The efficacy and reliability of lung protection during total body irradiation of patients with disseminated malignancies.

The main problem in total body irradiation (TBI) is obtaining a homogenous dose distribution inside the whole irradiated body and ensuring appropriate dose reduction in the lungs. The process of irradiation should be comfortable for the patients and repeatable despite the size and age diversity among patients. The aim of this paper was 1) to check accuracy of the applied dose algorithm and reliability of the measurement technique used in the lung region during TBI taken alternatively on a Cobalt-60 unit and on 15 MV linear accelerators, and 2) to check if the described methodology made it possible to obtain reproducibly of the lowered level of the dose to the lungs for a diverse group of patients. TBI was performed as a preparatory regiment in children and adults with disseminated malignancies undergoing bone marrow transplantation (a dose of 12.6 Gy in the midline/central beam axis). Two consecutive groups of patients were retrospectively included in the study: 15 irradiated with Cobalt-60 and 15 with 15 MV photons. The doses were evaluated for three sections passing through the middle of the lungs and at their upper and lower sides. Two types of detectors: semiconductor and thermoluminescent ones were used simultaneously. The measured doses were evaluated statistically to reveal agreement between readings of the two types of detectors and agreement between the measured doses and those previously calculated. The results of measurements exhibited a not Gaussian-type distribution (dissymmetry). The Wilcoxon-type test revealed compliance between the doses measured with thermoluminescent (TL) and semiconductor (SEM) detectors for all sections passing through the lungs (p>0.05), excluding the lung exit (middle and lower sides) with the Cobalt therapy. The t-Student test used to compare the measured doses with those previously calculated revealed agreement (p>0.05) between the measured doses and those calculated for all lung sections for the 15 MV photon therapy, while for Cobalt therapy such an agreement was at some points doubtful. The calculation algorithm and measurement techniques have proved to be correct, which was revealed by agreement between the doses measured and those calculated. The shielding of the lungs during both types of fields was effective and reproducible as indicated by agreement between the doses measured with the two types of detectors. Better agreement between the measured and calculated doses was found for 15 MV photons than for the Cobalt unit.

How the implementation of an in-vivo dosimetry protocol improved the dose delivery accuracy in head and neck radiotherapy.

Doses were measured in-vivo at the entrance using semiconductor detectors for patients with head and neck tumors. Regular measurements started on January 1st and continued till June 30th, 2001. Then the evaluation of the discrepancies between the measured and calculated doses was made, and it resulted in the changes in the protocol of in-vivo dosimetry made effective by February 1st, 2002. The collection of the measurements was censored by January 30th 2003. The number of patients in the two groups was 285 (1st) and 407 (2nd), respectively. The results exhibited the not-Gaussian distribution of the measured doses in both groups. The average number of dose checks per patient increased from 4.9 to 6.0 (1st vs. 2nd group). The mean relative difference between the measured and calculated doses was: -1.5% vs. -0.5%, whereas the standard deviation (1 SD) decreased from 6.1% to 5.6%. The Mann-Whitney U test detected a significant difference between the 1st and the 2nd group (p=0.00000), which justified the conclusion that the changes implemented in the protocol improved dose delivery accuracy and reproducibility of irradiation.

The accuracy of in vivo dose measurements during Cobalt-60 total body irradiation.

The purpose of this study was to check the agreement between the doses measured during total body irradiation and those previously calculated. The irradiation was performed with the use of lateral and anterior-posterior fields. The lungs were shielded during the anterior-posterior fields only when followed by an electron boost applied to the thorax wall. A cobalt-60 source was used in eight fractions on four consecutive days. Thermoluminscent, semiconductor detectors and ionisation chambers were used for in vivo measurements at several reference points on the body. The agreement between the calculated and measured doses was tested at the p=0.05 level with the use of a Student's test for a group of thirty patients.

Cobalt 60 versus 15 MeV photons during total body irradiation: doses in the critical organs and complexicity of the procedure.

OBJECTIVES: The aim of this work was to compare the doses in critical organs, treatment duration, patient comfort and personnel workload during total body irradiation carried out alternatively with a Cobalt 60 and with 15 MeV photons at linear accelerator. PATIENTS AND METHODS: Twenty consecutive patients irradiated with a Cobalt unit and twenty irradiated with 15 MeV photons in a linear accelerator were used for comparison of the dose delivered. Each irradiation was repeated eight times during four consecutive days up to a total dose of 12.6 Gy in the whole body (below 10 Gy in the lungs). Lateral fields were used in six fractions, and anterior-posterior fields in two fractions. An electron boost to the thorax wall was added. Doses were calculated and measured in-vivo in ten transverse sections. RESULTS: For the patient taken as an example doses in the middle of the lungs were 10.7 Gy for Co-60 and 11.2 Gy for 15 MeV photons without compensators and 9.6 Gy, 9.6 Gy respectively when compensators were applied. Mean doses in the lungs in the group were 9.5 Gy for Co-60 and 9.7 Gy for X 15 MeV, respectively. Duration of the treatment was shorter with the use of the 15 MeV than that with Co-60 by about 20%. Repositioning of the patient during two fractions with the use of X 15 MeV could be eliminated and therefore the patient's comfort increased.

[Intracavitary brachytherapy method using after-loading for treatment of women with endometrial uterine neoplasm]. / Metoda brachyterapii dojamowej technika after-loading w leczeniu kobiet z rakiem blony sluzowej macicy.

We would like to introduce intracavitary brachytherapy using double rod-shaped applicators. The women who are treated with this method are evaluated in III FIGO stage and the patients in stage I and II who could not undergo the operation. This method allows to distribute equally the dose in whole uterus, insertion of the applicators is not difficult. The brachytherapy treatment is well tolerated.

[Combined dose distribution in the small pelvis of postsurgical radiotherapy patients with cancer of the endometrium]. / Laczne rozklady dawek w miednicy mniejszej w pooperacyjnej radioterapii pacjentek z rakiem blony sluzowej macicy.

X-ray's doses in the pelvis area was published and discussed in this paper. On the CT scan base, doses was calculated by the treatment planning system Target 2 plus. The analysis of dose distribution was performed on 26 patients with the postsurgical cancer of endometrium. The treatment was combined teletherapy and brachytherapy techniques.

[Combined calculation of dosage for brachytherapy and external beam therapy in radiation treatment of cervix cancer]. / Laczne obliczenia dawek z brachy i teleterapii w leczeniu radiacyjnym raka szyjki macicy.

In this paper authors present complex doses of ionizing radiation from brachytherapy and external beam therapy. Doses were determined on Computerized Planning System--Target 2 plus for patients with cancer of cervix.