I am working in a research and my hypothesis is ( The CT Dose Index (CTDIvol) was originally designed as an index not as a direct dosimetry method for patient dose assessment. There is no current method for calculating peak skin dose (PSD) using key metric provided from the radiation dose structure report of a CT scanner. Since every CT is required that each study has to output the dose, product and CT dose index volume, there is no direct method to go straight to the PSD. This project will test if the Size Specific Dose Estimate (SSDE) has a strong linear relationship with the peak skin dose. )
What I want is that others have contributed to your field historically, philosophically, or experimentally. What closely related problems, ideas, or solutions will you build on and use in your research? What contribution do you expect your research to make to the literature?
Here is the articles which are similar to mine and I want you to use:
https://academic.oup.com/rpd/article/157/4/536/1601922
https://pubmed.ncbi.nlm.nih.gov/33955655/
https://pubmed.ncbi.nlm.nih.gov/34311161/
that is what I am doing:
The CTDIvol displayed by the scanner will be validated to the true CTDIvol following the ACR testing guidelines. A correction factor will be used to correct any inaccuracies in the displayed value. This correction will also be applied to the DLP displayed by the scanner.
Peak skin dose and its relation will be measured by various phantoms such as NEMA phantoms, 16 cm CTDI and 32 cm CTDI phantoms. The phantoms will be aligned at the isocenter of the scanner with the chamber in the center hole of the phantom. The longitudinal axis of the chamber and cylindrical phantom will be aligned parallel to the longitudinal axis of the CT gantry. With using those different phantoms, the dosimeter will be placed serially in center hole ad peripheral hole. Those measurements are combined to produce the weighted CTDI, so a 100-mm-long cylindrical (pencil) chamber, approximately 9 mm in diameter, inserted into either the center or a peripheral hole of a phantom as shown in figure 1, and with the pencil chamber located at the center (in the z-dimension) of the phantom and also at the center of the CT gantry, a single axial CT scan is made. An ionization chamber can only produce an accurate dose estimate if its entire sensitive volume is irradiated by the x-ray beam. Therefore, for the partially irradiated 100-mm CT pencil chamber, the nominal beam width which is the total collimated x-ray beam width as indicated on the CT console, is used to correct the chamber reading for the partial volume exposure. The 100-mm chamber length is useful for x-ray beams of thin slices such as 5 mm to thicker beam collimations such as 40 mm. The correction for partial volume is essential and is calculated using the correction for partial volume is essential and is calculated using which B can be either the total collimated beam width, in mm, for a single axial scan or the width of an individual CT detector (T)
number of active detectors (n)
Then the CTDI will be calculated as CTDI100 = (1/3) x CTDIcenter + (2/3) x CTDIperiphery. Combining the center and peripheral measurements using a 1/3 and 2/3 weighting scheme provides a good estimate of the average dose to the phantom at the central CT slice along z, giving rise to the weighted CTDI, CTDIw. The CTDI100, which is the amount of radiation delivered to one slice of the body over a long CT scan and it is also known as CTDI weighted. The scanner scans the entire volume in a helical trajectory. Thus, there isn’t really a true ‘slice’, as the z-position of the scanner is different at each angle. Also, the spacing between successive revolutions of the CT tube represents the pitch of the scan. In fact, the wider the helix, the less dose the patient will receive because the same portion of tissue is being irradiated at fewer angles, so the larger the pitch the lower the dose. Therefore, CTDIvol represent the dose for a specific scan protocol which considers gaps and overlaps between the radiation dose profile from consecutive rotations of the x-ray source and it can be calculated; CTDIvol = (1/pitch) x CTDIw. The CTDIw represents the average radiation dose over the x and y direction whereas CTDIvol represents the average radiation dose over the x, y and z directions.
Nanodot dosimeters will be placed on the LAT and AP locations as shown in figure 2, the dose to the skin will be measured at these locations. Then, the phantoms will be scanned over the scan length for a fixed value of the tube current. The measurement will be repeated several times using various scanning techniques (with varying energy, current). Size conversion factors used will be based on the dimension of the phantom being scanned used. These K-factors with the CTDIvol can produce size specific dose estimates (SSDEs), and since the CT dose index will be provided at the CT scanner too, the size specific dose estimate for the phantoms will be calculated. Also testing if the correlation between the size specific dose estimate and the measurement of the peak skin dose match will be done, and if such a relationship exists, trying to find that factor will be the aim.
