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Monte Carlo Commissioning of Low Energy Electron Radiotherapy Beams using NXEGS Software.

Both JA, Pawlicki T - Int J Med Sci (2004)

Bottom Line: Central axis depth-dose, primary axis and diagonal beam profiles, and output factors are the measurements necessary for commissioning of the code.We present a comparison of measured dose distributions with the distributions generated by NXEGS, using confidence limits on seven measures of error.We find that confidence limits are typically less than 3% or 3 mm, but increase with increasing source to surface distance (SSD) and depth at or beyond R(50).

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA.

ABSTRACT
This work is a report on the commissioning of low energy electron beams of a medical linear accelerator for Monte Carlo dose calculation using NXEGS software (NXEGS version 1.0.10.0, NX Medical Software, LLC). A unique feature of NXEGS is automated commissioning, a process whereby a combination of analytic and Monte Carlo methods generates beam models from dosimetric data collected in a water phantom. This study uses NXEGS to commission 6, 9, and 12 MeV electron beams of a Varian Clinac 2100C using three applicators with standard inserts. Central axis depth-dose, primary axis and diagonal beam profiles, and output factors are the measurements necessary for commissioning of the code. We present a comparison of measured dose distributions with the distributions generated by NXEGS, using confidence limits on seven measures of error. We find that confidence limits are typically less than 3% or 3 mm, but increase with increasing source to surface distance (SSD) and depth at or beyond R(50). We also investigate the dependence of NXEGS' performance on the size and composition of data used to commission the program, finding a weak dependence on number of dose profiles in the data set, but finding also that commissioning data need be measured at only two SSDs.

No MeSH data available.


Related in: MedlinePlus

Mean confidence limit for seven indicators. Circle, δ1,pdd; × , δ 2,pdd; +, RW50; *, Fr; square, δ 2; diamond, δ 3; triangle, δ 4. The bars are the uniformly weighted means of the means. SSD = 100 cm (left), 110 cm, 120 cm (right). The units of the ordinate are % or mm, as appropriate.
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Figure 3: Mean confidence limit for seven indicators. Circle, δ1,pdd; × , δ 2,pdd; +, RW50; *, Fr; square, δ 2; diamond, δ 3; triangle, δ 4. The bars are the uniformly weighted means of the means. SSD = 100 cm (left), 110 cm, 120 cm (right). The units of the ordinate are % or mm, as appropriate.

Mentions: Next, we supplement the picture presented by the ranking approach with an examination of mean NXEGS performance. Fig. 3 gives the mean confidence limits, resolved according to type only; that is, the means we report there are over beam and depth (if relevant). In particular, for the depth independent error measures, j=1,2, we plot


Monte Carlo Commissioning of Low Energy Electron Radiotherapy Beams using NXEGS Software.

Both JA, Pawlicki T - Int J Med Sci (2004)

Mean confidence limit for seven indicators. Circle, δ1,pdd; × , δ 2,pdd; +, RW50; *, Fr; square, δ 2; diamond, δ 3; triangle, δ 4. The bars are the uniformly weighted means of the means. SSD = 100 cm (left), 110 cm, 120 cm (right). The units of the ordinate are % or mm, as appropriate.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC1074715&req=5

Figure 3: Mean confidence limit for seven indicators. Circle, δ1,pdd; × , δ 2,pdd; +, RW50; *, Fr; square, δ 2; diamond, δ 3; triangle, δ 4. The bars are the uniformly weighted means of the means. SSD = 100 cm (left), 110 cm, 120 cm (right). The units of the ordinate are % or mm, as appropriate.
Mentions: Next, we supplement the picture presented by the ranking approach with an examination of mean NXEGS performance. Fig. 3 gives the mean confidence limits, resolved according to type only; that is, the means we report there are over beam and depth (if relevant). In particular, for the depth independent error measures, j=1,2, we plot

Bottom Line: Central axis depth-dose, primary axis and diagonal beam profiles, and output factors are the measurements necessary for commissioning of the code.We present a comparison of measured dose distributions with the distributions generated by NXEGS, using confidence limits on seven measures of error.We find that confidence limits are typically less than 3% or 3 mm, but increase with increasing source to surface distance (SSD) and depth at or beyond R(50).

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA.

ABSTRACT
This work is a report on the commissioning of low energy electron beams of a medical linear accelerator for Monte Carlo dose calculation using NXEGS software (NXEGS version 1.0.10.0, NX Medical Software, LLC). A unique feature of NXEGS is automated commissioning, a process whereby a combination of analytic and Monte Carlo methods generates beam models from dosimetric data collected in a water phantom. This study uses NXEGS to commission 6, 9, and 12 MeV electron beams of a Varian Clinac 2100C using three applicators with standard inserts. Central axis depth-dose, primary axis and diagonal beam profiles, and output factors are the measurements necessary for commissioning of the code. We present a comparison of measured dose distributions with the distributions generated by NXEGS, using confidence limits on seven measures of error. We find that confidence limits are typically less than 3% or 3 mm, but increase with increasing source to surface distance (SSD) and depth at or beyond R(50). We also investigate the dependence of NXEGS' performance on the size and composition of data used to commission the program, finding a weak dependence on number of dose profiles in the data set, but finding also that commissioning data need be measured at only two SSDs.

No MeSH data available.


Related in: MedlinePlus