A.W. Sharfo
Erasmus University Rotterdam
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by A.W. Sharfo.
Radiotherapy and Oncology | 2015
A.W. Sharfo; P. Voet; S. Breedveld; Jan Willem M. Mens; Mischa S. Hoogeman; B.J.M. Heijmen
BACKGROUND AND PURPOSE In a published study on cervical cancer, 5-beam IMRT was inferior to single arc VMAT. Here we compare 9, 12, and 20 beam IMRT with single and dual arc VMAT. MATERIAL AND METHODS For each of 10 patients, automated plan generation with the in-house Erasmus-iCycle optimizer was used to assist an expert planner in generating the five plans with the clinical TPS. RESULTS For each patient, all plans were clinically acceptable with a high and similar PTV coverage. OAR sparing increased when going from 9 to 12 to 20 IMRT beams, and from single to dual arc VMAT. For all patients, 12 and 20 beam IMRT were superior to single and dual arc VMAT, with substantial variations in gain among the study patients. As expected, delivery of VMAT plans was significantly faster than delivery of IMRT plans. CONCLUSIONS Often reported increased plan quality for VMAT compared to IMRT has not been observed for cervical cancer. Twenty and 12 beam IMRT plans had a higher quality than single and dual arc VMAT. For individual patients, the optimal delivery technique depends on a complex trade-off between plan quality and treatment time that may change with introduction of faster delivery systems.
PLOS ONE | 2016
A.W. Sharfo; S. Breedveld; P. Voet; S.T. Heijkoop; Jan Willem M. Mens; Mischa S. Hoogeman; B.J.M. Heijmen
Purpose To develop and validate fully automated generation of VMAT plan-libraries for plan-of-the-day adaptive radiotherapy in locally-advanced cervical cancer. Material and Methods Our framework for fully automated treatment plan generation (Erasmus-iCycle) was adapted to create dual-arc VMAT treatment plan libraries for cervical cancer patients. For each of 34 patients, automatically generated VMAT plans (autoVMAT) were compared to manually generated, clinically delivered 9-beam IMRT plans (CLINICAL), and to dual-arc VMAT plans generated manually by an expert planner (manVMAT). Furthermore, all plans were benchmarked against 20-beam equi-angular IMRT plans (autoIMRT). For all plans, a PTV coverage of 99.5% by at least 95% of the prescribed dose (46 Gy) had the highest planning priority, followed by minimization of V45Gy for small bowel (SB). Other OARs considered were bladder, rectum, and sigmoid. Results All plans had a highly similar PTV coverage, within the clinical constraints (above). After plan normalizations for exactly equal median PTV doses in corresponding plans, all evaluated OAR parameters in autoVMAT plans were on average lower than in the CLINICAL plans with an average reduction in SB V45Gy of 34.6% (p<0.001). For 41/44 autoVMAT plans, SB V45Gy was lower than for manVMAT (p<0.001, average reduction 30.3%), while SB V15Gy increased by 2.3% (p = 0.011). AutoIMRT reduced SB V45Gy by another 2.7% compared to autoVMAT, while also resulting in a 9.0% reduction in SB V15Gy (p<0.001), but with a prolonged delivery time. Differences between manVMAT and autoVMAT in bladder, rectal and sigmoid doses were ≤ 1%. Improvements in SB dose delivery with autoVMAT instead of manVMAT were higher for empty bladder PTVs compared to full bladder PTVs, due to differences in concavity of the PTVs. Conclusions Quality of automatically generated VMAT plans was superior to manually generated plans. Automatic VMAT plan generation for cervical cancer has been implemented in our clinical routine. Due to the achieved workload reduction, extension of plan libraries has become feasible.
Radiotherapy and Oncology | 2017
A.W. Sharfo; M. Dirkx; S. Breedveld; Alejandra Méndez Romero; B.J.M. Heijmen
PURPOSE To propose a novel treatment approach, designated VMAT+, involving addition of <5 IMRT beams with computer-optimized non-coplanar orientations to VMAT, and evaluate it for liver Stereotactic Body Radiation Therapy (SBRT). VMAT+ is investigated as an alternative for (1) coplanar VMAT and (2) multi-beam non-coplanar treatment. METHODS/MATERIALS For fifteen patients with liver metastases, VMAT+ plans were compared with (1) dual-arc VMAT and (2) 25-beam, non-coplanar treatment with computer-optimized beam orientations (25-NCP). All plans were generated fully automatically for delivery of the highest feasible tumor Biologically Effective Dose (BED). OAR doses, intermediate-dose-spillage, dose-compactness, and measured delivery times were evaluated. RESULTS With VMAT+ the maximum achievable tumor BED was equal to that of 25-NCP. Conversely, VMAT resulted in a lower tumor BED in 5 patients. Compared to VMAT, VMAT+ yielded significant dose reductions in OARs. Intermediate-dose-spillage and dose-compactness were significantly improved by 9.8% and 17.3% (p≤0.002), respectively. Treatment times with VMAT+ were only enhanced by 4.1min on average, compared to VMAT (8.4min). Improvements in OAR sparing with 25-NCP, compared to VMAT+, were generally modest and/or statistically insignificant, while delivery times were on average 20.5min longer. CONCLUSIONS For liver SBRT, VMAT+ is equivalent to time-consuming treatment with 25 non-coplanar beams in terms of achievable tumor BED. Compared to VMAT, OAR sparing and intermediate-dose-spillage are significantly improved, with minor increase in delivery time.
Radiotherapy and Oncology | 2017
Steven J.M. Habraken; A.W. Sharfo; Jeroen Buijsen; Wilko F.A.R. Verbakel; Cornelis J.A. Haasbeek; Michel Öllers; Henrike Westerveld; Niek van Wieringen; O. Reerink; E. Seravalli; Pètra M. Braam; M. Wendling; T. Lacornerie; Xavier Mirabel; Reinhilde Weytjens; L. Depuydt; Stephanie Tanadini-Lang; Oliver Riesterer; Karin Haustermans; Tom Depuydt; Roy S. Dwarkasing; F. Willemssen; B.J.M. Heijmen; Alejandra Méndez Romero
BACKGROUND AND PURPOSE The TRENDY trial is an international multi-center phase-II study, randomizing hepatocellular carcinoma (HCC) patients between transarterial chemoembolization (TACE) and stereotactic body radiation therapy (SBRT) with a target dose of 48-54 Gy in six fractions. The radiotherapy quality assurance (QA) program, including prospective plan feedback based on automated treatment planning, is described and results are reported. MATERIALS AND METHODS Scans of a single patient were used as a benchmark case. Contours submitted by nine participating centers were compared with reference contours. The subsequent planning round was based on a single set of contours. A total of 20 plans from participating centers, including 12 from the benchmark case, 5 from a clinical pilot and 3 from the first study patients, were compared to automatically generated VMAT plans. RESULTS For the submitted liver contours, Dice Similarity Coefficients (DSC) with the reference delineation ranged from 0.925 to 0.954. For the GTV, the DSC varied between 0.721 and 0.876. For the 12 plans on the benchmark case, healthy liver normal-tissue complication probabilities (NTCPs) ranged from 0.2% to 22.2% with little correlation between NCTP and PTV-D95% (R2 < 0.3). Four protocol deviations were detected in the set of 20 treatment plans. Comparison with co-planar autoVMAT QA plans revealed these were due to too high target dose and suboptimal planning. Overall, autoVMAT resulted in an average liver NTCP reduction of 2.2 percent point (range: 16.2 percent point to -1.8 percent point, p = 0.03), and lower doses to the healthy liver (p < 0.01) and gastrointestinal organs at risk (p < 0.001). CONCLUSIONS Delineation variation resulted in feedback to participating centers. Automated treatment planning can play an important role in clinical trials for prospective plan QA as suboptimal plans were detected.
Radiotherapy and Oncology | 2016
Mariska A.E. van de Sande; Carien L. Creutzberg; Steven van de Water; A.W. Sharfo; Mischa S. Hoogeman
In this dosimetric comparison study it was shown that IMPT with robust planning reduces dose to surrounding organs in cervical and endometrial cancer treatment compared with IMRT. Especially for the para-aortic region, clinically relevant dose reductions were obtained for kidneys, spinal cord and bowel, justifying the use of proton therapy for this indication.
Radiotherapy and Oncology | 2018
A.W. Sharfo; M. Dirkx; R. Bijman; W. Schillemans; S. Breedveld; Shafak Aluwini; Floris J. Pos; Luca Incrocci; B.J.M. Heijmen
PURPOSE/OBJECTIVE Assess to what extent the use of automated treatment planning would have reduced organ-at-risk dose delivery observed in the randomized HYPRO trial for prostate cancer, and estimate related toxicity reductions. Investigate to what extent improved plan quality for hypofractionation scheme as achieved with automated planning can potentially reduce observed enhanced toxicity for the investigated hypofractionation scheme to levels observed for conventional fractionation scheme. MATERIAL/METHODS For 725 trial patients, VMAT plans were generated with an algorithm for automated multi-criterial plan generation (autoVMAT). All clinically delivered plans (CLINICAL), generated with commonly applied interactive trial-and-error planning were also available for the investigations. Analyses were based on dose-volume histograms (DVH) and predicted normal tissue complication probabilities (NTCP) for late gastrointestinal (GI) toxicity. RESULTS Compared to CLINICAL, autoVMAT plans had similar or higher PTV coverage, while large and statistically significant OAR sparing was achieved. Mean doses in the rectum, anus and bladder were reduced by 7.8 ± 4.7 Gy, 7.9 ± 6.0 Gy and 4.2 ± 2.9 Gy, respectively (p < 0.001). NTCPs for late grade ≥2 GI toxicity, rectal bleeding and stool incontinence were reduced from 23.3 ± 9.1% to 19.7 ± 8.9%, from 9.7 ± 2.8% to 8.2 ± 2.8%, and from 16.8 ± 8.5% to 13.1 ± 7.2%, respectively (p < 0.001). Reductions in rectal bleeding NTCP were observed for all published Equivalent Uniform Dose volume parameters, n. AutoVMAT allowed hypofractionation with predicted toxicity similar to conventional fractionation with CLINICAL plans. CONCLUSION Compared to CLINICAL, autoVMAT had superior plan quality, with meaningful NTCP reductions for both conventional fractionation and hypofractionation schemes. AutoVMAT plans might reduce toxicity for hypofractionation to levels that were clinically observed (and accepted) for conventional fractionation. This may be relevant when considering clinical use of the investigated hypofractionation schedule with relatively high fraction dose (3.4 Gy).
Radiotherapy and Oncology | 2016
S.T. Heijkoop; G.H. Westerveld; N. Bijker; R. Feije; A.W. Sharfo; N. Van Wieringen; Jan Willem M. Mens; B.J.M. Heijmen; Lukas J.A. Stalpers; Mischa S. Hoogeman
Purpose or Objective: In order to reduce dose to the small bowel, some institutions treat patients with gynecological cancer in prone position using a small-bowel displacement device (belly board). This practice is based on dosimetric advantages found in the past for 3DCRT and/or the use of large margins. It is unknown to what extent those advantages are persistent using modern intensity-modulated delivery techniques (e.g. IMRT or VMAT) and adaptive treatment approaches with small CTV-to-PTV margins. The aim of this study is to determine the best patient setup position (prone or supine) in terms of OAR sparing for various CTV-to-PTV margins and modern dose delivery.
Radiotherapy and Oncology | 2016
M. Van de Sande; Carien L. Creutzberg; S. Van de Water; A.W. Sharfo; Mischa S. Hoogeman
Purpose or Objective: Combining the capabilities of high resolution soft tissue MR imaging and intensity modulated radiation therapy into a hybrid device has the potential to increase the accuracy of radiotherapy. However, it is known that the magnetic field of the MR manipulates the trajectory of the secondary electrons and leads to a deviation of dose especially at the interfaces between high and low density materials. This study aims to introduce a routine for the evaluation of magnetic field effects to dose delivery and plan optimization using Monte Carlo simulations.
Radiation Oncology | 2017
Daniel Buergy; A.W. Sharfo; B.J.M. Heijmen; P. Voet; S. Breedveld; Frederik Wenz; Frank Lohr; Florian Stieler
International Journal of Radiation Oncology Biology Physics | 2016
S.T. Heijkoop; Henrike Westerveld; N. Bijker; Raphael Feije; A.W. Sharfo; Niek van Wieringen; Jan Willem M. Mens; Lukas J.A. Stalpers; Mischa S. Hoogeman