Volume-of-interest cone-beam CT using a 2.35 MV beam generated with a carbon target

Robar, James L.; Parsons, David; Berman, Anna A.; MacDonald, Alison

doi:10.1118/1.4728977

Cited by 9 publications

(22 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The previously described imaging paradigm by Robar et al 5 was used within this work, in which the VOI was defined at the time of treatment planning using the Eclipse (Varian Medical Systems, Inc., Palo Alto, CA) treatment planning F. 3.…”

Section: B Volume-of-interest Imaging Protocolmentioning

confidence: 99%

“…11 Several preprocessing steps were added to the algorithm to account for the truncation artifacts associated when reconstructing VOI projections. Several authors have reported various methods to correct for these artifacts, including, for example, using DRRs to fill the region outside the VOI, 5 acquiring two sets of projections, a VOI and either a reduced exposure or a sparse full-field projection, 4,12 pi-line reconstruction, 13 or extrapolating the boundary of the VOI. 5,14 Within this work, the exponential extrapolation was utilized as defined previously by Robar et al 5 This method was chosen as it is computationally simple, it only requires a truncated projection and produces equivalent reconstructed images as DRR filling.…”

Section: B Volume-of-interest Imaging Protocolmentioning

confidence: 99%

“…Several authors have reported various methods to correct for these artifacts, including, for example, using DRRs to fill the region outside the VOI, 5 acquiring two sets of projections, a VOI and either a reduced exposure or a sparse full-field projection, 4,12 pi-line reconstruction, 13 or extrapolating the boundary of the VOI. 5,14 Within this work, the exponential extrapolation was utilized as defined previously by Robar et al 5 This method was chosen as it is computationally simple, it only requires a truncated projection and produces equivalent reconstructed images as DRR filling. 5 Previously, 5 thresholding techniques were used to determine the location of the VOI boundary; however, this proved to be difficult when translating this approach from a megavoltage low-Z imaging beam to a dedicated kilovoltage image system.…”

Section: B Volume-of-interest Imaging Protocolmentioning

confidence: 99%

“…5,14 Within this work, the exponential extrapolation was utilized as defined previously by Robar et al 5 This method was chosen as it is computationally simple, it only requires a truncated projection and produces equivalent reconstructed images as DRR filling. 5 Previously, 5 thresholding techniques were used to determine the location of the VOI boundary; however, this proved to be difficult when translating this approach from a megavoltage low-Z imaging beam to a dedicated kilovoltage image system. This deficiency was due to appreciable transmission through the lap joints in some projections.…”

Section: B Volume-of-interest Imaging Protocolmentioning

confidence: 99%

“…Robar et al 5 developed a dynamic collimation VOI CBCT method using the multileaf collimator (MLC) in a linear accelerator with a 2.35 MeV electron beam incident on a carbon target. Tracking of the VOI was analogous to dynamic conformal arc therapy used commonly in radiation therapy.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

An investigation of kV CBCT image quality and dose reduction for volume‐of‐interest imaging using dynamic collimation

Parsons

Robar

2015

Medical Physics

Self Cite

View full text Add to dashboard Cite

show abstract

Section: B Volume-of-interest Imaging Protocolmentioning

confidence: 99%

Section: B Volume-of-interest Imaging Protocolmentioning

confidence: 99%

Section: B Volume-of-interest Imaging Protocolmentioning

confidence: 99%

Section: B Volume-of-interest Imaging Protocolmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

An investigation of kV CBCT image quality and dose reduction for volume‐of‐interest imaging using dynamic collimation

Parsons

Robar

2015

Medical Physics

Self Cite

View full text Add to dashboard Cite

show abstract

Region‐of‐interest intra‐arc MV imaging to facilitate sub‐mm positional accuracy with minimal imaging dose during treatment deliveries of small cranial lesions

Church

Parsons

Syme

2022

J Applied Clin Med Phys

Self Cite

View full text Add to dashboard Cite

Purpose To automate the generation of region‐of‐interest (ROI) apertures for use with megavoltage imaging for online positional corrections during cranial stereotactic radiosurgery. Materials and methods Digitally reconstructed radiographs (DRRs) were created for a 3D‐printed skull phantom at 5 degree gantry angle increments for a three‐arc beam arrangement. At each angle, 3000 random rectangular apertures were generated, and 100 shifts on a grid were applied to the anatomy within the frame. For all shifts, the mutual information (MI) between the shifted and unshifted DRR was calculated to derive an average MI gradient. The top 10% of apertures that minimized registration errors were overlaid and discretely thresholded to generate imaging plans. Imaging was acquired with the skull while implementing simulated patient motion on a linac. Control point‐specific couch motions were derived to align the skull to its planned positioning. Results Apertures with a range of repositioning errors less than 0.1 mm possessed a 42% larger average MI gradient when compared with apertures with a range greater than 1 mm. Dose calculations with Monte Carlo exhibited an 84% reduction in the dose received by 50% of the skull with the 50% thresholded plan when compared to a constant 22 × 22 cm2 imaging plan. For all different imaging plans (with and without motion), the calculated median 3D‐errors with respect to the tracking of a metal‐BB fiducial positioned at isocenter in the skull were sub‐mm except for the 80% thresholded plan. Conclusions Sub‐mm positional errors are achievable with couch motions derived from control point–specific ROI imaging. Smaller apertures that conform to an anatomical ROI can be utilized to minimize the imaging dose incurred at the expense of larger errors.

show abstract

Report of AAPM Task Group 235 Radiochromic Film Dosimetry: An Update to TG‐55

et al. 2020

View full text Add to dashboard Cite

The use of radiochromic film (RCF) dosimetry in radiation therapy is extensive due to its high level of achievable accuracy for a wide range of dose values and its suitability under a variety of measurement conditions. However, since the publication of the 1998 AAPM Task Group 55, Report No. 63 on RCF dosimetry, the chemistry, composition, and readout systems for RCFs have evolved steadily. There are several challenges in using the new RCFs, readout systems and validation of the results depending on their applications. Accurate RCF dosimetry requires understanding of RCF selection, handling and calibration methods, calibration curves, dose conversion methods, correction methodologies as well as selection, operation and quality assurance (QA) programs of the readout systems. Acquiring this level of knowledge is not straight forward, even for some experienced users. This Task Group report addresses these issues and provides a basic understanding of available RCF models, dosimetric characteristics and properties, advantages and limitations, configurations, and overall elemental compositions of the RCFs that have changed over the past 20 yr. In addition, this report provides specific guidelines for data processing and analysis schemes and correction methodologies for clinical applications in radiation therapy.

show abstract

Volume-of-interest cone-beam CT using a 2.35 MV beam generated with a carbon target

Cited by 9 publications

References 21 publications

An investigation of kV CBCT image quality and dose reduction for volume‐of‐interest imaging using dynamic collimation

An investigation of kV CBCT image quality and dose reduction for volume‐of‐interest imaging using dynamic collimation

Region‐of‐interest intra‐arc MV imaging to facilitate sub‐mm positional accuracy with minimal imaging dose during treatment deliveries of small cranial lesions

Report of AAPM Task Group 235 Radiochromic Film Dosimetry: An Update to TG‐55

Contact Info

Product

Resources

About