Evaluation of Changes in Dose Estimation on Abdomen CT Scan with Automatic Tube Current Modulation Using In-House Phantom

This study evaluates the effect of the Automatic Tube Current Modulation (ATCM) technique on pitch and effective diameter variation in estimating dose values and noise levels for abdominal examination on Philips Ingenuity CT scan machine using in-house Phantoms. The in-house phantoms are oval in shape with three effective diameter sizes, namely 23.2 cm, 28.3 cm, and 33.3 cm to represent abdominal region. The three size Phantoms were scanned using an Ingenuity 128 Philips CT scan with the abdominal protocol exposure parameters of 120 kVp tube voltage, Dose Right Index (DRI) variations of 10,11,12,13, and 14, and pitch variations of 0.6; 0.8; 1.0; 1.2; and 1.49. The changes in mAs, CTDIvol, and noise to the Philips reference value were then verified (i.e. an addition of one DRI value increases mAs by 12 %). For evaluation, a metric to express the change in DRI is defined as ΔDRI. The study demonstrates that noise level is influenced by object size; size information of the object could be useful to predict the change of tube current and pitch due to ATCM with respect to selected DRI. The DRI value is proportional to the tube current, thus selecting the DRI at a certain pitch will directly determine tube current. The ΔDRI in general, according to Philips specifications, is verified to be approximately 10 % to 13 %, except for DRI 10 to 11 which is relatively high on average 15 % to 17 %. Increasing DRI increases the CTDIvol. The CTDI/mAs constantly ranges of 0.06 to 0.07. The value could serve as a characteristic parameter for quality assurance. The ATCM specifications of the Ingenuity 128 CT Scanner is according to Philips regulations

Pemanfaatan Limbah Cangkang Telur Ayam Dan Bebek Sebagai Sumber Kalsium Untuk Sintesis Mineral Tulang

Penelitian ini bertujuan untuk membuat biomaterial substitusi tulang yang menyerupai komposisi tulang sebenarnya, yang terdiri dari mineral inorganik (apatit) dan bahan organik sebagai matriks. Pada penelitian ini metode presipitasi digunakan dalam pembuatan komposit apatit-kitosan dengan menggunakan cangkang telur ayam dan bebek sebagai sumber kalsium dan KH2PO4 sintetik sebagai sumber posfat. Cangkang telur dan KH2PO4 sebagai mineral inorganik tulang, sedangkan matriks organik yang digunakan adalah kitosan dari kulit udang. Cangkang telur ayam dan bebek dikalsinasi untuk menghilangkan semua komponen karbonat (CO3) sehingga didapatkan CaO sebagai sumber kalsium. Komposit apatit-kitosan dibuat dengan menumbuhkan senyawa kalsium posfat pada matriks dengan metode ek situ. Sampel yang dihasilkan selanjutnya dikeringkan pada suhu 50 oC. Karakteristik sampel selanjutnya dianalisis menggunakan X-ray Diffraction (XRD) dan Fourier Transform Infrared (FTIR) Spectroscopy. Pola XRD sampel memperlihatkan adanya puncak-puncak difraksi untuk kristal apatit. Data tersebut didukung oleh spektrum FTIR yang memperlihatkan puncak transmitansi dari fosfat dan karbonat dari kristal apatit. This study aimed to develop bone substituted biomaterial consisting of inorganic mineral (apatit) and organic material as matrix. In this study, a precipitation method of apatite-chitosan composite synthesis has been used using hen\u27s and duck\u27s eggshell as calcium source and synthetic KH2PO4 as phosphate source. The eggshell and KH2PO4 act as inorganic mineral, whereas organic matrix used was chitosan originated from shrimp shell. The eggshell was calcinated to decompose all the carbonate (CO3) phases. To produce the composite, calcium phosphates were grown on organic matrix of chitosan using ex situ method. The result samples were further dried at 50 oC. Characteristic of the samples were performed using X-ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) Spectroscopy. The XRD profile illustrated specific diffraction angles at peaks of apatite crystals. This data were supported by FTIR spectra that showed transmittance peak of phosphates and carbonates from apatites

Noise Suppression of Computed Tomography (CT) Images Using Residual Encoder-Decoder Convolutional Neural Network (RED-CNN)

In this study, an in-house residual encoder-decoder convolutional neural network (RED-CNN)-based algorithm was composed and trained using images of cylindrical polymethyl-methacrylate (PMMA) phantom with a diameter of 26 cm at different simulated noise levels. The model was tested on 21 × 26 cm elliptical PMMA computed tomography (CT) phantom images with simulated noise to evaluate its denoising capability using signal to noise ratio (SNR), comparative peak signal-to-noise ratio (cPSNR), structural similarity (SSIM) index, modulation transfer function frequencies (MTF 10 %) and noise power spectra (NPS) values as parameters. Evaluation of a possible decrease of image quality was also performed by testing the model using homogenous water phantom and wire phantom images acquired using different mAs values. Results show that the model was able to consistently increase SNR, cPSNR, SSIM values, and decrease the integral noise power spectra (NPS). However, the noise level on either training or testing data affects the model’s final denoising performance. The lower noise level on testing data images tends to result in over-smoothed images, as indicated by the shift of the NPS curves. In contrast, higher simulated noise level tends to result in less satisfactory denoising performance, as indicated by lower SNR, cPSNR, and SSIM values. Meanwhile, the higher noise level on training data images tends to produce denoised images with reduced sharpness, as indicated by the decrease of the MTF 10 % values. Further studies are required to better understand the character of RED-CNN for CT noise suppression regarding the optimum parameters for best results

Construction and Evaluation of a Multipurpose Performance Check Phantom for Computed Tomography

The use of computed tomography (CT) has become a common practice in medical diagnosis in Indonesia. Its number, however, is not matched by the availability of dedicated-performance-check phantoms. This paper aims to describe the design, construction, and evaluation of an in-house phantom for CT performance check that accommodates both radiation dose measurement and image quality performance checks. The phantom is designed as laser-cut polymethyl methacrylate (PMMA) slabs glued together to form a standard cylindrical shape, with spaces to place dose measurement and image quality modules. In this paper, measurement results on both aspects are discussed and compared with standard phantoms and other works. For dose measurement, the constructed phantom exhibited the greatest absolute discrepancy against the reference standard phantom of 8.89 %. Measurement of the CT number linearity and modulation transfer function (MTF) yielded, at most, 7.51 % and 5.07 % discrepancies against Catphan 604, respectively. Meanwhile, although found to be more linear in the phantom-based contrast linearity test, the use of the in-house phantom for clinical image contrast threshold determination requires further study. For noise power spectrum (NPS) measurement, accurate results were obtained within a limited range of spatial frequency

KARAKTERISASIGUGUSFOSFATDANKARBONATDALAMTULANGTIKUSDENGAN FOURIER TRANSFORM INFRARED (FT-IR) SPECTROSCOPY

KARAKTERISASIGUGUSFOSFATDANKARBONATDALAMTULANGTIKUSDENGAN FOURIER TRANSFORM INFRARED (FT-IR) SPECTROSCOPY. Telah dilakukan penelitian untuk mengetahui karakteristik kalsium fosfat dalam tulang tikus menggunakan spektroskopi FT-IR. Sampel tulang femur dan tibia diperoleh dari tikus jenis Sprague-Dawley. Variasi umur yang diambil yaitu 1bulan hingga 8 bulan. Untuk menghilangkan komponen organik, sampel diberi perlakuan menggunakan hidrazin. Maksimal pita absorpsi 3 fosfat spektrum FT-IR tulang tikus berada disekitar 1036 cm-1.Pita absorpsi 4 fosfat dalam mineral tulang tikus terpecah dengan puncak sekitar 566 cm-1 dan 599 cm-1. Keberadaan pita absorpsi 1, 3, dan 4 karbonat menunjukkan kalsium fosfat mineral tulang hadir dalam bentuk apatit karbonat. Peningkatan umur mengakibatkan penurunan kandungan fosfat dan karbonat dalam mineral tulang tikus

Medical physics aspects of cancer care in the Asia Pacific region

Medical physics plays an essential role in modern medicine. This is particularly evident in cancer care where medical physicists are involved in radiotherapy treatment planning and quality assurance as well as in imaging and radiation protection. Due to the large variety of tasks and interests, medical physics is often subdivided into specialties such as radiology, nuclear medicine and radiation oncology medical physics. However, even within their specialty, the role of radiation oncology medical physicists (ROMPs) is diverse and varies between different societies. Therefore, a questionnaire was sent to leading medical physicists in most countries/areas in the Asia/Pacific region to determine the education, role and status of medical physicists