When a linear accelerator with one independently moving leaf is used with a wedge in the beam, there is a chance that the independent jaw cannot be used because...
The COLLIMATOR may have to be turned in a direction such that the independent jaw cannot be used
TheThe attends attenuation if Cerrobend is about ___% (less than/ greater) than lead.
Cerrobend attenuates 15% less than lead
The potential hazards of working in the mold room where alloy shields are made consist of-(list 4)
- 1) inhalation of vapors and dust particles
- 2)ingestion of small fragments of the metal
- 3)skin penetration
To reduce the risks of ingestion fragments of the alloy in the block room, the following precautions should be taken-
Practice good hand hygiene before eating, drinking and smoking
Multilevel collimators are different from custom shaped blocks because-
The produce step like edges, leakage can occur between leaves, and they can only be used with limited field sizes
Custom made electron locks are different from custom blocks for photon beams because -
They have NO FOCUSED EDGE and are much thinner; also, the size of of the opening is practically the same as the field on the skin surface.
When a skin lesion is treated using an electron or orthovoltage beam, the shielding -
Should be placed directly on the patient, covering a large area surrounding the lesion
Secondary scatter in the tissue-metal interface can cause____ dose in the adjacent tissues but can be ______by.....
- placing 2-4mm of tissue equivalent material over the teeth
When a lip lesion is treated, it is possible to reduce mucosal reaction by
Placing an internal shield distal to the tumor and covering the shield with a coating of wax
When a missing tissue compensator is used in a photon beam, the compensator should be placed....
At some distance from the skin surface.
The most practical material to use when making a compensator for a photon beam is(name 5)
(NOT LEAD or other higH Z materials!)
- 4)brass(like DOT DECIMAL)
Bomarriage rial is used to
Reduce the depth of maximum dose when PHOTON beam is used
????doesnt it do the same for an electron beam or is it just used for surface irregularities?????
The function of the Radiologic Physics Center(RPC) is to
- Review patient treatment records, Dosimetry calibration of equipment use in treatment of patients enrolled in clinical trials, and communicate instructive findings to the clinical study groups.
- *Note- even though the RPC is for QA for CLINICAL TRIALS, it has a spillover effect towards ALL treatments.
Departmental weekly chart rounds should include verifying( name 6 things )
- 1)presence of diagnoses
- 2) histology
- 4) presence of consent to treatment
- 5)presence of pathology report
- 6) evidence that patient is making progress
The frequency of port films varies, but they
Should always be taken on the first day of treatment
Electronic portal imaging is a method whereby the patient/beam alignment is checked
after only a few MU have been delivered
Various methods of documenting the treatment parameters include( list 3)
- 2) photograph of each treatment field
- 3)port film of treatment field
???Ask Bout difference between port film and "isos"??????
If a 30 degree wedge is left out of the treatment during 1-5 treatments,
the central axis dose is increased and the isodose curve is affected
*the MOST IMPORTANT Thomas g is when a mistake is discovered to REPORT it to the PHYSICIAN so that he can decide if adjustments are needed
When an error in dose delivery is discovered
THE ATTENDING RADIATION ONCOLOGIST SHOULD BE NOTIFIED
Treatment fields should be labeled in the chart with reference o
An anatomical description, and it should ave a unique number
The able of beam divergence is
Larger farther from the central axis
When parallel opposed fields are used and the isocenter is at mid depth in the chest, the length of the spinal cord is
Longer on the anterior field than the posterior
?? Ask about this.confusing???
When parallel opposed fields are used and the isocenter is at mid depth in the chest, the
The anterior port film should appear exactly as the anterior sim film with respect to anatomy
The size of the magnification device is important because a ______ device is more likely to lead to errors in the magnification factor
A circular magnification device, which is 5 cm in diameter, is placed on the patient's anterior surface where the SSD is 100 cm. the sim film is at 135 cm from the target(TFD). The magnification factor is
A 3D coordinate system is used in RT to describe a point in the patient in respect to the origin. +2 cm on the Y-axis would be located
2 cm cephelad to the origin