Precision cancer therapy with radiation beams and organ protection.

Precision Dose: How New Methods Are Improving Cancer Therapy

Nico Varela in Health & Wellness December 2025 • 4 min read.

"Dosimetry procedures for organs-at-risk in peptide receptor radionuclide therapy with lutetium-177 are transforming cancer treatment."

Molecular radiotherapy (MRT) is increasingly relying on precise dosimetry to tailor treatments and improve outcomes. Standardizing dosimetry procedures is crucial for maximizing therapeutic benefits and minimizing harm. A key challenge lies in determining the optimal range of absorbed doses that effectively target tumors while safeguarding organs-at-risk (OAR).

Developing standardized dosimetry methods in molecular radiotherapy presents multifaceted challenges, encompassing drug administration, data acquisition, activity quantification, and absorbed dose computation. Each step introduces variables that impact the accuracy and reproducibility of results. Effective implementation requires careful consideration of patient burden, practicality, cost-effectiveness, and the reliability of obtained data.

In the context of lutetium-177 (¹⁷⁷Lu) peptide receptor radionuclide therapy (PRRT), various approaches have been explored to refine dosimetry. These include phantom studies for improved imaging, adjustments to time-point measurements, kinetic and radiobiological modeling, and organ- and voxel-scale dosimetry based on Monte Carlo simulations. This article will discuss how these strategies improve cancer therapy.

Enhancing Precision in Dosimetry: A Multi-Step Approach

Precision cancer therapy with radiation beams and organ protection.

A recent study detailed a dosimetry procedure for organs-at-risk during ¹⁷⁷Lu-DOTATATE therapy, involving 47 patients with neuroendocrine tumors (NETs). The process integrates SPECT/CT imaging with blood sample analysis to enhance accuracy and minimize patient discomfort.

The key steps in this improved dosimetry procedure include:

Drug Administration: Administering lutetium-177 based radiopharmaceuticals.
Data Acquisition: Serial SPECT/CT images were obtained at 4, 24, and 168 hours post-injection. Blood samples were taken at similar time points, along with additional samples within the first hour to capture early clearance.
Activity Quantification: PMOD software was used to measure volumes and activity concentrations in kidneys, spleen, liver, red marrow, and the remainder of the body, using volumes of interest (VOIs) on SPECT/CT images.
Dose Computation: Time-integrated activity coefficients (TIACs) were calculated using bi-exponential fits, and OLINDA/EXM software was used to compute absorbed doses to organs-at-risk.

This comprehensive approach facilitates accurate measurement of activity concentrations and absorbed doses, crucial for assessing the impact on organs-at-risk and optimizing treatment strategies.

Future Directions in Personalized Cancer Treatment

The described dosimetry procedure offers a practical approach for routine clinical implementation, balancing accuracy with patient comfort. Results from this study align with findings from other research centers, reinforcing the reliability and applicability of the method.

By standardizing dosimetry procedures, researchers and clinicians can better understand the relationship between radiation dose and therapeutic outcomes, potentially leading to more individualized and effective treatments. Collaborative efforts to share and refine these techniques will further enhance the precision and safety of molecular radiotherapy.

As dosimetry methods become more refined and accessible, personalized cancer treatment strategies will become a reality, promising improved outcomes and reduced side effects for patients undergoing radionuclide therapy.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.ejmp.2018.11.001, Alternate LINK

Title: A Dosimetry Procedure For Organs-At-Risk In 177Lu Peptide Receptor Radionuclide Therapy Of Patients With Neuroendocrine Tumours

Subject: General Physics and Astronomy

Journal: Physica Medica

Publisher: Elsevier BV

Authors: Gwennaëlle Marin, Bruno Vanderlinden, Ioannis Karfis, Thomas Guiot, Zena Wimana, Nick Reynaert, Stefaan Vandenberghe, Patrick Flamen

Published: 2018-12-01

Everything You Need To Know

What is precision dosimetry, and why is it important in cancer therapy?

Precision dosimetry in cancer therapy involves accurately measuring the radiation dose absorbed by organs-at-risk (OAR) during treatments like lutetium-177 (¹⁷⁷Lu) peptide receptor radionuclide therapy (PRRT). This is essential for maximizing the therapeutic benefits by targeting tumors effectively while minimizing harm to healthy tissues. The goal is to tailor the treatment to each patient, improving outcomes and reducing side effects.

What is Lutetium-177 (¹⁷⁷Lu) and how is it used in cancer treatment?

Lutetium-177 (¹⁷⁷Lu) is a radioactive isotope used in peptide receptor radionuclide therapy (PRRT), a type of molecular radiotherapy (MRT). The ¹⁷⁷Lu is attached to a peptide that targets specific receptors on cancer cells, such as those found in neuroendocrine tumors (NETs). This allows the radiation to be delivered directly to the tumor cells, reducing exposure to healthy tissues. The use of ¹⁷⁷Lu in this context allows for the delivery of targeted radiation therapy.

What are organs-at-risk (OAR) in the context of radiation therapy, and why do we care about them?

Organs-at-risk (OAR) are healthy tissues and organs near the tumor that can be affected by radiation during cancer treatment. In the context of dosimetry, it's critical to measure the radiation dose these organs receive to minimize potential side effects. The key OAR in lutetium-177 (¹⁷⁷Lu) peptide receptor radionuclide therapy (PRRT) include the kidneys, spleen, liver, and red marrow. The precision in dosimetry helps in creating strategies to protect them.

What are the key steps involved in the dosimetry procedure?

The key steps of the dosimetry procedure are Drug Administration, Data Acquisition, Activity Quantification, and Dose Computation. In Data Acquisition, serial SPECT/CT images are obtained at specific time points after injecting the lutetium-177 (¹⁷⁷Lu) based radiopharmaceuticals, alongside blood samples at the same time points. Activity Quantification uses software, such as PMOD, to measure activity concentrations in organs-at-risk. The Dose Computation involves calculating Time-Integrated Activity Coefficients (TIACs) and using software such as OLINDA/EXM to compute absorbed doses. This multi-step approach enables accurate measurement and assessment of radiation exposure, crucial for effective cancer therapy.

Why is accurate dosimetry so important in cancer treatment, and how does it affect patient outcomes?

Accurate dosimetry is significant because it allows for personalized medicine. By measuring and calculating the absorbed doses in the organs-at-risk (OAR) during lutetium-177 (¹⁷⁷Lu) peptide receptor radionuclide therapy (PRRT), doctors can optimize the treatment. This involves tailoring the radiation dose to maximize tumor control while minimizing damage to healthy tissues. Standardization of the dosimetry protocols is very important for ensuring that treatments are both effective and safe. It allows the medical staff to adjust and improve the treatments, leading to better outcomes and reduced side effects for patients.