diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..efe9e38
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,14 @@
+# qmake / build artifacts
+source/Makefile*
+source/.qmake.stash
+source/*.o
+source/moc_*.cpp
+source/moc_*.o
+source/moc_predefs.h
+source/ui_*.h
+source/object_script.*
+*.app/
+3ddose_tools
+3ddose_tools.exe
+*.pro.user
+.DS_Store
diff --git a/README.md b/README.md
index f423f9f..d5424b9 100644
--- a/README.md
+++ b/README.md
@@ -1,31 +1,39 @@
-# Compiling information for those with Qt5 dev tools installed:
+# 3ddose_tools
 
-To compile, go to the source directory and invoke the following 2 commands:
+3ddose file analysis tool (CLRP). Requires **Qt 6**.
+
+## Build
+
+With Qt 6 development tools installed:
 
 ```
-3ddose_tools/source> qmake
-3ddose_tools/source> make
+cd 3ddose_tools/source
+qmake6   # or: qmake  (if it points at Qt 6)
+make
 ```
 
-and an executable should appear in the parent directory.
-
-# How to install from scratch
+The executable appears in the parent directory as `3ddose_tools`.
 
-If you don't have Qt5 installed, then you will need to do it manually, or through a package manager (like apt-get in Ubuntu).  Here's an Ubuntu example:
+### macOS (Homebrew)
 
 ```
-sudo apt-get install qtbase5-dev qt5-qmake qtbase5-dev-tools
+brew install qt
+cd 3ddose_tools/source
+/opt/homebrew/opt/qt/bin/qmake
+make
 ```
 
-Navigate to the directory you intend to install in, and invoke the following commands:
+### Ubuntu / Debian
 
 ```
-> git clone https://github.com/MartinMartinov/3ddose_tools
-> cd 3ddose_tools/source/
-3ddose_tools/source> qmake
-3ddose_tools/source> make
-3ddose_tools/source> cd ..
-3ddose_tools> ./3ddose_tools
+sudo apt-get install qt6-base-dev qt6-base-dev-tools
+cd 3ddose_tools/source
+qmake6
+make
 ```
 
-and you should launch 3ddose_tools.
+## Clone
+
+```
+git clone https://github.com/clrp-code/3ddose_tools
+```
diff --git a/source/interface.cpp b/source/interface.cpp
index 53086c3..ad2e88c 100644
--- a/source/interface.cpp
+++ b/source/interface.cpp
@@ -182,7 +182,7 @@ Interface::~Interface() {
 *******************************************************************************/
 void Interface::addDose() {
     QStringList paths =
-        QFileDialog::getOpenFileNames(0, tr("Load Files"), 0,
+        QFileDialog::getOpenFileNames(nullptr, tr("Load Files"), QString(),
                                       tr("3ddose (*.3ddose *.b3ddose)"));
 
     // Set up the progress bar
@@ -289,7 +289,7 @@ void Interface::outputDose() {
     for (int i = 0; i < data->size(); i++)
         if (doseList->selectedItems().contains(doseList->item(i))) {
             path =
-                QFileDialog::getSaveFileName(0, tr("Save File ") +
+                QFileDialog::getSaveFileName(nullptr, tr("Save File ") +
                                              doseList->item(i)->text(),
                                              doseList->item(i)->text(),
                                              tr("3ddose (*.3ddose *.b3ddose)"));
@@ -356,10 +356,10 @@ void Interface::doseAtPoints() {
     QFile *file;
     QTextStream *input;
 
-    QString path = QFileDialog::getOpenFileName(0, tr("Open File"), 0,
+    QString path = QFileDialog::getOpenFileName(nullptr, tr("Open File"), QString(),
                    tr("Points File (*.txt)"));
 
-    if (path == 0) {
+    if (path.isEmpty()) {
         return;
     }
 
@@ -483,9 +483,9 @@ void Interface::doseAtPoints() {
                 }
 			}
 
-    path = QFileDialog::getSaveFileName(0, tr("Save File"), 0,
+    path = QFileDialog::getSaveFileName(nullptr, tr("Save File"), QString(),
                                         tr("Dose at Points (*.txt)"));
-    if (path == 0) {
+    if (path.isEmpty()) {
         return;
     }
 
@@ -509,7 +509,7 @@ void Interface::doseAtPoints() {
                     s = s.left(30);
                 }
 
-                *input << qSetFieldWidth(30) << center << s
+                *input << qSetFieldWidth(30) << Qt::center << s
                        << qSetFieldWidth(0) << "|";
                 if (i != data->size()-1) {
                     *input << "|";
@@ -574,10 +574,10 @@ void Interface::rebinBounds() {
     QFile *file;
     QTextStream *input;
 
-    QString path = QFileDialog::getOpenFileName(0, tr("Open File"), 0,
+    QString path = QFileDialog::getOpenFileName(nullptr, tr("Open File"), QString(),
                    tr("Boundaries File (*.txt)"));
 
-    if (path == 0) {
+    if (path.isEmpty()) {
         return;
     }
 
@@ -1226,7 +1226,7 @@ void Interface::plotAxis() {
             }
 		}
 
-    QString path = QFileDialog::getSaveFileName(0, tr("Save File "), 0,
+    QString path = QFileDialog::getSaveFileName(nullptr, tr("Save File "), QString(),
                    tr("Comma Separated Values ") +
                    tr("(*.csv)"));
     if (path == "") {
@@ -1246,12 +1246,10 @@ void Interface::plotAxis() {
         QString name = path.section("/",path.count("/"),path.count("/"));
         name = name.left(name.size() - (path.endsWith(tr(".csv"))?4:5));
         *input << name << "\n";
-        int n = 0;
         for (int i = 0; i < data->size(); i++)
             if (doseList->selectedItems().contains(doseList->item(i))) {
                 *input << doseList->item(i)->text() << "\n";
                 *input << (*data)[i]->plot(axis, h, u, j, k);
-                n++;
             }
 
         *input << "\n";
@@ -1262,7 +1260,7 @@ void Interface::plotAxis() {
 
 void Interface::selectEGSFile() {
     QString path =
-        QFileDialog::getOpenFileName(0, tr("Open File"), 0,
+        QFileDialog::getOpenFileName(nullptr, tr("Open File"), QString(),
                                      tr("EGSphant File (*.egsphant *.begsphant)"));
     if (path == "") {
         return;
@@ -1304,7 +1302,7 @@ void Interface::selectEGSFile() {
 
 void Interface::selectStatEGSFile() {
     QString path =
-        QFileDialog::getOpenFileName(0, tr("Open File"), 0,
+        QFileDialog::getOpenFileName(nullptr, tr("Open File"), QString(),
                                      tr("EGSphant File (*.egsphant *.begsphant)"));
     if (path == "") {
         return;
@@ -1387,7 +1385,7 @@ void Interface::plotLine() {
             }
 		}
 
-    QString path = QFileDialog::getSaveFileName(0, tr("Save File "), 0,
+    QString path = QFileDialog::getSaveFileName(nullptr, tr("Save File "), QString(),
                    tr("Comma Separated Values ") +
                    tr("(*.csv)"));
     if (path == "") {
@@ -1414,7 +1412,6 @@ void Interface::plotLine() {
         name = name.left(name.size() - (path.endsWith(tr(".csv"))?4:5));
         *input << name << "\n";
 
-        int n = 0;
         double val = 0, err = 0;
         for (int i = 0; i < data->size(); i++)
             if (doseList->selectedItems().contains(doseList->item(i))) {
@@ -1447,7 +1444,6 @@ void Interface::plotLine() {
                     *input << QString::number(val*err, 'E', 6);
                     *input << "\n";
                 }
-                n++;
             }
 
         *input << "\n";
@@ -1457,7 +1453,7 @@ void Interface::plotLine() {
 }
 
 void Interface::plotDVH() {
-    QString path = QFileDialog::getSaveFileName(0, tr("Save File "), 0,
+    QString path = QFileDialog::getSaveFileName(nullptr, tr("Save File "), QString(),
                    tr("Comma Separated Values ") +
                    tr("(*.csv)"));
     if (path == "") {
@@ -1514,7 +1510,6 @@ void Interface::plotDVH() {
         name = name.left(name.size() - (path.endsWith(tr(".csv"))?4:5));
         *input << name << "\n";
 
-        int n = 0;
         for (int i = 0; i < data->size(); i++)
             if (doseList->selectedItems().contains(doseList->item(i))) {
                 *input << doseList->item(i)->text() << "\n";
@@ -1560,7 +1555,6 @@ void Interface::plotDVH() {
                                                &eAvg, &err, &maxErr, &totVol,
                                                &nVox, &Dx, &Vx);
 
-                n++;
             }
 
         *input << "\n";
@@ -1569,9 +1563,9 @@ void Interface::plotDVH() {
     delete file;
 
     if (dvhExtra->isChecked()) {
-        QString path2 = QFileDialog::getSaveFileName(0, tr("Save File"), 0,
+        QString path2 = QFileDialog::getSaveFileName(nullptr, tr("Save File"), QString(),
                         tr("Additional Statistics (*.txt)"));
-        if (path2 == 0) {
+        if (path2.isEmpty()) {
             return;
         }
 
@@ -1629,7 +1623,7 @@ void Interface::plotDVHReg() {
             }
         }
 
-    QString path = QFileDialog::getSaveFileName(0, tr("Save File "), 0,
+    QString path = QFileDialog::getSaveFileName(nullptr, tr("Save File "), QString(),
                    tr("Comma Separated Values ") +
                    tr("(*.csv)"));
     if (path == "") {
@@ -1684,7 +1678,6 @@ void Interface::plotDVHReg() {
         name = name.left(name.size() - (path.endsWith(tr(".csv"))?4:5));
         *input << name << "\n";
 
-        int n = 0;
         for (int i = 0; i < data->size(); i++)
             if (doseList->selectedItems().contains(doseList->item(i))) {
                 xi = dvhxi->getText().toDouble();
@@ -1737,7 +1730,6 @@ void Interface::plotDVHReg() {
                                                &avg, &eAvg, &err, &maxErr,
                                                &totVol, &nVox, &Dx, &Vx);
 
-                n++;
             }
 
         *input << "\n";
@@ -1746,9 +1738,9 @@ void Interface::plotDVHReg() {
     delete file;
 
     if (dvhExtra->isChecked()) {
-        QString path2 = QFileDialog::getSaveFileName(0, tr("Save File"), 0,
+        QString path2 = QFileDialog::getSaveFileName(nullptr, tr("Save File"), QString(),
                         tr("Additional Statistics (*.txt)"));
-        if (path2 == 0) {
+        if (path2.isEmpty()) {
             return;
         }
 
@@ -1789,7 +1781,7 @@ void Interface::plotDVHMed() {
             }
         }
 
-    QString path = QFileDialog::getSaveFileName(0, tr("Save File "), 0,
+    QString path = QFileDialog::getSaveFileName(nullptr, tr("Save File "), QString(),
                    tr("Comma Separated Values ") +
                    tr("(*.csv)"));
     if (path == "") {
@@ -1844,7 +1836,6 @@ void Interface::plotDVHMed() {
         name = name.left(name.size() - (path.endsWith(tr(".csv"))?4:5));
         *input << name << "\n";
 
-        int n = 0;
         for (int i = 0; i < data->size(); i++)
             if (doseList->selectedItems().contains(doseList->item(i))) {
                 *input << doseList->item(i)->text() << "\n";
@@ -1876,7 +1867,6 @@ void Interface::plotDVHMed() {
                                                &avg, &eAvg, &err, &maxErr,
                                                &totVol, &nVox, &Dx, &Vx);
 
-                n++;
             }
 
         *input << "\n";
@@ -1885,9 +1875,9 @@ void Interface::plotDVHMed() {
     delete file;
 
     if (dvhExtra->isChecked()) {
-        QString path2 = QFileDialog::getSaveFileName(0, tr("Save File"), 0,
+        QString path2 = QFileDialog::getSaveFileName(nullptr, tr("Save File"), QString(),
                         tr("Additional Statistics (*.txt)"));
-        if (path2 == 0) {
+        if (path2.isEmpty()) {
             return;
         }
 
@@ -1949,7 +1939,7 @@ void Interface::plot() {
 // The 3 stat functions for different region cases need to be combined,
 // the current state is embarrassingly bad
 void Interface::statH(Dose *comp) {
-    QString path = QFileDialog::getSaveFileName(0, tr("Save File "), 0,
+    QString path = QFileDialog::getSaveFileName(nullptr, tr("Save File "), QString(),
                    tr("Comma Separated Values ") +
                    tr("(*.csv)"));
     if (path == "") {
@@ -2101,7 +2091,6 @@ void Interface::statH(Dose *comp) {
             maxFinal = statMax->getText().toDouble();
         }
 
-        int n = 0;
         for (int i = 0; i < data->size(); i++)
             if (doseList->selectedItems().contains(doseList->item(i))) {
                 temp.copyDose((*data)[i]);
@@ -2182,7 +2171,6 @@ void Interface::statH(Dose *comp) {
                                     + QString(" ") + "               |";
                     }
                 }
-                n++;
             }
 
         delete input;
@@ -2190,9 +2178,9 @@ void Interface::statH(Dose *comp) {
     delete file;
 
     if (statExtra->isChecked()) {
-        QString path2 = QFileDialog::getSaveFileName(0, tr("Save File"), 0,
+        QString path2 = QFileDialog::getSaveFileName(nullptr, tr("Save File"), QString(),
                         tr("Additional Statistics (*.txt)"));
-        if (path2 == 0) {
+        if (path2.isEmpty()) {
             return;
         }
 
@@ -2226,7 +2214,7 @@ void Interface::statHReg(Dose *comp) {
     yf = statyf->getText().toDouble();
     zf = statzf->getText().toDouble();
 
-    QString path = QFileDialog::getSaveFileName(0, tr("Save File "), 0,
+    QString path = QFileDialog::getSaveFileName(nullptr, tr("Save File "), QString(),
                    tr("Comma Separated Values ") +
                    tr("(*.csv)"));
     if (path == "") {
@@ -2375,7 +2363,6 @@ void Interface::statHReg(Dose *comp) {
                 }
             }
 
-        int n = 0;
         for (int i = 0; i < data->size(); i++)
             if (doseList->selectedItems().contains(doseList->item(i))) {
                 temp.copyDose((*data)[i]);
@@ -2456,7 +2443,6 @@ void Interface::statHReg(Dose *comp) {
                                     + QString(" ") + "               |";
                     }
                 }
-                n++;
             }
 
         delete input;
@@ -2464,9 +2450,9 @@ void Interface::statHReg(Dose *comp) {
     delete file;
 
     if (statExtra->isChecked()) {
-        QString path2 = QFileDialog::getSaveFileName(0, tr("Save File"), 0,
+        QString path2 = QFileDialog::getSaveFileName(nullptr, tr("Save File"), QString(),
                         tr("Additional Statistics (*.txt)"));
-        if (path2 == 0) {
+        if (path2.isEmpty()) {
             return;
         }
 
@@ -2508,7 +2494,7 @@ void Interface::statHMed(Dose *comp) {
             }
         }
 
-    QString path = QFileDialog::getSaveFileName(0, tr("Save File "), 0,
+    QString path = QFileDialog::getSaveFileName(nullptr, tr("Save File "), QString(),
                    tr("Comma Separated values ") +
                    tr("(*.csv)"));
     if (path == "") {
@@ -2657,7 +2643,6 @@ void Interface::statHMed(Dose *comp) {
                 }
             }
 
-        int n = 0;
         for (int i = 0; i < data->size(); i++)
             if (doseList->selectedItems().contains(doseList->item(i))) {
                 temp.copyDose((*data)[i]);
@@ -2739,7 +2724,6 @@ void Interface::statHMed(Dose *comp) {
                                     + QString(" ") + "               |";
                     }
                 }
-                n++;
             }
 
         delete input;
@@ -2747,9 +2731,9 @@ void Interface::statHMed(Dose *comp) {
     delete file;
 
     if (statExtra->isChecked()) {
-        QString path2 = QFileDialog::getSaveFileName(0, tr("Save File"), 0,
+        QString path2 = QFileDialog::getSaveFileName(nullptr, tr("Save File"), QString(),
                         tr("Additional Statistics (*.txt)"));
-        if (path2 == 0) {
+        if (path2.isEmpty()) {
             return;
         }
 
diff --git a/source/interface.h b/source/interface.h
index 76b5e01..f40a415 100644
--- a/source/interface.h
+++ b/source/interface.h
@@ -15,8 +15,6 @@
 #ifndef INTERFACE_H
 #define INTERFACE_H
 
-#define TRUE 1
-#define FALSE 0
 #include "egsphant.h"
 #include "dose.h"
 #include "previewer.h"
diff --git a/source/previewer.cpp b/source/previewer.cpp
index 2ac2887..e2ef89f 100644
--- a/source/previewer.cpp
+++ b/source/previewer.cpp
@@ -4,18 +4,21 @@
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Hover Label Class~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *******************************************************************************/
 void HoverLabel::mouseMoveEvent(QMouseEvent *event) {
-    if (event->x() > 0 && event->x() < width() && event->y() > 0 && event->y() < height()) {
-        emit mouseMoved(event->x(),event->y());
+    const QPointF pos = event->position();
+    if (pos.x() > 0 && pos.x() < width() && pos.y() > 0 && pos.y() < height()) {
+        emit mouseMoved(int(pos.x()), int(pos.y()));
     }
     event->accept();
 }
 
 void HoverLabel::wheelEvent(QWheelEvent *event) {
-    if (event->delta() > 0 && event->x() > 0 && event->x() < width() && event->y() > 0 && event->y() < height()) {
-        emit mouseWheelUp();
-    }
-    else if (event->x() > 0 && event->x() < width() && event->y() > 0 && event->y() < height()) {
-        emit mouseWheelDown();
+    const QPointF pos = event->position();
+    if (pos.x() > 0 && pos.x() < width() && pos.y() > 0 && pos.y() < height()) {
+        if (event->angleDelta().y() > 0) {
+            emit mouseWheelUp();
+        } else {
+            emit mouseWheelDown();
+        }
     }
     event->accept();
 }
@@ -111,7 +114,7 @@ void Previewer::createLayout() {
     //style += "}";
 
     errors = new QErrorMessage();
-    errors->setHidden(TRUE);
+    errors->setHidden(true);
     errors->setWindowTitle(tr("Error"));
     window = new QWidget();
     layout = new QGridLayout();
@@ -274,7 +277,7 @@ void Previewer::createLayout() {
 
     window->setStyleSheet(style);
     window->setLayout(layout);
-    window->setHidden(TRUE);
+    window->setHidden(true);
     window->setWindowTitle(tr("Previewer"));
 
     // Progress Bar
@@ -407,7 +410,7 @@ void Previewer::connectLayout() {
 *******************************************************************************/
 void Previewer::loadPhantom() {
     QString path =
-        QFileDialog::getOpenFileName(0, tr("Open File"), 0,
+        QFileDialog::getOpenFileName(nullptr, tr("Open File"), QString(),
                                      tr("EGSphant File (*.egsphant *begsphant)"));
     if (path == "") {
         return;
@@ -440,60 +443,47 @@ void Previewer::loadPhantom() {
 }
 
 void Previewer::checkBounds() {
-    char flag = FALSE;
     if (phant.nx && phant.ny && phant.nz) {
         if (!dimBox->currentText().compare("x axis")) {
             if (dimai->getText().toDouble() < phant.y[0]) {
                 dimai->setText(phant.y[0]);
-                flag++;
             }
             if (dimaf->getText().toDouble() > phant.y[phant.ny]) {
                 dimaf->setText(phant.y[phant.ny]);
-                flag++;
             }
             if (dimbi->getText().toDouble() < phant.z[0]) {
                 dimbi->setText(phant.z[0]);
-                flag++;
             }
             if (dimaf->getText().toDouble() > phant.z[phant.nz]) {
                 dimbf->setText(phant.z[phant.nz]);
-                flag++;
             }
         }
         else if (!dimBox->currentText().compare("y axis")) {
             if (dimai->getText().toDouble() < phant.x[0]) {
                 dimai->setText(phant.x[0]);
-                flag++;
             }
             if (dimaf->getText().toDouble() > phant.x[phant.nx]) {
                 dimaf->setText(phant.x[phant.nx]);
-                flag++;
             }
             if (dimbi->getText().toDouble() < phant.z[0]) {
                 dimbi->setText(phant.z[0]);
-                flag++;
             }
             if (dimaf->getText().toDouble() > phant.z[phant.nz]) {
                 dimbf->setText(phant.z[phant.nz]);
-                flag++;
             }
         }
         else if (!dimBox->currentText().compare("z axis")) {
             if (dimai->getText().toDouble() < phant.x[0]) {
                 dimai->setText(phant.x[0]);
-                flag++;
             }
             if (dimaf->getText().toDouble() > phant.x[phant.nx]) {
                 dimaf->setText(phant.x[phant.nx]);
-                flag++;
             }
             if (dimbi->getText().toDouble() < phant.y[0]) {
                 dimbi->setText(phant.y[0]);
-                flag++;
             }
             if (dimbf->getText().toDouble() > phant.y[phant.ny]) {
                 dimbf->setText(phant.y[phant.ny]);
-                flag++;
             }
         }
 		redraw();
@@ -876,7 +866,7 @@ void Previewer::updateImage() {
 		pen.setColor(Qt::black);
 		
 		QFont font;
-		font.setWeight(75);
+		font.setWeight(QFont::Bold);
 		font.setPointSize(16);
 		
 		painter.begin(picture);
@@ -920,7 +910,7 @@ void Previewer::updateImage() {
 }
 
 void Previewer::saveImage() {
-    QString path = QFileDialog::getSaveFileName(0, tr("Save File"), "",
+    QString path = QFileDialog::getSaveFileName(nullptr, tr("Save File"), QString(),
                    tr("PNG (*.png)"));
     if (path == "") {
         return;
@@ -946,8 +936,8 @@ void Previewer::updateDoses() {
 }
 
 void Previewer::closePreview() {
-    this->setDisabled(TRUE);
-    mom->setEnabled(TRUE);
+    this->setDisabled(true);
+    mom->setEnabled(true);
     window->hide();
 }
 
diff --git a/source/previewer.h b/source/previewer.h
index 2822a89..03cbaf2 100644
--- a/source/previewer.h
+++ b/source/previewer.h
@@ -1,8 +1,6 @@
 #ifndef PREVIEWER_H
 #define PREVIEWER_H
 
-#define TRUE 1
-#define FALSE 0
 #include "dose.h"
 #include "egsphant.h"
 
diff --git a/source/source.pro b/source/source.pro
index b077fb5..0beb584 100644
--- a/source/source.pro
+++ b/source/source.pro
@@ -1,23 +1,19 @@
 ######################################################################
-# Automatically generated by qmake (3.1) Thu Jun 25 15:03:50 2020
+# 3ddose_tools — Qt project file
 ######################################################################
 
 QT += widgets
+CONFIG += c++17 warn_on
 TEMPLATE = app
 TARGET = ../3ddose_tools
 INCLUDEPATH += .
 
-# The following define makes your compiler warn you if you use any
-# feature of Qt which has been marked as deprecated (the exact warnings
-# depend on your compiler). Please consult the documentation of the
-# deprecated API in order to know how to port your code away from it.
-DEFINES += QT_DEPRECATED_WARNINGS
+# Prefer a plain executable (matches historical Linux-oriented layout)
+macx: CONFIG -= app_bundle
 
-# You can also make your code fail to compile if you use deprecated APIs.
-# In order to do so, uncomment the following line.
-# You can also select to disable deprecated APIs only up to a certain version of Qt.
-#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0
+# Warn on (and disallow) APIs deprecated in or before Qt 6.0
+DEFINES += QT_DEPRECATED_WARNINGS
+DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000
 
-# Input
 HEADERS += dose.h egsphant.h interface.h previewer.h
 SOURCES += dose.cpp egsphant.cpp interface.cpp main.cpp previewer.cpp