Best Medical Canada has been the pioneer of in-vivo dosimetry for radiotherapy, brachytherapy and radiology applications for over 30 years. BMC MOSFETs (TN-502RD-H) are real-time dose readout dosimeters that connect to a wireless and battery-operated mobileMOSFET reader. The advanced features of the software allow for dose verification in comparison to target dose, and electronic dose reporting with data transfer to R&V systems. The hand-held Portable Dosimeter system is intended for cost-effective MOSFET dosimetry and portability during clinical use at uncompromised accuracy. BMC MOSFETs, based on patented dual MOSFET technology, are the only in-vivo dosimeters with unmatched dosimetric characteristics such as temperature independence, gantry angle, dose rate, energy and good linearity at full dose range.

In addition, we have developed various product accessories providing tools to enhance the quality of treatment delivered by medical professionals. For example, we provide build-up caps for Dmax measurements and different types of dosimeters tailored towards various applications in radiotherapy. We have also developed a calibration jig specifically for MOSFET dosimeters which promotes reproducible calibration.

The mobileMOSFET dose verification system (TN-RD-70-W) takes MOSFET dosimetry to the next level.

The mobileMOSFET is a portable, easy-to-use, seamlessly integrated system that simplifies dosimetry and minimizes QA time, making it ideal for a busy radiotherapy center.  For example, one Reader Module can be easily shared between multiple treatment rooms (with LAN connections and additional transceivers).

This new wireless system is entirely software driven, allowing for remote control of one or more systems from a PC.  The system consists of Remote Monitoring Dose Verification Software, wall-mounted Bluetooth™ Wireless Transceiver and a small Reader Module that acts as a channel between the MOSFET and software, providing a final dose report for patient records.  Up to five MOSFETs or one Linear 5ive Array can be plugged into one module.  This provides easy mobility within the treatment room.  The PC is online with the Reader Module and the dose is obtained in real time.

The Portable Dosimeter, model TN-RD-90, is an economical, compact, stand-alone system for radiation dose measurement.

Patient dosimetry measurements are available at the touch of a button and display on the integrated LCD, without the need for software or a computer.  Additionally, the rechargeable battery powered dosimeter allows easy transportation from room-to-room, or hospital-to-hospital.

The Portable Dosimeter supports up to two simultaneous dose points with any of the Best Medical Canada single MOSFETs on standard or high bias setting for optimal dose reproducibility.  An automatic mode is available to continuously sample dose data at a fixed time interval during a session.

After every measurement the dosimetry data is automatically stored to memory for later viewing and can be downloaded to a computer via a USB connection and the PortableDose Connect software.  A simple, menu driven interface allows customization of calibration factors, dose units and operational settings directly on the Portable Dosimeter.  To save you time, a library of default calibration factors is stored in the memory, but the user also has the choice of entering their customized calibration factors.

Radiotherapy clinics can utilize the Portable Dosimeter for patient dose QA, or to measure exposures to regions-at-risk.  In diagnostic radiology, the system is ideal for residual exposure dose measurements, and protocol evaluation.

For one-to-two dose points, the Portable dosimeter is a fast, simple solution for patient dosimetry that can be used for a wide range of applications in radiotherapy and radiology.

• Stand-alone reader with LCD
• Portable and compact
• Quick set-up time
• Simple menu operation
• Supports two MOSFET dosimeters
• Supports all single Best Medical Canada MOSFETs
• Optional data export via USB and PortableDose Connect software
• Calibration factor library
• Long rechargeable battery life
• Manual measurement mode, or Automatic Sequential mode
• No software or computer necessary

• In vivo dose – photon or electron
• Skin entrance and exit dose (TBI)
• D_max dose measurements
• IMRT and Tomotherapy
• Brachytherapy

• Pediatric CT dose
• Fluoroscopy dose

The Linear 5ive MOSFET Array for Radiotherapy applications is ideal for LDR/HDR Brachytherapy and IMRT QA.  It is compatible with the mobileMOSFET.  The Array contains five isotropic, energy independent MOSFET dosimeters at 2cm intervals.  The MOSFETs on the array can be read simultaneously, facilitating multiple dose measurements at several spatial points.  The radio-opaque marker, located at the tip of the array, enables visualization under X-ray imaging including CT and Fluoroscopy, allowing for 5 dosimetry points to be accurately located and easily compared to the target doses.

The isotropic Linear 5ive Array, with excellent reproducibility and linearity, is the tool of choice for a variety of radiotherapy applications such as in-vivo dosimetry and Beam Quality Assurance.

The array can be used effectively for direct measurement of intracavitary dose profiles. During gynecological and prostate procedures, five dose points can be read directly from a computer, displaying the dose profile of the organ at risk in real-time.  This is then compared to the planned target dose, allowing for immediate assessments of post-implant base and apex dose, as well as the dose to the organs at risk (eg. urethra, rectum or bladder).

Two arrays crossing at the isocenter of a beam will provide quick 2D dose profiling with 10 simultaneous dose point readings for the X and Y-axes.  Since arrays are isotropic, multiple beams at different gantry angles (as in IMRT) can be accurately and quickly compared.

Best Medical Canada, through CNMC Company, offers three different styles of MOSFET dosimeters. With each of these dosimeters are also options that can be selected.  All our dosimeters have the same unique features:

• One calibration factor for all photon and electron modalities in the radiotherapy energy range
• Isotropic (±3% or better for 360°)
• Active region of 0.2 x 0.2mm
• Permits pinpoint measurement without patient shielding
• Dose-rate and temperature independent
• Unobtrusive in procedures
• Lightweight and flexible
• Multiple dosimeter capability with one reader

Part # TN-RD-70W

The mobileMOSFET Dose Verification System (Part # TN-RD-70W) takes MOSFET dosimetry to the next level.
The mobileMOSFET is a portable, easy-to-use, seamlessly integrated system that simplifies dosimetry and minimizes QA time, making it ideal for a busy radiotherapy center. For example, one Reader Module can be easily shared between multiple treatment rooms (with LAN connections and additional transceivers).
This new wireless system is entirely software driven, allowing for remote control of one or more systems from a PC. The system consists of Remote Monitoring Dose Verification Software, wall-mounted Bluetooth™ Wireless Transceiver, and a small Reader Module that acts as a channel between the MOSFET and software, and provides a final dose report for patient records. Up to five MOSFETs or one Linear 5ive Array can be plugged into one module. This provides easy mobility within the treatment room. The PC is on-line with the Reader Module and dose is obtained in real-time.

Part # TN-RD-90

The Portable Dosimeter (model TN-RD-90) is an economical, compact, stand-alone system for radiation dose measurement.

Patient dosimetry measurements are available at the touch of a button and display on the integrated LCD, without the need for software or a computer.  Additionally, the rechargeable battery powered dosimeter allows easy transportation from room-to-room, or hospital-to-hospital.

The Portable Dosimeter supports up to two simultaneous dose points with any of Arplay Medical’s single MOSFETs on standard or high bias setting for optimal dose reproducibility.  An automatic mode is available to continuously sample dose data at a fixed time interval during a session.

After every measurement the dosimetry data is automatically stored to memory for later viewing and can be downloaded to a computer via a USB connection and the PortableDose Connect software.  A simple, menu driven interface allows customization of calibration factors, dose units and operational settings directly on the Portable Dosimeter.  To save you time, a library of default calibration factors is stored in the memory, but the user also has the choice of entering their customized calibration factors.

Radiotherapy clinics can utilize the Portable Dosimeter for patient dose QA, or to measure exposures to regions-at-risk.  In diagnostic radiology, the system is ideal for residual exposure dose measurements, and protocol evaluation.

For one-to-two dose points, the Portable dosimeter is a fast, simple solution for patient dosimetry that can be used for a wide range of applications in radiotherapy and radiology.

Arplay Medical offers three different styles of MOSFET dosimeters from Best Medical Canada, as shown in the table below.  With each of these dosimeters there are also options that can be selected.  All of our dosimeters have the same unique features:

• One calibration factor for all photon & electron modalities in the radiotherapy energy range.
• Isotropic (± 3% or better for 360º.)
• Active region of 0.2 x 0.2 mm
• Permits pinpoint measurement without patient shielding.
• Dose-rate and temperature independent.
• Unobtrusive in procedures.
• Lightweight and flexible.
• Multiple dosimeter capability with one reader.

The Linear 5ive MOSFET Array™, when used in combination with the mobileMOSFET™, is the first and only commercially available combination that allows for the real-time quality assurance of all brachytherapy procedures, without a significant investment in extra time.

Real-time dose profiling is provided by the in-vivo use of a mobileMOSFET Wireless Dosimetry System. The Linear Array is used for various HDR applications such as prostate and gynecological brachytherapy using model TN-252LA5.

When placed on the surface of the breast, the array can also validate MammoSite™ treatments. Implant and LDR dosimetry is performed using the higher sensitivity model TN-502LA5.

When inserted directly into a urethral catheter, the dose results provide immediate assessment of post-implant base and apex dose coverage, as well as the dose to organs at risk such as the urethra, rectum or bladder. This real-time dose feedback allows assessing the quality of the seed implant program in LDR and HDR brachytherapy. Absolute dose measurements or dose rate measurements are obtained in real-time. This will help validate the quality of treatment, and ultimately the quality of life for the patient.

The MOSFET Calibration Jig (TN-RD-57-30) is designed for quick and easy MOSFET calibration with a simple set-up configuration. The jig reference lines can be easily aligned with the positioning lasers and linear accelerator light fields for 10 x 10 cm, 20 x 20 cm, and 30 x 30 cm fields. The use of the jig promotes easy and consistent positioning at the beam isocenter and, thereby, reproducible calibrations.

The MOSFET placement indentations not only aid positioning, but also prevent accidental damage to the MOSFETs with build-up material during calibration. The staggered positioning reduces the influence of scatter from adjacent MOSFETs and the symmetrical design allows comparison of opposing MOSFETs to each other, and quick verification of beam flatness and symmetry.

The relatively thin 1 cm thickness of the MOSFET Calibration Jig provides a moderate amount of backscatter, but is thin enough to permit customized irradiation set-up with additional backscatter and build-up materials.

Calibration becomes even easier when the MOSFET Calibration Jig is combined with the mobileMOSFET Dose Verification System. The mobileMOSFET is completely software driven and contains a Calibration Module. The Calibration Module collects the calibration dose repetitions in a viewable pool of data. The software automatically calculates the Calibration Factor (CF), the average CF and the percent standard deviation for each MOSFET dosimeter. The CF data file can also be printed, saved, loaded, and edited.

In addition to calibration, the simplicity of the calibration jig lends itself to customized use in phantom-based measurements.  The MOSFET arrangement can be used for dose measurement as a two-dimensional array that provides an inexpensive and quick validation of dose distribution.  Due to the small active volume of the MOSFET (2 x 10^-5mm³), there is limited dose averaging and therefore a better degree of accuracy in high field gradients.  The standardized set-up geometry provides simple entry of positional data to treatment planning software, which can be compared to absolute MOSFET dosimeter measurements.  The MOSFET dosimeters are also isotropic (± 2% for 360°) and have negligible energy dependence, which makes them an ideal dosimeter for IMRT validation.

Typically calibration measurements are done at D_max, but the MOSFET Calibration Jig places the dosimeters on the surface of the jig to allow for customization of build-up.  With no build-up applied, the Calibration Jig can be used for entrance CF estimation during surface dose measurements in radiotherapy or radiology applications.

MOSFETs are known to be highly accurate dosimeters that offer a wide range of measurement options, as one MOSFET can be used for all energies and modalities.  MOSFET dosimeters have only 0.8mm inherent build-up, which allows for flexibility in measuring surface doses as well as doses at D_max.  In order to measure doses at D_max, build-up is required.  Measuring accurate doses at depth is of primary concern for the physics community when performing patient dosimetry.  Precise dose measurement verifies that the target volume area has been treated with the appropriate dose, while sparing surrounding tissue and organs.  Current tissue-equivalent build-up caps require a different size for each energy.  Best Medical Canada offers a custom designed Build-up Cap for use with MOSFET Dosimeters, which allows for depth dose measurements over a wide range of energies.

Brass Build-up Caps – 0.635cm Radius (TN-RD-56-0.63)

In order to maintain the isotropic characteristics of the MOSFET dosimeter (±2% for 360°) and allow for one calibration factor for all energies and modalities, it is recommended that a hemispherical build-up cap be used.  This small brass hemisphere is specially grooved for precise placement of the MOSFET and maintains the characteristics which distinguish these devices from other types of dosimeters.

The new brass build-up cap is very lightweight (only 4g) and small (radius: 0.635cm), which makes it ideal for placement on patients.

This build-up cap may be affixed to the MOSFET for the duration of its life (i.e. 200 doses).  Using just one build-up cap for all Photons and some Electron energies makes the dosimeters easier for therapists to use and saves on patient set-up time, as only one dosimeter is required for all energies.  Additionally, this method saves time spent on switching between different sizes of build-up for each treatment, e.g. IMRT with multiple energies.

Brass is a metal alloy containing mainly copper and zinc compounds.  Due to its high density (8.5g/cm³) and to its high Z number (Z ~ 30), it provides the minimal amount of metal needed to achieve full build-up at D_max for a range of photon energies (4, 6, 10 and 18MV) and some electron energies (15 to 18MeV) at a very practical size.

The use of MOSFET Dosimeters under full build-up enables dose sampling at the charged particle equilibrium region, where the radiation response is maximum.

To directly correct for dose readings at D_max, the system’s software allows for Correction Factor (CR) values to be entered which then convert MOSFET response to dose.

These CRs vary between 0.8 and 1.1 and are Linac and calibration setup dependent.  They must be determined for any new MOSFET/Cap combination.  These CRs may be stored in the system’s software dose measurement template.

For example, two sets of CRs were obtained with a Siemens Mevatron Linac at 6 and 18MV photon energies, with a nominal dose of 200 cGy at D_max in water and 10 x 10 cm² field size (100cm Source Axis Distance).  Please refer to the following table for details:

Note: The Correction Factor “CR" is the value used in the system software, along with the Calibration Factor “CF" to convert MOSFET response to dose. Please refer to Operators’ Manuals for further details.

Brass build-up caps are easily attached to the MOSFET.  Circular adhesive patches are provided with the caps to fasten the MOSFET dosimeter to the build-up cap for the duration of the lifetime of the dosimeter.  The cap/MOSFET is then adhered to the patient’s skin using paper tape.

Cleaning – use rubbing alcohol or alcohol swabs, which are usually found in any hospital/clinic environment.

Note: For low electron energies, It is suggested that no build-up is used.  However, if desired, one can use the 1.5cm radius tissue equivalent build-up cap (model TN-RD-55-1.5).

The XWU-IMRT Phantom (TN-RD-52) is ideal for obtaining quantitative dose measurements for film and MOSFET dosimetry.  This 20cm x 20cm block phantom houses film and a minimum of nine MOSFET dosimeters on two orthagonal planes.  One of the planes, containing five MOSFET detection points, is the dividing plane of the two sub-phantoms where a film is housed.  Five absolute MOSFET dose points on the plane of the film provide dose verification.  Easy to use cassettes come with pre-manufactured slots for the dosimeters and allow for greater versatility (Additional cartridge for ion chamber comparison also available).

Reliable and efficient MOSFETs are well suited for Quality Assurance in IMRT programs because they provide quantitative dose measurements. Due to their small size and excellent isotropic response, MOSFETs can be positioned in the XWU-IMRT Phantom for treatment planning QA of IMRT procedures. This can be done with single dosimeters or with the Linear 5ive Array, both in the phantom and on the patient.

CT images of the phantom are acquired and transferred to the RTP workstation.  An IMRT plan is then applied to the phantom with a predetermined iso-center. Computed point doses of all detector locations are acquired and an iso-dose plot of the dividing plane is made.  The iso-dose plot includes iso-dose lines corelated to the dose level of the five detectors. All MOSFETs are calibrated to a known dose.

The phantom is then exposed per IMRT plan with a film placed between the two sub-phantoms.  As such, five dosimeters are in direct contact with the film and the film correlates to the plane of the iso-dose plot made earlier.  All point doses are accessed through the MOSFET Reader and compared to the data generated from the RTP system.

The film is then developed. A template indicating the five superimposed MOSFET dosimeters is used to mark the location of the film.  The iso-dose plot is then superimposed on the film aligned by the five dosimeters.  The iso-dose line(s) originated from the five dosimeter points are traced on the film.  The dose distribution pattern is then visually compared with the film density pattern.  This assures the orientation of the dose distribution, while the five dosimeter points superimposed on the film are used for direct dose verifications.  In addition, the other dosimeters further verify point doses distributed on the plane perpendicular to the film.