Using Deep Learning to Improve Early Diagnosis of Pneumonia in Underdeveloped Countries Kyler Larsen

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Using Deep Learning to Improve Early Diagnosis
of Pneumonia in Underdeveloped Countries
Kyler Larsen
November 2021
1 Introduction
Increasing efficiency and accuracy for the diagnosis of pneumonia can decrease
thousands of preventable deaths each year. Pneumonia is a common disease
in the community that can be easily treated with inexpensive oral antibiotics
administered by volunteer health care workers (Pneumonia 2021). However, if
there is any delay in diagnosis or treatment, the disease course can be very
serious and even deadly. Many of these diagnoses can be made through identifi-
cation of symptoms such as cough, fever, or an increased respiratory rate. Chest
x-ray is an inexpensive but vital component to diagnose pneumonia and to rule
out other diseases. Certain types of pneumonia, especially atypical pneumonia
such as Mycoplasma pneumoniae, can infect a person for weeks with no discern-
able symptoms. These types of pneumonia account for 10 to 40 percent of the
cases of community acquired pneumonia in the United States (Atypical 2021).
With this type of pneumonia it is even more important to use chest x-rays as
an effective tool for accurate diagnosis.
In underdeveloped countries, specifically in Sub-Saharan Africa and South-
east Asia, the death rate from pneumonia was almost 8-10 times the death rate
in the United States in 2017 (Dadonaite et al 2021). Although many countries
in Sub-Saharan Africa, such as Cameroon, receive medical equipment, including
x-ray machines, through donation services, up to 70% of the equipment is never
used (Piaggio et al 2009). One primary cause of this problem is the lack of doc-
tors and trained healthcare workers. In the Philippines, it was estimated that
85% of Filipino nurses were working overseas in Western countries, leading to
70% of Filipinos dying without medical attention (Finch 2013). In Sub-Saharan
Africa, a critical shortage of doctors and nurses amounting to 2.4 million per-
sonnel in the years 2000-2006, hampered the ability of many health programs
in place to detect and prevent chronic diseases (Naicker et al 2010). These
statistics show that a shortage of trained medical personnel in underdeveloped
countries causes delayed diagnoses or lack of proper treatment, leading to pos-
sible preventable deaths. This study will focus on evaluating a deep learning
model, specifically over how well it can detect pneumonia in chest x-rays, and
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arXiv:2210.05023v1 [eess.IV] 10 Oct 2022
adopting the model to become an affordable and accurate alternative that will
save many lives.
Previous studies have been conducted over the effectiveness of different AI
models in limiting pneumonia’s harmful effects. For example, various machine
learning models were evaluated on their accuracy in predicting severe pneumo-
nia, which would allow proper treatment before the harmful effects could take
place. The models evaluated in the study were the Support Vector Machine, Lo-
gistic Regression model, Random Forest Classifier, Naive Bayes, and AdaBoost.
Ultimately, the study concluded that the Random Forest Classifier performed
the best, due to its superior stability (Luo et al 2020). Another study evalu-
ated a deep learning transfer model, VGG-16, as to how well it could identify
pneumonia caused by COVID-19. The study also used chest x-ray analysis to
form the model’s diagnoses, but concluded that further improvements could be
made by adjusting hyperparameters and transfer learning combinations (M. D.
Hasan et al 2021). This study attempts to fill this gap by evaluating a basic
Convolutional Neural Network (CNN) by experimenting with hyperparameters
to achieve maximum metrics.
The purpose of this study was to evaluate the performance of a CNN model
given input in the form of chest x-rays. This study hypothesizes that the chang-
ing hyperparameters of the model can produce results equivalent to a trained
physician. The null hypothesis assumes the model would not improve through
training or would not achieve results similar to a physician. By testing various
hyperparameters and extracting results based on key metrics, conclusions can
be drawn as to how well the model performed (M. D. Hasan et al 2021). The
significance of this study is to provide information regarding the feasibility of
using a basic CNN model to diagnose accurately at point of care when there
is shortage of trained healthcare workers. By developing and evaluating such a
model, this study could save lives by improving efficiency and accuracy, as well
as saving money and time.
2 Methods
In this study, the first step was to organize the data set. The data set used in this
study is from Kaggle (Patel 2021), and features 6432 pre-classified images. This
dataset includes 3 separate categories: COVID-19 pneumonia, general pneu-
monia, and normal lung x-rays. For this study, only images from the general
pneumonia and normal lung x-rays were used, amounting to 2400 images with
1200 images from each classification. The data was then reshaped and aug-
mented to provide a variety of data and to eliminate the need for “perfect”
data. Augmentation included stretching certain pixels or rotating the image,
allowing the creation of extra data as each image could have multiple augmen-
tations done to it. The data was then split into 80% for training data and 20%
for testing data. The training data is the data used by the model to learn its
methods, while the testing data is used to evaluate the model’s accuracy.
A CNN works by receiving input in the form of an image. Then, through
2
a hierarchical system, the various layers of the CNN create a network that
resembles connected neurons, similar to the human brain. At each layer, an
activation function transforms the results of each layer into specific output.
The activation function used in this study is the Rectified Linear Activation
Unit (ReLU), which returns the sum of each node’s input, or 0 if the sum is less
than 0 (Brownlee 2021). The CNN then applies weights and flattens the output
before it is fed to a feed-forward neural network and backpropagation is applied
to every iteration of training. Over a series of these iterations, the model is able
to distinguish between important dominant features and less-valuable low-level
features (Brownlee 2021).
CNNs are valuable for identifying and classifying images, making it the ideal
model for this study. In this study, the CNN was defined as sequential, since it
only takes in one input and produces only one output, allowing for the addition
of multiple layers. An initial layer of 32 filters with ReLU activation was then
added, with a max pooling size of (2,2) to reduce output size. Then, additional
layers with 64 filters were added with ReLU activation before the output was
flattened. The amount of added layers is a tested variable, meaning it needs to
be non-specific. Dropout requirements were also set at 0.5 in order to reduce
overfitting, which is when the model memorizes the data set instead of forming
its own predictions. In this case, 50% of the neurons will be ignored during each
iteration, forcing the model to learn new patterns each time (Brownlee 2021).
Finally, the output is formatted and set to print loss function values, accuracy
metrics, specificity, and sensitivity.
For the testing phase of the model, experimentation was done through chang-
ing the model’s hyperparameters. The first parameter experimented with was
the number of extra layers added to the model, allowing more determinations
to be made at the expense of overfitting. Other parameters include the number
of epochs, or iterations, made by the model through the data set during each
training cycle, and the set sensitivity of the model, allowing for the maximum
sensitivity while still holding the other metrics constant. For each change to the
parameters, 5 models were trained and the average values for each specificity,
accuracy, precision, recall, and f1 score were taken to ensure accurate results.
The output displays the accuracy and specificity of the model after each model
is trained, as well as a graph depicting the trend of the accuracy over each
epoch.
3 Results
The primary focus of the trials in this study is to maximize sensitivity while
keeping specificity as high as possible. Sensitivity is defined by
3
摘要:

UsingDeepLearningtoImproveEarlyDiagnosisofPneumoniainUnderdevelopedCountriesKylerLarsenNovember20211IntroductionIncreasingeciencyandaccuracyforthediagnosisofpneumoniacandecreasethousandsofpreventabledeathseachyear.Pneumoniaisacommondiseaseinthecommunitythatcanbeeasilytreatedwithinexpensiveoralantib...

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