Role of Radiation in Cancer Treatment
Radiation for cancer is based on the use of ionizing radiation for killing cancer cells. Ionizing radiation can be either very high energy x-rays (megavoltage x-rays), gamma rays, high energy electrons etc. Radiation interacts with the atoms and molecules in the body to produce DNA damage that is responsible for cancer cell death. During its passage to the cancer, radiation also passes through normal body tissues and can cause some damage to the normal tissues. Normal tissues have a higher capability for recovery and the gap between two fractions allows normal tissue to recover. However, minimizing exposure of normal tissues is a critical component of radiation treatment planning and delivery today. High quality radiation therapy services ensure that cancer receives the maximum dose of radiation while normal tissues get a negligible dose.
Radiation can be used alone to cure many cancers, especially in early stages. Curative treatment with radiation is possible for many head and neck cancers, some lung cancers, prostate cancer, cancer of uterine cervix, skin cancers, Hodgkin's lymphoma, etc. Advantage of using radiation in this way is that there is no surgery involved. Organ and function conservation thus becomes feasible for many cancer patients. High cure rates are achieved in most of these situations that are at par with surgical treatment.
In addition to this, radiation can be used as part of multimodality management of cancer. Such use is possible in the following settings:
Post-operative adjuvant radiation therapy: Radiation therapy to the operative tumor bed can kill microscopic cancer cells remaining in the tumor bed and increase the cure rates and long term survival. Adjuvant radiation is used in breast cancer, colorectal cancer, bone and soft tissue cancers, brain tumors, head and neck cancers, esophagus and stomach cancers etc.
Pre-operative radiation therapy: Radiation therapy can reduce the tumor size and improve the possibility of successful surgery in locally advanced cancers. Preoperative RT is used in head and neck cancer, rectal cancer, esophageal cancers, etc.
Concomitant chemo-radiotherapy: Radical treatment of large or locally advanced cancers has undergone a revolution with the development of concomitant use of chemotherapy and radiation therapy. In this approach, chemotherapy is used to improve the results of radiation therapy primarily and not for control of distant metastases. Such approach has been very useful in head and neck cancers, esophageal cancers, cancer of uterine cervix, brain tumors, rectal cancers, cancer of urinary bladder, lung cancers, pancreatic cancers, etc.
Palliative radiotherapy: Radiation is a very effective tool for symptom control in advanced cancers that are not candidates for curative treatment.
Palliative radiation is used for following situations :
Intensity Modulated Radiation Therapy (IMRT)
- Brain metastases
- Bone metastases
- Obstruction of superior vena cava (SVC Obstruction)
- Obstruction of esophagus, trachea-bronchial tree etc.
- Bleeding from cancers
- Any pain due to large /advanced tumors
Intensity modulated radiation therapy (IMRT) is based on variation in the intensity of radiation dose within different parts of a radiation field. This allows complex shaping of radiation fields including concavities. High quality radiation delivery for IMRT has to be complemented with specialized treatment planning for IMRT. Inverse planning approach is used for IMRT treatment planning that permits limiting the radiation dose to the organs at risk near the radiation target.
3D Conformal Radiation Therapy (3DCRT)
Conforming radiation field to the target area and avoiding normal surrounding tissues is capable using multileaf collimators and used forward planning techniques. 3D CRT is a radiation technique that occupies a place between standard or conventional RT and IMRT. It is useful in many body areas when IMRT is not necessary but standard radiation includes lot of normal tissues and limits the delivery of higher doses of radiation. Presence of Multileaf collimator at Institute of Cancer Sciences allows 3DCRT to be of a much higher quality that what is available at most other centers.
Conventional Radiation Therapy
Conventional radiation therapy at Institute of Cancer Sciences is used for cases not required advanced techniques of radiation. While not comparable to 3D CRT/IMRT/IGRT, conventional RT at Institute of Cancer Sciences is of a very high quality. Planning for conventional RT is also done based on CT scanning of the tumor and normal tissues. Further, immobilization of the patient using thermoplastic mask system and other accessories improves the results of conventional RT. Linear accelerator based conventional RT is significantly superior to conventional RT based on cobalt teletherapy units. The damage to skin and superficial tissues is minimized in the linear accelerator based RT. Institute of Cancer Sciences also has the capability for Irradiation of blood products is used in some patients with hematological diseases. Electron beam irradiation is useful for treatment of some superficial lesions for giving radiation boost doses to some targets.
Brachytherapy or internal delivery of radiation therapy is an essential technique of RT that makes a radiation facility complete. Brachytherapy allows high radiation doses to be delivered within the tumor without the radiation passing through normal tissues.
Brachytherapy is critical in achieving high cure rates in gynecological cancers such as cancer of cervix and cancer of uterine body (endometrium). In addition, it is used for prostate cancer, breast cancer, esophageal cancer, head and neck cancers, soft tissue sarcomas, skin cancers, bronchial tumors, hepatobiliary tumors, brain tumors, etc. Based on the route of application, brachytherapy is divided into intracavitary, intraluminal, interstitial, surface mold, etc.
Institute of Cancer Sciences has the highest quality brachytherapy delivery capability due to the following reasons:
30 channel brachytherapy machine
Widest range of brachytherapy applicators
Capability for image guided brachytherapy delivery
Inverse planning brachytherapy capability
Team of senior consultants and physicists with vast experience in brachytherapy
Radiation Oncology is a technology driven department. Rapid pace of technological changes also means that the department has to constantly upgrade itself to be at the leading edge of the field, both in technology and in updating the skills of its team. Institute of Radiation Oncology, Choithram Hospital and Research Centre is equipped with the most advanced technology available in the world for providing the best radiation treatment to their cancer patients.
External Beam RT
Institute of Radiation Oncology, Choithram Hospital and Research Centre is equipped with an IMRT capable single linear accelerator from Siemens Primus, Germany. The highlights of the system are:
Photon energy 6 MV
Multiple electron energies ( 5 MeV to 14 MeV)
aS amorphous silicon based digital portal imaging device (EPID)
Completely computerized record and verification system
Fully networked department of radiation oncology with data and image server
Advanced treatment planning system (TPS) for inverse planning using advanced algorithms, multiple planning workstations for rapid workflow management, multiple contouring stations with advanced contouring capabilities
Immobilization and mould room
Since radiation treatment is delivered in a divided/fractionated plan, it is critical to ensure that the same area of the body receives the radiation with a high degree of accuracy. High quality mould room facilities and immobilization are essential to ensure this. Institute of Radiation Oncology, Choithram Hospital and Research Centre has invested in the best mould room and immobilization technology.
Custom fit vacuum cushion system :
Vacuum cushions (Vacloc) ensure rigid yet comfortable support to the patient to minimize deformation of body while lying on the treatment table. A custom cushion is prepared for the patient at the beginning of treatment and is used for each treatment session.
Thermoplastic mask system :
Thermoplastic masks (Orfit) from the global pioneers in the field are used in addition to the vacuum cushion system to prevent patient movement. Together, the two make for a near perfect immobilization solution. Custom masks are also prepared for the patient at the start of the treatment and used during each treatment session.
Foam rests for head, neck, arms, knees etc. :
To ensure patient comfort while making him immobile, comfortable foam rests are used for each patient.
40 slice CT scanner from Siemens Medical Systems is used for CT based simulation of all patients treated at Institute of Radiation Oncology, Choithram Hospital and Research Centre. Moving lasers are installed in the CT room for accurate positioning and simulation of the cancer treatment. High quality thin slice imaging with contrast is used to ensure the best possible visualization of the tumor and normal tissues.
CT based simulation is supplemented by 1.5 Tesla high quality MRI imaging when considered necessary. MRI imaging is especially useful in radiation treatment of brain tumors.
High end virtual simulation software from Oncentra Treatment planning Systems is used for contouring of the tumor and normal tissues in three dimensions. Advanced options like beam's eye view etc are available in the system for high quality treatment planning.
Quality assurance of the equipment and quality checking of all treatment plans is mandatory for all radiation treatment. High quality equipment helps in ensuring that patients get the planned treatment without any toxicity Institute of Radiation Oncology, Choithram Hospital and Research Centre has invested in the highest quality of QA equipment from PTW of Germany. The equipment consists of
High dose rate brachytherapy systems are the de facto standard for internal radiation or brachytherapy. Based on a small radiation source (Iridium 192) driven by computer control, these systems offer the convenience of fast and highly optimized treatment of a large variety of tumors while reducing the dose to normal tissues.
Institute of Radiation Oncology, Choithram Hospital and Research Centre has commissioned a thirty channel remote afterloading HDR brachytherapy unit from Nucletron BV of Netherlands, the world leader in brachytherapy systems. Combined with 3D and inverse planning capabilities, wide range of CT and MR compatible applicators, the system is capable of "Image Guided Brachytherapy", the most advanced form of brachytherapy available today.
Radiation Team Members
Physicians (Radiation Oncologists)
Dr. Aarti Kaul Patel
Dr. S.P. Shrivastava
Dr. Rajendra Kumar Aanjne
Physicists (Medical physicists)
Mr. Atul Kumar Tiwari
Mr. Avtar Singh
Technologists (Radiation Therapy Technologists)
Mr. Jeen SP Sathiya
Mr. Pramod Kumar
Mr. Ramesh Kumar