Rx Act Nasal Original

2.1       Radiation Safety - Drug Handling

Choline C 11 Injection is a radioactive drug and should be handled with appropriate safety measures to minimize radiation exposure during administration. Use waterproof gloves and effective shielding when handling Choline C 11 Injection. Radiopharmaceuticals, including Choline C 11 Injection, should only be used by or under the control of physicians who are qualified by specific training and experience in the safe use and handling of radioactive materials, and whose experience and training have been approved by the appropriate governmental agency authorized to license the use of radionuclides.

2.2       Recommended Dose and Administration Instructions

The recommended dose is 370 – 740 MBq (10 – 20 mCi) administered as a bolus intravenous injection. The radioactivity dose (370 – 740 MBq, 10 – 20 mCi) is chosen based on patient body dimensions and the characteristics of the image acquisition system  

Inspect Choline C 11 Injection visually for particulate matter and discoloration before administration. Do not use the drug if the solution contains particulate matter or is discolored. 
Aseptically withdraw Choline C 11 Injection from its container and administer the drug as a bolus through a peripheral venous catheter. 
Dispose of any unused drug in a safe manner, in compliance with applicable regulations.  2.3       Patient Preparation

Prior to administration of Choline C 11 Injection:

Fasting for at least six hours is recommended to minimize the potential for dietary choline interference with radioactivity uptake in tissue.
Ensure that the patient is well hydrated and encourage voiding when imaging is completed.    2.4       Radiation Dosimetry

The estimated radiation absorbed doses for adults from intravenous injection of Choline C 11 Injection are shown in Table 1.  These estimates are calculated from data in Tolvanen 1and using OLINDA/EXM (Organ Level Internal Dose Assessment/Exponential Modeling) software from Vanderbilt University.2

Table 1: Estimated Radiation Absorbed Dose Per Unit Activity for Adults, Choline C 11 Injection  Organ/Tissue  Mean Absorbed Dose Per Unit Administered Activity (μGy/MBq)b  Adrenals  3.59  Bone – Osteogenic Cells   4.81  Bone – Red Marrow  1.90  Brain  1.16  Breast  1.39  Gallbladder Wall  4.54  GIa – Lower Large Intestine Wall   1.81  GIa – Small Intestine  2.35  GIa – Stomach Wall  6.00  GIa – Upper Large Intestine Wall   6.41  Heart wall  3.43  Kidneys  20.62  Liver  20.11  Lungs  4.59  Muscle  2.54  Ovaries  2.02  Pancreas  29.19  Skin  1.22  Spleen  9.16  Testes  1.36  Thymus  1.69  Thyroid  1.49  Urinary Bladder Wall  3.41  Uterus  1.96  Total body  2.97  Effective Dose (μSv/MBq)c  4.35

a Gastrointestinal
b Assumed radiation weighting factor, wr, (formerly defined as quality factor, Q) of 1 for conversion of absorbed dose (Gray or rad) to dose equivalent (Sieverts or rem) for C 11. To obtain radiation absorbed dose in rad/mCi from the above table, multiply the dose in μGy/MBq by 0.0037, (e.g., 3.59 μGy/MBq × 0.0037 = 0.0133 rad/mCi).
c Radiation tissue weighting factors, wT, used in the calculation of effective dose are from 1990 Recommendations of the International Commission on Radiological Protection, ICRP Publication 60 (1991). To obtain radiation absorbed dose in rem/mCi from above table, multiply the dose in μGy/MBq by 0.0037, (e.g., 4.35 μGy/MBq × 0.0037 = 0.0161 rem/mCi).

The effective dose resulting from a 740 MBq (20 mCi) dosage of Choline C 11 Injection is 3.22 mSv in an adult, (740 × 4.35 = 3219 μSv = 3.2 mSv). The use of a CT scan to calculate attenuation correction for reconstruction of 11C-choline images (as done in PET/CT imaging) will add radiation exposure. Based upon current scanning techniques, an effective dose of 5.8 mSv would be added from CT scanning. The actual radiation dose is operator, scanner, and patient dependent. The total radiation exposure from 11C-choline administration and subsequent scan on a PET/CT scanner is estimated to be 9.0 mSv (3.2 mSv + 5.8 mSv).

2.5       Imaging Guidelines Initiate image acquisition immediately after administration of Choline C 11 Injection.  Imaging is typically performed from the base of the pelvis to the base of the skull.
Acquire static emission images 0 – 15 minutes from the time of injection.
Localized uptake of 11C-choline in a site suspicious for prostate cancer recurrence (a positive image) is determined by comparison of the anatomical relationship of concentrated radioactivity to the neighboring tissue background, exclusive of the radioactivity physiologically accumulated within the pancreas, liver, spleen, kidney and colon.