RMDP: A Dedicated Package For ¹³¹I SPECT Quantification, Registration and Patient-Specific Dosimetry

Abstract

The limitations of traditional targeted radionuclide therapy (TRT) dosimetry can be overcome by using voxel-based techniques. All dosimetry techniques are reliant on a sequence of quantitative emission and transmission data. The use of (131)I, for example, with NaI or mIBG, presents additional quantification challenges beyond those encountered in low-energy NM diagnostic imaging, including dead-time correction and additional photon scatter and penetration in the camera head. The Royal Marsden Dosimetry Package (RMDP) offers a complete package for the accurate processing and analysis of raw emission and transmission patient data. Quantitative SPECT reconstruction is possible using either FBP or OS-EM algorithms. Manual, marker- or voxel-based registration can be used to register images from different modalities and the sequence of SPECT studies required for 3-D dosimetry calculations. The 3-D patient-specific dosimetry routines, using either a beta-kernel or voxel S-factor, are included. Phase-fitting each voxel's activity series enables more robust maps to be generated in the presence of imaging noise, such as is encountered during late, low-count scans or when there is significant redistribution within the VOI between scans. Error analysis can be applied to each generated dose-map. Patients receiving (131)I-mIBG, (131)I-NaI, and (186)Re-HEDP therapies have been analyzed using RMDP. A Monte-Carlo package, developed specifically to address the problems of (131)I quantification by including full photon interactions in a hexagonal-hole collimator and the gamma camera crystal, has been included in the dosimetry package. It is hoped that the addition of this code will lead to improved (131)I image quantification and will contribute towards more accurate 3-D dosimetry.

Recommendations of the American Association of Physicists in Medicine on dosimetry, imaging, and quality assurance procedures for 90Y microsphere brachytherapy in the treatment of hepatic malignancies

“…Several efforts to use image data to perform high quality detailed dose calculations include the 3D-ID code from the Memorial Sloan-Kettering Cancer Center, 31 the SIMDOS code from the University of Lund, 32 the RTDS code from the City of Hope Medical Center, 33 the RMDP code from Royal Marsden, 34 and the DOSE3D code. 35 The PERE-GRINE Monte Carlo code 36 has also been proposed for three-dimensional, computational dosimetry, and treatment planning in radioimmunotherapy.…”

Impact of SPECT corrections on 3D‐dosimetry for liver transarterial radioembolization using the patient relative calibration methodology

“…16 An optimal treatment planning should include 3D voxelbased dosimetry, accounting for nonuniform absorbed dose distributions when studying dose-effect correlations. 9,[17][18][19][20][21][22][23] Image-based 3D dosimetry can be performed in several ways: direct Monte Carlo (MC) simulation, which is considered the gold standard; 9,[24][25][26][27][28][29][30] convolution calculations by voxel S-values, reliable in nearly uniform density tissue; 19,[31][32][33][34][35][36] local energy deposition method. 18,20,[36][37][38][39] Activity distribution quantification by SPECT is the major concern, due to physical and clinical degrading factors of the images.…”

MIRD Pamphlet No. 25: MIRDcell V2.0 Software Tool for Dosimetric Analysis of Biologic Response of Multicellular Populations

“…However, there have been dramatic improvements in dosimetry models that reflect the substructure of organs as well as tissue elements within them (3)(4)(5). These models rely on improved nuclear medicine imaging capabilities that facilitate determination of activity within the voxels that represent tissue elements that are about 0.2-1 cm 3 in volume (6)(7)(8)(9). However, even these improved approaches assume that all cells within the tissue element receive essentially the same absorbed dose.…”