Radiation Oncology

Successful treatment outcome in radiation oncology is based on irradiation of tumour-bearing tissues to adequate, or curative, doses; and the sparing of normal, or uninvolved, tissues from unnecessary radiation.Recent improvements in powerful computer systems and treatment planning software allow physicians to visualize a patient’s anatomy in three dimensions relative to the radiotherapy treatment machines which enables them to “conform” a radiation dose more closely to the shape of an individual’s tumour. Three-dimensional treatment planning improves the accuracy of planning, resulting in both better coverage of tumors and reduced treatment of normal tissues. Higher doses of radiation may be delivered to some tumours without increasing the risk of side effects of treatment. We routinely use 3D-CRT for all curative treatments.

IMRT is a more advanced form of radiation treatment. IMRT imparts a high dose of radiation to a localized tumour from multiple angles. A large number of very fine radiation beams of varying intensity target the tumour while minimizing the dose to the surrounding healthy tissue. The result is that side effects are reduced, and the chance of eradicating the tumour is increased. We use IMRT for clinical situations where critical normal structures are very close to the tumour or when a higher dose of radiation is required for tumour eradication.

(Also called Brachytherapy), internal radiation therapy uses sealed radioactive sources for cancer treatment. These can be in the form needles, wires, seeds etc. Earlier internal radiation required hospital stay for 3 to 5 days in isolated rooms. But presently with HDR [High Dose Rate] brachytherapy available in our institution, the treatment can be taken on an out-patient basis. The time period of treatment is less than an hour. Internal radiation is usually delivered in one of two ways:
Interstitial Radiation Therapy – the sources are directly inserted into the tumour under anesthesia. It is used to treat tumors of the head and neck, cervix, breast, limbs, perianal and pelvic regions.
Intracavitary or intraluminal radiation therapy – done by inserting tube (catheters /applicators) into the body cavities and passages to take the sources near the tumor. It is commonly used in the treatment of cancer of uterus cervix, vagina, esophagus [food pipe], trachea and bronchus (wind pipes in the neck and lungs), and gallbladder.

Stereotactic (or stereotaxic) radiosurgery uses a large single dose of radiation to a small target area within the head. The procedure does not involve actual surgery. Very high precision and accuracy is ensured by fixing a special frame to the patient’ head with which the patient is scanned. These images are fed into sophisticated computers where they are fused with diagnostic scan images (MRI/MR angiogram/MDCT/DSA ). The target is localized precisely in dimensional space and radiation is delivered very accurately to the target sparing the nearby tissues. Some times steriotactic radiation is delivered in multiple fractions spread over several days. This is called steriotactic radiotherapy. The department has a linear accelerator based X- Knife for this procedure. The most common conditions treated are:

• Arteriovenous/vascular malformations
• Trigeminal Neuralgia
• Malignant and benign brain tumors
• Intracranial metastases
• Meningioma
• Acoustic tumors
• Pituitary tumours

Total body irradiation (TBI) gives a dose of radiation to the whole body. TBI is used for patients about to undergo a bone marrow or stem cell transplant to destroy any undetectable cancer cells and also to produce immune suppression in patients undergoing organ transplant so that the immune system will not attack the donor’s cells during the transplant.
TBI can eradicate cancer cells in areas of the body that chemotherapy may not reach. However, the dose of radiation must be low enough so that the body’s healthy cells can recover. For this reason, TBI alone cannot be used to destroy large numbers of cancer cells. Instead, the transplant preparative regimen uses TBI along with high-dose chemotherapy. Treatments are usually delivered one to three times a day for two to four days. The schedule will be based on the treatment plan (protocol) and the diagnosis and other factors. The treatment may be carried out in standing or lying down. Each treatment session may take 30 to 60 minutes. After completion of radiation treatment patient will be scheduled for bone marrow transplant.

This technique permits delivery of high doses of radiation to the skin without treatment to the underlying tissues and organs. It is especially useful in the treatment of mycosis fungicides (coetaneous T-cell lymphoma) and other rare lymphomas of the skin. The Linear accelerator in the department is equipped with facility for generating high dose rate electrons for this treatment. The treatment is usually given on alternate days and may take 4 to 6 weeks for completion.

The department is equipped with strontium 90 ophthalmic applicator which is used to treat eye tumors (both benign and malignant) an example is recurrent pterygium which almost always recurs and each successive recur¬rence a grave threat to the patient’s vision and much more difficult to control. Postoperative radiation because of its simplicity, minimum morbidity, excellent cosmetic results and good cure rates. This applicator can also be used to treat other eye conditions like superficial conjunctival tumours is commonly recommended.

These units are used for external beam treatment to treat all tumours. Two identical Elekta Precise digital linear accelerators with triple photon and multiple electron are available. Both linear accelerators have amorphous portal imaging system for verification of treatment fields. These units are capable of delivering 3Dimensional conformal therapy (3D CRT), Intensity Modulated Radio Therapy (IMRT) and Stereotactic Radio Surgery. Even if there is breakdown in one machine, since both machines are identical, It is easier to treat all patients without interruption.

Stereotactic (or stereotaxic) radiosurgery uses a large single dose of radiation to a small target area within the head. The procedure does not involve actual surgery. Very high precision and accuracy is ensured by fixing a special frame, to the patient’ head with which the patient is scanned. These images are fed into sophisticated computers where they are fused with diagnostic scan images (MRI / MR angiogram /MDCT /DSA ). The target is localized precisely in dimensional space and radiation is delivered very accurately to the target sparing the nearby tissues. Some times steriotactic radiation is delivered in multiple fractions spread over several days. This is called steriotactic radiotherapy. The department has a linear accelerator based X- Knife for this procedure.The most common conditions treated are:

• 3D Line ERGO++ treatment planning system is used for Stereotactic Radiosurgery (SRS) and Stereotactic Radiation Therapy (SRT).
• The advantage is (small tumour can be completely controlled without) a major NeuroSurgical Procedure.
• SRS Frames help localize the target.
• Micro MLC s are used to define the treatment field.

High Dose Rate after loading system with CT Scan image based treatment-planning system. The treatment unit and the computerised planning system is Micro Selectron and Plato from Nucletron, Netherlands. This helps to deliver a high dose to the tumour with minimal dose to the adjacent normal structures. Also the treatment is completed in a relatively short time.

Dedicated high-end computers and high-end software programs are used to plan/tailor radiation treatment and to localize the tumor target. These tools are critical for precise delivery of high dose radiation. This system comprises four HP servers and ten workstations with XiO / Focal software from Computerised Medical System, USA. XiO / Focal is a comprehensive 3-D / IMRT treatment planning platform that combines the latest tools and most robust dose calculation algorithms to generate plans quickly and accurately to optimize the delivery of radiation therapy.

CT Simulator is a CT scanner with special software and moving laser beams.. These CT scans are used to localize the tumor and other critical organs around the tumor. They help to ensure delivery of adequate dose to target volume with minimum possible dose to critical structures.
Diagnostic radiographs, angiograms, CT, PET – CT and MRI scans, are also used in radiation treatment planning. These technologies offer doctors a clear picture of the tumour allowing precision planning for treatments involving 3-D CRT. IMRT and SRS / SRT.

An X-ray machine called a ‘simulator’ is used to plan and verify treatment ports for radiotherapy treatment. It is called a simulator because it is built to simulate (or be like) a radiotherapy machine, but without giving the treatment. The Simulix EVOLUTION simulator is the ultimate new-generation simulator, incorporating digital flat panel technology.

The availability of all associated departments under a roof makes the management of most malignancies easier for the patient and physician. There is a strong emphasis on multi-disciplinary approach to treat the patient with tumor board meetings being held regularly to discuss the cases and decide the best management options for the patient.