INTRODUCTION TO NUCLEAR MEDICINE ONCOLOGY.pptx

Nuclear medicine is a medical specialty that uses radioactive tracers (radiopharmaceuticals) to assess bodily functions and to diagnose and treat disease. Specially designed cameras allow doctors to track the path of these radioactive tracers.

1. NUCLEAR MEDICINE Dr Venkateshen Palanisamy Dept of Surgical Oncology

2. What is Nuclear medicine Nuclear medicine is a imaging modality uses radioactive material inside the body to see how organs or tissue are functioning (for diagnosis) T o target and destroy damaged or diseased organs or tissue (for treatment).   P hysiological information about the tissues

3. HISTORY OF RADIOPHARMACY The first radiotherapeutics: United States in the late 1930s, when the first use of sodium iodide- 131 was introduced by Hamilton and Soley In 1951 Sodium iodide- 131 became the first radiopharmaceutical approved by the US Food and Drug Administration (FDA) for use in thyroid patients The first Single Photon Emission Computed Tomography (SPECT) radiopharmaceutical: One of the most important developments in radiopharmacy was in the early 1960s with the clinical introduction of 99mTc generators for the preparation of radiopharmaceuticals by Powell Richards at Brookhaven National Laboratory. Positron Emission Tomography (PET) cameras are available in the 1980s’.

4. N UCLEAR MEDICINE Radiopharmaceutical administered E xternal radiation detectors D iagnosis Prognosis Staging T reatment I n vivo distribution and dynamics of the radiopharmaceutical

5. Radio- pharmeceutical An unstable atom that undergoes radioactive decay in order to achieve stability is known as a radionuclide A drug that contains a radioactive substance and is used to diagnose or treat disease The radiation emitted by the radionuclide may be detected from outside the body by a radionuclide imaging device (a gamma camera) M ay be detected in a sample of a body fluid (e.g. plasma or urine)

6. Routes of administration - Radiopharmeceutical Intravenous injection (Most common) Intraarterial Subdermal gastrointestinal tract the breathing of a radioactive gas or aerosol

7. Mechanism T he enhanced uptake of the radiopharmaceutical in certain tissues (the uptake of fluorodeoxyglucose [FDG] in tumors) - hot-spot other cases it may be the lack of uptake (e.g., the absence of Tc-99m sestamibi in infarcted myocardium). - cold-spot

8. UPTAKE

9. COLD REGIONS

10. In other situations it may be the rate of uptake (wash in) or clearance (wash out) that may be considered the essential characteristic of the study. In a Tc-99m mercaptoacetyltriglycine (MAG3) renal study, fast wash in may indicate a well-perfused kidney, and delayed clearance may indicate renal obstruction. In the Tc-99m DTPA counting protocol described previously, a slow clearance of the radiopharmaceutical from the blood would indicate a reduced GFR.

11. Detectors To characterize the rate, location, and magnitude of radiopharmaceutical uptake within the patient the emitted radiation must be detected in most cases by detectors external to the patient’s body. Some instruments are specially designed for internal use—for example, interoperative radiopharmaceutical imaging—but in most the cases, the imaging device is located outside the body while detecting radiation internally. This requirement limits the useful emitted radiations for nuclear medicine imaging to energetic photons —that is, gamma rays and x-rays.

12. Ideal RAYS The amount of overlying tissue between the internally distributed radiopharmaceutical and the radiation detector may vary from several centimeters to as much as 20 to 30 cm. Alpha and beta particles will not be of use in most cases because their ranges in tissue are limited to a few millimeters, and thus they will not exit the body and cannot be measured by external radiation detectors.

13. Even x-rays and gamma rays must have energies in excess of 50 keV to penetrate 10 cm of tissue. On the other hand, once the radiation exits the patient, it is best that the radiation not be so energetic as to be difficult to detect with reasonable-size detectors. Thus the radiation types optimal for most nuclear medicine imaging applications are x-rays and gamma rays in the 50- to 300-keV energy

14. DECTORS GAMMA CAMERA - IODINE SCAN A  single-photon emission computerized tomography  (SPECT)  A positron emission tomography (PET) - sensors

15. THYROID SCAN S table iodine (I-127) normally encountered in the diet R adioactive iodine isotopes such as I-131 or I-123 Gamma camera

16. Mechanism of thyroid scan In the proximal small bowel more than 90% of ingested iodine is absorbed r apidly It is detectable in the thyroid within minutes of oral ingestion R eaching the thyroid follicular lumen by 20 to 30 minutes Thyroid uptake normally continues to increase over 24 hours I maging can be done as soon as 4 hours.

17. The delay between radioiodine administration and imaging is not due to slow accumulation but rather the time needed to clear relatively high background activity. Radioiodine uptake can also be seen in the salivary glands, stomach, and choroid plexus; however, it is not concentrated or retained there. Excretion is via the kidneys and gastrointestinal tract.

18. I 123 I-123 decays by electron capture (13.2-hour half-life) P rincipal emission is a 159-keV gamma photon (83.4% abundance), well suited for gamma camera imaging the lack of β- emissions - the radiation dose to the patient is roughly 100 times less than I-131 (10 rads/ mCi ) compared with 1000 rad/ mCi . The standard uptake dose is 100 μCi to 200 μCi for routine thyroid scans. Higher doses can also be used in cancer imaging because I-123 does not cause stunning.

19. I -131 I-131 undergoes beta-minus decay ( β–) Emitting a principal primary gamma photon of 364 keV An 8.1-day physical half-life These photons are not ideal for gamma camera imaging. Count detection sensitivity is poor. High-energy β- particles (0.606 megaelectron volt [MeV]) are also emitted, which cannot be imaged but are valuable for therapy.

20. I 124 I-124 is a positron emitter that has been used as an alternative to I 123 or I-131 for thyroid cancer imaging It is cyclotron produced, decays by electron capture (75%) and positron decay (26%), and has a half-life of 4.18 days Emitting a principal primary gamma photon of 511 keV Studies suggest it is superior to I-123 or I-131 for the detection of thyroid cancer metastases L argely in an experimental capacity.

21. Tc-99m pertechnetate I nexpensive and readily available, unlike the costlier I-123, Because it is taken up by the same mechanism as iodine, Tc-99m pertechnetate can be used for thyroid assessment. The 140-keV photopeak (89% abundance) and lack of high-energy emissions are optimal for gamma camera imaging In contrast to oral administration of radioiodine, Tc- 99m pertechnetate is administered intravenously and rapidly taken up However, it is not organified or retained in the thyroid, and imaging must be performed early at peak uptake time, 15 to 30 minutes after injection. The lack of particulate emissions and short 6-hour half-life result in a low radiation dose to the thyroid, far less than I-131 or I-123. the large photon flux which results in high-quality images.

22. Indications

23. Thyroid Scan – Diagnostic Iodine-123 is administered orally and the scan is acquired 4 hours later. Imaging at 24 hours Four-hour images have superior image quality. Tc-99m pertechnetate can also be administered intravenously, and scan acquisition begins 20 minutes later.

24. Procedure

25. Pinhole collimator

26. Summary Patient Preparation Discontinue medications that interfere with thyroid uptake Nothing by mouth for 4 hours before study. Radiopharmaceutical Iodine I-123, 200 to 400 μ Ci (3.7–14.8 MBq), orally in capsule form (or) Tc-99m pertechnetate, 3 to 5 mCi (111–185 MBq), intravenously

27. Time of Imaging Iodine I-123, 4 hours after oral dose administration Tc-99m pertechnetate, 20 minutes after injection Imaging Procedure Gamma camera with pinhole collimator Position the supine patient with the chin up and neck extended. Acquire anterior, left anterior oblique, and right anterior oblique images for equal time compared with anterior view.

28. Normal thyroid scan

29. Graves

30. Multi nodular goitre

31. Hot nodule Toxic follicular adenomas

32. Cold nodule Benign Colloid nodule Simple cyst Hemorrhagic cyst Adenoma Abscess Parathyroid cyst or adenoma Malignant Papillary Follicular Hurthle cell Anaplastic Medullary Lymphoma Metastatic carcinoma Lung Breast Melanoma Gastrointestinal

33. Warm nodules Nontoxic hyperfunctioning adenomas Hyperplastic thyroid tissue

34. Post thyroidectomy Scan Preparation Two methods are used for patient preparation. In one, the patient is not prescribed thyroid hormone replacement/suppression postoperatively; the serum TSH progressively rises as the patient becomes increasingly hypothyroid. The patient’s serum TSH level should be greater than 30 U/mL before radioiodine is administered, to ensure good uptake. This takes 4 to 6 weeks. Alternatively, the patient is placed on replacement/suppression thyroid hormone after surgery. Then Thyrogen , a recombinant form of TSH ( rTSH ), is administered on 2 consecutive days as an intramuscular injection of 0.9 mg. A serum TSH level is usually obtained. On the third day, radioiodine is administered. Imaging is performed on day 4 for I-123 and day 5 for I- 131.

35. Ablation – I 131 Physical half-life of 131 I is 8.02 days. Mainly emit B rays– 90% of radioactivity of 131 I Gama-radiation contributes only 10% of the total radiation dose 131 I is available for oral ingestion as sodium iodine Most of the radiation dose is delivered by B particles

36. Iodine therapy Graves disease and malignancy . Full effectiveness may take 3 to 6 months. A small minority of patients require repeat treatment (<10%) with a higher administered dose. Precautions Pregnancy must be excluded before I-131 therapy. Women should be counseled to avoid pregnancy for 3 to 6 months after therapy in the event that retreatment is necessary

37. SPECT SCAN

38. SPECT Single Photon Emission Computed Tomography is a Nuclear Medicine imaging modality, which involves the use of radionuclides injected intravenously into the body, to produce a 3D distribution of the gamma rays emitted by the radionuclide, giving physiological information about the organ of interest SPECT uses single photons

39. It uses 1 or more gamma camera heads rotated round the patient. SPECT combines conventional scintigraphic and computed tomographic methods.

40. GAMMA CAMERAS In the mid-1950s, Hal Anger developed his first prototype of the gamma camera

41. Collimator

42. A radiopharmaceutical is injected into the patient’s body. It travels into the blood stream, and concentrates in the Region of Interest. There, it decays, emitting gamma rays. The gamma rays travel out of the patient’s body, and are detected by the gamma camera head of the SPECT machine. The gamma ray is collimated by the collimators to minimize scatter, and improve image quality

43. SESTAMIBI SPECT imaging has also found great utility in the field of cardiovascular disease Particularly in the assessment of myocardial perfusion during stress testing. Tc is bound via coordination complex to 6 methoxyisobutylisonitrile (MIBI) groups to form a tracer compound known as sestamibi .

44. Commonly used tracers

45. Ideal tracers A physical half life of few hours Decay to a stable daughter Emit gamma rays but no alpha or beta or very low energy photons Emit gamma rays of energy 50-300KeV Ideally emit monoenergetic gamma rays so that scatter can be eliminated by PHA Be easily and firmly attached to the pharmaceutical at room temp Have a very high Specific activity Have a very Low toxicity

46. Tc- 99 Tc has a half-life of 6 hours and high photon flux, leading to shorter scan times and lesser radiation exposure to the target organ. This allows for the administration of higher tracer doses, providing clear images without significantly increasing radiation exposure to the patient

47. Bone scan - SPECT  Radiotracer Technetium-99m (Tc99m) complexed to a diphosphonate Methylene diphosphonate (MDP) forming Tc99m-MDP H ydroxy diphosphonate (HDP) forming Tc99m-HDP

48. Sentinel Node Mapping With Lymphoscintigraphy Tc-99m sulfur colloid (SC) Tc-99m tilmanocept

49. PET SCAN

50. PET – POSITRON EMISION TOMOGRAPHY PET uses a method called annihilation coincidence detection to acquire data over 360 degrees without the use of absorptive collimation. performed on a dedicated PET camera combining the CT or magnetic resonance imaging (MRI) scanner in a single hybrid PET/CT or PET/MR device.

51. Physics- Annihilation

52. True coincidence

53. Errors in PET SCAN

54. F-18 Fluorine Deoxyglucose (F-18 FDG) Cancer: Staging, restaging, therapy monitoring Lung nodule diagnosis/characterization, localization of cancer of unknown primary Dementia imaging Seizures (interictal) Cardiac: Viability, sarcoidosis

55. Normal distribution Normal distribution of F-18 fluorodeoxyglucose (FDG). Uptake is normally intense in the brain and urinary tract, moderately intense in the liver, and variable in muscles (especially of the oropharynx), heart, and bowel. Normal variants. Marked uptake can be seen normally in the small and large bowel. In some cases, the increased bowel activity is related to metformin use.

56. Prepare the patient Avoid exercise for 1 to 2 days. Diabetes: Serum glucose controlled Insulin: Stop long-acting insulin 8 to 12 hours before scan; no short-acting insulin within 2 hours of injection. Oral metformin (Glucophage): May continue If colon is area of concern, consider holding 48 hours if serum glucose can be controlled otherwise. Hydrate patient orally. NPO except water for 4 to 6 hours; avoid carbohydrates 6 to 24 hours prior; no caffeine. Check serum glucose before dosing (<200 mg/dL). Patient kept warm, quiet, and relaxed for 30 to 60 minutes before injection. Consider sedation (diazepam, benzodiazepine) for claustrophobia, anxiety or tense muscles, or prior head and neck surgery. Prior brown-fat uptake: Warming the patient is best. Alternative: 5 mg intravenous (IV) diazepam 10 minutes prior or 80 mg oral propranolol 2 hours prior

57. Normal areas of uptake Brain Pharyngeal and Parapharyngeal – salivary glands Myocardial Metabolism Urinary Excretion Gastrointestinal Tract Marked uptake in the bowel can occur from metformin. Inflammation, such as from colitis, inflammatory bowel disease, appendicitis, and diverticulitis

58. Brown Adipose Tissue Activation

59. Quantification: The Standard Uptake Value (SUV) Lesion activity can be described in comparison to contralateral background, blood pool, or liver activity. Areas can be graded as mild, moderate, or marked depending on the level compared with normal structures. It is often desirable to use a numerical value and this is usually done with the standard uptake value, or SUV an SUV greater than 2.5 has been considered suspicious for malignancy, although most tumors have an even higher level

60. Other tracers Rubidium-82 (Rb-82): Cardiac perfusion Ammonia N-13: Cardiac perfusion F-18 fluciclovine : Prostate cancer recurrence, metastasis Gallium-68 prostate-specific membrane antigen (Ga-68 PMSA): Prostate cancer recurrence Ga-68 DOTATE or DOTATOC: Neuroendocrine/ somatostatinreceptor tumor imaging F-18 sodium fluoride: Bone metastases and tumors

61. ICG

62. VASCULARITY

63. LYMPH NODES

64. Thank you