Limits...
Is the in vivo dosimetry with the OneDosePlusTM system able to detect intra-fraction motion? A retrospective analysis of in vivo data from breast and prostate patients.

Falco MD, D'Andrea M, Bosco AL, Rebuzzi M, Ponti E, Tolu B, Tortorelli G, Barbarino R, Di Murro L, Santoni R - Radiat Oncol (2012)

Bottom Line: The ATs have been found to be very similar (5.0% for TPS1 and 4.5% for TPS2).From statistical data analysis, the system has been found not sensitive enough to reveal displacements smaller than 1 cm (within two standard deviations).Splitting data into medial and lateral field, two patients have been found to move during all these sessions; the others, instead, moved only in the second part of the treatment.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Diagnostic Imaging, Molecular Imaging, Interventional Radiology and Radiotherapy, Tor Vergata University General Hospital, V.le Oxford 81, 00133, Rome, Italy. mdanielafalco@hotmail.com

ABSTRACT

Background: The OneDosePlusTM system, based on MOSFET solid-state radiation detectors and a handheld dosimetry reader, has been used to evaluate intra-fraction movements of patients with breast and prostate cancer.

Methods: An Action Threshold (AT), defined as the maximum acceptable discrepancy between measured dose and dose calculated with the Treatment Planning System (TPS) (for each field) has been determined from phantom data. To investigate the sensitivity of the system to direction of the patient movements, fixed displacements have been simulated in phantom. The AT has been used as an indicator to establish if patients move during a treatment session, after having verified the set-up with 2D and/or 3D images. Phantom tests have been performed matching different linear accelerators and two TPSs (TPS1 and TPS2).

Results: The ATs have been found to be very similar (5.0% for TPS1 and 4.5% for TPS2). From statistical data analysis, the system has been found not sensitive enough to reveal displacements smaller than 1 cm (within two standard deviations). The ATs applied to in vivo treatments showed that among the twenty five patients treated for breast cancer, only four of them moved during each measurement session. Splitting data into medial and lateral field, two patients have been found to move during all these sessions; the others, instead, moved only in the second part of the treatment. Patients with prostate cancer have behaved better than patients with breast cancer. Only two out of twenty five moved in each measurement session.

Conclusions: The method described in the paper, easily implemented in the clinical practice, combines all the advantages of in vivo procedures using the OneDosePlusTM system with the possibility of detecting intra-fraction patient movements.

Show MeSH

Related in: MedlinePlus

OneDosePlusTM system. The system comprises single p-type wireless MOSFET detectors and a handheld reader.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3526469&req=5

Figure 1: OneDosePlusTM system. The system comprises single p-type wireless MOSFET detectors and a handheld reader.

Mentions: The OneDosePlusTM detector system comprises a single p-type wireless MOSFET detector and a handheld reader. The manufacturer provided one reader and individual dosimeters from the same manufacturing lot (Figure1). The MOSFET detectors have physical dimensions of 3.5 x 0.7 cm2 with an active area of 300 x 50 μm2 situated in the center of the exit surface build-up cap. They are provided with an adhesive strip to be attached to the patient’s skin. The build-up cap, instead, is a tin disk of 1.194 ± 0.008 mm thickness (equivalent to 1.4 cm in water) and 5.004 ± 0.254 mm diameter, flash coated with gold to prevent oxidation. A green dot specifies the active area. The dose measured by the detector is the maximum of the Percentage Depth Dose (PDD), and is referred to the corresponding maximum depth, dmax in water. For a 6 MV beam, the measurements correspond to the dose at dmax equal to1.4 cm. For all the other energies, correction factors relate the MOSFET readings to the corresponding doses at dmax.


Is the in vivo dosimetry with the OneDosePlusTM system able to detect intra-fraction motion? A retrospective analysis of in vivo data from breast and prostate patients.

Falco MD, D'Andrea M, Bosco AL, Rebuzzi M, Ponti E, Tolu B, Tortorelli G, Barbarino R, Di Murro L, Santoni R - Radiat Oncol (2012)

OneDosePlusTM system. The system comprises single p-type wireless MOSFET detectors and a handheld reader.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3526469&req=5

Figure 1: OneDosePlusTM system. The system comprises single p-type wireless MOSFET detectors and a handheld reader.
Mentions: The OneDosePlusTM detector system comprises a single p-type wireless MOSFET detector and a handheld reader. The manufacturer provided one reader and individual dosimeters from the same manufacturing lot (Figure1). The MOSFET detectors have physical dimensions of 3.5 x 0.7 cm2 with an active area of 300 x 50 μm2 situated in the center of the exit surface build-up cap. They are provided with an adhesive strip to be attached to the patient’s skin. The build-up cap, instead, is a tin disk of 1.194 ± 0.008 mm thickness (equivalent to 1.4 cm in water) and 5.004 ± 0.254 mm diameter, flash coated with gold to prevent oxidation. A green dot specifies the active area. The dose measured by the detector is the maximum of the Percentage Depth Dose (PDD), and is referred to the corresponding maximum depth, dmax in water. For a 6 MV beam, the measurements correspond to the dose at dmax equal to1.4 cm. For all the other energies, correction factors relate the MOSFET readings to the corresponding doses at dmax.

Bottom Line: The ATs have been found to be very similar (5.0% for TPS1 and 4.5% for TPS2).From statistical data analysis, the system has been found not sensitive enough to reveal displacements smaller than 1 cm (within two standard deviations).Splitting data into medial and lateral field, two patients have been found to move during all these sessions; the others, instead, moved only in the second part of the treatment.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Diagnostic Imaging, Molecular Imaging, Interventional Radiology and Radiotherapy, Tor Vergata University General Hospital, V.le Oxford 81, 00133, Rome, Italy. mdanielafalco@hotmail.com

ABSTRACT

Background: The OneDosePlusTM system, based on MOSFET solid-state radiation detectors and a handheld dosimetry reader, has been used to evaluate intra-fraction movements of patients with breast and prostate cancer.

Methods: An Action Threshold (AT), defined as the maximum acceptable discrepancy between measured dose and dose calculated with the Treatment Planning System (TPS) (for each field) has been determined from phantom data. To investigate the sensitivity of the system to direction of the patient movements, fixed displacements have been simulated in phantom. The AT has been used as an indicator to establish if patients move during a treatment session, after having verified the set-up with 2D and/or 3D images. Phantom tests have been performed matching different linear accelerators and two TPSs (TPS1 and TPS2).

Results: The ATs have been found to be very similar (5.0% for TPS1 and 4.5% for TPS2). From statistical data analysis, the system has been found not sensitive enough to reveal displacements smaller than 1 cm (within two standard deviations). The ATs applied to in vivo treatments showed that among the twenty five patients treated for breast cancer, only four of them moved during each measurement session. Splitting data into medial and lateral field, two patients have been found to move during all these sessions; the others, instead, moved only in the second part of the treatment. Patients with prostate cancer have behaved better than patients with breast cancer. Only two out of twenty five moved in each measurement session.

Conclusions: The method described in the paper, easily implemented in the clinical practice, combines all the advantages of in vivo procedures using the OneDosePlusTM system with the possibility of detecting intra-fraction patient movements.

Show MeSH
Related in: MedlinePlus