Radiation Techniques Used by Dr. Geeta Singh
Modern radiation oncology has evolved far beyond the concept of simply directing radiation toward a tumor. Today, treatment planning combines detailed imaging, computer-based dose calculations, precise target delineation, image guidance and carefully designed radiation delivery techniques.
As a Radiation Oncologist, Dr. Geeta Singh has clinical experience with a range of radiation techniques, including 3D Conformal Radiation Therapy (3DCRT), Image-Guided Radiation Therapy (IGRT), Intensity-Modulated Radiation Therapy (IMRT), Volumetric Modulated Arc Therapy (VMAT), Surface Guided Radiation Therapy (SGRT), Stereotactic Body Radiation Therapy (SBRT), Brachytherapy and Stereotactic Radiosurgery (SRS).
The choice of technique is not based simply on which technology is newest or most advanced. It depends on the individual patient’s diagnosis, stage of disease, tumor location and size, relationship to nearby organs, previous treatments, treatment intent and overall clinical circumstances.
The objective is to develop a treatment plan that provides appropriate radiation to the intended target while considering the protection of surrounding healthy tissues.
3D Conformal Radiation Therapy (3DCRT)
What is 3D Conformal Radiation Therapy?
3D Conformal Radiation Therapy (3DCRT) is an external beam radiation therapy technique in which treatment is planned using three-dimensional imaging.
CT imaging is commonly used for treatment simulation and planning, while MRI or PET information may also be incorporated when clinically appropriate. The treatment planning system uses these images to define the treatment area and calculate how radiation beams can be arranged to conform to the shape of the target.
The fundamental principle is to shape the radiation delivery around the three-dimensional geometry of the tumor or treatment volume.
Modern linear accelerators use a device called a multileaf collimator (MLC), consisting of multiple movable metal leaves that can shape the radiation field. This allows the treatment team to create radiation fields appropriate to the target while limiting unnecessary exposure to surrounding tissues.
How does 3DCRT work?
Before treatment begins, the patient undergoes a planning CT scan in the treatment position. The radiation oncology team then identifies the target and relevant nearby organs at risk.
Using treatment planning software, radiation beams are arranged from different directions to achieve the desired dose distribution.
The treatment plan is evaluated before treatment is delivered to ensure that the prescribed dose can be delivered appropriately to the target while respecting the required dose limits for surrounding normal tissues.
Where can 3DCRT be used?
3D conformal radiation therapy can be used for a variety of cancers and treatment situations. The appropriate technique depends on the individual clinical circumstances.
Radiation treatment planning may involve areas such as the brain, head and neck, chest, abdomen, pelvis and other anatomical sites.
The number of treatment sessions varies according to the type and stage of cancer, treatment intent, target location and the prescribed radiation schedule.
Image-Guided Radiation Therapy (IGRT)
What is IGRT?
Image-Guided Radiation Therapy (IGRT) uses imaging to help verify patient positioning and treatment anatomy in relation to the planned radiation treatment.
Radiation therapy is planned in three dimensions, but the patient’s position and internal anatomy can vary between treatment sessions. Breathing, organ filling, digestion and small changes in positioning can all contribute to differences between the planned and actual treatment setup.
IGRT provides additional imaging information to help the radiation therapy team identify and address these variations.
According to the American Society for Radiation Oncology (ASTRO), IGRT has expanded beyond stereotactic treatments and is now used across many treatment techniques and anatomical sites where appropriate.
How does IGRT work?
Depending on the treatment system and clinical requirement, imaging may be obtained before or during treatment. The resulting images can be compared with reference images from the treatment planning process.
This allows the treatment team to verify the patient’s position and, when necessary, make appropriate adjustments before radiation is delivered.
IGRT may be particularly valuable when treating tumors that can move with breathing or other physiological changes, or when the target is located close to sensitive organs.
Why is IGRT important?
Accurate positioning is an important part of radiation treatment delivery.
IGRT provides an additional layer of verification between the treatment plan and treatment delivery. It can therefore support the accurate delivery of highly conformal and stereotactic treatments as well as many routine radiation treatments.
Intensity-Modulated Radiation Therapy (IMRT)
What is IMRT?
Intensity-Modulated Radiation Therapy (IMRT) is an advanced form of external beam radiation therapy that allows the intensity of radiation to vary across different portions of the treatment field.
Unlike conventional radiation fields in which the radiation intensity is more uniform across a field, IMRT uses multiple smaller beam segments with different intensities to create a more precisely optimized dose distribution.
The National Cancer Institute describes IMRT as a form of three-dimensional conformal radiation therapy in which multiple beam directions and varying beam intensities are used to create a more tailored radiation dose distribution.
How is IMRT planned?
IMRT relies on sophisticated computer-based treatment planning.
The radiation oncology team first defines the target volumes and identifies nearby organs at risk (OARs) that require protection.
Treatment planning software then calculates and optimizes the radiation dose distribution based on the clinical objectives.
The plan is reviewed carefully before treatment begins to assess target coverage and doses delivered to surrounding organs.
When can IMRT be useful?
IMRT can be particularly valuable when a tumor is located close to important normal structures.
This can be relevant in areas such as the head and neck, brain, pelvis, abdomen, thorax and other anatomically complex regions.
The technique may allow the radiation dose to be shaped more closely around an irregular target while reducing dose to selected surrounding normal tissues.
However, IMRT is not automatically the best technique for every patient. The appropriate treatment method depends on the patient’s individual anatomy, diagnosis and treatment objectives.
Volumetric Modulated Arc Therapy (VMAT)
What is VMAT?
Volumetric Modulated Arc Therapy (VMAT) is an advanced radiation delivery technique in which the treatment machine rotates around the patient while radiation is delivered.
During the rotation, treatment parameters can be continuously adjusted according to the treatment plan. These may include the radiation dose rate, beam aperture and rotation speed.
This allows the radiation dose to be modulated from multiple directions around the patient.
How does VMAT work?
The treatment planning system determines how radiation should be delivered throughout the arc or arcs required for the treatment.
The treatment machine then rotates around the patient while delivering radiation according to the optimized plan.
The result is a highly modulated three-dimensional dose distribution designed to provide appropriate target coverage while meeting dose constraints for surrounding organs.
VMAT is recognized within the broader group of intensity-modulated radiation techniques and is included by ASTRO among established radiation treatment modalities.
Where can VMAT be used?
VMAT can be used for a wide range of solid tumors when clinically appropriate.
It may be particularly useful for complex treatment volumes where radiation needs to be shaped around nearby organs and structures.
The technique may be used in cancers involving regions such as the head and neck, brain, thorax, abdomen and pelvis, among others.
The decision to use VMAT is based on the individual treatment plan rather than the cancer diagnosis alone.
Surface Guided Radiation Therapy (SGRT)
What is SGRT?
Surface Guided Radiation Therapy (SGRT) is a non-contact technology that uses optical surface imaging to monitor the patient’s external surface and position during radiation treatment.
It provides the treatment team with additional information about patient positioning and movement without requiring physical contact with the patient.
SGRT is particularly relevant to modern precision radiation workflows where accurate positioning and motion monitoring are important.
ASTRO’s accreditation standards recognize IGRT/SGRT and motion management among radiation oncology treatment techniques and processes.
How does SGRT work?
Before treatment, the patient’s external surface is captured using an optical imaging system and compared with a reference surface.
The system can continuously monitor the patient’s surface during the treatment process.
If movement exceeds the predefined parameters for a particular treatment workflow, the system can provide an alert or support interruption of treatment so that the radiation therapy team can assess the patient’s position.
SGRT in breast cancer radiotherapy
SGRT can be particularly useful in selected breast cancer treatment workflows.
Breast radiotherapy may involve respiratory motion and, in selected patients, techniques such as Deep Inspiration Breath Hold (DIBH) may be used.
SGRT can provide surface and respiratory motion information that can support such workflows when clinically appropriate.
It is important to understand that SGRT is a treatment-positioning and motion-monitoring technology. It does not independently determine the patient’s treatment or replace the clinical judgment of the radiation oncology team.
Dr. Geeta Singh’s SGRT expertise
Dr. Geeta Singh’s professional training includes Advanced Clinical Training – Surface Guided Radiation Therapy (SGRT) at Kalyan Singh Super Speciality Cancer Institute & Hospital, issued in February 2026.
Her listed training includes SGRT applications in modern radiation oncology and stereotactic treatments such as SRS/SBRT.
Stereotactic Body Radiation Therapy (SBRT)
What is SBRT?
Stereotactic Body Radiation Therapy (SBRT) is a highly precise form of external beam radiation therapy that delivers radiation to a carefully defined target using stereotactic treatment principles.
Compared with many conventional radiation schedules, SBRT can deliver a relatively high radiation dose per treatment session over a smaller number of treatment sessions in appropriately selected patients.
The technique requires accurate treatment planning, patient immobilization or positioning, image guidance and rigorous quality assurance.
ASTRO emphasizes that SRS and SBRT require appropriately trained teams, specialized technology and comprehensive quality-assurance processes.
How does SBRT work?
SBRT begins with detailed imaging and treatment planning.
The target is carefully delineated, and surrounding organs at risk are identified. The treatment plan is designed to deliver the prescribed dose to the target while respecting the dose limits of nearby normal structures.
Because SBRT involves high-precision treatment, accurate patient positioning and image guidance are particularly important.
When can SBRT be considered?
SBRT may be considered for selected patients with certain localized tumors or limited metastatic disease, depending on the location, size, number of lesions, previous treatments and overall clinical situation.
It can be used in appropriately selected cases involving sites such as the lung, liver, spine and other locations.
SBRT can also have a role in selected patients who are not suitable candidates for surgery.
However, SBRT is not appropriate for every patient or every tumor. Careful clinical assessment is essential before recommending stereotactic treatment.
Brachytherapy
What is Brachytherapy?
Brachytherapy is a form of internal radiation therapy in which a radiation source is placed inside the body, in or near the area requiring treatment.
Unlike external beam radiation therapy, where radiation is generated outside the body and directed toward the target, brachytherapy places the radiation source close to the treatment area.
The National Cancer Institute describes brachytherapy as a local treatment in which radiation sources such as seeds, ribbons or capsules are placed in or near a tumor.
How is brachytherapy delivered?
Depending on the type of cancer and treatment approach, radioactive sources may be delivered using specialized applicators, catheters or other techniques.
Brachytherapy can be delivered using different dose-rate approaches, including high-dose-rate (HDR) and low-dose-rate (LDR) techniques.
The exact procedure depends on the treatment site and clinical indication.
Why is brachytherapy useful?
Because the radiation source is positioned close to the treatment target, brachytherapy can provide a highly localized radiation dose with a rapid reduction in dose as the distance from the source increases.
This makes it particularly useful for selected cancers where the target can be accessed appropriately.
Brachytherapy has established applications in cancers including cervical, endometrial, vaginal, breast and prostate cancers, among others.
Brachytherapy in gynecological cancers
Brachytherapy plays an important role in the radiation treatment of selected gynecological cancers, particularly cervical cancer.
The treatment is planned according to the patient’s anatomy, tumor characteristics and the surrounding organs at risk.
Imaging can be incorporated into the treatment planning process where appropriate to improve target and organ-at-risk assessment.
Stereotactic Radiosurgery (SRS)
What is SRS?
Stereotactic Radiosurgery (SRS) is a highly precise radiation treatment technique.
Despite the word “surgery” in its name, SRS does not involve a conventional surgical incision. Instead, highly focused radiation is delivered to a precisely defined target.
SRS is most commonly associated with selected tumors and lesions in the brain and other intracranial locations.
ASTRO recognizes SRS as a specialized radiation treatment modality and emphasizes the importance of appropriate quality and safety processes for stereotactic treatments.
How does SRS work?
SRS uses highly accurate treatment planning and stereotactic localization to deliver radiation to a defined target.
Multiple radiation beam directions can be used so that radiation converges on the intended target while limiting exposure to surrounding normal brain tissue as much as clinically possible.
Depending on the clinical situation, SRS may be delivered in a single treatment session or in a small number of highly precise treatment sessions.
When can SRS be used?
SRS can be considered for selected intracranial conditions, including certain brain metastases and other appropriately selected brain or skull-base tumors and lesions.
The suitability of SRS depends on factors such as the number, size and location of lesions, proximity to critical structures, previous treatments and the patient’s overall clinical condition.
A detailed assessment is required before stereotactic treatment is recommended.
Choosing the Right Radiation Technique
There is no single radiation technique that is best for every cancer patient.
The most appropriate approach depends on several factors, including:
- Type of cancer
- Stage of disease
- Tumor size
- Tumor location
- Relationship to nearby organs
- Number of lesions
- Previous surgery or radiation therapy
- Other treatments being given
- Overall health and performance status
- Treatment intent
- Expected benefits and potential risks
A treatment that is highly appropriate for one patient may not be appropriate for another patient with the same type of cancer.
This is why radiation treatment planning is an individualized process.
From Diagnosis to Precision Treatment
Modern radiation therapy involves considerably more than selecting a machine or treatment technique.
The process begins with understanding the patient’s diagnosis and staging.
Relevant pathology, CT, MRI, PET or other imaging information may then be reviewed and incorporated into the treatment planning process when appropriate.
The radiation oncology team identifies the target volumes and organs at risk, determines the appropriate treatment approach, develops and evaluates the treatment plan, and verifies treatment delivery according to established clinical and quality-assurance procedures.
Techniques such as 3DCRT, IMRT, VMAT, IGRT, SGRT, SBRT, SRS and brachytherapy are tools within this larger process.
The goal is not simply to use advanced technology. The goal is to use appropriate technology for the individual patient.
Precision With a Patient-Centered Approach
As a Radiation Oncologist, my approach is centered on combining clinical assessment with appropriate technology and careful treatment planning.
Every patient brings a different diagnosis, anatomy, treatment history and set of concerns.
My role is to understand these factors, explain the available treatment options clearly, and determine whether radiation therapy has a role in the overall cancer treatment plan.
Advanced radiation techniques can provide important opportunities for precision, but technology should always remain connected to sound clinical decision-making and patient-centered care.
Precision in radiation oncology is not only about the technology we use. It is about making the right clinical decisions, defining the right treatment target, delivering the prescribed treatment accurately and caring for the patient throughout the treatment journey.
Frequently Asked Questions
Is advanced radiation therapy suitable for every cancer patient?
No. The appropriate radiation technique depends on the type, stage, location and characteristics of the cancer, as well as the patient’s previous treatments and overall clinical condition.
Is IMRT better than 3DCRT?
Not necessarily. IMRT can provide more complex dose modulation and may be advantageous for selected treatment situations, particularly when the target is close to sensitive organs. However, the appropriate technique should be determined from the individual treatment plan.
What is the difference between IGRT and SGRT?
IGRT uses imaging to verify treatment position and anatomy, while SGRT uses optical surface imaging to monitor the patient’s external surface and movement. They can serve complementary roles within a radiation treatment workflow.
What is the difference between SBRT and SRS?
Both are stereotactic radiation techniques. SBRT generally refers to stereotactic radiation delivered to targets outside the brain and central nervous system, while SRS is most commonly used for selected intracranial targets. The exact treatment approach depends on the individual clinical situation.
Is brachytherapy a type of radiation therapy?
Yes. Brachytherapy is internal radiation therapy, in which a radiation source is placed in or near the area being treated. It differs from external beam radiation therapy, where radiation is delivered from a machine outside the body.
Does radiation therapy always require many treatment sessions?
No. The number of treatment sessions varies considerably depending on the cancer, treatment intent, technique and prescribed dose. Conventional radiation schedules may involve multiple sessions, while selected stereotactic treatments can be delivered in fewer sessions.
Does advanced radiation therapy mean there will be no side effects?
No. Radiation therapy can cause side effects, and the type and severity depend on the treatment area, dose, technique and individual patient factors. Advanced planning and delivery techniques are designed to improve precision and can help manage radiation exposure to surrounding healthy tissues, but they cannot eliminate all treatment-related effects.
Expert Radiation Oncology Care
Dr. Geeta Singh brings experience in modern radiation oncology, including 3DCRT, IGRT, IMRT, VMAT, SGRT, SBRT, SRS and brachytherapy, with an approach that combines precision-driven treatment planning with multidisciplinary and patient-centered cancer care.
If you have been diagnosed with cancer and have been advised radiation therapy, a radiation oncology consultation can help you understand whether radiation is appropriate, which treatment approach may be suitable, what the treatment involves and what you can expect during your care.
Book a Consultation with Dr. Geeta Singh
Individual treatment recommendations can only be made after reviewing the patient’s diagnosis, examination, pathology, imaging and complete clinical history.
