HRCT (High-Resolution Computed Tomography) Chest - Plain refers to a CT scan that gives a more precise cross-section image of the lungs than a regular chest CT. HRCT scan of the chest is an imaging procedure that uses narrow beams of X-rays to create a high-resolution image of the lung anatomy. This test is done to assess the function of the lungs, to detect abnormal growth in the lungs, and to detect obstruction to airflows through the lungs.