Gerhard Ries

Pediatric medulloblastoma: Radiation treatment technique and patterns of failure

PURPOSE In this study factors are analyzed that may potentially influence the site of failure in pediatric medulloblastoma. Patient-related, disease-related, and treatment-related variables are analyzed with a special focus on radiotherapy time-dose and technical factors. METHODS AND MATERIALS Eighty-six children and adolescents with a diagnosis of medulloblastoma were treated in Switzerland during the period 1972-1991. Postoperative megavoltage radiotherapy was delivered to all patients. Simulation and portal films of the whole-brain irradiation (WBI) fields were retrospectively reviewed in 77 patients. The distance from the field margin to the cribiform plate and to the floor of the temporal fossa was carefully assessed and correlated with supratentorial failure-free survival. In 19 children the spine was treated with high-energy electron beams, the remainder with megavoltage photons. Simulation and port films of the posterior fossa fields were also reviewed in 72 patients. The field size and the field limits were evaluated and correlated with posterior fossa failure-free survival. RESULTS In 36 patients (47%) the WBI margins were judged to miss the inferior portion of the frontal and temporal lobes. Twelve patients failed in the supratentorial region and 9 of these patients belonged to the group of 36 children in whom the inferior portion of the brain had been underdosed. On multivariate analysis only field correctness was retained as being significantly correlated with supratentorial failure-free survival (p = 0.049). Neither the total dose to the spinal theca nor the treatment technique (electron vs. photon beams) were significantly correlated with outcome. Posterior fossa failure-free survival was not influenced by total dose, overall treatment time, field size, or field margin correctness. Overall survival was not influenced by any of the radiotherapy-related technical factors. CONCLUSION A correlation between WBI field correctness and supratentorial failure-free survival was observed. Treatment protocols should be considered that limit supratentorial irradiation mainly to subsites at highest risk of relapse. Optimized conformal therapy or proton beam therapy may help to reach this goal. Treating the spine with electron beams was not deletereous. A significant correlation between local control and other technical factors was not observed, including those relating to posterior fossa treatment. The use of small conformal tumor bed boost fields may be prefered to the larger posterior fossa fields usually considered as the standard treatment approach.

Prognosis of human chorionic gonadotropin-producing seminoma treated by postoperative radiotherapy

PURPOSE To clarify the controversy about the management and prognosis of human chorionic gonadotropin-producing seminoma, the records of 132 patients with abnormal human chorionic gonadotropin values treated with radiotherapy were analyzed. METHODS AND MATERIALS The records of 1169 patients with pure seminoma treated in 10 institutions were screened for serum or urinary human chorionic gonadotropin. One hundred and thirty two patients with elevated human chorionic gonadotropin were found: 96 Stage I, 20 IIA, 7 IIB, 8 III and 1 IV. Median age was 34 y., mean follow-up was 5.0 years [range 1-12 y]. All received infradiaphragmatic radiotherapy (median dose 30 Gy), 25 (2 Stage I, 11 IIA, 5 IIB and 7 III) supradiaphragmatic radiotherapy (median dose: 28.5 Gy) and 10 had also initial chemotherapy (3 Stage IIB 6 III and 1 IV). Patients were allocated to three groups according to human chorionic gonadotropin values: (a) moderate elevation: up to 10 times (104 pts), (b) high elevation: 10 to 100 times (20 pts), (c) very high elevation: over 100 times the upper limit of normal value (8 pts). RESULTS The proportion of Stage I, II and III was 76%, 19%, 5% in the ME group versus 50%, 35%, 15% in the high elevation group (p < 0.05). In the very high elevation group there were 7 Stage I and 1 Stage IV. Of 132 patients, six died (three dead of disease, two suicides, one acquired immunodeficiency syndrome). The 5 years overall survival probability was 94%. There were seven recurrences (initial stage: 1 Stage I, 2 IIB, 3 III and 1 IV). Of these, there were one in-field recurrence, 3 out of field and 3 in both sites. In 5 of 7, the human chorionic gonadotrophin level was again elevated at recurrence. The 5 years recurrence-free-survival probability was 94% (98% for Stage I, 100% for Stage IIA and 65% for Stage IIB and III [p < 0.001 between I and IIB + III, p < 0.05 between IIA and IIB + III]). Four of the 7 recurrences were salvaged by chimiotherapy +/- radiotherapy. In the high elevation and very high elevation groups, the 5 years recurrence-free-survival was 88%, vs. 96% for the moderate elevation group (p = 0.10). CONCLUSION Based on this series of patients, human chorionic gonadotropin production is not an unfavorable prognostic factor in pure seminoma. Even in the subgroups with high or very high human chorionic gonadotropin levels (who had a higher proportion of advanced stages), the prognosis remained excellent. In Stage I and IIA seminoma with abnormal human chorionic gonadotropin levels, recurrence rate after post-operative radiotherapy alone is extremely low.

Exposure of Treating Physician to Radiation during Prostate Brachytherapy Using Iodine-125 Seeds

Background and Purpose:Only sparse reports have been made about radiation exposure of the treating physician during prostate seed implantation. Therefore, thermoluminescence dosimeter (TLD) measurements on the index fingers and the backs of both hands were conducted.Material and Methods:Stranded iodine-125 seeds with a mean apparent activity of 27.4 MBq per seed were used. During application, the treating physician manipulated the loaded needle with the index fingers, partially under fluoroscopic control. Four physicians with varying experience treated 24 patients. The radiation exposure was determined with TLD-100 chips attached to the index fingertips and the backs of hands. Radiation exposure was correlated with the physician’s experience.Results:The average brachytherapy duration by the most experienced physician was 19.2 min (standard deviation σ = 1.2 min; novices: 34.8 min [σ = 10.2 min]). The mean activity was 1,703 MBq (σ = 123 MBq), applied with 16.3 needles (σ = 2.5 needles; novices: 1,469 MBq [σ = 229 MBq]; 16.8 needles [σ = 2.3 needles]). The exposure of the finger of the “active hand” and the back of the hand amounted to 1.31 mSv (σ = 0.54 mSv) and 0.61 mSv (σ = 0.23 mSv), respectively (novices: 2.07 mSv [σ = 0.86 mSv] and 1.05 mSv [σ = 0.53 mSv]).Conclusion:If no other radiation exposure needs to be considered, an experienced physician can perform about 400 applications per year without exceeding the limit of 500 mSv/year; for novices, the corresponding figure is about 200.Hintergrund und Ziel:Zur Strahlenexposition des applizierenden Arztes bei der Brachytherapie mit Iod-125-Seeds, insbesondere an den Fingern, existieren kaum Informationen. Mit TLD (Thermolumineszenzdosimeter) wurden deshalb Dosismessungen an den die Nadel führenden Zeigefingern und den Handrücken jeweils beider Hände durchgeführt (Abbildung 2) und mit der Erfahrung des Applizierenden korreliert.Material und Methodik:Es wurden Iod-125-Seedketten mit einer mittleren scheinbaren Aktivität von 27,4 MBq pro Seed verwendet (Tabelle 1). Während der Applikation manipulierte der Arzt die beladenen Nadeln mit den Zeigefingern, teilweise unter Durchleuchtung (Abbildung 1). Vier Ärzte mit unterschiedlicher Erfahrung behandelten 24 Patienten. Die Strahlenbelastung wurde mit TLD-100-Chips gemessen, welche auf beide Zeigefinger und die Handrücken aufgeklebt wurden (Abbildung 2).Ergebnisse:Eine Applikation des Arztes mit der größten Erfahrung dauerte durchschnittlich 19,2 min (Standardabweichung σ = 1,2 min), wobei er im Mittel 1 703 MBq (σ = 123 MBq) in 16,3 Nadeln (σ = 2,5 Nadeln) verwendete. Ein unerfahrener Operateur benötigte für eine Applikation von durchschnittlich 1 469 MBq (σ = 229 MBq) mit 16,8 Nadeln (σ = 2,3 Nadeln) im Mittel 34,8 min (σ = 10,2 min) (Abbildungen 3 und 4). Die beim erfahrenen Arzt gemessene mittlere Strahlenexposition des stärker belaste- ten Fingers betrug 1,31 mSv (σ = 0,54 mSv), jene des Handrückens 0,61 mSv (σ = 0,23 mSv). Die korrespondierenden Werte des unerfahrenen Operateurs lagen bei 2,07 mSv (σ = 0,86 mSv) bzw. 1,05 mSv (σ = 0,53 mSv) (Abbildungen 5, 6a und 6b.Schlussfolgerung:Ohne Berücksichtigung anderer Strahlenexpositionen kann ein erfahrener Arzt pro Jahr etwa 400, ein unerfahrener Arzt etwa 200 Applikationen durchführen, ohne den Dosisgrenzwert von 500 mSv/Jahr zu überschreiten.

Exposure of Treating Physician to Radiation during Prostate Brachytherapy Using Iodine-125 Seeds Dose Measurements on Both Hands with Thermoluminescence Dosimeters

Background and Purpose:Only sparse reports have been made about radiation exposure of the treating physician during prostate seed implantation. Therefore, thermoluminescence dosimeter (TLD) measurements on the index fingers and the backs of both hands were conducted.Material and Methods:Stranded iodine-125 seeds with a mean apparent activity of 27.4 MBq per seed were used. During application, the treating physician manipulated the loaded needle with the index fingers, partially under fluoroscopic control. Four physicians with varying experience treated 24 patients. The radiation exposure was determined with TLD-100 chips attached to the index fingertips and the backs of hands. Radiation exposure was correlated with the physician’s experience.Results:The average brachytherapy duration by the most experienced physician was 19.2 min (standard deviation σ = 1.2 min; novices: 34.8 min [σ = 10.2 min]). The mean activity was 1,703 MBq (σ = 123 MBq), applied with 16.3 needles (σ = 2.5 needles; novices: 1,469 MBq [σ = 229 MBq]; 16.8 needles [σ = 2.3 needles]). The exposure of the finger of the “active hand” and the back of the hand amounted to 1.31 mSv (σ = 0.54 mSv) and 0.61 mSv (σ = 0.23 mSv), respectively (novices: 2.07 mSv [σ = 0.86 mSv] and 1.05 mSv [σ = 0.53 mSv]).Conclusion:If no other radiation exposure needs to be considered, an experienced physician can perform about 400 applications per year without exceeding the limit of 500 mSv/year; for novices, the corresponding figure is about 200.Hintergrund und Ziel:Zur Strahlenexposition des applizierenden Arztes bei der Brachytherapie mit Iod-125-Seeds, insbesondere an den Fingern, existieren kaum Informationen. Mit TLD (Thermolumineszenzdosimeter) wurden deshalb Dosismessungen an den die Nadel führenden Zeigefingern und den Handrücken jeweils beider Hände durchgeführt (Abbildung 2) und mit der Erfahrung des Applizierenden korreliert.Material und Methodik:Es wurden Iod-125-Seedketten mit einer mittleren scheinbaren Aktivität von 27,4 MBq pro Seed verwendet (Tabelle 1). Während der Applikation manipulierte der Arzt die beladenen Nadeln mit den Zeigefingern, teilweise unter Durchleuchtung (Abbildung 1). Vier Ärzte mit unterschiedlicher Erfahrung behandelten 24 Patienten. Die Strahlenbelastung wurde mit TLD-100-Chips gemessen, welche auf beide Zeigefinger und die Handrücken aufgeklebt wurden (Abbildung 2).Ergebnisse:Eine Applikation des Arztes mit der größten Erfahrung dauerte durchschnittlich 19,2 min (Standardabweichung σ = 1,2 min), wobei er im Mittel 1 703 MBq (σ = 123 MBq) in 16,3 Nadeln (σ = 2,5 Nadeln) verwendete. Ein unerfahrener Operateur benötigte für eine Applikation von durchschnittlich 1 469 MBq (σ = 229 MBq) mit 16,8 Nadeln (σ = 2,3 Nadeln) im Mittel 34,8 min (σ = 10,2 min) (Abbildungen 3 und 4). Die beim erfahrenen Arzt gemessene mittlere Strahlenexposition des stärker belaste- ten Fingers betrug 1,31 mSv (σ = 0,54 mSv), jene des Handrückens 0,61 mSv (σ = 0,23 mSv). Die korrespondierenden Werte des unerfahrenen Operateurs lagen bei 2,07 mSv (σ = 0,86 mSv) bzw. 1,05 mSv (σ = 0,53 mSv) (Abbildungen 5, 6a und 6b.Schlussfolgerung:Ohne Berücksichtigung anderer Strahlenexpositionen kann ein erfahrener Arzt pro Jahr etwa 400, ein unerfahrener Arzt etwa 200 Applikationen durchführen, ohne den Dosisgrenzwert von 500 mSv/Jahr zu überschreiten.

Exposure of Treating Physician to Radiation during Prostate Brachytherapy Using Iodine-125 Seeds@@@Strahlenexposition des applizierenden Arztes bei der Brachytherapie mit Iod-125-Seeds. Dosismessungen an beiden Händen mit Thermolumineszenzdosimetern: Dose Measurements on Both Hands with Thermoluminescence Dosimeters

Background and Purpose:Only sparse reports have been made about radiation exposure of the treating physician during prostate seed implantation. Therefore, thermoluminescence dosimeter (TLD) measurements on the index fingers and the backs of both hands were conducted.Material and Methods:Stranded iodine-125 seeds with a mean apparent activity of 27.4 MBq per seed were used. During application, the treating physician manipulated the loaded needle with the index fingers, partially under fluoroscopic control. Four physicians with varying experience treated 24 patients. The radiation exposure was determined with TLD-100 chips attached to the index fingertips and the backs of hands. Radiation exposure was correlated with the physician’s experience.Results:The average brachytherapy duration by the most experienced physician was 19.2 min (standard deviation σ = 1.2 min; novices: 34.8 min [σ = 10.2 min]). The mean activity was 1,703 MBq (σ = 123 MBq), applied with 16.3 needles (σ = 2.5 needles; novices: 1,469 MBq [σ = 229 MBq]; 16.8 needles [σ = 2.3 needles]). The exposure of the finger of the “active hand” and the back of the hand amounted to 1.31 mSv (σ = 0.54 mSv) and 0.61 mSv (σ = 0.23 mSv), respectively (novices: 2.07 mSv [σ = 0.86 mSv] and 1.05 mSv [σ = 0.53 mSv]).Conclusion:If no other radiation exposure needs to be considered, an experienced physician can perform about 400 applications per year without exceeding the limit of 500 mSv/year; for novices, the corresponding figure is about 200.Hintergrund und Ziel:Zur Strahlenexposition des applizierenden Arztes bei der Brachytherapie mit Iod-125-Seeds, insbesondere an den Fingern, existieren kaum Informationen. Mit TLD (Thermolumineszenzdosimeter) wurden deshalb Dosismessungen an den die Nadel führenden Zeigefingern und den Handrücken jeweils beider Hände durchgeführt (Abbildung 2) und mit der Erfahrung des Applizierenden korreliert.Material und Methodik:Es wurden Iod-125-Seedketten mit einer mittleren scheinbaren Aktivität von 27,4 MBq pro Seed verwendet (Tabelle 1). Während der Applikation manipulierte der Arzt die beladenen Nadeln mit den Zeigefingern, teilweise unter Durchleuchtung (Abbildung 1). Vier Ärzte mit unterschiedlicher Erfahrung behandelten 24 Patienten. Die Strahlenbelastung wurde mit TLD-100-Chips gemessen, welche auf beide Zeigefinger und die Handrücken aufgeklebt wurden (Abbildung 2).Ergebnisse:Eine Applikation des Arztes mit der größten Erfahrung dauerte durchschnittlich 19,2 min (Standardabweichung σ = 1,2 min), wobei er im Mittel 1 703 MBq (σ = 123 MBq) in 16,3 Nadeln (σ = 2,5 Nadeln) verwendete. Ein unerfahrener Operateur benötigte für eine Applikation von durchschnittlich 1 469 MBq (σ = 229 MBq) mit 16,8 Nadeln (σ = 2,3 Nadeln) im Mittel 34,8 min (σ = 10,2 min) (Abbildungen 3 und 4). Die beim erfahrenen Arzt gemessene mittlere Strahlenexposition des stärker belaste- ten Fingers betrug 1,31 mSv (σ = 0,54 mSv), jene des Handrückens 0,61 mSv (σ = 0,23 mSv). Die korrespondierenden Werte des unerfahrenen Operateurs lagen bei 2,07 mSv (σ = 0,86 mSv) bzw. 1,05 mSv (σ = 0,53 mSv) (Abbildungen 5, 6a und 6b.Schlussfolgerung:Ohne Berücksichtigung anderer Strahlenexpositionen kann ein erfahrener Arzt pro Jahr etwa 400, ein unerfahrener Arzt etwa 200 Applikationen durchführen, ohne den Dosisgrenzwert von 500 mSv/Jahr zu überschreiten.