Evaluation and performance of arccheck and film using gamma criteria in pre-treatment quality assurance of stereotactic ablative radiotherapy

Prabhakar, R; Tajaldeen, Abdulrahman; Taylor, David D.; Wanigaratne, D; Roozen, Karl; Geso, Moshi

doi:10.4103/jmp.jmp_132_16

Cited by 12 publications

(11 citation statements)

References 15 publications

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“…As for the gamma passing rates analysis, the average was 99.64% in the 3%/3 mm standard of general IMRT criteria, while the even more stringent 2%/2 mm criteria also had a value of 97.08% [16,17]. These results were superior to those obtained by previous studies, which found 98%±1% and >95% based on 3%/3 mm criteria [8,9].…”

Section: Discussioncontrasting

confidence: 57%

Dosimetric Evaluation of an Automatically Converted Radiation Therapy Plan between Radixact Machines

Lee

Kang

Kim

2020

Progress in Medical Physics

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We aim to evaluate the accuracy and effectiveness of an automatically converted radiation therapy plan between Radixact machines by comparing the original plan with the transferred plan. Methods:The study involved a total of 20 patients for each randomly selected treatment site who received radiation treatment with Radixact. We set up the cheese phantom (Gammex RMI, Middleton, WI, USA) with an Exradin A1SL ion chamber (Standard Imaging, Madison, WI, USA) and GAFCHROMIC EBT3 film (International Specialty Products, Wayne, NJ, USA) inserted. We used three methods to evaluate an automatically converted radiation therapy plan using the features of the Plan transfer. First, we evaluated and compared Planning target volume (PTV) coverage (homogeneity index, HI; conformity index, CI) and organs at risk (OAR) dose statistics. Second, we compared the absolute dose using an ion chamber. Lastly, we analyzed gamma passing rates using film.Results: Our results showed that the difference in PTV coverage was 1.72% in HI and 0.17% in CI, and majority of the difference in OAR was within 1% across all sites. The difference (%) in absolute dose values was averaging 0.74%. In addition, the gamma passing rate was 99.64% for 3%/3 mm and 97.08% for 2%/2 mm. Conclusions:The Plan transfer function can be reliably used in appropriate situations.

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Section: Discussioncontrasting

confidence: 57%

Dosimetric Evaluation of an Automatically Converted Radiation Therapy Plan between Radixact Machines

Lee

Kang

Kim

2020

Progress in Medical Physics

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“…However, a number of research publications showed how detector density can affect the GPR results. [27][28][29] Common in these publications is that it was expected that GPR would be greater by increasing detector density. It is of note, however, that increasing detector density of ArcCHECK by a factor of 2 achieves a similar detector density to the MapCHECK2.…”

Section: Sd Versus Hd Modementioning

confidence: 99%

Evaluation of parameters affecting gamma passing rate in patient‐specific QAs for multiple brain lesions IMRS treatments using ray‐station treatment planning system

Salari

Parsai

Shvydka

et al. 2021

J Applied Clin Med Phys

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Using intensity-modulated radiosurgery (IMRS) with single isocenter for the treatment of multiple brain lesions has gained acceptance in recent years. One of the challenges of this technique is conducting a patient-specific quality assurance (QA), involving accurate gamma passing rate (GPR) calculations for small and wide spread-out targets. We evaluated effects of parameters such as dose grid and energy on GPR using our clinical IMRS plans. Methods: Ten patients with total of 40 volumetric modulated arc therapy (VMAT) plans were created in Raystation (V.8A) treatment planning system (TPS) for the Varian Edge Linac using 6 and 10 flattening filter-free (FFF) beams and planned dose grids of 1 mm and 2 mm resulting in four plans with 6-10 targets per patient. All parameters and objectives except dose grid and energy were kept the same in all plans. Next, patient-specific QAs were measured evaluating GPR with 10% threshold, 3%/3 mm objective, and an acceptance criterion of 95%. Modulation factors (MF) and confidence intervals were calculated. Two modes of measurements, standard density (SD) and high density (HD), were used. Results: Generally, plans computed with 1 mm dose grid have higher GPRs than those with 2 mm dose grid for both energies used. The GPRs of 6 FFF plans were higher than those of 10 FFF plans. GPR showed no noticeable difference between HD and SD measurements. Negative correlation between MF and GPR was observed. The HD pass rates fall within the confidence interval of SD. Conclusion: Calculated dose grid should be less than or equal to one-third of distance to agreement, thus 1 mm planned dose grid is recommended to reduce artifacts in gamma calculation. GPR of SD and HD measurement modes is almost the same, which indicates that SD mode is clinically preferable for performing patient-specific QAs. According to our results, using 6 FFF beams with 1 mm planned dose grid is more accurate and reliable for dose calculation of IMRS plans.

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“…The dose at isocenter was measured by placing a calibrated ion chamber (PTW N30013) in the center of the ArcCHECK phantom. Although the ArcCHECK consists of small diode detectors (0.019 mm 3 ), their spacing may not provide a high enough resolution to be used for very small fields …”

Section: Methodsmentioning

confidence: 99%

Effect of beam configuration with inaccurate or incomplete small field output factors on the accuracy of treatment planning dose calculation

Sendani

Karimian²,

Mahdavi

et al. 2019

Medical Physics

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Purpose: To evaluate the effect of beam configuration with inaccurate or incomplete small field output factors on the accuracy of dose calculations in treatment planning systems. Methods: Output factors were measured using various detectors and for a range of field sizes. Three types of treatment machines were configured in two treatment planning systems. In the first (corrected) machine, the Exradin W1 scintillator was used to determine output factors. In the second (uncorrected) machine, the measured output factors by the A1SL ion chamber without considering output correction factors for small field sizes were utilized. In the third (clinical) machine, measured output factors by the Exradin W1 were used but not for field sizes smaller than 2 9 2 cm 2 . The dose computed by the anisotropic analytical algorithm (AAA), Acuros XB (AXB) and collapsed cone convolution/superposition (CCC) algorithms in the three machines were delivered using static (jaw-, MLC-, and jaw/MLC-defined), and composite [intensity modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT)] fields. The differences between measured and calculated dose values were analyzed. Results: For static fields, the percentage differences between measured and calculated doses by the three algorithms in three configured machines were <2% for field sizes larger than 2 9 2 cm 2 . In jaw-and jaw/MLC-defined fields smaller than 2 9 2 cm 2 , the corrected machine presented better agreement with measurement. Considering output correction factors in MLC-defined fields, among the three configured machines, the accuracy of calculation improved to within AE0.5%. For MLC-defined field size of 1 9 1 cm 2 , AXB showed the smallest percentage difference (1%). In IMRT and VMAT plans, the percentage differences between measured and calculated doses at the isocenter, as well as the gamma analysis of different plans, which include field sizes larger than 3 9 3 cm 2 , did not vary noticeably. For smaller field sizes, using the corrected machine influences dose calculation accuracy. Conclusion: Configuration with corrected output factors improves accuracy of dose calculation for static field sizes smaller than 2 9 2 cm 2 . For very small fields, the robustness of the dose calculation algorithm affects the accuracy of dose as well. In IMRT and VMAT plans, which include small subfields, the size of the jaw-defined field is an important factor and using corrected output factors increases dose calculation accuracy.

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Evaluation and performance of arccheck and film using gamma criteria in pre-treatment quality assurance of stereotactic ablative radiotherapy

Cited by 12 publications

References 15 publications

Dosimetric Evaluation of an Automatically Converted Radiation Therapy Plan between Radixact Machines

Dosimetric Evaluation of an Automatically Converted Radiation Therapy Plan between Radixact Machines

Evaluation of parameters affecting gamma passing rate in patient‐specific QAs for multiple brain lesions IMRS treatments using ray‐station treatment planning system

Effect of beam configuration with inaccurate or incomplete small field output factors on the accuracy of treatment planning dose calculation

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