**2. Recent approaches of injectable radiopharmaceuticals as nuclear medicine for imaging and therapy**

The aim of this chapter is to explain about advancements the injectable of biomaterials or radiopharmaceuticals origin used in molecular imaging, therapy and clinical diagnosis. On the basis of intrinsic radiation form, radioisotopes can be divided into following type namely gamma (γ) ray emitters, beta (positron β+ or electron β−) particles emitters and alpha (α) particles emitters or their combinations. In clinical practice and pre-clinical animal studies, mostly used radionuclides are gamma ray emitters like Technetium-99m (99mTc), Iodine-123 (123I) and Galium-67 (67Ga), Positron-emitting radionuclides namely Fluorine-18 (18F), Oxygen-15 (15O), Carbon-11 (11C) and Zirconium 89 (89Zr). Some β-emitters are Rhenium-186/Rhenium-188 (186Re/188Re), Strontium-89 (89Sr), and Yttrium-90 (90Y). Examples of therapeutic α-emitters are Actinium-225 (225Ac), Bismuth-213 (213Bi) and Astatine-211 (211At) [6]. The injected radiopharmaceuticals can be in simple ionic form or in carrier complex form. Carrier complex has better targeting ability for certain tissues and cells and pathways of disease. These are some radioisotopes used for imaging are as follows (**Table 1**):


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**2.2 PET**

*Theranostics: New Era in Nuclear Medicine and Radiopharmaceuticals*

mentioned in **Table 2** which are used in radiation therapy are:

relevance to imaging of radionuclide therapy.

**2.1 SPECT and scintigraphy**

*2.1.1 Current status*

**Table 2.**

*Radiation therapy [12].*

which can be imaged by a γ-camera.

effects and quantification errors.

In case of imaging, the major focus was development of 11C, 18F or 68Ga radiopharmaceuticals to be used in positron emission tomography (PET) and 99mTc-labeled agents for the used in single-photon emission computed tomography (SPECT) [8]. The merits associated with nuclear medicine are many such as it is noninvasive, it gives better in identifying exact region of tumor and beneficial for diagnosis of challenging diseases [9, 10]. In addition to this there is better quantitative analysis which is achieved with a numerous tools available. For example standard uptake values (SUVs) are taken in PET and in case of SPECT it is compared in vivo distribution of the injected materials [11]. There are some common nuclides

**Nuclide Radiation Half-Life Treatment** 32P Β 14.3 d Leukemia therapy 60Co β, γ 5.3 yr External cancer therapy 123I Γ 13.3 yr Thyroid therapy 131Cs Γ 9.7 days Prostate cancer therapy 192Ir β, γ 74 d Coronary disease

This content focuses on the developments in field of imaging technology in

This type of decay of radionuclides determines about the modality for imaging. Planar scintigraphy or SPECT is used for imaging of 177Lu, 90Y, and 131I-which are used for radionuclide therapy. These emit γ-photons (or bremsstrahlung photons),

SPECT/CT systems which are used nowadays are used for both planar and tomographic imaging. Planar imaging is for acquiring whole-body images in when there is limitation of time. SPECT is meant for acquiring 3-dimensional data of structures

Quantitative analysis of SPECT images is determined by converting the acquired

counts in terms of distribution of absorbed dose (in Gy), which is beneficial for planning and dosimetry of therapy involving radionuclide. In clinical practice scatter correction is also implemented and is generally performed employing the tripleenergy window method [13]. Quality of image can be enhanced by using resolution recovery. It is performed by characterizing the shape of the point-spread function accurately, that depends its distance from the camera and there is rotational variation due to the hexagonal pattern of the collimator septa. Reconstruction algorithm

can be incorporated with point-spread function model subsequently [14].

Effects like scatter, blurring and attenuation which degrades image can be corrected to some extent, Although SPECT images can be degraded by partial-volume

18F-FDG PET is used for many PET studies that are in the field of clinical practice and is employed for staging and follow-up post radionuclide therapy.

which would otherwise overlap on each another on planar images.

*DOI: http://dx.doi.org/10.5772/intechopen.91868*

#### **Table 1.**

*Radioisotope imaging [7].*

#### *Theranostics: New Era in Nuclear Medicine and Radiopharmaceuticals DOI: http://dx.doi.org/10.5772/intechopen.91868*

In case of imaging, the major focus was development of 11C, 18F or 68Ga radiopharmaceuticals to be used in positron emission tomography (PET) and 99mTc-labeled agents for the used in single-photon emission computed tomography (SPECT) [8]. The merits associated with nuclear medicine are many such as it is noninvasive, it gives better in identifying exact region of tumor and beneficial for diagnosis of challenging diseases [9, 10]. In addition to this there is better quantitative analysis which is achieved with a numerous tools available. For example standard uptake values (SUVs) are taken in PET and in case of SPECT it is compared in vivo distribution of the injected materials [11]. There are some common nuclides mentioned in **Table 2** which are used in radiation therapy are:


**Table 2.**

*Medical Isotopes*

will be seen.

circulating in lungs [5].

**1.3 Adverse reactions**

sweating, nausea, dry mouth and rashes.

**medicine for imaging and therapy**

isotopes used for imaging are as follows (**Table 1**):

**Organ Isotope used/activity** Brain In-113m/7–10 mCi Kidney Hg-197/150 mCi Lungs Tc-99/1 mCi

Spleen Cr-51/0.3 mCi Bone Sr-85/0.1 mCi

Pancreas Se-75/0.2 mCi Placenta Cr-51/0.05 mCi

I-131/0.15–0.3 mCi In-113/1 mCi

> Sr-87/1 mCi F-18/1 mCi

Tc-99/0.5–1 mCi

ventilation scan. First, one 99mTc-labeled macroaggregated albumin is injected in the peripheral vein, which is then carried to the pulmonary artery system. It does not get absorbed rather it gets distributed evenly in the capillary bed and helps in diagnosis. Where blood flow is good there will be larger number of particles giving out radiation, whereas where there will less perfusion then less particles

In case of ventilation scan, patient is made to inhale radioactive substance such as krypton or 99mTc-labeled DTPA aerosol. Image is obtained where air is seen

The most common adverse reaction associated with radiopharmaceuticals is

**2. Recent approaches of injectable radiopharmaceuticals as nuclear** 

The aim of this chapter is to explain about advancements the injectable of biomaterials or radiopharmaceuticals origin used in molecular imaging, therapy and clinical diagnosis. On the basis of intrinsic radiation form, radioisotopes can be divided into following type namely gamma (γ) ray emitters, beta (positron β+ or electron β−) particles emitters and alpha (α) particles emitters or their combinations. In clinical practice and pre-clinical animal studies, mostly used radionuclides are gamma ray emitters like Technetium-99m (99mTc), Iodine-123 (123I) and Galium-67 (67Ga), Positron-emitting radionuclides namely Fluorine-18 (18F), Oxygen-15 (15O), Carbon-11 (11C) and Zirconium 89 (89Zr). Some β-emitters are Rhenium-186/Rhenium-188 (186Re/188Re), Strontium-89 (89Sr), and Yttrium-90 (90Y). Examples of therapeutic α-emitters are Actinium-225 (225Ac), Bismuth-213 (213Bi) and Astatine-211 (211At) [6]. The injected radiopharmaceuticals can be in simple ionic form or in carrier complex form. Carrier complex has better targeting ability for certain tissues and cells and pathways of disease. These are some radio-

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**Table 1.**

*Radioisotope imaging [7].*

*Radiation therapy [12].*

This content focuses on the developments in field of imaging technology in relevance to imaging of radionuclide therapy.
