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With the introduction of the Computed Tomography (CT) into the SPECT technology, SPECT-CT is now capable to quantify the uptake to the organ by the introduction of Activity Calibration Factor (ACF). We implemented three different phantoms geometry to obtain the ACF. First acquisition done with uniform cylinder phantom from Data Spectrum, followed with uniform NEMA IEC Body and uniform glass bottle allows the simulation of different type of clinical imaging study. Acquisitions were performed on a Brightview XCT (Philip) gamma camera. All acquisition and reconstruction protocol according to the clinical practice setting with different voxel volume sizes of 0.811 cm3, 0.104 cm3 and 0.012 cm3 to demonstrate the different values of ACFs. The ACFs for Tc-99m, I-131 and Lu-177 calculated from 3D segmentation of SPECT-CT images for scaling three different matrix sizes. The results obtained in this study demonstrated that SPECT-CT is able to quantify uptake at the organ, and it has high possibility to be used as quantitative SPECT in clinical practice in the future.

Tumour volume measurement requires physicist to perform manual delineation for every slice of 2D image produced by SPECT-CT to obtain the total number of pixel of abnormal activities. The total number of pixel is multiplied with spatial resolution of each pixel and thickness between each slice. Physicist delineate abnormal activities of tumour subjectively which lead to inconsistent accuracy of the measured volume. Manual delineation process requires high consumption of time and effort. This work is aimed to verify and validate an in-house developed algorithm that capable of numerically quantify the tumour volume. The results were compared with the actual and manually calculated volume of Phantom Body, scanned with SPECT-CT apparatus. The algorithm verification is performed by comparing the algorithm structure and preliminary results with previous works. The data for validation were obtained by conducting experiment with NEMA-IEC body phantom and Iodine-131. The algorithm structure and outcome were comparable with previous works with slight modification. The algorithm measured volume is 26.9579 cm3 which is only 1.6% error as compared to the actual tumour volume of 26.521 cm3. The algorithm is expected to be used for actual patient data in the near future once sufficient verification and validation procedures are achieved.

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