TY - JOUR T1 - Detection of <sup>90</sup>Y Extravasation by Bremsstrahlung Imaging for Patients Undergoing <sup>90</sup>Y-Ibritumomab Tiuxetan Therapy JF - Journal of Nuclear Medicine Technology JO - J. Nucl. Med. Technol. SP - 195 LP - 198 DO - 10.2967/jnmt.110.077354 VL - 38 IS - 4 AU - Stephanie M. Rhymer AU - J. Anthony Parker AU - Matthew R. Palmer Y1 - 2010/12/01 UR - http://tech.snmjournals.org/content/38/4/195.abstract N2 - Extravasation of therapeutic 90Y-ibritumomab tiuxetan can cause significant injury. Detection of extravasated 90Y using a γ-camera for patients undergoing 90Y-ibritumomab tiuxetan therapy is a challenge because of the inherently low efficiency of bremsstrahlung imaging and the interference of prompt and scattered photons from 111In that are still present in the body at the time of 90Y injection. We have configured a γ-camera to image bremsstrahlung radiation from superficial 90Y in the presence of 111In and evaluated the effectiveness using phantoms. Methods: Phantoms were constructed to contain 90Y and 111In with activity levels and with a geometry approximating conditions in a patient being scanned for evaluation of possible extravasation in the antecubital fossa. Imaging was performed using a camera equipped with medium-energy general-purpose (MEGP) and high-energy general-purpose (HEGP) collimators. Results: The contrast that developed between the patch representing extravasated solution and the background was comparable for MEGP and HEGP collimators. With MEGP collimators and 5-min acquisitions, a patch containing 8.3 MBq (220 μCi) distributed over an elliptic area of 7 × 11 cm was clearly discernable. Conclusion: With our experimental arrangement, the lower limit of detection is approximately 8 MBq. We calculate that an extravasation of this much 90Y would result in an absorbed dose to the skin and subcutaneous tissue of 2.5 Gy, which is close to the threshold for skin damage. This technique is therefore sensitive enough to be of use in the clinic when extravasation of 90Y is suspected. ER -