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Sci—Thurs AM: YIS—05: Accuracy of Patient‐Specific Dosimetry for Clinical Use in Targeted Radionuclide Therapy
Author(s) -
Grimes J,
Shcherbinin S,
Celler A,
Birkenfeld B,
Listewnik MH,
Zorga P,
PiwowarskaBilska H
Publication year - 2009
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3244165
Subject(s) - dosimetry , nuclear medicine , radionuclide therapy , effective dose (radiation) , monte carlo method , biodistribution , medicine , medical physics , internal dosimetry , radiation treatment planning , radionuclide , radiation therapy , physics , mathematics , radiology , chemistry , statistics , nuclear physics , biochemistry , in vitro
Targeted radionuclide therapy (TRT) uses radiopharmaceuticals that target tumour tissue, potentially delivering large radiation doses to tumours, while minimizing the dose to surrounding healthy tissue. In this work we investigated how various approximations affect the accuracy of patient‐specific dose calculations in TRT. Methods: Time‐activity curves (TACs) were acquired from a series of nuclear medicine images, including one SPECT/CT image and multiple planar scans in two patients. Biodistribution of radiopharmaceutical was modeled using: an exponential fit, trapezoidal areas, and without the use of a long term scan to draw the TACs. Cumulated activities (area under TACs) were determined and used in three different dose calculation methods: OLINDA/EXM code, MIRD voxelized S‐values (MVSV), and Monte Carlo simulation (MCS), considered here as the gold standard. Results: Different methods for drawing TACs showed that resulting areas under the curve differ by up to a factor of 4. For dose calculation, OLINDA and MVSV doses differed from the average MCS dose by 5% and 3% respectively. OLINDA does not provide details of dose distribution throughout the tumour, whereas MVSV does. The drawback of MVSV is that it assumes a source material of uniform density. Conclusions: An accurate determination of the TAC is essential for proper dosimetry. Both the OLINDA code and MVSV provide average tumour doses that match the MCS results. MVSV is more versatile than OLINDA and can be used to calculate dose distributions that closely resemble the MCS dose for tumours located in regions with reasonably uniform tissue density.