This study focused on several aspects of CTPA (Computed Tomography Pulmonary Angiogram) imaging. Primarily to reinforce and substantiate previous research done in the fields of low voltage CTPA acquisition by analysing data obtained during study and seeing what the resultant reduction in kV (Kilovoltage) has on attenuation levels in the pulmonary vessels and whether the decrease in signal intensity adversely affects image quality to any significant degree. To compare bolus tracking and test bolus in CTPA imaging.150 patients were involved and imaged between January 2015 and August 2015. 50 pts were scanned at 100kVp with Test Bolus (Group A). 50 pts were scanned at 120kVp using Bolus Tracking (Group B). 50 patients were scanned at 120kVp using Test Bolus (Control Group). Vascular enhancement, Signal to Noise Ratio (SNR), Contrast to Noise Ratio (CNR), image noise, radiation dosimetry, and contrast use were recorded. Subjective image quality was assessed by two blinded radiologists. All injections took place at a rate of 4ml/sec through an 18 gauge bore cannula sited at the antecubital fossa. Flow rate was kept constant at 4ml/sec throughout the procedure. At both 100 and 120kVp, the injected iodine concentration was the same.The reduction in tube potential resulted in an increase in mean attenuation measured in Hounsfield Units (HU) in the main pulmonary of 25.1% (307.46 to 410.48). Despite a 30% increase in image noise at 100kV there was no significant impact on SNR or CNR values. Radiation dose was considerably decreased by 40% at 100kV with no noteworthy difference in image quality in the images assessed. Use of Test Bolus decreased contrast use by over 25% from the standard amount of 80mls but which had no effect on the attenuation values.