OSSEOUS PELVIS

Preparatory steps:
- Indications: evaluation or verification of pelvic ring and acetabular fractures, hip dislocation, bone tumours, degenerative, infectious, arthritic and osteonecrotic changes
- Advisable preliminary investigations: always conventional radiography; MRI or ultrasonography may be alternative examinations without exposure to ionising radiation in non- traumatic disorders
- Patient preparation: information about the procedure; restraint from food, but not fluid, is recommended, if intravenous contrast media are to be given
- Scan projection radiograph: frontal from iliac crest to ischial tuberosity
1. DIAGNOSTIC REQUIREMENTS
Image criteria:
1.1 Visualization of
1.1.1 Whole pelvic ring
1.1.2 Hip(s) including the trochanter region
1.1.3 Sacroiliac joints
1.1.4 Pubic symphysis
1.2 Critical reproduction
1.2.1 Visually sharp reproduction of the pelvic bones
1.2.2 Visually sharp reproduction of the hip joint(s)
1.2.3 Visually sharp reproduction of the sacroiliac joints
1.2.4 Visually sharp reproduction of the pubic symphysis
1.2.5 Visually sharp reproduction of the pelvic musculature
2. CRITERIA FOR RADIATION DOSE TO THE PATIENT
2.1 CTDIW : 25 mGy (pilot study (17))
2.1 DLP : 520 mGy cm (pilot study)
3. EXAMPLES OF GOOD IMAGING TECHNIQUE
3.1 Patient position : supine with arms at chest or head level
3.2 Volume of investigation : tumour/fracture: from 1 cm above to 1 cm below the diseased area;
joint disorders: 1 cm above to 1 cm below the joint region
3.3 Nominal slice thickness : 3-5 mm in the hip region; 3-10 mm outside the hip, serial or preferably helical
3.4 Inter-slice distance/pitch : contiguous or pitch = 1.0 in the hip region, <5 mm or a pitch up to 1.2 - 1.5 outside the hip region
3.5 FOV : pelvis, hip or sacroiliac joint dimension (usually 15-40 cm)
3.6 Gantry tilt : usually none, but cranial tilting should be used for examination of the sacroiliac joints to reduce radiation to the female gonads
3.7 X-ray tube voltage (kV) : standard or high kV in large persons to avoid noise
3.8 Tube current and exposure time product (mAs) : should be as low as consistent with required image quality
3.9 Reconstruction algorithm : soft tissue/standard or high resolution
3.10 Window width : 1000-1500 HU (joints/bones)
200-600 HU (soft tissue)
3.11 Window level : 150-200 HU (joints/bones)
30-50 HU (soft tissue)
3.12 Protective Shielding : lead-purse for the male gonads
4. CLINICAL CONDITIONS WITH IMPACT ON GOOD IMAGING PERFORMANCE
4.1 Motion - movement artefact deteriorates image quality and the value of reconstructions
4.2 Intravenous contrast media - useful for delineating malignant and inflammatory lesions extending into the soft tissue, and for detecting traumatic lesion of pelvic organs
4.3 Problems and pitfalls - artefact due to metallic objects such as prothesis
4.4 Modification to technique - intracavitary contrast media to delineate traumatic lesion of pelvic organs