Clinical
protocols

The Multiple Brain Metastases Protocol is primarily used for delivering a single fraction of 12 Gy to treat vestibular schwannoma. The 80% in the protocol’s name refers to a historically based concept rather than a current practical application, representing a preference for a heterogeneous dose distribution. There is no strict constraint on the maximum dose, as the focus is on achieving optimal coverage. The protocol aims to deliver 12 Gy to at least 99.7% of the target volume, while adhering to all dose constraints for critical organs.

The Multiple Brain Metastases Protocol is primarily used for delivering a single fraction of 14 Gy to treat meningioma. The 80% in the protocol’s name refers to a historically based concept rather than a current practical application, representing a preference for a heterogeneous dose distribution. There is no strict constraint on the maximum dose, as the focus is on achieving optimal coverage. The protocol aims to deliver 14 Gy to at least 99.7% of the target volume, while adhering to all dose constraints for critical organs.

The Multiple Brain Metastases Protocol is primarily used for delivering a single fraction of 20 Gy to treat both single and multiple brain metastases, as well as arteriovenous malformations (AVM). The "80%" in the protocol’s name refers to a historically based concept rather than a current practical application, representing a preference for a heterogeneous dose distribution. There is no strict constraint on the maximum dose, as the focus is on achieving optimal coverage. The protocol aims to deliver 20 Gy to at least 99.7% of the target volume, while adhering to all dose constraints for critical organs. If more than 5 lesions are treated in a single isocenter, the dose grid resolution and the Monte Carlo spatial resolution are adjusted to 2 mm to accelerate the calculation process.

This delivery arrangement is typically preferred for treating most lesions. The software is given flexibility to choose between 4 and 7 table positions, with a preference for minimizing the number of positions whenever possible. Fewer than 4 positions are avoided due to concerns about low dose distribution, while more than 7 are restricted to avoid extended treatment time without significant dosimetrical benefit. The final setup is carefully planned to prevent radiation from passing directly through the eyes and lenses.

This setup reflects the traditional arc arrangement used before the implementation of Elements. Initially, it served as a benchmark to compare whether arc optimization could match the dose distribution of our standard approach. While less common now, this setup is still occasionally employed for single lesions when we prefer full control over the treatment configuration.

This protocol is utilized in our clinic for stereotactic treatment of spine lesions. The 80% concept indicates that the PTV receives 30 Gy at the periphery with 99% coverage, while the CTV must receive at least 37.5 Gy across 65% of its volume, acting as a boost in the protocol. This ensures an adequate dose to the CTV region, while prioritizing spinal cord protection by adhering to its dose constraints.

This setup is used for all our spine cases. It consists of a full arc divided into two arc planes at a 0° gantry angle, allowing flexibility during arc optimization. A 5 mm margin between the MLC and PTV is preferred to minimize the risk of creating high-dose hotspots

This protocol is used for treating simple vestibular schwannomas for which a VMAT plan is not necessary. Elements Multiple Brain Mets SRS 3D conformal plan is generated with 12 Gy covering at least 95% of the target. PTV margin is 1 mm. OAR constraints are those used by UCLA for single fraction SRS.

This protocol is used for treating simple small meningiomas for which a VMAT plan is not necessary. Elements Multiple Brain Mets SRS 3D conformal plan is generated with 14 Gy covering at least 95% of the target. PTV margin is 1 mm. OAR constraints are those used by UCLA for single fraction SRS.

This protocol is used for treating multiple brain metastasis to 20 Gy. Elements Multiple Brain Mets SRS 3D conformal plan is generated with 20 Gy covering at least 95% of the target. PTV margin is 1 mm for all targets regardless of distance from isocenter. OAR constraints are those used by UCLA for single fraction SRS.

This protocol is used for treating multiple brain metastasis to 20 Gy. Elements Multiple Brain Mets SRS 3D conformal plan is generated with 20 Gy covering at least 98% of the target. PTV margin is 1 mm for all targets regardless of distance from isocenter. OAR constraints are those used by UCLA for single fraction SRS. This is our most frequently used protocol for brain metastasis.

A simple 3 arc geometry protocol for treating a small group of brain metastases (typically 3 or less). Allows up to 7 couch angles if necessary. Couch and arc angles are modified during planning to avoid orbits.

A simple 3 arc geometry protocol for treating a small group of brain metastases (typically 3 or less). Tries to limit number of couch angles to 3 only. Couch and arc angles are modified during planning to avoid orbits.

This protocol was originally developed for Elements Multiple Brain Mets SRS 1.5 and uses gantry angles that should avoid beams passing through the orbits for the majority of plans. With current versions of Elements Multiple Brain Mets SRS we can manually adjust the table and gantry positions, so this protocol is rarely used now.

This protocol is originally from Elements Spine SRS 1.5 and it is a very simplistic protocol. Developed for 20 Gy in 1 fraction treatments. The maximum dose limit is 120%. Most important OAR is the spinal cord. Dose grid resolution 1mm, Monte Carlo (MC) special resolution 1mm, optimization MC uncertainty is 4% and final MC forward calculation uncertainty is 1%.

This protocol is originally from Elements Spine SRS 1.5 and it is another simplistic protocol. Developed for 30 Gy in 5 fractions. The maximum dose limit is 36 Gy to 0.1% volume. Most important OAR is the spinal cord. Desired coverage is 95%. Controlled inhomogeneity is not turned on. Dose grid resolution 1mm, Monte Carlo (MC) special resolution 2mm, optimization MC uncertainty is 4% and final MC forward calculation uncertainty is 2%.

MME protocol SRS different Rx by volume: This MME protocol is used in our clinic when different sized mets need to be planned and treated in a single fraction SRS. The dose levels and volume or size threshold can be easily adjusted in the template according to your own institution protocol, and any Rx dose level can be adjusted on-the-fly in RT Elements when starting planning.

Elements Multiple Brain Mets SRS protocol for 3 fractions. Currently it is preset to 27 Gy in 3 fractions to all brain metastases, which is the most commonly used value, but the total dose can be easily adjusted to 24 Gy or 21 Gy on the fly depending on the size and location of each metastasis.

The default values are 0/360/45/90/315, and the arc optimization tool is enabled so that it can be reduced to ...to a minimum of 4 table angles and a maximum of 10 angles. The table rotation angles and gantry start and stop angles will all be optimized by Elements. One metastasis can be selected for VMAT optimization and the minimum number of arcs for VMAT is 4.

This Cranial SRS protocol is used in our clinic to treat acoustic neuroma FSRT (1.8 Gy per fraction x 26 fractions). It aims to achieve 99% volume coverage for the PTV while respecting dose constraints to all organs at risk (OAR). The most important OAR is brainstem. Cochlea on the treatment side also has a mean dose constraint set in the protocol.

This Cranial SRS protocol is used in our clinic to treat pituitary adenoma FSRT (1.8 Gy per fraction x 28 fractions). It aims to achieve 99% volume coverage for the PTV while respecting dose constraints to all organs at risk (OAR).

Protocol: 54 Gy in 30 fractions (Meningioma FSRT): this Cranial SRS protocol is used in our clinic to treat benign meningioma FSRT (1.8 Gy per fraction x 30 fractions). It aims to achieve 99% volume coverage for the PTV while respecting dose constraints to all organs at risk (OAR). Since the location of most of these cases (skull-base) involve several OARs very close to or overlapping with PTV, the optimization goal of goal of VMAT is to achieve a very homogenous dose within the PTV, so that there will be no hot spots in the treatment volumes involving OARs.

This Cranial SRS protocol is used in our clinic to treat recurrent GBM (3.5 Gy per fraction x 10 fractions). It aims to achieve 99% volume coverage for the PTV while respecting dose constraints to all organs at risk (OAR). Rx dose sometimes drops to 30Gy in 10 fxs when larger volume PTV is treated.

This Cranial SRS protocol is used in our clinic to treat uveal melanoma (10 Gy per fraction x 5 fractions). It aims to achieve 99% volume coverage for the PTV while respecting dose constraints to all organs at risk (OAR). The most important OAR is optic nerves on both sides.

This Cranial SRS protocol is used in our clinic to treat single PTV SRS with VMAT or dynamic arcs technique. It aims to achieve 99% PTV volume covered by the prescription dose while respecting dose constraints to all organs at risk (OARs). CI, GI, and V12Gy are used to evaluate the plan, with higher priority given to reducing the normal tissue dose. The indications could be brain mets (15 ~ 24 Gy) or any benign tumor such as meningioma (14 ~15 Gy), acoustic neuroma (12Gy), and AVM (18~21 Gy).

Designed for radiosurgery of multiple brain metastases with diameters less than 3 cm (or 15 cc). Dose prescription varies with lesion volume (18 or 20 Gy). Even larger lesions typically receive fractionated treatment but may be included in a single fraction if appropriate. The 75% isodose line prescription is used.

Designed for radiosurgery of multiple brain metastases with diameters less than 3 cm (or 15 cc). Dose prescription varies with lesion volume (18 or 24 Gy). Even larger lesions typically receive fractionated treatment but may be included in a single fraction if appropriate. The 75% isodose line prescription is used.

Used for the irradiation of multiple brain metastases in 3 fractions with a single dose of 9 Gy per fraction. The 75% isodose line prescription is used. This template is selected for metastases between 2-3 cm (or 4-15 cc) or when organ constraints need to be met.

Used for the irradiation of multiple brain metastases in 5 fractions with a single dose of 6 Gy per fraction. The 75% isodose line prescription is used. This template is selected for metastases between 3-4 cm (or 15-33 cc) or when organ constraints need to be met.

Stock template with all Arc Optimization features enabled. 3 to 7 table angles are used. Start/stop gantry and couch angles are optimized.

Used for head irradiation without isodose line prescription (no dose escalation) in 13 fractions.

Radiosurgery for a single brain metastasis with a standard prescription of 24 Gy, typically used for metastases smaller than 2 cm in diameter (or 4 cc). For larger lesions (up to 15 cc), the dose can be manually adjusted to 18 Gy. The 75% isodose line prescription is used.

No standard fractionation. This template is used when one fraction of a 3-fraction metastasis has already been treated in a multi-metastasis plan. Parameters are scaled to match the 3-fraction template.

Used for head irradiation without isodose line prescription (no dose escalation) in 30 fractions.

Used for the irradiation of a single brain metastasis in 3 fractions, suitable for lesions with a diameter of 2-3 cm (or between 4 and 15 cc). The 75% isodose line prescription is used.

Used for the irradiation of a single brain metastasis in 5 fractions, suitable for lesions with a diameter of 3-4 cm (or between 15 and 33 cc). The 75% isodose line prescription is used.

This Elements Cranial SRS w/ Cones protocol is used for trigeminal nerve treatment. The prescription is 90 Gy in 1 fraction with an isocenter normalization. Collimation is performed using stereotactic cones of 4, 5 or 6 mm diameter. Choice of the cone diameter will depend on trigeminal nerve size (80 Gy isodose should cover nerve section), patient anatomy (trigeminal nerve / brainstem distance) and their clinical situation. 5 mm cone diameter is mostly used.

Irradiation is carried out using 8 non-coplanar quarter arcs. This geometry allows a butterfly absorbed dose distribution, reducing absorbed dose on the brainstem..