PubMed · 14395175
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P HILLEMAND, R VIGUIE. 1955-06-15. [Megaesophagus].. https://pubmed.ncbi.nlm.nih.gov/14395175/
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OBJECTIVE: To review our strategy for the treatment of patients with Type IV laryngotracheoesophageal cleft-a very rare congenital malformation. METHODS: Retrospective review of nine cases of Type IV laryngotracheoesophageal cleft managed between October 1994 and January 2004 at Great Ormond Street Hospital for Children, London. RESULTS: Three children were not operated upon (Group A) because of serious co-morbidity and parental decision not to opt for repair; they died at the ages of 2, 7 and 14 days, respectively. Six cases were repaired (Group B) at ages ranging from 2 to 53 days, all using an anterior cervico-thoracic approach. Two cases were operated upon using conventional ventilation, three using cardiopulmonary bypass and one using extracorporeal membrane oxygenation. There was no intra-operative mortality. The number of operative and diagnostic procedures varied from 4 to 37. Two operated cases expired at the ages of 11 days and 25 months; both were operated upon using cardiopulmonary bypass and had significant cardiac co-morbidity. Post-operative microlaryngoscopy and bronchoscopy showed dehiscence in the cleft repair ranging from 1mm to 2cm in five cases. This was observed at the distal end in three patients and just below the vocal cords in two cases. Three cases underwent further repair which was successful. The most recent case repaired using extracorporeal membrane oxygenation required less heparin when compared with those done on cardiopulmonary bypass and had the best post-operative result. Two patients were finally decannulated. The total duration of diagnostic and operative procedures ranged from 9 to 26h and 30min. The hospital stay in the operated cases varied from 9 days to 2 years 2 months 3 days, and their ICU stay ranged from 9 days to 10 months 7 days. All four of our patients with clefts which ended above the carina are alive after multiple repairs whereas all five cases with clefts extending all the way to the carina died (repair was attempted in two). CONCLUSION: Early diagnosis and repair are essential for successful treatment of Type IV laryngotracheoesophageal clefts. We believe it is best to repair this defect via an anterior cervico-thoracic approach, with or without a median sternotomy, and extracorporeal membrane oxygenation is now our preferred method of gas exchange during such repair. The longest Type IV clefts extending all the way to the carina have the worst prognosis. The decision to operate or not should be based upon the associated co-morbidity and fully informed parental choice, since treatment entails significant morbidity and mortality.
PURPOSE: To investigate methods of reporting and analyzing statistical uncertainties in doses to targets and normal tissues in Monte Carlo (MC)-based treatment planning. METHODS AND MATERIALS: Methods for quantifying statistical uncertainties in dose, such as uncertainty specification to specific dose points, or to volume-based regions, were analyzed in MC-based treatment planning for 5 lung cancer patients. The effect of statistical uncertainties on target and normal tissue dose indices was evaluated. The concept of uncertainty volume histograms for targets and organs at risk was examined, along with its utility, in conjunction with dose volume histograms, in assessing the acceptability of the statistical precision in dose distributions. The uncertainty evaluation tools were extended to four-dimensional planning for application on multiple instances of the patient geometry. All calculations were performed using the Dose Planning Method MC code. RESULTS: For targets, generalized equivalent uniform doses and mean target doses converged at 150 million simulated histories, corresponding to relative uncertainties of less than 2% in the mean target doses. For the normal lung tissue (a volume-effect organ), mean lung dose and normal tissue complication probability converged at 150 million histories despite the large range in the relative organ uncertainty volume histograms. For "serial" normal tissues such as the spinal cord, large fluctuations exist in point dose relative uncertainties. CONCLUSIONS: The tools presented here provide useful means for evaluating statistical precision in MC-based dose distributions. Tradeoffs between uncertainties in doses to targets, volume-effect organs, and "serial" normal tissues must be considered carefully in determining acceptable levels of statistical precision in MC-computed dose distributions.
PURPOSE: To evaluate whether increasing numbers of intensity-modulated radiation therapy (IMRT) fields enhance lung-tumor dose without additional predicted toxicity for difficult planning geometries. METHODS AND MATERIALS: Data from 8 previous three dimensional conformal radiation therapy (3D-CRT) patients with tumors located in various regions of each lung, but with planning target volumes (PTVs) overlapping part of the esophagus, were used as input. Four optimized-beamlet IMRT plans (1 plan that used the 3D-CRT beam arrangement and 3 plans with 3, 5, or 7 axial, but predominantly one-sided, fields) were compared. For IMRT, the equivalent uniform dose (EUD) in the whole PTV was optimized simultaneously with that in a reduced PTV exclusive of the esophagus. Normal-tissue complication probability-based costlets were used for the esophagus, heart, and lung. RESULTS: Overall, IMRT plans (optimized by use of EUD to judiciously allow relaxed PTV dose homogeneity) result in better minimum PTV isodose surface coverage and better average EUD values than does conformal planning; dose generally increases with the number of fields. Even 7-field plans do not significantly alter normal-lung mean-dose values or lung volumes that receive more than 13, 20, or 30 Gy. CONCLUSION: Optimized many-field IMRT plans can lead to escalated lung-tumor dose in the special case of esophagus overlapping PTV, without unacceptable alteration in the dose distribution to normal lung.