Hybrid Imaging Shahid Younas M.Sc. Medical Physics (Surrey) UK M.Sc. Applied Physics (UET) Lahore Sr. Medical Physicist & RPA Picture courtesy of: Shahnawaz Shahid, Shazanan Shahid, Shazeen Shahid Department of Nuclear Medicine SKMCH&RC, LAHORE SPECT CT: HOW MUCH RADIATION DOSE Thanks to:
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Hybrid Imaging
Shahid YounasM.Sc. Medical Physics (Surrey) UK
M.Sc. Applied Physics (UET) Lahore
Sr. Medical Physicist & RPA
Picture courtesy of:
Shahnawaz Shahid,
Shazanan Shahid,
Shazeen Shahid
Department of Nuclear Medicine SKMCH&RC, LAHORE
SPECT CT: HOW MUCH RADIATION DOSE
Thanks to:
SPECT CT HYBRID
Material and Methodology
Reference 1: The Mnaual of SYMBIA SPECT/CT:SIEMENS, GERMANY.
We analyzed 151 patients from a dual-headed SIEMENS’ SYMBIA
T-16 unit with an integrated 16-slice CT scanner.
This CT portion of this system has,
variable tube current (20– 345 mA),
slice thickness of 0.6–10 mm,
rotational speed of 0.6–1.5 secs.
tube voltage up to 130 kVp.
Effective Dose
Reference 2: E. J. Hall and A. J. Giaccia, Radiolobiology for the Radiologist, Lippincott Williams &
Wilkins, Philadelphia, Pa, USA, 6th edition, 2005.
The quantity Effective Dose can have practical value for comparing
the relative doses related to the stochastic effects and comparing
different technologies [2]
Radiation Dose Conversation Mechanism
Reference 3: The Essential Physics of Medical Imaging, Third Edition Third, North American Edition Edition by Jerrold T. Bushberg (Author),
J. Anthony Seibert , Edwin M. Leidholdt Jr. , John M. Boone
Game of 10-10 sec [3]
Risk Factor
Reference 2: E. J. Hall and A. J. Giaccia, Radiolobiology for the Radiologist, Lippincott Williams &
Wilkins, Philadelphia, Pa, USA, 6th edition, 2005.
According to ICRP, the risk of developing a lethal cancer is
approximately 4% per Sievert. The lifetime risk for cancer has been
shown to be greater in the younger patients.
Dose Conversion
Reference 4: (AAPM, 2008), Report, Shope et al, 1981
CT dose index Volume (CTDIv) and Dose Length Product (DLP) are
two basic quantities used to estimate the average absorbed dose in
the organs and tissues based for the helical (volumetric) CT
scanners.[4]
Dose Length Product & CT Dose Indexvolume
CT Dose Calculations
Reference 5: International Commission on Radiological Protection (ICRP) Publication 53 and 80.
𝐷𝑜𝑠𝑒 𝐿𝑒𝑛𝑔𝑡ℎ 𝑃𝑟𝑜𝑑𝑢𝑐𝑡 = 𝐶𝑇𝐷𝐼𝑣 ∗ 𝑃𝑎𝑡𝑖𝑒𝑛𝑡 𝐿𝑒𝑛𝑔𝑡ℎ
𝐷𝐿𝑃 = 𝐶𝑇𝐷𝐼𝑣 ∗ 𝐿
DLP is measured in mGy*cm
CT Dose Calculations
Reference 5: International Commission on Radiological Protection (ICRP) Publication 53 and 80.