Medical Imaging

Introduction

Medical imaging is done on walk-in basis, but with prior appointment from the referral clinic (eg ORL Clinic), and requires overnight patient fasting. A minimum 5 hours fasting is required if a patient has eaten or taken breakfast and was unaware of the prerequisite fasting prior to scanning or imaging. Imaging requires that the patient change into a hospital gown without any metal parts (no bras, no hooks etc) before commencing scanning/imaging. A butterfly needle is inserted in the left hand for administration of media. Media are injected for baseline. Another media is injected to overcome hypersensitivity (if any - eg allergic reactions to certain foods/alahan kepada makanan such as sefood (prawns), sinus/resdung, other). Scanning is performed once the basic media and hypoallergens are injected. Iodinated contrast media are then injected for image contrast after the basic scan is performed.

MRI versus CT Scan

For MRI, the time taken to do a whole body scan is approximately 20 minutes. For CT Scan, it takes less than 20 minutes. CT Scan of 2 legs below knee for an adult male on wheelchair takes 5 minutes; no change of clothes is required if the patient is wearing a singlet and kain pelekat. CT Scan from vertex to upper abdomen takes 13 minutes in total for a 57-year old woman, from changing clothes, positioning the torso and head, adjusting head under the red beam, water calibration for baseline, first scanning, injecting contrast media, re-scanning, and change of clothes and removing the butterfly port. MRI uses powerful magnets and there is no x-ray radiation involved. MRI is considered relatively safe. CT Scan involves high dose x-ray radiation (similar to sudden exposure to x-ray radiation coming from an atomic bomb). CT Scan is relatively unsafe compared to MRI, but is mostly performed today compared to MRI, which is time-consuming.

When to install a butterfly port and when to remove it?
The butterfly port can be installed after registration at CT Scan counter and be left intact for 5 hours. The patient returns and CT Scan begins with changing into the blue hospital gown. The tie strings are criss-crossed and tied in front. After scanning, it is better to change into normal clothes first and then remove the butterfly port. Strong pressure must be applied on the insertion site when the butterfly port is removed as blood will start to gush out. If the patient requests to remove the butterfly port first before changing clothes, it is better to advise the patient on this blood matter. Even if the patient has the butterfly port removed, it will bleed and the patient will forget this while changing and walking around until a considerable amount of blood fills the cotton swab and surgical tape and feels blood gushing out. Apply a little bit more pressure on the sampling site will stop bleeding. Of course, there are dried blood marks that will need to be washed.

Muslim patients

For Muslim patients, it is advisable to have CT Scan done early in the morning after overnight fasting. For patients who have eaten on the day of CT Scanning, an additional 5 hours fasting is required (eg 7.30 am - 12.30 pm). This means if a patient ate breakfast at 7.30 am and came for CT Scan that morning, he has to wait till past 12.30 pm, even up to 1 pm before a CT Scan can be done. CT Scan takes less than 20 minutes at most if a significant amount of adjusting needs to be done before CT Scan can commence. By the time a patient completes the CT Scan, it is almost time for Azan Zohor and Solat Zohor. Blood marks must be carefully washed before ablution (Wudhu') can be performed by the patient if he want to follow the congregational prayer or perform it solo.

Number of CT Scan Patients

Hospital USM (HUSM) at Kubang Kerian in Kelantan, Malaysia, has 17 patients daily on appointment basis as ordered by referring clinicians. However, up to 20 or more patients may be referred to the CT Scan unit. Most are bed-ridden and some are on wheelchairs.

CT Scan Facilities

There is only one Siemens SOMATOM Definition AS CT Scanner at HUSM. I feel there should be another one.

The staff rotate daily between the main Radiology Unit and the CT Scan unit. Four to 5 staff attend to a patient for CT scanning. One staff I asked, has worked for 15 years at the CT Scan unit.

The present CT Scan room has quite narrow doors, just wide enough for modern hospital beds to be wheeled in; they should make them wider in modern hospitals. There were severe scratch marks on the prep room wall, indicating how narrow the passage from the entrance door to the scanning room is.

Abbreviations

CT: computed tomography --> the machines are named SOMATOM
MRI: magnetic resonance imaging --> the machines are named MAGNETOM
MDCT: multi detector computed tomography
DECT: dual energy CT
VA: virtual autopsy
U/S: ultrasound

MCBI: megavoltage cone beam imaging
MAGAT: methacrylic acid, gelatin, and tetrakis
MAGIC: methacrylic acid, gelatin, copper sulphate, ascorbic acid, hydroquinone, and water
MAGAS: methacrylic acid, gelatine, and ascorbic acid
PAGAT: polyacrylamide, gelatin, and tetrakis
PAGAS: polyacrylamide and ascorbic acid

BANG: bisacrylamide, nitrogen, gelatin

MC: Monte Carlo simulation
NIPAM: N-isopropylacrylamide
HU: Hounsfield unit
LAC: linear attenuation coefficient
CTDI: CT dose index

Case studies & write-ups

1. Clinical specials/specialties
2. Anatomic region
3. Systems
4. Clinical software (s/w) applications (apps) and benefits
5. S/w version
6. Technologies & innovations, and gantry electronics (insulated with extra silicon)
7. Recommended protocol

Imaging priorities

1. First line imaging: x-ray, U/S, CT
2. Second line procedure: MRI

Applications of clinical imaging

1. Oncology
2. Neurology
3. Cardiology
4. Acute Care
5. Forensic Pathology (uses MDCT & MRI)

DECT

1. DECT is Dual Energy CT
2. It has 2 x-ray sources running simultaneously at different energy levels (80 kV & 140 kV)
3. Can obtain additional information about the elementary chemical composition (C, H, O, N, P, Cl) of the scanned material (gelatin, Tetrakis, methacrylic, water)
4. Assign colours according to the value differences between 80 kV and 140 kV, to obtain colour-mapped dual energy image
5. Can differentiate between calcifications and iodine contrast for stenosis, soft plaques, etc
6. Can use this technique for direct subtraction of bone from the CT raw data; MC code; reconstruction algorithm
7. No need to do post processing
8. Better visualize blood clots in vessels, bleeding in soft tissues
9. Do classification of different tissue types --> identify tendons and cartilage

Hospital scanner

1. Siemens SOMATOM Definition AS CT scanner
2. Siemens Primus linear accelerator (linac)

Siemens CT Scanners: SOMATOM at rear and Primus in foreground

Introductory topics

1. Diffusion problem
2. Single spin echo
3. Multiple spin echo
4. Basic principles of FT-Raman
5. DICOM
6. CERN
7. LAC

Research topics

1. CT based MAGAT gel dosimetry system
2. 3D dose verification in radiotherapy
3. Personalized radiation therapy

External links:
http://en.wikipedia.org/wiki/Medical_imaging
https://en.wikipedia.org/wiki/Magnetic_resonance_imaging
http://en.wikipedia.org/wiki/Computed_Tomography
https://en.wikipedia.org/wiki/CT_scan
http://medicalphysicsweb.org/cws/channel/research
http://www.micropos.se/

Google search for Siemens SOMATOM Definition AS:
https://www.google.com/?gws_rd=ssl#q=Siemens+SOMATOM+Definition+AS