面具感知变压器具有结构不变损失,用于CT转换
Wenting Chen1, Wei Zhao2, Zhen Chen1
1Department of Electrical Engineering, City University of Hong Kong, Hong Kong Special Administrative Region of China.
Medical image analysis
|May 24, 2024
概括
这项研究引入了一个面具意识变压器 (MAFormer),用于将普通CT扫描转化为多相增强计算机断层扫描 (MPECT) 图像. 这种新方法利用临床领域的知识来改善肝病变检测和患者安全.
科学领域:
- 医疗成像医学成像
- 人工智能的人工智能
背景情况:
- 多相增强计算机断层扫描 (MPECT) 对于检测肝脏病变至关重要,但具有过敏风险.
- 目前的CT翻译方法忽视了有价值的临床领域知识,限制了它们的有效性.
研究的目的:
- 开发一种自动CT翻译方法,结合临床领域的知识,以改善MPECT图像生成.
- 为了提高肝损伤的检测,并减少与MPECT检查相关的患者过敏风险.
主要方法:
- 提出了一个面具意识变压器 (MAFormer) 模型用于CT翻译.
- 引入了一个面具估计器来预测减法图像,突出显示对比度增强区域.
- 开发了基于面具意识变压器的规范化 (MATNorm),用于整合减法图像和捕获依赖关系.
- 实施结构不变损失,以在翻译的CT图像中保存生物结构.
主要成果:
- 该MAFormer模型有效地将普通CT转换为MPECT图像.
- 该方法在现有的最先进的CT翻译技术上表现出优越性.
- 实验结果验证了结合临床领域知识的有效性.
结论:
- MAFormer代表了医学成像自动CT翻译的重大进步.
- 这种方法有望提高肝病诊断的诊断准确度和患者安全.
相关概念视频
Types Of Transformers
Transformers can provide desired voltages to a circuit by modifying the number of turns in the secondary windings.
If the ratio of the number of turns in the secondary winding to that of the primary winding is greater than one, then the transformer is said to be a step-up transformer. In a step-up transformer, the voltage at the secondary winding is greater than the voltage applied at the primary winding.
However, if this ratio is less than one, the transformer is said to be a step-down...
If the ratio of the number of turns in the secondary winding to that of the primary winding is greater than one, then the transformer is said to be a step-up transformer. In a step-up transformer, the voltage at the secondary winding is greater than the voltage applied at the primary winding.
However, if this ratio is less than one, the transformer is said to be a step-down...
Energy Losses in Transformers
In an ideal transformer, it is assumed that there are no energy losses, and, hence, all the power at the primary winding is transferred to the secondary winding. However, in reality, the transformers always have some energy losses, and, hence, the output power obtained at the secondary winding is less than the input power at the primary winding due to energy losses.
There are four main reasons for energy losses in transformers.
The first cause can be the high resistance of the copper windings...
There are four main reasons for energy losses in transformers.
The first cause can be the high resistance of the copper windings...
Reducing Line Loss
In a three-phase circuit, line loss is an indicator of energy dissipated as heat due to the resistance of transmission lines. To address this, incorporating transformers into the system—a step-up transformer at the source and a step-down transformer at the load—is a strategic solution. Two three-phase transformers are introduced to improve this.
With a step-up transformer at the source, the voltage is increased, thereby reducing the current in the transmission lines since power loss in...
With a step-up transformer at the source, the voltage is increased, thereby reducing the current in the transmission lines since power loss in...
Equivalent Circuits for Practical Transformers
The practical equivalent circuits of single-phase two-winding transformers exhibit significant deviations from their idealized versions due to the inherent properties of winding resistance and finite core permeability. These properties result in real and reactive power losses, affecting the transformer's performance. Understanding these deviations is crucial for designing more efficient transformers.
In a practical transformer, each winding exhibits resistance and leakage reactance. The winding...
In a practical transformer, each winding exhibits resistance and leakage reactance. The winding...
Transformers with Off-Nominal Turns Ratios
In scenarios involving parallel transformers with disparate ratings, developing per-unit models requires accommodating off-nominal turns ratios. This situation arises when the selected base voltages are not proportional to the transformer’s voltage ratings. Consider a transformer where the rated voltages are related by the term a. If the chosen voltage bases satisfy a relationship involving term b, term c is defined as the ratio of these bases. This ratio is then substituted into the rated...
Per-Unit Sequence Models
An ideal Y-Y transformer, grounded through neutral impedances, displays per-unit sequence networks akin to those of a single-phase ideal transformer when subjected to balanced positive- or negative-sequence currents. These currents do not produce neutral currents, and their associated voltage drops.
Zero-sequence currents, which are identical in magnitude and phase, generate a neutral current, resulting in voltage drops across the neutral impedance and the low-voltage winding. If the...
Zero-sequence currents, which are identical in magnitude and phase, generate a neutral current, resulting in voltage drops across the neutral impedance and the low-voltage winding. If the...


