Sunday, February 3, 2008

Gleneagles Hospital



Gleneagles Hospital is established as a leading centre for the care and treatment

of cardiac patients. The highly skilled nursing team, together with the experience

and expertise of the physicians and surgeons, continually advance the standards of

Gleneagles’ cardiac care.

Cardiac care is one of the cornerstones of Mount Elizabeth Hospital’s sterling

reputation as a leading private healthcare facility of choice. The first open-heart

surgery in private practice in Singapore was performed in Mount Elizabeth. The

Hospital has always maintained her cutting-edge lead in the disciplines of cardiology

and cardiothoracic surgery.




Coronary Heart Diseases Prevention and Treatment Services






Coronary heart disease is one of the top killers in Asia and in many developed

countries throughout the world. Parkway Group Healthcare, which owns East Shore,

Gleneagles and Mount Elizabeth hospitals in Singapore, and seven hospitals in

the region, is the largest private healthcare organisation in Asia. It is committed to

providing comprehensive and quality care to the prevention and treatment of coronary

heart diseases.

With more than 30 cardiologists and cardiothoracic surgeons, our depth and breadth

of medical, clinical and surgical experience is focused on giving cardiac patients the

latest treatment options, supported by investment in state-of-the-art technology

and equipment.

With the largest concentration of cardiac specialist physicians under one roof, as well

as qualified and compassionate nursing care, Parkway Group Healthcare is the ideal

choice for patients with cardiac conditions.

Chest X-ray

Cardiac Calcium Scoring

Electrocardiogram (ECG)

SCREENING PROCEDURES



CHEST X-RAY

Although considered a basic and routine investigation, a simple chest x-ray provides valuable information

on the general condition of the patient’s heart as well as the thoracic cavity.

The chest x-ray can indicate the size and position of the heart, any gross abnormalities and changes in the

heart size, which can serve as a primary indicator of heart failure or obvious congenital abnormalities.

The lung fields can indicate changes occurring as a result of heart failure such as collections of fluids in

addition to any lung pathology that might be evident.

As a basic screening procedure, the chest x-ray helps a clinician to detect signs indicative of a heart

condition and also serve as a useful guide in pursuing more sophisticated means of investigations to ascertain

the patient’s health status.

Even if no gross abnormalities are detected, the captured ‘image’ serves as a very reliable base line, which

can be archived for future reference.

Chest X-ray

An ECG is quick, safe and

painless. The process takes

about five to ten minutes.

Cardiac calcium scoring

is a test to detect the presence

of calcium deposits in the arteries.

If calcium deposits are present,

it is an indication of a hardening

of the arteries.



SCREENING PROCEDURES

CARDIAC CALCIUM SCORING

ELECTROCARDIOGRAM (ECG)

Electrocardiogram (ECG)

An Electrocardiogram (ECG) is a recording of the heart’s electrical activity as a graph or a series of wave

lines on a moving strip of paper or video monitor. In this way, one is able to evaluate the heart’s rate, rhythm

and detect the presence of cardiac problems.

The highly sensitive ECG machine helps to detect various heart irregularities, disease and damage.

An ECG is routinely used when heart disease or damage is suspected in a patient who may be experiencing

symptoms such as angina (chest pain), palpitations, shortness of breath, lightheadedness or loss

of consciousness.

How is an ECG performed?

An ECG is quick, safe and painless. It is non-invasive. The patient has to remove his clothes from the

waist up and is then asked to lie down comfortably. The nurse or technician will thoroughly clean a total

of ten areas on the patient’s chest, arms and legs, over which will be attached ten small metal devices

(electrodes). These will be connected by wires to the ECG recorder.

The patient needs to lie still for about one minute while the heart activity is measured and recorded.

Each electrode produces a ‘tracing’ of a particular area of the heart. The entire ECG takes about five to

ten minutes.

Cardiac calcium scoring is a screening procedure

to detect calcium build-up in the coronary arteries.

The test is non-invasive and can be performed in

approximately ten minutes and is completely painless.

Coronary artery calcium is a definite marker for the

presence of artheroscleroris, i.e. the hardening of

the arteries. The results of this screening test allows

the physician to make accurate clinical decisions in

the treatment of coronary artery disease, taking into

consideration the number of calcified vessels, the

patient’s age, gender, symptoms and risk factors.

The calcium scoring chart ranges from zero to over

400. The ‘normal’ score for any age is ideally zero.

The calcium score has greater significance if it

exceeds the 75th percentile of the patient’s age and

sex group, or if calcium is detected in more than two

blood vessels.

Cardiac Calcium Scoring

Stress Test (exercise or pharmalogical)

Nuclear Perfusion Test (exercise or pharmalogical)

Transthoracic Echocardiography (TTE)

Transoesophageal Echocardiography (TEE)

Holter Monitoring

Ambulatory Blood Pressure





DIAGNOSTIC (NON-INVASIVE) PROCEDURES

STRESS TEST

How is an exercise stress test performed?

An exercise stress test requires a patient use a standard treadmill while the ECG electrodes are attached

to the body.

The test requires two phases: the resting phase and the exercise phase.

During the resting phase, the patient lies still while the ECG is taken.

During the exercise phase, the exercise begins at a slow rate and progressively increases his speed

and incline, while the patient’s ECG is recorded periodically, until the patient’s maximum heart rate is

reach when the patient signals discomfort.

Stress Test (Exercise or Pharmalogical)

A stress test is a diagnostic test that allows the physician to understand a patient’s heart activities both at

rest and with exertion.

The stress test can be administered in two ways:

a. through physical exercise,

b. through the administration of medications, to simulate the ‘stress’, or pharmalogical stress test

All stress tests are performed with ECG electrodes attached to the body to monitor the heart’s activity and

allows the physician to compare the ECG patterns at rest and during stress.

Results of a Nuclear Perfusion Scan





NUCLEAR PERFUSION TEST

Nuclear Perfusion Scan (Exercise or Pharmalogical)

A nuclear perfusion scan is similar to the stress test, which requires two phases – resting and exertion.

The nuclear perfusion scan adds another diagnostic tool for the physician: allowing him to determine the

perfusion (blood flow) to the heart muscle. It is similar to the stress test and requires both resting as well

as stress phases. The images are produced by injecting a small amount of radioactive but harmless substance

(tracer) into a vein at the peak of exercise.

A second injection of the tracer is injected for the resting phase of the test, and further images will be taken

with the gamma camera. This tracer is detected by the gamma camera as it flows through the blood vessel

to the heart muscle. It can show where blood flow has been reduced or restricted.

The physician will compare the results of the heart’s activity at resting phase and at exertion phase.

The nuclear perfusion

test measures how the

heart is performing at rest

and during exertion, with

the help of radioactive

elements seen through

a device called a

gamma camera.

Patient undergoing an ‘echo’





TRANSTHORACIC ECHOCARDIOGRAM (TTE)

Transthoracic Echocardiogram (TTE)

Also known simply as an ‘echo’, an echocardiogram is a painless test that uses high-frequency sound waves

(ultrasound) to obtain images of the heart and its various structures.

Echocardiograms are used to evaluate the structure and function of the heart, including:

a. Status of the heart valves

b. Status and strength of the heart muscle

c. Identifying the presence of blood clots or growths within the heart chambers

d. Detecting the causes of abnormal heart sounds (murmurs)

Because the test does not involve any of the radiation that an x-ray does, it is a very safe test. The sound

waves bounce back from the various components of the heart, producing images and sounds that can be

used by the physician to detect any abnormalities.

How is a TTE performed?

The physician prepares the chest area by applying a conductive, water-soluble gel. A small device, the

‘transducer’ is then placed on the patient’s chest, and this is rotated and positioned at various angles

to obtain images of the heart, which can be seen on a video monitor.

The TTE can be used in conjunction with various forms of stress to detect the presence of coronary

artery disease.

a. an exercise, or stress echocardiogram

b. pharmalogical, or drug-enhanced, stress echocardiogram

There may be cases when a patient cannot perform the exercise necessary to an exercise-based

stress test.

In these instances, the physician can still examine the heart by simulating the effects of stress and

exertion by an injection of medication, such as dobutamine. These chemicals stimulate the heart and

mimic the effects of vigorous physical activity.

How is a chemical or pharmalogical stress test performed?

A Holter monitor being attached onto a patient





TRANSOESOPHAGEAL ECHOCARDIOGRAM (TEE)

HOLTER MONITORING

AMBULATORY BLOOD PRESSURE MONITORING (ABPM)

Transoesophageal Echocardiogram (TEE)

This is a form of echocardiogram that involves inserting a transducer down the patient’s throat into the

oesophagus (the long tube that connects the throat with the stomach).

Because the oesophagus is located closely behind the heart, clearer images of the heart structures and

valves can be obtained from inside the body instead of the outside.

A Holter monitor is a portable device that continually monitors the electrical activity of an ambulatory (freelymoving)

patient’s heart over a period of time.

The physician will recommend this test most often when it is suspected that the patient experiences abnormal

heart rhythm, i.e., arrhythmia, or that the patient experiences times when the heart is not getting enough

oxygen-rich blood, i.e., cardiac ischemia.

Ambulatory Blood Pressure Monitoring (ABPM) is a method of measuring blood pressure readings of a

patient over a 24-hour period. A special blood pressure monitor is used, and the patient is asked to keep a

diary of his activities during the monitoring period.

Holter Monitoring

How is Holter monitoring performed?

Wires (electrodes) from the Holter monitor are taped to carefully-prepared areas of the patient’s body.

The patient is sent home to go about his daily activities (except bathing and showering) and the patient

is asked to keep a diary of his activities and any symptoms he may experience.

Ambulatory Blood Pressure Monitoring

Coronary Angiogram





CORONARY ANGIOGRAM

Coronary Angiogram

A coronary angiogram is a x-ray procedure to detect the presence of blockages within the coronary arteries.

These blockages are usually the result of the progressive build-up of materials within the walls of the blood

vessels that lead to the development of coronary heart disease.

How is a coronary angiogram performed?

The physician will inject a special dye into the

coronary arteries. A thin tube (catheter) is

inserted through a blood vessel, usually in the

upper thigh. This catheter is then carefully

manipulated through the patient’s main artery

(the aorta) until it is positioned at the opening of

the coronary arteries.

Once the catheter is in place, a special dye is

injected through the catheter and into the arteries.

Then the x-ray is taken. X-ray pictures are taken

while the dye is being injected to obtain images,

showing the coronary arteries and the presence

or absence of any blockages within them.

The patient is usually given a mild sedative before

the procedure but is aware of his surroundings

throughout the procedure.

A coronary angiogram is the most accurate test

in the diagnosis of coronary artery disease.

Depending on what the angiogram shows, the

physician will recommend treatments such as

medication, interventional (non-surgical)

procedures such as balloon angioplasty, or

bypass surgery.

Biventricular Pacemaker

Percutaneous Transluminal Coronary Angioplasty (PTCA)/Balloon Angioplasty/Stenting

Ablation

Transcatheter Closure of ASD





BIVENTRICULAR PACEMAKER

A pacemaker

regulates the pumping

action of the heart,

when it cannot do so

on its own.

Biventricular Pacemaker

In many heart failure patients, the walls of the left ventricle - the heart’s main pumping chamber - are no

longer synchronised, or pumping together as they normally would. A biventricular pacemaker is designed

to resynchronise the pumping action of the heart.

How is a biventricular pacemaker insertion performed?

After a local anaesthesia is applied, a small

incision is made in the chest wall just above the

collarbone. Another cut is made in the vein just

under the collarbone.

One of the two wires is threaded through the

vein and positioned in a vein that drains the left

ventricle.

The second wire is threaded through the vein

and embedded into the right ventricle.

The wires are secured by tiny screws which

ensure that the electrode at the tip of each wire

is in direct contact with the inner surface of the

heart chamber. The other ends of the wires are

connected to a generator, which is inserted into

the tissue under the collarbone. The incision is

then closed.

The procedure may take one to two hours, and

can be performed as an inpatient or outpatient

procedure.

Aorta

Left coronary

artery

Partial

blockage

Right coronary

artery

The path of the tube

BALLOON WITHDRAWN

BALLOON IN POSITION

Coronary

Tube

Balloon





PERCUTANEOUS TRANSLUMINAL CORONARY ANGIOPLASTY (PTCA)/BALLOON ANGIOPLASTY/STENTING

Percutaneous Transluminal Coronary Angioplasty (PTCA)/

Balloon Angioplasty/Stenting

Balloon angioplasty or Percutaneous Transluminal Coronary Angioplasty (PTCA) is a widely-used technique

for opening blocked arteries. The procedure flattens the plaque against the artery wall to open a channel

through which more blood may flow.

Drug-coated stents are coated with very small amounts of various chemicals and medication that help

improve the way the body reacts to the placement of the stent.

Medicated stents, in particular those coated with an immunosuppressant called sirolimus, limit the amount

of scar tissue that can form and improve the stent’s ability to stay open in the long-term.

How is a PTCA or balloon angioplasty performed?

The patient will be fast overnight for the

procedure.

Before the procedure, intravenous (IV) access

is obtained to allow drugs to be administered to

the patient.

A guiding catheter is then inserted, usually

through the groin, and through which the devices

used in the angioplasty procedure are placed.

(see Figure 1)

Once the physician has located the blockage, a

guide wire is advanced down the artery and

across the blockage. The smaller balloon-tipped

catheter is then threaded across the wire until it

is positioned across the blockage, where it is

then inflated for one to three minutes. After

deflation of the balloon, the process can be

repeated at other areas. (see Figure 2)

Another procedure known as coronary stenting

often accompanies balloon angioplasty. The stent

is a small wire-mesh tube delivered to the artery

mounted as a balloon-tipped catheter and

provides a stronger, reinforced framework at the

site of the blockage. Stents help to keep the artery

open and reduces the changes that the blockage

might recur (restenosis).

The balloon is inflated, deflated and removed,

leaving behind the stent to reinforce the

artery wall.

Balloon angioplasty is a relatively quick

procedure, taking one or two hours. The patient

is usually kept under observation and monitored

for one to two nights.

Drug-coated stents

When the heart is not beating

in a smooth regular rhythm,

the irregular heartbeats are called

arrhythmia. This condition can

be dangerous.



ABLATION

TRANSCATHETER CLOSURE OF ASD


Ablation

When the heart is not beating in a regular rhythm, the irregular heartbeats are called arrhythmia. When the

heart is beating very rapidly, this type of arrhythmia is known as tachycardia. Some forms of tachycardia

may be due to an abnormal collection of conduction fibres within the heart. There are types of tachycardia

that may be treated by a procedure called ‘ablation’.

Atrial Septal Defect, or ASD, is a congenital anomaly of the heart. It is a condition commonly known as

‘hole-in-the-heart’. It refers to a hole between two upper chambers of the heart, the atria. If left untreated,

ASD may affect the lungs. Those who suffer from the condition tend to tire easily, have poor effort tolerance

or even heart failure. They may also experience irregular heartbeat.

This is an occlusive device to treat ASD, as a viable alternative to traditional open-heart surgery. Parkway

Group Healthcare is the first in Singapore to perform the transtheter closure of ASD in adults using the

Amplatzer Septal Occluder.

How is ablation performed?

There are two ways that ablation can be done: non-surgical and surgical.

The non-surgical method uses radiofrequency energy to eliminate the abnormal conduction pathways.

At the tip of the tube is a small wire, which delivers radiofrequency energy to burn away the abnormal

areas of the heart, allowing the heart to beat normally again.

In surgery, there are three ways that ablation can be performed:

a. The Maze procedure is where the surgeon makes small cuts in the heart to re-direct healthy

electrical rhythms

b. Cryoablation is where a very cold substance is introduced to freeze the cells that are creating the

problems so that these cells cannot function anymore

c. Endocardial resection is when the surgeon removes a section of the thin layer of the heart where

the abnormal rhythms come from

Transcatheter Closure of Atrial Septal Defect (ASD) in Adults

How is it performed?

What is the Amplatzer Septal Occluder?

During the procedure, a folded occluder is delivered through a catheter to ‘plug’ the hole in the heart.

First performed on children in Singapore in 1997, the method has been used to correct ASD successfully

in adults as well the following year.

It can be performed in about two hours with excellent results.

Coronary Artery Bypass Grafting (CABG)



SURGICAL PROCEDURES

CORONARY ARTERY BYPASS GRAFTING (CABG)


Coronary Artery Bypass Grafting (CABG)

Coronary Artery Bypass Grafting (CABG) or often simply known as bypass surgery is the surgical method

of treating coronary artery disease. The aim here is not to repair or remove blocked arteries but

to create a detour around the blockage: in other words, to bypass the blockage since the normal route

has been blocked. Depending on how many arteries are blocked, one, two or more bypasses may be created

at surgery.

During surgery, the surgeon takes a segment of healthy blood vessel (vein or artery) from another part of

the body and uses it as the new bypass channel.

With today’s expertise and technology, bypass surgery carries very little risks. Hospitals performing large

numbers of open-heart operations have risks of death of about 1 to 2%. Risks may vary from patient to patient

depending on factors such as old age, long-standing diabetes, previous heart attacks and strokes, kidney

failure etc. Patients who are unsure of their own risks, are advised to discuss this with their doctors.

Whatever the risk, however, they may be worth taking considering the fact that CABG significantly improves

and lengthens the quality of the patient’s life.

Bypass or ‘open heart’ surgery



SURGICAL PROCEDURES

CORONARY ARTERY BYPASS GRAFTING (CABG)

How is a bypass surgery performed?

Surgery is performed under a general

anaesthetic; hence the patient will not be aware

of the procedure.

When the patient arrives in the operating theatre,

he will already be sedated so that he will be

relaxed and calm. The anaesthetist will insert

several needle-sized tubes into the vein under

local anaesthesia. Once these are in, the patient

will be anaesthetised.

The patient will then be connected to a ventilator

via a tube inserted through the mouth or nose

into the windpipe.

An incision is made down the middle of the front

of the chest. Through this incision, the heart will

be exposed for connection to the heart lung

machine. While this is going on, another team

will be harvesting the patient’s veins from his

legs or arteries from the arm, to use as bypass

channels.

Once both teams are ready, the patient’s heart

will be stopped and the function of the heart and

lung will be taken over the heart-lung machine.

The harvested blood vessels will then be sewn

in such a way that one end is connected to the

aorta (the large artery arising from the heart)

while the other rend is connected to the coronary

artery below the level of blockage.

On completion of this part of the operation, the

patient’s heart will be made to resume its function.

When the surgeon is satisfied that the heart is

beating normally, the patient will be disconnected

from the heart-lung machine and the surgery

completed. The patient will then be taken to the

Intensive Care Unit (ICU) for monitoring.

Patients are normally monitored and managed in the ICU for one to two days. On the second day after

surgery, patient will be transferred back to an ordinary ward for recuperation. In the ward, they will be

taught how to breathe effectively and to gain confidence in their recovery process.

Most patients will be discharged from hospital in about a week and be ready to return to work in approximately

six weeks to three months.

Recovery

GLENEAGLES

HOSPITAL


Nassim Hill

Napier Road

Middlesex Road

British High

Commission

British

Council

Tanglin

Post Office

Embassy of

the United States

of America Australian

High Commission

Botanic

Gardens




MOUNT

ELIZABETH

HOSPITAL


Ngee Ann City

Wisma Atria

Shopping Centre

Lucky Plaza

Marriott Hotel

Nutmeg Road

Mount

Elizabeth

Road

Jln Elok

Tong

Building

The

Paragon

Crown Prince

Hotel

Orchard Road

Taman Serasi

Cluny Road

Mount

Elizabeth

Link

Bideford Road

WHERE WE ARE

Map not drawn to scale.

Medical Referral Centre Hotline: (65) 6735 5000 (Local Toll Free)

e-mail: mrc@parkway.com.sg

Website: www.parkwaygrouphealthcare.com

Parkway Paediatrics

Paediatrics


Looking After Our Young Patients is Kids' Stuff For Us!



- World Class Wards and Treatment


- Full Range of Care


- Making the Child Feel at Ease




World Class Wards and Treatment




We offer a complete spectrum of top-range services and medical specialties to meet the preventive, diagnostic and treatment needs of any child.



The wards are designed to put our young patients, who range from newborns to children up to 16 years of age, at ease. There is also a playroom, complete with puzzles, books and toys.



Full Range of Care



What also makes the difference in our care is the personalised touch. Our experienced and dedicated staff are ever ready to attend to your children's needs and make their stay comfortable. The nursing staff work closely with the paediatricians, forming a supportive and effective medical team.


The unit is well equipped to handle a broad range of general and paediatric surgeries for conditions such as cancer, tonsillitis, appendicitis, sinus, asthma, allergies, bone deformities, and ear, nose and throat (ENT) problems. With the latest technology and under the expert care of our team of specialists and dedicated staff, our young patients recover in good time and are able to return quickly to the mainstream of life.


Day care treatment, including chemotherapy and observation are also available.




Making the Child Feel at Ease



Parents are encouraged to stay with their children throughout the hospitalisation and meals can be arranged for them.


Every room has couches and chairs for parents to rest in during their child's stay in the hospital.



For appointments, enquiries & information, please contact our International Patient Assistance Centre (IPAC) at (65) 6735 5000.



View our attractive healthcare packages


Living Donor Kidney Transplant

Living Donor Kidney Transplant


- World Class Treatment


- Experienced Team of Multidisciplinary Professionals


- Evaluation


- Transplantation





A Better Outlook For Life


The promise of a normal, fulfilling life is the reason why patients with end-stage kidney diseases are increasingly opting for living donor kidney transplant.



Transplantation is a gift of life. It saves lives and restores the quality of life. With successful kidney transplantation, patients no longer need dialysis.


Living donor kidney transplant has shown high success rates. Once a suitable living donor is identified, transplantation can take place immediately, eliminating the long wait imposed by transplants using cadaveric donations.




World Class Treatment



Gleneagles and Mount Elizabeth Hospitals have a proven track record of performing donor kidney transplants successfully.

Our experienced, qualified teams of professionals are well-equipped with advanced technologies and equipment. You are assured of the best treatment.



Experienced Team of Multidisciplinary Professionals



Our multidisciplinary transplant teams provide you with invaluable support, guidance and care during and after your transplant.


Our transplant teams include: Transplant surgeons


Nephrologists


Anaesthesiologists


Nurse coordinator


Patient support staff



For appointments, enquiries & information, please contact our International Patient Assistance Centres at (65) 6735 5000.


Parkway Neuro Care

NEURO CARE


Caring For You With Today's Expertise and Tomorrow's Technology


- Comprehensive Treatment


- Neurological Services


- State-of-the-Art Equipment


- Dedicated Patient Care


- Related Articles




Neurological diseases are on the rise and they pose immense challenges for medical science. Early detection and treatment are required for effective results.




Being at the forefront of neurological sciences, the Parkway group has built an outstanding reputation in the region for its neurological expertise.



Our team is highly skilled in performing all types of neurosurgery. Patients receive fully integrated multidisciplinary care from our experienced team of specialists, therapists and nurses.



Patients are assured of the greatest chance for a successful outcome, as our team approach, backed by the latest medical procedures, treatment programmes and imaging technology, has proven to be highly effective.



Comprehensive Treatment


Our hospitals provide comprehensive and coordinated multidisciplinary care under one roof to patients with neurological problems, ranging from treatment for stroke, fits and brain tumour and injury to treatment for Alzheimer's and Parkinson's diseases.



Our services include advanced diagnostic tests, neurosurgical procedures, specialised post-operative care, stroke prevention and rehabilitation.




Neurological Services



Preventive Care


At our Centres, patients have access to the world's most innovative therapies. Among our comprehensive range of treatments and services are:



Health screening to identify risk factors such as high cholesterol level, hypertension, diabetes and heart disease




Diagnostic Procedures


Computerised Tomographic (CT) scans - Multislice CT scanner


MRI - Magnetic Resonance Imaging (MRI)


EEG - Electroencephalogram


EMG - Electromyogram


PET Scan - Positron Emission Tomography


Digital Substraction Angiography




Surgery


Brain and spinal surgery


CAN/CAM robotic surgery


Neurovascular surgery



Stereotactic Radiosurgery / Fractionated Stereotactic Radiotherapy


X-knife Stereotactic System (Mount Elizabeth Hospital)


BrainLab Stereotactic System (Gleneagles Hospital)




Rehabilitation


Stroke rehabilitation, including a comprehensive assessment and management by occupational therapists, physiotherapists and speech therapists




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State-of-the-Art Equipment



In Stereotactic Radiosurgery or Stereotactic Radiotherapy (SRT), a non-invasive and safe technique that has shown good results, our hospitals use modern Linear Accelerator (LINAC) based systems for treating intra-cranial tumours. Hospital stay and recovery time is reduced as hospitalisation is not needed for these procedures.



In Stereotactic Radiosurgery, a single high dosage of ionising radiation is delivered to the tumour



SRT (Stereotactic Radiotherapy) is used with a number of fractions of radiation for larger tumours, and where the tumour is very close to a critical organ, such as the optic nerve