Teleradiology...an introduction!

Teleradiology : An Introduction

                                                                                                - Ganesh Bdr. Thapa BScMIT 3rd Batch

                                                                                                     - Deelip Saud BScMIT 5th Batch

I. INTRODUCTION AND DEFINITION

Teleradiology is the electronic transmission of radiologic images from one location to another for the purposes of interpretation and/or consultation. Teleradiology may allow more timely interpretation of radiologic images and give greater access to secondary consultations and to improved continuing education. Users in different locations may simultaneously view images. Appropriately utilized, teleradiology may improve access to radiologic interpretations and thus significantly improve patient care. Teleradiology is not appropriate if the available teleradiology system does not provide images of sufficient quality to perform the indicated task. When a teleradiology system is used to render the official interpretation, there should not be a clinically significant loss of data from image acquisition through transmission to final image display. For transmission of images for display use only, the image quality should be sufficient to satisfy the needs of the clinical circumstance. This standard defines goals, qualifications of personnel, equipment guidelines, licensing, credentialing, liability, communication, quality control, and quality improvement for teleradiology. While not all-inclusive, the standard should serve as a model for all physicians and health care workers who utilize teleradiology.

II. GOALS

Teleradiology is an evolving technology. New goals will continue to emerge. The current goals of teleradiology include:

A. Providing consultative and interpretative radiologic services.

B. Making radiologic consultations available in medical facilities without on-site radiologic support.

C. Providing timely availability of radiologic images and image interpretation in emergent and nonemergent clinical care areas.

D. Facilitating radiologic interpretations in on-call situations.

E. Providing subspecialty radiologic support as needed.

F. Enhancing educational opportunities for practicing radiologists.

G. Promoting efficiency and quality improvement.

H. Providing interpreted images to referring providers.

I. Supporting telemedicine.

J. Providing supervision of off-site imaging studies.

III. QUALIFICATIONS OF PERSONNEL

The radiologic examination at the transmitting site must be performed by qualified personnel trained in the examination to be performed. In all cases this means a licensed and/or registered radiologic technologist, radiation therapist, nuclear medicine technologist, or sonographer. This technologist must be under the supervision of a qualified licensed physician. It is desirable to have a Qualified Medical Physicist and/or image management specialist on site or as consultants.

A. Physician

The official interpretation of images must be done by a physician.

B. Radiologic Technologist, Radiation Therapist, Nuclear Medicine Technologist, or Sonographer

The technologist, therapist, or sonographer should be:

   1. Certified by the appropriate registry

   2. Trained to properly operate and supervise the teleradiology system.

C. Qualified Medical Physicist

D. Image Management Specialist

IV. EQUIPMENT SPECIFICATIONS

Specifications for equipment used in teleradiology will vary depending on the individual facility’s needs but in all cases should provide image quality and availability appropriate to the clinical need. Digital Imaging and Communication in Medicine (DICOM) Standard is strongly recommended for all new equipment acquisitions, and consideration of periodic upgrades incorporating the expanding features of that standard should be part of the continuing quality-improvement program. Equipment guidelines cover two basic categories of teleradiology when used for rendering the official interpretation: small matrix size (e.g., computed tomography [CT], magnetic resonance imaging [MRI], ultrasound, nuclear medicine, digital fluorography, and digital angiography) and large matrix size (e.g. digital radiography and digitized radiographic films). Small matrix: The data set should provide a minimum of 512 x512 matrix size at a minimum 8-bit pixel depth for processing or manipulation with no loss of matrix size or bit depth at display.

CR STANDARDS Teleradiology

General Diagnostic Radiology

Large matrix: The data set should allow a minimum of 2.5 lp/mm spatial resolution at a minimum 10-bit pixel depth.

A. Acquisition or Digitization

1. Direct image capture

The entire image data set produced by the digital modality both in terms of image matrix size and pixel bit depth should be transferred to the teleradiology system. It is recommended that the DICOM standard be used.

2. Secondary image capture

a. Small matrix images. Each individual image should be digitized to a matrix size as large or larger than that of the original image by the imaging modality. The images should be digitized to a minimum of 8 bits pixel depth. Film digitization or video frame grab systems conforming to the above specifications are acceptable.

b. Large matrix images. These images should be digitized to a matrix size corresponding to 2.5 lp/mm or greater, measured in the original detector plane. These images should be digitized to a minimum of 10 bits pixel depth.

3. General requirements

At the time of acquisition (small or large matrix), the system must include: Annotation capabilities including patient name, identification number, date and time of examination, name of facility or institution of acquisition, type of examination, patient or anatomic part orientation (e.g., right, left, superior, inferior), and amount and method of data compression. The capability to record a brief patient history is desirable.

B. Compression

Data compression may be used to increase transmission speed and reduce storage requirements. Several methods, including both reversible and irreversible techniques, may be used, under the direction of a qualified physician, with no reduction in clinically significant diagnostic image quality. The types and ratios of compression used for different imaging studies transmitted and  stored by the system should be selected and periodically reviewed by the responsible physician to ensure appropriate clinical image quality.

C. Transmission

The type and specifications of the transmission devices used will be dictated by the environment of the studies to be transmitted. In all cases, for official interpretation, the digital data received at the receiving end of any transmission must have no loss of clinically significant information. The transmission system shall have adequate error-checking capability.

D. Display Capabilities

Display workstations used for official interpretation and employed for small matrix and large matrix systems should provide the following characteristics:

1. Luminance of the gray-scale monitors should be at least 50 foot-lamberts.

2. Lighting in the reading room should be controlled to eliminate reflections in the monitor and to lower the ambient lighting level as much as is feasible.

3. Capability for selecting image sequence.

4. Capability of accurately associating the patient and study demographic characterizations with the study images.

5. Capability of window and level adjustment, if those data are available.

6. Capability of pan and zoom functions.

7.Capability of rotating or flipping the images provided correct labeling of patient orientation is preserved.

8. Capability of calculating and displaying accurate linear measurements and pixel value determinations in appropriate values for the modality (e.g., Hounsfield units for CT images), if those data are available.

9. Capability of displaying prior image compression ratio, processing, or cropping.

10. Should have the following elements of display available:

a. Matrix size.                                                                                   

b. Bit depth.

c. Total number of images acquired in the study.

d. Clinically relevant technical parameters. When the display systems are not used for the official interpretation, they need not meet all the characteristics listed above.

E. Archiving and Retrieval If electronic archiving is to be employed, the guidelines listed

below should be followed:

1. Teleradiology systems should provide storage capacity sufficient to comply with all facility, state, and federal regulations regarding medical record retention. Images stored at either site should meet the jurisdictional requirements of the transmitting site. Images interpreted

off-site need not be stored at the receiving facility, provided they are stored at the transmitting site.

However, if the images are retained at the receiving site, the retention period of that jurisdiction must be met as well. The policy on record retention must be in writing.

2. Each examination data file must have an accurate corresponding patient and examination database record, which includes patient name, identification number, examination date, type of examination, and facility at which examination was performed. It is desirable that space be available for a brief clinical history.

3. Prior examinations should be retrievable from archives in a time frame appropriate to the clinical needs of the facility and medical staff.

4. Each facility should have policies and procedures for archiving and storage of digital image data equivalent to the policies for protection of hard-copy storage media to preserve imaging records.

F. Security

Teleradiology systems should provide network and software security protocols to protect the confidentiality of patients’ identification and imaging data consistent with federal and state

legal requirements. There should be measures to safeguard the data and to ensure data integrity against intentional or unintentional corruption of the data.

G. Reliability and Redundancy

Quality patient care may depend on timely availability of the image interpretation. Written policies and procedures should be in place to ensure continuity of teleradiology services at a level consistent with those for hard-copy imaging studies and medical records within a facility or institution. This should include internal redundancy systems, backup telecommunication links, and a disaster plan.

V. LICENSING, CREDENTIALING, AND LIABILITY

Physicians who provide the official interpretation of images transmitted by teleradiology should maintain licensure as may be required for provision of radiologic service at both the transmitting and receiving sites. When providing the official interpretation of images from a hospital, the physician should be credentialed and obtain appropriate privileges at that institution. These physicians should consult with their professional liability carrier to ensure coverage in both the sending and receiving sites (state or jurisdiction). The physician performing the official interpretations is responsible for the quality of the images being reviewed. Images stored at either site should meet the jurisdictional requirements of the transmitting site. Images interpreted off-site need not be stored at the receiving facility, provided they are stored at the transmitting site. However, if images are retained at the receiving site, the retention period of that jurisdiction must be met as well. The policy on record retention should be in writing. The physicians who are involved in practicing teleradiology will conduct their practice in a manner consistent with the bylaws, rules, and regulations for patient care at the transmitting site.

VI. DOCUMENTATION

Communication is a critical component of teleradiology. Physicians interpreting teleradiology examinations should render reports in accordance with the best Standard for Communication: Diagnostic Radiology.

VII. QUALITY CONTROL AND IMPROVEMENT, SAFETY, INFECTION CONTROL, AND PATIENT EDUCATION CONCERNS

policies and procedures related to quality, patient education, infection control, and safety should be developed and implemented on Quality Control and Improvement, Safety, Infection Control, and Patient Education Concerns appearing elsewhere. Any facility using a teleradiology system must have documented policies and procedures for monitoring and evaluating the effective management, safety, and proper performance of acquisition, digitization, compression, transmission, archiving, and retrieval functions of the system. The quality-control program should be designed to maximize the quality and accessibility of diagnostic information. A test image, such as the SMPTE test pattern, should be captured, transmitted, archived, retrieved, and displayed at appropriate intervals, but at least monthly, to test the overall operation of the system under conditions that simulate the normal operation of the system. As a spatial resolution test, at least 512 x 512 resolution should be confirmed for small-matrix official interpretation, and 2.5 lp/mm resolutions for large-matrix official interpretation. As a test of the display, SMPTE pattern data files sized to occupy the full area used to display images on the monitor should be displayed. The overall SMPTE image appearance should be inspected to assure the absence of gross artifacts (e.g., blurring or bleeding of bright display areas into dark areas or aliasing of spatial resolution patterns). Display monitors used for primary interpretation should be tested at least monthly. As a dynamic range test, both the 5% and the 95% areas should be seen as distinct from the respective adjacent 0% and 100% areas.

2 The Rules of Ethics state: “it is proper for a diagnostic radiologist to provide a consultative opinion on radiographs and other images regardless of their origin. A diagnostic radiologist should regularly interpret radiographs and other images only when the radiologist reasonably participates in the quality of medical imaging, utilization review, and matters of policy which affect the quality of patient care.”

Nepal and Teleradiology

Nepal has a large rural population and the number of radiologists is very less. So the importance of Teleradiology is more in Nepal.

Where to find more:

The essential physics of medical imaging

www.acr.org

www.books.google.com

how reader acquires the medical image?

This shows how image is acquired from the CR imaging PSP after getting a patient x-rayed!

CT Colonography ...

                             

CT Colonography (Virtual Colonoscopy)

Niranjan Thapa, Radiology Technologist

Introduction:

CT colonography is a relatively new technique that is becoming increasingly popular. The technical aspects, indications, advantages and diagnostic performance of this technique are briefly reviewed. Until recent years, only conventional colonoscopy and double-contrast barium enema have been used for evaluation of the whole colon. Conventional colonoscopy is considered to be highly sensitive and specific for the detection of colonic neoplasia, but it is not perfect and some lesions may be missed. In addition, conventional colonoscopy may be associated with serious complications when used as a screening tool in an average-risk population, limiting its acceptance as a broad based screening test. The aim of colonoscopy is to completely evaluate the colon and to reach the cecum, but this is not always possible. Even experienced colonoscopists may be unable to complete the colonoscopy due to multiple reasons such as severe diverticulosis, stricture, obstructing mass, or fixation of colonic loops due to adhesions after surgery. In addition, performing colonoscopy requires discontinuation of oral anticoagulation treatment that may not be advisable to some patients. The need for sedation coupled with substantial costs associated with conventional colonoscopy may make this method of screening less attractive in the large average-risk population above the age of 50. Recent studies show that double contrast barium enema has a poor sensitivity with detection rates as low as 48% for polyps and adenomas larger than 1.0 cm and may be associated with considerable patient discomfort. In addition, since this technique is used much less frequently, there is a significant decrease in the level of expertise of radiologists performing the examination, further lowering its accuracy. With acceptable screening techniques only 20–30% of all individuals at risk have undergone any form of colorectal screening.

CT colonography (CTC), also known as virtual colonoscopy, is a technique that uses data generated from CT imaging of the fully prepared and gas-distended colon to generate two-dimensional (2D) and three-dimensional (3D) images of the colon. It was first reported by Vining and Gelfand in 1994 as a rapid, noninvasive imaging method to investigate the colon and rectum. With the advent of multi-detector CT and CT software, volumetric data of the entire colon are acquired in a few seconds of CT scanning with a total of 10–20 min of examination time. Assessment of the colon requires assessment of the 2D (axial and coronal planes) and 3D images which also includes endoluminal navigation of the colon. Since the advent of CTC, it has been regarded as a potential alternative technique to conventional colonoscopy for the detection of colorectal polyps and cancers.

Indications:

·         Failed or Incomplete Colonoscopy

CTC can be performed following incomplete colonoscopy that occurs in 5–15% of studies due to obstructing colorectal lesions or technical reasons such as a long and tortuous colon, or patient’s discomfort. CTC has the ability to complete the colon evaluation as well as identify the cause of endoscopic failure in a large percentage of cases.

·         Contraindication to Endoscopic Colonoscopy

Some patients that require colonoscopy cannot have the procedure due to various reasons such as: severe comorbid disease, advanced age, bleeding disorders, very tortuous colon, prior allergic reaction to sedation, etc these patients may benefit from CTC.

·         Patients’ Refusal to Colonoscopy

Some patients that require colonoscopy refuse to have the procedure due to lack of information or fear and may agree to have CTC.

·         Extrinsic Compression of the Colon on Colonoscopy

A patient that underwent a complete colonoscopy that demonstrated suspected extrinsic compression on the colon may undergo CTC. The reason for the extrinsic compression (adjacent spleen, liver impression or distended bowel loops) may be demonstrated on the 2D images.

·         Screening for Colorectal Cancer

Although CTC is a promising technique, it has not yet been approved for colorectal screening in large-scale populations. In the near future, it may provide a rapid safe and effective screening test to screen the colon for neoplasia.

Contraindications:

·         Symptomatic acute colitis, acute diverticulitis

·         Recent colorectal surgery, Recent deep endoscopic biopsy or polypectomy/mucosectomy

·         Known or suspected colonic perforation,

·         Routine follow-up of inflammatory bowel disease

Patient Preparations:

Thorough bowel preparation is mandatory for an accurate CTC examination, since residual stool and large amounts of residual fluid may obscure small polyps and adherent stool may mimic a polyp or mass. Contrary to endoscopic colonoscopy, residual feces and fluid cannot be aspirated. A well-prepared, well-distended colon reduces interpretation time as well as false-positive findings. Patients undergo bowel preparation for 24–48 h prior to the procedure using various products available on the market consisting of either a common barium enema preparation (magnesium citrate, bisacodyl tablets, cleansing enemas or suppositories) or a balanced polyethylene glycol solution.

A phospho-soda preparation is more commonly used since it is reported to result in significantly less residual fluid than a polyethylene glycol electrolyte solution preparation and is therefore less likely to obscure small polyps. The use of spasmolytic agents such as glucagon to prevent collapse and spasm of the colon is controversial and usually avoided since it has been reported by some authors to have no beneficial effect and may also lead to unwanted reflux of air into the ileum through the ileocecal valve.

Fecal and fluid tagging is a promising technique that is becoming more popular. It may be performed with or without electronic bowel cleansing. The patient ingests small amounts of barium or iodinated oral contrast with meals prior to CTC. The high attenuation contrast incorporates within the residual stool facilitating differentiation from polyps. When electronic bowel cleansing techniques are used (‘digital cleansing’), a prep-less CTC examination may be performed. The high-attenuation tagged stool is segmented from the data leaving only the colonic mucosa and filling defects attributed to polyp and cancerous masses. Barium suspension given six to seven times over the course of 48 h prior to CTC has been reported to tag 80–100% of the stool and demonstrated good results for polyp detection without bowel cleansing. In a recent study, the sensitivity and specificity of fecal-tagged CTC for the detection of colorectal polyps 10 mm and larger was reported to be 100%. However, fecal tagging may sometimes obscure colorectal lesions, especially if large amounts of fecal residue are present and no electronic cleansing techniques are available.

It is clear that there is tremendous potential for using CTC as a screening study if limited bowel preparation is used, reducing patient discomfort associated with traditional cleansing techniques and resulting in an improved perception of the screening study. However, currently, fecal tagging is used as an addition to the standard preparation and prep-less CTC is not commercially performed.

 Examination Technique

Patients are placed in the right lateral decubitus position on the CT table, a small catheter is inserted into the rectum and using a plastic bulb connected to the rectal catheter, room air, or CO 2, is gently insufflated into the colon. The amount of air or CO2 that is insufflated is determined by patient tolerance, or by pressure-sensitive insufflators monitors that stop the insufflations once threshold pressure has been achieved. Although many centers use room air since colonic distension is easily and reliably achieved with atmospheric air, carbon dioxide is becoming increasingly popular and is considered to be more comfortable, due to the more rapid absorption of CO2 through the colon wall and blood causing less cramping after the procedure.

Adequate distension is crucial for accurate assessment of the colon as polyps may be obscured in collapsed bowel segments. After the colon is insufflated, a CT scout image is obtained in the supine position to assess the degree of colonic distension. The patient is scanned in the supine position and then turned onto the prone position. A CT scout image is again obtained to assure that colonic distension is still adequate and the study is then completed. Dual positioning has been shown to improve colonic distension allowing confirmation of suspected findings and to increase detection of colonic polyps 6 5 mm by approximately 15% compared with supine positioning alone.

 Technical Aspects

CTC can be performed using a single or multi-detector CT scanner with the acquisition of volumetric data from the entire colon. The new multi-detector CT scanners allow 4–64 sections to be obtained in a single rotation of the X-ray tube enabling fast scanning, and shorter acquisition time, resulting in less motion artifacts due to breathing and bowel peristalsis and significantly improved demonstration of the colon compared with single- detector row CT. Using the multi-detector scanners, the colon is usually scanned using a section thickness of 1–2 mm compared to 5 mm or more using single-detector CT scanners. Thinner scanning results in near isotropic data (data with equal resolution in all imaging planes), allowing excellent coronal, sagittal and endoluminal images. No significant differences in the detection of polyps larger than 10 mm has been demonstrated between single- and multi-detector row CT.

However, evaluation of thinner slices improves diagnostic performance. Thicker slices were found to be inadequate for the evaluation of small polyps. Intravenous contrast is not routinely used, although it has been shown to significantly improve readers’ confidence, colonic wall conspicuity, and depiction of sub centimeter colorectal polyps. However, the added value of administration of intravenous contrast material in colonic depiction has been modest. Intravenous administration of contrast material may rarely be associated with serious allergic reactions, but minor reactions are not uncommon (3–4% of patients).

In addition, there is an associated increase in cost and substantial increase in examination time. Intravenous contrast is therefore mostly used for problem solving in selected groups of patients, including those who have sub-optimally prepped colon seen during initial scanning in the supine position. It is also used in patients who have colonic masses, for assessment of peri-colonic spread, lymphadenopathy and distant metastases.

 Radiation Risk

The lifetime risk of developing fatal cancer as a result of ionizing radiation exposure is estimated by the International Commission on Radiological Protection, or ICRP, to be approximately 5% per Sievert. Because of the long latency period, radiation-induced cancer death becomes less probable the older the radiated person is. The targeted population for CTC is 50 years of age and older. The ICRP data indicate that the probability of inducing fatal cancer in this age group is approximately 2.5% per Sievert, and at the age of 70, the risk is half this value. The effective dose of CTC is estimated at about 8.8 mSv (range 4–12 mSv) and carries a risk of 0.02% in a 50-year-old individual and is lower for older patients. In order to minimize the dose, efforts have been made to adapt the tube current to the minimum accepted dose while not diminishing study performance. No change was reported in the diagnostic efficacy when lowering the tube current from 140 to 70 mA using single-detector CT and multidetector CT. Low-dose CTC was shown to have excellent sensitivity and specificity for detection of colorectal neoplasm’s 10 mm and larger.

The performance of CTC using an ultra-low radiation dose of 10 mAs has been shown to compare favorably with conventional colonoscopy in the detection of polyps larger than 6 mm with markedly decreased performance for small polyps of 5 mm or smaller. The reduction in tube current has been shown to result in more noise with degradation of image quality. However, it has recently been shown that combined x-, y- and z-axis tube current modulation leads to significant reduction of radiation exposure without loss of image quality.

Interpretation of CTC Examinations

Acquired CT data are transferred onto a dedicated post processing workstation, equipped with navigator software, permitting the radiologist to obtain Multiplanar reformations (MPR, 2D), as well as to construct an endoluminal model of the air-distended colon (3D model). The endoluminal model allows fly through capabilities in the distended colon enabling viewing of the distended colonic lumen, in both the antegrade and retrograde directions. Some navigator software also allows ‘virtual dissection’, or ‘filet mode evaluation’ of the colon, where the colon is divided along its long axis and is opened for display, giving a panoramic view of the details of the colonic lumen.

This feature gives CTC an important advantage over endoscopic colonoscopy, overcoming the presence of blind areas due to haustral folds in both forward and reverse views, thereby reducing the chances of missing polyps. We find this feature to be extremely useful. Most workstations allow simultaneous viewing of the 3D and 2D images and also provide a 3D map of the colon, indicating the position along the colon of the area being viewed. There is usually an option that enables locating a suspected pathology simultaneously, on all views and reconstructions.

There are two primary techniques for data interpretation: A primary 2D approach and a primary 3D approach, where the 2D or 3D images, respectively, are evaluated primarily with the alternative views used as a problem solving tool. In 2D imaging, the colon is ‘tracked’ from the rectum to the cecum using the supine and prone axial images that can usually be displayed adjacent to each other. Images are viewed in suitable windows for viewing the colonic wall and polyps and then in abdominal windows for evaluation of flat polyps, circumferential colonic masses and extra-colonic findings in the abdominal and pelvic organs. In 3D viewing, the radiologist ‘flies through’ the colon using the reconstructed 3D model. Residual fecal material may simulate polyps. Three signs may allow distinction of fecal material from polyps: mobility, lesion morphology and internal attenuation.

Fecal material is usually mobile, although this sign must be interpreted with caution since the colon segments are mobile and pedunculated polyps may also be mobile. Polyps may be sessile pedunculated or flat, and are usually visualized as round, oval or bilobed lesions with well-delineated contour. Fecal material exhibits commonly a geometric form with irregular sides that change between the two scans. Internal attenuation of polyps is usually homogeneous, lacking internal gas or areas of high attenuation typical of fecal material. A typical CTC study produces 700–1,200 axial CT images as well as multi-planar reconstructions and 3D views. The evaluation of this large data requires considerable time and effort.

It is important to realize that although CTC is a powerful tool for colonic polyp and tumor detection, there are many pitfalls for misdiagnosis. These include:

(1) Technical errors: due to suboptimal patient preparation with a large amount of residual stool or fluid, under distension or spasm of the colon, respiratory and metallic artifacts, image noise;

(2)Pitfalls related to evaluation technique such as incorrect window settings, 3D threshold values;

(3) Pitfalls related to reading such as failure to detect lesions and misinterpretation of findings.

When considering the performance of CTC as a possible screening technique for colorectal cancer. The new developments in data acquisition, as well as faster and more accurate image interpretation and better residual stool and fluid tagging techniques, will likely improve results, reduce cost and provide a rapid, safe, reasonably convenient method for colon cancer screening. An important advantage of CTC over conventional colonoscopy is the ability of CTC to evaluate extra-colonic structures such as the lung bases, the abdomen and the pelvis.

Fig: CT colonography-endoluminal view, 3D VRT, axial image, coronal image

 

Complications:

Until recently, it was thought that the only complications of CTC were mild to moderate abdominal discomfort due to the colonic insufflations and radiation exposure. Older age and underlying concomitant colonic disease such as inguinal hernia containing the colon, severe diverticulitis and obstructing colonic mass were present in most patients with perforation.

Conclusion:

CTC is a fast, safe, rapidly evolving examination that is accurate in detecting clinically significant colorectal polyps. The specificity and sensitivity of CTC are improving with time and are excellent for detection of colorectal tumors and polyps larger than 10 mm. Further improvement of this newly emerged technique may be expected with the introduction of techniques undergoing development, including computer-aided diagnosis, as well as better fecal tagging with electronic cleansing of the bowel, eliminating bowel preparation.

References:

·         CT and MRI of Whole Body- John R. Hagga et al, Fifth edition, 2009. Mosby Elsevier.

·         ACR practice guidelines for the performance of CT Colonography in adults- revised 2009.

·         CT colonography: Techniques, indications, findings, Thomas Manga, Anno Graser, Wolfgang Schima, Andrea Maier, European Journal of Radiology 61 (2007) 388–399.

·         CT Colonography (Virtual Colonoscopy): Technique, Indications and Performance Arye Blachar,  Jacob Sosna, Digestion 2007;76:34–41.

CANCER : Beware of it....!

Cancer

What is Cancer?
Cancer is the general name for a group of more than 100 diseases. Although there are many kinds of cancer, all cancers start because abnormal cells grow out of control. Untreated cancers can cause serious illness and death.

How does it start?

Cancer starts when cells in a part of the body start to grow out of control. Cancer cell growth is different from normal cell growth. Instead of dying, cancer cells continue to grow and form new, abnormal cells. Cancer cells can also invade (grow into) other tissues, something that normal cells cannot do. Growing out of control and invading other tissues are what makes a cell a cancer cell.