All the contents are provided by Computer Tomography team of the Diagnostic Radiology and Organ Imaging Department, PWH

Copyright © 2002-2008.
Dept. of Diagnostic Radiogy and Organ Imaging, CUHK

CT suite in P.W.H. operates on a 24 hours basis. Daily rountine booking cases for Inpatient and Outpatient start from 8:00 a.m. to 5:30 p.m. Urgent CT services running continuously.

•Normally, patients need to fast 4 hours  before examination.

•If patient has allergic history, he/she should approach the referring doctor to obtain steroids.

•For all CT abdomen and/or pelvis, please obtain oral contrast from Rm. 21 within 7 days before the examination.

•CT abdomen and pelvis deliver certain amount of radiation dose to the abdomen and pelvis. It is advised that female patients of reproductive age should have the examination done within menstrual cycle, in order to prevent the irradiation of the fetus from unknown pregnancy. If your appointment does not fit into the first 10 days, you may change your appointment by calling 2632 3200.

•For children from 0-3 years old, patient should contact pediatric specialist clinic to arrange for admission before the examination.

If you have the following allergic history, you should have steroid pre-medication before CT scan.

Any drug allergy
Seafood allergy
Other specify allergy
Asthma
Atopia (e.g. hay fever)
Urticaria or eczema
Previous contrast reaction

*If in doubt, please consult Radiology Department*

A. Oral contrast (2% Conray 30)

    For drinking only, the purpose is for well delineation of GI tract, so that it would be easier to differentiate abdominal and pelvis features.

B. Intravascular contrast - 3 different strengths used for different examination regions.

    Omnipaque 240
    Omnipaque 300
    Visipaque 270

Child-bearing age
According to HA guideline in 1999 concerning about “X-Ray investigation of women of child-bearing age”.

When a female of child-bearing age presents for an x-ray examination involving direct irradiation of the abdomen or pelvis, she should be asked whether she is or might be pregnant. If the patient cannot exclude the possibility of pregnancy, she should be asked whether her menstrual period is overdue. If it is overdue consideration is given to postponing the examination - the “28-day rule”.
If the possibility of pregnancy is excluded, proceed with the x-ray examination.
If pregnancy cannot be excluded but the period is not overdue proceed with the x-ray examination except for high dose procedures (i.e. abdominal CT, pelvis CT, barium enema and any other special x-ray exams likely to deliver a dose of tens of milligray such as abdominal CT to the conceptus). in which case the examination may be postponed to the early part of the menstrual cycle - the “limited return to the 10-day rule”. Exception would include urgent x-ray examinations when benefits are likely to far outweigh any small risk from the irradiation.

Complication
Complication of venipuncture:
Bruising
Fainting
Extravasation
Nerve damage

Reaction to contrast medium injection

Mild Sneezing Nausea Single emesis Vertigo Moderate Prurities < 12 hives Flush/erythema Fever/chills Increase or decrease BPPalpitations Severe Dyspnea Laryngeal edema Periorbital edema Bronchospasm Cardiac arrhythmia Angina Pulmonary edema

After examination, please follow up with your referring clinician/specialty for the examination result according to your next appointment.

According to “The Radiographer - Vol.40”
Comparison to conventional X-ray procedures
There is often a misconception that because the volume of tissue irradiated in a single slice is small, the total patient dose is also small. In practice, CT examinations may comprise many slices exposing a much larger volume of tissue than a single slice. The table shows that, in many cases, CT scans give considerably higher doses to the patient than comparable conventional X-ray procedures.

Typical levels of mean effective dose equivalent from CT and Conventional X-ray procedures

Examination CT (mSv) Conventional (mSv) Head Cervical Spine Thoracic Spine Chest Abdomen Lumbar Spine Pelvis IVP Barium Meal Barium Enema 3.5 1.9 7.8 9.1 8.8 6.0 9.4 - - - 0.2 - 0.9 0.05 1.4 2.2 1.2 4.4 3.8 7.7