CTPA Protocol: Enhancing Skills in CT Protocols Development

Protocol critique

TABLE OF CONTENTS
AIM..................................................................................................................................................1
INTRODUCTION...........................................................................................................................1
PROTOCOL ...................................................................................................................................1
Contradictions and indications ....................................................................................................1
Contrast needs and room preparation .........................................................................................2
Considerations, adaptations and patient preparation ..................................................................2
Exposure risks and dose reduction ..............................................................................................3
Tube rotation time, beam collimation and pitch .........................................................................3
Windowing and reconstruction algorithm ..................................................................................3
Interval and reconstruction slice thickness .................................................................................4
Patient alignment and position ....................................................................................................4
Contrast timing and volumes ......................................................................................................4
Anatomy and scanning range ......................................................................................................5
Post processing requirements.......................................................................................................5
CONCLUSION ...............................................................................................................................5
REFERENCES ...............................................................................................................................6

AIM
To enhance the skills used in CT protocols development in clinical setting.
INTRODUCTION
Computed tomography is also known as CT scan and is an image test which is used for
the diagnosis of images of blood vessels, soft issues, internal organs and bones. CT provides
images in multiple planes and three dimensional images which can be analysed and shared. For
the precise diagnosis and analysis of CT it is essential for the clinicians to obey and consider
scanning instructions or the protocols (Vanier and Caplan, 2017). CT protocol describes the rules
and techniques as a reference for technologists and radiology residents. The report will discuss
the necessity and various elements of CT protocols such as its rotation time, adaptations,
scanning range and reconstruction algorithm.
PROTOCOL
CT pulmonary angiogram (CTPA) protocol explain the diagnosis principles of CT
angiography. It provides the image of pulmonary arteries for the diagnosing pulmonary
embolism (PE). It requires only intravenous line for the scanning purpose and thus is invasive in
nature. CTPA protocols assures that intravenous injection of contrast agent containing iodine is
provided to patient at high rate. As a result, images are obtained with the optimum radio opaque
contrast. In order to give the picture of blood vessels contrast dye is injected into blood vessels in
arm or groin. During the test x-ray or fluoroscopy is used to scan the dye and to generate the
image (Dekkers and et.al., 2016). When multi-detector CT scanner used for CTPA then best
results are obtained. However, it has been observed that individuals which have higher risk of
nephropahty dual energy CT can be used to lower the contrast amount. With the implications of
this protocol bolus tracking is used in the clinics or hospitals. Bolus tracking helps to commence
the scanning only when the level of contrast matches the level of pulmonary proximal.
Contradictions and indications in the scanning of blood clots in lungs
CTPA is widely used for the scanning of artery blockage in the lungs and thus for this
report lungs are scanned. CTPA scan demonstrates the mass filling defects like fat or embolus in
pulmonary vessels in the form of dark appearances. Thus, this protocol helps to diagnose the
blood clots in lungs which travels from pelvis or leg veins to cause a blockage in the flow of
blood. It is strictly ensured that scanning process must be accomplished before contrast reaches
to aorta or the left side of the heart. This protocol element is necessary as it indicates that there is
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need of large contrast media dose. One of the contradiction associated with this protocol is its
usage during pregnancy (Gillespie and et.al., 2019). The ionizing radiations used in CTPA makes
it less suitable during pregnancy. During pregnancy the sensitivity of breasts increases and thus
can have adverse impact on thyroid gland of fetus.
(Source: CT angiography of the abdominal wall to study the inferior epigastric system for DIEP
flap breast reconstruction, 2011)
Contrast needs and room preparation
CTPA is carried out in radiology scanning room. The room consist of scanning table on
which patient can lay flat and head is positioned in docking pillow. The CT scanner donut is
movable and pass around patients so that scan can be completed. For creating the scan, a gantry
is also provided in the room which can travel from neck to abdomen. For the scanning and
diagnosis purpose intravenous contrast is selected. This contrast highlights and demonstrates the
pulmonary vessels
Considerations, adaptations and patient preparation
For the accurate results of CTPA timing is very critical parameter. Thus clear and
suitable instructions must be given by the radiographers to patient for holding breath as well as to
breath in and breath out. Since the test has contradictions and risks related to pregnancy it is
required that patients must informed regarding this prior to the test. From the safety purpose the
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Illustration 1: CTPA interpretation