Dataset Information

A multinational audit of small field output factors calculated by treatment planning systems used in radiotherapy.

ABSTRACT:

Background and purpose

An audit methodology for verifying the implementation of output factors (OFs) of small fields in treatment planning systems (TPSs) used in radiotherapy was developed and tested through a multinational research group and performed on a national level in five different countries.

Materials and methods

Centres participating in this study were asked to provide OFs calculated by their TPSs for 10?×?10?cm², 6?×?6?cm², 4?×?4?cm², 3?×?3?cm² and 2?×?2?cm² field sizes using an SSD of 100?cm. The ratio of these calculated OFs to reference OFs was analysed. The action limit was ±3% for the 2?×?2?cm² field and ±2% for all other fields.

Results

OFs for more than 200 different beams were collected in total. On average, the OFs for small fields calculated by TPSs were generally larger than measured reference data. These deviations increased with decreasing field size. On a national level, 30% and 31% of the calculated OFs of the 2?×?2?cm² field exceeded the action limit of 3% for nominal beam energies of 6?MV and for nominal beam energies higher than 6 MV, respectively.

Conclusion

Modern TPS beam models generally overestimate the OFs for small fields. The verification of calculated small field OFs is a vital step and should be included when commissioning a TPS. The methodology outlined in this study can be used to identify potential discrepancies in clinical beam models.

SUBMITTER: Lechner W

PROVIDER: S-EPMC7807586 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

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Publications

A multinational audit of small field output factors calculated by treatment planning systems used in radiotherapy.

Lechner Wolfgang W Wesolowska Paulina P Azangwe Godfrey G Arib Mehenna M Alves Victor Gabriel Leandro VGL Suming Luo L Ekendahl Daniela D Bulski Wojciech W Samper José Luis Alonso JLA Vinatha Sumanth Panyam SP Siri Srimanoroth S Tomsej Milan M Tenhunen Mikko M Povall Julie J Kry Stephen F SF Followill David S DS Thwaites David I DI Georg Dietmar D Izewska Joanna J

Physics and imaging in radiation oncology 20180101

<h4>Background and purpose</h4>An audit methodology for verifying the implementation of output factors (OFs) of small fields in treatment planning systems (TPSs) used in radiotherapy was developed and tested through a multinational research group and performed on a national level in five different countries.<h4>Materials and methods</h4>Centres participating in this study were asked to provide OFs calculated by their TPSs for 10 × 10 cm<sup>2</sup>, 6 × 6 cm<sup>2</sup>, 4 × 4 cm<sup>2</sup>, 3  ...[more]

PMID: 33458370

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Project description:PurposeTo develop and evaluate an automated whole-brain radiotherapy (WBRT) treatment planning pipeline with a deep learning-based auto-contouring and customizable landmark-based field aperture design.MethodsThe pipeline consisted of the following steps: (1) Auto-contour normal structures on computed tomography scans and digitally reconstructed radiographs using deep learning techniques, (2) locate the landmark structures using the beam's-eye-view, (3) generate field apertures based on eight different landmark rules addressing different clinical purposes and physician preferences. Two parallel approaches for generating field apertures were developed for quality control. The performance of the generated field shapes and dose distributions were compared with the original clinical plans. The clinical acceptability of the plans was assessed by five radiation oncologists from four hospitals.ResultsThe performance of the generated field apertures was evaluated by the Hausdorff distance (HD) and mean surface distance (MSD) from 182 patients' field apertures used in the clinic. The average HD and MSD for the generated field apertures were 16 ± 7 and 7 ± 3 mm for the first approach, respectively, and 17 ± 7 and 7 ± 3 mm, respectively, for the second approach. The differences regarding HD and MSD between the first and the second approaches were 1 ± 2 and 1 ± 3 mm, respectively. A clinical review of the field aperture design, conducted using 30 patients, achieved a 100% acceptance rate for both the first and second approaches, and the plan review achieved a 100% acceptance rate for the first approach and a 93% acceptance rate for the second approach. The average acceptance rate for meeting lens dosimetric recommendations was 80% (left lens) and 77% (right lens) for the first approach, and 70% (both left and right lenses) for the second approach, compared with 50% (left lens) and 53% (right lens) for the clinical plans.ConclusionThis study provided an automated pipeline with two field aperture generation approaches to automatically generate WBRT treatment plans. Both quantitative and qualitative evaluations demonstrated that our novel pipeline was comparable with the original clinical plans.

Dataset Information

A multinational audit of small field output factors calculated by treatment planning systems used in radiotherapy.

Background and purpose

Materials and methods

Results

Conclusion

Publications

A multinational audit of small field output factors calculated by treatment planning systems used in radiotherapy.

Similar Datasets

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