γ+ index: A new evaluation parameter for quantitative quality assurance

Stathakis, Sotirios; Mavroidis, Panayiotis; Shi, Chengyu; Xu, Jindong; Kauweloa, K.; Papanikolaou, Niko

doi:10.1016/j.cmpb.2014.01.005

Cited by 6 publications

(7 citation statements)

References 30 publications

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“…The AAPM TG-119 report [14] recommended action levels of 88% and 90% for composite and per field gamma passing rate GP (%) analysis, respectively. However, it only determines the ratio of points out of tolerance without giving any information about the spatial location of points that the dose deviated from in the origin plan, including the volumetric dose deviation for planned target volumes (PTVs) and organ at risk (OAR) of the patient [15]. Some of the recent research showed that γ passing rates of per beam planar IMRT QA did not predict clinically relevant dose errors [16], owing to a lack of correlation between the gamma passing rates (GP (%)and the volumetric dose errors in the anatomic regions-of-interest [17, 18].…”

Section: Introductionmentioning

confidence: 99%

Retrospective dosimetry study of intensity-modulated radiation therapy for nasopharyngeal carcinoma: measurement-guided dose reconstruction and analysis

et al. 2018

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BackgroundConventional phantom-based planar dosimetry (2D-PBD) quality assurance (QA) using gamma pass rate (GP (%)) is inadequate to reflect clinically relevant dose error in intensity-modulated radiation therapy (IMRT), owing to a lack of information regarding patient anatomy and volumetric dose distribution. This study aimed to evaluate the dose distribution accuracy of IMRT delivery for nasopharyngeal carcinoma (NPC), which passed the 2D-PBD verification, using a measurement-guided 3D dose reconstruction (3D-MGR) method.MethodsRadiation treatment plans of 30 NPC cases and their pre-treatment 2D-PBD data were analyzed. 3D dose distribution was reconstructed on patient computed tomography (CT) images using the 3DVH software and compared to the treatment plans. Global and organ-specific dose GP (%), and dose-volume histogram (DVH) deviation of each structure was evaluated. Interdependency between GP (%) and the deviation of the volumetric dose was studied through correlation analysis.ResultsThe 3D-MGR achieved global GP (%) similar to conventional 2D-PBD in the same criteria. However, structure-specific GP (%) significantly decreased under stricter criteria, including the planning target volume (PTV). The average deviation of all inspected dose volumes (DV) and volumetric dose (VD) parameters ranged from − 2.93% to 1.17%, with the largest negative deviation in V100% of the PTVnx of − 15.66% and positive deviation in D1cc of the spinal cord of 6.66%. There was no significant correlation between global GP (%) of 2D-PBD or 3D-MGR and the deviation of the most volumetric dosimetry parameters (DV or VD), when the Pearson’s coefficient value of 0.8 was used for correlation evaluation.ConclusionEven upon passing the pre-treatment phantom based dosimetric QA, there could still be risk of dose error like under-dose in PTVnx and overdose in critical structures. Measurement-guided 3D volumetric dosimetry QA is recommended as the more clinically efficient verification for the complicated NPC IMRT.Electronic supplementary materialThe online version of this article (10.1186/s13014-018-0993-2) contains supplementary material, which is available to authorized users.

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Section: Introductionmentioning

confidence: 99%

Retrospective dosimetry study of intensity-modulated radiation therapy for nasopharyngeal carcinoma: measurement-guided dose reconstruction and analysis

et al. 2018

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“…Recently, several groups have suggested methods of evaluating IMRT QA results through radiobiological as well as physical considerations [ 9 , 10 ]. Sumida et al proposed a method that introduced radiobiological effects by means of TCP and NTCP based on the application of the Niemierko model to physical gamma analysis [ 9 ].…”

Section: Discussionmentioning

confidence: 99%

“…Recently, an alternative NTCP dataset based on 3D dose–volume information for various organs has been made available (QUANTEC) [ 26 ]. Stathakis et al suggested a new index called gamma plus (by introducing radiobiological information to the gamma index) and applied it to a lung cancer IMRT [ 10 ]. In this method, the radiobiological effect was based on the RS model, which was based on QUANTEC, and the planar dose distributions were evaluated using the biologically effective uniform dose.…”

Section: Discussionmentioning

confidence: 99%

“…The QA evaluation methods and their reactions are based only on physical terms and do not consider radiobiological terms such as tumor control probability (TCP) and normal tissue complication probability (NTCP). These problems imply that radiobiological considerations should be introduced to IMRT QA in order to evaluate its results [ 9 , 10 ].…”

Section: Introductionmentioning

confidence: 99%

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Three-dimensional dose prediction and validation with the radiobiological gamma index based on a relative seriality model for head-and-neck IMRT

Hamatani

Sumida

Takahashi

et al. 2017

Journal of Radiation Research

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This study proposes a quality assurance (QA) method incorporating radiobiological factors based on the QUANTEC-determined tumor control probability and the normal tissue complication probability (NTCP) of head-and-neck intensity-modulated radiation therapy (HN-IMRT). Per-beam measurements were conducted for 20 cases using a 2D detector array. Three-dimensional predicted dose distributions within targets and organs at risk were reconstructed based on the per-beam QA results derived from differences between planned and measured doses. Under the predicted dose distributions, the differences between the physical and radiobiological gamma indices (PGI and RGI, respectively) based on the relative seriality (RS) model were evaluated. The NTCP values in the RS and Niemierko models were compared. The dose covers 98% (D98%) of the clinical target volume (CTV) decreased by 3.2% (P < 0.001), and the mean dose of the ipsilateral parotid increased by 6.3% (P < 0.001) compared with the original dose. RGI passing rates in the CTV and brain stem were greater than PGI ones by 5.8% (P < 0.001) and 2.0% (P < 0.001), respectively. The RS model’s average NTCP values for the ipsilateral and contralateral parotids under the original dose were smaller than those of the Niemierko model by 9.0% (P < 0.001) and 7.0% (P < 0.001), respectively. The 3D predicted dose evaluation with RGI based on the RS model was introduced for QA of HN-IMRT, leading to dose evaluation for each organ with consideration of the radiobiological effect. This method constitutes a rational way to perform QA of HN-IMRT in clinical practice.

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“…Trata-se de um método que compara de maneira quantitativa duas distribuições de dose ponto a ponto(STATHAKIS et al, 2014), onde uma distribuição é utilizada como referência e a outra será avaliada. Esse método foi primeiramente proposto por Low e colaboradores(LOW et al, 1998) e utiliza dois critérios nas comparações: um com relação à distância de concordância entre o mesmo valor de dose das duas distribuições e outro…”

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Avaliação de parâmetros dosimétricos de fontes de braquiterapia utilizando simulação Monte Carlo e dosimetria gel polimérica

Silva¹

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Agradecimentos À Deus pelo presente da vida, por me conduzir diariamente. À minha orientadora, Profa. Dra. Patrícia Nicolucci. Obrigada por todo ensinamento, discussões, reflexões e pela paciência. O seu profissionalismo, a sua dedicação e a sua competência, fizeram a diferença nesse trabalho e na minha vida, assim como na vida das pessoas que tem a oportunidade de conhecê-la. Obrigada por muitas vezes gastar dias e dias me explicando aquilo que eu já deveria saber... Quanta humildade e quanta sabedoria em uma pessoa só. Você é um exemplo pra todos nós. Obrigada, também, pela amizade, pelos seus conselhos. Foi uma grande alegria e uma grande honra ter a oportunidade de ser sua aluna. Aos meus pais, Luiz Mário Ramos da Silva e Rosilene Ap. Quevedo da Silva, pelo amor incondicional e todo esforço. Chegar até aqui não foi fácil e vocês estavam comigo, sempre. Sem vocês nada disso também seria possível. Ao meu irmão Renan, aos meus tios, primos e avós, que sempre estavam de braços abertos para me receber quando voltava pra casa, sempre dispostos a me apoiar. Obrigada pelo carinho de sempre. Em especial ao meu avô, Frederico Quevedo, que mesmo não estando mais presente fisicamente, tenho plena certeza que está comigo onde quer que eu vá. Que falta o senhor faz! À Dra. Cassiana Viccari Sacilotto, Profa. Dra. Thatiane Alves Pianoschi Alva e Prof. Dr. Mirko Alva. Obrigada pela amizade, por toda ajuda, pelo carinho, pelos conselhos, pelo apoio de sempre. Amigos como vocês não cruzam a nossa vida duas vezes e eu tive a sorte de encontrá-los! Mesmo que a vida possa nos afastar, vou levá-los para sempre comigo.

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γ+ index: A new evaluation parameter for quantitative quality assurance

Cited by 6 publications

References 30 publications

Retrospective dosimetry study of intensity-modulated radiation therapy for nasopharyngeal carcinoma: measurement-guided dose reconstruction and analysis

Retrospective dosimetry study of intensity-modulated radiation therapy for nasopharyngeal carcinoma: measurement-guided dose reconstruction and analysis

Three-dimensional dose prediction and validation with the radiobiological gamma index based on a relative seriality model for head-and-neck IMRT

Avaliação de parâmetros dosimétricos de fontes de braquiterapia utilizando simulação Monte Carlo e dosimetria gel polimérica

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