Background: Comprehensive radiation therapy fields used in the management of early-stage breast cancer. Our aim to determine the variability of the depth of supraclavicular (SCV) & infraclavicular (ICV) nodes, to estimate the actual radiation dose received by these regions in a series of patients treated in the traditional technique, and to compare these doses with those received by using an optimized dosimetric technique. Methods: In 20 patients undergoing treatment-planning computed tomography (CT) scanning in the treatment position, the maximum depth of the SCV and ICV lymph nodes and brachial plexus were measured on CT images. Doses received at the 90% isodose surface for the SCV and ICV volumes were then estimated by using traditional dose calculations and optimized planning. A repeated measures analysis of covariance was used to compare the SCV and ICV depths and to compare the doses achieved with the traditional and optimized methods. Results: We found that SCV nodes> 3 cm and ICV nodes> 4.5 cm will not be covered by 90% isodose surface. However, as the depth to the SCV and ICV nodes increases, the percentage of the SCV volume encompassed within the 90% isodose surface significantly decreases for cases of therapy planned by using traditional planning versus the conformal optimized plan (p 0.05%)

Background: Comprehensive radiation therapy fields used in the management of early-stage breast cancer. Our aim to determine the variability of the depth of supraclavicular (SCV) & infraclavicular (ICV) nodes, to estimate the actual radiation dose received by these regions in a series of patients treated in the traditional technique, and to compare these doses with those received by using an optimized dosimetric technique. Methods: In 20 patients undergoing treatment-planning computed tomography (CT) scanning in the treatment position, the maximum depth of the SCV and ICV lymph nodes and brachial plexus were measured on CT images. Doses received at the 90% isodose surface for the SCV and ICV volumes were then estimated by using traditional dose calculations and optimized planning. A repeated measures analysis of covariance was used to compare the SCV and ICV depths and to compare the doses achieved with the traditional and optimized methods. Results: We found that SCV nodes> 3 cm and ICV nodes> 4.5 cm will not be covered by 90% isodose surface. However, as the depth to the SCV and ICV nodes increases, the percentage of the SCV volume encompassed within the 90% isodose surface significantly decreases for cases of therapy planned by using traditional planning versus the conformal optimized plan (p 0.05%)

The aim of this study was to compare open asymmetric field-in-field (FIF) to physical wedge for compensation of dose inhomogeneity in tangential whole breast irradiation. Patients and Methods: Ten consecutive patients had undergone breast conserving surgery followed by whole breast irradiation were considered. Two 3D treatment plans were generated for each patient using: physical wedge and FIF techniques. For both plans, the doses to 2% (D2) and 98% (D98) of the planning target volume (PTV), as well as PTV95%, PTV97-103%, and PTV>107% of the prescribed dose were used to evaluate the effect on dose homogeneity. The evaluation of organ at risk (OAR) carried out by comparing volumes received over 40% of dose (17Gy) in the ipsilateral lung, 80% of dose (34Gy) in the heart, and mean dose of contralateral lung. Also, the average total monitor units (MU) for both were compared. Results: The FIF technique was better than physical wedged technique in terms of D2, D98, PTV>107%. FIF technique achieved 8.1% dose improvement index compared to physical wedges technique and 34% reduction in the mean monitor units as it reported 470 MU and 310 MU for physical wedges and FIF technique respectively. The differences between the two techniques were insignificant regarding the OAR. FIF can save up to 219 seconds compared to tangential wedged field. Conclusion: Asymmetric FIF technique improves PTV conformity without compromising OAR. It also reduces treatment time and hence can replace physical wedge, especially in busy departments.

The aim of this study was to compare open asymmetric field-in-field (FIF) to physical wedge for compensation of dose inhomogeneity in tangential whole breast irradiation. Patients and Methods: Ten consecutive patients had undergone breast conserving surgery followed by whole breast irradiation were considered. Two 3D treatment plans were generated for each patient using: physical wedge and FIF techniques. For both plans, the doses to 2% (D2) and 98% (D98) of the planning target volume (PTV), as well as PTV95%, PTV97-103%, and PTV>107% of the prescribed dose were used to evaluate the effect on dose homogeneity. The evaluation of organ at risk (OAR) carried out by comparing volumes received over 40% of dose (17Gy) in the ipsilateral lung, 80% of dose (34Gy) in the heart, and mean dose of contralateral lung. Also, the average total monitor units (MU) for both were compared. Results: The FIF technique was better than physical wedged technique in terms of D2, D98, PTV>107%. FIF technique achieved 8.1% dose improvement index compared to physical wedges technique and 34% reduction in the mean monitor units as it reported 470 MU and 310 MU for physical wedges and FIF technique respectively. The differences between the two techniques were insignificant regarding the OAR. FIF can save up to 219 seconds compared to tangential wedged field. Conclusion: Asymmetric FIF technique improves PTV conformity without compromising OAR. It also reduces treatment time and hence can replace physical wedge, especially in busy departments.

The aim of this study was to compare open asymmetric field-in-field (FIF) to physical wedge for compensation of dose inhomogeneity in tangential whole breast irradiation. Patients and Methods: Ten consecutive patients had undergone breast conserving surgery followed by whole breast irradiation were considered. Two 3D treatment plans were generated for each patient using: physical wedge and FIF techniques. For both plans, the doses to 2% (D2) and 98% (D98) of the planning target volume (PTV), as well as PTV95%, PTV97-103%, and PTV>107% of the prescribed dose were used to evaluate the effect on dose homogeneity. The evaluation of organ at risk (OAR) carried out by comparing volumes received over 40% of dose (17Gy) in the ipsilateral lung, 80% of dose (34Gy) in the heart, and mean dose of contralateral lung. Also, the average total monitor units (MU) for both were compared. Results: The FIF technique was better than physical wedged technique in terms of D2, D98, PTV>107%. FIF technique achieved 8.1% dose improvement index compared to physical wedges technique and 34% reduction in the mean monitor units as it reported 470 MU and 310 MU for physical wedges and FIF technique respectively. The differences between the two techniques were insignificant regarding the OAR. FIF can save up to 219 seconds compared to tangential wedged field. Conclusion: Asymmetric FIF technique improves PTV conformity without compromising OAR. It also reduces treatment time and hence can replace physical wedge, especially in busy departments.

Linear accelerators with x-ray collimators that move independently are becoming increasingly common for treatment with asymmetric fields. In this paper we present a simplified approach to the calculation of dose for asymmetric fields. A method is described for calculating the beam profiles, depth doses and output factors for asymmetric fields of radiation produced by linear accelerators (siemens mevatron M2) with independent jaws. Values are calculated from data measured for symmetric fields. Symmetric field data are modified using opened off-axis factors (OAFs) and primary off-centre ratios (POCRs) which are obtained from in air measurements of the largest possible opened field. Beam hardening occurring within the flattening filter is taken into account using of attenuation coefficients for opened field and used to generate the opened POCR at different depths. A full investigation to compare measured and calculated profiles demonstrates favorable agreement

Linear accelerators with x-ray collimators that move independently are becoming increasingly common for treatment with asymmetric fields. In this paper we present a simplified approach to the calculation of dose for asymmetric fields. A method is described for calculating the beam profiles, depth doses and output factors for asymmetric fields of radiation produced by linear accelerators (siemens mevatron M2) with independent jaws. Values are calculated from data measured for symmetric fields. Symmetric field data are modified using opened off-axis factors (OAFs) and primary off-centre ratios (POCRs) which are obtained from in air measurements of the largest possible opened field. Beam hardening occurring within the flattening filter is taken into account using of attenuation coefficients for opened field and used to generate the opened POCR at different depths. A full investigation to compare measured and calculated profiles demonstrates favorable agreement

Linear accelerators with x-ray collimators that move independently are becoming increasingly common for treatment with asymmetric fields. In this paper we present a simplified approach to the calculation of dose for asymmetric fields. A method is described for calculating the beam profiles, depth doses and output factors for asymmetric fields of radiation produced by linear accelerators (siemens mevatron M2) with independent jaws. Values are calculated from data measured for symmetric fields. Symmetric field data are modified using opened off-axis factors (OAFs) and primary off-centre ratios (POCRs) which are obtained from in air measurements of the largest possible opened field. Beam hardening occurring within the flattening filter is taken into account using of attenuation coefficients for opened field and used to generate the opened POCR at different depths. A full investigation to compare measured and calculated profiles demonstrates favorable agreement

The filed shape must be frequently treated in terms of shielding block choices in man clinical applications of electron beam therapy. Because of the difficult of measuring the output factors for individual rectangular electron beam field for each patient, it is necessary to know the output factors for rectangular field size electron beam fields to accurately deliver the prescribed dose to the target. The output factors for rectangular fields have been found that the equivalent area technique generally used in X-ray treatment can be utilized reasonably well to predict the output factors for rectangular electron fiel

The filed shape must be frequently treated in terms of shielding block choices in man clinical applications of electron beam therapy. Because of the difficult of measuring the output factors for individual rectangular electron beam field for each patient, it is necessary to know the output factors for rectangular field size electron beam fields to accurately deliver the prescribed dose to the target. The output factors for rectangular fields have been found that the equivalent area technique generally used in X-ray treatment can be utilized reasonably well to predict the output factors for rectangular electron fiel