A graphic user interface toolkit for specification, report and comparison of dose–response relations and treatment plans using the biologically effective uniform dose

J Applied Clin Med Phys

Papanikolaou

et al. 2014

Self Cite

Currently, radiotherapy treatment plan acceptance is based primarily on dosimetric performance measures. However, use of radiobiological analysis to assess benefit in terms of tumor control and harm in terms of injury to normal tissues can be advantageous. For pediatric craniospinal axis irradiation (CSI) patients, in particular, knowing the technique that will optimize the probabilities of benefit versus injury can lead to better long‐term outcomes. Twenty‐four CSI pediatric patients (median age 10) were retrospectively planned with three techniques: three‐dimensional conformal radiation therapy (3D CRT), volumetric‐modulated arc therapy (VMAT), and helical tomotherapy (HT). VMAT plans consisted of one superior and one inferior full arc, and tomotherapy plans were created using a 5.02 cm field width and helical pitch of 0.287. Each plan was normalized to 95% of target volume (whole brain and spinal cord) receiving prescription dose 23.4 Gy in 13 fractions. Using an in‐house MATLAB code and DVH data from each plan, the three techniques were evaluated based on biologically effective uniform dose (Dfalse¯false¯), the complication‐free tumor control probability (normalP+), and the width of the therapeutically beneficial range. Overall, 3D CRT and VMAT plans had similar values of Dfalse¯false¯ (24.1 and 24.2 Gy), while HT had a Dfalse¯false¯ slightly lower (23.6 Gy). The average values of the normalP+ index were 64.6, 67.4, and 56.6% for 3D CRT, VMAT, and HT plans, respectively, with the VMAT plans having a statistically significant increase in normalP+. Optimal values of Dfalse¯false¯ were 28.4, 33.0, and 31.9 Gy for 3D CRT, VMAT, and HT plans, respectively. Although normalP+ values that correspond to the initial dose prescription were lower for HT, after optimizing the Dfalse¯false¯ prescription level, the optimal normalP+ became 94.1, 99.5, and 99.6% for 3D CRT, VMAT, and HT, respectively, with the VMAT and HT plans having statistically significant increases in normalP+. If the optimal dose level is prescribed using a radiobiological evaluation method, as opposed to a purely dosimetric one, the two IMRT techniques, VMAT and HT, will yield largest overall benefit to CSI patients by maximizing tumor control and limiting normal tissue injury. Using VMAT or HT may provide these pediatric patients with better long‐term outcomes after radiotherapy.PACS number: 87.55.dk

{normalP}_{+}

and

P_{B}

for the three modalities (approximately 57%–67%) were found to reasonably agree with other published data (31‐33) . Using a paired t ‐test (

p < 0.05

), it was found that there was a significant difference between the

{normalP}_{+}

values of VMAT and 3D CRT (

p = 0.004

), as well as between the values of VMAT and those of HT (

p < 0.0001

).…”

Section: Resultssupporting

confidence: 85%

Section: Methodsmentioning

confidence: 99%

Comparing conformal, arc radiotherapy and helical tomotherapy in craniospinal irradiation planning

Myers

J Applied Clin Med Phys

Papanikolaou

et al. 2014

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“…The difference in these values was obtained to estimate the expected clinical impact of the differences obtained by the dosimetric analysis. A detailed presentation of the software that was used for the radiobiological analysis can be found in the work by Su et al Resulting TCP/NTCP calculated from doses reported by Pinnacle 3 were used as reference values when comparing to TCP/NTCP calculations from doses reported by VeriSoft. Tables report the summary of the model parameter values used for the examined cancer cases .…”

Section: Methodsmentioning

confidence: 99%

Incorporating biological modeling into patient‐specific plan verification

Alexandrian

J Applied Clin Med Phys

Narayanasamy

et al. 2020

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Purpose Dose–volume histogram (DVH) measurements have been integrated into commercially available quality assurance systems to provide a metric for evaluating accuracy of delivery in addition to gamma analysis. We hypothesize that tumor control probability and normal tissue complication probability calculations can provide additional insight beyond conventional dose delivery verification methods. Methods A commercial quality assurance system was used to generate DVHs of treatment plan using the planning CT images and patient‐specific QA measurements on a phantom. Biological modeling was performed on the DVHs produced by both the treatment planning system and the quality assurance system. Results The complication‐free tumor control probability, P+, has been calculated for previously treated intensity modulated radiotherapy (IMRT) patients with diseases in the following sites: brain (−3.9% ± 5.8%), head‐neck (+4.8% ± 8.5%), lung (+7.8% ± 1.3%), pelvis (+7.1% ± 12.1%), and prostate (+0.5% ± 3.6%). Conclusion Dose measurements on a phantom can be used for pretreatment estimation of tumor control and normal tissue complication probabilities. Results in this study show how biological modeling can be used to provide additional insight about accuracy of delivery during pretreatment verification.

“…The tumor control probability (TCP) and normal tissue complication probability (NTCP) were calculated using an application previously developed at our institution to determine which plan would have the greatest therapeutic benefit. 23 The parameters used for calculating the TCP and NTCP values can be seen in Table 1, which were repeated from the work of Mavroidis et al . 24…”

Section: Methodsmentioning

confidence: 99%

VMAT Optimization and Dose Calculation in the Presence of Metallic Hip Prostheses

Parenica

Technol Cancer Res Treat

Jones

et al. 2019

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Introduction:This research quantifies and compares the effect of hip prostheses on dose distributions calculated using collapsed cone convolution superposition and Monte Carlo (with and without correcting for the density of the implant and surrounding tissues). The use of full volumetric modulated arc therapy arcs versus volumetric modulated arc therapy arcs avoiding the hip implants (skip arcs) was also studied.Materials and Methods:Six prostate patients with hip prostheses were included in this study. The hip prostheses and the streaking artifacts on the computed tomography images were contoured by a single physician, and full volumetric modulated arc therapy arcs were created in the Pinnacle3 TPS. Copies of each plan were made, and the doses were recalculated with the densities of the prostheses and surrounding tissues overridden. The plans were then exported to Monaco and recalculated using a Monte Carlo dose calculation algorithm, with and without densities of the prosthesis and surrounding tissues overridden.Results:With density overrides, Pinnacle3 had a 4.4% error for ion chamber measurements. Monaco was within 0.2% of ion chamber measurement when density overrides were used. On average, when density overrides were used in Pinnacle3 for patient dose calculations, the planning target volume D95 value dropped from 99.3% to 82.7%. Monaco also showed decreased planning target volume coverage when plans were recalculated with correct density information. Full arc plans (with density overrides) for the patient with a bilateral prosthesis provided significant bladder sparing and some rectal sparing compared to skip arc plans.Conclusion:When planning for prostate patients with hip prostheses, correct density information for implants and surrounding tissues should be used to optimize the plan and ensure optimal accuracy. If available, a Monte Carlo algorithm should be used as a second check. Full arcs could be used to spare dose to organs at risk, while maintaining adequate planning target volume coverage, when using a Monte Carlo dose calculation algorithm.