- Email: [email protected]
38 Routine measurement of dose to the bladder: Still an utopy ?
SlO
38
37 BRACHYTHERAPY RECONSTRUCTION SCOUT VIEWS FROM THE CT J PCrez* F Ll~so’. V Carmona’.
USING
J Bea’, A Tormo”
ORTHOGONAL
Petachen”
SPAIN
ROUTINE
MEASUREMENT OF DOSE TO THE BLADDER: STILL AN UTOPY ?
B. Schaeken. C. Goor. D. Van den Weyngaert. A Z. Mlddelhelm. Llndendreef 1, B-2020 Antwerpen.
Belgium.
Introduction: CT awsted brachytherapy planmng 1s demonstrating to have great advantages as external RT planning does One of the problems we have found in this approach with the conventional gynecological Fletcher apphcators 15 the high amount of artefacts (ovolds with rectal and vessical protections) m the CT slice We have mtroduced a reconstruchon method based on scou1 wews in order to avoid this problem, allowmg us to perform brachytherapy reconstruchon completely CT assisted. We use a virtual simulation chain by General Electric MedIcal Systems Method and discussion: Two orthogonal scout wews (0 and 90 tube poslhons) are performed The reconstruction method takes Into account the wtual poslhon of the focus and the fact that there 1s only divergence m the transverse plane Algorithms developed for sources as well as for reference pomts localisation (A, B, lymphatic Fletcher trapezoid. pelvic wall, etc ) are presented. This method has the followno practical advantages the porte-cassette is not necessary. the Image qGiity can be tmproied (it is very helpful m pelwc lateral wews that are cntical III conventional radiographs), the total time to get the data IS smaller than for conventional radiographs (reduction of pahent motion effects) and problems that appear in CTslice based reconstruction m the case of strongly curved intrauterine applicators are avoided. Even though the resoluhon IS smaller thar? in convenhonal radiographs It 1s good enough for brachytherapy Regarding the CT planning this method presents the interesting feature that the co-ordmate system IS the same for the reconstruction process that for the CT-slices set. As the applicahon can be reconstructed from scout wews and the doses can be evaluated on CT slices it is easier to correlate the dose values obtamed for the traditional points with those prowded by the CT information.
Doslmetry wth alanme IS based on the relatwe and non destructive measurement of stable lree radicals produced by radlatlon. The llexlblllly 01 the method (Imear dose response. no energy dependence, no dose rate dependence) as well as in detector design makes this method very suited as !n wvo doslmetry system for brachytherapy. Absorbed dose to the detector IS measured as the slgnal tntenslty ol the central lme 01 the electron paramagnehc resonance (EPR) powder spectrum of alanme.
39
40
CT Simulatioo (CTS) in conjuction with high dose rate cndobroncbinl brnchythcrapy (HDR-EB): new perspectives to optimize the treated volume (TrV).
THE F IRST M4NCHESTER CL IN ICAL BR4CHMHERAPY JULY 1989 - JULY 1993
H Mars~&a*, P C Ha~eMeder’. C Strauss**. A VlkJUlf _ France
R Stout, Christie Manchester
Baldeyrou**, B Fredenck’. E Lalt~gau*. E Chlrat*. E Bnot*. M Albano’, M Delapwre*, C PetIt*. Chatel**. A Gerbaulet * *lnstltut Gustave-Roussy . **lnstltut Mutuahste Montsouns - Pans France
Objectives of CTS
To adapt the dose prescnptmn (DP) to the target volume (TV) To correlate TrV, tumour response and treatment morbldlty (therapeutic ratm) The Tr V vanes by a factor of 4 when the depth of the prescnptlon vanes by a factor of 2 Pracbce of CT guided sm~ulatmn ~8th multiplanar rcconstruchon permits dctemmlatmn of the prccwc relatmnshlp between the apphcator, the tumour and vascular structures We have retrospectively stud& 36 patlmts treated wth HDR-EB. I8 with CTS (group A) and I8 whout (group B), to evaluate the efficacy of CTS m dderminmg optlmal adapt&Ion between TrV vs TV Population 36 pts (m&m age 62 yrs. OMS 2) Sdes I5 upper lobe bronchus, I9 mamstem bronchus, 2 tracheas TNM 2 I TI, I I T2. 4 T4. NO MO LarSest dunensmn I cm (m&an) HDR-EB 6 x 5 Gy once the week The cndobronchlal Protocol applicator and a graduated dummy source were placed Just pnor to performmg the CTS The treatment prescnptlon was detemwed by measuring distances from apphcator to tumor and from apphcator to crmcal organs Treated volume was optumzed to obtam the highest therape”t1c ram m&an follow-up 2 years 1 Medlancm 1 Tumor 1 Prescnptm~~ 1 Treated 1 TrV 1 0.5 I Ien@ cmi length I Group ACTS 1 I 1 5 1 13 1 5 [ 7 Group B noCTS 1 I 1 I3 1 5 1 5 1 13 Conclusions Wathever the use of CTS. a h1d1 local control at 2 wars Oo. group B Sh O.). together was observed I” our study (group A wth only a I6 % grade I acute morbldlty (no grade II - III. 110 stenosis or flstulaes) However CTS allowed an optimal therapeutic raoo w!th a 2 fold decrease 111treated volume 1111s could play a long term rob? 111caSeS of ImultIple treatlllam (successwe t”lllO”l)
Resuits
92
The dose at the bladder reference pomt (ICRU 38) can be measured wth no addItIonal mconvemence to the pahent usmg a liquid alan~ne detector (natural 011wth alanme crystals of we less than 200 mm) as follows: the balloon of the Foley catheter IS fllled wth ? 7 cc of llqutd detector Instead of a radio-opaque fluid. By sedlmentahon the alanlne crystals are collected at the posterior surface of the balloon in the wcinlty of the bladder reference pomt. After the treatment the detector IS recuperated from the Foley catheter and read out usmg a small quartz lube. In wtro measurements revealed 1) a periect linear dose response I” the range between 2 Gy and 5 Gy; 2) highly reproducible measurements: 3% (Is) al 1 Gy. 0.3% (1s) at 50 Gy; 3) a mmor quanbty 01 oil IS leakmg through the balloon wall which we expect IS of no harm to the pahent; 4) retriewng the lrradlated alanme crystals from the Foley catheter reduces the EPR stgnal wth a lactor 0.927 f 0.003 (is); 5) subsequent mwng followed by centrlluge of the detector fluId wll result in an EPR slgnal stable wthln + 1% (Is): 6) the detector fluid shows an excellent EPR stablhty m a perhod of months after wradlahon. We only recently obtained permisston of the ethlcal committee to use this technique 1” wo; the results of at least one pahent will be discussed.
TRIAL
OF ENDCBRONCH IAL
P V Barber, P Burt, P Hopwood. Hospital United Kingdom Introduction: A randanised trial in advanced lung cancer was ccnpleted in 1993. The aims were to c-are high dose-rate endcbrcnchial brachytherapy (EBT) with conventional x-ray therapy (XRT) for (I) syrrptcm relief, (2) side-effects, (3) survival and to perform a QuaI i ty of Life Analysis. kterial and Methods: 99 patients with inoperable stage I I I non-srral I ccl I endobronchial tumors (thoracic synptans limited to cough, haemoptysis and breathlessness) were treated. Their man age was 68 years, 79 were ml e and 92 had and ECOG 5core of o-2. 49 received EBT as a single treatment, prescribing 15Gy at lcm. 50 were given XRT, 3&y in 8 fractions over 10 days. Results and Discussion: Synptcm relief was the same in both arms for haemcptysis (86%) and breathlessness (64%). There was a significant difference in favwr of XRT (67 v 42%) for cough. Cross-over retreatment for persistent, recurrent or new thoracic syrrptcms MBS required in 51% of the EBT and 2% of XRT group. Acute morbidity was greater with XRT reaching statistical significance for dysphagia (55 v Late morbidity was the saw. The incidence of 1%). lTassive fatal haemoptysis \IBS only 7%. The median survival was better with XRT (287 v 250 days). The survival difference at 2 years was 10 v 2%. The Q of L Analysis revealed no differences for functional status, anxiety or depressicm but the synptcrr scores confirmd the excess acute morbidity and better synptan control for cough, tiredness and lack of energy in the XRT Conclusion: In this particular patlent popgrwp. ulation XRT is slightly superior to EBT. EBT lazy provide additional benefit hen cabined with XRT.
38
37 BRACHYTHERAPY RECONSTRUCTION SCOUT VIEWS FROM THE CT J PCrez* F Ll~so’. V Carmona’.
USING
J Bea’, A Tormo”
ORTHOGONAL
Petachen”
SPAIN
ROUTINE
MEASUREMENT OF DOSE TO THE BLADDER: STILL AN UTOPY ?
B. Schaeken. C. Goor. D. Van den Weyngaert. A Z. Mlddelhelm. Llndendreef 1, B-2020 Antwerpen.
Belgium.
Introduction: CT awsted brachytherapy planmng 1s demonstrating to have great advantages as external RT planning does One of the problems we have found in this approach with the conventional gynecological Fletcher apphcators 15 the high amount of artefacts (ovolds with rectal and vessical protections) m the CT slice We have mtroduced a reconstruchon method based on scou1 wews in order to avoid this problem, allowmg us to perform brachytherapy reconstruchon completely CT assisted. We use a virtual simulation chain by General Electric MedIcal Systems Method and discussion: Two orthogonal scout wews (0 and 90 tube poslhons) are performed The reconstruction method takes Into account the wtual poslhon of the focus and the fact that there 1s only divergence m the transverse plane Algorithms developed for sources as well as for reference pomts localisation (A, B, lymphatic Fletcher trapezoid. pelvic wall, etc ) are presented. This method has the followno practical advantages the porte-cassette is not necessary. the Image qGiity can be tmproied (it is very helpful m pelwc lateral wews that are cntical III conventional radiographs), the total time to get the data IS smaller than for conventional radiographs (reduction of pahent motion effects) and problems that appear in CTslice based reconstruction m the case of strongly curved intrauterine applicators are avoided. Even though the resoluhon IS smaller thar? in convenhonal radiographs It 1s good enough for brachytherapy Regarding the CT planning this method presents the interesting feature that the co-ordmate system IS the same for the reconstruction process that for the CT-slices set. As the applicahon can be reconstructed from scout wews and the doses can be evaluated on CT slices it is easier to correlate the dose values obtamed for the traditional points with those prowded by the CT information.
Doslmetry wth alanme IS based on the relatwe and non destructive measurement of stable lree radicals produced by radlatlon. The llexlblllly 01 the method (Imear dose response. no energy dependence, no dose rate dependence) as well as in detector design makes this method very suited as !n wvo doslmetry system for brachytherapy. Absorbed dose to the detector IS measured as the slgnal tntenslty ol the central lme 01 the electron paramagnehc resonance (EPR) powder spectrum of alanme.
39
40
CT Simulatioo (CTS) in conjuction with high dose rate cndobroncbinl brnchythcrapy (HDR-EB): new perspectives to optimize the treated volume (TrV).
THE F IRST M4NCHESTER CL IN ICAL BR4CHMHERAPY JULY 1989 - JULY 1993
H Mars~&a*, P C Ha~eMeder’. C Strauss**. A VlkJUlf _ France
R Stout, Christie Manchester
Baldeyrou**, B Fredenck’. E Lalt~gau*. E Chlrat*. E Bnot*. M Albano’, M Delapwre*, C PetIt*. Chatel**. A Gerbaulet * *lnstltut Gustave-Roussy . **lnstltut Mutuahste Montsouns - Pans France
Objectives of CTS
To adapt the dose prescnptmn (DP) to the target volume (TV) To correlate TrV, tumour response and treatment morbldlty (therapeutic ratm) The Tr V vanes by a factor of 4 when the depth of the prescnptlon vanes by a factor of 2 Pracbce of CT guided sm~ulatmn ~8th multiplanar rcconstruchon permits dctemmlatmn of the prccwc relatmnshlp between the apphcator, the tumour and vascular structures We have retrospectively stud& 36 patlmts treated wth HDR-EB. I8 with CTS (group A) and I8 whout (group B), to evaluate the efficacy of CTS m dderminmg optlmal adapt&Ion between TrV vs TV Population 36 pts (m&m age 62 yrs. OMS 2) Sdes I5 upper lobe bronchus, I9 mamstem bronchus, 2 tracheas TNM 2 I TI, I I T2. 4 T4. NO MO LarSest dunensmn I cm (m&an) HDR-EB 6 x 5 Gy once the week The cndobronchlal Protocol applicator and a graduated dummy source were placed Just pnor to performmg the CTS The treatment prescnptlon was detemwed by measuring distances from apphcator to tumor and from apphcator to crmcal organs Treated volume was optumzed to obtam the highest therape”t1c ram m&an follow-up 2 years 1 Medlancm 1 Tumor 1 Prescnptm~~ 1 Treated 1 TrV 1 0.5 I Ien@ cmi length I Group ACTS 1 I 1 5 1 13 1 5 [ 7 Group B noCTS 1 I 1 I3 1 5 1 5 1 13 Conclusions Wathever the use of CTS. a h1d1 local control at 2 wars Oo. group B Sh O.). together was observed I” our study (group A wth only a I6 % grade I acute morbldlty (no grade II - III. 110 stenosis or flstulaes) However CTS allowed an optimal therapeutic raoo w!th a 2 fold decrease 111treated volume 1111s could play a long term rob? 111caSeS of ImultIple treatlllam (successwe t”lllO”l)
Resuits
92
The dose at the bladder reference pomt (ICRU 38) can be measured wth no addItIonal mconvemence to the pahent usmg a liquid alan~ne detector (natural 011wth alanme crystals of we less than 200 mm) as follows: the balloon of the Foley catheter IS fllled wth ? 7 cc of llqutd detector Instead of a radio-opaque fluid. By sedlmentahon the alanlne crystals are collected at the posterior surface of the balloon in the wcinlty of the bladder reference pomt. After the treatment the detector IS recuperated from the Foley catheter and read out usmg a small quartz lube. In wtro measurements revealed 1) a periect linear dose response I” the range between 2 Gy and 5 Gy; 2) highly reproducible measurements: 3% (Is) al 1 Gy. 0.3% (1s) at 50 Gy; 3) a mmor quanbty 01 oil IS leakmg through the balloon wall which we expect IS of no harm to the pahent; 4) retriewng the lrradlated alanme crystals from the Foley catheter reduces the EPR stgnal wth a lactor 0.927 f 0.003 (is); 5) subsequent mwng followed by centrlluge of the detector fluId wll result in an EPR slgnal stable wthln + 1% (Is): 6) the detector fluid shows an excellent EPR stablhty m a perhod of months after wradlahon. We only recently obtained permisston of the ethlcal committee to use this technique 1” wo; the results of at least one pahent will be discussed.
TRIAL
OF ENDCBRONCH IAL
P V Barber, P Burt, P Hopwood. Hospital United Kingdom Introduction: A randanised trial in advanced lung cancer was ccnpleted in 1993. The aims were to c-are high dose-rate endcbrcnchial brachytherapy (EBT) with conventional x-ray therapy (XRT) for (I) syrrptcm relief, (2) side-effects, (3) survival and to perform a QuaI i ty of Life Analysis. kterial and Methods: 99 patients with inoperable stage I I I non-srral I ccl I endobronchial tumors (thoracic synptans limited to cough, haemoptysis and breathlessness) were treated. Their man age was 68 years, 79 were ml e and 92 had and ECOG 5core of o-2. 49 received EBT as a single treatment, prescribing 15Gy at lcm. 50 were given XRT, 3&y in 8 fractions over 10 days. Results and Discussion: Synptcm relief was the same in both arms for haemcptysis (86%) and breathlessness (64%). There was a significant difference in favwr of XRT (67 v 42%) for cough. Cross-over retreatment for persistent, recurrent or new thoracic syrrptcms MBS required in 51% of the EBT and 2% of XRT group. Acute morbidity was greater with XRT reaching statistical significance for dysphagia (55 v Late morbidity was the saw. The incidence of 1%). lTassive fatal haemoptysis \IBS only 7%. The median survival was better with XRT (287 v 250 days). The survival difference at 2 years was 10 v 2%. The Q of L Analysis revealed no differences for functional status, anxiety or depressicm but the synptcrr scores confirmd the excess acute morbidity and better synptan control for cough, tiredness and lack of energy in the XRT Conclusion: In this particular patlent popgrwp. ulation XRT is slightly superior to EBT. EBT lazy provide additional benefit hen cabined with XRT.