7-A Block R III, Johar Town, Lahore, Pakistan

www.shaukatkhanum.org.pk

SHAUKAT KHANUM MEMORIAL CANCER HOSPITAL & RESEARCH CENTRE

References Conclusion

MATERIALS & METHODS

We analyzed 151 patients injected with 99mTc-MDP for bone scan, 20 patients for stress 99mTc-MIBI, 6 patients for 99mTc-MIBI para-thyroid, 21 patients 99mTc HSA Sentinel, 45 patients Iodine whole-body post therapy. The CT and radiotracer doses were calculated using ICRP conversion factors. The CT portion of SYMBIA T16 system has variable tube current ranges from 20–345 mA.

Shahid Younas1, Syed Haris Ali1, Dr. Khalid Nawaz1, Humayun Bashir Dr1 , Sahar Shahid1, Asma Nisar1, Dr. Maimoona Siddiqui1, Muhammad Bilal2, Ashfaq Zaman2, Madeeha Khalid3,

1- Nuclear Medicine department, Shaukat Khanum Memorial Cancer Hospital and Research Center, Lahore, Pakistan 2- Department of Physics, PIEAS, Islamabad. 3- Department of Physics, The Islamia University of Bahawalpur, Pakistan.

SPECT-CT: HOW MUCH RADIATION DOSE CT CONSTITUTE

CONCLUSION

The risk factor in our case is 0.016% with the addition of diagnostic CT for SPECT/CT. Considering the benefit to the patient in comparison to conventional diagnostic CT the induced radiation doses by SPECT/CT are quite low in our calculations However, effective dose of CT may be balanced further by decreasing the injected nuclear medicine activity at the cost of increased patient scanning time.

RESULTS

The maximum dose for bone patients (% increase with respect to radiotracer) is 1.99 mSv (45.76%) for 99mTc trunk patients and least for head which bears 0.1 mSv (1.79%). The CT dose for abdomen & Pelvis, Chest, Head & neck is 0.78, 0.64, 0.18 mSv respectively. However, chest dose in case 99mTc-MIBI is 3.56 mSv in one phase of the myocardial perfusion imaging. The calculated neck CT dose for 99mTc parathyroid is 0.8 mSv where as it decreased to 0.75 mSv for the 99mTc Sentinel chest patients. The negligible dose rise is observed in case of Iodine-131 post therapy patients with an average CT dose of 1.02 mSv for trunk areas against 1976 mSv dose from radioactive Iodine.

OBJECTIVE:

Effective dose (E) is a single parameter to reflect the relative risk from exposure to ionizing radiation in term of detrimental biologic effects on whole-body exposure. SPECT with multi-slice CT systems has been employed for better attenuation correction and localization. The study was conducted to calculate effective radiation dose both from radiotracer and the CT component of SPECT CT to patients scanned from August, 2014, to August, 2015, on SYMBIA T16 SPECT CT in the department of Nuclear Medicine.

REFERENCES

1. AAPM Task Group Report # 108 2. Pakistan Nuclear Regulatory Authority , PNRA, Regulation: Pak/904: Radiation Protection 3. Dose Record from Pakistan Institute of Nuclear Sciences and Technology (PINSTECH), Islamabad, Pakistan.

Sr. Primary Scan Radiation Induce Dose in SYMBIA T16 SPECT/CT

CT Dose (mSv)

Radiopharmaceutical Dose (mSv)

Accumulative Dose

% increase

1

99mTc-MDP Bone

Chest 0.65 4.95

5.6 13.13

Abdomen & Pelvis 0.87 5.75 16.17

Trunk 10.45 15.4 211.11

Neck 0.29 5.24 5.85

2

99mTc-MIBI Myocardial Perfusion

Chest 3.67 6.96 10.62 52.72

3

99mTc-MIBI Parathyroid

Neck 0.8 7.58 8.37 10.55

4

99mTc-Sentinal

Chest 1.03 -

5

99mTc-Thyriod

Neck 0.01 2.15 2.16 0.46

6 131NaI Post Therapy 0.43 2790 2790.43 0.015