Dose calculation and treatment plan optimization including imaging dose from kilovoltage cone beam computed tomography

Alaei, Parham; Spezi, Emiliano; Reynolds, Margaret

doi:10.3109/0284186x.2013.875626

Cited by 25 publications

(29 citation statements)

References 25 publications

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“…In this case, it may be warranted to include the imaging dose in the planning process. It has been shown that this approach is feasible and that including imaging dose during plan optimization reduces the overall dose delivered to patient [54,78,88]. This, however, is not a trivial task and requires either use of Monte Carlo or commissioning of imaging beams in treatment planning systems.…”

Section: Discussionmentioning

confidence: 98%

“…Patient size does play a role in the imaging dose from kV CBCT with larger patients receiving lower dose to the isocenter and internal organs, but not to the skin [78]. This can be described as a correlation between body mass index (BMI) and organ doses, especially in pelvic imaging.…”

Section: Kilovoltage Cbct System Beams Detailsmentioning

confidence: 97%

“…This can be described as a correlation between body mass index (BMI) and organ doses, especially in pelvic imaging. This correlation is weak in the case of Megavoltage imaging [74] but stronger for kilovoltage ones [78]. The correlation between patient size and imaging dose translates into increased dose to pediatric patients when adult imaging techniques are employed.…”

Section: Kilovoltage Cbct System Beams Detailsmentioning

confidence: 98%

“…Ding [49] Varian OBI Single beam, half-fan, half-bowtie Beam data collection, MC simulation and verification Chow [58] Elekta XVI Single cassette, no filter Beam data collection, MC simulation and verification Spezi [50] Elekta XVI Multiple cassettes, no filter Beam data collection, MC simulation and verification Downes [51] Elekta XVI Multiple cassettes, bowtie Beam data collection, MC simulation and verification Ding [48] Varian OBI Multiple beams/filters Beam data collection, MC simulation and verification Alaei [52] Varian OBI Single beam, half-fan, half-bowtie Modeling in TPS and verification Deng [59] Varian OBI Half-fan, half-bowtie & Full-fan, full-bowtie Beam data collection, MC simulation and verification Deng [60] Varian OBI Half-fan, half-bowtie & Full-fan, full-bowtie Beam data collection, MC simulation and verification Alaei [53] Elekta XVI Multiple cassettes, no filter and bowtie Modeling in TPS and verification Dzierma [57] Siemens kView Two beam qualities Beam data collection, modeling in TPS and verification Megavoltage CBCT Flynn [45] Siemens IBL IBL beam Beam data collection, modeling in TPS and verification (organ doses) computation [52,53,57,78]. Fig.…”

Section: Kilovoltage Cbct System Beams Detailsmentioning

confidence: 99%

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Imaging dose from cone beam computed tomography in radiation therapy

2015

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Imaging dose in radiation therapy has traditionally been ignored due to its low magnitude and frequency in comparison to therapeutic dose used to treat patients. The advent of modern, volumetric, imaging modalities, often as an integral part of linear accelerators, has facilitated the implementation of image-guided radiation therapy (IGRT), which is often accomplished by daily imaging of patients. Daily imaging results in additional dose delivered to patient that warrants new attention be given to imaging dose. This review summarizes the imaging dose delivered to patients as the result of cone beam computed tomography (CBCT) imaging performed in radiation therapy using current methods and equipment. This review also summarizes methods to calculate the imaging dose, including the use of Monte Carlo (MC) and treatment planning systems (TPS). Peripheral dose from CBCT imaging, dose reduction methods, the use of effective dose in describing imaging dose, and the measurement of CT dose index (CTDI) in CBCT systems are also reviewed.

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Section: Discussionmentioning

confidence: 98%

Section: Kilovoltage Cbct System Beams Detailsmentioning

confidence: 97%

Section: Kilovoltage Cbct System Beams Detailsmentioning

confidence: 98%

Section: Kilovoltage Cbct System Beams Detailsmentioning

confidence: 99%

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Imaging dose from cone beam computed tomography in radiation therapy

2015

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“…Alaei et al [20] showed that the dose from daily kV CBCT results in an additional isocenter dose of the order of 30–40 mGy for 35 fractions head and neck and 230–240 mGy for 25 fractions pelvis irradiation. The authors used the commissioning of kV CBCT beams in the TPS primarily to include the imaging dose in the treatment plan prior to optimization.…”

Section: Discussionmentioning

confidence: 99%

Influence of daily imaging on plan quality and normal tissue toxicity for prostate cancer radiotherapy

et al. 2017

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BackgroundModern radiotherapy offers various possibilities for image guided verification of patient positioning. Different clinically relevant IGRT (image guided radiotherapy) scenarios were considered with regard to their influence on dosimetric plan quality and normal tissue complication probability (NTCP).MethodsThis study is based on treatment plans of 50 prostate patients. We evaluate the clinically performed IGRT and simulate the influence of different daily IGRT scenarios on plan quality. Imaging doses of planar and cone-beam-CT (CBCT) images for three different energies (6 MV, 1 MV and 121 kV) were added to the treatment plans. The plan quality of the different scenarios was assessed by a visual inspection of the dose distribution and dose-volume-histogram (DVH) and a statistical analysis of DVH criteria. In addition, an assessment of the normal tissue complication probability was performed.ResultsDaily 1MV-CBCTs result in undesirable high dose regions in the target volume. The DVH shows that the scenarios with actual imaging performed, daily kV-CBCT and daily 6MV imaging (1x CBCT, 4x planar images per week) do not differ exceedingly from the original plan; especially imaging with daily kV-CBCT has little influence to the sparing of organs at risk. In contrast, daily 1MV- CBCT entails an additional dose of up to two fraction doses. Due to the additional dose amount some DVH constraints for plan acceptability could no longer be satisfied, especially for the daily 1MV-CBCT scenario. This scenario also shows increased NTCP for the rectum.ConclusionDaily kV-CBCT has negligible influence on plan quality and is commendable for the clinical routine. If no kV-modality is available, a daily IGRT scenario with one CBCT per week and planar axial images on the other days should be preferred over daily MV-CBCT.

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How low can you go? A CBCT dose reduction study

Olch

Alaei

2021

J Applied Clin Med Phys

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Purpose Cone beam computed tomography (CBCT) is often used for patient setup based solely on bony anatomy. The goal of this work was to evaluate whether CBCT dose can be lowered to the level of kV image pair doses when used for bony anatomy‐based IGRT without compromising positioning accuracy. Methods An anthropomorphic phantom was CT scanned in the head, head and neck, chest, and pelvis regions and setup on the linear accelerator couch with the isocenter near the planned location. Cone beam computed tomographies were performed with the standard “full dose” protocol supplied by the linac vendor. With sequentially lowering the dose, three‐dimensional (3D) matching was performed for each without shifting the couch. The standard kV image pair protocol for each site was also used to image the phantoms. For all studies, six degrees of freedom was included in the 2D or 3D matching to the extent they could be employed. Imaging doses were determined in air at isocenter following the TG‐61 formalism. Results Cone beam computed tomography dose was reduced by 81–98% of the standard CBCT protocol to nearly that of the standard kV image pair dose for each site. Relative to the standard CBCT shift values, translational shifts were within 0.3 and 1.6 mm for all sites, for the reduced dose CBCT and kV image pair, respectively. Rotational shifts were within 0.2 degree and 0.7 degrees for all sites, for the reduced dose CBCTs and kV image pair, respectively. Conclusion For bony anatomy‐based image guidance, CBCT dose can be reduced to a value similar to that of a kV image pair with similar or better patient positioning accuracy than kV image pair alignment. Where rotations are important to correct, CBCT will be superior to orthogonal kV imaging without significantly increased imaging dose. This is especially important for image guidance for pediatric patient treatments.

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Dose calculation and treatment plan optimization including imaging dose from kilovoltage cone beam computed tomography

Cited by 25 publications

References 25 publications

Imaging dose from cone beam computed tomography in radiation therapy

Imaging dose from cone beam computed tomography in radiation therapy

Influence of daily imaging on plan quality and normal tissue toxicity for prostate cancer radiotherapy

How low can you go? A CBCT dose reduction study

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