:In intensity modulated radiation therapy, cone beam computed tomography (CT) has been used to evaluate patients prior to treatment. This study conducted a comparative evaluation of the image reconstruction ability of the clinically used half-fan bowtie filter and the full-fan bowtie filter. Materals and Methods: A CT simulation marker was inserted inside a human phantom, and the pelvic region, a large field-of-view region, was scanned by moving the isocenter along the x-axis ±1-5 cm with the full-fan mode. Furthermore, image verification was conducted based on the planning CT image and bone to confirm the setup correction value. The obtained value was then compared with that from the clinically used half-fan scan. Results:The evaluation of the reconstructed image (from the isocenter to the marker) after setting the median line did not show a significant difference with respect to the image obtained using the half-fan scan. Planning CT images and setup errors were compared in three directions, and the results showed that each mean value was within the margin of error (±3 mm). The 3D vector value was determined to be within 0-2.45 mm, and the comparison of the value obtained from the half-fan scan showed no statistically significant result. Conclusion:The application of a phantom study to actual patients in the future will reduce the error caused by movement during the treatment due to the short scan time and will reduce the imaging dose for patients during setup error confirmation and correction.

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Implementation of full/half bowtie filter models in a commercial treatment planning system for kilovoltage cone‐beam CT dose estimations

Cited by 5 publications

References 15 publications

Whole‐body dose equivalent including neutrons is similar for 6 MV and 15 MV IMRT, VMAT, and 3D conformal radiotherapy

Whole‐body dose equivalent including neutrons is similar for 6 MV and 15 MV IMRT, VMAT, and 3D conformal radiotherapy

Image guidance doses delivered during radiotherapy: Quantification, management, and reduction: Report of the AAPM Therapy Physics Committee Task Group 180

Usability assessment of cone beam computed tomography with a full-fan mode bowtie filter compared to that with a half-fan mode bowtie filter

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