Development and Validation of a GEANT4 Radiation Transport Code for CT Dosimetry

Carver, D; Kost, Susan; Fernald, Michael J.; Lewis, Kenneth G.; Fraser, Nicholas D.; Pickens, David R.; Price, Ronald R.; Stabin, Michael G.

doi:10.1097/hp.0000000000000243

Cited by 5 publications

(11 citation statements)

References 27 publications

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“…We performed simulations of helical CT examinations using a Geant4-based Monte Carlo particle radiation transport code previously described [34] and briefly summarized here. Specific properties of the Philips Brilliance 64 scanner including the photon-energy spectrum, inherent and bowtie filtration, and geometry were incorporated into the simulation.…”

Section: Methodsmentioning

confidence: 99%

Patient-specific dose calculations for pediatric CT of the chest, abdomen and pelvis

et al. 2015

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Background Organ dose is essential for accurate estimates of patient dose from CT. Objective To determine organ doses from a broad range of pediatric patients undergoing diagnostic chest–abdomen–pelvis CT and investigate how these relate to patient size. Materials and methods We used a previously validated Monte Carlo simulation model of a Philips Brilliance 64 multi-detector CT scanner (Philips Healthcare, Best, The Netherlands) to calculate organ doses for 40 pediatric patients (M:F=21:19; range 0.6–17 years). Organ volumes and positions were determined from the images using standard segmentation techniques. Non-linear regression was performed to determine the relationship between volume CT dose index (CTDIvol)-normalized organ doses and abdominopelvic diameter. We then compared results with values obtained from independent studies. Results We found that CTDIvol-normalized organ dose correlated strongly with exponentially decreasing abdominopelvic diameter (R2>0.8 for most organs). A similar relationship was determined for effective dose when normalized by dose-length product (R2=0.95). Our results agreed with previous studies within 12% using similar scan parameters (i.e. bowtie filter size, beam collimation); however results varied up to 25% when compared to studies using different bowtie filters. Conclusion Our study determined that organ doses can be estimated from measurements of patient size, namely body diameter, and CTDIvol prior to CT examination. This information provides an improved method for patient dose estimation.

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Section: Methodsmentioning

confidence: 99%

Patient-specific dose calculations for pediatric CT of the chest, abdomen and pelvis

et al. 2015

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“…A subset of these is shown in Figure 1 for the 5-year-old phantom series. A program was developed to convert the phantom NURBS surfaces into voxelized phantoms for input into our GEANT4 simulation [13, 27]. Voxel size is a user-defined variable in this program, which was defined as 1.5×1.5×3.0 mm for our phantoms as an appropriate compromise between spatial resolution and computation time and resources.…”

Section: Methodsmentioning

confidence: 99%

“…A GEANT4-based Monte Carlo particle radiation transport code previously described in the literature [13] was used to perform simulations of helical CT examinations. CT scanner properties such as photon-energy spectrum, inherent and bow tie filtration, and geometry were modeled explicitly.…”

Section: Methodsmentioning

confidence: 99%

“…The CT scanner model also includes the effects of the body bow tie filter, which provides X-ray filtration across the transverse direction of each phantom. Detailed descriptions of the CT scanner properties modeled are provided in Carver et al [13]. Simulated CT 100-mm dose index (CTDI 100 ) values [42] were directly compared to the measured dose indices with overall average agreement within 6%.…”

Section: Methodsmentioning

confidence: 99%

“…Li et al [12] developed a model of a GE Healthcare LightSpeed VCT. In our previous work [13], we developed and validated a model of a Philips Brilliance 64-slice multidetector scanner (Philips Healthcare, Best, The Netherlands) used at the Monroe Carrell Jr. Children’s Hospital at Vanderbilt University. Doses calculated using Monte Carlo simulations are directly applicable to the particular scanner modeled, but some have suggested that doses may also be scanner-independent when normalized by CT dose index – volume (CTDI vol ) [14, 15].…”

Section: Introductionmentioning

confidence: 99%

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Realistic phantoms to characterize dosimetry in pediatric CT

et al. 2017

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Background The estimation of organ doses and effective doses for children receiving CT examinations is of high interest. Newer, more realistic anthropomorphic body models can provide information on individual organ doses and improved estimates of effective dose. Materials and methods Previously developed body models representing 50th-percentile individuals at reference ages (newborn, 1, 5, 10 and 15 years) were modified to represent 10th, 25th, 75th and 90th height percentiles for both genders and an expanded range of ages (3, 8 and 13 years). We calculated doses for 80 pediatric reference phantoms from simulated chest-abdomen-pelvis exams on a model of a Philips Brilliance 64 CT scanner. Individual organ and effective doses were normalized to dose-length product (DLP) and fit as a function of body diameter. Results We calculated organ and effective doses for 80 reference phantoms and plotted them against body diameter. The data were well fit with an exponential function. We found DLP-normalized organ dose to correlate strongly with body diameter (R2>0.95 for most organs). Similarly, we found a very strong correlation with body diameter for DLP-normalized effective dose (R2>0.99). Our results were compared to other studies and we found average agreement of approximately 10%. Conclusion We provide organ and effective doses for a total of 80 reference phantoms representing normal-stature children ranging in age and body size. This information will be valuable in replacing the types of vendor-reported doses available. These data will also permit the recording and tracking of individual patient doses. Moreover, this comprehensive dose database will facilitate patient matching and the ability to predict patient-individualized dose prior to examination.

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Characterization of an x-ray source with a partitioned diamond-tungsten target for electronic brachytherapy with 3D beam directionality

et al. 2019

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The Sculptura™ is a new high-dose-rate electronic brachytherapy system developed by Sensus Healthcare. By combining a steerable electron beam with a partitioned diamond-tungsten x-ray target, the x-ray source of the Sculptura™ is capable of producing highly anisotropic dose distributions, thus achieving true 3D beam directionality. This article reports the spectral and dosimetric characterization of the Sculptura™ x-ray source through a combination of measurements and Monte Carlo simulations for operating points between 50–100 kV. Excellent agreement (~5% discrepancy) between the simulations and measurements was obtained for in-air dose rate characterization. The validated simulations were then used to calculate the dose distribution in water. Dose rates of >2 cGy/min/μA can be produced at 100 kV, thus delivering 10 Gy in 1 min for typical operating conditions. The dose distributions are sharply peaked, with a full-width at half-maximum azimuth of about 100°.

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Development and Validation of a GEANT4 Radiation Transport Code for CT Dosimetry

Cited by 5 publications

References 27 publications

Patient-specific dose calculations for pediatric CT of the chest, abdomen and pelvis

Patient-specific dose calculations for pediatric CT of the chest, abdomen and pelvis

Realistic phantoms to characterize dosimetry in pediatric CT

Characterization of an x-ray source with a partitioned diamond-tungsten target for electronic brachytherapy with 3D beam directionality

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