Limits...
Clinical implications in the use of the PBC algorithm versus the AAA by comparison of different NTCP models/parameters.

Bufacchi A, Nardiello B, Capparella R, Begnozzi L - Radiat Oncol (2013)

Bottom Line: The paired Student t-test was used for statistical comparison of all results obtained from the use of the two algorithms.Also NTCPAAA regarding the risk of radiation pneumonitis in the lung treatments was found to be lower than NTCPPBC for each of the eight sets of NTCP parameters; the maximum mean decrease was 4.5%.The NTCP is strongly affected by the wide-ranging values of radiobiological parameters.

View Article: PubMed Central - HTML - PubMed

Affiliation: Medical Physics, PioXI Clinic and UOC Medical Physics, S Giovanni Calibita Fatebenefratelli Hospital, Rome, Italy. ant.buf@tiscali.it

ABSTRACT

Purpose: Retrospective analysis of 3D clinical treatment plans to investigate qualitative, possible, clinical consequences of the use of PBC versus AAA.

Methods: The 3D dose distributions of 80 treatment plans at four different tumour sites, produced using PBC algorithm, were recalculated using AAA and the same number of monitor units provided by PBC and clinically delivered to each patient; the consequences of the difference on the dose-effect relations for normal tissue injury were studied by comparing different NTCP model/parameters extracted from a review of published studies. In this study the AAA dose calculation is considered as benchmark data. The paired Student t-test was used for statistical comparison of all results obtained from the use of the two algorithms.

Results: In the prostate plans, the AAA predicted lower NTCP value (NTCPAAA) for the risk of late rectal bleeding for each of the seven combinations of NTCP parameters, the maximum mean decrease was 2.2%. In the head-and-neck treatments, each combination of parameters used for the risk of xerostemia from irradiation of the parotid glands involved lower NTCPAAA, that varied from 12.8% (sd=3.0%) to 57.5% (sd=4.0%), while when the PBC algorithm was used the NTCPPBC's ranging was from 15.2% (sd=2.7%) to 63.8% (sd=3.8%), according the combination of parameters used; the differences were statistically significant. Also NTCPAAA regarding the risk of radiation pneumonitis in the lung treatments was found to be lower than NTCPPBC for each of the eight sets of NTCP parameters; the maximum mean decrease was 4.5%. A mean increase of 4.3% was found when the NTCPAAA was calculated by the parameters evaluated from dose distribution calculated by a convolution-superposition (CS) algorithm. A markedly different pattern was observed for the risk relating to the development of pneumonitis following breast treatments: the AAA predicted higher NTCP value. The mean NTCPAAA varied from 0.2% (sd = 0.1%) to 2.1% (sd = 0.3%), while the mean NTCPPBC varied from 0.1% (sd = 0.0%) to 1.8% (sd = 0.2%) depending on the chosen parameters set.

Conclusions: When the original PBC treatment plans were recalculated using AAA with the same number of monitor units provided by PBC, the NTCPAAA was lower than the NTCPPBC, except for the breast treatments. The NTCP is strongly affected by the wide-ranging values of radiobiological parameters.

Show MeSH

Related in: MedlinePlus

Comparison of NTCP for risk of developing pneumonitis following NSCLC treatment computed with the AAA (ordinate) and the PBC algorithm (abscissa) for NTCP models/parameters sets from Table2. Each symbol represents data of an individual patient. The dotted line indicates the line of identity.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3750611&req=5

Figure 3: Comparison of NTCP for risk of developing pneumonitis following NSCLC treatment computed with the AAA (ordinate) and the PBC algorithm (abscissa) for NTCP models/parameters sets from Table2. Each symbol represents data of an individual patient. The dotted line indicates the line of identity.

Mentions: For the normal lung dose parameters, the AAA predicted a mean reduction of 3.6 Gy for D2%, while the differences for Dmean and D20% were not statistically significant. D60% and V20% were found to be slightly higher when calculated with the AAA than had been predicted by the PBC algorithm. The resultant NTCPAAA values were lower than the NTCPPBC (FigureĀ 3). For both Seppenwoolde et al. [38] and Emami et al. [39] / Burman et al. [23] parameters, the comparison of NTCP values as calculated by two models, LKB and RS, involved higher values if the LKB model was applied.


Clinical implications in the use of the PBC algorithm versus the AAA by comparison of different NTCP models/parameters.

Bufacchi A, Nardiello B, Capparella R, Begnozzi L - Radiat Oncol (2013)

Comparison of NTCP for risk of developing pneumonitis following NSCLC treatment computed with the AAA (ordinate) and the PBC algorithm (abscissa) for NTCP models/parameters sets from Table2. Each symbol represents data of an individual patient. The dotted line indicates the line of identity.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3750611&req=5

Figure 3: Comparison of NTCP for risk of developing pneumonitis following NSCLC treatment computed with the AAA (ordinate) and the PBC algorithm (abscissa) for NTCP models/parameters sets from Table2. Each symbol represents data of an individual patient. The dotted line indicates the line of identity.
Mentions: For the normal lung dose parameters, the AAA predicted a mean reduction of 3.6 Gy for D2%, while the differences for Dmean and D20% were not statistically significant. D60% and V20% were found to be slightly higher when calculated with the AAA than had been predicted by the PBC algorithm. The resultant NTCPAAA values were lower than the NTCPPBC (FigureĀ 3). For both Seppenwoolde et al. [38] and Emami et al. [39] / Burman et al. [23] parameters, the comparison of NTCP values as calculated by two models, LKB and RS, involved higher values if the LKB model was applied.

Bottom Line: The paired Student t-test was used for statistical comparison of all results obtained from the use of the two algorithms.Also NTCPAAA regarding the risk of radiation pneumonitis in the lung treatments was found to be lower than NTCPPBC for each of the eight sets of NTCP parameters; the maximum mean decrease was 4.5%.The NTCP is strongly affected by the wide-ranging values of radiobiological parameters.

View Article: PubMed Central - HTML - PubMed

Affiliation: Medical Physics, PioXI Clinic and UOC Medical Physics, S Giovanni Calibita Fatebenefratelli Hospital, Rome, Italy. ant.buf@tiscali.it

ABSTRACT

Purpose: Retrospective analysis of 3D clinical treatment plans to investigate qualitative, possible, clinical consequences of the use of PBC versus AAA.

Methods: The 3D dose distributions of 80 treatment plans at four different tumour sites, produced using PBC algorithm, were recalculated using AAA and the same number of monitor units provided by PBC and clinically delivered to each patient; the consequences of the difference on the dose-effect relations for normal tissue injury were studied by comparing different NTCP model/parameters extracted from a review of published studies. In this study the AAA dose calculation is considered as benchmark data. The paired Student t-test was used for statistical comparison of all results obtained from the use of the two algorithms.

Results: In the prostate plans, the AAA predicted lower NTCP value (NTCPAAA) for the risk of late rectal bleeding for each of the seven combinations of NTCP parameters, the maximum mean decrease was 2.2%. In the head-and-neck treatments, each combination of parameters used for the risk of xerostemia from irradiation of the parotid glands involved lower NTCPAAA, that varied from 12.8% (sd=3.0%) to 57.5% (sd=4.0%), while when the PBC algorithm was used the NTCPPBC's ranging was from 15.2% (sd=2.7%) to 63.8% (sd=3.8%), according the combination of parameters used; the differences were statistically significant. Also NTCPAAA regarding the risk of radiation pneumonitis in the lung treatments was found to be lower than NTCPPBC for each of the eight sets of NTCP parameters; the maximum mean decrease was 4.5%. A mean increase of 4.3% was found when the NTCPAAA was calculated by the parameters evaluated from dose distribution calculated by a convolution-superposition (CS) algorithm. A markedly different pattern was observed for the risk relating to the development of pneumonitis following breast treatments: the AAA predicted higher NTCP value. The mean NTCPAAA varied from 0.2% (sd = 0.1%) to 2.1% (sd = 0.3%), while the mean NTCPPBC varied from 0.1% (sd = 0.0%) to 1.8% (sd = 0.2%) depending on the chosen parameters set.

Conclusions: When the original PBC treatment plans were recalculated using AAA with the same number of monitor units provided by PBC, the NTCPAAA was lower than the NTCPPBC, except for the breast treatments. The NTCP is strongly affected by the wide-ranging values of radiobiological parameters.

Show MeSH
Related in: MedlinePlus