Comparison between mammogram and mri in detecting breast cancer

The study is to to evaluate the accuracy of MRI compare with mammography in detecting breast disease or pathologies.

http://www.slideshare.net/nordin1808/comparison-between-mammogram-and-mri-in-detecting-breast-cancer-21878463#

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INVASIVE DUCTAL CARCINOMA - Case study

1.      SUMMARY

      Invasive ductal carcinoma (IDC) is one of a type of cancerous or malignant tumor which relates to the breast’s milk ducts and if it is not treated, will be high possibility to spread to other parts of the breast or body.  The symptom of IDC could be having hard immobilize lump but does not hurt.  The case report regarding one women age 47 who came to the hospital having several symptoms.  The doctor than do clinical breast examination on her.  Based on the examination, characteristics of the lump on the right breast was noted.  Patient was immediately asked to do mammogram for diagnosis.  Mammogram finding shows a suspicious spiculated lesion and patient was suggested to go for breast ultrasound as an adjunct to mammogram.  Based on the characteristics of the lesion from mammogram and ultrasound examination, radiologist concluded that the lesion found in the right breast fall into BI-RADS category five which is highly suggestive of malignancy.  Then, biopsy of the right breast lump was done and laboratory report confirmed the malignancy.  Because of the confirmed malignancy, mastectomy of the right breast was carried out.  Patient also went other treatment as well such as radiation therapy to prevent cancerous cell from spreading to another part of the body.  Patient should come for checkup annually as a preventive measure.         

2.      INTRODUCTION

      The female breast consists of fat, fibrous or connective tissue, glands, 15 to 20 lobes and smaller lobules, and the tiny ducts.

      Breast cancer is called invasive when the cancer spreads outside the membrane of the lobule or duct into the breast tissue and spread into the lymph nodes in the armpit area or beyond (invasive breast cancer: symptoms, treatments, prognosis, 2005).  There are two types of invasive breast cancer which include invasive ductal carcinoma (IDC) and infiltrating (invasive) lobular carcinoma (ILC).  Invasive ductal carcinoma is the common type of invasive breast cancer which accounts for 80 percent of invasive cancers.  While infiltrating lobular carcinoma only accounts for about 10 percent to 15 percent of invasive breasts cancers (invasive breast cancer: symptoms, treatments, prognosis, 2005)       

2.1  Definition of Invasive Ductal Carcinoma (IDC)

            Invasive ductal carcinoma is a type of cancerous or malignant tumor which relates to the breast’s milk ducts and is able to spread to other parts of the breast or body (breast cancer, 2011).  Ducts are the part of the breast through which milk flow.  IDC always starts developing in the breast’s milk ducts, but breaks out of the duct tubes and invades surrounding breast tissue.  IDC if not treated at an early stage can invade into the bloodstream or lymphatic system spreading cancer cells to the other parts of the body (Stephan, 2012).

            Invasive ductal carcinoma is more common to affect a woman as they grow older, yet women at any age may also be affected.  Author from invasive ductal carcinoma (2012) noted that about two-third of women are 55 or older when they are diagnosed with this cancer.

2.2  Etiology

            From breast cancer: causes (2012) the researcher noted that it is not clear what causes breast cancer.  They know that when some breast cells begin to grow abnormally, breast cancer will occur.  These cells, rapidly divide more than healthy cells do and continue to build up, forming a lump or mass (breast cancer: causes, 2012).

            However, Chen (2012) stated that estrogen causes the breast cancer tumor to grow because many breast cancer cases are sensitive to the hormone estrogen and such cases have estrogen receptors on the surface of their cells called estrogen receptor-positive cancer or ER-positive cancer.  Certain women have HER2-positive breast cancer.  HER2 is a gene that help cells grow, divide, and repair themselves and when cells have too many copies of this gene, they will grow faster (Chen, 2012).  Chen (2012) noted that women with HER2-positive breast cancer have more aggressive disease.

            Risk factors of breast cancer include age and gender, family history, genes, menstrual cycle, alcohol use, childbirth, hormone replacement therapy, obesity, and radiation (Chen, 2012).

2.3   Sign and Symptoms

            Many researchers reported that early breast cancer is asymptomatic.  However, as the cancer grows, symptoms may occur.  One of these symptoms is breast lump that is hard, has uneven edges, and does not hurt.  Other symptoms are changes in the size and shape of the breast or nipple and fluid coming from the nipple (Chen, 2012).  In advanced breast cancer, the symptoms include bone pain, breast pain or discomfort, skin ulcers, swelling in the armpit, and weight loss (Chen, 2012)

3.      .  CASE REPORT

3.1  Patient History

            A woman, 47 years old came to the hospital with complain of having lump in the right breast and feel discomfort with it.   She is married and has four children.  She never did mammogram before or any breast surgery.  She has second degree family history of breast cancer which was her aunt from fraternal site.  She’s already menopause and not on hormone replacement therapy (HRT). 

            She was referred to a breast surgeon and that breast surgeon did clinical breast examination (CBE) on her.  The breast surgeon palpate both breasts to compare.  During palpation she feels the lump.  The lump is in the upper outer quadrant of the right breast.  The lump felt like a gritty texture and immobility.

            Breast surgeon suggested for clinical follow up and patient was asked to do mammogram as an adjunct to the physical examination for further evaluation.                   

3.2  Diagnosis

3.2.1        Mammogram

      Mammogram result reported by Dr Asokan Raman Nair showed a 2 x 1.5 cm lesion in the right upper outer quadrant which has spiculation.  No microcalcifications seen.  No other focal lesion seen.  The left breast has normal appearance.  No enlarged lymph node seen.  The 2 x 1.5 cm speculated lesion in right upper outer quadrant is suggestive of a carcinoma. 

      Breast ultrasound was suggested as an adjunct to mammogram by Dr Asokan Raman Nair to diagnose whether the lesion is solid or cystic and to confirm the malignancy.  Appendix one shows diagnostic imaging report of mammogram.           

3.2.2        Ultrasound

      The patient did the breast ultrasound on the next day.  Ultrasound of the right breast was performed by Dr Vimalah Rathakrishnan.   

      Report showed there are two benign type lymph nodes noted in the right axilla and these show large fatty hilla.  In the superior lateral quadrant of the right breast, along 10 o’clock line, about 1.5 cm from the areolar margin, there is a 9 mm x 7 mm focal lesion with marked posterior acoustic shadowing.  This nodule is solid and shows markedly microlobulated margins.  There is stromal distortion around this lesion.  Ultrasound features are consistent with a malignant nodule.  The position of this nodule was marked on the skin.  For the conclusion, there is focal solid nodule in the superior-lateral quadrant of the right breast along 10 o’clock line has ultrasound features of a focal malignancy.  Appendix two shows diagnostic imaging report of breast ultrasound.

      Biopsy was suggested for further investigation. 

3.2.3        Biopsy

      Depend on the marking that was made during breast ultrasound, the suspected right breast nodule was biopsies under ultrasound guidance by Dr Vimalah Rathakrishnan.  The specimen was sent to histopathology laboratory for the result.

      Histopathology report came out three days later showed macroscopic appearance of right breast lump consists of a piece of fibro fatty tissue measures 50x40x30 mm.  Cut section showed irregular fibrosis with small myxoid nodule measures 15x10x15 mm.  Margin is very near about 2 mm.  One section submitted for frozen section.  Histology report of frozen section showed sheets and strands of invasive ductal carcinoma tumor cells with moderate nuclear pleomorphism and few tubules formation.  Few mitotic figures are seen.  The interpretation for biopsy of this right breast lump is invasive ductal carcinoma (IDC).  Histopathology report was reported by Dr Norraha Abd Rahman.  Appendix three shows histopathology report of the right breast lump.           

3.3  Patient’s Progress

            Patient was informed about the report where it was confirmed invasive ductal carcinoma of the right breast.  Mastectomy was suggested by breast surgeon before the extent malignant cells spread to another part of the body.  Patient agreed and mastectomy was carried out in operation room.  Right mastectomy specimen with axillary contents was sent to histopathology laboratory to see if there any metastatic carcinoma spread from the right breast lump.  The result showed right mastectomy specimen with axillary contents residual small focus of ductal carcinoma in situ component of low grade with lymph nodes metastasis.  Margins are free.  Appendix four shows histopathology report of the right mastectomy specimen.       

                 

4.      DISCUSSION

      Appendix five shows figure 1 – 5 and appendix six shows figure 6 – 11.    

      Noted that the risk factors of breast cancer are hormone related risk factor, lifestyle factor, and genetic risk factor (Rusiecki et al., 2005).  Hormone related risk factors include age at menarche, parity, age at first full-term pregnancy, breastfeeding history, menopausal status, and age at menopause.  Lifestyle factor is like alcohol consumption and elevated body mass index.  Genetic risk factor is family history.  For this patient, some of the risk factors mentioned can be the cause of breast cancer.  Mentioned earlier that patient already menopause and according to Henderson (2006) most breast cancer occur during the postmenopausal years.  Another factor that is important is family history.  Although patient doesn’t have family history of breast cancer in a first-degree relative who is mother, sister, or daughter, but she has family history of breast cancer in a second-degree relative which was her aunt.   Park et al. (2008) noted studies have shown that having a history of breast cancer was positively correlated with a higher perceived risk of breast cancer.

      Before proceeding to mammogram, health professional, breast surgeon will do clinical breast examination (CBE) on patient first.  Mayer, Batur, and Moore (2010) mentioned that the range of cancers detected by CBE but not by mammography was three percent to 45 percent. The surgeon examined patient’s breast for any abnormalities in size or shape and changes in the skin of the breasts or nipple.  Then, she gently palpate the breasts using the pads of the finger.  She will check the location of any lump and whether the lump is attached to the skin or situated deeper in the tissue.  Other than that, is to examine on the axillae and chest wall for lymph nodes.  According to radiologist, Dr Asokan (personal communication, May 02, 2013), if there is present of lymph nodes noted, patient is in high risk for breast cancer.  However lymph node is usually very tiny and difficult to detect.  If the surgeon can feel the lymph node, that means the lymph node has already grown larger, probably patient already have breast cancer and the cancer had already spread to the lymph node.  As for this patient, the surgeon cannot detect any large lymph node during palpation but there was suspicious lump felt at the outer upper region of the right breast.  The surgeon examined the character of this lump and found out that the lump was gritty in texture and immobilized.  According to Mayer, Batur, and Moore (2010), characteristic of lump that suggest cancer through palpation include, immobility, an irregular border, a hard or gritty texture, and a size greater than two centimeter.    

  

      For this patient, mammogram was recommended for her.  This is because mammography is the gold standard imaging procedure for detection of early cancer and patient is already 47 years old and had never done mammogram before.  This patient should have done mammogram examination seven years ago when she turned 40 years old.  Mammogram is recommended for patient age 40 and above because patient age below 40 tend to have very dense breast tissue which make mammograms image difficult to interpret.  However for patients who are at high risk for developing breast cancer such as patient with a strong family history of breast cancer, screening from age 30 is recommended (mammograms in special circumstances, 2013).     

      Four standard images had been taken.  They are right cranio caudal (cc) view, left cranio caudal (cc) view, right medio lateral obliques (MLO) view, and left medio lateral obliques (MLO) view.  Because there was a suspicious appearance found on the right breast, radiologist asked for an additional view which is magnification view of the right breast on cc view or can be called as right cc mag as shows in figure five.  Magnification view is very helpful in identifying a true spiculated mass on a mammogram (Peart, 2005).     

      According to Komen (2012), for an assessment of breast density, there are four different types of breast density shown in the mammography images. These four types are fatty breast type, some breast density type, more breast density, and dense breast type.  Komen (2012) noted that these varying breast densities ranging from images of breasts with more fat and less breast tissue (refer to fatty breast and some breast density types) to images with less fat and more breast tissue (refer to more breast density and dense breast types).  This patient’s breast images fall into some breast density type category where images showed more fat than the breast tissue.

      However the American College of Radiology (ACR) has developed a different way of describing the breast density.  This is by using Breast Imaging Reporting and Data System (BI-RADS) and this patient’s breast density fall into BI-RADS two category.  Breast density is classified by BI-RADS into four groups.  BI-RADS one, ‘the breast is almost entirely fat’.  BI-RADS one means that fibrous and glandular tissues makes up less than 25 percent of the breast.  BI-RADS two, ‘there are scattered fibroglandular densities’, means that fibrous and glandular tissue makes up from 25 to 50 percent of the breast.  BI-RADS three, ‘the breast tissue is heterogeneously dense’ and has more areas of fibrous and glandular tissue which is from 51 to 75 percent throughout the breast.  Lastly, BI-RADS four, ‘the breast tissue is extremely dense’ with more than 75 percent fibrous and glandular tissue made up the breast (mammogram report – BIRADS, 2013).      

      There are four quadrants of the breasts which are upper outer quadrant, upper inner quadrant, lower outer quadrant, and lower inner quadrant.  Cranio caudal (cc) view of the breasts show outer and inner quadrant as shown in figure one and figure two.  Outer quadrant is the portion adjacent to the armpit area while inner quadrant is the portion adjacent to the chest wall.  Medio lateral oblique (MLO) view of the breasts shows upper quadrant and lower quadrant.  This can be seen in figure three and four.  Portion above the nipple is upper quadrant while below the nipple is lower quadrant.  The suspicious lesion that was reported is seen on the right breast, in cc view which is located on right outer quadrant of the breast as shown in figure one.  While in MLO view, it is located on right upper quadrant.  This can be seen in figure three.  Overall, the lesion is located on upper outer quadrant of the right breast.  Many researchers stated that from their studies most of the tumor found is at the upper outer quadrant.  Kwong (2003) mentioned that it is the most common place on the breast to have tumor is the upper outer quadrant where 36 percent of tumors are found. 

      Other than that area, both left and right breasts showed normal appearances.  Normal appearance shown means that pectoralis muscle of both right and left breasts are clear where there is no enlarged lymph node seen as reported by radiologist.  Adipose tissue also looks normal on both breasts.  The ducts and glandular tissue of the left breast showed normal appearance where there are no spiculated lesions seen as shown in figure two and four.  There are no microcalcifications seen on both breasts.

      According to Peart (2005) spiculated lesions have a solid central tumor with radiating structures and ill-defined borders.  As reported by radiologist, Dr Asokan Raman Nair, from mammogram images there is spiculated lesion in right upper outer quadrant. This lesion measured 2 x 1.5 cm.  As show in figure one and figure three or more clearly in figure five the lesion is white, more enhance than surrounding tissue and it is stellate in shape.  Stellate means the shape is irregular and looks like a ‘star’.  Figure five also shows that the lesion has ill defined borders and showed that it is a true spiculated lesion because in a true spiculated lesion the widest diameter of the radiating extensions occurs at the tumor margins and then tapers distally.  According to radiologist, surrounding the lesions, the breast tissue showed a little distortion compared to the left breast in figure two where the appearance of the breast tissue is smooth and no distortion.   This abnormal finding suggested of invasive ductal carcinoma (IDC).  Broder and Lieberman (2005) noted that on mammography IDC can have a wide range of appearances and in some women it might show slight architectural distortion of the breast tissue.  The masses or lesions representing IDC usually have any size, irregular shapes, micro-lobulated, ill-defined or spiculated borders and sometime there is presence of pleomorphic microcalcifications (Broder & Lieberman, 2005).  Breast cancer (2011) reported that IDC is characterized by a hard lump.  The lump will feel harder, firmer, and more anchored than a benign breast lump.  Over the affected area or the nipple, the skin may be retracted (pulled in) (Breast cancer, 2011).  Noted that there is asymmetry of the breast tissue when comparing right breast (figure one) and left breast (figure two) because in right breast, the breast tissue posterior and anterior to the spiculated lesion have been retracted by the lesion itself.  This can be seen clearly in magnification view, figure five.

      As a whole, characteristics of malignant spiculated lesion in mammogram shows distinct central mass, sharp, dense, fine lines of variable length radiating in all directions, spicules reaching the skin or muscle may cause localized skin thickening or skin dimpling, and sometime it is associated with malignant type calcifications (Peart, 2005).  Characteristics of malignant spiculated lesion are different when compared with benign characteristic of spiculated lesion.  For benign it shows no solid, dense, or distinct central mass, it may have translucent oval or circular area at the center.  It only have very fine linear densities or lower density spicules and it is never associated with skin thickening or skin retraction (Pear, 2005).        

      Based on the characteristics of the lesion, radiologist concluded that the lesion found in the right breast fall into BI-RADS category five which is highly suggestive of malignancy.  BI-RADS is a standard way of describing mammogram findings which developed by the American College of Radiology.  There are few categories to describe mammogram findings using BI-RADS.  BI-RADS category one, ‘negative’ used when nothing bad was found and no significant abnormality to report.  BI-RADS category two, ‘benign finding’ used when radiologist choose to describe a finding known to be benign such as fibroadenomas.  BI-RADS category three, ‘probably benign finding’ shows finding that have a very good chance of being benign but it is not proven to be benign, so follow up after six month is recommended.  BI-RADS category four, ‘suspicious abnormality’ shows finding that do not look like cancer but could be cancer and radiologist always consider biopsy for this category.  BI-RADS category five, ‘highly suggestive of malignancy’ showed finding that looks like cancer and have high chance of being cancer.  For this category, biopsy is very strongly recommended (mammogram report – BIRADS, 2013).                

      Ultrasound of the right breast was suggested as an adjunct to mammography.  This is to confirm the malignancy of the lesion mentioned in mammogram and to further evaluate the breast lesion and surrounding breast tissue.  Other reason of doing breast ultrasound is to distinguish between cystic or solid mass.

      Anatomy of the breast shown in ultrasound are skin, three layers of breast tissue, muscle layer, chest wall, pectoralis muscle, nipple, axillary tail, and ribs (Lopchinsky, Van, & Kattaron, 2000).  There are three layers of breast tissue in breast ultrasound images.  The first layer is premammary fat layer which is situated below the skin, second layer called mammary layer, and third layer where is near to the chest wall is retro mammary layer.  Sonographically, breast tissue layers in pre menopausal women is different from breast tissue layers in post menopausal women.  For this patient, her breast ultrasound images show breast tissue layers that in postmenopausal women, figure 10.  Figure 11 shows example of ultrasound image of breast tissue layers that is in premenopausal women. 

      In ultrasound, lesions can be divided according to their shape, margins, echo characteristics, echo texture, and effect on the through transmissions of sound (Kopans, 1998).  Benign lesions usually are round, oval, or smoothly lobulated. Whereas malignant lesions are irregular in shape, ill defined, or very lobulated.  Radiologist mentioned that images that are brighter from highly reflective surfaces are called hyperechoic while areas that are less reflective will appear as darkened regions are said to be hypoechoic.  Areas that have similar echogenicity are said to be isoechoic to each other.  Kopans (1998) noted that cancers usually always hypoechoic compared to the tissue surrounding them and they are even lower in echogenicity than fat.  Occasionally cancers are isoechoic with the surrounding tissue.  Benign lesions on the other hand are hyperechoic (Kopans, 1998).             

      For this patient, radiologist noted that there was focal solid nodule in the superior lateral quadrant of the right breast along ten o’clock line, situated about 1.5 cm from the areolar margin and this solid nodule has a feature of a focal malignancy.  This can be seen in figure seven.  Areolar margin is the area surrounding the nipple.  In breast ultrasound images, radiologist noted that the location of the lesion is depending on clockwise.  For both right and left breasts, 12 o’clock and six o’clock is always deemed superior and inferior part of the breast.  For right breast, nine o’clock determine lateral part of the breast while three o’clock determine medial part of the breast.  Medial part is the one that is near to the chest wall.  However for left breast, it is opposite where nine o’clock determine the medial part of the breast and three o’clock in lateral part of the breast.  As for this patient, the lesion is situated along ten o’clock line of the right breast according to radiologist.  Ten o’clock is somewhere between nine and twelve o’clock, so for the right breast where nine o’clock is consider lateral part and 12 o’clock is superior part, meaning that the lesion was found in the superior lateral quadrant of the right breast.

      The focal lesion mentioned by radiologist was 9mm x 7mm in size with marked posterior acoustic shadowing.  According to Rudy (2013), size is not a factor in benign and cancerous breast growth.  However, posterior acoustic shadowing was believed to be a characteristic that defined a malignancy (Kopans, 1998).  Figure seven shows the hypoechoic focal lesion with a posterior acoustic shadowing.  It is noted that the appearance of the lesion is taller than the width.   Other than that it also has an ill defined border, an irregular shape, and spiculation which appear as a hyperechoic ‘band’ around the mass.  This can be seen clearly in figure nine.  This nodule is also solid and shows markedly microlobulated margins according to radiologist as shows in figure eight and nine.  There is also stromal distortion around the lesion, which can be seen in figure eight and nine.  All this characteristics shows suggestion that the nodule is malignant. 

      According to Halls (2010), ultrasound characteristics of benign and malignant solid breast nodule is different.  When that nodule is benign, ultrasound confirmed absence of malignant findings, hyperechoic or intense and fibrous tissue like feature, shows two or three macrolobulation, it is ellipsoid in shape, wider than taller appearance, parallel to the skin, and sometime it is echogenic and well circumscribed (Halls, 2010).  As for potential malignant nodule, ultrasound characteristics, there will be spiculated outline with alternating echopenic and echogenic straight lines radiate from the mass, taller than it’s width because cancers often spread vertically and become taller than the width, shall also have shadowing because the sound beam fail to pass through the lesion, has a duct extension pattern because cancer tends to expand toward the nipple within a duct, and shows microlobulation on the borders (Peart, 2005). 

      Spiculations on ultrasound often consist of straight lines that radiate in a perpendicular fashion from the surface of the breast mass.  Taller-than-wide characteristic suggest of malignancy because one can conceive that the mass caused by malignancy is aggressive enough to overcome normal breast tissue barriers and planes, and grow vertically (Halls, 2010).  This is because when doing ultrasound, patient lies supine which make the normal breast tissue planes should have a horizontal orientation except for this malignant tissue.  Microlobulations that are shown on breast ultrasound indicate the presence of lots of very small lobulations, usually 1 mm to 2 mm on the surface of a solid breast nodule.  If the number of microlobulations increase, the probability that the breast mass is malignant also increases (Halls, 2010).  If there is posterior acoustic shadowing on ultrasound, that’s mean something about the mass or lesions attenuate the sonic beam strength when compared to surrounding normal tissue.  Posterior acoustic shadowing is suspicious for malignancy because most benign tumors do not usually shadow unless they are calcified (Halls, 2010).

      Previously, radiologist did mention that there is stromal distortion around the lesion.  Stromal distortion is one of the abnormal sign on ultrasound and mammogram as well.  Stromal is a cell that is connective tissue cells of any organ that support the function of the parenchymal cells of the organ (stromal cells, 2013).  Other than that, radiologist also mentioned there are two benign type lymph nodes noted in the right axilla which can be seen in figure eight and nine.  Normal lymph nodes have the same ultrasound appearance which are hypoechoic, with an echogenic hilus, and generally oval.  While the malignant lymph nodes are usually hypoechoic without an echogenic hilus, and round in shape.  According to Kopans (1998), for most of the parts these tumors grow first within the duct system.  As they enlarge they develop the ability to break out the duct and infiltrate into the periductal stroma and gain access to the lymphatics and vascular structures, and spread to axillary and lymph nodes.  That is why lymph node can be seen in ultrasound eventhough they are still benign.

      Benign and malignant lesions of the breast are categorized by the level within the duct network in which they occur.  Some processes are categorized as if they arose from the cells of the ducts, while others from the components of the lobules (Kopans, 1998).  For this patient, histopathology report confirmed that the lump or lesion mentioned arose from the cells of the ducts which give the interpretation of the right breast lump was invasive ductal carcinoma.  Invasive ductal carcinoma is the most common form of invasive breast cancer and the primary lethal cancer of the breast (Kopans, 1998).  It can be developed from in situ cancer or develops directly.  The cytologic characteristics of the tumor and its growth pattern suggest an origin in ductal epithelium.  According to Kopans (1998), many invasive cancers likely obliterate any residual in situ component, but the in situ clones that are not destroyed by the invasive cells can continue to grow in and down the ducts, presenting invasive and in situ cancer in the same lesion.      

      During a biopsy procedure, radiologist remove cells or tissues from the suspicious area for the pathologists to examine more closely in the laboratory.  The pathologists examine the tissue sample under a microscope and assign a histologic type and tumor grade.  Grade one means that cancers tend to grow the slowest, while grade three shows tumor spread more aggressively.  Other than that, pathologist also realised the size of the tumor, how closed the cancer is to the edge of the tissue removed, and whether the tumor invaded blood or lymphatic vessels.

      Invasive ductal carcinoma is treated through surgery, chemotherapy, hormonal therapy, or radiation therapy.  For this patient, she chose surgery. Mastectomy of the right breast was immediately being carried out where the entire breast and some or all lymph nodes near the breast were removed.  Mastectomy reduces the chances of the cancer to recurr.  Even after undergoing mastectomy, usually most women with invasive breast cancer will be offered chemotherapy and hormonal therapy.  Chemotherapy drugs will kill rapidly dividing tumor cells that may be spreading through the body reducing the risk of the cancer coming back in another site of the body.  Drugs affecting hormone also kill the tumor cells, which require hormones to grow, and prevent these cells from spreading or coming back.  Radiation therapy is used to rid the body of any microscopic remnants of the cancer in the area where the original tumor was found and removed (breast cancer, 2011).

      Once the diagnosis and treatment has been made, patient’s prognosis should be understood.  The prognosis will depend on a few factors and one of these factors is the type of tumor and the size of the tumor.  The larger the invasive tumor, the worse will be the prognosis.  Second factor is lymph nodes, where involving more lymph nodes, the worse will be the prognosis.  Third factor is margin.  Margin refers to the distance between the tumor and the edge of the surgical specimen.  Other factors are hormone receptors, differentiation or grade, lymphatic invasion, and cancer genes (breast cancer, 2011).

5.      CONCLUSION

      After being diagnosed and treated, patient is doing very much better.  No matter how, this patient was still being advised to undergo radiation therapy as a preventive measure.  Patient was also reminded to come back within six month after last mammogram to check on the other breast to make sure cancerous cell does not spread to that breast.  If the result is normal, she is advisable to come for annual checkup for clinical breast examination, unilateral mammogram, and ultrasound breasts.  The patient may have high tendency to start having side effects or complications from those cancer treatments.  For example, radiation therapy may cause temporary swelling of the breast (lymphedema), aches, and pains around the area (breast cancer, 2012).           

      Now with advanced technologies, there are a lot of improved treatments that can help women with breast cancer to survive much longer than before.  Even though, breast cancer still can spread to other parts of the body.  Sometimes, even after the entire tumor has been removed and lymph nodes are found to be cancer free, cancer still can return and may recurr.  That is why many health practitioner will suggest to all women to go for breast checkup every year so that if there is cancer cell, we can detect it and treat it before the cancer get worse and start to spread to other parts of the body.  Women under 40 years old, are recommended to do breast ultrasound while women above 40 are recommended to do mammogram.  From the result of mammogram and ultrasound, if needed, the radiologist will suggest for other modalities as an adjunct to previous modality. 

      Other approved breast cancer prevention is to take tamoxifen.  Tamoxifen is a hormone replacement therapy.  Some or certain patients will be advised by breast surgeon to take it.  Usually women aged 35 years and older shall be at higher risk.  These age group women are those that have already had one breast removed due to cancer, women with a strong family history of breast cancer, and women with genes or genetic mutations that increase their risk potential of breast cancer (breast cancer, 2012).

      Risk factors like genes and family history cannot be controlled.  But we can make a healthy lifestyle changes.  Healthy lifestyle may reduce the overall chance of getting cancer (breast cancer, 2012).  These include eating healthy foods and prevent drinking alcohol and smoking.                     

Unique Features of Mammogram Tube ans X - Ray Spectrum

INTRODUCTION

            Mammography is one of the most demanding radiologic techniques.  It requires an excellent spatial resolution to allow visibility of microcalcifications and good contrast sensitivity to allow detection of breast tumors.   It is difficult to visualize very small physical changes in breasts with general x-ray imaging.  That is why mammography equipment was designed differently from general x-ray.  

UNIQES FEATURES OF MAMMOGRAM TUBE

            Mammography equipment consists of two major components.  They are an x-ray tube and an image receptor.  The x-ray beam originates at the x-ray tube and transmitted through the breast.  A film contained in the image receptor to record the images from x-ray distribution that passed through the breast tissue.

Image receptor

Figure 1. Mammogram Equipment. Reprinted from Screen-film Mammography Equipment Unit 3, by B.A. Barnes & X. Ho, n.d., Retrieved from www.santarosa.edu/.../Unit%203%20-%20Mammography. Reprinted with permission.

           

Features of mammogram x-ray tube that are unique compare to general x-ray tube include x-ray tube anode, target materials, filament design, filter, focal spots, source-to-image distance, and object to image receptor distance.

            Most x-ray tubes use tungsten as the anode material, however mammography equipment uses molybdenum and in some designs, it uses a dual material anode with an additional rhodium track.  Molybdenum and rhodium are used because they produce a characteristic radiation spectrum that is close to optimum for breast imaging (Sprawls, 1995).     

            To reduce unnecessary exposure to the patient, most x-ray machines use aluminum to filter the x-ray beam.  Sprawls (1995) mentioned that mammography uses filters that work on different principle and also used to enhanced contrast sensitivity.  Same as in the anode, molybdenum is the standard filter material.  Some systems allow the operator to select either the molybdenum or rhodium filter to optimize the spectrum for specific breast conditions (Sprawls, 1995).

            There is also exit window filtration (Barnes & Ho, n.d.).  Instead of glass, beryllium is used in dedicated mammography tube housing.  Noted that glass act as a filter when dealing with this soft end of the x-ray spectrum, and it filters out photons that would not provide contrast (Barnes & Ho, n.d.).      

            Mammographic x-ray tubes typically have dual filaments in a focusing cups that produces 0.3 and 0.1 mm nominal focal spot sizes (Barnes & Ho, n.d.).  Meaning x-ray tube for mammography has two selectable focal spots.  The spots are smaller compared to other x-ray procedures because mammogram requires for minimal blurring and good visibility of detail to see the small calcifications.  The smaller of the two spots is generally used for the magnification technique (Sprawls, 1995).  Magnification views use a small magnification table which brings the breast closer to the x-ray source and further away from film plate.  This allows the acquisition of zoomed in images of the region of interest (special mammography views, 2008).   

            Other unique component in mammography tube which is source-to-image distance (SID).  SID is the entire distance of the x-ray beam from the focal spot to the image receptor (Barnes & Ho, n.d.).  The greater the distance the less geometric blurs occur.  This affects the focal spot size which affects the size of the objects being imaged.  The larger the SID the larger the field size.  With larger distance of the source to the image, more beam will be needed to penetrate which then can increased the heel effect (Barnes & Ho, n.d.).

            Other feature is object to image receptor distance (Barnes & Ho, n.d.).  It is the distance of the object (the breast) to the image receptor.  Increase of the object to image receptor distance will increase magnification of an area of breast tissue.  It will increase the resolution and contrast of the breast image (Barnes & Ho, n.d.).

 Figure 2. Principle of Mammogram Tube. Reprinted from Mammography Physics and Technology for Effective Clinical Imaging, by P. Sprawls, 1995, Retrieved from http://www.sprawls.org/resources/MAMMO/mammo02.jpg. Copyright 1995 by Sprawls Educational Foundation. Reprinted with permission.

THE X-RAY SPECTRUM

              The x-ray spectrum depends on the combination of three factors.  First factor is the x-ray tube anode material (molybdenum or rhodium), second is material used for x-ray beam filtration (molybdenum or rhodium), and third is the kV which ranging from 24 kV to 32 kV (Sprawls, 1995). 

            As for x-ray tube anode, most mammogram unit uses molybdenum anodes.  However, in some systems have a dual-track anode that allows radiographer or AEC system to select between molybdenum and   rhodium.

            For x-ray beam filtration, the material used is also molybdenum but in some systems they have an alternative rhodium filter that can be selected.  According to Sprawls (1995) the molybdenum filter only should be used with the molybdenum anode.  However, the rhodium filter can be used in combination with both the molybdenum and rhodium anodes.

Figure 3. Factors Affecting the X-ray Spectrum. Reprinted from Mammography Physics and Technology for Effective Clinical Imaging, by P. Sprawls, 1995, Retrieved from http://www.sprawls.org/resources/MAMMO/mammo18.jpg. Copyright 1995 by Sprawls Educational Foundation. Reprinted with permission.

                         

            In physics, there are two types of x-ray radiation produced when electrons hit the x-ray tube anode.  They are bremsstrahlung and characteristic.  Bremsstrahlung is in the form of a broad continuous photon energy spectrum with a maximum energy determined by the selected kV value (Sprawls, 1995).  Characteristic radiation is produced under certain conditions and is confined to just a few photon energies (Sprawls, 1995).      

            The photon energies of the characteristic radiation are determined by the atomic characteristics of the anode material which varies with the atomic number (Z) of the material.  For mammography, molybdenum and rhodium are materials that produce characteristic x-ray radiation that is near the optimum energy which is why they are used for the anodes (Sprawls, 1995).

            In mammography, the filters used are based on the ‘k-edge’ principle and it attenuates the radiation above the k-edge energy of the specific material (Sprawls, 1995).

Figure 4. K-edge Principle. Reprinted from Mammography Physics and Technology for Effective Clinical Imaging, by P. Sprawls, 1995, Retrieved from http://www.sprawls.org/resources/MAMMO/mammo28.jpg. Copyright 1995 by Sprawls Educational Foundation. Reprinted with permission.

           

            Sprawls (1995) noted that with an atomic number of 42, molybdenum has a k-shell binding energy and its k-edge at energy of 20 keV and rhodium, with an atomic number of 45 also has a k-shell binding energy and its k-edge at energy of 23.22 keV.  When molybdenum filter is selected, it attenuates and blocks much of the bremsstrahlung spectrum above the energy of 20 keV and gives results in the spectrum that is most often used in mammography which is ‘moly/moly’ anode/filter combination (Sprawls, 1995).

Figure 5. The Moly/Moly Spectrum. Reprinted from Mammography Physics and Technology for Effective Clinical Imaging, by P. Sprawls, 1995, Retrieved from http://www.sprawls.org/resources/MAMMO/molymoly.jpg. Copyright 1995 by Sprawls Educational Foundation. Reprinted with permission.

           

            The k edge boundary is shifted to a higher energy with the rhodium filter.  So the portion of the bremsstrahlung between 20 keV and 23.22 keV is added to the x-ray beam.  This makes the beam more penetrating which provides some advantage when taken image of larger or denser breast (Sprawls, 1995).

Figure 6. The Moly/Rhodium Spectrum. Reprinted from Mammography Physics and Technology for Effective Clinical Imaging, by P. Sprawls, 1995, Retrieved from http://www.sprawls.org/resources/MAMMO/molyrho.jpg. Copyright 1995 by Sprawls Educational Foundation. Reprinted with permission.

   

           

            Another anode material is rhodium.  Rhodium can be selected to produce a more penetrating x-ray beam.  Rhodium’s atomic number (Z) is 45 and has principal characteristic radiation at energy of 20.3 keV with a less intense emission at 22.7 keV.  Compare to molybdenum which atomic number (Z) is 42 and principal characteristic energy of 17.6 keV with less intense peak at 19.7 keV (Sprawls, 1995).

            The rhodium filter, with a k-edge cut off at 23.22 keV, is always used with the rhodium anode.  The molybdenum filter cannot be used with rhodium anode because its k-edge cut off from 20 keV upward would attenuate the rhodium 20.3 keV and 22.7 keV radiations (Sprawls, 1995).

Figure 7. The Rhodium/Rhodium Spectrum. Reprinted from Mammography Physics and Technology for Effective Clinical Imaging, by P. Sprawls, 1995, Retrieved from http://www.sprawls.org/resources/MAMMO/rhorho.jpg. Copyright 1995 by Sprawls Educational Foundation. Reprinted with permission.

           

            Third factor that affect the x-ray spectrum is kV.  Increasing the kV has two effects on the x-ray beam.  First, it increases the efficiency and output for a specific mAs value and second it shifts the photon energy spectrum upward so that the beam becomes more penetrating (Sprawls, 1995).  Penetrating beam reduce contrast sensitivity and it is necessary for dense breast.  Therefore compressed breast thickness is the principal factor that determines the optimum kV (Sprawls, 1995).

Figure 8. KV Selection for Different Breast Thickness. Reprinted from Mammography Physics and Technology for Effective Clinical Imaging, by P. Sprawls, 1995, Retrieved from http://www.sprawls.org/resources/MAMMO/mammo32.jpg. Copyright 1995 by Sprawls Educational Foundation. Reprinted with permission.

DISCUSSION

            According to Sprawls (1995) the photon energy spectrum of the x-ray beam is one of the most critical factors in optimizing a procedure with respect to contrast sensitivity and radiation dose.  Although many said that anode materials used in mammogram can only be molybdenum and rhodium, today many researchers do the study on tungsten as an anode material for mammogram tube to see whether it still can produce good contrast and low radiation dose. 

            Between all of the anode materials used in mammography tube, which are molybdenum, rhodium, and specialized tungsten, many researchers agree that molybdenum is the best material to be used because it allows production of low energy spectrums of radiation and only need low kVp which is 26 to 30 kVp (Barnes & Ho, n.d.). 

            However, recently there is study done using tungsten as an anode material with rhodium in mammography and according to researchers, if the molybdenum x-ray tube digital mammography demonstrated a 30 percent reduction in dose, the introduction of tungsten x-ray tubes with digital mammography allows even greater reduction in radiation exposure, without affecting image quality (Smith, Chen, & Semine, 2005).

            Another study done from Dance, Klang, and Sanborg (2000) to compare performance of mammographic x-ray systems that use different anode/filter combinations for screen film and digital imaging.  For screen film mammography, result for thicker breasts shows 20 percent improvement in contrast can be achieved but without reduce radiation dose using molybdenum/rhodium or rhodium/rhodium,  Whereas more than 50 percent of dose saving can be attained but no improvement in contrast using tungsten/rhodium or rhodium/aluminum spectra.  As in digital mammography, Dance et al. (2000) mentioned that molybdenum/molybdenum spectrum delivers the lowest dose for a two centimeter breast, but gives the highest dose for thicker breasts.  However tungsten/rhodium or rhodium/aluminum spectra provide the lowest doses at greater thickness.  Researchers concluded that from this study, molybdenum/molybdenum is the spectrum of choice for all but not for thicker or most glandular breasts.

CONCLUSION

            The most important part of dedicated equipment in mammography is the x-ray tube.  The tube is designed and constructed uniquely and specifically for imaging the soft tissue of the breast.  The x-ray machines used for mammograms today designed to produce lower energy x-rays but improves in image quality and less radiation.   

REFERENCES

Barnes, B.A., (n.d.). Screen-Film Mammography Equipment Unit 3. Retrieved April 27, 2013,     from www.santarosa.edu/

Dance, D.R., Klang, A.T., Sandborg, M., Skinner, C.L., Smith, A.C., & Carlsson, G.A. (2000).    Influence of anode/filter material and tube potential on contrast, signal-to-noise ratio and           average absorbed dose in mammography. The British Journal of Radiology, 73 (2000),            1056-1067. Retrieved from bjr.birjournals.org/content/73/874/1056.full.pdf

Smith, A., Chen, B., & Semine, A. (2005). Minimizing Dose in Digital Mammography.     Retrieved May 02, 2013, from www.hologic.com.data/WP_00005_tungsten

Sprawls, P. (1995). Mammography Physics and Technology for Effective Clinical Imaging.          Retrieved April 28, 2013, from www.sprawls.org/resources/mammo/module.htm

Special Mammographic Views. (2008). Retrieved April 28, 2013, from             www.imaginis.com/mammography/special-mammography-views-spot-c