Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0032285 (pneumonia)
 54,520 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The choice of the appropriate model and parameter set in determining the relation between the incidence of radiation pneumonitis and dose distribution in the lung is of great importance, especially in the case of breast radiotherapy where the observed incidence is fairly low. From our previous study based on 150 breast cancer patients, where the fits of dose-volume models to clinical data were estimated (Tsougos et al 2005 Evaluation of dose-response models and parameters predicting radiation induced pneumonitis using clinical data from breast cancer radiotherapy Phys. Med. Biol. 50 3535-54), one could get the impression that the relative seriality is significantly better than the LKB NTCP model. However, the estimation of the different NTCP models was based on their goodness-of-fit on clinical data, using various sets of published parameters from other groups, and this fact may provisionally justify the results. Hence, we sought to investigate further the LKB model, by applying different published parameter sets for the very same group of patients, in order to be able to compare the results. It was shown that, depending on the parameter set applied, the LKB model is able to predict the incidence of radiation pneumonitis with acceptable accuracy, especially when implemented on a sub-group of patients (120) receiving [see text]|EUD higher than 8 Gy. In conclusion, the goodness-of-fit of a certain radiobiological model on a given clinical case is closely related to the selection of the proper scoring criteria and parameter set as well as to the compatibility of the clinical case from which the data were derived.
 ...
PMID:Clinical validation of the LKB model and parameter sets for predicting radiation-induced pneumonitis from breast cancer radiotherapy. 1642 72

We therefore conclude that NTCP models, at least in some cases, are definitely tools not toys. However, like any good tool, they can be abused and in fact could lead to injury with misuse. In particular, we have pointed out that it is risky indeed to apply NTCP models to dose distributions which are very dissimilar to the dose distributions for which the NTCP model has been validated. While this warning is somewhat fuzzy, it is clear that more research needs to be done in this area. We believe that ultimately for NTCP models to be used routinely in treatment planning in a safe and effective way, the actual application will need to be closely related to the characteristics of the data sets and the uncertainties of the treatment parameters in the models under consideration. Another sign that NTCP models are becoming tools rather than toys is that there is often good agreement as to what constitutes a correct direction of improving the reduced risk for that particular complication endpoint. Thus, for example, mean dose to normal lung almost always comes out as being the most predictive or nearly most predictive factor in the analysis of radiation pneumonitis.
 ...
PMID:Image-based modeling of normal tissue complication probability for radiation therapy. 1823 19

Breast cancer patients are treated by a variety of options. Electron beams are utilised in the irradiation of the chest wall postmastectomy due to its dose distribution in the irradiated body. The objectives of this study were to determine the possibility of inducing lung fibrosis and pneumonitis during postmastectomy radiotherapy (PMRT) using electron beams. Electron beams with different energies and gantry angles were used for irradiating the chest wall in PMRT. The normal-tissue-complications-probability of the lung was evaluated. Three computer codes EGSnrc, XTING and DORES were used for simulating the beams and patients, generating dose-volume histograms and evaluating the dose response of the lung. NTCP increases with energy and with gantry angle. Below 15 MeV (which had given very high and unacceptable NTCP values), the largest value of NTCP of fibrosis was 0.036, for 12 MeV, gantry angle 60. The largest value of NTCP of radiation-induced pneumonitis was 0.044, for 12 MeV, gantry angle 60.
...
PMID:Risks of lung fibrosis and pneumonitis after postmastectomy electron radiotherapy. 2588 8

Abdominal compression has been shown to reduce the extent of lung tumor motion but the dosimetric impact of the approach is still in need of investigation. The current work analyzes the impact of various changes in PTV volume on key metrics of the final dose distribution to normal lung. To add clinical perspective, we also provide NTCP calculations for grade 2+ pneumonitis for each case. For a total of seventeen cases, the original ITV/PTV was reduced by systematically varied amounts and SBRT plans using dynamic conformal arc and VMAT techniques were created. DVH analysis for the normal lung comparing the original plan to the one with the ITV reduced by up to 10 mm shows that the average reduction of V5, V20 and mean lung dose is 3.8%, 2.0% and 1.1 Gy, respectively, for the conformal arc plans. Corresponding values for the VMAT plans were 3.9%, 1.9% and 1.2 Gy respectively. The mean NTCP drop for the conformal arc plans was 2.0% while it was 1.9% for the VMAT plans. These results suggest that abdominal compression has a modest impact on NTCP and on dosimetric parameters typically used to predict the risk of radiation pneumonitis in patients undergoing lung SBRT.
 ...
PMID:Dosimetric evaluation of abdominal compression as a method to reduce the incidence of radiation-induced pneumonitis in lung SBRT treatment. 2929 37