PLANET® Dose: The Complete Dosimetry Software for SIRT

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The use of Selective Internal Radiation Therapy (SIRT) for patients with unresectable liver cancers is growing around the world. Today, activity planning for SIRT is based on simple methods that are easy to apply clinically, but are not always including dose computation. Several studies emphasize on the dose-effect relationship for SIRT. Indeed, if a tumor receives a dose lower than expected, there is a risk of stability or progression and if the non tumoral tissue receives a dose higher than the tolerated one, there is a risk of toxicity. As a result, there is a high interest for precise calculations and dose analysis tools, such as the ones used in External Beam Radiation Therapy (EBRT).

PLANET® Dose offers a complete, versatile, high performance and vendor-neutral solution targeted to help the medical team in the management of SIRT and to allow advanced dosimetry analysis.

How does PLANET® Dose work? It is a very simple process:

  • First, contouring of the volumes of interest can be performed/imported on PLANET® Dose using the diagnostic anatomical and/or functional imaging.
  • As a simulation step, 99Tcm-MacroAggregated of Albumin (MAA) are injected in the hepatic artery. The 99Tcm-MAA-SPECT/CT images acquired after administration, can be imported and analyzed in PLANET® Dose for different purposes. The lung shunt fraction can be easily evaluated to prevent any lung overexposure to radiation. A predictive MAA-based 3D dosimetry at the voxel level can be performed to get an accurate and personalized treatment planning. Similar tools as the ones commonly used in EBRT are available to analyze dose distribution to target volumes and Organs At Risk (OAR). In addition to isodose display, Dose Volume Histogram (DVH) enables to know what amount of dose was received by a percentage of a Volume Of Interest (VOI). Plus the mean dose to the volume, DVHs provide information regarding dose distribution homogeneity.
  • The patient is then injected with the 90Y-microspheres (MS) and the post-treatment 90Y-MS-PET/CT images are sent to PLANET® Dose. Following the same process as with the MAA, the treatment’s delivery is analyzed on the 90Y-MS-PET/CT, to verify the real dose given to the tumor(s) and OAR. A dosimetry comparison can be completed between 99Tcm-MAA treatment planning and 90Y-MS in vivo control.
  • PLANET® Dose is an end-to-end solution since it can also be used for assessing therapy response (RECIST 1.1 and PERCIST 1.0 criteria).
  • The nuclear medicine physician can then export all the results (VOI, dose map, HDV, etc.) including formatted report to the patient’s record for follow-up and consolidation.

PLANET® Dose is specialized to optimize the dosimetry step of SIRT in order to personalize the treatment for each patient.

Here are some examples of case studies:

  • Patient with portal vein thrombosis: target volume dose optimization.

Portal vein thrombosis targeting is essential for patient care. In that case, dose values can be assessed in any compartment with the help of PLANET® Dose. Therefore, the portal vein thrombosis can be part of dose optimization between target and non target volumes and consequently, the amount of activity to be administered is adapted;

  • Patient with a whole liver treatment: sparing the gallbladder.

During MAA-based predictive dosimetry, the gallbladder delineated on the diagnostic MRI is included in the OAR to spare. A dose limit is set and activity-to-administer is planned complying with dose constraints to each volume as much as possible. In this way, a personalized treatment is conducted on the patient. Doses delivered to each compartment can be calculated in vivo based on the 90Y-MS- PET/CT images helping the medical team in the patient therapy follow-up;

  • Patient case that requires multiple treatments: an overall dose estimation.

With PLANET® Dose, 3D voxelized dosimetry can be used to calculate the total dose delivered to the liver throughout all the treatments. It allows the medical team the possibility to sum up the doses to the tumoral and non-tumoral liver given at each treatment and better plan for future 90Y-MS injections or other therapies.

15 hospital centers are currently using PLANET® Dose as their software of choice, providing dosimetry and an integration of oncology features with versatile and high features for the whole clinical workflow. The renowned Netherlands Cancer Institute in Amsterdam has selected PLANET® Dose as their solution to match their short terms needs and future requirements to support new radionuclide based therapies.

Indeed, PLANET® Dose can support the whole process of systemic therapies (multi-time points elastic registration, automatic deformable propagation of VOI across times, residence time calculation, etc.) and provides an advanced dosimetry solution for 177Lu-based treatment.

Learn about DOSIsoft current and upcoming software solutions at www.dosisoft.com

Authors of this article: 

Sébastien Vauclin, PhD, Product Manager, DOSIsoft SA, Cachan, France.

Annabelle Lorenzo, MS, Application Engineer, DOSIsoft, Inc. Miami, FL

Marilyne Kafrouni, PhD Candidate, Montpellier University Hospital, France (Nuclear Medicine Department)