Assessment of the dosimetric accuracies of CATPhan 504 and CIRS 062 using kV-CBCT for performing direct calculations

Annkah, J.; Rosenberg, Ivan; Hindocha, N.; Moinuddin, S.; Ricketts, K; Adeyemi, Abiodun; Royle, G.

doi:10.4103/0971-6203.139001

Cited by 7 publications

(13 citation statements)

References 7 publications

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“…In many studies, customised protocols were chosen [37,40,107,41,47,48,55,58,66,75,104], adding extra variables to be considered when comparing the techniques adopted to perform CBCT dose calculation. Therefore, site-specific protocols for each machine model cannot be specified in this review for an optimal CBCT dose calculation.…”

Section: Physical Limitationsmentioning

confidence: 99%

A review of dose calculation approaches with cone beam CT in photon and proton therapy

2020

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Background and purpose: The use of cone beam computed tomography (CBCT) for performing dose calculations in radiation therapy has been widely investigated as it could provide a quantitative analysis of the dosimetric impact of changes in patients during the treatment. The aim of this review was to classify different techniques adopted to perform CBCT dose calculation and to report their dosimetric accuracy with respect to the metrics used. Methods and materials: A literature search was carried out in PubMed and ScienceDirect databases, based upon the following keywords: "cone beam computed tomography", "CBCT", "cone beam CT", "dose calculation", "accuracy". Sixty-nine peer-reviewed relevant articles were included in this review: thirty-one patient studies, fifteen phantom studies and twenty-three patient & phantom studies. Most studies were found to have focused on head and neck, lung and prostate cancers. Results: The techniques adopted to perform CBCT dose calculation have been grouped in six categories labelled as (1) pCT calibration, (2) CBCT calibration, (3) HU override, (4) Deformable image registration, (5) Dose deformation, and (6) Combined techniques. Differences between CBCT dose and reference dose were reported both for target volumes and OARs. Conclusions: A comparison among the available techniques for CBCT dose calculations is challenging as many variables are involved. Therefore, a set of reporting standards is recommended to enable meaningful comparisons among different studies. The accuracy of the results was strongly dependent on the image quality, regardless of the methods used, highlighting the need for dose validation and quality assurance standards. the results are highly variable due to different devices, protocols, datasets, metrics of comparison, treatment sites and treatment planning systems (TPS) being reported in the different studies. This wide variety in the dose reconstruction methodologies and reporting methods used in this expanding field has identified a need to review the current status of the field. This work considers the current

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Section: Physical Limitationsmentioning

confidence: 99%

A review of dose calculation approaches with cone beam CT in photon and proton therapy

2020

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“…In this study, a self-developed tool, the cone-beam CT imaging toolkit (CITK), was used for CBCT image scatter correction. This tool considers the interaction between the particles and the substance in the Monte Carlo (MC) simulation and separates the scattering components from the original CBCT projection files ( 19 , 27 ), realizing CBCT image scattering correction.…”

Section: Methodsmentioning

confidence: 99%

“…They found that the computed tomography (CT) value [in Hounsfield units (HU)] of CBCT images was significantly different from that of planning CT (pCT) images. Annkah et al ( 19 ) found that the maximum dose difference reached 14% in a phantom. Therefore, establishing appropriate HU-relative electron density (HU-RED) calibration for CBCT images is critical for clinical dose calculations ( 17 - 19 ).…”

Section: Introductionmentioning

confidence: 99%

“…Annkah et al ( 19 ) found that the maximum dose difference reached 14% in a phantom. Therefore, establishing appropriate HU-relative electron density (HU-RED) calibration for CBCT images is critical for clinical dose calculations ( 17 - 19 ). Richter’s ( 20 ) study showed that the difference in the dose calculation was reduced after the establishment of an HU-RED calibration curve for different CBCT scanning conditions, but the reduction was insufficient to meet clinical needs.…”

Section: Introductionmentioning

confidence: 99%

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Feasibility evaluation of kilovoltage cone-beam computed tomography dose calculation following scatter correction: investigations of phantom and representative tumor sites

Meng¹,

Qiu²,

Zhang³

et al. 2021

Transl Cancer Res TCR

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Background: To study the feasibility of kilovoltage cone-beam computed tomography (KV-CBCT) dose calculation following scatter correction.Methods: CIRS 062 and Catphan 504 phantoms were used in this study, and 40 randomly selected subjects representing a variety of cases (ten head cancer cases, ten chest cancer cases, ten abdominal cancer cases and ten pelvic cavity cancer cases) were enrolled. We developed in-house software called the cone-beam CT imaging toolkit (CITK) to improve the quality of CBCT images. We first aligned each planning computed tomography (pCT) image with the corresponding CBCT image using rigid registration after scatter correction. Hounsfield unit-relative electron density (HU-RED) calibration was applied to the CBCT images. The pCT plan was then recalculated on CBCT images. Finally, the dosimetric differences between the two plans were evaluated. The dosimetric parameters included the D98, D2, Dmean, conformity index (CI), homogeneity index (HI) and other organ at risk (OAR) dose parameters of the planning target volume (PTV). The dose distribution index (DDI) and the gamma index were also assessed. Paired Student's t-tests or Wilcoxon rank tests were used to evaluate differences. P<0.05 was considered significant.Results: In the phantom and patient cases, the average dosimetric difference was less than 1% in the PTV and OARs. There was no significant difference in the CI or HI between the two plans. The gamma pass rate of 2%/2 mm was greater than 95% in both plans. There was a significant difference in the DDI between the two plans in the chest group but not in the other groups. Conclusions:The results suggest that CBCT has high accuracy in dose calculation via scatter correction and HU-RED calibration.

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“…Note that X-ray photons are mainly attenuated by interactions with atomic shell electrons, the tissue-specific attenuation coefficient is strongly correlated to the local electron density ρ е which in turn is correlated with the local tissue mass density ρ m . Thus since H (μ tissue ) ≈ ρ m , commonly the latter is deduced from measured relative attenuation coefficients assuming a piece-wise linear relation according to where ρ(H) is measured in CGS units g • cm -3 [17].…”

Section: Imaging Proceduresmentioning

confidence: 99%

Estimation of [177Lu]PSMA-617 tumor uptake based on voxel-wise 3D Monte Carlo tumor dosimetry in patients with metastasized castration resistant prostate cancer

et al. 2020

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Objective Patients with advanced prostate cancer are suitable candidates for [177Lu]PSMA-617 therapy. Integrated SPECT/CT systems have the potential to improve the accuracy of patient-specific tumor dosimetry. We present a novel patient-specific Monte Carlo based voxel-wise dosimetry approach to determine organ and total tumor doses (TTD). Methods 13 patients with histologically confirmed metastasized castration-resistant prostate cancer were treated with a total of 18 cycles of [177Lu]PSMA-617 therapy. In each patient, dosimetry was performed after the first cycle of [177Lu]PSMA-617 therapy. Regions of interest were defined manually on the SPECT/CT images for the kidneys, spleen and all 295 PSMA-positive tumor lesions in the field of view. The absorbed dose to normal organs and to all tumor lesions were calculated by a three dimensional dosimetry method based on Monte Carlo Simulations. Results The average dose values yielded the following results: 2.59 ± 0.63 Gy (1.67–3.92 Gy) for the kidneys, 0.79 ± 0.46 Gy (0.31–1.90 Gy) for the spleen and 11.00 ± 11.97 Gy (1.28–49.10 Gy) for all tracer-positive tumor lesions. A trend towards higher TTD was observed in patients with Gleason Scores > 8 compared to Gleason Scores ≤ 8 and in lymph node metastases compared to bone metastases. A significant correlation was determined between the serum-PSA level before RLT and the TTD (r = –0.57, p < 0.05), as well as between the TTD with the percentage change of serum-PSA levels before and after therapy was observed (r = –0.57, p < 0.05). Patients with higher total tumor volumes of PSMA-positive lesions demonstrated significantly lower kidney average dose values (r = –0.58, p < 0.05). Conclusion The presented novel Monte Carlo based voxel-wise dosimetry calculates a patient specific whole-body dose distribution, thus taking into account individual anatomies and tissue compositions showing promising results for the estimation of radiation doses of normal organs and PSMA-positive tumor lesions.

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Assessment of the dosimetric accuracies of CATPhan 504 and CIRS 062 using kV-CBCT for performing direct calculations

Cited by 7 publications

References 7 publications

A review of dose calculation approaches with cone beam CT in photon and proton therapy

A review of dose calculation approaches with cone beam CT in photon and proton therapy

Feasibility evaluation of kilovoltage cone-beam computed tomography dose calculation following scatter correction: investigations of phantom and representative tumor sites

Estimation of [177Lu]PSMA-617 tumor uptake based on voxel-wise 3D Monte Carlo tumor dosimetry in patients with metastasized castration resistant prostate cancer

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