Mammography Machine

Medirays Corporation

The Mammography system – Siemens Mammomat 3000

5.1

THE MAMMOGRAPHY SYSTEM Introduction: Breast cancer remains a major cause of disability and death among women in most western

countries. In United States, the no of cases of invasive breast cancer was estimated to be

119000 in 1985 and the no of deaths 38000. In many western countries the yearly incidence is

between 75 and 95 cases per 100000 women, a trend that is increasing.

The incidence of breast cancer increases with age. The disease is very uncommon before the

age of 25. At the age of 40, the incidence of invasive breast carcinoma in the US is about 80

cases per 100000 women; at the age of 50, it is about 180 cases, and at the age of 60, 240 cases

per year.

Sensitive techniques to diagnose breast cancer are of importance for two main reasons.

There is strong evidence indicating that early diagnoses and treatment increases the

chance of completely curing the disease.

In addition, the possibility of performing a breast-preserving operation is greater if the

disease is detected at an early stage.

Mammography is a specific type of imaging that uses a low-dose x-ray system to examine

breasts. A mammography exam, called a mammogram, is used to aid in the early detection and

diagnosis of breast diseases in women.

A detailed assessment of the breast tissue by the use of low dose radiation. This investigation is

used specifically to detect masses in the breast tissue. Mammography is a tool used to assess

both non-symptomatic and symptomatic women. The first mammogram that a woman

undergoes will provide baseline information. Even when the result of this mammogram

demonstrates no abnormalities it is an invaluable tool to compare later mammograms against.

Mammograms are generally offered as a screening tool by individual countries health

departments to coincide with the ages at which a woman becomes most vulnerable to

developing breast cancer. However the tool of mammography exists so that any woman, at

whatever age, who develop a breast abnormality that would benefit from the further scrutiny

that a mammogram would offer, can undergo the procedure. Breast tissue which is under the

influence of the sex hormones. Whether these are ones produced by the body itself or those

given in the form of drugs such as hormone replacement therapy (HRT), may make the

appearance of the mammographic images denser, and consequently be more difficult to

interpret from the radiologists point of view.

http://www.radiologyinfo.org/en/glossary/glossary1.cfm?gid=3



5.2

Fig26. Mammographic images

An x-ray (radiograph) is a noninvasive medical test that helps physicians diagnose and treat medical conditions. Imaging with x-rays involves exposing a part of the body to a small dose of ionizing radiation to produce pictures of the inside of the body. X-rays are the oldest and most frequently used form of medical imaging. Two recent advances in mammography include digital mammography and computer-aided detection. Digital mammography, also called full-field digital mammography (FFDM), is a mammography system in which the x-ray film is replaced by solid-state detectors that convert x-rays into electrical signals. These detectors are similar to those found in digital cameras. The electrical signals are used to produce images of the breast that can be seen on a computer screen or printed on special film similar to conventional mammograms. From the patient's point of view, having a digital mammogram is essentially the same as having a conventional film screen mammogram.

Fig27. Digital Mammography

Tumor deep

in breast

Tumor in mammary duct

Calcified tumor




5.3

Computer-aided detection (CAD) systems use a digitized mammographic image that can be obtained from either a conventional film mammogram or a digitally acquired mammogram. The computer software then searches for abnormal areas of density, mass, or calcification that may indicate the presence of cancer. The CAD system highlights these areas on the images, alerting the radiologist to the need for further analysis.

Fig28. CAD Mammography

Screening Mammography Mammography plays a central part in early detection of breast cancers because it can show changes in the breast up to two years before a patient or physician can feel them. Current guidelines from the U.S. Department of Health and Human Services (HHS), the American Cancer Society (ACS), the American Medical Association (AMA) and the American College of Radiology (ACR) recommend screening mammography every year for women, beginning at age 40. Research has shown that annual mammograms lead to early detection of breast cancers, when they are most curable and breast-conservation therapies are available. The National Cancer Institute (NCI) adds that women who have had breast cancer and those who are at increased risk due to a genetic history of breast cancer should seek expert medical advice about whether they should begin screening before age 40 and about the frequency of screening.

Fig29. Procedure followed







5.4

Diagnostic Mammography Diagnostic mammography is used to evaluate a patient with abnormal clinical findings—such as a breast lump or lumps—that have been found by the woman or her doctor. Diagnostic mammography may also be done after an abnormal screening mammography in order to evaluate the area of concern on the screening exam.

Fig30. A Mammogram

Mammogram: A mammography unit is a rectangular box that houses the tube in which x-rays are produced. The unit is used exclusively for x-ray exams of the breast, with special accessories that allow only the breast to be exposed to the x-rays. Attached to the unit is a device that holds and compresses the breast and positions it so images can be obtained at different angles. Once it is carefully aimed at the part of the body being examined, an x-ray machine produces a small burst of radiation that passes through the body, recording an image on photographic film or a special digital image recording plate. Different parts of the body absorb the x-rays in varying degrees. Dense bone absorbs much of the radiation while soft tissue, such as muscle, fat and organs, allow more of the x-rays to pass through them. As a result, bones appear white on the x-ray, soft tissue shows up in shades of gray and air appears black. Until recently, x-ray images were maintained as hard film copy (much like a photographic negative). Today, most images are digital files that are stored electronically. These stored images are easily accessible and are sometimes compared to current x-ray images for diagnosis and disease management.



5.5

How is the procedure performed? Mammography is performed on an outpatient basis. During mammography, a specially qualified radiologic technologist will position your breast in the mammography unit. Your breast will be placed on a special platform and compressed with a paddle (often made of clear Plexiglas or other plastic). The technologist will gradually compress your breast.

Fig31. Breast compression

Breast compression is necessary in order to: Even out the breast thickness so that all of the tissue can be visualized. Spread out the tissue so that small abnormalities are less likely to be obscured by

overlying breast tissue. Allow the use of a lower x-ray dose since a thinner amount of breast tissue is being

imaged. Hold the breast still in order to minimize blurring of the image caused by motion. Reduce x-ray scatter to increase sharpness of picture.

You will be asked to change positions between images. The routine views are a top-to-bottom view and an oblique side view. The process will be repeated for the other breast. You must hold very still and may be asked to keep from breathing for a few seconds while the x-ray picture is taken to reduce the possibility of a blurred image. The technologist will walk behind a wall or into the next room to activate the x-ray machine. When the examination is complete, you will be asked to wait until the radiologist determines that all the necessary images have been obtained. The examination process should take about 30 minutes.

Fig32. Mammography image


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5.6

Siemens - Mammomat 3000 Mammomat 3000 has following advanced features:

Opdose- Optimized X ray dose – A new automatic system for beam quality selection.

Optimizes X ray dose and image quality. New Molybdenum-Tungsten anode tube for

better imaging at a lower dose.

Opcomp- Optimized compression- A new automatic compression system determines

the optimal degree of compression, based on individual breast characteristics needed to

produce uniform tauntness.

Motorized isocentric rotation of swivel arm: Motorized isocentric 180° rotation of

swivel arm with fully integrated Buckys. Making positioning for all angled views easier

and more accurate. Save time and film by changing between desired object tables

(18x24 cm or 24x30 cm) in seconds.

Automatic exposure control: (AEC) The automatic exposure control Iontomat PM with

transparency compensation guarantees optimal uniformity of film density. Siemens

patented double detector in “sandwich” design is used for measuring the object

transparency. The result is consistently high image quality, thus minimizing the no of

retakes and increasing patient throughput.

Strategically placed, the easy-to- read stand display tells the operator all relevant

positing data.

The separate free – standing generator with control console and radiation shield

provides spacing and flexibility in layout of examination room.

The control panel has an easy to read digital display for all relevant exposure data-

including error indication that automatically blocks exposure.

Stereotactic biopsy attachment: This reliable and flexible system has now been futher

improved.

Fig33. Siemens Mammomat 3000



5.7

Factors influencing the accuracy of mammography:

Technical factors

X ray equipment

Scattered radiation

Screen-film system

Film processing

Viewing conditions

Examination Technique

Positioning

Compression

No of projections

Patient factors

Ratio fact / fibro glandular tissue

Morphology of carcinoma

Observer factors

Knowledge

Experience

Fig34. Images seen on computer



5.8

The Siemens Mammomat 3000 mammography machine consists of

Stand

Generator

Control console

Radiation shield.

Fig35. Stand

Stand: • The stand of the mammography machine is the unit where the patient is in direct

contact with the machine for undergoing the scan. The stand is available in 2 versions:

-With pivoted object table arm for two different object tables and Mo X-ray tube -Same as above, but with Mo/W X-ray tube Stand consists of:

Swivel arm system:-

-X-ray tube assembly -Collimator unit -Compression device -Pivoted object-table arm with two different object tables (18x24 cm or 24x30 cm).

Fig 36. Swivel arm system



5.9

X ray tube assembly: The x ray tube of Mammomat 3000 is of 1.5M.H.U. In mammography systems either anode or cathode is grounded for patient safety since the patient is in direct contact with the machine. In Siemens Mammomat 3000, the anode is grounded while cathode has a negative potential. However in GE mammography systems the cathode is grounded while anode is at positive high potential. In Mammomat 3000, there are two anode targets, a Molybdenum anode and a Tungsten anode. Unlike x ray machines, the target material is made up of Molybdenum to lower overall patient dose and as it penetrates large or dense breasts effectively. Tungsten is chosen as a second anode material, for its superior loadability, heat tolerance and producing a tube with higher output per second. Siemens new dual metal anode (Mo+W) x ray tube has beam forming electrodes for optimal beam quality and focal spot intensity distribution. The new, interactive generator automatically suggests the specific technique and the best anode material, k-edge filter and kV combination. Also in the x ray tube assembly, there are dual metal filters (Mo+Rh) for shaping the x ray beam, which are useful for decreasing patient dose and increasing image contrast. By selecting W/Rh in appropriate cases, opdose can save upto 60% of dose over a comparable Mo/Mo exposure.

Fig37. X ray tube assembly



5.10

With Mo X ray tube

Program Compressed thickness kV value Anode/filter combination

1 0-29mm 26 Mo/Mo

2 30-44mm 27 Mo/Mo

3 45-59mm 27 Mo/Rh

4 >60mm 28 Mo/Rh Table 1

With Mo/W X ray tube

Program Compressed thickness kV value Anode/filter combination

1 0-29mm 26 Mo/Mo

2 30-44mm 27 Mo/Mo

3 45-59mm 27 Mo/Rh

4 >60mm 26 W/Rh Table 2

Collimator unit: The collimator is the best all around x ray beam restrictor. It has two advantages over the other types:

1. It provides an infinite variety of rectangular x ray fields 2. A light beam shows the center and exact configuration of the x ray field.

Two sets of shutters control the beam dimensions. They move together as a unit so that the second shutter aligns with the first to clean up its penumbra. The shutters function as two adjustable aperture diaphragms. Each shutter consists of four or more lead plates. These plates move in independent pairs. One pair can be adjusted without moving the other, which permits an infinite variety of square or rectangular fields. When the shutters are closed they meet at the center of the x ray field. The x ray field is illuminated by a light beam from a light bulb in the collimator. The light beam is deflected by a mirror mounted in the path of the x ray beam at an angle of 45°. The collimator must be mounted so that the x ray target and light bulb are exactly the same distance from the center of the mirror. Pivoted Object table: There are two object tables at three O’clock position. These object tables are of two different dimensions:

18x24 cm

24x30 cm

The object table is also known as the Bucky since it contains the cassette, grid, AEC detector and the x ray film. The swivel arm system consists of two 135° obtuse angels as shown in fig.



5.11

The scan is taken as three standard projections as follows:

Medio-Lateral-Oblique:

o Most valuable projection

o When properly performed, should include the entire breast parenchyma.

Latero-Medial:

o Permits correct localization of lesion when used with the cranio-caudal

projection.

Cranio-Caudal:

o Complements other projection

o Best for visualizing the medial half of the breast.

Hence there are two sets of labels on the object table as

L-cc L-mlo L-ml

R-cc R-mlo R-ml

The object table can be replaced with a magnification table for viewing an enlarged image of the lesion. Magnification table reduces the distance between the x ray source and the breast, thus providing us with more prominent image. It includes AEC detector, locking mechanism for the object table & a connector for electronics. The object table functions as a beam stopper also.

Fig38. Film marking



5.12

Compression Devices: The swivel arm system does compression using various compression plates. The compression plate can be controlled by:

Manual compression and decompression by the knob.

Electronically by two sets of motorized foot switches.

Breast compression is necessary in order to: Even out the breast thickness so that all of the tissue can be visualized. Spread out the tissue so that small abnormalities are less likely to be obscured by

overlying breast tissue. Allow the use of a lower x-ray dose since a thinner amount of breast tissue is being

imaged. Hold the breast still in order to minimize blurring of the image caused by motion. Reduce x-ray scatter to increase sharpness of picture.

Fig39. Compression devices



5.13

Fig40. Control panel



5.14

Control Panel: 1. Mammomat 3000 ON/OFF

2. Exposure release buttons with green lights. Both buttons must be pressed during the

entire exposure. This is to ensure that the operator is standing behind the radiation

shield during the exposure.

3. +/- kV selection and display

4. +/- mAs selection and display. In AEC mode, the display remains dark before the

exposure. After the exposure, the mAs value reached during radiography is indicated.

5. +/- Film density adjustment and display.

6. AEC. These buttons are used to activate AEC mode and to select screen /film systems. H

stands for high speed and D for detailed screen.

7. Button for selection of anode/filter combination in manual mode.

8. Button for selection of one of four pre-programmed exposure parameter setting

9. Button for storing exposure parameters

10. Button to select/deselect Auto mode

11. Button to select/deselect automatic decompression after exposure. When OFF, use foot

switch or the knobs for manual decompression

12. Limit button (Acknowledgement). Serves to reset the system after errors, indicated by

an error code, or faulty exposures (limit errors), indicated also by the limit lamp and

acoustic signal

13. Limit lamp. Flashing- Tube is temperature is above normal

14. Cassette is missing or needs to be replaced (it has already been exposed)

15. Object table or object table arm is not locked in position

16. Risk of collision between tube head and floor. In stereotactic mode: the tube head is not

in 0° or +/- 10° position

17. AEC detector not in chest wall position (only in stereotactic mode)

18. Diaphragm not in correct position. In stereotactic mode: external diaphragm not in

position

19. Focal spot indication. Indicates focus in operation. Small focus is automatically selected,

when a magnification table is used.

20. Green light indicates that the unit is ready for exposure. This indicator has the same

function as the green light on the stand display and the exposure release buttons.

21. Yellow light and an acoustic signal indicate radiation ON.



5.15

Stand display:

Optimal compression Compressed Thickness Angle of Swivel arm system Operating Modes: Mammomat 3000 works in 5 different modes:

1. Manual mode-

The kV values are set manually

The mAs values are set manually

The anode/filter combination is already set

2. AEC mode

AEC stands for Automatic exposure control mode.

Desired kV is set.

High speed screen or detail screen is selected.

The mAs is already set.

Anode/filter combination is set

3. Program mode

In this particular mode there are four different programs for different intervals

of breast thickness.

There are pre-programmed values stored in each button.

H or D is also included. I.e. high speed and detail screen.

There is a store button is used to store the desired values.

4. Automatic program selection mode

In this mode the kV, density ,anode/filter, H/D combination are automatically

selected according to breast thickness.

Still adjustments can be made.

5. Stereotactic mode

There is a Knob used to push to tilt the swivel arm.

The needle-syringe is placed to take the specimen of the lump.

This process is also known as Biopsy.



5.16

Errors and their rectification: Er-004 communication master IONTOMAT faulty:

Description:

Master processor (D-702) can not activate IONTOMAT(D-701) via serial interface

Fault elimination:

Check if pc board plugged correctly and if serial interface functions correctly.

Er 011: Exposure has been stopped

Description: If the exposure buttons are released prematurely, the exposure aborted immediately. The LIMIT LED lights up. An acoustic signal sounds. Fault Elimination: Indication for no further action. Check the contacts of the exposure release buttons. Change the buttons if this error appear frequently.

Er 825: Pot missing Error

Description: There are four potentiometers in the stand for tube angle, preset angle, preset force and thickness. If any of the pot is not functioning then the display will show this error. Fault Elimination: Check that all pots function properly. If all pots are function properly, check the programming of pot check and correct it.

Er 524: BR8 on D701 missing

Description: After switching on IONTOMAT checks impedance at the input on the D70. If the value is incorrect, this error is generated. Fault Elimination: Check whether jumper BR8 on the D701 board has been plugged in correctly. Or replace board D701

Er 524: BR8 on D701 missing

Description: After switching on IONTOMAT checks impedance at the input on the D70. If the value is incorrect, this error is generated. Fault Elimination: Check whether jumper BR8 on the D701 board has been plugged in correctly. Or replace board D701



5.17

Documents

Mammography Machine