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A validation study of a dedicated software for an automated in vivo dosimetry control in radiotherapy. Med Biol Eng Comput 2018; 56:1939-1947. [PMID: 29682674 DOI: 10.1007/s11517-018-1822-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 03/26/2018] [Indexed: 10/17/2022]
Abstract
In vivo dosimetry (IVD) is the last step of a radiotherapy quality control program aimed to ensure that the dose delivered is in agreement with that prescribed. IVD procedures based on single detectors are time-consuming and impossible to use for the modern radiotherapy techniques, based on static or kinetic beams (modulated in intensity fluence); this means that more efficient and practical methods are highly recommended. The practical method SOFTDISO, based on the use of electronic portal image device (EPID), provides two tests (i) the R ratio between the reconstructed and the planned isocenter doses to verify an agreement within 5% and (ii) the γ-analysis of the EPID images, to verify γ% ≥ 90% and γmean ≤ 0.4. This paper reports the results of 11,357 IVD tests carried out for 823 patients treated by three-dimensional conformal radiation therapy and volumetric modulated arc therapy techniques. In particular, the dose disagreements are reported distinguishing two kinds of causes, those of (i) class 1 that includes the errors due to inadequate quality controls and (ii) the class 2, due to patient morphological changes. About the tests out of tolerance, 6% were by VMAT and 21% by 3DCRT, but taking into account the only class 1 of errors, i.e., removing the causes of class 2, only 7% of patients examined presented at least one of the three mean indexes out of tolerance. The workload for IVD on 9 patients/day per linac is about 52 min/day but recently, a new automated SOFTDISO version has been implemented to reduce the time to about 34 min/day.
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Setup in a clinical workflow and impact on radiotherapy routine of an in vivo dosimetry procedure with an electronic portal imaging device. PLoS One 2018; 13:e0192686. [PMID: 29432473 PMCID: PMC5809064 DOI: 10.1371/journal.pone.0192686] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 01/29/2018] [Indexed: 12/21/2022] Open
Abstract
High conformal techniques such as intensity-modulated radiation therapy and volumetric-modulated arc therapy are widely used in overloaded radiotherapy departments. In vivo dosimetric screening is essential in this environment to avoid important dosimetric errors. This work examines the feasibility of introducing in vivo dosimetry (IVD) checks in a radiotherapy routine. The causes of dosimetric disagreements between delivered and planned treatments were identified and corrected during the course of treatment. The efficiency of the corrections performed and the added workload needed for the entire procedure were evaluated. The IVD procedure was based on an electronic portal imaging device. A total of 3682 IVD tests were performed for 147 patients who underwent head and neck, abdomen, pelvis, breast, and thorax radiotherapy treatments. Two types of indices were evaluated and used to determine if the IVD tests were within tolerance levels: the ratio R between the reconstructed and planned isocentre doses and a transit dosimetry based on the γ-analysis of the electronic portal images. The causes of test outside tolerance level were investigated and corrected and IVD test was repeated during subsequent fraction. The time needed for each step of the IVD procedure was registered. Pelvis, abdomen, and head and neck treatments had 10% of tests out of tolerance whereas breast and thorax treatments accounted for up to 25%. The patient setup was the main cause of 90% of the IVD tests out of tolerance and the remaining 10% was due to patient morphological changes. An average time of 42 min per day was sufficient to monitor a daily workload of 60 patients in treatment. This work shows that IVD performed with an electronic portal imaging device is feasible in an overloaded department and enables the timely realignment of the treatment quality indices in order to achieve a patient’s final treatment compliant with the one prescribed.
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Falco MD, Giancaterino S, De Nicola A, Adorante N, De Lorenzo RG, Di Tommaso M, Vinciguerra A, Trignani M, Perrotti F, Allajbej A, Fidanzio A, Greco F, Grusio M, Genovesi D, Piermattei A. A Feasibility Study for in vivo Dosimetry Procedure in Routine Clinical Practice. Technol Cancer Res Treat 2018; 17:1533033818779201. [PMID: 29871570 PMCID: PMC5992805 DOI: 10.1177/1533033818779201] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Purpose: The aim of the in vivo dosimetry, during the fractionated radiation therapy, is the verification of the correct dose delivery to patient. Nowadays, in vivo dosimetry procedures for photon beams are based on the use of the electronic portal imaging device and dedicated software to elaborate electronic portal imaging device images. Methods: In total, 8474 in vivo dosimetry tests were carried out for 386 patients treated with 3-dimensional conformal radiotherapy, intensity-modulated radiotherapy, and volumetric modulated arc therapy techniques, using the SOFTDISO. SOFTDISO is a dedicated software that uses electronic portal imaging device images in order to (1) calculate the R index, that is, the ratio between daily reconstructed dose and the planned one at isocenter and (2) perform a γ-like analysis between the signals, S, of a reference electronic portal imaging device image and that obtained in a daily fraction. It supplies 2 indexes, the percentage γ% of points with γ < 1 and the mean γ value, γmean. In γ-like analysis, the pass criteria for the signals agreement ΔS% and distance to agreement Δd have been selected based on the clinical experience and technology used. The adopted tolerance levels for the 3 indexes were fixed in 0.95 ≤ R ≤ 1.05, γ% ≥ 90%, and γmean ≤ 0.5. Results: The results of R ratio, γ-like, and a visual inspection of these data reported on a monitor screen permitted to individuate 2 classes of errors (1) class 1 that included errors due to inadequate standard quality controls and (2) class 2, due to patient morphological changes. Depending on the technique and anatomical site, a maximum of 18% of tests had at least 1 index out of tolerance; once removed the causes of class-1 errors, almost all patients (except patients with 4 lung and 2 breast cancer treated with 3-dimensional conformal radiotherapy) presented mean indexes values (R¯, γ¯%, and γ¯mean
) within tolerance at the end of treatment course. Class-2 errors were found in some patients. Conclusions: The in vivo dosimetry procedure with SOFTDISO resulted easily implementable, able to individuate errors with a limited workload.
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Affiliation(s)
- Maria D Falco
- 1 Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Stefano Giancaterino
- 1 Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Andrea De Nicola
- 1 Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Nico Adorante
- 1 Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Ramon Gimenez De Lorenzo
- 1 Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Monica Di Tommaso
- 1 Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Annamaria Vinciguerra
- 1 Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Marianna Trignani
- 1 Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Francesca Perrotti
- 1 Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Albina Allajbej
- 1 Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Andrea Fidanzio
- 2 Unità Operativa di Fisica Sanitaria; Fondazione Policlinico Universitario A. Gemelli, Università Cattolica del Sacro Cuore, Roma, Italy
| | - Francesca Greco
- 2 Unità Operativa di Fisica Sanitaria; Fondazione Policlinico Universitario A. Gemelli, Università Cattolica del Sacro Cuore, Roma, Italy
| | - Mattia Grusio
- 2 Unità Operativa di Fisica Sanitaria; Fondazione Policlinico Universitario A. Gemelli, Università Cattolica del Sacro Cuore, Roma, Italy
| | - Domenico Genovesi
- 1 Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Angelo Piermattei
- 2 Unità Operativa di Fisica Sanitaria; Fondazione Policlinico Universitario A. Gemelli, Università Cattolica del Sacro Cuore, Roma, Italy
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Abstract
PURPOSE To improve patient safety and treatment quality, verification of dose delivery in radiotherapy is desirable. We present a simple, easy-to-implement, open-source method for in vivo planar dosimetry of conformal radiotherapy by electronic portal imaging device (EPID). METHODS Correlation ratios, which relate dose in the mid-depth of slab phantoms to transit EPID signal, were determined for multiple phantom thicknesses and field sizes. Off-axis dose is corrected for by means of model-based convolution. We tested efficacy of dose reconstruction through measurements with off-reference values of attenuator thickness, field size, and monitor units. We quantified the dose calculation error in the presence of thickness changes to simulate anatomical or setup variations. An example of dose calculation on patient data is provided. RESULTS With varying phantom thickness, field size, and monitor units, dose reconstruction was almost always within 3% of planned dose. In the presence of thickness changes from planning CT, the dose discrepancy is exaggerated by up to approximately 1.5% for 1 cm changes upstream of the isocenter plane and 4% for 1 cm changes downstream. CONCLUSION Our novel electronic portal imaging device in vivo dosimetry allows clinically accurate 2-dimensional reconstruction of dose inside a phantom/patient at isocenter depth. Due to its simplicity, commissioning can be performed in a few hours per energy and may be modified to the user's needs. It may provide useful dose delivery information to detect harmful errors, guide adaptive radiotherapy, and assure quality of treatment.
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Affiliation(s)
- Stefano Peca
- Department of Physics and Astronomy, University of Calgary, Calgary, AB, Canada.,Department of Medical Physics, Tom Baker Cancer Centre, Calgary, AB, Canada
| | - Derek Wilson Brown
- Department of Physics and Astronomy, University of Calgary, Calgary, AB, Canada.,Department of Radiation Medicine and Applied Sciences, Moores Cancer Center, UC San Diego, La Jolla, CA, USA
| | - Wendy Lani Smith
- Department of Physics and Astronomy, University of Calgary, Calgary, AB, Canada.,Department of Medical Physics, Tom Baker Cancer Centre, Calgary, AB, Canada.,Department of Radiation Oncology, University of Calgary, Calgary, AB, Canada
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