We are from Adyar Cancer Institute Chennai 20. A magnificent hospital providing state of the art cancer care for over 100,000 patients annually. Celebrating Diamond Jubilee and it has several firsts.

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2D REAL SIZE IMAGING TECHNIQUE.

BYG. Yogananthem and C. Palanivelu

Cancer Institute, Adyar, Chennai

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2-D measurement error we left behind

Medical imaging technique is well advanced today and we are measuring signals from protons level in MRI imaging. But we left behind

a error in 2-D measurement in digital X- ray in imaging. This we found out during imaging of Scanogram. In this presentation we are explaining that how we are controlling this error by applying small trick for given plane interest on the digital X-ray Scanogram image.

2-D measurement displayed in the Digital X-ray monitor is incorrect

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For experimental proof, we developed a wax phantom by keeping 5 lead balls in plane such that 100 mm distance is kept between the first and fifth lead ball and the plane is at unknown height from the bottom (the plane of interest).

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To prove geometrical error we did the imaging in DX and CT on the same phantom.

Getting ready CT AP Scout Getting ready DX AP view

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CT AP SCOUT VIEW OF THE PHANTOM.

We did AP scout view of this phantom and the distance between the first and fifth lead ball is measured in straight line and the distance is 100 mm. Due to slit beam technology there will not be any geometrical error. The measured distance is displayed at bottom of the monitor.

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Digital X-ray AP view

This image is obtained by AP view of same wax phantom exposed in digital X-ray equipment (Defineium TM 6000) The measured distance is 114.2 mm and not 100mm. Due to geometrical error it is 14.2% more .

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scanogramScanogram is a special type of X-ray to measure the bone length. In orthopedic field the Scanogram are used to measure real size or length of the bone. An accurate and reproducible assessment of limb length is required for successful treatment.

Scanogram by using conventional x-ray equipmentGeometrical error exists from conventional X-ray period and all technical people are managing it by keeping lead rulers at anatomy level and 6 feet film focal distance. They measuring the length of the long bone with the help of scale projected over the film or image.

Digital X rays are widely used and images on the films are either magnified or reduced. With the help of workstations and CPU the distance of the required images are measured and these measurements are inaccurate and discomfort of taking scanogram started here and we are not able increase FFD beyond 40 inches in table x ray. Because of these reasons many of our orthopedic doctors are not ready to give up conventional x ray machines.

X-Ray Image

The digital medical X-ray image is superimposed image of multiple planes our body.

In digital X-ray equipment, 2D Measurements are inaccurate since they are measured at a detector level and not at an anatomical level.

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The plane away from the detector will have higher magnification and plane near to the detector will have least magnification. Tan angle formula can be used to know correct 2-D measurement.

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We have developed a technique , for long bones, where we can get images without geometrical errors and images are imaged in the film as real size for the given plane of interest. We can measure the actual length of the given anatomy with the help of an ordinary measuring ruler on the film itself .

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We can call this as real-size imaging, when the virtual ruler readings on the film matches (coincide) with external ruler for the given plane of interest.

Virtual ruler in the DX image

External ruler readings matches with the virtual readings

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REAL-SIZE IMAGING IN FOUR STEPS BY USING DX

1. DESIGN A LEAD RULER .

2. SELECT THE PLANE OF INTEREST 3. POSITION THE ANATOMY 4. CONTROL ZOOMING ON THE MONITOR

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STEP 1. Take a lead ruler and keep it over a processed film from laser camera as shown below. Measure the width of exposed area of the film and keep two pointers or markers such that distance between is equal to the width of the exposing area of the film by omitting the border.

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STEP 2. Select the plane of interest by using axial cut of CT image or lateral CT Scout image.

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STEP 3. Position the anatomy (Long bone) parallel to the detector by keeping pads. Keep the designed lead ruler by side at the level of plane of interest as shown below and expose. This will help us to get parallel or equal magnification of long bone and lead ruler and thus we get some control or idea of magnification of the plane of interest.

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STEP 4. Expose the images in landscape format by using laser camera. The arrows shows the pointer or marker location on the X-ray image. Now we have to zoom the images in such a way so that both the pointers should touch or reach the upper and lower limits of film format. Then give print in order to get real size imaging film from the camera.

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This is video demo of zooming of exposed images on laser film format by using advanced work station.

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This is one of the real size imaged film from the camera. We brought same sample films for display

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CT images do not have geometrical error. Matching image width and film format width we can produce real size imaging on the film by integrating laser camera and advance work station by feeding simple software. The following film is an example real size images on the film did manually.This CT film shows cerebral

hemorrhage in multiple film formats. All images are equally zoomed in real size. The size of the hematoma will be easily measured with the help of ordinary ruler on the film itself for the treatment and to comparing with the CT films repeated later.

The same method is adopted to get the multiple real size images on the same film for MRI images also.

CT guided J needle biopsy is the procedure of taking tissue for study in operation theater. For this, one lead marker is placed on the body and one axial cut is taken. Radiologist marks the entry and distance for the procedure. Only one measurement is on the film. In some cases surgeon may select another entry at the last minute. In such cases , real time image will help them to select another entry and this real time film will help to select and measure on the film itself by the ruler

The below picture shows comparison of different modality images on single film with real size imaging. The breath of film is matched with lengths of images. Each modality is best at giving its own details

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We applied for patent right for this methodology and it is under process.

ATTENTION TO MANUFACTURES

WE PROVED 2-D MEASUREMENT IN DX AT DECTECTOR LEVEL IS IN CORRECT AND KINDLY UPLOAD TAN ANGLE SOFT WARE SO THAT CUSTERMERS CAN AWARE AT WHAT HEIGHT FROM DETECTOR ARE MEASURING.

KINDLY INTAGRATE LAZER CAMERA AND ADVANCE WORK STATITION SO THAT AT SINGLE TOUCH TECHNOLOGIST CAN GET REAL SIZE IMAGING.

ConculsionsWe proved, all Digital X ray equipments provide inaccurate 2D measurements, since they are measured at detector level and not at an anatomy level.By feeding Tan Angle software, we can compute accurate 2-D measurements at desired anatomy level.By matching film size and image size we can produce real size CT and MRI images on the film.By matching Screen size and image size we can produce real size images in PACS monitor also. we are developing soft wares for all above purpose.

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THANKS TO DR.V.SHANTA EXECUTIVE CHAIRMAN CANCER INSTITUTE, ADYAR, CHENNAI, INDIA DR.A.V.LAKSHMANAN, ADVISOR CANCER INSITITUTE DR.KATHIRESAN, HOD, SURGICAL ONCOLOGY CANCER INSTITUTE DR.G .SELVALUXMY , ADDITIONAL DIRECTOR CANCER INSTITUTE ALL STAFF MEMBERS, RADIOLOGY CANCER INSTITUTE

THANKS TO

NCISRT AND ALL MEMBERS AND AUDIENCE

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