PARACENTESIS

The removal of fluid from a body cavity via a needle, a trocar, a cannula, or another hollow instrument. A paracentesis may be used for diagnosis or treatment, as, for example, in ascites, where there is free fluid in the abdominal (peritoneal) cavity. If the cause of the

ascites is uncertain, diagnostic paracentesis is done in order to obtain fluid that can be examined. Therapeutic paracentesis may then be done to remove more fluid, as part of the plan

of treatment. Paracentesis of the chest cavity is called a thoracentesis.

Indication

Diagnostic tap is used for the following

New-onset ascites - Fluid evaluation helps to determine etiology, differentiate transudate versus exudate, detect the presence of cancerous cells, or address other considerations

Suspected spontaneous or secondary bacterial peritonitis

Therapeutic tap is used for the following:

Respiratory compromise secondary to ascites

Abdominal pain or pressure secondary to ascites (including abdominal compartment syndrome).

Contra-Indication

Relative contraindications -The benefits of abdominal paracentesis in patients with appropriate indications almost always outweigh the risks. An analysis of the fluid helps

determine the cause(s) of the ascites and the likelihood of bacterial infection, and it can identify antibiotic susceptibility of any organisms that are cultured.

However, there are some relative contraindications to paracentesis

Patients with clinically apparent disseminated intravascular coagulation and oozing from needle sticks. This occurs in <1/1000 patients with ascites in our experience. Paracentesis can be performed once the bleeding risk is reduced by administering platelets and, in some

cases, fresh frozen plasma.

Primary fibrinolysis (which should be suspected in patients with large, three-dimensional bruises). Paracentesis can be performed once the bleeding risk is reduced with treatment.

Paracentesis should not be performed in patients with a massive ileus with bowel distension unless the procedure is image-guided to ensure that the bowel is not entered.

The location of the paracentesis should be modified in patients with surgical scars so that the needle is inserted several centimeters away from the scar. Surgical scars are

associated with tethering of the bowel to the abdominal wall, increasing the risk of bowel perforation.

Blood Works

In patients with new-onset ascites of unknown origin, peritoneal fluid should be sent for cell count, albumin level, culture, total protein, Gram stain, and cytology.

Inspection: Most ascitic fluid is transparent and tinged yellow. A minimum of 10,000 red blood cells/µL is required for ascitic fluid to appear pink, and more than 20,000 red blood

cells/µL will produce distinctly blood-tinged fluid. This may result from either a traumatic tap or malignancy. Bloody fluid from a traumatic tap is heterogeneously bloody, and the fluid will clot.

Nontraumatic bloody fluid is homogeneously red and does not clot because the blood has already clotted and lysed. Cloudy ascitic fluid with a purulent consistency indicates infection.

Cell count: Normal ascitic fluid contains fewer than 500 leukocytes/µL and fewer than 250 polymorphonuclear leukocytes (PMNs)/µL. Any inflammatory condition can cause an elevated

white blood cell count. A PMN count of greater than 250 cells/µL is highly suggestive of bacterial peritonitis. In tuberculous peritonitis and peritoneal carcinomatosis, lymphocytes

usually predominate.

SAAG: The SAAG is the best single test for classifying ascites into portal hypertensive (SAAG >1.1 g/dL) and non–portal hypertensive (SAAG < 1.1 g/dL) causes. Calculated by

subtracting the ascitic fluid albumin value from the serum albumin value, it correlates directly with portal pressure. The specimens should be obtained relatively simultaneously. The

accuracy of the SAAG results is approximately 97% in classifying ascites. The terms high-albumin gradient and low-albumin gradient should replace the terms transudative and

exudative in the description of ascites.

Total protein: In the past, ascitic fluid has been classified as an exudate if the protein level is greater than or equal to 2.5 g/dL. However, the accuracy is only approximately 56% for

detecting exudative causes. The total protein level may provide additional clues when used with the SAAG. An elevated SAAG and a high protein level are observed in most cases of

ascites due to hepatic congestion. The combination of a low SAAG and a high protein level is characteristic of malignant ascites (see Causes).

Culture/Gram stain: Culture has a 92% sensitivity for the detection of bacteria in ascitic fluid, provided that samples are inoculated into blood culture bottles immediately, at the bedside. In contrast, Gram stain is only 10% sensitive for visualizing bacteria in early-detected spontaneous bacterial peritonitis. Approximately 10,000 bacteria/mL are required for detection by Gram stain; the median concentration of bacteria in spontaneous bacterial peritonitis is 1

organism/mL.Cytology: Cytology smears are reported to be 58-75% sensitive for detection of malignant

ascites.

Imaging Modality Use

Endoscopic ultrasound and paracentesis in the evaluation of small volume ascites in patients with intra-abdominal malignancies.

The evaluation of ascites in patients with known or suspected malignancy is a critical aspect of preoperative staging. Endoscopic evaluation by ultrasound of low volume ascites and sampling of the ascitic fluid by endoscopic ultrasound guided paracentesis (EUS-P) is

both a sensitive and specific modality for the determination of peritoneal implants, which is not only an important prognostic indicator but a crucial factor in determining treatment strategy. It

is common practice to utilize EUS for gastrointestinal malignancies such as pancreatic or gastric masses, with the performance of paracentesis during the same procedure for the

purpose of imaging the abnormality and possibly performing fine needle aspiration for biopsy of the neoplasm itself. However, given the ability of EUS-P to adequately sample even minimal

ascites, detecting much smaller volumes than traditional computed tomography or magnetic resonance imaging, EUS-P may be a useful modality for the standard metastatic workup of

any newly diagnosed or suspected malignancy. In this "Field of Vision" commentary, we discuss the role of EUS-P, including the article by Suzuki et al reporting their experience with EUS-P using an automated spring-loaded needle device. We also review the utility of EUS-P for non-gastrointestinal malignancies, such as ovarian cancer, which has a high incidence of

malignant ascites.

Instrument Use

Our Thora-Para catheter drainage system offers time-tested features you need for safe and efficient diagnostic and therapeutic procedures.

Available in 8 Fr or 5 Fr sizes, the device includes a 4 ¾” polyurethane catheter over an 18G x 8˝ introducer needle to provide a safe, strong, supple fluid path for excellent specimen retrieval

and therapeutic drainage.

The Thora-Para device also maintains a closed system with a self-sealing valve that is activated automatically upon removal of the introducer needle. Catheters with multiple spirally

oriented fenestrations reduce the chance of obstruction, helping ensure optimum return of fluid. Our tray configurations include convenient universal drainage sets with one-way fluid valves and

secure luer lock connections, as well as a drainage tube and a 15G vacuum needle.

This device is offered in a variety of convenient procedure trays, including Safe-T™ PLUS trays, which provide components for sharps safety and preventable medical error reduction and

are designed to help you comply with today’s safety recommendations.

THORACENTESIS

Thoracentesis is a procedure to remove fluid from the space between the lungs and the chest wall called the pleural space. It is done with a needle  (and sometimes a plastic catheter)

inserted through the chest wall. Ultrasound pictures are often used to guide the placement of the needle. This pleural fluid may be sent to a lab to determine what may be causing the fluid to

build up in the pleural space.

Normally only a small amount of pleural fluid is present in the pleural space. A buildup of excess

pleural fluid (pleural effusion ) may be caused by many conditions, such as infection,

inflammation, heart failure, or cancer. If a large amount of fluid is present, it may be hard to

breathe. Fluid inside the pleural space may be found during a physical examination and is

usually confirmed by a chest X-ray.

Indication

This procedure is indicated when unexplained fluid accumulates in the chest cavity

outside the lung. In more than 90% of cases analysis of pleural fluid yields clinically useful

information. If a large amount of fluid is present, then this procedure can also be used

therapeutically to remove that fluid and improve patient comfort and lung function.

The most common causes of pleural effusions are cancer, congestive heart

failure, pneumonia, and recent surgery. In countries where tuberculosis is common, this is also

a common cause of pleural effusions.

When cardiopulmonary status is compromised (i.e. when the fluid or air has its

repercussions on the function of heart and lungs), due to air (significant pneumothorax), fluid

(pleural fluid) or blood(hemothorax) outside the lung, then this procedure is usually replaced

with tube thoracostomy, the placement of a large tube in the pleural space.

Contra-indication

An uncooperative patient or a coagulation disorder that cannot be corrected are relative

contraindications. Relative contraindications include cases in which the site of insertion has

known bullous disease (e.g. emphysema), use of positive end-expiratory pressure (PEEP,

see mechanical ventilation) and only one functioning lung (due to diminished reserve). The

aspiration should not exceed 1L as there is a risk of development of pulmonary edema.

Blood Works

A diagnostic thoracentesis involves the removal of fluid for analysis (pleural fluid analysis). In general, pleural fluid is classified as exudate (seen in inflammatory, cancerous, or

infectious conditions) or transudate (fluid that has leaked from blood or lymph vessels for various reasons, such as congestive heart failure). Pleural fluid analysis may help to confirm or

rule out infections or diseases such as cancer, congestive heart failure, liver failure, or pulmonary hypertension (high pressure in the lungs' blood vessels). Therapeutic thoracentesis

may help to relieve discomfort from shortness of breath because of a pleural effusion.

Other related procedures that may be used to diagnose problems with the lungs and respiratory tract include bronchoscopy, computed tomography (CT scan) or magnetic resonance

imaging (MRI) of the chest, chest X-ray, chest ultrasound, and oximetry. Please see these procedures for additional information.

Imaging Modality Use

The diagnostic evaluation and imaging of a pleural effusion and the technique of diagnostic thoracentesis.

Advantages - Thoracic ultrasound has several advantages over traditional radiographic imaging of the pleura, including absence of radiation, better portability, real-time imaging, and

the ability to perform dynamic imaging.

Ultrasound is substantially better at determining the location of pleural fluid than bedside physical examination and, in experienced hands, is associated with a lower rate of

complications during thoracentesis. In addition, ultrasound guidance increases the likelihood of a successful tap compared to using physical examination for guidance. As an example, in a

study of 17 patients who had a failed thoracentesis without ultrasound imaging, thoracentesis with ultrasound was successful in 15. Ultrasound examination of the pleura is more sensitive

than a plain chest radiograph at detecting the presence of pleural fluid and differentiating pleural fluid from lung consolidation. Compared with computed tomography (CT), pleural ultrasound

has a 95 percent sensitivity for detection of pleural disease in patients with a “white out” on plain chest radiograph, but is slightly less sensitive in detecting small amounts of fluid. Compared

with CT scanning, ultrasound may better differentiate pleural fluid from pleural thickening and pleural masses. Bedside thoracic ultrasound is also faster and less resource-demanding than

transporting a critically-ill patient to the CT scanner.

Ultrasound guidance is associated with a reduced risk of pneumothorax during thoracentesis. In an observational cohort study of insurance database claims for 61,261 thoracenteses,

ultrasound guidance was associated with a reduced likelihood of pneumothorax (OR, 0.81; 95% CI, 0.74-0.90).

Disadvantages -Thoracic ultrasound is an operator dependent technology. Focused, supervised training is needed to ensure that the operator correctly interprets the sonographic

findings. Inadequate training may increase the risk of complications.

Ultrasound is not as good as CT imaging for evaluation of the underlying lung parenchyma in the setting of complex pleural and lung parenchymal disease. Ultrasound guidance is not as

good as guidance by CT imaging for complicated interventional procedures, such as empyema drainage with a pigtail catheter or biopsy of pleural masses.

Instrument Use

Sterile thoracentesis tray:

Calibrated drainage bottle.

Sterile gloves.

4x4 gauze compresses.

Prescribed local anesthetic.

Alcohol prep sponges.

Adhesive tape.

Mobile table or stand.

Waste receptacle.

PICC LINE (Peripherally Inserted Central Catheter)

The veins in your arms are called peripheral veins. That simply means they're not in the center part of your body. A catheter inserted into a peripheral vein and guided to a central vein

is called a peripherally inserted central catheter. It's also called a PICC line. PICC line placement involves inserting a PICC line into a large blood vessel that leads to your heart.

Indications

PICCs may be used for any infusate, regardless of osmolarity, pH, or other chemical

properties of the solution or medication. With central tip termination, the blood flow around the

catheter is high, usually 2 L or more per minute. This provides immediate dilution of the infusate

and helps protect the vessel walls from chemical irritation by the prescribed therapy. Many

intravenous medications and solutions cause damage to the peripheral venous endothelium and

should be administered centrally to avoid this damage.

A PICC is often the central VAD of choice, due to the lower incidence of infection

compared with subclavian and internal jugular percutaneous catheters, and because there is no

risk of pneumothorax with the PICC insertion procedure. The documented infection rate for

PICCs is 0.75 infections per 1000 catheter days, compared with short-term (nonmedicated)

central venous catheters at 2.51 infections per 1000 catheter days. PICCs are also indicated for

short-term infusions for patients with limited venous access and for therapies that will continue

over long periods of time.

Contraindication

Several factors contraindicate PICC placement: lack of peripheral access, venous thrombosis,

and end-stage renal disease. In addition, PICCs should not be used for frequent intermittent

access or for blood sampling.

Patients with restricted peripheral access must be sent to the interventional radiology

department to have PICC placement performed under fluoroscopy. These patients also may be

referred to a facility that uses the modified-Seldinger technique with ultrasound for bedside

PICC placement. Sometimes, a patient may not have an accessible peripheral vein, even when

ultrasound is used. This patient will require a different type of central catheter.The presence of

upper extremity or subclavian thrombosis is another contraindication for bedside PICC insertion,

whether or not ultrasound is used. These patients also may be referred to interventional

radiology to have a PICC inserted under fluoroscopy.

Patients with chronic renal failure and end-stage renal disease are not appropriate

candidates for PICC placement. The need to preserve peripheral veins for future dialysis fistulas

is a critical issue for these patients. Insertion of any catheter in the upper extremity or the

subclavian veins can cause thrombus formation and scarring that could reduce the probability

for successful fistula development. The internal jugular vein, particularly the right jugular vein, is

the preferred insertion site for these patients. Although this choice is not without risks, it

provides the straightest and shortest route to the superior vena cava and minimizes potential

venous damage.

Insertion of any central VAD must be performed judiciously, as every insertion increases

the risk of vessel damage, thrombosis, and stenosis, and potentially creates difficulty in

obtaining future access. PICC insertion often becomes difficult or impossible for patients who

have had multiple previous PICCs. If a patient requires frequent intermittent access, an

implanted venous port may be a better choice.

Because a PICC is very long and thin, it is not advisable to insert it solely for the purpose

of obtaining blood for laboratory analysis. Each blood draw increases the risk of occluding the

catheter. A risk-benefit analysis should be done to determine the value of using a PICC for

drawing blood. Manufacturers' directions for use should be consulted carefully when making this

decision.

Blood Works

A PICC line is a long, thin, hollow tube that a doctor or nurse puts into a vein above the bend of your elbow. It is used to give you chemotherapy and other medicines. It can stay in place until

your treatment is over.

You’ll be given a local anaesthetic to numb the area before the line is put in.

Your doctor or nurse will gently thread the line along the vein in your arm until it’s in a large vein in your chest.  You’ll have an x-ray to check it’s in the correct position.

The PICC line is held in place by a dressing which is changed every week. The cap at the end of the line is replaced weekly to reduce the risk of infection. The line is flushed regularly to

prevent it becoming blocked.

Contact your hospital doctor or nurse if you have any swelling, pain, leaking fluid around the PICC line, or if you don’t feel well. These may be symptoms of an infection or blood clot.

Once you no longer need the PICC line, it will be removed.

Imaging Modality Use

Interventional Radiology

Interventional radiology is the use of image-guided techniques to perform a variety of minimally invasive procedures and treatments through small catheters. Interventional radiology services

include:

Cryoablation: This process uses extreme cold to destroy or damage tissue.

Radiofrequency (RF) ablation: This procedure uses electrical current to destroy or damage tissue.

Uterine fibroid embolization (UFE): This procedure is performed to treat fibroids, noncancerous growths in or on the uterus, by blocking blood flow to the fibroids.

Image-guided biopsy: A biopsy is the removal of a sample of tissue or fluid from the body for examination under a microscope. Image-guided biopsy is the use of imaging modalities,

such as ultrasound or MRI, to precisely locate the targeted tissue or fluid.

Vascular procedures

PICC placement: Peripherally inserted central catheter (PICC) is a form of intravenous (IV) therapy used for chemotherapy, antibiotic therapy or total parenteral nutrition.

Imaging modalities can be used to help accurately place the PICC line.

Port placement: A port is a device implanted under the skin of the chest that enables medication to be delivered into the veins and enables blood samples to be taken from

the veins. Imaging modalities can be used to help accurately place the port.

Angioplasty: Under the guidance of a imaging modality, an empty, collapsed balloon is inserted into a narrowed or obstructed artery and inflated to widen the artery. A stent

may also be inserted to help keep the artery open.

Instrument Use

Central linesThe other way of giving intravenous chemotherapy is through a long, flexible, plastic line

called a central line. These are called central lines because they end up in a central blood vessel in your chest, close to your heart. There are different types.

One type of line goes in through a vein in your neck. This is called an acute central line and is used for short term treatments.

Another type of line goes in through your chest, then it is tunnelled under your skin to a large vein by your collarbone. The only bit you can see is the length of line that hangs out of the small

entry hole in your chest.

At the end of the length of line that you can see there are connection ports where your chemotherapy drug is attached. The connection ports are kept closed with caps. This is a

picture of a central line in place.

Other central lines you may hear about are PICC lines and portacaths.

The central line can stay in your vein for many months. So you won't need to have needles into your hand or arm each time you have your chemotherapy treatment. You can move about

normally, it won't come out while you are sleeping or dressing for example. This is because there is a small cuff on the line, which is under the skin and holds it in place.

You have a general or local anaesthetic before the central line is put in. When it's in place, the central line is stitched in place or special dressings may be put over it so that it can't come out. Your doctor may want you to have an X-ray afterwards to make absolutely sure the end of the

tube is in the best place. Sometimes the tube is put in using continuous X-rays, so that the doctors can see where the tube is going.

Your doctor and nurse can also take blood from the line for tests. They can also use the line to give you fluids or other treatment such as antibiotics if these are needed.

The video below shows how a tunnelled central line is put in. Click on the arrow to watch it.

Portacaths

A portacath is a small chamber or reservoir that sits under your skin at the end of your central line. The other end of the line sits in a large vein close to your heart. You can feel the chamber of the portacath, but unless you are very thin you cannot usually see it. When you

need treatment, your chemotherapy nurse puts a needle into the chamber and gives you injections or attaches a drip. The drugs travel from the chamber to the tubing and into your

bloodstream. The portacath stays in place for as long as you need treatment.

The main advantage of a portacath is that you can't see it on the outside of your body. You don't have a tube coming out of your chest as you do with a central line. But some people prefer a

central line because they don't like having a needle put in each time they need treatment. If you prefer, you can have the area over the portacath numbed with a local anaesthetic cream before

the needle is put in.

PICC linesPICC stands for Peripherally Inserted Central Catheter. This is a type of central line. It is put into

a vein in your arm, under local anaesthetic. It can be put in during an outpatient appointment. The line runs up the vein, inside your arm and ends up in a large vein in your chest. PICC lines

can be left in for several months and used in a similar way to other central lines.

Possible problems with intravenous lines

Sometimes problems occur with the line

You may get an infectionThe line may get blockedA blood clot can develop

A PICC line may split, but this is very rare

The line is flushed regularly with heparin (an anti clotting drug) or salt water (saline) to prevent clotting. The nurses on the ward can teach you how to do this. Your district nurse can help you at home at first. Occasionally, your doctor may also prescribe treatment with a low dose of the

drug warfarin. Warfarin is a commonly used drug.

It is very important to avoid getting an infection in the area where your line goes into your body. Phone the hospital and speak to your chemotherapy nurse or doctor if you notice any

Redness Swelling Soreness

These could be signs of infection. You will need to have treatment with antibiotics straight away if you do develop an infection. Otherwise, the line may have to be removed and a new one put

in.

If you are not having treatment regularly you or a nurse need to clean and flush the line regularly to keep it clear and stop you developing any problems.

Your everyday life

You can go home with a central line in place. It is okay to have a bath or shower. There are very

few restrictions to your everyday life. If you have a PICC line, there are waterproof covers

available for your arm. You shouldn't allow your PICC line to go under water in the bath, unless

you have awaterproof cover. These covers are good enough to use for swimming, although it is

important that you check with your doctor first if you are having chemotherapy. There may be an

infection risk from using a public pool.

Before you go home make sure you are confident about looking after your line. Ask the staff on

the ward if you are not sure about anything. They can arrange for district nurses to visit you at

home to help with the line until you feel confident about looking after it.

If you have problems at home contact the medical staff on the ward or chemotherapy day unit

for advice.

College of Radiologic TechnologyInterventional Radiology

AY: 2014-2015(Finals)

Sub. By:

Karl Angelo C. Aquino

(12-00085)

Sub. To:

Ma’am Karen Harder

College of Radiologic Technology

Interventional Radiology

AY: 2014-2015(Finals)

Sub. By:

Karl Angelo C. Aquino

(12-00085)

Sub. To:

` Ma’am Karen Harder

College of Radiologic Technology

Radiation Theraphy

AY: 2014-2015(Finals)

Sub. By:

Karl Angelo C. Aquino

(12-00085)

Sub. To:

Ma’am Karen Harder

Respiratory Gating in Radiotherapy

Respiratory gating is a process for continuously monitoring the movement of tumors during normal breathing. Radiation is only delivered when the tumor is exactly in the right place, and the treatment beam automatically turns off when the tumor moves outside of the target field. This technique is used as part of some radiation therapy treatment plans.

Stereostactic radiosurgery (SRS)

Stereotactic radiosurgery (SRS) is a form of radiation therapy that focuses high-power energy on a small area of the body. Despite its name, radiosurgery is a treatment, not a surgical

procedure. Incisions (cuts) are not made on your body.

Stereotactic Treat Select Primary Tumors

These techniques are used to directly treat selected primary tumors of the brain and the skull base, such as meningiomas and vestibular schwannomas, many metastatic lesions of the brain,

as well as, other conditions such as, arteriovenous malformations (AVM).

Stereotactic Therapy Candidates

Patients receiving stereotactic therapy can be treated for one or more lesions simultaneously. Ideally the lesions should be 5 cm in size or smaller. Each patient’s situation

can vary and therefore, referring physician consultation with the radiation oncologist is necessary. 

Recovery Time

Most patients resume normal daily activities, such as work or school, within two to three days. Patients are usually discharged home within hours after receiving stereotactic

radiosurgery or radiotherapy. However, if medically necessary, patients may be required to stay in the hospital over night for observation. 

Fractionated Stereotactic Radiotherapy (FSR)

To evaluate the toxicity and efficacy of fractionated stereotactic radiotherapy (FSRT) with doses of 18–30 Gy in three fractions and 21–35 Gy in five fractions against large brain metastases.

Materials and methods

Between 2005 and 2012, 61 large brain metastases (≥2.5 cm in maximum diameter) of a total of

102 in 54 patients were treated with FSRT as a first-line therapy. Neurological symptoms were

observed in 47 of the 54 patients before FSRT. Three fractions were applied to tumours with a

maximum diameter ≥2.5 cm and <4 cm, and five fractions were used for brain metastases

≥4 cm. After ensuring that the toxicities were acceptable (≤grade 2), doses were escalated in

steps. Doses to the large brain metastases were as follows: level I, 18–22 Gy/three fractions or

21–25 Gy/five fractions; level II, 22–27 Gy/three fractions or 25–31 Gy/five fractions; level III,

27–30 Gy/three fractions or 31–35 Gy/five fractions. Level III was the target dose level.

Results

Overall survival rates were 52 and 31% at 6 and 12 months, respectively. Local tumour control

rates of the 102 total brain metastases were 84 and 78% at 6 and 12 months, respectively.

Local tumour control rates of the 61 large brain metastases were 77 and 69% at 6 and 12

months, respectively. Grade 3 or higher toxicities were not observed.

Types of brain tumours suitable for Fractionated Stereotactic Radiotherapy include:

Benign: Malignant:

Meningiomas Gliomas

Pituitary tumours Medulloblastomas

Vestibular Schwannomas/Acoustic Neuromas Chordomas

Craniopharyngiomas

Haemangiomas

Treatment use

Treatment usually commences approximately one week after planning. When arriving the first day for treatment, please notify the radiation reception staff of your arrival and you will be escorted to the Treatment Area. When the radiotherapists are ready you will be called into

the treatment room where the head frame is fitted daily prior to each treatment. At the conclusion of each treatment the following day's treatment time will be confirmed with you (this

occasionally may change).

Multi-leaf collimator (MLC)

A multileaf collimator (MLC) is a device made up of individual "leaves" of a high atomic

numbered material, usually tungsten, that can move independently in and out of the path of

a particle beam in order to block it.

MLCs are used on linear accelerators to provide conformal shaping of radiotherapy treatment

beams. Specifically, conformal radiotherapy and Intensity Modulated Radiation Therapy (IMRT)

can be delivered using MLC's.

The MLC has improved rapidly since its inception and the first use of leaves to shape structures

in 1965 to modern day operation and use. MLC's are now widely used and have become an

integral part of any radiotherapy department. MLC's were primarily used for conformal

radiotherapy, and have allowed the cost effective implementation of conformal treatment with

significant time saving, and also have been adapted for use for IMRT treatments. For conformal

radiotherapy the MLC allows conformal shaping of the linear accelerator (LINAC) beam to

match the borders of the target tumour. For intensity modulated treatments the leaves of a MLC

can be moved across the field to create IMRT distributions (MLC's really provide

a fluence modulation rather than intensity modulation).

The MLC is an important tool for radiation therapy dose delivery. It was originally used as a

surrogate for alloy block field shaping and is now widely used for IMRT. As with any tool used in

radiotherapy the MLC must undergo commissioning and quality assurance. Additional

commissioning measurements are completed to model a MLC for treatment planning. Various

MLC's are provided by different vendors and they all have unique design features as

determined by specifications of design, and these differences are quite significant.

Stereotactic Body radiation Therapy (SBRT)

Stereotactic body radiation therapy (SBRT), also called stereotactic ablative radiotherapy (SABR), is a type of radiation therapy in which a few very high doses of radiation are delivered to small, well-defined tumors. The goal is to deliver a radiation dose that is high

enough to kill the cancer while minimizing exposure to surrounding healthy organs.

MD Anderson's stereotactic body radiation treatment suite. 

SBRT is typically used to treat small, early-stage tumors of the lung, or isolated recurrences or metastases from various types of cancer. SBRT has also been used successfully

to treat early-stage non-small cell lung cancer, recurrent lung parenchyma cancer, pancreatic cancer, and metastatic cancers in the:

Lung Liver

Adrenal glands Spine

SBRT is being tested at MD Anderson to treat other types of cancer. In some cases, it can be used instead of surgery.

SBRT begins with one or more sessions of treatment planning, which involves using imaging (computerized tomography, magnetic resonance imaging, positron emission tomography

scanning and X-rays) to precisely map the exact position of the tumor to be treated. These images are then used to create customized treatment plans in which sophisticated

computerized devices direct several radiation beams of different intensities at different angles, so that the radiation is directed precisely to the tumor.

Treatments are usually given once a day for about a week, although this can vary depending on the type of tumor and the condition of the patient. Other images are also taken during the treatment period to account for shrinkage of the tumor or other changes that might

affect its position.

Stereotactic body radiation therapy is not appropriate for everyone. The most important considerations are the type of cancer and where it is located, as well as the physical condition of

the patient. Meticulous treatment planning and image-guided treatment delivery are crucial for the success of SBRT and for keeping side effects to the lowest possible level. Your radiation oncologist will discuss whether SBRT is suitable for you and what kinds of side effects may

result from your treatment.