Investigation of Sub-Pitch Spatial Resolution for Pixelated CZT X-Ray Detector
Notice bibliographique
Résumé
As everyone knows, cancer is one of the greatest health enemies of mankind and became a major public health problem all over the world. Moreover, lung cancer is the most common global cancer leading to more than 1.3 million estimated deaths annually worldwide. Breast cancer is the most common cancer and the 2nd leading cause of death from in women in the US, Canada, and China. Therefore an instrument for the early diagnosis and monitoring of cancers in areas such as lung and breast is immensely important and necessary. The cadmium zinc telluride (CZT) semiconductor is a kind of novel radiation detector that can provide detailed information about spatial position. Also, the energy resulting from interactions between the radiation and the CZT material can also be assessed giving this type of detector added value in disease evaluation. A great deal of work on CZT detectors has been done for breast CT scanning. Furthermore, the CZT detector is also a potential solution for problems in lung cancer CT evaluation where the lack of energy information and high radiation exposure are less than ideal. Since sub-millimetre spatial resolution is required for post-contrast thoracic CT assessment, and $100~\mu m$ or better is critical for breast CT, the investigation of spatial resolution for CZT detectors is essential. In this thesis, the interactions within CZT detectors were analyzed. The influence of different configurations, including adjustment of anode size, gap size, detector thickness and bias voltage, were discussed. Next the methods to evaluate two kinds of signals (collected and transit signals), are provided in Chapter~2. In Chapter~3, an intensity difference method and an intensity ratio method for estimating the sub-pitch spatial resolution were described in detail. Finally, a detector spatial resolution between $10~\mu m$ and $20~\mu m$ was achieved using the collecting signal intensities ratio method and a $4~mm$ thick CZT detector with gap size of $g=50~\mu m$ and bias voltage of $V=300V$. Future work should focus on the contributions from characteristic X-rays emitted from cadmium and tellurium atoms. Also, the work presented was only on pixelated arrays and further assessment of cross-strip electrode detectors could also be of benefit. Lastly based on simulations done in this thesis all photons were assumed to strike the cathode at 90 degrees. Future work should also include non-orthogonal directions for photons.
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,000 |
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 tête enseignante, 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 ».