Nuclear Medicine Therapy
The General Principle of Nuclear Medicine Therapies
Nuclear Medicine Therapies operate through two different mechanisms: either the administered radioactive substance is processed normally in metabolism (e.g., Iodine-131, like regular iodine in the thyroid) or the radioactive substances are coupled to binding molecules (ligands) that in turn bind to specific cellular target structures (radio-ligand therapy). In both cases, a high dose of radioactive radiation is specifically delivered to a particular tissue, capable of destructing the tissue from within.
For therapy, so-called beta-minus emitters are used. These substances emit electrons upon their decay, which have a range of only a few millimeters in tissue and can cause damage and destroy tissue along their path. No damage is expected in tissues where the target molecules are absent; however, there may be side effects from adjacent tissues.
Our Therapy Ward
Our therapy ward has all the prerequisites for the application of all nuclear medicine therapies. These include radioiodine therapies for benign thyroid diseases or thyroid carcinoma, PSMA therapies for prostate carcinoma, DOTATATE therapies for neuroendocrine tumors and selective internal radiotherapy (SIRT) for the treatment of liver metastases.
We also offer other innovative therapies for various oncological diseases.
You will be accommodated in modern 2-bed rooms with bathrooms and in good weather you can sit in the park or go for a walk.
Radioiodine Therapy for benign thyroid diseases
Principle
In the course of certain thyroid diseases, such as nodular goiter with functional autonomy and hyperfunction of various origins, various treatment options often arise, which may be used alternatively, in combination, or sequentially: medicinal therapy, surgical therapy, and radioiodine therapy. For both the diagnosis and treatment planning of thyroid diseases, as well as for assessing treatment success, the use of nuclear medicine methods is necessary.
Radioiodine therapy is performed using the radioactive substance iodine-131. Radioactive iodine-131 behaves in the body like normal iodine and is taken up by the thyroid gland for the production of thyroid hormones. In cases of autonomous thyroid diseases (unregulated high production of thyroid hormones), the radioactive iodine is selectively taken up by the overactive areas and destroys the faulty tissue from within using radiation.
When is radioiodine therapy performed?
- Thyroid hyperfunction in Graves' disease
- Autonomy of the thyroid gland
- Recurrence of thyroid hyperfunction after surgery
- Impossibility of thyroid surgery or intolerance to thyroid-blocking medications
Regarding the benefits of medicinal therapy, surgery, or radioiodine therapy, we are also happy to advise you in our thyroid outpatient clinic.
Before radioiodine therapy, an outpatient radioiodine test is performed to determine if and to what extent the thyroid gland absorbs radioiodine. This helps determine the necessary therapy activity. For this test, a small capsule with a very low activity of iodine-131 is administered for swallowing. The next day, a measurement is taken to determine how much of the radioactive iodine was absorbed by the thyroid gland. Additional measurements may be scheduled on the first day of examination.
Avoiding iodine contamination is strictly necessary within 3-6 months before undergoing radioiodine therapy (especially iodine-containing contrast agents and iodine-containing medications). In Germany, for radioiodine therapy to be carried out, admission to a special nuclear medicine therapy unit with a minimum 48-hour stay is required. Depending on the size and activity of the thyroid gland, a longer hospital stay (one week or more) may be necessary for radiation protection reasons. Unfortunately, the actual length of stay cannot be reliably predicted before therapy. Iodine-131 is usually administered as a capsule or, in rare cases, as a liquid.
Therapy Success
Therapeutic success occurs after 3-4 months. During this period, regular laboratory checks of thyroid parameters are required, and thyroid-specific medication may need to be modified or started anew if necessary. Radioiodine therapy typically results in a reduction of thyroid gland size by approximately 30% in enlarged goiters. Radioiodine therapy for benign thyroid diseases is an extremely effective therapeutic approach with no significant side effects and no measurable long-term effects. It is also safe for young patients. Due to the small amount of iodine administered, radioiodine therapy can also be performed in cases of rare true iodine allergy. In Germany, radioiodine therapy must be conducted in a hospital setting for radiation protection reasons.
Radioiodine Therapy for malignant thyroid diseases
Principle
Iodine-131 accumulates in thyroid carcinomas where the ability to store radioiodine is retained (differentiated thyroid carcinomas). The prerequisite for radioiodine therapy in thyroid cancer is the prior total surgical removal of the thyroid gland. Only after the largely complete removal of normal thyroid tissue can sufficient accumulation of iodine-131 in storing residual tumor tissues and metastases be achieved. Radioiodine therapy for thyroid cancer is differentiated between prophylactic irradiation of the residual thyroid gland post-surgery (ablation) and targeted therapy for recurrent thyroid cancer and metastases.
Radioiodine therapy is performed using the radioactive substance iodine-131. Radioactive iodine-131 behaves in the body like normal iodine and is taken up by the thyroid gland for the production of thyroid hormones. Radioactive iodine is absorbed into the tumor and destroys the tissue from within using radiation.
When is radioiodine therapy performed for malignant thyroid diseases?
- Ablation after thyroid surgery
- Therapy for iodine-storing recurrences and metastases
- Tumor surveillance with rising levels of thyroglobulin (thyroid protein)
- Impossibility of thyroid surgery or intolerance to thyroid-blocking medications
For the therapy, admission to a specialized nuclear medicine therapy unit is required (minimum 48 hours). The therapy activity is usually administered in capsule form (3,700 to 7,400 MBq iodine-131). The therapy is conducted under a medication-based stomach protection regimen. In the first 2-3 days after capsule administration, it is recommended to frequently suck on sour candies or chew gum and drink plenty of fluids to stimulate saliva flow adequately and prevent late damage to the salivary glands.
Before the Procedure
- Discontinuation of thyroid-specific medications at least 4 weeks before therapy • Avoidance of iodine contamination (especially iodine-containing contrast agents)
PSMA Theraphy for Prostate Cancer
Principle
Prostate cancer is a tumor disease of the prostate gland. PSMA (Prostate-Specific Membrane Antigen) is a surface molecule that is frequently present on prostate tumors and acts as a receptor. The radioactive substances Lutetium-177 or Yttrium-90 are coupled to binding molecules that, after injection, can specifically bind to PSMA. Through high-energy radiation, these substances can then selectively destroy the tumor and its metastases.
Before therapy, diagnostic imaging of PSMA is performed using PET, which enables precise visualization of the distribution of PSMA-positive prostate cancer and how the radioactive substance will accumulate during therapy.
When is PSMA therapy performed?
PSMA therapy is currently used in cases of metastatic, hormone-resistant prostate cancer when other treatment options, such as chemotherapy and hormone therapy, have been exhausted. An important prerequisite is the presence of PSMA on the cell surface, which is verified prior to therapy.
Procedure
PSMA therapy is preferably carried out with Lu-177-PSMA in our therapy ward during an inpatient stay of several days. In total, up to 6 therapy cycles are usually possible at intervals of 4–6 weeks, provided the treatment is well tolerated.
Before PSMA therapy, a thorough examination by our physicians is required, as well as a prior PET/CT with Ga-68-PSMA to assess PSMA expression in the tumor metastases and to confirm eligibility for the therapy. In addition, further laboratory tests are necessary to check bone marrow function (blood count) and kidney function. If required, a MAG3 scintigraphy is performed to evaluate kidney function and to rule out urinary outflow obstruction.
The therapy is administered in our therapy ward through a previously inserted intravenous catheter. In addition, you will receive a fluid infusion to protect the kidneys, and the salivary glands are cooled to reduce the accumulation of the radioactive substance and thereby minimize related damage.
After the therapy, a further PET scan is performed to demonstrate and document the distribution of the dose. Because of the administration of the radioactive substance during the therapy, your body will emit radiation. This is measured daily, and discharge takes place once the radiation level has fallen below the legally defined limit.
During the course of the therapy, regular blood tests and imaging examinations are performed for follow-up and therapy monitoring.
What Do I Need to Keep in Mind?
After receiving the therapy, you should drink plenty of fluids to support kidney function and the excretion of the radioactive substance.
Selective Internal Radiation Therapy (SIRT) for Hepatocellular Carcinoma und Liver Metastases
Principle
Selective Internal Radiation Therapy (SIRT) is used for advanced forms of primary liver tumors. For this treatment, several million tiny beads, labeled with the beta emitter Yttrium-90 or Holmium-166, are delivered directly into the tumor region in the liver via catheter through the blood vessels. These radioactive beads become trapped in the tumor's vascular network and destroy the tissue from within.
To assess the achievable activity within the tumor during treatment, a trial run with weakly radioactive Tc-99m must be conducted prior to therapy. Additionally, there may be additional vascular connections to the lungs or intestines in the tumor area. The preliminary examination also rules out any serious side effects from these undiscovered connections during treatment.
When is SIRT performed?
SIRT is used in hepatocellular carcinoma or cholangiocarcinoma when these cannot be treated surgically or when no local or systemic therapies are available. In addition, non-operable liver metastases from other types of cancer may, in certain cases, also be treated with SIRT.
Procedure
SIRT is carried out in cooperation with interventional radiology. First, the blood supply of the liver and the tumor is visualized by means of angiography. Before the actual therapy, a test run with weakly radioactive Tc-99m is performed, and its distribution is then displayed in the SPECT/CT. This allows the uptake of the substance by the tumor to be assessed in advance, and possible vascular connections to the gastrointestinal tract or lungs can be identified and, if necessary, closed, as these could otherwise lead to serious side effects during therapy.
Subsequently, the therapy is administered through the same catheter directly into the tumor region. After the therapy, an additional scintigraphy is performed to visualize and document the distribution of the microspheres. Because of the administration of the radioactive substance as part of the therapy, your body will emit radiation. This is measured daily, and discharge takes place once the radiation level has fallen below the legally defined threshold.
Peptide Recetor Radionuclide Therapy for Neuroendocrine Tumors
Principle
Neuroendocrine tumors consist of cells that bear somatostatin receptors on their cell walls, which are binding sites for specific hormones. Nowadays, it is possible to artificially produce variants of the hormone somatostatin. For the planned therapy, DOTATOC or DOTATATE is loaded with radioactive lutetium-177 or yttrium-90, which bind specifically to somatostatin receptors and can selectively kill tumor cells.
Procedure
PRRT is carried out in our therapy ward during an inpatient stay of several days. In total, 4 therapy cycles are usually performed at intervals of approximately 3 months. Additional cycles may be possible if necessary.
Before PRRT, a thorough examination by our physicians is required, as well as a PET scan with Ga-68-DOTA to visualize the tumor mass and confirm suitability for the therapy. In addition, a blood test is performed to check bone marrow function (blood count) as well as liver and kidney values.
The therapy is administered in our therapy ward through a previously inserted intravenous catheter. Parallel to the therapy, an amino acid infusion is given to protect the kidneys. DOTATOC or DOTATATE are peptide compounds that, after being excreted in the urine, are reabsorbed by the kidneys like other peptides. This would otherwise expose the kidneys to higher radiation from the bound radioactive substances. The amino acids in the infusion inhibit this reabsorption and thereby minimize potential kidney damage.
After the therapy, another PET scan is performed to demonstrate and document the distribution of the dose. Because of the administration of the radioactive substance as part of the therapy, your body will emit radiation. This is measured daily, and discharge takes place once the radiation level has fallen below the legally defined threshold.
Therapy of Neuroblastoma and Pheochromocytoma
Principle
Neuroblastoma is a malignant childhood tumor of the autonomic nervous system (sympathetic and parasympathetic) originating from embryonal cells in sympathetic tissue. Pheochromocytoma is also a malignant tumor arising from chromaffin cells of the adrenal medulla. Both tumors strongly express norepinephrine transporters on their surface, which serve as the target molecule for tumor therapy.
For this purpose, metaiodobenzylguanidine (mIBG) is coupled with the radioactive iodine-131 (I-131). mIBG is an analogue of norepinephrine (noradrenaline) and is specifically taken up and stored by tumor cells via the norepinephrine transporter. I-131 is a therapeutic beta emitter that can destroy the tumor from within by delivering high-energy radiation.
When is I-131-mIBG therapy for neuroblastoma performed?
The therapy can be administered after chemotherapy and before stem cell transplantation, provided residual tumor burden carrying the norepinephrine receptor can still be detected with mIBG.
I-131-mIBG therapy may also be used in cases of recurrence or as part of palliative pain management.
When is I-131-mIBG therapy for pheochromocytoma performed?
I-131-mIBG therapy can be used in cases of metastatic pheochromocytoma
Procedure
The therapy is carried out in our therapy ward during an inpatient stay of several days. Typically, 1–2 therapy cycles are performed. Before the therapy, a scintigraphy with I-123-mIBG is conducted to visualize the tumor and to confirm suitability for the treatment.
The therapy is administered through a previously inserted intravenous catheter under continuous blood pressure and ECG monitoring. In addition, Irenat® drops are given to protect the thyroid gland. The thyroid uses iodine to produce thyroid hormones and could also take up radioactive I-131 that may detach from I-131-mIBG, potentially causing damage. Irenat prevents this uptake, as the sodium perchlorate it contains competes with iodide at the transporter level and thereby blocks absorption into the thyroid.
Furthermore, a fluid infusion is administered to protect the kidneys, supporting kidney function and the excretion of the radioactive substance from the body.
After the therapy, another scintigraphy is performed to visualize and document the distribution of the dose. Because of the administration of the radioactive substance as part of the therapy, your body will emit radiation. This is measured daily, and discharge takes place once the radiation level has fallen below the legally defined threshold.
What Do I Need to Keep in Mind?
If necessary, certain medications may need to be discontinued. Please send us a list of your current medications so that we can discuss the appropriate measures.
After receiving the therapy, you should drink plenty of fluids to support kidney function and the excretion of the radioactive substance.
Radiophosphorus Therapy for Disorders of the Hematopoietic Bone Marrow
Principle
In certain disorders of the hematopoietic bone marrow (polycythemia vera and essential thrombocythemia), radiophosphorus therapy may be considered. In polycythemia vera, there is abnormal production of red blood cells without a stimulus, while in essential thrombocythemia there is excessive production of platelets.
Phosphorus-32 (P-32) is a therapeutic beta emitter that is metabolized by the body like “normal” phosphorus. It is particularly required in proliferating tissue for the synthesis of nucleic acids for DNA and therefore accumulates in high amounts in the rapidly dividing cells of polycythemia vera and essential thrombocythemia. This allows the radioactive P-32 to concentrate locally and destroy these cells through high-energy radiation.
Additionally, P-32 is involved in bone metabolism and also accumulates near the bone marrow, thereby irradiating it directly. If cell lines proliferate outside the bone marrow, these will also be affected by the therapy.
When is it performed?
Radiophosphorus therapy can be performed in cases of polycythemia vera and essential thrombocythemia when other treatment options have been exhausted.
Procedure
Before the therapy, a blood test and kidney function check are performed. The therapy is administered through a previously inserted intravenous access.
Radioimmunotherapy for B-Cell-Lymphoms
Principle
Radioimmunotherapy is used in B-cell lymphomas. B-cell lymphomas are tumors that develop from malignant transformation of B cells, a subgroup of the cellular immune system. These cells usually express the surface molecule CD20, which serves as a marker for B cells. This molecule is the target for immunotherapy with the anti-CD20 antibody rituximab, which is used in combination with chemotherapy.
In radioimmunotherapy, the concept of immunotherapy is combined with targeted radiation therapy of the malignant cells by coupling Yttrium-90 (Y-90), a therapeutic beta emitter, to a CD20 antibody. This approach also kills neighboring cells through radiation effects, thereby extending the therapeutic reach.
When is it performed?
Radioimmunotherapy is used in follicular non-Hodgkin lymphoma when rituximab therapy does not achieve the desired effect or when a relapse occurs after rituximab treatment. The therapy may also be used in cases of tumor recurrence following chemotherapy.
Procedure
Before the therapy and on the day of the therapy, rituximab is administered twice via an intravenous access to block the CD20 molecules on healthy B cells and thereby protect them as much as possible.
This is followed by the infusion of the radioactively labeled antibodies.
Therapy of Bone Metastases
Principle
The bones are a common site for tumor metastases, which is often associated with pain. Palliative treatment of these metastases using nuclear medicine techniques can help reduce pain. In bone metastases, a distinction is made between osteolytic (bone-destroying) and osteoblastic (bone-forming) metastases. Nuclear medicine therapy is only effective for osteoblastic metastases, which are especially common in prostate and breast cancer.
In our clinic, the alpha emitter radium-223 (Ra-223) and the therapeutic beta emitter samarium-153-EDTMP (Sm-153-EDTMP) are used. Ra-223 behaves metabolically like calcium, which is important for bone formation, and is incorporated directly into the bone. Similarly, Ra-223 is incorporated into the bone and can locally deliver high-energy radiation through the emission of alpha particles. Sm-153 is bound to the bisphosphonate EDTMP, which binds to the bone surface, particularly in areas of bone remodeling as found in osteoblastic metastases. The radioactive Sm-153 thus accumulates in the tumor area and can locally deliver high-energy radiation.
The radiation primarily destroys inflammatory cells in these areas and inhibits the release of pro-inflammatory mediators from immune and tumor cells. The radiation can also directly kill tumor cells.
When is it performed?
Nuclear medicine therapy for bone metastases is generally used when numerous osteoblastic bone metastases occur that no longer respond to conventional pain therapy, or when a reduction in the current pain medication dose is desired. Ra-223 is specifically used in advanced castration-resistant prostate cancer with symptomatic bone metastases.
Procedure
Before the therapy, a skeletal scintigraphy is performed to visualize bone metabolism in the area of the metastases and to confirm suitability for treatment. In addition, a blood test is carried out.
The therapy is administered through a previously inserted intravenous catheter and can also be performed on an outpatient basis. Pain relief often occurs within a few days and can last for several weeks.
After administration of Sm-153-EDTMP, a scintigraphy is performed to show the distribution and dose of the substance. For Ra-223, a total of 6 therapy cycles are possible at intervals of approximately 4 weeks.
Radiosynoviorthesis
Principle
Radiosynoviorthesis is a therapeutic option for inflamed and hypertrophied joint synovium, as occurs in chronic inflammatory joint diseases. Various beta emitters are used in the therapy: Yttrium-90 (Y-90) for large joints, Rhenium-186 (Re-186) for medium-sized joints, and Erbium-169 (Er-169) for small joints. The substances are injected directly into the joint via a needle and taken up by synovial cells and immune cells in the joint. The radiation causes scarring of the synovial membrane, inhibits cell proliferation, and destroys the cells. This aims to reduce inflammation and alleviate pain.
When is radiosynoviorthesis performed?
Radiosynoviorthesis is performed in chronic inflammatory joint diseases.
Procedure
The therapy is performed on an outpatient basis in our clinic. A preliminary examination by our physicians is conducted, and the joint is visualized. The radioactive substance is then injected directly into the joint.
After the treatment, the joint must be immobilized for 48 hours to prevent the substance from being displaced and to allow it to act locally. The therapeutic effect usually occurs within a few weeks, but in some cases may take several months to become noticeable.