Characterization of a novel 2D array dosimeter for patient‐specific quality assurance with volumetric arc therapy

Stathakis, Sotirios; Myers, Pamela; Esquivel, Carlos O.; Mavroidis, Panayiotis; Papanikolaou, Nikos

doi:10.1118/1.4812415

Cited by 48 publications

(51 citation statements)

References 13 publications

(14 reference statements)

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“…Finally, the comparison between the absolute dose and the dose measured by the central chamber of the array, assessed during the commissioning of the phantom for the K user determination, furnished worse agreement than what was reported in the literature (about 5% difference for both the LINACs vs 1–2% in Stathakis et al)16, probably due to array‐related characteristics. However, it was found that the K user was comparable with the K cross , obtained by the comparison with the TPS expected value (Δ ≤ 1%).…”

Section: Discussionmentioning

confidence: 61%

“…The 2D‐Array together with Octavius ® ‐4D are widely described in the literature 1, 16. Briefly, the 2D‐Array consisted in a matrix of 729 vented ionization chambers distant 10 mm from center to center, embedded in a 27 × 27 array.…”

Section: Methodsmentioning

confidence: 99%

“…Nowadays, PTW Octavius ® ‐4D is widely used in the QA process, and its performances were already evaluated also for stereotactic treatments,10, 11, 12 with flattening filter free (FFF) technology13 or for testing respiratory‐gated VMAT delivery 14. In spite of this, some aspects of its performances were only partially investigated 1, 15, 16. This study aims to characterize the 2D‐Array in Octavius ® ‐4D for both IMRT and VMAT delivery techniques.…”

Section: Introductionmentioning

confidence: 99%

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Practical application of Octavius^®‐4D: Characteristics and criticalities for IMRT and VMAT verification

Urso

Lorusso

Marzoli

et al. 2018

J Applied Clin Med Phys

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Octavius®‐4D is a very effective device in radiotherapy treatment quality assurance (QA), due to its simple set‐up and analysis package. However, even if it is widely used, its main characteristics and criticalities were only partially investigated. Taking start from its commissioning, the aim of this work was to study the main dependencies of the device response. The outcome dependence was studied comparing results by different delivery techniques [Intensity Modulated Radiation Therapy, IMRT (n = 29) and RapidArc, RA (n = 15)], anatomical regions [15 head/neck, 19 pelvis and 10 pancreas] and linear accelerators [DHX (n = 14) and Trilogy (n = 30)]. Moreover, the agreement dependency on the section of the phantom was assessed. Plan evaluations obtained by 2D, 3D, and volumetric γ‐index (both local and global) were also compared. Generally, high dose gradient resulted critically managed by the assembly, with a smoother effect in RA technique. Worse agreements emerged in the 2D γ‐index vs those of 3D and volumetric (P < 0.001), that were instead statistically comparable in global metric (P > 0.300). Volumetric plan evaluation was coherent with the average of passing rates on the 3 phantom axes (r ≥ 0.9), but transversal section provided best agreements vs sagittal and coronal ones (P < 0.050). The three studied districts furnished comparable results (P > 0.050) while the two LINACs provided different agreements (P < 0.005). The study pointed out that the phantom transversal section better fits the planned dose distribution, so this should be accounted when a two‐dimensional evaluation is needed. Moreover, the major reliability of the 3D metric with respect to the 2D one, as it better agrees with the dosimetric evaluation on the whole volume, suggests that it should be preferred in a two‐dimensional evaluation. Better agreements, obtained with RA vs IMRT technique, confirm that Octavius®‐4D is specifically conceived for rotational delivery. Lastly, the assembly resulted sensitive to different technology.

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Section: Discussionmentioning

confidence: 61%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Practical application of Octavius^®‐4D: Characteristics and criticalities for IMRT and VMAT verification

Urso

Lorusso

Marzoli

et al. 2018

J Applied Clin Med Phys

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“…On the other hand, direct comparison of the planned and deliverable DVHs exhibits higher sensitivity and specificity, and is expected to be more clinically meaningful and intuitive to both the physician and the physicist 7 , 10 , 11 . Semiempirical volumetric dose reconstruction, based on the array measurements, was previously reported on geometrical phantoms 12 , 13 , 14 , 15 and patient CT datasets 16 , 17 . Following this trend, a recently released Delta 4 (ScandiDos AB, Uppsala, Sweden) software module called Anatomy was purchased at our clinic.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of semiempirical VMAT dose reconstruction on a patient dataset based on biplanar diode array measurements

Stambaugh

Opp

Wasserman

et al. 2014

J Applied Clin Med Phys

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We report the results of a preclinical evaluation of recently introduced commercial tools for 3D patient IMRT/VMAT dose reconstruction, the Delta4 Anatomy calculation algorithm. Based on the same initial measurement, volumetric dose can be reconstructed in two ways. Three‐dimensional dose on the Delta4 phantom can be obtained by renormalizing the planned dose distribution by the measurement values (D4 Interpolation). Alternatively, incident fluence can be approximated from the phantom measurement and used for volumetric dose calculation on an arbitrary (patient) dataset with a pencil beam algorithm (Delta4 PB). The primary basis for comparison was 3D dose obtained by previously validated measurement‐guided planned dose perturbation method (ACPDP), based on the ArcCHECK dosimeter with 3DVH software. For five clinical VMAT plans, D4 Interpolation agreed well with ACPDP on a homogeneous cylindrical phantom according to gamma analysis with local dose‐error normalization. The average agreement rates were 98.2%±1.3% (1 SD), (range 97.0%‐100%) and 92.8%±3.9% (89.5%‐99.2%), for the 3%/3 mm and 2%/2 mm criteria, respectively. On a similar geometric phantom, D4 PB demonstrated substantially lower agreement rates with ACPDP: 88.6%±6.8% (81.2%‐96.1%) and 72.4%±8.4% (62.1%‐81.1%), for 3%/3 mm and 2%/2 mm, respectively. The average agreement rates on the heterogeneous patients' CT datasets are lower yet: 81.2%±8.6% (70.4%‐90.4%) and 64.6%±8.4% (56.5%‐74.7%), respectively, for the same two criteria sets. For both threshold combinations, matched analysis of variance (ANOVA) multiple comparisons showed statistically significant differences in mean agreement rates (p<0.05) for D4 Interpolation versus ACPDP on one hand, and D4 PB versus ACPDP on either cylindrical or patient dataset on the other hand. Based on the favorable D4 Interpolation results for VMAT plans, the resolution of the reconstruction method rather than hardware design is likely to be responsible for D4 PB limitations.PACS number: 87.55Qr

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“…Different QA measurement techniques in IMRT exist, making use of 2D detector array [5][6][7][8], single ion chamber in phantom for point dose measurements [9][10][11] or using specific phantoms with 2D dose measurement devices and 3D dose reconstruction software [12][13][14]. One disadvantage of these approaches is that measurements are generally compared with calculations by the TPS and it is difficult to give interpretation and to address the deviations between calculated and measured doses to failures of the accelerator performance or to the calculation algorithm.…”

Section: Introductionmentioning

confidence: 99%

Primo software as a tool for Monte Carlo simulations of intensity modulated radiotherapy: A feasibility study

et al. 2016

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Background: IMRT provides higher dose conformation to the target and dose sparing to surrounding tissues than 3DCRT. Monte Carlo method in Medical Physics is not a novelty to approach dosimetric problems. A new PENELOPE based code named PRIMO recently was published. The most intriguing features of PRIMO are the user-friendly approach, the stand-alone property and the built-in definition of different linear accelerators models. Nevertheless, IMRT simulations are not yet implemented. Methods: A Varian Trilogy with a Millennium120 MLC and a Varian Novalis with 120HD MLC were studied. A RW3 multi-slab phantom was irradiated with Gafchromic films inserted between slabs. An Expression 10000XL scanner (Seiko Epson Corp., Nagano, Japan) was used to digitalize the films. PTW-Verisoft software using the global Gamma Function (2%, 2 mm) was used to compare simulated and experimental results. The primary beam parameters were adjusted to best match reference data previously obtained in a water phantom. Static MLC simulations were performed to validate the MLC models in use. Two Dynamic IMRT preliminary tests were performed with leaves moving with constant and variable speed. A further test of an in phantom delivery of a real IMRT field allowed simulating a clinical-like MLC modulation.

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Characterization of a novel 2D array dosimeter for patient‐specific quality assurance with volumetric arc therapy

Cited by 48 publications

References 13 publications

Practical application of Octavius^®‐4D: Characteristics and criticalities for IMRT and VMAT verification

Practical application of Octavius^®‐4D: Characteristics and criticalities for IMRT and VMAT verification

Evaluation of semiempirical VMAT dose reconstruction on a patient dataset based on biplanar diode array measurements

Primo software as a tool for Monte Carlo simulations of intensity modulated radiotherapy: A feasibility study

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Characterization of a novel 2D array dosimeter for patient‐specific quality assurance with volumetric arc therapy

Cited by 48 publications

References 13 publications

Practical application of Octavius®‐4D: Characteristics and criticalities for IMRT and VMAT verification

Practical application of Octavius®‐4D: Characteristics and criticalities for IMRT and VMAT verification

Evaluation of semiempirical VMAT dose reconstruction on a patient dataset based on biplanar diode array measurements

Primo software as a tool for Monte Carlo simulations of intensity modulated radiotherapy: A feasibility study

Contact Info

Product

Resources

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Practical application of Octavius^®‐4D: Characteristics and criticalities for IMRT and VMAT verification

Practical application of Octavius^®‐4D: Characteristics and criticalities for IMRT and VMAT verification