Gonadal dosimetry and spermatogenic activity was monitored in patients given radiation therapy (RT) after unilateral orchiectomy for seminoma. The RT given was, with minor variations, 3200 rad in 16 fractions in four weeks to the para‐aortic and ipsilateral pelvic inguinal lymphatics in order to include the orchiectomy scar. The incidental amount of radiation to the remaining testicle averaged 78.4 ± 7.4 rad and ranged from 32–178 rad as determined by thermoluminescent dosimetry. Induction of aspermia was documented in ten out of 14 patients who received over 65 rad to the gonad. At lower doses, aspermia may not have occurred or was of short duration. Recovery of sperm in the semen occurred in 12 patients within 30–80 weeks after start of treatment. The data suggest that the time of recovery may be dose dependent within the range of 19–148 rad. During the period of recovery, patients with oligospermic semen may be fertile and should be so advised.
The Stereotactic Alignment for Linear Accelerator (S. A. Linac) system is developed to conveniently improve the alignment accuracy of a conventional linac equipped with stereotactic cones. From the Winston‐Lutz test, the SAlinac system performs three‐dimensional (3D) reconstruction of the quality assurance (QA) ball coordinates with respect to the radiation isocenter, and combines this information with digital images of the laser target to determine the absolute position of the room lasers. A handheld device provides near‐real‐time repositioning advice to enable the user to align the QA ball and room lasers to within 0.25 mm of the centroid of the radiation isocenter. The results of 37 Winston‐Lutz tests over 68 days showed that the median 3D QA ball alignment error was 0.09 mm, and 97% of the time the 3D error was ≤0.25 mm. All 3D isocentric errors in the study were 0.3 mm or less. The median x and y laser alignment coordinate error was 0.09 mm, and 94% of the time the x and y laser error was ≤0.25 mm. A phantom test showed that the system can make submillimeter end‐to‐end accuracy achievable, making a conventional linac a “Submillimeter Knife”.PACS numbers: 87.53.Ly, 87.55.Qr
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