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346 Invited Treatment planning and delivery: state of the art
Sl16
Saturday, 21 September 2002
Symposium CERVIX CANCER 344
Invited
Brachytherapy
E. Van Limberoen University Hospita/Gasthuisberg, Dept. of Radiotherapy, Leuven, Belgium In contrast to external beam therapy radiation, brachytherapy is delivered by sources that are placed at a short distance from the target. This can be in an organ as in intracavitary or endoluminal brachytherapy, or straight into the target volume (interstitial brachytherapy), The main effect is that there is a high dose gradient around the sources so that small target volumes can be treated to high doses while critical organs in the neighbourhood are strongly spared. This leads in many cases to a very high ballistic selectivity (treated volume covers planary volume), at least in cases where the target is anatomically reachable by applicators or catheters. It was the oldest technique of radiotherapy already used in the early 20th century, but has been replaced for most indications of wide field RT by the development of external beam facilities. However the last decades there is a renewed interest in brachytherapy for specific indications. This has been supported by the creation of new artificial isotopes, computerised dosimetry and stepping source technology. The latter allows full radioprotection and source dwell time optimisation to influence dose distribution. Together with the integration of sectional imaging f.i. CT and MRI in pelvic and head and neck Iocalisations, ultrasonography in prostate cancers, full 3D evaluation of target covering and doses to critical organs has become possible. Individual adaptation of dose delivery can now be carried with these advances in technology. Brachytherapy can be delivered nowadays at different dose rates: ranging from classical low dose rate (LDR 30-200 Gy/hr), medium dose rate (2 Gy - 12 Gy/hr) or hight dose rate (> 12 Gy/hr). With permanent seed implants (1125 or Pdl03) dose is delivered at very low dose rates. With pulsed dose rate (PDR), fractionation can be adapted so that the biological effects mimick LDR, allowing for an advantage in therapeutic ratio for most tumours (high cd~) versus late normal tissue effects (low a/b) while the advantages of stepping source technology such as dose optimisation can also be exploited. Correct use of the new technological facilities will help to further optimise dose delivery by brachytherapy and will one of the important challenges for the next decades in this field, 345 Invited T r e a t m e n t of cervix carcinoma: state of the art
R. P(~tter Dept. of Radiotherapy and Radiobiology, Vienna University, Vienna, Austria In locally extended cervix cancer (stage IB2, liB >4 cm, III, IVA)radiotherapy represents the treatment of choice consisting of external beam therapy (EBT) combined with intracavitary brachytherapy (ICBT). According to results from 5 randomized trials published in 1999, simultaneous radiochemotherapy with cis-Platinum based chemotherapy improves results significantly, In limited disease (stage IA, IB1, liB <4 cm) radiotherapy presents an alternative to radical surgery with similar results in terms of local control and survival, but with differences with regard to morbidity, In extended disease radiotherapy starts with external beam therapy up to a dose of 45-50 Gy at the ICRU point with a dose per fractionof 1.8-2.0 Gy. The Planning Target Volume (PTV) includes the Gross Tumour Volume (GTV), the Parametria, the upper part of the vagina and the pelvic lymph nodes. Preferably an open conformal four field box technique is applied based On CT assisted computerised :treatment planning. Cis-Platinum chemotherapy is applied simultaneously with EBT (40mg/m=/week). After tumour shrinkage BT is started at the end of EBT aiming at a total dose of -35-40 Gy in point A. The PTV of ICBT includes the GTV at the time of BT taking into account the initial tumour extent. An applicator with two vaginal and one intrauterine source carrier(s) is used, if technically feasible.
Brachytherapy can be given with different dose rates (LDR, HDR, PDR) according to the different traditions, which lead to comparable results if they are applied based on a large clinical experience and if the respective biological and clinical (dis)advantages are taken into account. Treatment planning is based on orthogonal radiographs and the treated volume is adapted to the PTV as much as possible. Doses are calculated at different points for the organs at risk and the PTV (ICRU points). Dose constraints for the rectum and the bladder have to be taken into account (-75 Gy). The total dose of EBT and BT as reported in point A should be about 80-85 Gy. In limited disease ICBT plays a major role and is supplemented by EBT according to the risk of lymph node involvement. Various techniques of combining ICBT and EBT are in use: additional pelvic EBT with sparing of the central region; EBT with central shielding for a certain dose. Dependent on the stage 5 year pelvic control can be reached in up to 80% in stage liB and in up to 60% in stage IIIB disease. The corresponding 5 year survival rates are 60-70% and 30-40%, respectively. In non bulky stage IB 5 year pelvic control is about 90% and survival about 80%. Acute morbidity is limited and mainly due to the digestive tract (e.g. diarrhea) and the urogenital tract (symptoms from transient inflammation). Acute toxicity is increased with simultaneous chemotherapy, especially hematological. Long term adverse side effects are mainly seen at the rectosigmoid, the bowel, the bladder and the vagina. Significant morbidity (Grade Ill/IV) should be clearly below 10% at 5 years. 346
Invited
Treatment planning and delivery: state of the art C. Kirisits, R. P6tter University of Vienna, Dept. of radiotherapy, Wien, Austria Different techniques for the treatment of cervix cancer by intracavitary therapy are used today. Dose delivery is performed at HDR, PDR or LDR using uterine and vaginal applicators with dedicated loading patterns. Depending on its tradition or infrastructure each center applies different methods of treatment planning. In case of radiography based treatment planning the applicator geometry related to the target and the organs at risk is based on orthogonal, stereoshift or reconstruction jig methods. According to the ICRU concept different points related to the patients anatomy (bladder and rectum reference points, pelvic wall reference points and lymphatic trapezoid) and the applicators are defined on the X-ray images. Some centers include additional points depending on their tradition. Using treatment planning systems the dose is calculated at these dose points for prescribing and reporting the treatment. Prescribing is performed using fixed dose regimens to dose points e.g. point A or to achieve appropriate dimensions of isodose shapes by adjusting dwell times and loading patterns. Dose constraints for the doses to the bladder and rectum ICRU reference points are often the basis of the planning process. However, the concept of reference points implies uncertainties as they are often not related to the actual organ position. The use of modern imaging techniques as CT or MR provides further improvement for a conformal cervical cancer brachytherapy. Constraints can be based on volumes receiving at least a reference dose. Dose limits to 2cm 3 and 5cm ~ of organs at risk derived from dose volume histogram (DVH) calculations and an appropriate shape of the DVH for the target volume are possible concepts for dwell time and loading pattern optimization. This technique requires organ contouring on the images taken after the application and prior to irradiation. A good logistic performance and interdisciplinary approach including physicians, physicists and radiotherapy technologists is essential in order to reduce the time for planning and to increase the quality of the treatment. 347
Invited
The Sheffield approach to the care pathway for outpatients receiving radical radiotherapy to the cervix H. Simoson J. Rigley P. Harrison Weston Park Hospital, radiotherapy, Sheffield, United Kingdom Radiotherapy outpatients undergoing external beam radical radiotherapy to
the cervix are referred to the feminine care service.
Saturday, 21 September 2002
Symposium CERVIX CANCER 344
Invited
Brachytherapy
E. Van Limberoen University Hospita/Gasthuisberg, Dept. of Radiotherapy, Leuven, Belgium In contrast to external beam therapy radiation, brachytherapy is delivered by sources that are placed at a short distance from the target. This can be in an organ as in intracavitary or endoluminal brachytherapy, or straight into the target volume (interstitial brachytherapy), The main effect is that there is a high dose gradient around the sources so that small target volumes can be treated to high doses while critical organs in the neighbourhood are strongly spared. This leads in many cases to a very high ballistic selectivity (treated volume covers planary volume), at least in cases where the target is anatomically reachable by applicators or catheters. It was the oldest technique of radiotherapy already used in the early 20th century, but has been replaced for most indications of wide field RT by the development of external beam facilities. However the last decades there is a renewed interest in brachytherapy for specific indications. This has been supported by the creation of new artificial isotopes, computerised dosimetry and stepping source technology. The latter allows full radioprotection and source dwell time optimisation to influence dose distribution. Together with the integration of sectional imaging f.i. CT and MRI in pelvic and head and neck Iocalisations, ultrasonography in prostate cancers, full 3D evaluation of target covering and doses to critical organs has become possible. Individual adaptation of dose delivery can now be carried with these advances in technology. Brachytherapy can be delivered nowadays at different dose rates: ranging from classical low dose rate (LDR 30-200 Gy/hr), medium dose rate (2 Gy - 12 Gy/hr) or hight dose rate (> 12 Gy/hr). With permanent seed implants (1125 or Pdl03) dose is delivered at very low dose rates. With pulsed dose rate (PDR), fractionation can be adapted so that the biological effects mimick LDR, allowing for an advantage in therapeutic ratio for most tumours (high cd~) versus late normal tissue effects (low a/b) while the advantages of stepping source technology such as dose optimisation can also be exploited. Correct use of the new technological facilities will help to further optimise dose delivery by brachytherapy and will one of the important challenges for the next decades in this field, 345 Invited T r e a t m e n t of cervix carcinoma: state of the art
R. P(~tter Dept. of Radiotherapy and Radiobiology, Vienna University, Vienna, Austria In locally extended cervix cancer (stage IB2, liB >4 cm, III, IVA)radiotherapy represents the treatment of choice consisting of external beam therapy (EBT) combined with intracavitary brachytherapy (ICBT). According to results from 5 randomized trials published in 1999, simultaneous radiochemotherapy with cis-Platinum based chemotherapy improves results significantly, In limited disease (stage IA, IB1, liB <4 cm) radiotherapy presents an alternative to radical surgery with similar results in terms of local control and survival, but with differences with regard to morbidity, In extended disease radiotherapy starts with external beam therapy up to a dose of 45-50 Gy at the ICRU point with a dose per fractionof 1.8-2.0 Gy. The Planning Target Volume (PTV) includes the Gross Tumour Volume (GTV), the Parametria, the upper part of the vagina and the pelvic lymph nodes. Preferably an open conformal four field box technique is applied based On CT assisted computerised :treatment planning. Cis-Platinum chemotherapy is applied simultaneously with EBT (40mg/m=/week). After tumour shrinkage BT is started at the end of EBT aiming at a total dose of -35-40 Gy in point A. The PTV of ICBT includes the GTV at the time of BT taking into account the initial tumour extent. An applicator with two vaginal and one intrauterine source carrier(s) is used, if technically feasible.
Brachytherapy can be given with different dose rates (LDR, HDR, PDR) according to the different traditions, which lead to comparable results if they are applied based on a large clinical experience and if the respective biological and clinical (dis)advantages are taken into account. Treatment planning is based on orthogonal radiographs and the treated volume is adapted to the PTV as much as possible. Doses are calculated at different points for the organs at risk and the PTV (ICRU points). Dose constraints for the rectum and the bladder have to be taken into account (-75 Gy). The total dose of EBT and BT as reported in point A should be about 80-85 Gy. In limited disease ICBT plays a major role and is supplemented by EBT according to the risk of lymph node involvement. Various techniques of combining ICBT and EBT are in use: additional pelvic EBT with sparing of the central region; EBT with central shielding for a certain dose. Dependent on the stage 5 year pelvic control can be reached in up to 80% in stage liB and in up to 60% in stage IIIB disease. The corresponding 5 year survival rates are 60-70% and 30-40%, respectively. In non bulky stage IB 5 year pelvic control is about 90% and survival about 80%. Acute morbidity is limited and mainly due to the digestive tract (e.g. diarrhea) and the urogenital tract (symptoms from transient inflammation). Acute toxicity is increased with simultaneous chemotherapy, especially hematological. Long term adverse side effects are mainly seen at the rectosigmoid, the bowel, the bladder and the vagina. Significant morbidity (Grade Ill/IV) should be clearly below 10% at 5 years. 346
Invited
Treatment planning and delivery: state of the art C. Kirisits, R. P6tter University of Vienna, Dept. of radiotherapy, Wien, Austria Different techniques for the treatment of cervix cancer by intracavitary therapy are used today. Dose delivery is performed at HDR, PDR or LDR using uterine and vaginal applicators with dedicated loading patterns. Depending on its tradition or infrastructure each center applies different methods of treatment planning. In case of radiography based treatment planning the applicator geometry related to the target and the organs at risk is based on orthogonal, stereoshift or reconstruction jig methods. According to the ICRU concept different points related to the patients anatomy (bladder and rectum reference points, pelvic wall reference points and lymphatic trapezoid) and the applicators are defined on the X-ray images. Some centers include additional points depending on their tradition. Using treatment planning systems the dose is calculated at these dose points for prescribing and reporting the treatment. Prescribing is performed using fixed dose regimens to dose points e.g. point A or to achieve appropriate dimensions of isodose shapes by adjusting dwell times and loading patterns. Dose constraints for the doses to the bladder and rectum ICRU reference points are often the basis of the planning process. However, the concept of reference points implies uncertainties as they are often not related to the actual organ position. The use of modern imaging techniques as CT or MR provides further improvement for a conformal cervical cancer brachytherapy. Constraints can be based on volumes receiving at least a reference dose. Dose limits to 2cm 3 and 5cm ~ of organs at risk derived from dose volume histogram (DVH) calculations and an appropriate shape of the DVH for the target volume are possible concepts for dwell time and loading pattern optimization. This technique requires organ contouring on the images taken after the application and prior to irradiation. A good logistic performance and interdisciplinary approach including physicians, physicists and radiotherapy technologists is essential in order to reduce the time for planning and to increase the quality of the treatment. 347
Invited
The Sheffield approach to the care pathway for outpatients receiving radical radiotherapy to the cervix H. Simoson J. Rigley P. Harrison Weston Park Hospital, radiotherapy, Sheffield, United Kingdom Radiotherapy outpatients undergoing external beam radical radiotherapy to
the cervix are referred to the feminine care service.