title: The radiation dose to overweighted patients undergoing myocardial perfusion SPECT can be significantly reduced: validation of a linear weight-adjusted activity administration protocol.
abstract: Large body size can cause a higher proportion of emitted photons being attenuated within the patient. Therefore, clinical myocardial perfusion SPECT (MPS) protocols often include unproportionally higher radioisotope activity to obese patients. The aim was to evaluate if a linear weight-adjusted low-dose protocol can be applied to obese patients and thereby decrease radiation exposure.
  
  
  
  Two hundred patients (>110 kg, BMI 18-41, [n = 69], ≤ 110 kg, BMI 31-58, [n = 131]) underwent99mTc-tetrofosmin stress examination on a Cadmium Zinc Telluride or a conventional gamma camera using new generations of reconstruction algorithm (Resolution Recovery). Patients <110 kg were administered 2.5 MBq/kg, patients between 110 and 120 kg received 430 MBq and patients >120 kg received 570 MBq according to clinical routine. Patients >110 kg had 130% total number of counts in the images compared to patients <110 kg. Recalculating the counts to correspond to an administered activity of 2.5 MBq/kg resulted in similar number of counts across the groups. Image analyses in a subgroup with images corresponding to high activity and 2.5 MBq/kg showed no difference in image quality or ischemia quantification.
  
  
  
  Linear low-dose weight-adjusted protocol of 2.5 MBq/kg in MPS can be applied over a large weight span without loss of counts or image quality, resulting in a significant reduction in radiation exposure to obese patients.
authors: Department of Radiation Physics, Skåne University Hospital and Lund University, Lund, Sweden.
authors: Jenny
authors: J
authors: Oddstig
authors: Department of Radiation Physics, Skåne University Hospital and Lund University, Lund, Sweden.
authors: Cecilia
authors: C
authors: Hindorf
authors: Department of Clinical Physiology and Nuclear Medicine, Skåne University Hospital and Lund University, 221 85, Lund, Sweden.
authors: Fredrik
authors: F
authors: Hedeer
authors: Department of Clinical Physiology and Nuclear Medicine, Skåne University Hospital and Lund University, 221 85, Lund, Sweden.
authors: Jonas
authors: J
authors: Jögi
authors: Department of Clinical Physiology and Nuclear Medicine, Skåne University Hospital and Lund University, 221 85, Lund, Sweden.
authors: Håkan
authors: H
authors: Arheden
authors: Department of Clinical Physiology and Nuclear Medicine, Skåne University Hospital and Lund University, 221 85, Lund, Sweden.
authors: Magnus J
authors: MJ
authors: Hansson
authors: Department of Clinical Physiology and Nuclear Medicine, Skåne University Hospital and Lund University, 221 85, Lund, Sweden. henrik.engblom@med.lu.se.
authors: Henrik
authors: H
authors: Engblom
mesh_terms: D000368:Aged; D001835:Body Weight; D002985:Clinical Protocols; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging; D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D050177:Overweight / Q000000981:diagnostic imaging*; D011829:Radiation Dosage; D000069079:Radiation Exposure; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; C078700:technetium tc-99m tetrofosmin
keywords: CZT detector; Myocardial perfusion imaging: SPECT; conventional gamma camera; image quality; radiation dose