- Email: [email protected]
Improvement in dosimetry practices over 20 years: a historical account from the RPC
Proceedings of the 31s.tAnnual ASTRO Meeting
237
as follows: lower extremity 22, trunk 18, upper extremity 6, head and neck 4. The median size of the tumors was 5.4 cm. Distribution by tumor grade was: Grade I - 4, Grade II - 14, Grade III - 14, and 18 patients were not graded. The histopathological categorization and grading is currently reviewed by one of the authors (HLE). The majority of patients had excisions prior to their referral to our institution. Thirty-three had one excision, 6 had Z6pxcisions and one patient had 5 previous excisions prior to his referral. All 50 patients were treated with Co and/or electron beam therapy. The median dose was 60 Gy at 2 Gy per fraction (range 45-140 Gy). Thirty-seven patients received doses ranging between 50 and 60 Gy at 2 Gy per fraction. Twenty-eight patients received chemotherapy as part of their initial treatment. Most patients received combination chemotherapy of Adriamycin, vincristine, actinomycin D and cytoxan. With a median follow-up of 85 months (range 7-206 months), 41 patients are alive and NED at last contact. Eight patients died of their disease and one died of chemotherapy complications at 9 months. All 5 patients, who recurred locally died within 3 years. Three other patients died of distant metastases. Seven patients developed severe complications of radiation, 4 of whom required surgical correction. In 2 patients, amputations were required because of severe necrosis following doses of 120 and 140 Gy at 10 Gy per fraction under hypoxic conditions.
1055 IMPROVEMENTIN DOSIMETRY
PRACTICES
I. F. Hanson,
P. Kennedy,
The University
of Texas,
OVER 20 YEARS:
G.B. Krefft, M.D. Anderson
A HISTORICAL
J.F. Aguirre, Cancer
Center,
ACCOUNT
FROM THE RPC.
, T. K. Kirby 1515 Holcombe
Blvd.
- Box 235, Houston,
TX 77030
The Radiological Physics Center (RPC) has monitored dosimetry practices since 1969 at institutions in in cooperative clinical trials. Data derive the USA, Canada, and a few in Europe, which are participating from the RPC's three major activities: dosimetry review visits to participating institutions, a mailing program of thermoluminescence dosimeters (TLD), and review of individual patient treatment records to verify accuracy of the reported doses. Our analyses of the results from dosimetry review site visits show a continuous improvement in the It is believed that the bulk of this improvement is due dose measurement ratio of the RPC to institution. Data from the RPC and CRPS also to more reliable chamber factors, reflecting the influence of the ADCL's. This paper will show indicate that dosimetry peactices improve following a review by a physics center. data prior to 1975 and for subsequent years in five-year increments for photon beam calibrations, electron and chamber intercomparison. beam calibrations,
If TLD results on a therapy unit The RPC mailed TLD program has been fully operational since 1983. show a discrepancy in calibration exceeding 5% on two consecutively mailed TLD sets, the institution becomes a priority for a dosimetry review visit. Our data show that 51% of the time the ion chamber measurements are within 3% of the TLD results, thus verifying discrepancies exceeding 5% at 33% of the The TLD program has identified approximately 12 therapy units per year with major calibration institutions. discrepancies. The RPC reviews individual treatment records for patients entered into clinical trials for seven The review includes a calculation by the RPC of the tumor dose delivered using RPC data cooperative groups. and calculative techniques. Typically, the RPC reviews 2.7 points of calculation per patient. For 20% of the patients, the RPC needed to correspond with the institution to clarify or verify submitted data. For 15% of the patients a dose reported to the study group was found to be in error and was revised as a result of the chart check. This work was supported
by PHS Grant CA 10953 awarded
by the National
Cancer
Institute,
DHHS.
1056 A HIGH SPEED lNTERSTlTlAL/lNTRACAVl’PARY TREATMENT PLANNING SYSTEM C. Pla McGill University, Departmentof Radiation Oncology, Montreal, Canada. With the advent of High Dose Rate Afterloacllng machines the standardtreatmentplanning systems are not best suited for the possibilities these new machines offer. The treatment times are on the order of a few minutes and a large variety of source configurations and treatmenttimes are available. There is therefore a need for an interactive treatment planning system with turnaroundtimes on the order of seconds. Such a system has been developped at McGill University, using standard hardware: a Macintosh II computer with 1 Mb memory and a standard video interface. The program makes extensive use of the well designed user interface built into this computer. Digitization of the source positions is acomplished by a direct on-screen matching between the AP and Lateral films (either by superimposing the film directly on the screen or by capturing the film image with a frame grabber) and the corresponding applicator image drawn in the screen from stored applicator data. The system alloys the user to follow the same steps as the radiotherapist does when choosing the treatment parameters, such as the selection of applicators, source loading, applicator orientation according to the AP and lateral films, and finally dose distribution calculation in any desired plane. Since this process takes less than one minute, The dose distribution in the plane containing point A is done automatically.
237
as follows: lower extremity 22, trunk 18, upper extremity 6, head and neck 4. The median size of the tumors was 5.4 cm. Distribution by tumor grade was: Grade I - 4, Grade II - 14, Grade III - 14, and 18 patients were not graded. The histopathological categorization and grading is currently reviewed by one of the authors (HLE). The majority of patients had excisions prior to their referral to our institution. Thirty-three had one excision, 6 had Z6pxcisions and one patient had 5 previous excisions prior to his referral. All 50 patients were treated with Co and/or electron beam therapy. The median dose was 60 Gy at 2 Gy per fraction (range 45-140 Gy). Thirty-seven patients received doses ranging between 50 and 60 Gy at 2 Gy per fraction. Twenty-eight patients received chemotherapy as part of their initial treatment. Most patients received combination chemotherapy of Adriamycin, vincristine, actinomycin D and cytoxan. With a median follow-up of 85 months (range 7-206 months), 41 patients are alive and NED at last contact. Eight patients died of their disease and one died of chemotherapy complications at 9 months. All 5 patients, who recurred locally died within 3 years. Three other patients died of distant metastases. Seven patients developed severe complications of radiation, 4 of whom required surgical correction. In 2 patients, amputations were required because of severe necrosis following doses of 120 and 140 Gy at 10 Gy per fraction under hypoxic conditions.
1055 IMPROVEMENTIN DOSIMETRY
PRACTICES
I. F. Hanson,
P. Kennedy,
The University
of Texas,
OVER 20 YEARS:
G.B. Krefft, M.D. Anderson
A HISTORICAL
J.F. Aguirre, Cancer
Center,
ACCOUNT
FROM THE RPC.
, T. K. Kirby 1515 Holcombe
Blvd.
- Box 235, Houston,
TX 77030
The Radiological Physics Center (RPC) has monitored dosimetry practices since 1969 at institutions in in cooperative clinical trials. Data derive the USA, Canada, and a few in Europe, which are participating from the RPC's three major activities: dosimetry review visits to participating institutions, a mailing program of thermoluminescence dosimeters (TLD), and review of individual patient treatment records to verify accuracy of the reported doses. Our analyses of the results from dosimetry review site visits show a continuous improvement in the It is believed that the bulk of this improvement is due dose measurement ratio of the RPC to institution. Data from the RPC and CRPS also to more reliable chamber factors, reflecting the influence of the ADCL's. This paper will show indicate that dosimetry peactices improve following a review by a physics center. data prior to 1975 and for subsequent years in five-year increments for photon beam calibrations, electron and chamber intercomparison. beam calibrations,
If TLD results on a therapy unit The RPC mailed TLD program has been fully operational since 1983. show a discrepancy in calibration exceeding 5% on two consecutively mailed TLD sets, the institution becomes a priority for a dosimetry review visit. Our data show that 51% of the time the ion chamber measurements are within 3% of the TLD results, thus verifying discrepancies exceeding 5% at 33% of the The TLD program has identified approximately 12 therapy units per year with major calibration institutions. discrepancies. The RPC reviews individual treatment records for patients entered into clinical trials for seven The review includes a calculation by the RPC of the tumor dose delivered using RPC data cooperative groups. and calculative techniques. Typically, the RPC reviews 2.7 points of calculation per patient. For 20% of the patients, the RPC needed to correspond with the institution to clarify or verify submitted data. For 15% of the patients a dose reported to the study group was found to be in error and was revised as a result of the chart check. This work was supported
by PHS Grant CA 10953 awarded
by the National
Cancer
Institute,
DHHS.
1056 A HIGH SPEED lNTERSTlTlAL/lNTRACAVl’PARY TREATMENT PLANNING SYSTEM C. Pla McGill University, Departmentof Radiation Oncology, Montreal, Canada. With the advent of High Dose Rate Afterloacllng machines the standardtreatmentplanning systems are not best suited for the possibilities these new machines offer. The treatment times are on the order of a few minutes and a large variety of source configurations and treatmenttimes are available. There is therefore a need for an interactive treatment planning system with turnaroundtimes on the order of seconds. Such a system has been developped at McGill University, using standard hardware: a Macintosh II computer with 1 Mb memory and a standard video interface. The program makes extensive use of the well designed user interface built into this computer. Digitization of the source positions is acomplished by a direct on-screen matching between the AP and Lateral films (either by superimposing the film directly on the screen or by capturing the film image with a frame grabber) and the corresponding applicator image drawn in the screen from stored applicator data. The system alloys the user to follow the same steps as the radiotherapist does when choosing the treatment parameters, such as the selection of applicators, source loading, applicator orientation according to the AP and lateral films, and finally dose distribution calculation in any desired plane. Since this process takes less than one minute, The dose distribution in the plane containing point A is done automatically.