On dose distribution comparison

Jiang, Steve B; Sharp, G; Neicu, T; Berbeco, R.; Flampouri, Stella; Bortfeld, Thomas

doi:10.1088/0031-9155/51/4/001

Cited by 59 publications

(40 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…162,164,167,[175][176][177][178] One example is shown in Fig. 4͑f͒, provided from Childress and Rosen 162 based on their normalized agreement test ͑NAT͒.…”

Section: Ivb4a Composite Toolmentioning

confidence: 99%

Dosimetry tools and techniques for IMRT

et al. 2011

View full text Add to dashboard Cite

Intensity modulated radiation therapy ͑IMRT͒ poses a number of challenges for properly measuring commissioning data and quality assurance ͑QA͒ radiation dose distributions. This report provides a comprehensive overview of how dosimeters, phantoms, and dose distribution analysis techniques should be used to support the commissioning and quality assurance requirements of an IMRT program. The proper applications of each dosimeter are described along with the limitations of each system. Point detectors, arrays, film, and electronic portal imagers are discussed with respect to their proper use, along with potential applications of 3D dosimetry. Regardless of the IMRT technique utilized, some situations require the use of multiple detectors for the acquisition of accurate commissioning data. The overall goal of this task group report is to provide a document that aids the physicist in the proper selection and use of the dosimetry tools available for IMRT QA and to provide a resource for physicists that describes dosimetry measurement techniques for purposes of IMRT commissioning and measurement-based characterization or verification of IMRT treatment plans. This report is not intended to provide a comprehensive review of commissioning and QA procedures for IMRT. Instead, this report focuses on the aspects of metrology, particularly the practical aspects of measurements that are unique to IMRT. The metrology of IMRT concerns the application of measurement instruments and their suitability, calibration, and quality control of measurements. Each of the dosimetry measurement tools has limitations that need to be considered when incorporating them into a commissioning process or a comprehensive QA program. For example, routine quality assurance procedures require the use of robust field dosimetry systems. These often exhibit limitations with respect to spatial resolution or energy response and need to themselves be commissioned against more established dosimeters. A chain of dosimeters, from secondary standards to field instruments, is established to assure the quantitative nature of the tests. This report is intended to describe the characteristics of the components of these systems; dosimeters, phantoms, and dose evaluation algorithms. This work is the report of AAPM Task Group 120.

show abstract

“…162,164,167,[175][176][177][178] One example is shown in Fig. 4͑f͒, provided from Childress and Rosen 162 based on their normalized agreement test ͑NAT͒.…”

Section: Ivb4a Composite Toolmentioning

confidence: 99%

Dosimetry tools and techniques for IMRT

et al. 2011

View full text Add to dashboard Cite

show abstract

“…34) is a similar metric to the more commonly used gamma. 35 In our implementation, NDD passing values were scaled to range from À1 to þ1, where positive/negative values mean the measured dose is higher/lower than the planned dose.…”

Section: Iic3 Analysismentioning

confidence: 99%

Commissioning and benchmarking a 3D dosimetry system for clinical use

et al. 2011

View full text Add to dashboard Cite

Purpose: A 3D dosimetry system is described which consists of two parts: a radiochromic plastic dosimeter PRESAGE V R (which responds to absorbed dose with a linear change in optical-density) and the Duke large-field-of-view optical-CT scanner (DLOS). The DLOS/PRESAGE system has recently been commissioned and benchmarked for clinical use and, in particular, for verification and commissioning of complex radiation treatments. Methods: DLOS commissioning involved determining the dynamic range, spatial resolution, noise, temporal, and other characteristics of the light source and imaging components. Benchmarking tests were performed on the combined DLOS/PRESAGE system to establish baseline dosimetric performance. The tests consisted of delivering simple radiation treatments to PRESAGE dosimeters, and comparing the measured 3D relative dose distributions with the known gold standard. The gold standard distribution was obtained from machine beam-data or the treatment planning system (TPS). All studies used standardized procedures to ensure consistency. Results: For commissioning, isotropic spatial resolution was submillimeter (MTF > 0.5 for frequencies of 1.5 lp/mm) and the dynamic range was $60 dB. Flood field uniformity was within 10% and stable after 45 min of warm-up. Stray-light is small, due to telecentricity, but even the residual can be removed through deconvolution by a point-spread-function. For benchmarking, the mean 3D passing NDD (normalized dose distribution) rate (3%, 3mm, 5% dose threshold) over the benchmark data sets was 97.3% 6 0.6% (range 96%-98%), which is on par with other planar dosimeters used in external beam radiation therapy indicating excellent agreement. Noise was low at <2% of maximum dose (4-12 Gy) for 2 mm reconstructions. The telecentric design was critical to enabling fast imaging with minimal stray-light artifacts. Conclusions: This work presents the first comprehensive benchmarking of a 3D dosimetry system for clinical use. The DLOS/PRESAGE benchmark tests show consistently good agreement to simple known distributions. The system produces accurate isotropic 2 mm dose data over clinical volumes (e.g., 16 cm diameter phantoms, 12 cm height), in under 15 min. It represents a uniquely useful and versatile new tool for commissioning and verification of complex therapy treatments.

show abstract

“…The range of exposures was chosen so that the dose distribution was in a region where the sensitivity was not linear. The images were compared using gamma analysis [18][19][20]. Gamma analysis works on two matrices, a field and a reference, by calculating the dose difference d, and the distance to agreement D, for each pixel in the dose and spatial axes respectively.…”

Section: Imrt Dose Distributionmentioning

confidence: 99%

Evaluation of EBT radiochromic film using a multiple exposure technique

Roozen

Kron

Haworth

et al. 2011

Australas Phys Eng Sci Med

View full text Add to dashboard Cite

Radiochromic film is a self developing two-dimensional dosimeter system that is widely used in radiotherapy. Since its development some 40 years ago many improvements have been made; however the sensitivity can vary across the film and a non-linear dose response remains. The former can be addressed using a double exposure technique; however this technique assumes that the response is linear so that the dose distribution is incorrectly measured. We are proposing the use of two homogenous exposures; one performed prior, the other after the irradiation to be measured. In this 'multiple exposure technique' (MET), the first homogenous exposure can be used to correct for variations in response in different parts of the film, while the second homogenous exposure allows correction for non-linearity of response with dose. The MET was tested with a 60° wedged field and an Intensity Modulated Radiation Therapy fluence map produced by a computerised treatment planning system. In the wedge field measurements, the MET profile showed agreement within 0.6 cGy for 80% of the field compared to ionisation chamber dose values. A comparison of a TPS generated fluence map dose distribution with one measured using conventionally calibrated EBT, and another measured with MET calibrated EBT, showed similar agreement. The MET would be particularly useful for the assessment of highly inhomogenous dose distributions with high maximum dose such as encountered in hypofractionated radiation therapy.

show abstract

On dose distribution comparison

Cited by 59 publications

References 31 publications

Dosimetry tools and techniques for IMRT

Dosimetry tools and techniques for IMRT

Commissioning and benchmarking a 3D dosimetry system for clinical use

Evaluation of EBT radiochromic film using a multiple exposure technique

Contact Info

Product

Resources

About