Treatment planning for radio-immunotherapy

Erdi, Alev K.; Erdi, Yusuf E.; Yorke, Ellen; Wessels, Barry W.

doi:10.1088/0031-9155/41/10/011

Cited by 43 publications

(21 citation statements)

References 83 publications

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“…Particularly, in radioimmunotherapy ͑RIT͒, data gathered from SPECT or PET images can provide important information related to the spatial distribution of radionuclides administered to patients in diagnosis and therapy. [1][2][3][4] Also, patient-specific anatomic information, obtained from CT and MRI images can be used for the construction of voxel-based geometric models of the human body, [5][6][7] where previously only models using approximate geometric constructs have been available. 8,9 The simulation of radiation transport by Monte Carlo techniques has become an important basic tool for dose calculations, and several program packages are currently available to treat problems in radiation protection and RIT dosimetry.…”

Section: Introductionmentioning

confidence: 99%

Absorbed fractions in a voxel‐based phantom calculated with the MCNP‐4B code

et al. 2000

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A new approach for calculating internal dose estimates was developed through the use of a more realistic computational model of the human body. The present technique shows the capability to build a patient-specific phantom with tomography data (a voxel-based phantom) for the simulation of radiation transport and energy deposition using Monte Carlo methods such as in the MCNP-4B code. MCNP-4B absorbed fractions for photons in the mathematical phantom of Snyder et al. agreed well with reference values. Results obtained through radiation transport simulation in the voxel-based phantom, in general, agreed well with reference values. Considerable discrepancies, however, were found in some cases due to two major causes: differences in the organ masses between the phantoms and the occurrence of organ overlap in the voxel-based phantom, which is not considered in the mathematical phantom.

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Section: Introductionmentioning

confidence: 99%

Absorbed fractions in a voxel‐based phantom calculated with the MCNP‐4B code

et al. 2000

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“…Clinical investigations in nuclear medicine demonstrates that minimum lesion detectability is about 1.5 cm in diameter (12,18,19,20). Assuming a spherical shape, this corresponds 1.77 ml of lesion volume.…”

Section: Discussionmentioning

confidence: 99%

Limits of Tumor Detectability in Nuclear Medicine and PET

Erdi¹

2012

Mirt

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Objective: Nuclear medicine is becoming increasingly important in the early detection of malignancy. The advantage of nuclear medicine over other imaging modalities is the high sensitivity of the gamma camera. Nuclear medicine counting equipment has the capability of detecting levels of radioactivity which exceed background levels by as little as 2.4 to 1. This translates to only a few hundred counts per minute on a regular gamma camera or as few as 3 counts per minute when using coincidence detection on a positron emission tomography (PET) camera. Material and Methods: We have experimentally measured the limits of detectability using a set of hollow spheres in a Jaszczak phantom at various tumor-to-background ratios. Imaging modalities for this work were (1) planar, (2) SPECT, (3) PET, and (4) planar camera with coincidence detection capability (MCD). Results: When there is no background (infinite contrast) activity present, the detectability of tumors is similar for PET and planar imaging. With the presence of the background activity , PET can detect objects in an order of magnitude smaller in size than that can be seen by conventional planar imaging especially in the typical clinical low (3:1) T/B ratios. The detection capability of the MCD camera lies between a conventional nuclear medicine (planar / SPECT) scans and the detection capability of a dedicated PET scanner.Conclusion: Among nuclear medicine’s armamentarium, PET is the closest modality to CT or MR imaging in terms of limits of detection. Modern clinical PET scanners have a resolution limit of 4 mm, corresponding to the detection of tumors with a volume of 0.2 ml (7 mm diameter) in 5:1 T/B ratio. It is also possible to obtain better resolution limits with dedicated brain and animal scanners. The future holds promise in development of new detector materials, improved camera design, and new reconstruction algorithms which will improve sensitivity, resolution, contrast, and thereby further diminish the limits of tumor detectability.Conflict of interest:None declared.

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“…Thus, suitable calculation models are required on this new scale. Generally speaking, the increasing awareness of the need to perform specific dosimetry for the patient in the context of a therapeutic application of radiopharmaceuticals has given rise to treatment planning systems for TR [159]. This represents a notable improvement compared to standard dosimetry performed on the basis of anthropomorphic phantoms.…”

Section: Dosimetry For Organs and Tissuesmentioning

confidence: 99%

Dosimetry and Microdosimetry of Targeted Radiotherapy

Bardiès

Pihet²

2000

CPD

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Dosimetry in targeted radiotherapy (TR) uses different calculation methods, whose degree of refinement is closely conditioned by the particular objective sought. It is more generally performed to establish a correlation between the quantity of radiation delivered to a target and the biological damage observed or that can be reliably predicted. It can thus be used to optimise treatments and allow comparison of different therapeutic approaches, as well as to study the basic methods of irradiation of biological matter. Two broad types of investigations can be found in the literature: microdosimetric ones (stochastic approaches used to study energy deposits) and macrodosimetric ones (non-stochastic or deterministic approaches). The mathematical formalism is consistent between these two types, and the calculation methods currently used are often similar. This review presents different approaches to the dosimetry of radionuclides used in TR. The introduction defines the general problem, the role of dosimetry in TR and the specific problems raised by targeting (non-uniformity of source distributions). The first part considers the types of calculation methods found in TR in relation to the basic quantities used to represent stochastic energy deposit on a cellular scale. In particular, it compares the formalism and the methods used in microdosimetric or conventional macrodosimetric approches. Although microdosimetry, or even track structure calculations, can provide the basic elements for modelling the absorbed dose process, a simplified dosimetric approach may be adequate to describe the phenomena observed. The scheme proposed by the MIRD committee relates to such an approach and is presented together with other methods allowing the calculation of the mean dose delivered (analytic methods, dose point kernels, Monte-Carlo, etc.). The second part shows the application range for the various methods, providing selected examples of dosimetric approaches in TR on different scales, from the organ (or tissues) to the cell or even DNA, and a brief presentation of bone marrow dosimetry.

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Treatment planning for radio-immunotherapy

Cited by 43 publications

References 83 publications

Absorbed fractions in a voxel‐based phantom calculated with the MCNP‐4B code

Absorbed fractions in a voxel‐based phantom calculated with the MCNP‐4B code

Limits of Tumor Detectability in Nuclear Medicine and PET

Dosimetry and Microdosimetry of Targeted Radiotherapy

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