Stereotactic Radiotherapy of Malignancies in the Abdomen: Methodological aspects

Lax, Ingmar; Blomgren, Henric; Näslund, Ingemar; Svanström, Rut

doi:10.3109/02841869409121782

Cited by 504 publications

(253 citation statements)

References 12 publications

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“…The dose calculation was performed in the average intensity projection of 4D CT datasets. The dose prescription was according to the Nordic SBRT study group, adapted from the original work published by Lax et al (1) In this dose prescription protocol, doses to central parts of the PTV are about 50% higher than that prescribed at the periphery of the PTV. The prescription isodose level should be 67% of the dose at normalization point, which normally is close to the isocenter and/or the center of mass of the PTV.…”

Section: Methodsmentioning

confidence: 99%

“…The prescription isodose level should be 67% of the dose at normalization point, which normally is close to the isocenter and/or the center of mass of the PTV. The dose planning criteria are described more in detail in Lax et al (1) The prescribed dose was from 45 to 54 Gy in 3 to 5 fractions, depending on the size of the PTV. The plans used 3D conformal radiotherapy (CRT) technique and included five to nine coplanar nonopposing treatment fields with 6 MV photon beams.…”

Section: Methodsmentioning

confidence: 99%

“…After its first implementation to extracranial treatments reported by Lax et al (1) in 1994, SBRT has evolved to its present form. The principle of SBRT is based on delivering large doses to planning target volume (PTV) in a single fraction or in a few fractions.…”

Section: Introductionmentioning

confidence: 99%

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Performance of dose calculation algorithms from three generations in lung SBRT: comparison with full Monte Carlo‐based dose distributions

Ojala

Kapanen

Hyödynmaa

et al. 2014

J Applied Clin Med Phys

106

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The accuracy of dose calculation is a key challenge in stereotactic body radiotherapy (SBRT) of the lung. We have benchmarked three photon beam dose calculation algorithms — pencil beam convolution (PBC), anisotropic analytical algorithm (AAA), and Acuros XB (AXB) — implemented in a commercial treatment planning system (TPS), Varian Eclipse. Dose distributions from full Monte Carlo (MC) simulations were regarded as a reference. In the first stage, for four patients with central lung tumors, treatment plans using 3D conformal radiotherapy (CRT) technique applying 6 MV photon beams were made using the AXB algorithm, with planning criteria according to the Nordic SBRT study group. The plans were recalculated (with same number of monitor units (MUs) and identical field settings) using BEAMnrc and DOSXYZnrc MC codes. The MC‐calculated dose distributions were compared to corresponding AXB‐calculated dose distributions to assess the accuracy of the AXB algorithm, to which then other TPS algorithms were compared. In the second stage, treatment plans were made for ten patients with 3D CRT technique using both the PBC algorithm and the AAA. The plans were recalculated (with same number of MUs and identical field settings) with the AXB algorithm, then compared to original plans. Throughout the study, the comparisons were made as a function of the size of the planning target volume (PTV), using various dose‐volume histogram (DVH) and other parameters to quantitatively assess the plan quality. In the first stage also, 3D gamma analyses with threshold criteria 3normal%/3 mm and 2normal%/2 mm were applied. The AXB‐calculated dose distributions showed relatively high level of agreement in the light of 3D gamma analysis and DVH comparison against the full MC simulation, especially with large PTVs, but, with smaller PTVs, larger discrepancies were found. Gamma agreement index (GAI) values between 95.5% and 99.6% for all the plans with the threshold criteria 3normal%/3 mm were achieved, but 2normal%/2 mm threshold criteria showed larger discrepancies. The TPS algorithm comparison results showed large dose discrepancies in the PTV mean dose false(normalD50normal%false), nearly 60%, for the PBC algorithm, and differences of nearly 20% for the AAA, occurring also in the small PTV size range. This work suggests the application of independent plan verification, when the AAA or the AXB algorithm are utilized in lung SBRT having PTVs smaller than 20‐25 cc. The calculated data from this study can be used in converting the SBRT protocols based on type ‘a’ and/or type ‘b’ algorithms for the most recent generation type ‘c’ algorithms, such as the AXB algorithm.PACS numbers: 87.55.‐x, 87.55.D‐, 87.55.K‐, 87.55.kd, 87.55.Qr

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Performance of dose calculation algorithms from three generations in lung SBRT: comparison with full Monte Carlo‐based dose distributions

Ojala

Kapanen

Hyödynmaa

et al. 2014

J Applied Clin Med Phys

106

View full text Add to dashboard Cite

show abstract

“…It is an immobilization device that defines a stereotactic system of coordinates for the target position instead of basing on the anatomical landmarks such as bony structures or skin markers. 30,31 To reduce involuntary abdominal movements due to respiration, an abdominal compressor is attached to the SBF by a rigid arc, aiming at minimizing the mobility of targets close to the diaphragm by mechanically pressing the patients epigastrium.…”

Section: Treatment Simulationmentioning

confidence: 99%

Individually optimized stereotactic radiotherapy for pancreatic head tumors: A planning feasibility study

Buwenge

Cilla

Guido

et al. 2016

Reports of Practical Oncology & Radiotherapy

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“…[32][33][34][35][36] This was confirmed by Guckenberger M. et al who conducted a 4D-IGRT study in liver SBRT with acquisition of a CBCT study immediately before and after treatment delivery. Despite successful immobilization of the patient with a SBF, they observed considerable drifts in the target position independently from the bony anatomy in an order of 3.7 ± 2.2 mm on average.…”

Section: Discussionmentioning

confidence: 64%

Imaged-guided liver stereotactic body radiotherapy using VMAT and real-time adaptive tumor gating. Concerns about technique and preliminary clinical results

Llacer-Moscardo

Riou

Azria

et al. 2017

Reports of Practical Oncology & Radiotherapy

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Stereotactic Radiotherapy of Malignancies in the Abdomen: Methodological aspects

Cited by 504 publications

References 12 publications

Performance of dose calculation algorithms from three generations in lung SBRT: comparison with full Monte Carlo‐based dose distributions

Performance of dose calculation algorithms from three generations in lung SBRT: comparison with full Monte Carlo‐based dose distributions

Individually optimized stereotactic radiotherapy for pancreatic head tumors: A planning feasibility study

Imaged-guided liver stereotactic body radiotherapy using VMAT and real-time adaptive tumor gating. Concerns about technique and preliminary clinical results

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