Abstract P5-14-15: Discovery and validation of simple heart measurements to screen patients who will benefit from deep inspiration breath hold for left breast irradiation
Notice bibliographique
Résumé
Abstract Purpose: Deep inspiration breath hold (DIBH) using active breath control in left-sided breast irradiation (RT) can significantly reduce radiation dose to heart and coronary arteries in selected patients. At our institution, a cutoff of V50% >10cc is currently used to identify patients who require DIBH. This dose-volume cutoff requires generation of a radiation plan in order to select patients. The purpose of this study was to identify simple 2-D measurements of the heart at the time of CT simulation that can help screen patients for DIBH in order to streamline the process for left-sided breast RT. Methods: This study evaluated CT simulation scans from 50 left-sided breast cancer patients treated with tangent RT alone, where 50% of patients were treated with DIBH. On each CT dataset, a tangential line was drawn between the medial and lateral tattoos. The following heart measurements were recorded by a blinded observer at 2, 3, 4, and 5 cm below the tattoos: (1) maximal heart distance (MHD) perpendicular to this line and (2) heart length (HL) along this line. Predictive models were created using two strategies; (1) step wise approach utilizing the most significant factor and (2) principle component analysis. Using C-statistics, 3 cutoffs with the highest correlations with heart dose were determined from the model. These cutoffs were validated in a cohort of 100 consecutive patients treated from Jan-May 2012. Results: Data from 49 patients in the derivation cohort were analyzable. The HL at 2 cm had the strongest correlation with V50 (R2 = 0.45; p <0.0001). Other values that were associated with V50 were HL at 3 cm (R2 = 0.37; p = <0.0001), MHD at 2cm (R2 = 0.25; p = 0.0003), MHD at 3 cm (R2 = 0.23; p = 0.0006) and HL at 4 cm (R2 = 0.17, p = 0.0035). The predictive model using HL at 2 cm gave an adjusted R2 = 0.4385 (P<0.0001). Adding other variables into the predictive model did not improve the adjusted R2. The following 3 cutoffs for HL at 2 cm with respective (sensitivity; specificity) were identified: 3.92 cm (0.955; 0.48), 7.65 cm (0.32; 0.48), and 6.5 cm (0.5; 0.8). In the validation cohort, 22/100 had V50% > 10 cc. Validation of the 3 derived cutoffs for HL at 2 cm yielded the following sensitivities and specificities: 1.0 and 0.28 for 3.92 cm; 0.53 and 0.93 for 7.65 cm; 0.58 and 0.69 for 6.5 cm. Positive predictive value (PPV) and negative predictive value (NPV) were as follows: 3.92 cm (PPV = 0.25; NPV = 1.00). 7.65 cm (PPV = 0.63; NPV = 0.89), and 6.5cm (PPV = 0.30; NPV = 0.87). Conclusions: A simple 2-D heart measurement, heart length at 2 cm below the tattoos, had moderate correlation with the irradiated heart volume. Although HL at 2 cm did not have both high specificity and sensitivity to predict who would benefit from DIBH, cut-offs could be selected to maximize sensitivity (3.92 cm for sensitivity 1.0) or specificity (7.65 cm for specificity 0.93). For example, in departments that routinely acquire both free-breathing and DIBH CT simulation scans for all left-sided patients, a cutoff of 3.92cm would minimize the number of unnecessary DIBH scans. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-14-15.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,003 | 0,010 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,000 |
| Méta-épidémiologie (sens large) | 0,001 | 0,001 |
| Bibliométrie | 0,001 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,001 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,001 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».