Abstract
The ability of portal films in combination with diode detectors in estimating in-vivo midline dose distributions during Total Body Irradiation (TBI) has been investigated. A method to estimate midline dose distributions in a lateral field technique for Total Body Irradiation (TBI) by using diodes and portal films has been suggested. The proposed technique has been verified in a phantom simulating quasi-clinical conditions. In order to better assess the reliability of the method in clinical conditions, we tested an algorithm for estimating midline doses in TBI in a number of situations with cork inhomogeneities both symmetrically and asymmetrically positioned with respect to the phantom midline, by on-axis diodes measurements. A good agreement between estimated and measured off-axis midline doses has been found in correspondence of cork inhomogeneities on a phantom simulating the head-thorax-abdomen region; when using high-Z lungs attenuators, the agreement is still acceptable. Regarding on-axis measurements, this agreement is within 1% (considering the sum of opposed fields for nonsymmetrical inhomogeneities), when the longitudinal dimension of the inhomogeneities is large (18 cm). For the critical case of inhomogeneities with a very small longitudinal dimension (6 cm) the agreement is worse but still acceptable for Quality Assurance aims (4.5% in the worst situation of 'large' distance between the inhomogeneities, better than 2% in the other situations). The reproducibility of the exit dose measurements by portal films has been found within 2% (1 S.D.), corresponding to about 1% at the midline level. Results indicate the possibility of application of portal films in combination with semiconductors in the in-vivo estimation of midline dose distributions in lateral opposed fields TBI techniques.
| Original language | English |
|---|---|
| Pages (from-to) | 41-48 |
| Number of pages | 8 |
| Journal | Physica Medica |
| Volume | 12 |
| Issue number | 1 |
| Publication status | Published - Jan 1996 |
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Keywords
- in-vivo dosimetry
- portal dosimetry
- Total Body Irradiation
- treatment verification
ASJC Scopus subject areas
- Biophysics
- Physics and Astronomy(all)
Cite this
Patient dose estimation in TBI using portal film transit dosimetry in combination with semiconductor detectors. / Fiorino, C.; Uleri, C.; Cattaneo, G. M.; Longobardi, B.; Signorotto, P.; Calandrino, R.
In: Physica Medica, Vol. 12, No. 1, 01.1996, p. 41-48.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Patient dose estimation in TBI using portal film transit dosimetry in combination with semiconductor detectors
AU - Fiorino, C.
AU - Uleri, C.
AU - Cattaneo, G. M.
AU - Longobardi, B.
AU - Signorotto, P.
AU - Calandrino, R.
PY - 1996/1
Y1 - 1996/1
N2 - The ability of portal films in combination with diode detectors in estimating in-vivo midline dose distributions during Total Body Irradiation (TBI) has been investigated. A method to estimate midline dose distributions in a lateral field technique for Total Body Irradiation (TBI) by using diodes and portal films has been suggested. The proposed technique has been verified in a phantom simulating quasi-clinical conditions. In order to better assess the reliability of the method in clinical conditions, we tested an algorithm for estimating midline doses in TBI in a number of situations with cork inhomogeneities both symmetrically and asymmetrically positioned with respect to the phantom midline, by on-axis diodes measurements. A good agreement between estimated and measured off-axis midline doses has been found in correspondence of cork inhomogeneities on a phantom simulating the head-thorax-abdomen region; when using high-Z lungs attenuators, the agreement is still acceptable. Regarding on-axis measurements, this agreement is within 1% (considering the sum of opposed fields for nonsymmetrical inhomogeneities), when the longitudinal dimension of the inhomogeneities is large (18 cm). For the critical case of inhomogeneities with a very small longitudinal dimension (6 cm) the agreement is worse but still acceptable for Quality Assurance aims (4.5% in the worst situation of 'large' distance between the inhomogeneities, better than 2% in the other situations). The reproducibility of the exit dose measurements by portal films has been found within 2% (1 S.D.), corresponding to about 1% at the midline level. Results indicate the possibility of application of portal films in combination with semiconductors in the in-vivo estimation of midline dose distributions in lateral opposed fields TBI techniques.
AB - The ability of portal films in combination with diode detectors in estimating in-vivo midline dose distributions during Total Body Irradiation (TBI) has been investigated. A method to estimate midline dose distributions in a lateral field technique for Total Body Irradiation (TBI) by using diodes and portal films has been suggested. The proposed technique has been verified in a phantom simulating quasi-clinical conditions. In order to better assess the reliability of the method in clinical conditions, we tested an algorithm for estimating midline doses in TBI in a number of situations with cork inhomogeneities both symmetrically and asymmetrically positioned with respect to the phantom midline, by on-axis diodes measurements. A good agreement between estimated and measured off-axis midline doses has been found in correspondence of cork inhomogeneities on a phantom simulating the head-thorax-abdomen region; when using high-Z lungs attenuators, the agreement is still acceptable. Regarding on-axis measurements, this agreement is within 1% (considering the sum of opposed fields for nonsymmetrical inhomogeneities), when the longitudinal dimension of the inhomogeneities is large (18 cm). For the critical case of inhomogeneities with a very small longitudinal dimension (6 cm) the agreement is worse but still acceptable for Quality Assurance aims (4.5% in the worst situation of 'large' distance between the inhomogeneities, better than 2% in the other situations). The reproducibility of the exit dose measurements by portal films has been found within 2% (1 S.D.), corresponding to about 1% at the midline level. Results indicate the possibility of application of portal films in combination with semiconductors in the in-vivo estimation of midline dose distributions in lateral opposed fields TBI techniques.
KW - in-vivo dosimetry
KW - portal dosimetry
KW - Total Body Irradiation
KW - treatment verification
UR - http://www.scopus.com/inward/record.url?scp=0029867781&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0029867781&partnerID=8YFLogxK
M3 - Article
VL - 12
SP - 41
EP - 48
JO - Physica Medica
JF - Physica Medica
SN - 1120-1797
IS - 1
ER -